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IBM i IBM i (the i standing for integrated) is an operating system developed by IBM for IBM Power Systems. It was originally released in 1988 as OS/400, as the sole operating system of the IBM AS/400 line of systems. It was renamed to i5/OS in 2004, before being renamed a second time to IBM i in 2008. It is an evolution of the System/38 CPF operating system, with compatibility layers for System/36 SSP and AIX applications. It inherits a number of distinctive features from the System/38 platform, including the Machine Interface, the implementation of object-based addressing on top of a single-level store, and the tight integration of a relational database into the operating system. History Origin OS/400 was developed alongside the AS/400 hardware platform beginning in December 1985. Development began in the aftermath of the failure of the Fort Knox project, which left IBM without a competitive midrange system. During the Fort Knox project, a skunkworks project was started at Rochester by engineers, who succeeded in developing code which allowed System/36 applications to run on top of the System/38, and when Fort Knox was cancelled, this project evolved into an official project to replace both the System/36 and System/38 with a single new hardware and software platform. The project became known as Silverlake (named for Silver Lake in Rochester, Minnesota). The operating system for Silverlake was codenamed XPF (Extended CPF), and had originally begun as a port of CPF to the Fort Knox hardware. In addition to adding support for System/36 applications, some of the user interface and ease-of-use features from the System/36 were carried over to the new operating system. Silverlake was available for field test in June 1988, and was officially announced in August of that year. By that point, it had been renamed to the Application System/400, and the operating system had been named Operating System/400. The move to PowerPC The port to PowerPC required a rewrite of most of the code below the TIMI. Early versions of OS/400 inherited the Horizontal and Vertical Microcode layers of the System/38, although they were renamed to the Horizontal Licensed Internal Code (HLIC) and Vertical Licensed Internal Code (VLIC) respectively. The port to the new hardware replaced IMPI and the associated microcode, which required the VLIC to be rewritten to target PowerPC instead of IMPI, and for the operating system functionality previously implemented in the HLIC microcode to be re-implemented elsewhere. This led to the HLIC and VLIC being replaced with a single layer named the System Licensed Internal Code (SLIC). The SLIC was implemented in an object-oriented style with over 2 million lines of C++ code, replacing all of the HLIC code, and most of the VLIC code. Owing to the amount of work needed to implement the SLIC, IBM Rochester hired several hundred C++ programmers for the project, who worked on the SLIC in parallel to new revisions of the VLIC for the CISC AS/400 systems. The first release of OS/400 to support PowerPC-based hardware was V3R6. Rebranding The AS/400 product line was rebranded multiple times throughout the 1990s and 2000s. As part of the 2004 rebranding to eServer i5, OS/400 was renamed to i5/OS; the 5 signifying the use of POWER5 processors. The first release of i5/OS, V5R3, was described by IBM as "a different name for the same operating system". In 2006, IBM rebranded the AS/400 line one last time to System i. In April 2008, IBM consolidated the System i with the System p platform to create IBM Power Systems. At the same time, i5/OS was renamed to IBM i, in order to remove the association with POWER5 processors. The two most recent versions of the operating system at that time, which had been released as i5/OS V5R4 and V6R1, were renamed to IBM i 5.4 and 6.1. Along with the rebranding to IBM i, IBM changed the versioning nomenclature for the operating system. Prior releases used a Version, Release, Modification scheme, e.g. V2R1M1. This was replaced with a Version.Release scheme, e.g. 6.1. Beginning with IBM i 7.1, IBM replaced the Modification releases with Technology Refreshes. Technology Refreshes are delivered as optional PTFs for specific releases of the operating system which add new functionality or hardware support to the operating system. Architecture When IBM i was first released as OS/400, it was split into two layers, the hardware-dependent System Licensed Internal Code (SLIC) and the hardware-independent Extended Control Program Facility (XPF). These are divided by a hardware abstraction layer called the Technology Independent Machine Interface (TIMI). Later versions of the operating system gained additional layers, including an AIX compatibility layer named Portable Application Solutions Environment (originally known as the Private Address Space Environment), and the Advanced 36 Machine environment which ran System/36 SSP applications in emulation. IBM often uses different names for the TIMI, SLIC and XPF in documentation and marketing materials, for example, the IBM i 7.4 documentation refers to them as the IBM i Machine Interface, IBM i Licensed Internal Code and IBM i Operating System respectively. TIMI The TIMI isolates users and applications from the underlying hardware. This isolation is more thorough than the hardware abstractions of other operating systems, and includes abstracting the instruction set architecture of the processor, the size of the address space and the specifics of I/O and persistence. This is accomplished through two interrelated mechanisms: Compilers for IBM i do not generate native machine code directly, instead they generate a high level intermediate representation defined by the TIMI. When a program is run, the operating system carries out ahead-of-time translation of the TIMI instructions into native machine code for the processor, and stores the generated machine code for future execution of the program. If the translation process changes, or a different CPU instruction set is adopted, the operating system can transparently regenerate the machine code from the TIMI instructions without needing to recompile from source code. Instead of operating on memory addresses, TIMI instructions operate on objects. All data in IBM i, such as data files, source code, programs and regions of allocated memory, are encapsulated inside objects managed by the operating system (c.f. the "Everything is a file" model in Unix). IBM i objects have a fixed type, which defines the set of applicable operations which may be carried out on them (for example, a Program object can be executed, but cannot be edited). The object model hides whether data is stored in primary, or secondary storage. Instead, the operating system automatically handles the process of retrieving and then storing the changes to permanent storage. The hardware isolation provided by the TIMI allowed IBM to replace the AS/400's 48-bit IMPI architecture with the 64-bit RS64 architecture in 1995. Applications compiled on systems using the IMPI instruction set could run on top of the newer RS64 systems without any code changes, recompilation or emulation, while also allowing those applications to avail of 64-bit addressing. There are two different formats of TIMI instructions, known as the Original Machine Interface (OMI) and New Machine Interface (NMI) formats. OMI instructions are essentially the same as the System/38 Machine interface instructions, whereas NMI instructions are lower-level, resembling the W-code intermediate representation format used by IBM's compilers. IBM partially documents the OMI instructions, whereas the NMI instructions are not officially documented. OMI instructions are used by the original AS/400 compilers, whereas NMI instructions are used by the Integrated Language Environment compilers. During the PowerPC port, native support for the OMI format was removed, and replaced with a translator which converted OMI instructions into NMI instructions. The storing of the TIMI instructions alongside the native machine code instructions is known as observability. In 2008, the release of i5/OS V6R1 (later known as IBM i 6.1) introduced a number of changes to the TIMI layer which caused problems for third-party software which removed observability from the application objects shipped to customers. SLIC The SLIC consists of the code which implements the TIMI on top of the IBM Power architecture. In addition to containing most of the functionality typically associated with an operating system kernel, it is responsible for translating TIMI instructions into machine code, and it also implements some high level functionality which is exposed through the TIMI, such as IBM i's integrated relational database. The SLIC implements IBM i's object-based storage model on top of a single-level store addressing scheme, which does not distinguish between primary and secondary storage, and instead manages all types of storage in a single virtual address space. The SLIC is primarily implemented in C++, and replaced the HLIC and VLIC layers used in versions of OS/400 prior to V3R6. XPF The XPF consists of the code which implements the hardware-independent components of the operating system, which are compiled into TIMI instructions. Components of the XPF include the user interface, the Control Language, data management and query utilities, development tools and system management utilities. The XPF also contains the System/36 Environment and System/38 Environment, which provide backwards compatibility APIs and utilities for applications and data migrated from SSP and CPF systems. The XPF is IBM's internal name for this layer, and as the name suggests, began as an evolution of the System/38 Control Program Facility. The XPF is mostly implemented in PL/MI, although other languages are also used. PASE PASE provides binary compatibility for user mode AIX executables which do not interact directly with the AIX kernel, and supports the 32-bit and 64-bit AIX Application Binary Interfaces. PASE was first included in a limited and undocumented form in the V4R3 release of OS/400 to support a port of Smalltalk. It was first announced to customers at the time of the V4R5 release, by which time it had gained significant additional functionality. PASE consists of the AIX userspace running on top of a system call interface implemented by the SLIC. The system call interfaces allows interoperability between PASE and native IBM i applications, for example, PASE applications can access the integrated database, or call native IBM i applications, and vice versa. During the creation of PASE, a new type of single level storage object named a Teraspace was added to the operating system, which allows each PASE process to have a private 1TiB space which is addressed with 64-bit pointers. This was necessary since all IBM i jobs (i.e. processes) typically share the same address space. PASE applications do not use the hardware-independent TIMI instructions, and are instead compiled directly to Power machine code. PASE is distinct from the Qshell environment, which is an implementation of a Unix shell and associated utilities built on top of IBM i's native POSIX-compatible APIs. Features Database management IBM i features an integrated relational database currently known as IBM Db2 for IBM i. The database evolved from the non-relational System/38 database, gaining support for the relational model and SQL. The database originally had no name, instead it was described simply as "data base support". It was given the name DB2/400 in 1994 to indicate comparable functionality to IBM's other commercial databases. Despite the Db2 branding, Db2 for IBM i is an entirely separate codebase to Db2 on other platforms, and is tightly integrated into the SLIC layer of IBM i as opposed to being an optional product. IBM i provides two mechanisms for accessing the integrated database - the so-called native interface, which is based on the database access model of the System/38, and SQL. The native interface consists of the Data Description Specifications (DDS) language, which is used to define schemas and the OPNQRYF command or QQQQRY query API. Certain Db2 for i features such as object-relational database management require SQL and cannot be accessed through the native interface. IBM i has two separate query optimizers known as the Classic Query Engine (CQE) and SQL Query Engine (SQE). These are implemented inside the SLIC alongside a Query Dispatcher which selects the appropriate optimizer depending on the type of the query. Remote access through the native interface and SQL is provided by the Distributed Data Management Architecture (DDM) and Distributed Relational Database Architecture respectively. A storage engine for MySQL and MariaDB named IBMDB2I allows applications designed for those databases to use Db2 for i as a backing store. Other open source databases have been ported to IBM i, including PostgreSQL, MongoDB and Redis. These databases run on the PASE environment, and are independent of the operating system's integrated database features. Networking IBM i supports TCP/IP networking in addition to the proprietary IBM Systems Network Architecture. IBM i systems were historically accessed and managed through IBM 5250 terminals attached to the system with twinax cabling. With the decline of dedicated terminal hardware, modern IBM i systems are typically accessed through 5250 terminal emulators. IBM provides two terminal emulator products for IBM i: IBM i Access Client Solutions is a Java-based client that runs on Linux, macOS and Windows to provide 5250 emulation. IBM i Access for Web/Mobile provides web-based 5250 emulation. In addition, IBM provides a web-based management console and performance analysis product named IBM Navigator for i. Open-source Some of the open source applications ported to IBM i include: Apache HTTP Server Java Node.js OpenSSL Git gcc nginx PHP Python Ruby Lua R MariaDB MySQL Perl Redis MongoDB PostgreSQL Vim Open source software for IBM i is typically packaged using the RPM package format, and installed with the YUM package manager. YUM and RPM replaced the 5733-OPS product, which was previously used to install open source software on IBM i. Ports of open source software to IBM i typically target PASE instead of the native IBM i APIs in order to simplify porting. Programming Programming languages available from IBM for IBM i include RPG, Control Language, C, C++, Pascal, Java, EGL, Smalltalk, COBOL, BASIC, PL/I and REXX. The Integrated Language Environment (ILE) allows programs from ILE compatible languages (C, C++, COBOL, RPG, and CL), to be bound into the same executable and call procedures written in any of the other ILE languages. When PASE was introduced, it was necessary to compile code for PASE on an AIX system. This requirement was removed in OS/400 V5R2 when it became possible to compile code using the IBM XL compiler suite inside PASE itself. Since then, other compilers have been ported to PASE, including gcc. IBM systems may also come with programming and development software such as the Programming Development Manager. IBM provides an Eclipse-based integrated development environment for IBM i named IBM Rational Developer for i. IBM i uses EBCDIC as the default character encoding, but also provides support for ASCII, UCS-2 and UTF-16. Storage In IBM i, disk drives may be grouped into an auxiliary storage pool (ASP) in order to organize data to limit the impact of storage-device failures and to reduce recovery time. If a disk failure occurs, only the data in the pool containing the failed unit needs to be recovered. ASPs may also be used to improve performance by isolating objects with similar performance characteristics, for example journal receivers, in their own pool. By default, all disk drives are assigned to pool 1. The concept of IBM i pools is similar to the Unix/Linux concept of volume groups; however, with IBM i it is typical for all disk drives to be assigned to a single ASP. Security IBM i was one of the first general-purpose operating systems to attain a C2 security rating from the NSA. Support for C2 level security was first added in the V2R3 release of OS/400. Release timeline See also Comparison of operating systems Library (IBM i) Object (IBM i) References External links IBM i site IBM i Documentation IT Jungle - IBM i news website MC Press Online - IBM Midrange Computer news website 1988 software AS/400 IBM operating systems Object-oriented operating systems Power ISA operating systems

Operating System (OS)

SUSE Linux SUSE Linux ( or ; ) is a computer operating system developed by SUSE. It is built on top of the free and open source Linux kernel and is distributed with system and application software from other open source projects. SUSE Linux is of German origin, its name being an acronym of "Software und System-Entwicklung" (software and systems development), and it was mainly developed in Europe. The first version appeared in early 1994, making SUSE one of the oldest existing commercial distributions. It is known for its YaST configuration tool. Novell bought the SUSE (then "SuSE") brands and trademarks in 2003. Novell, one of the founding members of the Open Invention Network, decided to make the community an important part of their development process by opening widely the distribution development to outside contributors in 2005, creating the openSUSE distribution and the openSUSE Project. Novell employed more than 500 developers working on SUSE in 2004. On 27 April 2011, Novell (and SUSE) were acquired by The Attachmate Group, which made SUSE an independent business unit. Later, in October 2014, the entire Attachmate Group, including SUSE, was acquired by the British firm Micro Focus International. SUSE continues to operate as an independent business unit. On 2 July 2018, it was announced that Micro Focus would sell SUSE to Blitz 18-679 GmbH, a subsidiary of EQT Partners, for $2.535 billion. The acquisition was completed on March 18, 2019. History The developer The developing Gesellschaft für Software und System Entwicklung mbH (Lit. Company for Software and System Development) was founded on 2 September 1992 in Nuremberg, Germany, by Roland Dyroff, Thomas Fehr, Burchard Steinbild, and Hubert Mantel. Three of the founders were still mathematics students at a university; Fehr had already graduated and was working as a software engineer. The original idea was that the company would develop software and function as an advisory UNIX group. According to Mantel, the group decided to distribute Linux, offering support. Their name at founding was "S.u.S.E." (Software und System-Entwicklung "Software and systems development"), although the full name has never been used, however. "S.u.S.E." was shortened to "SuSE" in October 1998 and restylized to "SUSE" in 2003. The official logo and current mascot of the distribution is a veiled chameleon officially named GEEKO (a portmanteau of "gecko" and "geek"). As with the company's name, the GEEKO logo has evolved to reflect company name changes. Origins The company started as a service provider, regularly releasing software packages that included Softlanding Linux System (SLS, now defunct) and Slackware and printing UNIX and Linux manuals, and offering technical assistance. These third-party products SUSE initially used had those characteristics and were managed by SUSE in different fashions: In mid-1992, Peter MacDonald created the comprehensive Linux distribution known as SLS, which offered elements such as X and TCP/IP. This was distributed to people who wanted to get Linux via floppy disks. In 1993, Patrick Volkerding cleaned up the SLS Linux distribution, releasing a newer version as Slackware. In 1994, with help from Patrick Volkerding, Slackware scripts were translated into German, which was marked as the first release of S.u.S.E. Linux 1.0 distribution. It was available first on floppies, and then on CDs. To build its own Linux distribution, S.u.S.E. used SLS in 1992 and jurix in 1996 as starting point. This was created by Florian La Roche, who joined the S.u.S.E. team. He began to develop YaST, the installer and configuration tool that would become the central point of the distribution. In 1996, the first distribution under the name S.u.S.E. Linux was published as S.u.S.E. Linux 4.2, a reference to the answer to "The Ultimate Question of Life, the Universe and Everything" from the Hitchhiker's Guide to the Galaxy. YaST's first version number, 0.42, was a similar reference. Expansion Over time, SuSE Linux incorporated many aspects of Red Hat Linux, such as its RPM Package Manager and its file structure. S.u.S.E. became the largest Linux distributor in Germany. In 1997, SuSE, LLC was established under the direction of president and managing partner James Gray in Oakland, California, which enabled the company to develop Linux markets in the Americas and Asia. While Red Hat was ubiquitous in the United States, SuSE Linux continued to grow in Germany as well as in Nordic countries such as Finland and Sweden. In October 1998, the name was changed officially to, SuSE (without dots). Linus Torvalds, the creator of the Linux kernel, used it fairly often. SuSE entered the UK in 1999. In 2001, the company was forced to reduce its staff significantly in order to survive. Novell On 4 November 2003, Novell announced it would acquire SuSE Linux AG for $210 million. The acquisition was finalized in January 2004. In a move to reach its business audience more effectively, SuSE introduced the SUSE Linux Enterprise Server in 2001, and a few months before Novell's purchase, changed the company name to "SUSE Linux". "SUSE" is now a name, not an acronym. According to J. Philips, Novell's corporate technology strategist for the Asia Pacific region, Novell would not "in the medium term" alter the way in which SUSE was developed. At Novell's annual BrainShare conference in 2004, for the first time, all of their computers were run with SUSE Linux and it was announced that the proprietary SUSE administration program YaST2 would be released under the GPL license. The openSUSE Project On 4 August 2005, Novell announced that the SUSE Professional series would become more open, with the launch of the openSUSE Project community. The software always had been open source, but openSUSE opened the development process, allowing developers and users to test and develop it. Previously, all development work had been accomplished in-house by SUSE. Version 10.0 was the first version that offered public beta testing. SUSE Linux 10.0 included both open source and proprietary applications and retail boxed-set editions. As part of the change, YaST Online Update server access became free for all SUSE Linux users, and also for the first time, the GNOME desktop was upgraded to equal status with the traditional KDE. In November 2005, SUSE founder Hubert Mantel announced his resignation from the company. He stated that Novell's acquisition had changed SUSE beyond his expectations and that he did not believe it was the same company that he had founded 13 years earlier. The resignation apparently stemmed from a dispute over the implementation of Ximian products in the GNOME-based default desktop environment for the Linux distribution. He re-joined only a year later. Microsoft agreement On 3 November 2006 (renewed 25 July 2011), Novell signed an agreement with Microsoft covering improvement of SUSE's ability to interoperate with Microsoft Windows, cross-promotion/marketing of both products and patent cross-licensing. The agreement is considered controversial by some in the Free Software community. The Attachmate Group takeover On 22 November 2010, Novell announced that it had agreed to acquisition by The Attachmate Group for $2.2 billion. The Attachmate Group plans to operate Novell as two units with SUSE becoming a stand-alone business, and it anticipates no change to the relationship between the SUSE business and the openSUSE project as a result of this transaction. The U.S. Department of Justice announced that in order to proceed with the first phase of their acquisition of certain patents and patent applications from Novell Inc., CPTN Holdings LLC and its owners would have to alter their original agreements to address the department's antitrust concerns. The department said that, as originally proposed, the deal would jeopardize the ability of open source software, such as Linux, to continue to innovate and compete in the development and distribution of server, desktop, and mobile operating systems as well as middleware and virtualization products. Stipulations regarding the licensing the patents were: All of the Novell patents will be acquired subject to the GNU General Public License, Version 2, a widely adopted open-source license, and the Open Invention Network (OIN) License, a significant license for the Linux System; CPTN does not have the right to limit which of the patents, if any, are available under the OIN license; and Neither CPTN nor its owners will make any statement or take any action with the purpose of influencing or encouraging either Novell or Attachmate to modify which of the patents are available under the OIN license. The acquisition was completed on 27 April 2011. Subsequently, on 23 July 2011 The Attachmate Group launched a new website for the SUSE business. Micro Focus merger On 20 November 2014, the Attachmate Group merged with Micro Focus to form the Micro Focus Group. SUSE is operated as a separate business unit with a dedicated product portfolio. EQT Partners acquisition On 2 July 2018, it was announced that Micro Focus would sell its SUSE business segment to EQT Partners for $2.535 billion. The acquisition was completed on March 18, 2019. Versions SUSE provides a thirteen-year product life cycle for SUSE Linux Enterprise 11 & 12. SUSE distributions SUSE Linux Enterprise Server openSUSE distributions SUSE family products SUSE Linux is available under two brands, openSUSE and SUSE Linux Enterprise. openSUSE is a free, community distribution driven by the openSUSE Project. It includes some of the latest "bleeding edge" Linux technologies and is designed for home users and enthusiasts. SUSE Linux Enterprise is Suse's tested and certified open-source solution for major enterprises. openSUSE vs SUSE Linux Enterprise openSUSE is a freely available, community project that releases versions on a comparatively frequent basis, and generally uses the latest versions of the various open source projects that it includes. SUSE Linux Enterprise is SUSE's commercial edition, which SUSE releases much less frequently, enabling it to offer support more effectively for enterprise and production deployments. It is certified for a wide variety of enterprise applications and offers a number of special enterprise features including, High Availability and Point of Sale extensions. SUSE historically uses a heavily tested subset of packages from openSUSE Linux as the basis for SUSE Linux Enterprise. Starting with openSUSE 15, SUSE made its "Leap" variant directly upgradable to SUSE Linux Enterprise. SUSE Linux Enterprise Server vs Desktop SUSE offers SUSE Linux Enterprise Server and SUSE Linux Enterprise Desktop. Each focuses on packages that fit its specific purpose. For example, SUSE Linux Enterprise Desktop does not include the Apache Web Server, and SUSE Linux Enterprise Server does not include Xgl/Compiz. In contrast, openSUSE does not have separate distributions for server, desktop, and tablets. Rather, its repositories contain the needed software, and use installation patterns to accomplish the same. openSUSE Linux openSUSE is driven by the openSUSE Project community and sponsored by SUSE, to develop and maintain SUSE Linux components. It is the equivalent of the historic "SuSE Linux Professional". After their acquisition of SUSE Linux, Novell (now SUSE) decided to make the community central to their development process. It has a theoretical development cycle of 8 months and a lifetime (duration of the critical updates) of 18 months from the date of release. It is fully and freely available for immediate download. openSUSE was the sixth most popular Linux distribution for 2013 and the fourth most popular for 2014, according to DistroWatch. SUSE Linux Enterprise SUSE develops multiple products for its "enterprise" business line. These business products target corporate environments, with a higher life cycle (10 years, extendable to 13), a longer development cycle (6 to 18 months), a guarantee of stability at the potential expense of development speed, technical support, and certification by independent hardware and software vendors. SUSE Linux Enterprise products are only available for sale (updates fees). SUSE Linux Enterprise has fewer packages than the openSUSE distribution. Most of the differences are desktop applications that are more suited to consumers than to business. The enterprise products are: SUSE Linux Enterprise Server (SLES) is a server-oriented operating system targeted at corporate environments. SUSE Linux Enterprise Real Time is a modified version of SLES supporting low-latency operations where the time factor is critical. SUSE Linux Enterprise Desktop (SLED) is a desktop-oriented operating system targeted at corporate environments. SUSE Linux Enterprise Thin Client (SLETC) is a modified version of SLED targeted at thin client terminals. When installed using a Linux kernel, Novell Open Enterprise Server (OES) uses SUSE Linux Enterprise Server as a platform. This product is also known as OES-Linux. SUSE Linux Enterprise was included with VMware's vSphere licensing, up until June 25, 2014 for 'free', as noted on SUSE Partners website SUSE Studio SUSE's SUSE Studio product was a web interface (built using Ruby on Rails) to openSUSE's KIWI and the Open Build Service tools. It allowed users to put together a custom Linux distribution graphically and to generate output including a large variety of Virtual Machine and Disk Images. SUSE Studio merged with Open Build Service and the resulting project was renamed to SUSE Studio Express in September 2017. See also Linux on IBM Z List of Linux distributions Comparison of Linux distributions SUSE Studio Novell UnixWare Novell Corsair Novell Exposé Caldera OpenLinux and Caldera Network Desktop List of computing mascots :Category:Computing mascots References Citations General sources External links SUSE openSUSE.org Planet SUSE RPM-based Linux distributions Linux distributions

Operating System (OS)

PC-MOS/386 PC-MOS/386 is a multi-user, multitasking computer operating system produced by The Software Link (TSL), announced at COMDEX in November 1986 for February 1987 release. PC-MOS/386, a successor to PC-MOS, can run many MS-DOS programs on the host machine or a terminal connected to it. Unlike MS-DOS, PC-MOS/386 is optimized for the Intel 80386 processor; however early versions will run on any x86 computer. PC-MOS/386 used to be proprietary, but it was released as open-source software in 2017. History The last commercial version produced was v5.01, compatible with MS-DOS 5. It required a memory management unit (MMU) to support memory protection, so was not compatible with 8086 and 8088 processors. MMU support for 286 class machines was provided using a proprietary hardware shim inserted between the processor and its socket. 386 machines did not require any special hardware. Multi-user operation suffered from the limitations of the day including the inability of the processor to schedule and partition running processes. Typically swapping from a foreground to a background process on the same terminal used the keyboard to generate an interrupt and then swap the processes. The cost of RAM (over US$500/Mb in 1987) and the slow and expensive hard disks of the day limited performance. PC-MOS terminals could be x86 computers running terminal emulation software communicating at 9600 or 19200 baud, connected via serial cables. Speeds above this required specialized hardware boards which increased cost, but the speed was not a serious limitation for interacting with text-based programs. PC-MOS also figured prominently in the lawsuit Arizona Retail Systems, Inc. v. The Software Link, Inc., where Arizona Retail Systems claimed The Software Link violated implied warranties on PC-MOS. The case is notable because The Software Link argued that it had disclaimed the implied warranties via a license agreement on the software's shrinkwrap licensing. The result of the case, which Arizona Retail Systems won, helped to establish US legal precedent regarding the enforceability of shrinkwrap licenses. There was a year 2000 problem-like issue in this operating system, first manifesting on 1 August 2012 rather than 1 January 2000: files created on the system from this date on would no longer work. On 21 July 2017 PCMOS/386 was relicensed under GPL v3 and its source code uploaded to GitHub, with the "year 2012" issue corrected. Commands Commands supported by PC-MOS Version 4 are: ABORT ADDDEV ADDTASK ALIAS AUTOCD BATECHO BREAK CALL RETURN CD CLASS CLS COMMAND COMPFILE COPY DATE DEBUG DIR DIRMAP DISKCOPY DISKID DOT ECHO ED ENVSIZE ERASE EXCEPT EXPORT FILEMODE FLUSH FOR FORMAT GOTO HDSETUP HELP IF IMPORT INSERT KEY KEYMAP MD MORE MOS MOSADM MSORT MSYS NEXT ONLY PATH PAUSE PRINT PROMPT RD REL REM REMDEV REMTASK RENAME SEARCH SET SIGNOFF SIGNON SPOOL STOP SWITCH TEXT ENDTEXT TIME TYPE VERIFY WVER See also DoubleDOS Multiuser DOS - Digital Research's unrelated multi-user operating system VM/386 - unrelated multi-tasking DOS environment Virtual DOS machine Multiuser DOS Federation FreeDOS Timeline of operating systems References 1987 software Discontinued operating systems Disk operating systems DOS variants Formerly proprietary software Free software operating systems Assembly language software X86 operating systems

Operating System (OS)

Phantom OS Phantom OS is an operating system (OS) made by mostly Russian programmers (with help of some Uzbeks). It is based on a concept of persistent virtual memory, and uses managed code. It is one of a few OSes not based on classic concepts of Unix-like systems. Its primary goal is to achieve simplicity and effectiveness in both the operating system and application software at the same time. It is free and open-source software (FOSS) released under a GNU Lesser General Public License (LGPL). Phantom is based on the principle that "Everything is an object", in contrast to the Unix-like approach of "Everything is a file". Basics Managed code – Memory protection on object level, rather than process level; absence of pointer arithmetic in managed code avoids many problems that exist and occur in unmanaged code. Global address space – Very effective and inexpensive inter-process communication (IPC). Single (flat) address space allows transfer of objects from one process (application) to another by transferring links to that object. Security is achieved via absence of pointer arithmetic and the inability of an application to get linked to an object other than by calling a public method. Persistence – Application code does not see OS restarts and could live forever—this makes the concept of a file obsolete and any variable or data structure could be stored forever and at the same time be available directly through a pointer. Differently from hibernation that is done in other OSs, persistence lies in the very core principles of the Phantom OS core. It is done transparently for applications; in most cases it requires no reprogramming of an application. Persistence stays even if the computer crashes. Compatibility Two ways to migrate code are offered: Converter from Java virtual machine (JVM) bytecode; will supposedly allow import of bytecode from Java and other programming languages targeting the JVM. The Portable Operating System Interface (POSIX) subsystem allows porting application code from Unix and Linux, although important features of Phantom OS become unavailable. Status , the system exists in alpha version for x86 IA-32 processors. Porting to ARM architecture is underway (currently being tested, not yet ready for use) and porting to MIPS and x86-64 (AMD64) has begun. Kernel operation has been demonstrated at the biggest Russian IT-conferences RIT 2011, ADD 2010, CC 2010, and 2009. The project is open for contributors to join. See also EROS (microkernel) Singularity (operating system) Notes References External links Free software operating systems Hobbyist operating systems Microkernel-based operating systems Microkernels Object-oriented operating systems Real-time operating systems Russian inventions Window-based operating systems

Operating System (OS)

THEOS THEOS, which translates from Greek as "God", is an operating system which started out as OASIS, a microcomputer operating system for small computers that use the Z80 processor. When the operating system was launched for the IBM Personal Computer/AT in 1982, the decision was taken to change the name from OASIS to THEOS, short for THE Operating System. History OASIS The OASIS operating system was originally developed and distributed in 1977 by Phase One Systems of Oakland, California (President Howard Sidorsky). OASIS was developed for the Z80 processor and was the first multi-user operating system for 8-bit microprocessor based computers (Z-80 from Zilog). "OASIS" was a backronym for "Online Application System Interactive Software". OASIS consisted of a multi-user operating system, a powerful Business Basic/Interpreter, C compiler and a powerful text editor. Timothy Williams developed OASIS and was employed at Phase One. The market asked for 16-bit systems but there was no real 16-bit multi-user OS for 16-bit systems. Every month Phase One announced OASIS-16 but it did not come. One day Timothy Williams claimed that he owned OASIS and started a court case against Phase One and claimed several million U.S. dollars. Sidorsky had no choice and claimed Chapter 11. The court case took two years and finally the ruling was that Timothy Williams was allowed to develop the 16-bit version of OASIS but he was not allowed to use the OASIS name anymore. David Shirley presented an alternative history at the Computer Information Centre, an OASIS distributor for the UK in the early 1980s. He said Timothy Williams developed the OASIS operating system and contracted with Phase One Systems to market and sell the product. Development of the 16-bit product was underway, but the product was prematurely announced by POS. This led to pressure to release OASIS early, when it was still not properly debugged or optimised. (OASIS 8-bit was quite well optimised by that point, with many parts hand-coded in Z80 assembler, but that meant then-new 16-bit systems performed nowhere near as well as their 8-bit counterparts). This situation led to Williams becoming dissatisfied with the Phase One company at the time, and forming his own company to market and support the 16-bit OASIS. The company was initially called Oasis Technologies, until Phase One took action to protect the name. Rather than fight a long and expensive court battle, the company and product was renamed "THEOS". Williams created a new company and product name: "THEOS" meaning "the OS" in the sense of "the one" ("Theos" is Greek for "God"). While Williams and Sidorsky where fighting in the court the manufacturers had no 16-bit multi-user OS. That led to the agreement between Microsoft and Santa Cruz Operation to make a new operating system based on Version 7 Unix from Bell Labs. Microsoft purchased a license for Version 7 UNIX from AT&T in 1978, and announced on August 25, 1980, that it would make it available for the 16-bit microcomputer market. Because Microsoft was not able to license the "UNIX" name itself, called Xenix. Microsoft would distribute the product via Larry Michels and his son Doug Michels (Santa Cruz Operation). Seiko also lost patience with THEOS and Williams, and decided to make their own OASIS 16-bit version and hired Dr. Jeffrey Bahr. When Xenix and THEOS became available Seiko did decide to leave this market. Jeffrey Bahr started CET which went on with the development of the 16-bit OASIS compatible software. CET software was complete compatible with OASIS/THEOS and allowed these users to go into the Unix and Microsoft world. Cet acquired the Phase one company. Also, Phase One Systems licenses a porting tool called CET Basic. CET Basic is compatible with THEOS BASIC, MultiUser BASIC, OASIS BASIC, and UX-BASIC. This means you can keep most of your existing source code, and using W/32 BASIC, recompile your THEOS, OASIS, or UX-BASIC programs to work under additional operating systems such as Microsoft Windows, Linux or SCO UNIX. THEOS THEOS operating systems have been distributed by THEOS Software Corporation in Walnut Creek, California, since 1983. As of 2003, Phase One Systems publishes software development tools for THEOS(R) systems. As well as porting tools, Phase One Systems distributed the Freedom query package and Control database package for THEOS systems, used to bring SQL-like data extraction tools to third-party software packages. THEOS was introduced in Europe by Fujitsu and other hardware manufacturers 30 years ago, and is distributed by a number of distributors in Great Britain, Spain, Portugal, Germany, Italy and more. The 'current' version is THEOS Corona Commercial Release 6, which was released in December 2008, and a number of updates have been released since that time. The current Windows Workstation Client (as of May 2009) is version 3.16 from July 2003. Features Originally written in the late 1970s by Timothy S. Williams as a low-cost alternative to the more expensive mini- and mainframe- computers that were popular in the day, OASIS provided time-sharing multiuser facilities to allow several users to utilise the resources of one computer. Similar in concept to MP/M or UNIX, THEOS uses external device drivers rather than a kernel, allowing it to be more portable to other environments, though support has been primarily directed towards industry-standard hardware (i.e. PC's). THEOS is specifically aimed at small business users, with a wide range of vertical-market applications packages being developed and supported by individuals and companies. The languages distributed with THEOS include THEOS Multi-User Basic and C. A powerful EXEC shell language can be used for task automation or to produce a turnkey system. A number of security features exist, including dynamic passwords (where the password includes part of the date or time, or client IP address, or other dynamic elements), allow/deny security, a comprehensive inbound and outbound firewall, and an option to require a certain level of encryption in the workstation connection. In addition, the object file format is proprietary, and the operating system uses Intel "protected mode" to further increase defence against buffer overrun attacks. Commands The following list of commands are supported by the THEOS/OASIS Command String Interpreter (CSI). ACCOUNT ARCHIVE ASSIGN ATTACH BACKUP BASIC BULKERA CACHE CADVERF CHANGE CLASS COMPARE COPYFILE CREATE CSI DEBUG EDIT ERASE ERRMSG EXEC FILELIST FILT8080 FORCE GETFILE HELP INITDISK INITTAPE KILL LIST LOGOFF LOGON MAILBOX MSG PEEK RECEIVE RENAME REPAIR RESTORE SCRIPT SEND SET SHOW SPOOLER START STOP SYSGEN TERMINAL Reception BYTE in 1985 stated that "the functionality of THEOS is somewhere between MS-DOS and UNIX". The magazine criticized the documentation's quality, and concluded that the price was too high compared to other multiuser operating systems for the PC such as Pick and Coherent. See also Multiuser DOS Federation References External links THEOS Software Corporation Historia de OASIS®/THEOS® Corona OASIS Users' Group Archive February 1981 through November 1985 Proprietary operating systems X86 operating systems 1977 software

Operating System (OS)

IBM OS/6 OS/6 (Office System/6 or System 6) is a standalone word processor made by IBM's Office Products Division (OPD), introduced in January, 1977. OS/6 was superseded by the IBM Displaywriter in 1980. Overview The intended configuration is a console with a keyboard, a small, approximately 9" CRT character display and either a daisy wheel or IBM 46/40 ink jet printer, renamed the IBM 6640. Documents are stored on 8-inch floppy diskettes and magnetic stripe card, which is exchangeable with IBM's previous generation of Mag Card Selectrics. The display is pre-WYSIWYG, so special symbols embedded in the displayed text mark formatting information the user can edit. Navigation is pre-mouse and uses arrow keys. In an age before PCs, when typing was still done primarily only by clerical staff, the OS/6 was intended for what IBM envisioned as centralized word processing centers at large organizations. It includes features like mail merge, very high print quality with many formatting options and printers that can feed envelopes or sheets from two drawers, usually referred to within IBM as letterhead and second sheet. Data from Office System/6 can be migrated to IBM 5110 and 5120 with third-party applications. Internally, the OS/6 uses an IBM proprietary 16-bit single-chip microprocessor called the OPD Mini Processor. This processor is a single-chip FET microprocessor designed by Richard Vrba. It had a 16-bit little-endian instruction set built on an 8-bit internal architecture. Sixteen general-purpose registers, implemented as a 32-byte window in memory that operated as a stack, could be used as instruction operands or for indirect references to operands in memory. History Development on OS/6 was done in the "Rio" project at IBM's Austin, Texas facilities. A proposed video display upgrade for the Selectric Mag Card II had been rejected. Instead, it was announced in 1977 that Mag Card II users would be able to add a communications option to link up with System 6. In a 1977 presentation the System 6 was shown with the models 6/430, 6/440, and 6/450. One year later the models 6/442 and 6/452 were shown additionally. System 6 building blocks are monitor, keyboard, magnetic card unit, inkjet, and daisy wheel printers, and a floppy disk station. In 1978, a stand-alone CPU (without magnetic card and printing capabilities) was added to the product line, the IBM 6/420 Information Processor. In 1979, a communication-enabled laser printer and photocopier combination was introduced, the IBM 6670 Information Distributor. Also in 1979, IBM General Systems Division (GSD) introduced IBM 5520 systems, not related to System 6, with some overlapping functionality and performance. OS/6 was superseded by the IBM Displaywriter in 1980. References External links Computer museum A partially working example of a 6/420 on display Computer museum in Dutch IBM computers 16-bit computers Word processors

Operating System (OS)

Windows 9x Windows 9x is a generic term referring to a series of Microsoft Windows computer operating systems produced from 1995 to 2000, which were based on the Windows 95 kernel and its underlying foundation of MS-DOS, both of which were updated in subsequent versions. The first version in the 9x series was Windows 95, which was succeeded by Windows 98 and then Windows Me, which was the third and last version of Windows on the 9x line, until the series was superseded by Windows XP. Windows 9x is predominantly known for its use in home desktops. In 1998, Windows made up 82% of operating system market share. Internal release versions for versions of Windows 9x are 4.x. The internal versions for Windows 95, 98, and Me are 4.0, 4.1, and 4.9, respectively. Previous MS-DOS-based versions of Windows used version numbers of 3.2 or lower. Windows NT, which was aimed at professional users such as networks and businesses, used a similar but separate version number between 3.1 and 4.0. All versions of Windows from Windows XP onwards are based on the Windows NT codebase. History Windows prior to 95 The first independent version of Microsoft Windows, version 1.0, released on November 20, 1985, achieved little popularity. Its name was initially "Interface Manager", but Rowland Hanson, the head of marketing at Microsoft, convinced the company that the name Windows would be more appealing to consumers. Windows 1.0 was not a complete operating system, but rather an "operating environment" that extended MS-DOS. Consequently, it shared the inherent flaws and problems of MS-DOS. The second installment of Microsoft Windows, version 2.0, was released on December 9, 1987, and used the real-mode memory model, which confined it to a maximum of 1 megabyte of memory. In such a configuration, it could run under another multitasking system like DESQview, which used the 286 Protected Mode. Microsoft Windows scored a significant success with Windows 3.0, released in 1990. In addition to improved capabilities given to native applications, Windows also allowed users to better multitask older MS-DOS-based software compared to Windows/386, thanks to the introduction of virtual memory. Microsoft developed Windows 3.1, which included several minor improvements to Windows 3.0, but primarily consisted of bugfixes and multimedia support. It also excluded support for Real mode, and only ran on an Intel 80286 or better processor. In November 1993 Microsoft also released Windows 3.11, a touch-up to Windows 3.1 which included all of the patches and updates that followed the release of Windows 3.1 in early 1992. Meanwhile, Microsoft continued to develop Windows NT. The main architect of the system was Dave Cutler, one of the chief architects of VMS at Digital Equipment Corporation. Microsoft hired him in August 1988 to create a successor to OS/2, but Cutler created a completely new system instead based on his MICA project at Digital. Microsoft announced at its 1991 Professional Developers Conference its intentions to develop a successor to both Windows NT and Windows 3.1's replacement (Windows 95, code-named Chicago), which would unify the two into one operating system. This successor was codenamed Cairo. In hindsight, Cairo was a much more difficult project than Microsoft had anticipated and, as a result, NT and Chicago would not be unified until Windows XP. Windows 95 After Windows 3.11, Microsoft began to develop a new consumer oriented version of the operating system code-named Chicago. Chicago was designed to have support for 32-bit preemptive multitasking, that of which was available in OS/2 and Windows NT, although a 16-bit kernel would remain for the sake of backward compatibility. The Win32 API first introduced with Windows NT was adopted as the standard 32-bit programming interface, with Win16 compatibility being preserved through a technique known as "thunking". A new GUI was not originally planned as part of the release, although elements of the Cairo user interface were borrowed and added as other aspects of the release (notably Plug and Play) slipped. Microsoft did not change all of the Windows code to 32-bit; parts of it remained 16-bit (albeit not directly using real mode) for reasons of compatibility, performance and development time. Additionally it was necessary to carry over design decisions from earlier versions of Windows for reasons of backwards compatibility, even if these design decisions no longer matched a more modern computing environment. These factors immediately began to impact the operating system's efficiency and stability. Microsoft marketing adopted Windows 95 as the product name for Chicago when it was released on August 24, 1995. Microsoft went on to release five different versions of Windows 95: Windows 95 – original release Windows 95 A – included Windows 95 OSR1 slipstreamed into the installation. Windows 95 B – (OSR2) included several major enhancements, Internet Explorer (IE) 3.0 and full FAT32 file system support. Windows 95 B USB – (OSR2.1) included basic USB support. Windows 95 C – (OSR2.5) included all the above features, plus IE 4.0. This was the last 95 version produced. OSR2, OSR2.1, and OSR2.5 were not released to the general public, rather, they were available only to OEMs that would preload the OS onto computers. Some companies sold new hard drives with OSR2 preinstalled (officially justifying this as needed due to the hard drive's capacity). The first Microsoft Plus! add-on pack was sold for Windows 95. Windows 98 On June 25, 1998, Microsoft released Windows 98. It included new hardware drivers and better support for the FAT32 file system which allows support for disk partitions larger than the 2 GB maximum accepted by Windows 95. The USB support in Windows 98 was more robust than the basic support provided by the OEM editions of Windows 95. It also controversially integrated the Internet Explorer 4 browser into the Windows GUI and Windows Explorer file manager. On May 5, 1999, Microsoft released Windows 98 Second Edition, an interim release whose notable features were the addition of Internet Connection Sharing and improved WDM audio and modem support. Internet Connection Sharing is a form of network address translation, allowing several machines on a LAN (Local Area Network) to share a single Internet connection. Windows 98 Second Edition has certain improvements over the original release. Hardware support through device drivers was increased. Many minor problems present in the original Windows 98 were found and fixed which make it, according to many, the most stable release of Windows 9x family—to the extent that commentators used to say that Windows 98's beta version was more stable than Windows 95's final (gamma) version. Windows Me On September 14, 2000, Microsoft introduced Windows Me (Millennium Edition), which upgraded Windows 98 with enhanced multimedia and Internet features. It also introduced the first version of System Restore, which allowed users to revert their system state to a previous "known-good" point in the case of system failure. The first version of Windows Movie Maker was introduced as well. Windows Me was conceived as a quick one-year project that served as a stopgap release between Windows 98 and Whistler (soon to be renamed to Windows XP). Many of the new features were available from the Windows Update site as updates for older Windows versions. As a result, Windows Me was not acknowledged as a distinct operating system along the lines of 95 or 98, and is often included in the Windows 9x series. Windows Me was criticized by users for its instability and unreliability, due to frequent freezes and crashes. A PC World article dubbed Windows Me the "Mistake Edition" and placed it 4th in their "Worst Tech Products of All Time" feature. The inability of users to easily boot into real mode MS-DOS, as in Windows 95 and 98, led users to quickly learn how to hack their Windows Me installations to provide the needed service. Decline The release of Windows 2000 marked a shift in the user experience between the Windows 9x series and the Windows NT series. Windows NT 4.0 suffered from a lack of support for USB, Plug and Play, and DirectX, preventing its users from playing contemporary games, whereas Windows 2000 featured an updated user interface, and better support for both Plug and Play and USB. The release of Windows XP confirmed the change of direction for Microsoft, bringing the consumer and business operating systems together under Windows NT. One by one, support for the Windows 9x series ended, and Microsoft stopped selling the software to end users, then later to OEMs. By March 2004, it was impossible to purchase any versions of the Windows 9x series. End of service life Microsoft continued to support the use of the Windows 9x series until July 11, 2006, when extended support ended for Windows 98, Windows 98 Second Edition (SE), and Windows Millennium Edition (Me) (extended support for Windows 95 ended on December 31, 2001). Microsoft DirectX, a set of standard gaming APIs, stopped being updated on Windows 95 at Version 8.0a. The last version of DirectX supported for Windows 98 and Me is 9.0c. Support for Microsoft Internet Explorer running on any Windows 9x system has also since ended. Internet Explorer 5.5 with Service Pack 2 is the last version of Internet Explorer compatible with Windows 95 and Internet Explorer 6 with Service Pack 1 is the last version compatible with Windows 98 and Me. Internet Explorer 7, the first major update to Internet Explorer 6 in half a decade, was only available for Windows XP SP2 and Windows Vista. The Windows Update website continued to be available for Windows 98, Windows 98SE, and Windows Me after their end of support date (Windows Update was never available for Windows 95), however, during 2011, Microsoft retired the Windows Update v4 website and removed the updates for Windows 98, Windows 98SE, and Windows Me from its servers. Microsoft announced in July 2019 that the Microsoft Internet Games services on Windows Me (and XP) would end on July 31, 2019. The growing number of important updates caused by the end of service life of these pieces of software have slowly made Windows 9x even less practical for everyday use. Today, even open source projects such as Mozilla Firefox will not run on Windows 9x without rework. RetroZilla is a fork of Gecko 1.8.1 aimed at bringing "improved compatibility on the modern web" for versions of Windows as old as Windows 95 and NT 4.0. The latest version, 2.2, was released in February 2019 and added support for TLS 1.2. Design Kernel Windows 9x is a series of hybrid 16/32-bit operating systems. Like most operating systems, Windows 9x consists of kernel space and user space memory. Although Windows 9x features some memory protection, it does not protect the first megabyte of memory from userland applications for compatibility reasons. This area of memory contains code critical to the functioning of the operating system, and by writing into this area of memory an application can crash or freeze the operating system. This was a source of instability as faulty applications could accidentally write into this region, potentially corrupting important operating system memory, which usually resulted in some form of system error and halt. User mode The user-mode parts of Windows 9x consist of three subsystems: the Win16 subsystem, the Win32 subsystem and MS-DOS. Windows 9x/Me set aside two blocks of 64 KB memory regions for GDI and heap resources. By running multiple applications, applications with numerous GDI elements or by running applications over a long span of time, it could exhaust these memory areas. If free system resources dropped below 10%, Windows would become unstable and likely crash. Kernel mode The kernel mode parts consist of the Virtual Machine Manager (VMM), the Installable File System Manager (IFSHLP), the Configuration Manager, and in Windows 98 and later, the WDM Driver Manager (NTKERN). As a 32-bit operating system, virtual memory space is 4 GiB, divided into a lower 2 GiB for applications and an upper 2 GiB for kernel per process. Registry Like Windows NT, Windows 9x stores user-specific and configuration-specific settings in a large information database called the Windows registry. Hardware-specific settings are also stored in the registry, and many device drivers use the registry to load configuration data. Previous versions of Windows used files such as AUTOEXEC.BAT, CONFIG.SYS, WIN.INI, SYSTEM.INI and other files with an .INI extension to maintain configuration settings. As Windows became more complex and incorporated more features, .INI files became too unwieldy for the limitations of the then-current FAT filesystem. Backwards-compatibility with .INI files was maintained until Windows XP succeeded the 9x and NT lines. Although Microsoft discourages using .INI files in favor of Registry entries, a large number of applications (particularly 16-bit Windows-based applications) still use .INI files. Windows 9x supports .INI files solely for compatibility with those applications and related tools (such as setup programs). The AUTOEXEC.BAT and CONFIG.SYS files also still exist for compatibility with real-mode system components and to allow users to change certain default system settings such as the PATH environment variable. The registry consists of two files: User.dat and System.dat. In Windows Me, Classes.dat was added. Virtual Machine Manager The Virtual Machine Manager (VMM) is the 32-bit protected mode kernel at the core of Windows 9x. Its primary responsibility is to create, run, monitor and terminate virtual machines. The VMM provides services that manage memory, processes, interrupts and protection faults. The VMM works with virtual devices (loadable kernel modules, which consist mostly of 32-bit ring 0 or kernel mode code, but may include other types of code, such as a 16-bit real mode initialisation segment) to allow those virtual devices to intercept interrupts and faults to control the access that an application has to hardware devices and installed software. Both the VMM and virtual device drivers run in a single, 32-bit, flat model address space at privilege level 0 (also called ring 0). The VMM provides multi-threaded, preemptive multitasking. It runs multiple applications simultaneously by sharing CPU (central processing unit) time between the threads in which the applications and virtual machines run. The VMM is also responsible for creating MS-DOS environments for system processes and Windows applications that still need to run in MS-DOS mode. It is the replacement for WIN386.EXE in Windows 3.x, and the file vmm32.vxd is a compressed archive containing most of the core VxD, including VMM.vxd itself and ifsmgr.vxd (which facilitates file system access without the need to call the real mode file system code of the DOS kernel). Software support Unicode Partial support for Unicode can be installed on Windows 9x through the Microsoft Layer for Unicode. File systems Windows 9x does not natively support NTFS or HPFS, but there are third-party solutions which allow Windows 9x to have read-only access to NTFS volumes. Early versions of Windows 95 did not support FAT32. Like Windows for Workgroups 3.11, Windows 9x provides support for 32-bit file access based on IFSHLP.SYS, and unlike Windows 3.x, Windows 9x has support for the VFAT file system, allowing file names with a maximum of 255 characters instead of having 8.3 filenames. Event logging and tracing Also, there is no support for event logging and tracing or error reporting which the Windows NT family of operating systems has, although software like Norton CrashGuard can be used to achieve similar capabilities on Windows 9x. Security Windows 9x is designed as a single-user system. Thus, the security model is much less effective than the one in Windows NT. One reason for this is the FAT file systems (including FAT12/FAT16/FAT32), which are the only ones that Windows 9x supports officially, though Windows NT also supports FAT12 and FAT16 (but not FAT32) and Windows 9x can be extended to read and write NTFS volumes using third-party Installable File System drivers. FAT systems have very limited security; every user that has access to a FAT drive also has access to all files on that drive. The FAT file systems provide no access control lists and file-system level encryption like NTFS. Some operating systems that were available at the same time as Windows 9x are either multi-user or have multiple user accounts with different access privileges, which allows important system files (such as the kernel image) to be immutable under most user accounts. In contrast, while Windows 95 and later operating systems offer the option of having profiles for multiple users, they have no concept of access privileges, making them roughly equivalent to a single-user, single-account operating system; this means that all processes can modify all files on the system that aren't open, in addition to being able to modify the boot sector and perform other low-level hard drive modifications. This enables viruses and other clandestinely installed software to integrate themselves with the operating system in a way that is difficult for ordinary users to detect or undo. The profile support in the Windows 9x family is meant for convenience only; unless some registry keys are modified, the system can be accessed by pressing "Cancel" at login, even if all profiles have a password. Windows 95's default login dialog box also allows new user profiles to be created without having to log in first. Users and software can render the operating system unable to function by deleting or overwriting important system files from the hard disk. Users and software are also free to change configuration files in such a way that the operating system is unable to boot or properly function. Installation software often replaced and deleted system files without properly checking if the file was still in use or of a newer version. This created a phenomenon often referred to as DLL hell. Windows Me introduced System File Protection and System Restore to handle common problems caused by this issue. Network sharing Windows 9x offers share-level access control security for file and printer sharing as well as user-level access control if a Windows NT-based operating system is available on the network. In contrast, Windows NT-based operating systems offer only user-level access control but integrated with the operating system's own user account security mechanism. Hardware support Drivers Device drivers in Windows 9x can be virtual device drivers or (starting with Windows 98) WDM drivers. VxDs usually have the filename extension .vxd or .386, whereas WDM compatible drivers usually use the extension .sys. The 32-bit VxD message server (msgsrv32) is a program that is able to load virtual device drivers (VxDs) at startup and then handle communication with the drivers. Additionally, the message server performs several background functions, including loading the Windows shell (such as Explorer.exe or Progman.exe). Another type of device drivers are .DRV drivers. These drivers are loaded in user-mode, and are commonly used to control devices such as multimedia devices. To provide access to these devices, a dynamic link library is required (such as MMSYSTEM.DLL). Windows 9x retains backwards compatibility with many drivers made for Windows 3.x and MS-DOS. Using MS-DOS drivers can limit performance and stability due to their use of conventional memory and need to run in real mode which requires the CPU to switch in and out of protected mode. Drivers written for Windows 9x/Windows Me are loaded into the same address space as the kernel. This means that drivers can by accident or design overwrite critical sections of the operating system. Doing this can lead to system crashes, freezes and disk corruption. Faulty operating system drivers were a source of instability for the operating system. Other monolithic and hybrid kernels, like Linux and Windows NT, are also susceptible to malfunctioning drivers impeding the kernel's operation. Often the software developers of drivers and applications had insufficient experience with creating programs for the 'new' system, thus causing many errors which have been generally described as "system errors" by users, even if the error is not caused by parts of Windows or DOS. Microsoft has repeatedly redesigned the Windows Driver architecture since the release of Windows 95 as a result. CPU and bus technologies Windows 9x has no native support for hyper-threading, Data Execution Prevention, symmetric multiprocessing, or multi-core processors. Windows 9x has no native support for SATA host bus adapters (and neither did Windows 2000 nor Windows XP), or USB drives (except Windows Me). There are, however, many SATA-I controllers for which Windows 98/Me drivers exist, and USB mass storage support has been added to Windows 95 OSR2 and Windows 98 through third party drivers. Hardware driver support for Windows 98/Me began to decline in 2005, most notably for motherboard chipsets and video cards. Early versions of Windows 95 had no support for USB or AGP acceleration. MS-DOS Windows 95 was able to reduce the role of MS-DOS in Windows much further than had been done in Windows 3.1x and earlier. According to Microsoft developer Raymond Chen, MS-DOS served two purposes in Windows 95: as the boot loader, and as the 16-bit legacy device driver layer. When Windows 95 started up, MS-DOS loaded, processed CONFIG.SYS, launched COMMAND.COM, ran AUTOEXEC.BAT and finally ran WIN.COM. The WIN.COM program used MS-DOS to load the virtual machine manager, read SYSTEM.INI, load the virtual device drivers, and then turn off any running copies of EMM386 and switch into protected mode. Once in protected mode, the virtual device drivers (VxDs) transferred all state information from MS-DOS to the 32-bit file system manager, and then shut off MS-DOS. These VxDs allow Windows 9x to interact with hardware resources directly, as providing low-level functionalities such as 32-bit disk access and memory management. All future file system operations would get routed to the 32-bit file system manager. In Windows Me, win.com was no longer executed during the startup process; instead it went directly to execute VMM32.VXD from IO.SYS. The second role of MS-DOS (as the 16-bit legacy device driver layer) was as a backward compatibility tool for running DOS programs in Windows. Many MS-DOS programs and device drivers interacted with DOS in a low-level way, for example, by patching low-level BIOS interrupts such as int 13h, the low-level disk I/O interrupt. When a program issued an int 21h call to access MS-DOS, the call would go first to the 32-bit file system manager, which would attempt to detect this sort of patching. If it detects that the program has tried to hook into DOS, it will jump back into the 16-bit code to let the hook run. A 16-bit driver called IFSMGR.SYS would previously have been loaded by CONFIG.SYS, the job of which was to hook MS-DOS first before the other drivers and programs got a chance, then jump from 16-bit code back into 32-bit code, when the DOS program had finished, to let the 32-bit file system manager continue its work. According to Windows developer Raymond Chen, "MS-DOS was just an extremely elaborate decoy. Any 16-bit drivers and programs would patch or hook what they thought was the real MS-DOS, but which was in reality just a decoy. If the 32-bit file system manager detected that somebody bought the decoy, it told the decoy to quack." MS-DOS Virtualization Windows 9x can run MS-DOS applications within itself using a method called "Virtualization", where an application is run on a Virtual DOS machine. MS-DOS Mode Windows 95 and Windows 98 also offer regressive support for DOS applications in the form of being able to boot into a native "DOS Mode" (MS-DOS can be booted without booting Windows, not putting the CPU in protected mode). Through Windows 9x's memory managers and other post-DOS improvements, the overall system performance and functionality is improved. This differs from the emulation used in Windows NT-based operating systems. Some old applications or games may not run properly in a DOS box within Windows and require real DOS Mode. Having a command line mode outside of the GUI also offers the ability to fix certain system errors without entering the GUI. For example, if a virus is active in GUI mode it can often be safely removed in DOS mode, by deleting its files, which are usually locked while infected in Windows. Similarly, corrupted registry files, system files or boot files can be restored from the command line. Windows 95 and Windows 98 can be started from DOS Mode by typing 'WIN' <enter> at the command prompt. However, the Recovery Console for Windows 2000, which as a version of Windows NT played a similar role in removing viruses. Because DOS was not designed for multitasking purposes, Windows versions such as 9x that are DOS-based lack File System security, such as file permissions. Further, if the user uses 16-bit DOS drivers, Windows can become unstable. Hard disk errors often plague the Windows 9x series. User interface Users can control a Windows 9x-based system through a command-line interface (or CLI), or a graphical user interface (or GUI). For desktop systems, the default mode is usually graphical user interface, where the CLI is available through MS-DOS windows. The GDI, which is a part of the Win32 and Win16 subsystems, is also a module that is loaded in user mode, unlike Windows NT where the GDI is loaded in kernel mode. Alpha compositing and therefore transparency effects, such as fade effects in menus, are not supported by the GDI in Windows 9x. On desktop machines, Windows Explorer is the default user interface, though a variety of additional Windows shell replacements exist. Other GUIs include LiteStep, bbLean and Program Manager. The GUI provides a means to control the placement and appearance of individual application windows, and interacts with the Window System. See also Comparison of operating systems Architecture of Windows 9x MS-DOS 7 References External links Computing platforms 9x Discontinued versions of Microsoft Windows

Operating System (OS)

Convergent Technologies Operating System The Convergent Technologies Operating System, also known variously as CTOS, BTOS and STARSYS, was a modular, message-passing, multiprocess-based operating system. Overview CTOS had many innovative features for its time. System access was controlled with a user password and Volume or disk passwords. If one knew the password, for example, for a volume, one could access any file or directory on that volume (hard disk). Each volume and directory were referenced with delimiters to identify them, and could be followed with a file name, depending on the operation, i.e. {Network Node}[VolumeName]<DirectoryName>FileName. It was possible to custom-link the operating system to add or delete features. CTOS supported a transparent peer-to-peer network carried over serial RS-422 cables (daisy-chain topology) and in later versions carried over twisted pair (star topology) with RS-422 adapters. Each workgroup (called a "cluster") was connected to a server (called a "master"). The workstations, normally diskless, were booted over the cluster network from the master, and could optionally be locally booted from attached hard drives. The Inter-process communication (IPC) is primarily based on the "request" and "respond" messaging foundation that enhanced the Enterprise Application Integration among services for both internal and external environments. Thus CTOS was well known for the message-based Microkernel Architecture. Applications are added as services to the main server. Each client consumes the services via its own mailbox called "exchange" and well-published message formats. The communication works on "request codes" that are owned by the service. The operating system maintains the exchanges, message queues, scheduling, control, message passing, etc., while the service manages the messages at its own exchange using "wait", "check", and "respond" macros. CTOS ran on Intel x86 computers, and could run concurrently with Windows NT on Unisys PC. The system API was presented to both high-level languages and assembly language. Programs The assembler was very advanced, with a Lisp-like pattern-matching macro facility unmatched by almost any other assembler before or since. There was an always-resident debugger. Most of the system programs were written in PL/M, an ALGOL-like language from Intel which compiled directly to object code without a runtime library. The word processor was one of the first screen-oriented editors with many high-powered features, such as multiple views of the same file, cut/copy/paste, unlimited undo/redo, no typing lost after a crash or power failure, user-selectable fonts, and much more. The spreadsheet allowed blocks of cells to be protected from editing or other user input. The BTOS version allowed scripts to be written that included opening the spreadsheet for user input, then automatically printing graphs based on the input data. The system shell was extensible, making it possible to define new commands. To get the parameters, the system would display the form which was to be filled out by the user. The input form had conventions for mandatory and optional input fields, which made it very easy to train new users. Usage Convergent Technologies' first product was the IWS (Integrated Workstation) based on the Intel 8086 processor, which had CTOS as its operating system. This was a modular operating system with built-in local area networking. CTOS supported multiple processes or threads, and message-based interprocess communication. Companies that licensed CTOS included Bull (STARSYS), and Burroughs (BTOS) who later merged with Sperry to become Unisys. Unisys was the single largest customer and acquired Convergent Technologies in 1988. At its peak, CTOS had over 800,000 users worldwide. CTOS is no longer marketed to new customers. Former major customers included police forces, banks, airlines, Nationwide Insurance, U-Haul, the U.S. Postal Service, the Drug Enforcement Administration, the U.S. Army and the United States Coast Guard. The Coast Guard used the operating system from approximately 1984 until 2000. In Australia, CTOS/BTOS was used by the Trade Practices Commission, NSW Auditor-General's, CSIRO, Commonwealth Electoral Office, Western Australia Prisons Department and many commercial banks. Diskless workstations (e.g., Bull) based on Convergent's NGEN used the Intel 80186 processor, a processor seldom used by standard PCs. Progress Software Corporation made a commercial database application for CTOS that was in 4GL. The United States Coast Guard used these databases for logistics administration for their vessels. There was a port of CorelDRAW for CTOS running the Presentation Manager. References External links The CTOS FAQ October 1999 CTOS Revealed, Byte, December 1994 Paul Mooney's CTOS Central The CTOS FAQ Picture Archive Exhuming CTOS: The Convergent Technologies Project, Nadia Ilyin Convergent archive at bitsavers.org Computer-related introductions in 1980 Discontinued operating systems Proprietary operating systems Unisys operating systems

Operating System (OS)

Open-source software Open-source software (OSS) is computer software that is released under a license in which the copyright holder grants users the rights to use, study, change, and distribute the software and its source code to anyone and for any purpose. Open-source software may be developed in a collaborative public manner. Open-source software is a prominent example of open collaboration, meaning any capable user is able to participate online in development, making the number of possible contributors indefinite. The ability to examine the code facilitates public trust in the software. Open-source software development can bring in diverse perspectives beyond those of a single company. A 2008 report by the Standish Group stated that adoption of open-source software models has resulted in savings of about $60 billion per year for consumers. Open source code can be used for studying and allows capable end users to adapt software to their personal needs in a similar way user scripts and custom style sheets allow for web sites, and eventually publish the modification as a fork for users with similar preferences, and directly submit possible improvements as pull requests. History End of 1990s: Foundation of the Open Source Initiative In the early days of computing, programmers and developers shared software in order to learn from each other and evolve the field of computing. Eventually, the open-source notion moved to the wayside of commercialization of software in the years 1970–1980. However, academics still often developed software collaboratively. Examples are Donald Knuth in 1979 with the TeX typesetting system and Richard Stallman in 1983 with the GNU operating system. In 1997, Eric Raymond published The Cathedral and the Bazaar, a reflective analysis of the hacker community and free-software principles. The paper received significant attention in early 1998, and was one factor in motivating Netscape Communications Corporation to release their popular Netscape Communicator Internet suite as free software. This source code subsequently became the basis behind SeaMonkey, Mozilla Firefox, Thunderbird and KompoZer. Netscape's act prompted Raymond and others to look into how to bring the Free Software Foundation's free software ideas and perceived benefits to the commercial software industry. They concluded that FSF's social activism was not appealing to companies like Netscape, and looked for a way to rebrand the free software movement to emphasize the business potential of sharing and collaborating on software source code. The new term they chose was "open source", which was soon adopted by Bruce Perens, publisher Tim O'Reilly, Linus Torvalds, and others. The Open Source Initiative was founded in February 1998 to encourage use of the new term and evangelize open-source principles. While the Open Source Initiative sought to encourage the use of the new term and evangelize the principles it adhered to, commercial software vendors found themselves increasingly threatened by the concept of freely distributed software and universal access to an application's source code. Microsoft executive Jim Allchin publicly stated in 2001 that "open source is an intellectual property destroyer. I can't imagine something that could be worse than this for the software business and the intellectual-property business." However, while Free and open-source software has historically played a role outside of the mainstream of private software development, companies as large as Microsoft have begun to develop official open-source presences on the Internet. IBM, Oracle, Google, and State Farm are just a few of the companies with a serious public stake in today's competitive open-source market. There has been a significant shift in the corporate philosophy concerning the development of FOSS. The free-software movement was launched in 1983. In 1998, a group of individuals advocated that the term free software should be replaced by open-source software (OSS) as an expression which is less ambiguous and more comfortable for the corporate world. Software developers may want to publish their software with an open-source license, so that anybody may also develop the same software or understand its internal functioning. With open-source software, generally, anyone is allowed to create modifications of it, port it to new operating systems and instruction set architectures, share it with others or, in some cases, market it. Scholars Casson and Ryan have pointed out several policy-based reasons for adoption of open source – in particular, the heightened value proposition from open source (when compared to most proprietary formats) in the following categories: Security Affordability Transparency Perpetuity Interoperability Flexibility Localization – particularly in the context of local governments (who make software decisions). Casson and Ryan argue that "governments have an inherent responsibility and fiduciary duty to taxpayers" which includes the careful analysis of these factors when deciding to purchase proprietary software or implement an open-source option. The Open Source Definition presents an open-source philosophy and further defines the terms of use, modification and redistribution of open-source software. Software licenses grant rights to users which would otherwise be reserved by copyright law to the copyright holder. Several open-source software licenses have qualified within the boundaries of the Open Source Definition. The most prominent and popular example is the GNU General Public License (GPL), which "allows free distribution under the condition that further developments and applications are put under the same licence", thus also free. The open source label came out of a strategy session held on April 7, 1998, in Palo Alto in reaction to Netscape's January 1998 announcement of a source code release for Navigator (as Mozilla). A group of individuals at the session included Tim O'Reilly, Linus Torvalds, Tom Paquin, Jamie Zawinski, Larry Wall, Brian Behlendorf, Sameer Parekh, Eric Allman, Greg Olson, Paul Vixie, John Ousterhout, Guido van Rossum, Philip Zimmermann, John Gilmore and Eric S. Raymond. They used the opportunity before the release of Navigator's source code to clarify a potential confusion caused by the ambiguity of the word "free" in English. Many people claimed that the birth of the Internet, since 1969, started the open-source movement, while others do not distinguish between open-source and free software movements. The Free Software Foundation (FSF), started in 1985, intended the word "free" to mean freedom to distribute (or "free as in free speech") and not freedom from cost (or "free as in free beer"). Since a great deal of free software already was (and still is) free of charge, such free software became associated with zero cost, which seemed anti-commercial. The Open Source Initiative (OSI) was formed in February 1998 by Eric Raymond and Bruce Perens. With at least 20 years of evidence from case histories of closed software development versus open development already provided by the Internet developer community, the OSI presented the "open source" case to commercial businesses, like Netscape. The OSI hoped that the use of the label "open source", a term suggested by Christine Peterson of the Foresight Institute at the strategy session, would eliminate ambiguity, particularly for individuals who perceive "free software" as anti-commercial. They sought to bring a higher profile to the practical benefits of freely available source code, and they wanted to bring major software businesses and other high-tech industries into open source. Perens attempted to register "open source" as a service mark for the OSI, but that attempt was impractical by trademark standards. Meanwhile, due to the presentation of Raymond's paper to the upper management at Netscape—Raymond only discovered when he read the press release, and was called by Netscape CEO Jim Barksdale's PA later in the day—Netscape released its Navigator source code as open source, with favorable results. Definitions The Open Source Initiative's (OSI) definition is recognized by several governments internationally as the standard or de facto definition. In addition, many of the world's largest open-source-software projects and contributors, including Debian, Drupal Association, FreeBSD Foundation, Linux Foundation, OpenSUSE Foundation, Mozilla Foundation, Wikimedia Foundation, Wordpress Foundation have committed to upholding the OSI's mission and Open Source Definition through the OSI Affiliate Agreement. OSI uses The Open Source Definition to determine whether it considers a software license open source. The definition was based on the Debian Free Software Guidelines, written and adapted primarily by Perens. Perens did not base his writing on the "four freedoms" from the Free Software Foundation (FSF), which were only widely available later. Under Perens' definition, open source is a broad software license that makes source code available to the general public with relaxed or non-existent restrictions on the use and modification of the code. It is an explicit "feature" of open source that it puts very few restrictions on the use or distribution by any organization or user, in order to enable the rapid evolution of the software. Despite initially accepting it, Richard Stallman of the FSF now flatly opposes the term "Open Source" being applied to what they refer to as "free software". Although he agrees that the two terms describe "almost the same category of software", Stallman considers equating the terms incorrect and misleading. Stallman also opposes the professed pragmatism of the Open Source Initiative, as he fears that the free software ideals of freedom and community are threatened by compromising on the FSF's idealistic standards for software freedom. The FSF considers free software to be a subset of open-source software, and Richard Stallman explained that DRM software, for example, can be developed as open source, despite that it does not give its users freedom (it restricts them), and thus doesn't qualify as free software. Open-source software licensing When an author contributes code to an open-source project (e.g., Apache.org) they do so under an explicit license (e.g., the Apache Contributor License Agreement) or an implicit license (e.g. the open-source license under which the project is already licensing code). Some open-source projects do not take contributed code under a license, but actually require joint assignment of the author's copyright in order to accept code contributions into the project. Examples of free software license / open-source licenses include Apache License, BSD license, GNU General Public License, GNU Lesser General Public License, MIT License, Eclipse Public License and Mozilla Public License. The proliferation of open-source licenses is a negative aspect of the open-source movement because it is often difficult to understand the legal implications of the differences between licenses. With more than 180,000 open-source projects available and more than 1400 unique licenses, the complexity of deciding how to manage open-source use within "closed-source" commercial enterprises has dramatically increased. Some are home-grown, while others are modeled after mainstream FOSS licenses such as Berkeley Software Distribution ("BSD"), Apache, MIT-style (Massachusetts Institute of Technology), or GNU General Public License ("GPL"). In view of this, open-source practitioners are starting to use classification schemes in which FOSS licenses are grouped (typically based on the existence and obligations imposed by the copyleft provision; the strength of the copyleft provision). An important legal milestone for the open source / free software movement was passed in 2008, when the US federal appeals court ruled that free software licenses definitely do set legally binding conditions on the use of copyrighted work, and they are therefore enforceable under existing copyright law. As a result, if end-users violate the licensing conditions, their license disappears, meaning they are infringing copyright. Despite this licensing risk, most commercial software vendors are using open-source software in commercial products while fulfilling the license terms, e.g. leveraging the Apache license. Certifications Certification can help to build user confidence. Certification could be applied to the simplest component, to a whole software system. The United Nations University International Institute for Software Technology, initiated a project known as "The Global Desktop Project". This project aims to build a desktop interface that every end-user is able to understand and interact with, thus crossing the language and cultural barriers. The project would improve developing nations' access to information systems. UNU/IIST hopes to achieve this without any compromise in the quality of the software by introducing certifications. Open-source software development Development model In his 1997 essay The Cathedral and the Bazaar, open-source evangelist Eric S. Raymond suggests a model for developing OSS known as the bazaar model. Raymond likens the development of software by traditional methodologies to building a cathedral, "carefully crafted by individual wizards or small bands of mages working in splendid isolation". He suggests that all software should be developed using the bazaar style, which he described as "a great babbling bazaar of differing agendas and approaches." In the traditional model of development, which he called the cathedral model, development takes place in a centralized way. Roles are clearly defined. Roles include people dedicated to designing (the architects), people responsible for managing the project, and people responsible for implementation. Traditional software engineering follows the cathedral model. The bazaar model, however, is different. In this model, roles are not clearly defined. Gregorio Robles suggests that software developed using the bazaar model should exhibit the following patterns: Users should be treated as co-developers The users are treated like co-developers and so they should have access to the source code of the software. Furthermore, users are encouraged to submit additions to the software, code fixes for the software, bug reports, documentation, etc. Having more co-developers increases the rate at which the software evolves. Linus's law states, "Given enough eyeballs all bugs are shallow." This means that if many users view the source code, they will eventually find all bugs and suggest how to fix them. Note that some users have advanced programming skills, and furthermore, each user's machine provides an additional testing environment. This new testing environment offers the ability to find and fix a new bug. Early releases The first version of the software should be released as early as possible so as to increase one's chances of finding co-developers early. Frequent integration Code changes should be integrated (merged into a shared code base) as often as possible so as to avoid the overhead of fixing a large number of bugs at the end of the project life cycle. Some open-source projects have nightly builds where integration is done automatically on a daily basis. Several versions There should be at least two versions of the software. There should be a buggier version with more features and a more stable version with fewer features. The buggy version (also called the development version) is for users who want the immediate use of the latest features, and are willing to accept the risk of using code that is not yet thoroughly tested. The users can then act as co-developers, reporting bugs and providing bug fixes. High modularization The general structure of the software should be modular allowing for parallel development on independent components. Dynamic decision-making structure There is a need for a decision-making structure, whether formal or informal, that makes strategic decisions depending on changing user requirements and other factors. Compare with extreme programming. Data suggests, however, that OSS is not quite as democratic as the bazaar model suggests. An analysis of five billion bytes of free/open-source code by 31,999 developers shows that 74% of the code was written by the most active 10% of authors. The average number of authors involved in a project was 5.1, with the median at 2. Advantages and disadvantages Open-source software is usually easier to obtain than proprietary software, often resulting in increased use. Additionally, the availability of an open-source implementation of a standard can increase adoption of that standard. It has also helped to build developer loyalty as developers feel empowered and have a sense of ownership of the end product. Moreover, lower costs of marketing and logistical services are needed for OSS. It is a good tool to promote a company's image, including its commercial products. The OSS development approach has helped produce reliable, high quality software quickly and inexpensively. Open-source development offers the potential for a more flexible technology and quicker innovation. It is said to be more reliable since it typically has thousands of independent programmers testing and fixing bugs of the software. Open source is not dependent on the company or author that originally created it. Even if the company fails, the code continues to exist and be developed by its users. Also, it uses open standards accessible to everyone; thus, it does not have the problem of incompatible formats that may exist in proprietary software. It is flexible because modular systems allow programmers to build custom interfaces, or add new abilities to it and it is innovative since open-source programs are the product of collaboration among a large number of different programmers. The mix of divergent perspectives, corporate objectives, and personal goals speeds up innovation. Moreover, free software can be developed in accordance with purely technical requirements. It does not require thinking about commercial pressure that often degrades the quality of the software. Commercial pressures make traditional software developers pay more attention to customers' requirements than to security requirements, since such features are somewhat invisible to the customer. It is sometimes said that the open-source development process may not be well defined and the stages in the development process, such as system testing and documentation may be ignored. However this is only true for small (mostly single programmer) projects. Larger, successful projects do define and enforce at least some rules as they need them to make the teamwork possible. In the most complex projects these rules may be as strict as reviewing even minor change by two independent developers. Not all OSS initiatives have been successful; for example, SourceXchange and Eazel. Software experts and researchers who are not convinced by open source's ability to produce quality systems identify the unclear process, the late defect discovery and the lack of any empirical evidence as the most important problems (collected data concerning productivity and quality). It is also difficult to design a commercially sound business model around the open-source paradigm. Consequently, only technical requirements may be satisfied and not the ones of the market. In terms of security, open source may allow hackers to know about the weaknesses or loopholes of the software more easily than closed-source software. It depends on control mechanisms in order to create effective performance of autonomous agents who participate in virtual organizations. Development tools In OSS development, tools are used to support the development of the product and the development process itself. Revision control systems such as Concurrent Versions System (CVS) and later Subversion (SVN) and Git are examples of tools, often themselves open source, help manage the source code files and the changes to those files for a software project. The projects are frequently stored in "repositories" that are hosted and published on source-code-hosting facilities such as Launchpad, GitHub, GitLab, and SourceForge. Open-source projects are often loosely organized with "little formalised process modelling or support", but utilities such as issue trackers are often used to organize open-source software development. Commonly used bugtrackers include Bugzilla and Redmine. Tools such as mailing lists and IRC provide means of coordination among developers. Centralized code hosting sites also have social features that allow developers to communicate. Organizations Some of the "more prominent organizations" involved in OSS development include the Apache Software Foundation, creators of the Apache web server; the Linux Foundation, a nonprofit which employed Linus Torvalds, the creator of the Linux operating system kernel; the Eclipse Foundation, home of the Eclipse software development platform; the Debian Project, creators of the influential Debian GNU/Linux distribution; the Mozilla Foundation, home of the Firefox web browser; and OW2, European-born community developing open-source middleware. New organizations tend to have a more sophisticated governance model and their membership is often formed by legal entity members. Open Source Software Institute is a membership-based, non-profit (501 (c)(6)) organization established in 2001 that promotes the development and implementation of open source software solutions within US Federal, state and local government agencies. OSSI's efforts have focused on promoting adoption of open-source software programs and policies within Federal Government and Defense and Homeland Security communities. Open Source for America is a group created to raise awareness in the United States Federal Government about the benefits of open-source software. Their stated goals are to encourage the government's use of open source software, participation in open-source software projects, and incorporation of open-source community dynamics to increase government transparency. Mil-OSS is a group dedicated to the advancement of OSS use and creation in the military. Funding Comparisons with other software licensing/development models Closed source / proprietary software The debate over open source vs. closed source (alternatively called proprietary software) is sometimes heated. The top four reasons (as provided by Open Source Business Conference survey) individuals or organizations choose open-source software are: lower cost security no vendor 'lock in' better quality Since innovative companies no longer rely heavily on software sales, proprietary software has become less of a necessity. As such, things like open-source content management system—or CMS—deployments are becoming more commonplace. In 2009, the US White House switched its CMS system from a proprietary system to Drupal open source CMS. Further, companies like Novell (who traditionally sold software the old-fashioned way) continually debate the benefits of switching to open-source availability, having already switched part of the product offering to open source code. In this way, open-source software provides solutions to unique or specific problems. As such, it is reported that 98% of enterprise-level companies use open-source software offerings in some capacity. With this market shift, more critical systems are beginning to rely on open-source offerings, allowing greater funding (such as US Department of Homeland Security grants) to help "hunt for security bugs." According to a pilot study of organizations adopting (or not adopting) OSS, the following factors of statistical significance were observed in the manager's beliefs: (a) attitudes toward outcomes, (b) the influences and behaviors of others, and (c) their ability to act. Proprietary source distributors have started to develop and contribute to the open-source community due to the market share shift, doing so by the need to reinvent their models in order to remain competitive. Many advocates argue that open-source software is inherently safer because any person can view, edit, and change code. A study of the Linux source code has 0.17 bugs per 1000 lines of code while proprietary software generally scores 20–30 bugs per 1000 lines. Free software According to the Free software movement's leader, Richard Stallman, the main difference is that by choosing one term over the other (i.e. either "open source" or "free software") one lets others know about what one's goals are: "Open source is a development methodology; free software is a social movement." Nevertheless, there is significant overlap between open source software and free software. The FSF said that the term "open source" fosters an ambiguity of a different kind such that it confuses the mere availability of the source with the freedom to use, modify, and redistribute it. On the other hand, the "free software" term was criticized for the ambiguity of the word "free" as "available at no cost", which was seen as discouraging for business adoption, and for the historical ambiguous usage of the term. Developers have used the alternative terms Free and Open Source Software (FOSS), or Free/Libre and Open Source Software (FLOSS), consequently, to describe open-source software that is also free software. While the definition of open source software is very similar to the FSF's free software definition it was based on the Debian Free Software Guidelines, written and adapted primarily by Bruce Perens with input from Eric S. Raymond and others. The term "open source" was originally intended to be trademarkable; however, the term was deemed too descriptive, so no trademark exists. The OSI would prefer that people treat open source as if it were a trademark, and use it only to describe software licensed under an OSI approved license. OSI Certified is a trademark licensed only to people who are distributing software licensed under a license listed on the Open Source Initiative's list. Open-source versus source-available Although the OSI definition of "open-source software" is widely accepted, a small number of people and organizations use the term to refer to software where the source is available for viewing, but which may not legally be modified or redistributed. Such software is more often referred to as source-available, or as shared source, a term coined by Microsoft in 2001. While in 2007 two of Microsoft's Shared Source Initiative licenses were certified by the OSI, most licenses from the SSI program are still source-available only. Open-sourcing Open-sourcing is the act of propagating the open source movement, most often referring to releasing previously proprietary software under an open source/free software license, but it may also refer programming Open Source software or installing Open Source software. Notable software packages, previously proprietary, which have been open sourced include: Netscape Navigator, the code of which became the basis of the Mozilla and Mozilla Firefox web browsers StarOffice, which became the base of the OpenOffice.org office suite and LibreOffice Global File System, was originally GPL'd, then made proprietary in 2001(?), but in 2004 was re-GPL'd. SAP DB, which has become MaxDB, and is now distributed (and owned) by MySQL AB InterBase database, which was open sourced by Borland in 2000 and presently exists as a commercial product and an open-source fork (Firebird) Before changing the license of software, distributors usually audit the source code for third party licensed code which they would have to remove or obtain permission for its relicense. Backdoors and other malware should also be removed as they may easily be discovered after release of the code. Current applications and adoption Widely used open-source software Open-source software projects are built and maintained by a network of volunteer programmers and are widely used in free as well as commercial products. Prime examples of open-source products are the Apache HTTP Server, the e-commerce platform osCommerce, internet browsers Mozilla Firefox and Chromium (the project where the vast majority of development of the freeware Google Chrome is done) and the full office suite LibreOffice. One of the most successful open-source products is the GNU/Linux operating system, an open-source Unix-like operating system, and its derivative Android, an operating system for mobile devices. In some industries, open-source software is the norm. Extensions for non-software use While the term "open source" applied originally only to the source code of software, it is now being applied to many other areas such as Open source ecology, a movement to decentralize technologies so that any human can use them. However, it is often misapplied to other areas that have different and competing principles, which overlap only partially. The same principles that underlie open-source software can be found in many other ventures, such as open-source hardware, Wikipedia, and open-access publishing. Collectively, these principles are known as open source, open content, and open collaboration: "any system of innovation or production that relies on goal-oriented yet loosely coordinated participants, who interact to create a product (or service) of economic value, which they make available to contributors and non-contributors alike." This "culture" or ideology takes the view that the principles apply more generally to facilitate concurrent input of different agendas, approaches, and priorities, in contrast with more centralized models of development such as those typically used in commercial companies. See also References Further reading Coleman, E. Gabriella. Coding Freedom: The Ethics and Aesthetics of Hacking (Princeton UP, 2012) Understanding FOSS | editor = Sampathkumar Coimbatore India Benkler, Yochai (2002), "Coase's Penguin, or, Linux and The Nature of the Firm." Yale Law Journal 112.3 (Dec 2002): p367(78) (in Adobe pdf format) Lerner, J. & Tirole, J. (2002): 'Some simple economics on open source', Journal of Industrial Economics 50(2), p 197–234 Rossi, M. A. (2006): Decoding the free/open-source software puzzle: A survey of theoretical and empirical contributions, in J. Bitzer P. Schröder, eds, 'The Economics of Open Source Software Development', p 15–55. Open Sources: Voices from the Open Source Revolution — an online book containing essays from prominent members of the open-source community Berry, D M (2004). The Contestation of Code: A Preliminary Investigation into the Discourse of the Free Software and Open Software Movement, Critical Discourse Studies, Volume 1(1). Sustainable Open Source, a Confluence article providing guidelines for fair participation in the open source ecosystem, by Radovan Semancik External links The Open Source Initiative's definition of open source Free / Open Source Research Community — Many online research papers about Open Source Free software Software licenses

Operating System (OS)

Unix Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and others. Initially intended for use inside the Bell System, AT&T licensed Unix to outside parties in the late 1970s, leading to a variety of both academic and commercial Unix variants from vendors including University of California, Berkeley (BSD), Microsoft (Xenix), Sun Microsystems (SunOS/Solaris), HP/HPE (HP-UX), and IBM (AIX). In the early 1990s, AT&T sold its rights in Unix to Novell, which then sold its Unix business to the Santa Cruz Operation (SCO) in 1995. The UNIX trademark passed to The Open Group, an industry consortium founded in 1996, which allows the use of the mark for certified operating systems that comply with the Single UNIX Specification (SUS). However, Novell continues to own the Unix copyrights, which the SCO Group, Inc. v. Novell, Inc. court case (2010) confirmed. Unix systems are characterized by a modular design that is sometimes called the "Unix philosophy". According to this philosophy, the operating system should provide a set of simple tools, each of which performs a limited, well-defined function. A unified and inode-based filesystem (the Unix filesystem) and an inter-process communication mechanism known as "pipes" serve as the main means of communication, and a shell scripting and command language (the Unix shell) is used to combine the tools to perform complex workflows. Unix distinguishes itself from its predecessors as the first portable operating system: almost the entire operating system is written in the C programming language, which allows Unix to operate on numerous platforms. Overview Unix was originally meant to be a convenient platform for programmers developing software to be run on it and on other systems, rather than for non-programmers. The system grew larger as the operating system started spreading in academic circles, and as users added their own tools to the system and shared them with colleagues. At first, Unix was not designed to be portable or for multi-tasking. Later, Unix gradually gained portability, multi-tasking and multi-user capabilities in a time-sharing configuration. Unix systems are characterized by various concepts: the use of plain text for storing data; a hierarchical file system; treating devices and certain types of inter-process communication (IPC) as files; and the use of a large number of software tools, small programs that can be strung together through a command-line interpreter using pipes, as opposed to using a single monolithic program that includes all of the same functionality. These concepts are collectively known as the "Unix philosophy". Brian Kernighan and Rob Pike summarize this in The Unix Programming Environment as "the idea that the power of a system comes more from the relationships among programs than from the programs themselves". By the early 1980s, users began seeing Unix as a potential universal operating system, suitable for computers of all sizes. The Unix environment and the client–server program model were essential elements in the development of the Internet and the reshaping of computing as centered in networks rather than in individual computers. Both Unix and the C programming language were developed by AT&T and distributed to government and academic institutions, which led to both being ported to a wider variety of machine families than any other operating system. The Unix operating system consists of many libraries and utilities along with the master control program, the kernel. The kernel provides services to start and stop programs, handles the file system and other common "low-level" tasks that most programs share, and schedules access to avoid conflicts when programs try to access the same resource or device simultaneously. To mediate such access, the kernel has special rights, reflected in the distinction of kernel space from user space, the latter being a priority realm where most application programs operate. History The origins of Unix date back to the mid-1960s when the Massachusetts Institute of Technology, Bell Labs, and General Electric were developing Multics, a time-sharing operating system for the GE-645 mainframe computer. Multics featured several innovations, but also presented severe problems. Frustrated by the size and complexity of Multics, but not by its goals, individual researchers at Bell Labs started withdrawing from the project. The last to leave were Ken Thompson, Dennis Ritchie, Douglas McIlroy, and Joe Ossanna, who decided to reimplement their experiences in a new project of smaller scale. This new operating system was initially without organizational backing, and also without a name. The new operating system was a single-tasking system. In 1970, the group coined the name Unics for Uniplexed Information and Computing Service as a pun on Multics, which stood for Multiplexed Information and Computer Services. Brian Kernighan takes credit for the idea, but adds that "no one can remember" the origin of the final spelling Unix. Dennis Ritchie, Doug McIlroy, and Peter G. Neumann also credit Kernighan. The operating system was originally written in assembly language, but in 1973, Version 4 Unix was rewritten in C. Version 4 Unix, however, still had many PDP-11 dependent codes, and was not suitable for porting. The first port to another platform was made five years later (1978) for the Interdata 8/32. In 1974, Ken Robinson of the Department of Computer Science at University of New South Wales (UNSW) in Australia requested a copy of Unix for their PDP-11/40 minicomputer from Dennis Ritchie at Bell Labs. This 1975 installation made UNSW the first university outside the United States to run Unix. Bell Labs produced several versions of Unix that are collectively referred to as Research Unix. In 1975, the first source license for UNIX was sold to Donald B. Gillies at the University of Illinois Urbana–Champaign Department of Computer Science (UIUC). UIUC graduate student Greg Chesson, who had worked on the Unix kernel at Bell Labs, was instrumental in negotiating the terms of the license. During the late 1970s and early 1980s, the influence of Unix in academic circles led to large-scale adoption of Unix (BSD and System V) by commercial startups, which in turn led to Unix fragmenting into multiple, similar but often slightly mutually-incompatible systems including DYNIX, HP-UX, SunOS/Solaris, AIX, and Xenix. In the late 1980s, AT&T Unix System Laboratories and Sun Microsystems developed System V Release 4 (SVR4), which was subsequently adopted by many commercial Unix vendors. In the 1990s, Unix and Unix-like systems grew in popularity and became the operating system of choice for over 90% of the world's top 500 fastest supercomputers, as BSD and Linux distributions were developed through collaboration by a worldwide network of programmers. In 2000, Apple released Darwin, also a Unix system, which became the core of the Mac OS X operating system, later renamed macOS. Unix operating systems are widely used in modern servers, workstations, and mobile devices. Standards In the late 1980s, an open operating system standardization effort now known as POSIX provided a common baseline for all operating systems; IEEE based POSIX around the common structure of the major competing variants of the Unix system, publishing the first POSIX standard in 1988. In the early 1990s, a separate but very similar effort was started by an industry consortium, the Common Open Software Environment (COSE) initiative, which eventually became the Single UNIX Specification (SUS) administered by The Open Group. Starting in 1998, the Open Group and IEEE started the Austin Group, to provide a common definition of POSIX and the Single UNIX Specification, which, by 2008, had become the Open Group Base Specification. In 1999, in an effort towards compatibility, several Unix system vendors agreed on SVR4's Executable and Linkable Format (ELF) as the standard for binary and object code files. The common format allows substantial binary compatibility among different Unix systems operating on the same CPU architecture. The Filesystem Hierarchy Standard was created to provide a reference directory layout for Unix-like operating systems; it has mainly been used in Linux. Components The Unix system is composed of several components that were originally packaged together. By including the development environment, libraries, documents and the portable, modifiable source code for all of these components, in addition to the kernel of an operating system, Unix was a self-contained software system. This was one of the key reasons it emerged as an important teaching and learning tool and has had such a broad influence. The inclusion of these components did not make the system large the original V7 UNIX distribution, consisting of copies of all of the compiled binaries plus all of the source code and documentation occupied less than 10 MB and arrived on a single nine-track magnetic tape. The printed documentation, typeset from the online sources, was contained in two volumes. The names and filesystem locations of the Unix components have changed substantially across the history of the system. Nonetheless, the V7 implementation is considered by many to have the canonical early structure: Kernel source code in /usr/sys, composed of several sub-components: conf configuration and machine-dependent parts, including boot code dev device drivers for control of hardware (and some pseudo-hardware) sys operating system "kernel", handling memory management, process scheduling, system calls, etc. h header files, defining key structures within the system and important system-specific invariables Development environment early versions of Unix contained a development environment sufficient to recreate the entire system from source code: ed text editor, for creating source code files cc C language compiler (first appeared in V3 Unix) as machine-language assembler for the machine ld linker, for combining object files lib object-code libraries (installed in /lib or /usr/lib). libc, the system library with C run-time support, was the primary library, but there have always been additional libraries for things such as mathematical functions (libm) or database access. V7 Unix introduced the first version of the modern "Standard I/O" library stdio as part of the system library. Later implementations increased the number of libraries significantly. make build manager (introduced in PWB/UNIX), for effectively automating the build process include header files for software development, defining standard interfaces and system invariants Other languages V7 Unix contained a Fortran-77 compiler, a programmable arbitrary-precision calculator (bc, dc), and the awk scripting language; later versions and implementations contain many other language compilers and toolsets. Early BSD releases included Pascal tools, and many modern Unix systems also include the GNU Compiler Collection as well as or instead of a proprietary compiler system. Other tools including an object-code archive manager (ar), symbol-table lister (nm), compiler-development tools (e.g. lex & yacc), and debugging tools. Commands Unix makes little distinction between commands (user-level programs) for system operation and maintenance (e.g. cron), commands of general utility (e.g. grep), and more general-purpose applications such as the text formatting and typesetting package. Nonetheless, some major categories are: sh the "shell" programmable command-line interpreter, the primary user interface on Unix before window systems appeared, and even afterward (within a "command window"). Utilities the core toolkit of the Unix command set, including cp, ls, grep, find and many others. Subcategories include: System utilities administrative tools such as mkfs, fsck, and many others. User utilities environment management tools such as passwd, kill, and others. Document formatting Unix systems were used from the outset for document preparation and typesetting systems, and included many related programs such as nroff, troff, tbl, eqn, refer, and pic. Some modern Unix systems also include packages such as TeX and Ghostscript. Graphics the plot subsystem provided facilities for producing simple vector plots in a device-independent format, with device-specific interpreters to display such files. Modern Unix systems also generally include X11 as a standard windowing system and GUI, and many support OpenGL. Communications early Unix systems contained no inter-system communication, but did include the inter-user communication programs mail and write. V7 introduced the early inter-system communication system UUCP, and systems beginning with BSD release 4.1c included TCP/IP utilities. Documentation Unix was the first operating system to include all of its documentation online in machine-readable form. The documentation included: man manual pages for each command, library component, system call, header file, etc. doc longer documents detailing major subsystems, such as the C language and troff Impact The Unix system had a significant impact on other operating systems. It achieved its reputation by its interactivity, by providing the software at a nominal fee for educational use, by running on inexpensive hardware, and by being easy to adapt and move to different machines. Unix was originally written in assembly language, but was soon rewritten in C, a high-level programming language. Although this followed the lead of CTSS, Multics and Burroughs MCP, it was Unix that popularized the idea. Unix had a drastically simplified file model compared to many contemporary operating systems: treating all kinds of files as simple byte arrays. The file system hierarchy contained machine services and devices (such as printers, terminals, or disk drives), providing a uniform interface, but at the expense of occasionally requiring additional mechanisms such as ioctl and mode flags to access features of the hardware that did not fit the simple "stream of bytes" model. The Plan 9 operating system pushed this model even further and eliminated the need for additional mechanisms. Unix also popularized the hierarchical file system with arbitrarily nested subdirectories, originally introduced by Multics. Other common operating systems of the era had ways to divide a storage device into multiple directories or sections, but they had a fixed number of levels, often only one level. Several major proprietary operating systems eventually added recursive subdirectory capabilities also patterned after Multics. DEC's RSX-11M's "group, user" hierarchy evolved into OpenVMS directories, CP/M's volumes evolved into MS-DOS 2.0+ subdirectories, and HP's MPE group.account hierarchy and IBM's SSP and OS/400 library systems were folded into broader POSIX file systems. Making the command interpreter an ordinary user-level program, with additional commands provided as separate programs, was another Multics innovation popularized by Unix. The Unix shell used the same language for interactive commands as for scripting (shell scripts – there was no separate job control language like IBM's JCL). Since the shell and OS commands were "just another program", the user could choose (or even write) their own shell. New commands could be added without changing the shell itself. Unix's innovative command-line syntax for creating modular chains of producer-consumer processes (pipelines) made a powerful programming paradigm (coroutines) widely available. Many later command-line interpreters have been inspired by the Unix shell. A fundamental simplifying assumption of Unix was its focus on newline-delimited text for nearly all file formats. There were no "binary" editors in the original version of Unix – the entire system was configured using textual shell command scripts. The common denominator in the I/O system was the byte – unlike "record-based" file systems. The focus on text for representing nearly everything made Unix pipes especially useful and encouraged the development of simple, general tools that could be easily combined to perform more complicated ad hoc tasks. The focus on text and bytes made the system far more scalable and portable than other systems. Over time, text-based applications have also proven popular in application areas, such as printing languages (PostScript, ODF), and at the application layer of the Internet protocols, e.g., FTP, SMTP, HTTP, SOAP, and SIP. Unix popularized a syntax for regular expressions that found widespread use. The Unix programming interface became the basis for a widely implemented operating system interface standard (POSIX, see above). The C programming language soon spread beyond Unix, and is now ubiquitous in systems and applications programming. Early Unix developers were important in bringing the concepts of modularity and reusability into software engineering practice, spawning a "software tools" movement. Over time, the leading developers of Unix (and programs that ran on it) established a set of cultural norms for developing software, norms which became as important and influential as the technology of Unix itself; this has been termed the Unix philosophy. The TCP/IP networking protocols were quickly implemented on the Unix versions widely used on relatively inexpensive computers, which contributed to the Internet explosion of worldwide real-time connectivity, and which formed the basis for implementations on many other platforms. The Unix policy of extensive on-line documentation and (for many years) ready access to all system source code raised programmer expectations, and contributed to the launch of the free software movement in 1983. Free Unix and Unix-like variants In 1983, Richard Stallman announced the GNU (short for "GNU's Not Unix") project, an ambitious effort to create a free software Unix-like system; "free" in the sense that everyone who received a copy would be free to use, study, modify, and redistribute it. The GNU project's own kernel development project, GNU Hurd, had not yet produced a working kernel, but in 1991 Linus Torvalds released the Linux kernel as free software under the GNU General Public License. In addition to their use in the GNU operating system, many GNU packages – such as the GNU Compiler Collection (and the rest of the GNU toolchain), the GNU C library and the GNU core utilities – have gone on to play central roles in other free Unix systems as well. Linux distributions, consisting of the Linux kernel and large collections of compatible software have become popular both with individual users and in business. Popular distributions include Red Hat Enterprise Linux, Fedora, SUSE Linux Enterprise, openSUSE, Debian, Ubuntu, Linux Mint, Mandriva Linux, Slackware Linux, Arch Linux and Gentoo. A free derivative of BSD Unix, 386BSD, was released in 1992 and led to the NetBSD and FreeBSD projects. With the 1994 settlement of a lawsuit brought against the University of California and Berkeley Software Design Inc. (USL v. BSDi) by Unix System Laboratories, it was clarified that Berkeley had the right to distribute BSD Unix for free if it so desired. Since then, BSD Unix has been developed in several different product branches, including OpenBSD and DragonFly BSD. Linux and BSD are increasingly filling the market needs traditionally served by proprietary Unix operating systems, as well as expanding into new markets such as the consumer desktop and mobile and embedded devices. Because of the modular design of the Unix model, sharing components is relatively common; consequently, most or all Unix and Unix-like systems include at least some BSD code, and some systems also include GNU utilities in their distributions. In a 1999 interview, Dennis Ritchie voiced his opinion that Linux and BSD operating systems are a continuation of the basis of the Unix design, and are derivatives of Unix: In the same interview, he states that he views both Unix and Linux as "the continuation of ideas that were started by Ken and me and many others, many years ago". OpenSolaris was the free software counterpart to Solaris developed by Sun Microsystems, which included a CDDL-licensed kernel and a primarily GNU userland. However, Oracle discontinued the project upon their acquisition of Sun, which prompted a group of former Sun employees and members of the OpenSolaris community to fork OpenSolaris into the illumos kernel. As of 2014, illumos remains the only active open-source System V derivative. ARPANET In May 1975, RFC 681 described the development of Network Unix by the Center for Advanced Computation at the University of Illinois Urbana-Champaign. The Unix system was said to "present several interesting capabilities as an ARPANET mini-host". At the time, Unix required a license from Bell Telephone Laboratories that cost US$20,000 for non-university institutions, while universities could obtain a license for a nominal fee of $150. It was noted that Bell was "open to suggestions" for an ARPANET-wide license. The RFC specifically mentions that Unix "offers powerful local processing facilities in terms of user programs, several compilers, an editor based on QED, a versatile document preparation system, and an efficient file system featuring sophisticated access control, mountable and de-mountable volumes, and a unified treatment of peripherals as special files." The latter permitted the Network Control Program (NCP) to be integrated within the Unix file system, treating network connections as special files that could be accessed through standard Unix I/O calls, which included the added benefit of closing all connections on program exit, should the user neglect to do so. The modular design of Unix allowed them "to minimize the amount of code added to the basic Unix kernel", with much of the NCP code in a swappable user process, running only when needed. Branding In October 1993, Novell, the company that owned the rights to the Unix System V source at the time, transferred the trademarks of Unix to the X/Open Company (now The Open Group), and in 1995 sold the related business operations to Santa Cruz Operation (SCO). Whether Novell also sold the copyrights to the actual software was the subject of a federal lawsuit in 2006, SCO v. Novell, which Novell won. The case was appealed, but on August 30, 2011, the United States Court of Appeals for the Tenth Circuit affirmed the trial decisions, closing the case. Unix vendor SCO Group Inc. accused Novell of slander of title. The present owner of the trademark UNIX is The Open Group, an industry standards consortium. Only systems fully compliant with and certified to the Single UNIX Specification qualify as "UNIX" (others are called "Unix-like"). By decree of The Open Group, the term "UNIX" refers more to a class of operating systems than to a specific implementation of an operating system; those operating systems which meet The Open Group's Single UNIX Specification should be able to bear the UNIX 98 or UNIX 03 trademarks today, after the operating system's vendor pays a substantial certification fee and annual trademark royalties to The Open Group. Systems that have been licensed to use the UNIX trademark include AIX, EulerOS, HP-UX, Inspur K-UX, IRIX, macOS, Solaris, Tru64 UNIX (formerly "Digital UNIX", or OSF/1), and z/OS. Notably, EulerOS and Inspur K-UX are Linux distributions certified as UNIX 03 compliant. Sometimes a representation like Un*x, *NIX, or *N?X is used to indicate all operating systems similar to Unix. This comes from the use of the asterisk (*) and the question mark characters as wildcard indicators in many utilities. This notation is also used to describe other Unix-like systems that have not met the requirements for UNIX branding from the Open Group. The Open Group requests that UNIX is always used as an adjective followed by a generic term such as system to help avoid the creation of a genericized trademark. Unix was the original formatting, but the usage of UNIX remains widespread because it was once typeset in small caps (Unix). According to Dennis Ritchie, when presenting the original Unix paper to the third Operating Systems Symposium of the American Association for Computing Machinery (ACM), "we had a new typesetter and troff had just been invented and we were intoxicated by being able to produce small caps". Many of the operating system's predecessors and contemporaries used all-uppercase lettering, so many people wrote the name in upper case due to force of habit. It is not an acronym. Trademark names can be registered by different entities in different countries and trademark laws in some countries allow the same trademark name to be controlled by two different entities if each entity uses the trademark in easily distinguishable categories. The result is that Unix has been used as a brand name for various products including bookshelves, ink pens, bottled glue, diapers, hair driers and food containers. Several plural forms of Unix are used casually to refer to multiple brands of Unix and Unix-like systems. Most common is the conventional Unixes, but Unices, treating Unix as a Latin noun of the third declension, is also popular. The pseudo-Anglo-Saxon plural form Unixen is not common, although occasionally seen. Sun Microsystems, developer of the Solaris variant, has asserted that the term Unix is itself plural, referencing its many implementations. See also Comparison of operating systems and free and proprietary software List of operating systems, Unix systems, and Unix commands Market share of operating systems Timeline of operating systems Plan 9 from Bell Labs Unix time Year 2038 problem References Further reading General Lions, John: Lions' with Source Code, Peer-to-Peer Communications, 1996; Books Salus, Peter H.: A Quarter Century of UNIX, Addison Wesley, June 1, 1994; Television Computer Chronicles (1985). "UNIX". Computer Chronicles (1989). "Unix". Talks External links The UNIX Standard, at The Open Group. The Unix Tree: files from historic releases Unix History Repository — a git repository representing a reconstructed version of the Unix history The Unix 1st Edition Manual 1st Edition manual rendered to HTML (film about Unix featuring Dennis Ritchie, Ken Thompson, Brian Kernighan, Alfred Aho, and more) (complementary film to the preceding "Making Computers More Productive") audio bsdtalk170 - Marshall Kirk McKusick at DCBSDCon -- on history of tcp/ip (in BSD) -- abridgement of the three lectures on the history of BSD. A History of UNIX before Berkeley: UNIX Evolution: 1975-1984 BYTE Magazine, September 1986: UNIX and the MC68000 a software perspective on the MC68000 CPU architecture and UNIX compatibility 1969 software Operating system families Time-sharing operating systems

Operating System (OS)

Chrome OS Chrome OS (sometimes styled as chromeOS) is a Gentoo Linux-based operating system designed by Google. It is derived from the free software Chromium OS and uses the Google Chrome web browser as its principal user interface. Unlike Chromium OS, Chrome OS is proprietary software. Google announced the project, based on Ubuntu, in July 2009, conceiving it as an operating system in which both applications and user data reside in the cloud: hence Chrome OS primarily runs web applications. Source code and a public demo came that November. The first Chrome OS laptop, known as a Chromebook, arrived in May 2011. Initial Chromebook shipments from Samsung and Acer occurred in July 2011. Chrome OS has an integrated media player and file manager. It supports Progressive Web Apps and Chrome Apps; these resemble native applications, as well as remote access to the desktop. As more Chrome OS machines have entered the market, the operating system is now seldom evaluated apart from the hardware that runs it. Android applications started to become available for the operating system in 2014, and in 2016, access to Android apps in Google Play's entirety was introduced on supported Chrome OS devices. Support for a Linux terminal and applications, known as Project Crostini, was released to the stable channel in 2018 with Chrome OS 69. This was made possible via a lightweight Linux kernel that runs containers inside a virtual machine. History Google announced Chrome OS on July 7, 2009, describing it as an operating system in which both applications and user data reside in the cloud. To ascertain marketing requirements, the company relied on informal metrics, including monitoring the usage patterns of some 200 Chrome OS machines used by Google employees. Developers also noted their own usage patterns. Matthew Papakipos, the former engineering director for the Chrome OS project, put three machines in his house and found himself logging in for brief sessions: to make a single search query or send a short email. The initial builds of Chrome OS were based on Ubuntu, and its developer, Canonical, was an engineering partner with Google on the project. In 2010, Chrome OS moved to Gentoo Linux as its base to simplify its build process and support a variety of platforms. Sometime in 2013, Google switched Chrome OS to its own flavour of Linux. Chrome OS was initially intended for secondary devices like netbooks, not as a user's primary PC. While Chrome OS supports hard disk drives, Google has requested that its hardware partners use solid-state drives "for performance and reliability reasons" as well as the lower capacity requirements inherent in an operating system that accesses applications and most user data on remote servers. In November 2009 Matthew Papakipos, engineering director for the Chrome OS, claimed that the Chrome OS consumes one-sixtieth as much drive space as Windows 7. The recovery images Google provides for Chrome OS range between 1 and 3 GB. On November 19, 2009, Google released Chrome OS's source code as the Chromium OS project. At a November 19, 2009, news conference, Sundar Pichai, at the time Google's vice president overseeing Chrome, demonstrated an early version of the operating system. He previewed a desktop which looked very similar to the Chrome browser, and in addition to the regular browser tabs, also had application tabs, which take less space and can be pinned for easier access. At the conference, the operating system booted up in seven seconds, a time Google said it would work to reduce. Additionally, Chris Kenyon, vice president of OEM services at Canonical Ltd, announced that Canonical was under contract to contribute engineering resources to the project with the intent to build on existing open-source components and tools where feasible. Early Chromebooks In 2010, Google released the unbranded Cr-48 Chromebook in a pilot program. The launch date for retail hardware featuring Chrome OS was delayed from late 2010 until the next year. On May 11, 2011, Google announced two Chromebooks from Acer and Samsung at Google I/O. The Samsung model was released on June 15, 2011, but the Acer was delayed until mid-July. In August 2011, Netflix announced official support for Chrome OS through its streaming service, allowing Chromebooks to watch streaming movies and TV shows via Netflix. At the time, other devices had to use Microsoft Silverlight to play videos from Netflix. Later in that same month, Citrix released a client application for Chrome OS, allowing Chromebooks to access Windows applications and desktops remotely. Dublin City University became the first educational institution in Europe to provide Chromebooks for its students when it announced an agreement with Google in September 2011. Expansion By 2012, demand for Chromebooks had begun to grow, and Google announced a new range of devices, designed and manufactured by Samsung. In so doing, they also released the first Chromebox, the Samsung Series 3, which was Chrome OS's entrance into the world of desktop computers. Although they were faster than the previous range of devices, they were still underpowered compared to other desktops and laptops of the time, fitting in more closely with the Netbook market. Only months later, in October, Samsung and Google released a new Chromebook at a significantly lower price point ($250, compared to the previous Series 5 Chromebooks' $450). It was the first Chromebook to use an ARM processor, one from Samsung's Exynos line. To reduce the price, Google and Samsung also reduced the memory and screen resolution of the device. An advantage of using the ARM processor, however, was that the Chromebook didn't require a fan. Acer followed quickly after with the C7 Chromebook, priced even lower ($199), but containing an Intel Celeron processor. One notable way Acer reduced the cost of the C7 was to use a laptop hard disk rather than a solid-state drive. In April 2012, Google made the first update to Chrome OS's user interface since the operating system had launched, introducing a hardware-accelerated window manager called "Aura" along with a conventional taskbar. The additions marked a departure from the operating system's original concept of a single browser with tabs and gave Chrome OS the look and feel of a more conventional desktop operating system. "In a way, this almost feels as if Google is admitting defeat here", wrote Frederic Lardinois on TechCrunch. He argued that Google had traded its original version of simplicity for greater functionality. "That's not necessarily a bad thing, though, and may just help Chrome OS gain more mainstream acceptance as new users will surely find it to be a more familiar experience." Lenovo and HP followed Samsung and Acer in manufacturing Chromebooks in early 2013 with their own models. Lenovo specifically targeted their Chromebook at students, headlining their press release with "Lenovo Introduces Rugged ThinkPad Chromebook for Schools". When Google released Google Drive, they also included Drive integration in Chrome OS version 20, released in July 2012. While Chrome OS had supported Flash since 2010, by the end of 2012 it had been fully sandboxed, preventing issues with Flash from affecting other parts of Chrome OS. This affected all versions of Chrome including Chrome OS. Chromebook Pixel Up to this point, Google had never made their own Chrome OS device. Instead, Chrome OS devices were much more similar to their Nexus line of Android phones, with each Chrome OS device being designed, manufactured, and marketed by third-party manufacturers, but with Google controlling the software. However, in February 2013 this changed when Google released the Chromebook Pixel. The Chromebook Pixel was a departure from previous devices. Not only was it entirely Google-branded, but it contained an Intel i5 processor, a high-resolution (2,560 × 1,700) touchscreen display, and came at a price more competitive with business laptops. Controversial popularity By the end of 2013, analysts were undecided on the future of Chrome OS. Although there had been articles predicting the demise of Chrome OS since 2009, Chrome OS device sales continued to increase substantially year-over-year. In mid-2014, Time magazine published an article titled "Depending on Who's Counting, Chromebooks are Either an Enormous Hit or Totally Irrelevant", which detailed the differences in opinion. This controversy was further spurred by the fact that Intel seemed to decide Chrome OS was a beneficial market for it, holding their own Chrome OS events where they announced new Intel-based Chromebooks, Chromeboxes, and an all-in-one from LG called the Chromebase. Seizing the opportunity created by the end of life for Windows XP, Google pushed hard to sell Chromebooks to businesses, offering significant discounts in early 2014. Chrome OS devices outsold Apple Macs worldwide for the year 2020. Pwnium competition In March 2014, Google hosted a hacking contest aimed at computer security experts called "Pwnium". Similar to the Pwn2Own contest, they invited hackers from around the world to find exploits in Chrome OS, with prizes available for attacks. Two exploits were demonstrated there, and a third was demonstrated at that year's Pwn2Own competition. Google patched the issues within a week. Material Design and app runtime for Chrome Although the Google Native Client has been available on Chrome OS since 2010, there originally were few Native Client apps available, and most Chrome OS apps were still web apps. However, in June 2014, Google announced at Google I/O that Chrome OS would both synchronise with Android phones to share notifications and begin to run Android apps, installed directly from Google Play. This, along with the broadening selection of Chromebooks, provided an interesting future for Chrome OS. At the same time, Google was also moving towards the then-new Material Design design language for its products, which it would bring to its web products as well as Android Lollipop. One of the first Material Design items to come to Chrome OS was a new default wallpaper, though Google did release some screenshots of a Material Design experiment for Chrome OS that never made it into the stable version. Functionality for small and medium businesses and Enterprise Chrome Enterprise Chrome Enterprise, launched in 2017, includes Chrome OS, Chrome Browser, Chrome devices and their management capabilities intended for business use. Businesses can access the standard Chrome OS features and unlock advanced features for business with the Chrome Enterprise Upgrade. Standard features include the ability to sync bookmarks and browser extensions across devices, cloud or native printing, multi-layered security, remote desktop, and automatic updates. Advanced features include Active Directory integration, unified endpoint management, advanced security protection, access to device policies and Google Admin console, guest access, kiosk mode, and whitelisting or blacklisting third-party apps managed on Google Play. The education sector was an early adopter of Chromebooks, Chrome OS, and cloud-based computing. Chromebooks are widely used in classrooms and the advantages of cloud-based systems have been gaining an increased share of the market in other sectors as well, including financial services, healthcare, and retail. "The popularity of cloud computing and cloud-based services highlights the degree to which companies and business processes have become both internet-enabled and dependent." IT managers cite a number of advantages of the cloud that have motivated the move. Among them are advanced security, because data is not physically on a single machine that can be lost or stolen. Deploying and managing cloud-native devices is easier because no hardware and software upgrades or virus definition updates are needed and patching of OS and software updates are simpler. Simplified and centralized management decreases operational costs. Employees can securely access files and work on any machine, increasing the shareability of Chrome devices. Google's Grab and Go program with Chrome Enterprise allows businesses deploying Chromebooks to provide employees access to a bank of fully charged computers that can be checked out and returned after some time. From Chromebooks to Chromebox and Chromebase In an early attempt to expand its enterprise offerings, Google released Chromebox for Meetings in February 2014. Chromebox for Meetings is a kit for conference rooms containing a Chromebox, a camera, a unit containing both a noise-cancelling microphone and speakers, and a remote control. It supports Google Hangouts meetings, Vidyo video conferences, and conference calls from UberConference. Several partners announced Chromebox for Meetings models with Google, and in 2016 Google announced an all-in-one Chromebase for Meetings for smaller meeting rooms. Google targeted the consumer hardware market with the release of the Chromebook in 2011 and Chromebook Pixel in 2013, and sought access to the enterprise market with the 2017 release of the Pixelbook. The second-generation Pixelbook was released in 2019. In 2021 there are several vendors selling all-in-one Chromebase devices. Enterprise response to Chrome devices Google has partnered on Chrome devices with several leading OEMs, including Acer, ASUS, Dell, HP, Lenovo, and Samsung. In August 2019, Dell announced that two of its popular business-focused laptops would run Chrome OS and come with Chrome Enterprise Upgrade. The Latitude 5300 2-in-1 Chromebook Enterprise and Latitude 5400 Chromebook Enterprise were the result of a two-year partnership between Dell and Google. The machines come with a bundle of Dell's cloud-based support services that would enable enterprise IT managers to deploy them in environments that also rely on Windows. The new laptop line "delivers the search giant's Chrome OS operating system in a form tailored for security-conscious organizations." Other OEMs that have launched devices with Chrome Enterprise Upgrade include Acer and HP. With a broader range of hardware available, Chrome OS became an option for enterprises wishing to avoid a migration to Windows 10 before Windows 7 support was discontinued by Microsoft. Hardware Laptops running Chrome OS are known collectively as "Chromebooks". The first was the CR-48, a reference hardware design that Google gave to testers and reviewers beginning in December 2010. Retail machines followed in May 2011. A year later, in May 2012, a desktop design marketed as a "Chromebox" was released by Samsung. In March 2015 a partnership with AOPEN was announced and the first commercial Chromebox was developed. In early 2014, LG Electronics introduced the first device belonging to the new all-in-one form factor called "Chromebase". Chromebase devices are essentially Chromebox hardware inside a monitor with a built-in camera, microphone and speakers. The Chromebit is an HDMI dongle running Chrome OS. When placed in an HDMI slot on a television set or computer monitor, the device turns that display into a personal computer. The first device, announced in March 2015 was an Asus unit that shipped that November and which reached end of life in November 2020. Chromebook tablets were introduced in March 2018 by Acer with their Chromebook Tab 10. Designed to rival the Apple iPad, it had an identical screen size and resolution and other similar specifications, a notable addition was a Wacom-branded stylus that doesn’t require a battery or charging. Chrome OS supports multi-monitor setups, on devices with a video-out port, USB 3.0 or USB-C, the latter being preferable. On February 16, 2022, Google announced a development version of Chrome OS Flex—a distribution of Chrome OS that can be installed on conventional PC hardware to replace other operating systems such as Windows. It is similar to CloudReady, a distribution of Chromium OS whose developers were acquired by Google in 2020. Software The software and updates are limited in their support lifetime. Each device model manufactured to run Chrome OS has a different end-of-life date, with all new devices released in 2020 and beyond guaranteed to receive a minimum of eight years from their date of initial release. As of Version 78, the device's end-of-life date for software updates is listed in "About Chrome OS"-"Additional Details". Applications Initially, Chrome OS was almost a pure web thin client operating system that relied primarily on servers to host web applications and related data storage. Google gradually began encouraging developers to create "packaged applications", and later, Chrome Apps. The latter employ HTML5, CSS, Adobe Shockwave, and JavaScript to provide a user experience closer to a native application. In September 2014, Google launched App Runtime for Chrome (beta), which allowed certain ported Android applications to run on Chrome OS. Runtime was launched with four Android applications: Duolingo, Evernote, Sight Words, and Vine. In 2016, Google made Google Play available for Chrome OS, making most Android apps available for supported Chrome OS devices. In 2018, Google announced plans for Chrome OS support for desktop Linux apps. This capability was released to the stable channel (as an option for most machines) with Chrome 69 in October 2018, but was still marked as beta. This feature was officially released with Chrome 91. By default X11 is not used, while X11 apps can be run. Project Crostini makes X11 work (through Wayland). Chrome Apps From 2013 until January 2020, Google encouraged developers to build not just conventional Web applications for Chrome OS, but Chrome Apps (formerly known as Packaged Apps). In January 2020, Google's Chrome team announced its intent to phase out support for Chrome Apps in favor of "progressive web applications" (PWA) and Chrome extensions instead. In March 2020, Google stopped accepting new public Chrome Apps for the web store. According to Google, general support for Chrome Apps on Chrome OS will remain enabled, without requiring any policy setting, through June 2022. From a user's perspective, Chrome Apps resemble conventional native applications: they can be launched outside of the Chrome browser, are offline by default, can manage multiple windows, and interact with other applications. Technologies employed include HTML5, JavaScript, and CSS. Integrated media player, file manager Google integrates a media player into both Chrome OS and the Chrome browser, enabling users to play back MP3s, view JPEGs, and handle other multimedia files while offline. It also supports DRM videos. Chrome OS also includes an integrated file manager, resembling those found on other operating systems, with the ability to display directories and the files they contain from both Google Drive and local storage, as well as to preview and manage file contents using a variety of Web applications, including Google Docs and Box. Since January 2015, Chrome OS can also integrate additional storage sources into the file manager, relying on installed extensions that use the File System Provider API. Remote application access and virtual desktop access In June 2010, Google software engineer Gary Kačmarčík wrote that Chrome OS would access remote applications through a technology unofficially called "Chromoting", which would resemble Microsoft's Remote Desktop Connection. The name has since been changed to "Chrome Remote Desktop", and is like "running an application via Remote Desktop Services or by first connecting to a host machine by using RDP or VNC". Initial roll-outs of Chrome OS laptops (Chromebooks) indicate an interest in enabling users to access virtual desktops. Android applications At Google I/O 2014, a proof of concept showing Android applications, including Flipboard, running on Chrome OS was presented. In September 2014, Google introduced a beta version of the App Runtime for Chrome (ARC), which allows selected Android applications to be used on Chrome OS, using a Native Client-based environment that provides the platforms necessary to run Android software. Android applications do not require any modifications to run on Chrome OS, but may be modified to better support a mouse and keyboard environment. At its introduction, Chrome OS support was only available for selected Android applications. In 2016, Google introduced the ability to run Android apps on supported Chrome OS devices, with access to Google Play in its entirety. The previous Native Client-based solution was dropped in favor of a container containing Android's frameworks and dependencies (initially based on Android Marshmallow), which allows Android apps to have direct access to the Chrome OS platform, and allow the OS to interact with Android contracts such as sharing. Engineering director Zelidrag Hornung explained that ARC had been scrapped due to its limitations, including its incompatibility with the Android Native Development Toolkit (NDK), and that it was unable to pass Google's own compatibility test suite. Linux apps All Chromebooks made since 2018, and many earlier models, can run Linux apps. As with Android apps, these apps can be installed and launched alongside other apps. Google maintains a list of devices that were launched before 2019, which support Linux apps. Since 2013, it has been possible to run Linux applications in Chrome OS through the use of Crouton, a third-party set of scripts that allows access to a Linux distribution such as Ubuntu. However, in 2018 Google announced that desktop Linux apps were officially coming to Chrome OS. The main benefit claimed by Google of their official Linux application support is that it can run without enabling developer mode, keeping many of the security features of Chrome OS. It was noticed in the Chromium OS source code in early 2018. Early parts of Crostini were made available for the Google Pixelbook via the dev channel in February 2018 as part of Chrome OS version 66, and it was enabled by default via the beta channel for testing on a variety of Chromebooks in August 2018 with version 69. Architecture Google's project for supporting Linux applications in Chrome OS is called Crostini, named for the Italian bread-based starter, and as a pun on Crouton. Crostini runs a virtual machine through a virtual machine monitor called crosvm, which uses Linux's built-in KVM virtualization tool. Although crosvm supports multiple virtual machines, the one used for running Linux apps, Termina, contains a basic Chrome OS kernel and userland utilities, in which it runs containers based on Linux containers (specifically LXD). Architecture Chrome OS is built on top of the Linux kernel. Originally based on Ubuntu, its base was changed to Gentoo Linux in February 2010. For Project Crostini, as of Chrome OS 80, Debian 10 (Buster) is used. In preliminary design documents for the Chromium OS open-source project, Google described a three-tier architecture: firmware, browser and window manager, and system-level software and userland services. The firmware contributes to fast boot time by not probing for hardware, such as floppy disk drives, that are no longer common on computers, especially netbooks. The firmware also contributes to security by verifying each step in the boot process and incorporating system recovery. System-level software includes the Linux kernel that has been patched to improve boot performance. Userland software has been trimmed to essentials, with management by Upstart, which can launch services in parallel, re-spawn crashed jobs, and defer services in the interest of faster booting. The window manager handles user interaction with multiple client windows (much like other X window managers). Security In March 2010, Google software security engineer Will Drewry discussed Chrome OS security. Drewry described Chrome OS as a "hardened" operating system featuring auto-updating and sandbox features that would reduce malware exposure. He said that Chrome OS netbooks would be shipped with Trusted Platform Module (TPM), and include both a "trusted boot path" and a physical switch under the battery compartment that activates a "developer mode". That mode drops some specialized security functions but increases developer flexibility. Drewry also emphasized that the open-source nature of the operating system would contribute greatly to its security by allowing constant developer feedback. At a December 2010 press conference, Google declared that Chrome OS would be the most secure consumer operating system due in part to a verified boot ability, in which the initial boot code, stored in read-only memory, checks for system compromises. In the following nine years, Chrome OS has been affected by 55 documented security flaws of any severity, compared with over 1,100 affecting Microsoft Windows 10 in the five years to the end of 2019 and over 2,200 affecting Apple OS X in 20 years. Shell access Chrome OS includes the Chrome Shell, or "crosh", which documents minimal functionality such as ping at crosh start-up. In developer mode, a full-featured bash shell (which is supposed to be used for development purposes) can be opened via VT-2, and is also accessible using the crosh command shell. To access full privileges in shell (e.g. sudo) a root password is requested. For some time the default was "chronos" in Chrome OS and "facepunch" in Chrome OS Vanilla and later the default was empty, and instructions on updating it were displayed at each login. Open source Chrome OS is partially developed under the open-source Chromium OS project. As with other open-source projects, developers can modify the code from Chromium OS and build their own versions, whereas Chrome OS code is only supported by Google and its partners and only runs on hardware designed for the purpose. Unlike Chromium OS, Chrome OS is automatically updated to the latest version. Chrome OS on Windows On Windows 8, exceptions allow the default desktop web browser to offer a variant that can run inside its full-screen "Metro" shell and access features such as the Share charm, without necessarily needing to be written with Windows Runtime. Chrome's "Windows 8 mode" was previously a tablet-optimized version of the standard Chrome interface. In October 2013, the mode was changed on Developer channel to offer a variant of the Chrome OS desktop. Design Early in the project, Google provided publicly many details of Chrome OS's design goals and direction, although the company has not followed up with a technical description of the completed operating system. User interface Design goals for Chrome OS's user interface included using minimal screen space by combining applications and standard Web pages into a single tab strip, rather than separating the two. Designers considered a reduced window management scheme that would operate only in full-screen mode. Secondary tasks would be handled with "panels": floating windows that dock to the bottom of the screen for tasks like chat and music players. Split screens were also under consideration for viewing two pieces of content side by side. Chrome OS would follow the Chrome browser's practice of leveraging HTML5's offline modes, background processing, and notifications. Designers proposed using search and pinned tabs as a way to quickly locate and access applications. Version 19 window manager and graphics engine On April 10, 2012, a new build of Chrome OS offered a choice between the original full-screen window interface and overlapping, re-sizable windows, such as found on Microsoft Windows and Apple's macOS. The feature was implemented through the Ash window manager, which runs atop the Aura hardware-accelerated graphics engine. The April 2012 upgrade also included the ability to display smaller, overlapping browser windows, each with its own translucent tabs, browser tabs that can be "torn" and dragged to new positions or merged with another tab strip, and a mouse-enabled shortcut list across the bottom of the screen. One icon on the task bar shows a list of installed applications and bookmarks. Writing in CNET, Stephen Shankland argued that with overlapping windows, "Google is anchoring itself into the past" as both iOS and Microsoft's Metro interface are largely or entirely full-screen. Even so, "Chrome OS already is different enough that it's best to preserve any familiarity that can be preserved". Printing Google Cloud Print is a Google service that helps any application on any device to print on supported printers. While the cloud provides virtually any connected device with information access, the task of "developing and maintaining print subsystems for every combination of hardware and operating system—from desktops to netbooks to mobile devices—simply isn't feasible." The cloud service requires installation of a piece of software called proxy, as part of the Chrome OS. The proxy registers the printer with the service, manages the print jobs, provides the printer driver functionality, and gives status alerts for each job. In 2016, Google included "Native CUPS Support" in Chrome OS as an experimental feature that may eventually become an official feature. With CUPS support turned on, it becomes possible to use most USB printers even if they do not support Google Cloud Print. Google announced that Google Cloud Print would no longer be supported after December 31, 2020, and that the online service would not be available as of January 1, 2021. Link handling Chrome OS was designed to store user documents and files on remote servers. Both Chrome OS and the Chrome browser may introduce difficulties to end-users when handling specific file types offline; for example, when opening an image or document residing on a local storage device, it may be unclear whether and which specific Web application should be automatically opened for viewing, or the handling should be performed by a traditional application acting as a preview utility. Matthew Papakipos, Chrome OS engineering director, noted in 2010 that Windows developers have faced the same fundamental problem: "Quicktime is fighting with Windows Media Player, which is fighting with Chrome." Release channels and updates Chrome OS uses the same release system as Google Chrome: there are three distinct channels: Stable, Beta, and Developer preview (called the "Dev" channel). The stable channel is updated with features and fixes that have been thoroughly tested in the Beta channel, and the Beta channel is updated approximately once a month with stable and complete features from the Developer channel. New ideas get tested in the Developer channel, which can be very unstable at times. A fourth canary channel was confirmed to exist by Google Developer Francois Beaufort and hacker Kenny Strawn, by entering the Chrome OS shell in developer mode, typing the command to access the bash shell, and finally entering the command . It is possible to return to the verified boot mode after entering the canary channel, but the channel updater disappears and the only way to return to another channel is using the "powerwash" factory reset. Reception At its debut, Chrome OS was viewed as a competitor to Microsoft, both directly to Microsoft Windows and indirectly the company's word processing and spreadsheet applications—the latter through Chrome OS's reliance on cloud computing. But Chrome OS engineering director Matthew Papakipos argued that the two operating systems would not fully overlap in functionality because Chrome OS is intended for netbooks, which lack the computational power to run a resource-intensive program like Adobe Photoshop. Some observers claimed that other operating systems already filled the niche that Chrome OS was aiming for, with the added advantage of supporting native applications in addition to a browser. Tony Bradley of PC World wrote in November 2009: In 2016, Chromebooks were the most popular computer in the US K–12 education market. By 2017, the Chrome browser had risen to become the number one browser used worldwide. In 2020, Chromebooks became the second most-popular end-user oriented OS (growing from 6.4% in 2019 to 10.8% in 2020). The majority of growth came at Windows expense (which fell from 85.4% in 2019 to 80.5% in 2021). Relationship to Android Google's offering of two open-source operating systems, Android and Chrome OS, has drawn some criticism despite the similarity between this situation and that of Apple Inc.'s two operating systems, macOS and iOS. Steve Ballmer, Microsoft CEO at the time, accused Google of not being able to make up its mind. Steven Levy wrote that "the dissonance between the two systems was apparent" at Google I/O 2011. The event featured a daily press conference in which each team leader, Android's Andy Rubin and Chrome's Sundar Pichai, "unconvincingly tried to explain why the systems weren't competitive". Google co-founder Sergey Brin addressed the question by saying that owning two promising operating systems was "a problem that most companies would love to face". Brin suggested that the two operating systems "will likely converge over time". The speculation over convergence increased in March 2013 when Chrome OS chief Pichai replaced Rubin as the senior vice president in charge of Android, thereby putting Pichai in charge of both. The relationship between Android and Chrome OS became more substantial at Google I/O 2014, where developers demonstrated native Android software running on Chrome OS through a Native Client-based runtime. In September 2014, Google introduced a beta version of the App Runtime for Chrome (ARC), which allows selected Android applications to be used on Chrome OS, using a Native Client-based environment that provides the platforms necessary to run Android software. Android applications do not require any modifications to run on Chrome OS, but may be modified to better support a mouse and keyboard environment. At its introduction, Chrome OS support was only available for selected Android applications. In October 2015, The Wall Street Journal reported that Chrome OS would be folded into Android so that a single OS would result by 2017. The resulting OS would be Android, but it would be expanded to run on laptops. Google responded that while the company has "been working on ways to bring together the best of both operating systems, there's no plan to phase out Chrome OS". In 2016, Google introduced the ability to run Android apps on supported Chrome OS devices, with access to Google Play in its entirety. The previous Native Client-based solution was dropped in favor of a container containing Android's frameworks and dependencies (initially based on Android Marshmallow), which allows Android apps to have direct access to the Chrome OS platform, and allow the OS to interact with Android contracts such as sharing. Engineering director Zelidrag Hornung explained that ARC had been scrapped due to its limitations, including its incompatibility with the Android Native Development Toolkit (NDK), and that it was unable to pass Google's own compatibility test suite. See also Comparison of operating systems Google Fuchsia List of operating systems for information on typing diacritics (accents) and special symbols Timeline of operating systems Notes References External links Official website Official blog Release blog Chromium OS project page Official announcement Google Chrome OS Live Webcast; November 19, 2009 2011 software ARM operating systems Computer-related introductions in 2011 Google operating systems Google Mobile operating systems Tablet operating systems Operating systems based on the Linux kernel Linux distributions without systemd X86 operating systems Proprietary operating systems Linux distributions Gentoo Linux derivatives

Operating System (OS)

SOX (operating system) SOX is a discontinued UNIX clone. It was developed from scratch in Brazil, in the late 1980s, by Computadores e Sistemas Brasileiros S/A (now Cobra Tecnologia), under the leadership of Ivan da Costa Marques. Certified as UNIX-compatible by X/Open (through UniSoft) in early 1989, SOX was one of the first re-implementations of UNIX, fully independent of AT&T, that passed the X/Open verification tests, and the only one ever completed entirely outside the United States. SOX was designed to run on COBRA's own minicomputers and was the result of the Brazilian Informatics Policy, which aimed to achieve technological independence from the United States. Despite being a technical success, SOX came too late, when COBRA had largely lost its support. SOX development stopped soon after it was certified, when the government decided to allow use of UNIX System V Release 4.0. See also COSIX History of Unix References Peter Evans (1995) Embedded Autonomy: States and Industrial Transformation, Princeton, NJ: Princeton University Press Gustavo Gindre Monteiro Soares (2002) "A Politica dos Artifatos na Lei de Informática: o Caso SOX", XXV Congresso Brasileiro de Ciência de Comunicação, Salvador, Bahia. Luis Ferreira (aka Luix). Proposta de uma Arquitetura para um Sistema Operacional de Tempo Real. 1985. Dissertação (Mestrado em Engenharia de Sistemas e Computação) - Universidade Federal do Rio de Janeiro, Orientadores: Sueli Bandeira Teixeira Mendes and Firmo Freire. Márcia de Oliveira Cardoso. SOX: Um UNIX-compatível brasileiro a serviço do discurso de autonomia tecnológica. 2013. Tese de Doutorado apresentada ao Programa de Pós-Graduação História das Ciências e das Técnicas e Epistemologia, Universidade Federal do Rio de Janeiro, Orientador: José Carlos de Oliveira. http://sox-4s.pbworks.com/w/page/7219509/FrontPage Information technology in Brazil Unix variants

Operating System (OS)

Galileo (operating system) Galileo was an unreleased 32-bit operating system that was under development by Acorn Computers as a long-term project to produce "an ultra-modern scalable, portable, multi-tasking, multi-threading, object-oriented, microkernel operating system", reportedly significant enough to Acorn's strategy to warrant a statement to the financial markets. Announced in early 1997 as targeting "the next generation of smart appliances", running initially on ARM architecture devices but intended to be easily portable to "other RISC processors" (or even "a range of RISC and CISC processors"), emphasis was made on its quality of service features that would guarantee system resources to critical tasks, as well as its reliability, its sophistication relative to RISC OS (which was described as "too primitive to succeed as a 21st century operating system"), and its small footprint that would "enable Acorn to compete in the semi-embedded systems market". However, the system's "modular object-oriented" architecture gave it the scalability to potentially be deployed in devices ranging from "multimedia cellular phones" and network computers to desktop workstations and server platforms. Features The operating system was to offer an "innovative modular real time kernel", also described as a microkernel with a hardware abstraction layer, having a footprint of only 15 KB. The kernel itself supported preemptive multitasking, being "multi-threaded and fully pre-emptive", and was portable through extensive high-level language use (an estimated 95% of the code) in conjunction with the hardware abstraction layer. Kernel responsibilities included memory allocation, interrupt handling, direct memory access services, scheduling, and the resource allocation required by the quality of service functionality. Systems using Galileo were to be able to leverage the modularity of the software architecture to deliver a "complete customisable software stack" that could be deployed in ROM, with system modules and applications being executed in-place to reduce RAM requirements. The architecture was also meant to allow additional components, such as multimedia codecs or network stacks, to be downloaded and deployed without the need to restart the system. It was noted that "virtually all Galileo tasks run in user mode", with "complete memory and CPU usage protection" enforced to uphold the quality of service regime. The inclusion of quality of service features was intended to "eliminate the need for dedicated multimedia chips" in consumer-level Internet appliances, particularly those chips concerned with video compression and decompression that might instead be implemented in software, thus helping manufacturers to reduce system costs below an anticipated target given of $100 by 1998. Such objectives were to be achieved through collaboration with system-on-chip manufacturers, with a specific collaboration in progress mentioned in early 1997, and with "companies such as Hitachi" expected to release suitable hardware in 1998. Fate The operating system was scheduled to be the successor of RISC OS, although Acorn envisaged RISC OS remaining relevant for "high functionality ARM based devices" in the short to medium term, with Galileo being aimed at "portable and networked interactive media devices". Early versions for existing Acorn customers were anticipated by the second half of 1997, and the Galileo kernel was stated as having been "up and running" as a prototype, but the project was cancelled when the workstation division closed as part of Acorn's restructuring in 1998. The commercial potential of Galileo had been put into some doubt by the announcement of the Symbian alliance which established Psion's EPOC operating system as the basis of a mobile communications platform to be adopted by Nokia and Ericsson, with Motorola having also announced a commitment to the initiative. Despite Galileo promising to be "technically better" than EPOC, the comparative readiness of the two offerings was summarised in one publication's remark that "EPOC has started the race while Galileo is still in the pits with its engine in bits". Nevertheless, at that time, hopes were expressed for opportunities for the product in set-top boxes and network computers. References Acorn operating systems ARM operating systems

Operating System (OS)

Architecture of Windows NT The architecture of Windows NT, a line of operating systems produced and sold by Microsoft, is a layered design that consists of two main components, user mode and kernel mode. It is a preemptive, reentrant multitasking operating system, which has been designed to work with uniprocessor and symmetrical multiprocessor (SMP)-based computers. To process input/output (I/O) requests, they use packet-driven I/O, which utilizes I/O request packets (IRPs) and asynchronous I/O. Starting with Windows XP, Microsoft began making 64-bit versions of Windows available; before this, there were only 32-bit versions of these operating systems. Programs and subsystems in user mode are limited in terms of what system resources they have access to, while the kernel mode has unrestricted access to the system memory and external devices. Kernel mode in Windows NT has full access to the hardware and system resources of the computer. The Windows NT kernel is a hybrid kernel; the architecture comprises a simple kernel, hardware abstraction layer (HAL), drivers, and a range of services (collectively named Executive), which all exist in kernel mode. User mode in Windows NT is made of subsystems capable of passing I/O requests to the appropriate kernel mode device drivers by using the I/O manager. The user mode layer of Windows NT is made up of the "Environment subsystems", which run applications written for many different types of operating systems, and the "Integral subsystem", which operates system-specific functions on behalf of environment subsystems. The kernel mode stops user mode services and applications from accessing critical areas of the operating system that they should not have access to. The Executive interfaces, with all the user mode subsystems, deal with I/O, object management, security and process management. The kernel sits between the hardware abstraction layer and the Executive to provide multiprocessor synchronization, thread and interrupt scheduling and dispatching, and trap handling and exception dispatching. The kernel is also responsible for initializing device drivers at bootup. Kernel mode drivers exist in three levels: highest level drivers, intermediate drivers and low-level drivers. Windows Driver Model (WDM) exists in the intermediate layer and was mainly designed to be binary and source compatible between Windows 98 and Windows 2000. The lowest level drivers are either legacy Windows NT device drivers that control a device directly or can be a plug and play (PnP) hardware bus. User mode User mode is made up of various system-defined processes and DLLs. The interface between user mode applications and operating system kernel functions is called an "environment subsystem." Windows NT can have more than one of these, each implementing a different API set. This mechanism was designed to support applications written for many different types of operating systems. None of the environment subsystems can directly access hardware; access to hardware functions is done by calling into kernel mode routines. There are three main environment subsystems: the Win32 subsystem, an OS/2 subsystem and a POSIX subsystem. Win32 environment subsystem The Win32 environment subsystem can run 32-bit Windows applications. It contains the console as well as text window support, shutdown and hard-error handling for all other environment subsystems. It also supports Virtual DOS Machines (VDMs), which allow MS-DOS and 16-bit Windows (Win16) applications to run on Windows NT. There is a specific MS-DOS VDM that runs in its own address space and which emulates an Intel 80486 running MS-DOS 5.0. Win16 programs, however, run in a Win16 VDM. Each program, by default, runs in the same process, thus using the same address space, and the Win16 VDM gives each program its own thread on which to run. However, Windows NT does allow users to run a Win16 program in a separate Win16 VDM, which allows the program to be preemptively multitasked, as Windows NT will pre-empt the whole VDM process, which only contains one running application. The Win32 environment subsystem process (csrss.exe) also includes the window management functionality, sometimes called a "window manager". It handles input events (such as from the keyboard and mouse), then passes messages to the applications that need to receive this input. Each application is responsible for drawing or refreshing its own windows and menus, in response to these messages. OS/2 environment subsystem The OS/2 environment subsystem supports 16-bit character-based OS/2 applications and emulates OS/2 1.x, but not 32-bit or graphical OS/2 applications as used with OS/2 2.x or later, on x86 machines only. To run graphical OS/2 1.x programs, the Windows NT Add-On Subsystem for Presentation Manager must be installed. The last version of Windows NT to have an OS/2 subsystem was Windows 2000; it was removed as of Windows XP. POSIX environment subsystem The POSIX environment subsystem supports applications that are strictly written to either the POSIX.1 standard or the related ISO/IEC standards. This subsystem has been replaced by Interix, which is a part of Windows Services for UNIX. This was in turn replaced by the Windows Subsystem for Linux. Security subsystem The security subsystem deals with security tokens, grants or denies access to user accounts based on resource permissions, handles login requests and initiates login authentication, and determines which system resources need to be audited by Windows NT. It also looks after Active Directory. The workstation service implements the network redirector, which is the client side of Windows file and print sharing; it implements local requests to remote files and printers by "redirecting" them to the appropriate servers on the network. Conversely, the server service allows other computers on the network to access file shares and shared printers offered by the local system. Kernel mode Windows NT kernel mode has full access to the hardware and system resources of the computer and runs code in a protected memory area. It controls access to scheduling, thread prioritization, memory management and the interaction with hardware. The kernel mode stops user mode services and applications from accessing critical areas of the operating system that they should not have access to; user mode processes must ask the kernel mode to perform such operations on their behalf. While the x86 architecture supports four different privilege levels (numbered 0 to 3), only the two extreme privilege levels are used. Usermode programs are run with CPL 3, and the kernel runs with CPL 0. These two levels are often referred to as "ring 3" and "ring 0", respectively. Such a design decision had been done to achieve code portability to RISC platforms that only support two privilege levels, though this breaks compatibility with OS/2 applications that contain I/O privilege segments that attempt to directly access hardware. Code running in kernel mode includes: the executive, which is itself made up of many modules that do specific tasks; the kernel, which provides low-level services used by the Executive; the Hardware Abstraction Layer (HAL); and kernel drivers. Executive The Windows Executive services make up the low-level kernel-mode portion, and are contained in the file NTOSKRNL.EXE. It deals with I/O, object management, security and process management. These are divided into several subsystems, among which are Cache Manager, Configuration Manager, I/O Manager, Local Procedure Call (LPC), Memory Manager, Object Manager, Process Structure and Security Reference Monitor (SRM). Grouped together, the components can be called Executive services (internal name Ex). System Services (internal name Nt), i.e., system calls, are implemented at this level, too, except very few that call directly into the kernel layer for better performance. The term "service" in this context generally refers to a callable routine, or set of callable routines. This is distinct from the concept of a "service process", which is a user mode component somewhat analogous to a daemon in Unix-like operating systems. Object Manager The Object Manager (internal name Ob) is an executive subsystem that all other executive subsystems, especially system calls, must pass through to gain access to Windows NT resources—essentially making it a resource management infrastructure service. The object manager is used to reduce the duplication of object resource management functionality in other executive subsystems, which could potentially lead to bugs and make development of Windows NT harder. To the object manager, each resource is an object, whether that resource is a physical resource (such as a file system or peripheral) or a logical resource (such as a file). Each object has a structure or object type that the object manager must know about. Object creation is a process in two phases, creation and insertion. Creation causes the allocation of an empty object and the reservation of any resources required by the object manager, such as an (optional) name in the namespace. If creation was successful, the subsystem responsible for the creation fills in the empty object. Finally, if the subsystem deems the initialization successful, it instructs the object manager to insert the object, which makes it accessible through its (optional) name or a cookie called a handle. From then on, the lifetime of the object is handled by the object manager, and it's up to the subsystem to keep the object in a working condition until being signaled by the object manager to dispose of it. Handles are identifiers that represent a reference to a kernel resource through an opaque value. Similarly, opening an object through its name is subject to security checks, but acting through an existing, open handle is only limited to the level of access requested when the object was opened or created. Object types define the object procedures and any data specific to the object. In this way, the object manager allows Windows NT to be an object-oriented operating system, as object types can be thought of as polymorphic classes that define objects. Most subsystems, though, with a notable exception in the I/O Manager, rely on the default implementation for all object type procedures. Each instance of an object that is created stores its name, parameters that are passed to the object creation function, security attributes and a pointer to its object type. The object also contains an object close procedure and a reference count to tell the object manager how many other objects in the system reference that object and thereby determines whether the object can be destroyed when a close request is sent to it. Every named object exists in a hierarchical object namespace. Cache Controller Closely coordinates with the Memory Manager, I/O Manager and I/O drivers to provide a common cache for regular file I/O. The Windows Cache Manager operates on file blocks (rather than device blocks), for consistent operation between local and remote files, and ensures a certain degree of coherency with memory-mapped views of files, since cache blocks are a special case of memory-mapped views and cache misses a special case of page faults. Configuration Manager Implements the system calls needed by Windows Registry. I/O Manager Allows devices to communicate with user-mode subsystems. It translates user-mode read and write commands into read or write IRPs which it passes to device drivers. It accepts file system I/O requests and translates them into device specific calls, and can incorporate low-level device drivers that directly manipulate hardware to either read input or write output. It also includes a cache manager to improve disk performance by caching read requests and write to the disk in the background. Local Procedure Call (LPC) Provides inter-process communication ports with connection semantics. LPC ports are used by user-mode subsystems to communicate with their clients, by Executive subsystems to communicate with user-mode subsystems, and as the basis for the local transport for Microsoft RPC. Memory Manager Manages virtual memory, controlling memory protection and the paging of memory in and out of physical memory to secondary storage, and implements a general-purpose allocator of physical memory. It also implements a parser of PE executables that lets an executable be mapped or unmapped in a single, atomic step. Starting from Windows NT Server 4.0, Terminal Server Edition, the memory manager implements a so-called session space, a range of kernel-mode memory that is subject to context switching just like user-mode memory. This lets multiple instances of the kernel-mode Win32 subsystem and GDI drivers run side-by-side, despite shortcomings in their initial design. Each session space is shared by several processes, collectively referred to as a "session". To ensure a degree of isolation between sessions without introducing a new object type, the association between processes and sessions is handled by the Security Reference Monitor, as an attribute of a security subject (token), and it can only be changed while holding special privileges. The relatively unsophisticated and ad hoc nature of sessions is due to the fact they weren't part of the initial design, and had to be developed, with minimal disruption to the main line, by a third party (Citrix Systems) as a prerequisite for their terminal server product for Windows NT, called WinFrame. Starting with Windows Vista, though, sessions finally became a proper aspect of the Windows architecture. No longer a memory manager construct that creeps into user mode indirectly through Win32, they were expanded into a pervasive abstraction affecting most Executive subsystems. As a matter of fact, regular use of Windows Vista always results in a multi-session environment. Process Structure Handles process and thread creation and termination, and it implements the concept of Job, a group of processes that can be terminated as a whole, or be placed under shared restrictions (such a total maximum of allocated memory, or CPU time). Job objects were introduced in Windows 2000. PnP Manager Handles plug and play and supports device detection and installation at boot time. It also has the responsibility to stop and start devices on demand—this can happen when a bus (such as USB or IEEE 1394 FireWire) gains a new device and needs to have a device driver loaded to support it. Its bulk is actually implemented in user mode, in the Plug and Play Service, which handles the often complex tasks of installing the appropriate drivers, notifying services and applications of the arrival of new devices, and displaying GUI to the user. Power Manager Deals with power events (power-off, stand-by, hibernate, etc.) and notifies affected drivers with special IRPs (Power IRPs). Security Reference Monitor (SRM) The primary authority for enforcing the security rules of the security integral subsystem. It determines whether an object or resource can be accessed, via the use of access control lists (ACLs), which are themselves made up of access control entries (ACEs). ACEs contain a Security Identifier (SID) and a list of operations that the ACE gives a select group of trustees—a user account, group account, or login session—permission (allow, deny, or audit) to that resource. GDI The Graphics Device Interface is responsible for tasks such as drawing lines and curves, rendering fonts and handling palettes. The Windows NT 3.x series of releases had placed the GDI component in the user-mode Client/Server Runtime Subsystem, but this was moved into kernel mode with Windows NT 4.0 to improve graphics performance. Kernel The kernel sits between the HAL and the Executive and provides multiprocessor synchronization, thread and interrupt scheduling and dispatching, and trap handling and exception dispatching; it is also responsible for initializing device drivers at bootup that are necessary to get the operating system up and running. That is, the kernel performs almost all the tasks of a traditional microkernel; the strict distinction between Executive and Kernel is the most prominent remnant of the original microkernel design, and historical design documentation consistently refers to the kernel component as "the microkernel". The kernel often interfaces with the process manager. The level of abstraction is such that the kernel never calls into the process manager, only the other way around (save for a handful of corner cases, still never to the point of a functional dependence). Hybrid kernel design The Windows NT design includes many of the same objectives as Mach, the archetypal microkernel system, one of the most important being its structure as a collection of modules that communicate via well-known interfaces, with a small microkernel limited to core functions such as first-level interrupt handling, thread scheduling and synchronization primitives. This allows for the possibility of using either direct procedure calls or interprocess communication (IPC) to communicate between modules, and hence for the potential location of modules in different address spaces (for example in either kernel space or server processes). Other design goals shared with Mach included support for diverse architectures, a kernel with abstractions general enough to allow multiple operating system personalities to be implemented on top of it and an object-oriented organisation. The primary operating system personality on Windows is the Windows API, which is always present. The emulation subsystem which implements the Windows personality is called the Client/Server Runtime Subsystem (csrss.exe). On versions of NT prior to 4.0, this subsystem process also contained the window manager, graphics device interface and graphics device drivers. For performance reasons, however, in version 4.0 and later, these modules (which are often implemented in user mode even on monolithic systems, especially those designed without internal graphics support) run as a kernel-mode subsystem. Applications that run on NT are written to one of the OS personalities (usually the Windows API), and not to the native NT API for which documentation is not publicly available (with the exception of routines used in device driver development). An OS personality is implemented via a set of user-mode DLLs (see Dynamic-link library), which are mapped into application processes' address spaces as required, together with an emulation subsystem server process (as described previously). Applications access system services by calling into the OS personality DLLs mapped into their address spaces, which in turn call into the NT run-time library (ntdll.dll), also mapped into the process address space. The NT run-time library services these requests by trapping into kernel mode to either call kernel-mode Executive routines or make Local Procedure Calls (LPCs) to the appropriate user-mode subsystem server processes, which in turn use the NT API to communicate with application processes, the kernel-mode subsystems and each other. Kernel-mode drivers Windows NT uses kernel-mode device drivers to enable it to interact with hardware devices. Each of the drivers has well defined system routines and internal routines that it exports to the rest of the operating system. All devices are seen by user mode code as a file object in the I/O manager, though to the I/O manager itself the devices are seen as device objects, which it defines as either file, device or driver objects. Kernel mode drivers exist in three levels: highest level drivers, intermediate drivers and low level drivers. The highest level drivers, such as file system drivers for FAT and NTFS, rely on intermediate drivers. Intermediate drivers consist of function drivers—or main driver for a device—that are optionally sandwiched between lower and higher level filter drivers. The function driver then relies on a bus driver—or a driver that services a bus controller, adapter, or bridge—which can have an optional bus filter driver that sits between itself and the function driver. Intermediate drivers rely on the lowest level drivers to function. The Windows Driver Model (WDM) exists in the intermediate layer. The lowest level drivers are either legacy Windows NT device drivers that control a device directly or can be a PnP hardware bus. These lower level drivers directly control hardware and do not rely on any other drivers. Hardware abstraction layer The Windows NT hardware abstraction layer (HAL) is a layer between the physical hardware of the computer and the rest of the operating system. It was designed to hide differences in hardware and provide a consistent platform on which the kernel is run. The HAL includes hardware-specific code that controls I/O interfaces, interrupt controllers and multiple processors. However, despite its purpose and designated place within the architecture, the HAL isn't a layer that sits entirely below the kernel, the way the kernel sits below the Executive: All known HAL implementations depend in some measure on the kernel, or even the Executive. In practice, this means that kernel and HAL variants come in matching sets that are specifically constructed to work together. In particular hardware abstraction does not involve abstracting the instruction set, which generally falls under the wider concept of portability. Abstracting the instruction set, when necessary (such as for handling the several revisions to the x86 instruction set, or emulating a missing math coprocessor), is performed by the kernel, or via hardware virtualization. See also Microsoft Windows library files MinWin Unix architecture Comparison of operating system kernels User-Mode Driver Framework Kernel-Mode Driver Framework Hybrid Kernel Further reading Martignetti, E.; What Makes It Page?: The Windows 7 (x64) Virtual Memory Manager () Russinovich, Mark E.; Solomon, David A.; Ionescu, A.; Windows Internals, Part1: Covering Windows Server 2008 R2 and Windows 7 () Russinovich, Mark E.; Solomon, David A.; Ionescu, A.; Windows Internals, Part2: Covering Windows Server 2008 R2 and Windows 7 () Notes and references Notes References External links Memory management in the Windows XP kernel Windows NT Windows NT kernel

Operating System (OS)

FreeBSD FreeBSD is a free and open-source Unix-like operating system descended from the Berkeley Software Distribution (BSD), which was based on Research Unix. The first version of FreeBSD was released in 1993. In 2005, FreeBSD was the most popular open-source BSD operating system, accounting for more than three-quarters of all installed simply, permissively licensed BSD systems. FreeBSD has similarities with Linux, with two major differences in scope and licensing: FreeBSD maintains a complete system, i.e. the project delivers a kernel, device drivers, userland utilities, and documentation, as opposed to Linux only delivering a kernel and drivers, and relying on third-parties for system software; and FreeBSD source code is generally released under a permissive BSD license, as opposed to the copyleft GPL used by Linux. The FreeBSD project includes a security team overseeing all software shipped in the base distribution. A wide range of additional third-party applications may be installed from binary packages using the pkg package management system or from source via FreeBSD Ports, or by manually compiling source code. Much of FreeBSD's codebase has become an integral part of other operating systems such as Darwin (the basis for macOS, iOS, iPadOS, watchOS, and tvOS), TrueNAS (an open-source NAS/SAN operating system), and the system software for the PlayStation 3 and PlayStation 4 game consoles. History Background In 1974, Professor Bob Fabry of the University of California, Berkeley, acquired a Unix source license from AT&T. Supported by funding from DARPA, the Computer Systems Research Group started to modify and improve AT&T Research Unix. They called this modified version "Berkeley Unix" or "Berkeley Software Distribution" (BSD), implementing features such as TCP/IP, virtual memory, and the Berkeley Fast File System. The BSD project was founded in 1976 by Bill Joy. But since BSD contained code from AT&T Unix, all recipients had to first get a license from AT&T in order to use BSD. In June 1989, "Networking Release 1" or simply Net-1 – the first public version of BSD – was released. After releasing Net-1, Keith Bostic, a developer of BSD, suggested replacing all AT&T code with freely-redistributable code under the original BSD license. Work on replacing AT&T code began and, after 18 months, much of the AT&T code was replaced. However, six files containing AT&T code remained in the kernel. The BSD developers decided to release the "Networking Release 2" (Net-2) without those six files. Net-2 was released in 1991. Birth of FreeBSD In 1992, several months after the release of Net-2, William and Lynne Jolitz wrote replacements for the six AT&T files, ported BSD to Intel 80386-based microprocessors, and called their new operating system 386BSD. They released 386BSD via an anonymous FTP server. The development flow of 386BSD was slow, and after a period of neglect, a group of 386BSD users decided to branch out on their own so that they could keep the operating system up to date. On 19 June 1993, the name FreeBSD was chosen for the project. The first version of FreeBSD was released in November 1993. In the early days of the project's inception, a company named Walnut Creek CDROM, upon the suggestion of the two FreeBSD developers, agreed to release the operating system on CD-ROM. In addition to that, the company employed Jordan Hubbard and David Greenman, ran FreeBSD on its servers, sponsored FreeBSD conferences and published FreeBSD-related books, including The Complete FreeBSD by Greg Lehey. By 1997, FreeBSD was Walnut Creek's "most successful product". The company later renamed itself to The FreeBSD Mall and later iXsystems. Today, FreeBSD is used by many IT companies such as IBM, Nokia, Juniper Networks, and NetApp to build their products. Certain parts of Apple's Mac OS X operating system are based on FreeBSD. Both the PlayStation 3 and Nintendo Switch operating system also borrow certain components from FreeBSD, while the PlayStation 4 operating system is derived from FreeBSD 9. Netflix, WhatsApp, and FlightAware are also examples of large, successful and heavily network-oriented companies which are running FreeBSD. Lawsuit 386BSD and FreeBSD were both derived from BSD releases. In January 1992, Berkeley Software Design Inc. (BSDi) started to release BSD/386, later called BSD/OS, an operating system similar to FreeBSD and based on 4.3BSD Net/2. AT&T filed a lawsuit against BSDi and alleged distribution of AT&T source code in violation of license agreements. The lawsuit was settled out of court and the exact terms were not all disclosed. The only one that became public was that BSDi would migrate their source base to the newer 4.4BSD-Lite2 sources. Although not involved in the litigation, it was suggested to FreeBSD that they should also move to 4.4BSD-Lite2. FreeBSD 2.0, which was released in November 1994, was the first version of FreeBSD without any code from AT&T. Features Use cases FreeBSD contains a significant collection of server-related software in the base system and the ports collection, allowing FreeBSD to be configured and used as a mail server, web server, firewall, FTP server, DNS server and a router, among other applications. FreeBSD can be installed on a regular desktop or a laptop. The X Window System is not installed by default, but is available in the FreeBSD ports collection. Wayland (display server protocol) is also available for FreeBSD (unofficially supported). A number of desktop environments such as GNOME, KDE, and Xfce, as well as lightweight window managers such as Openbox, Fluxbox, dwm, and bspwm, are also available to FreeBSD. As of FreeBSD 12, support for a modern graphics stack is available via drm-kmod. A large number of wireless adapters are supported. FreeBSD releases installation images for supported platforms. Since FreeBSD 13 the focus has been on x86-64 and aarch64 platforms which have Tier 1 support. x86-32 is a Tier 1 platform in FreeBSD 12 but is a Tier 2 platform in FreeBSD 13. 32 bit ARM processors using armv6 or armv7 also have Tier 2 support. 64 bit versions of PowerPC and RISC-V are also supported. Interest in the RISC-V architecture has been growing. The MIPS architecture port has been marked for deprecation and there is no image for any currently supported version. FreeBSD 12 supports SPARC but there is no image for FreeBSD 13. Networking FreeBSD's TCP/IP stack is based on the 4.2BSD implementation of TCP/IP which greatly contributed to the widespread adoption of these protocols. FreeBSD also supports IPv6, SCTP, IPSec, and wireless networking (Wi-Fi). The IPv6 and IPSec stacks were taken from the KAME project. Prior to version 11.0, FreeBSD supported IPX and AppleTalk protocols, but they are considered old and have now been dropped. As of FreeBSD 5.4, support for the Common Address Redundancy Protocol (CARP) was imported from the OpenBSD project. CARP allows multiple nodes to share a set of IP addresses, so if one of the nodes goes down, other nodes still can serve the requests. Storage FreeBSD has several unique features related to storage. Soft updates can protect the consistency of the UFS filesystem (widely used on the BSDs) in the event of a system crash. Filesystem snapshots allow an image of a UFS filesystem at an instant in time to be efficiently created. Snapshots allow reliable backup of a live filesystem. GEOM is a modular framework that provides RAID (levels 0, 1, 3 currently), full disk encryption, journaling, concatenation, caching, and access to network-backed storage. GEOM allows building of complex storage solutions combining ("chaining") these mechanisms. FreeBSD provides two frameworks for data encryption: GBDE and Geli. Both GBDE and Geli operate at the disk level. GBDE was written by Poul-Henning Kamp and is distributed under the two-clause BSD license. Geli is an alternative to GBDE that was written by Pawel Jakub Dawidek and first appeared in FreeBSD 6.0. From 7.0 onward, FreeBSD supports the ZFS filesystem. ZFS was previously an open-source filesystem that was first developed by Sun Microsystems, but when Oracle acquired Sun, ZFS became a proprietary product. However, the FreeBSD project is still developing and improving its ZFS implementation via the OpenZFS project. Security FreeBSD provides several security-related features including access-control lists (ACLs), security event auditing, extended file system attributes, mandatory access controls (MAC) and fine-grained capabilities. These security enhancements were developed by the TrustedBSD project. The project was founded by Robert Watson with the goal of implementing concepts from the Common Criteria for Information Technology Security Evaluation and the Orange Book. This project is ongoing and many of its extensions have been integrated into FreeBSD. The project is supported by a variety of organizations, including the DARPA, NSA, Network Associates Laboratories, Safeport Network Services, the University of Pennsylvania, Yahoo!, McAfee Research, SPARTA, Apple Computer, nCircle Network Security, Google, the University of Cambridge Computer Laboratory, and others. The project has also ported the NSA's FLASK/TE implementation from SELinux to FreeBSD. Other work includes the development of OpenBSM, an open-source implementation of Sun's Basic Security Module (BSM) API and audit log file format, which supports an extensive security audit system. This was shipped as part of FreeBSD 6.2. Other infrastructure work in FreeBSD performed as part of the TrustedBSD Project has included GEOM and OpenPAM. Most components of the TrustedBSD project are eventually folded into the main sources for FreeBSD. In addition, many features, once fully matured, find their way into other operating systems. For example, OpenPAM has been adopted by NetBSD. Moreover, the TrustedBSD MAC Framework has been adopted by Apple for macOS. FreeBSD ships with three different firewall packages: IPFW, pf and IPFilter. IPFW is FreeBSD's native firewall. pf was taken from OpenBSD and IPFilter was ported to FreeBSD by Darren Reed. Taken from OpenBSD, the OpenSSH program was included in the default install. OpenSSH is a free implementation of the SSH protocol and is a replacement for telnet. Unlike telnet, OpenSSH encrypts all information (including usernames and passwords). In November 2012, The FreeBSD Security Team announced that hackers gained unauthorized access on two of the project's servers. These servers were turned off immediately. More research demonstrated that the first unauthorized access by hackers occurred on 19 September. Apparently hackers gained access to these servers by stealing SSH keys from one of the developers, not by exploiting a bug in the operating system itself. These two hacked servers were part of the infrastructure used to build third-party software packages. The FreeBSD Security Team checked the integrity of the binary packages and announced that no unauthorized changes were made to the binary packages, but stated that they could not guarantee the integrity of packages that were downloaded between 19 September and 11 November. Portability FreeBSD has been ported to a variety of instruction set architectures. The FreeBSD project organizes architectures into tiers that characterize the level of support provided. Tier 1 architectures are mature and fully supported, e.g. it is the only tier "supported by the security officer". Tier 3 architectures are experimental or are no longer under active development and Tier 4 architectures have no support at all. , FreeBSD has been ported to the following architectures: The 32-bit ARM (including OTG) and MIPS support is mostly aimed at embedded systems (ARM64 is also aimed at servers), however FreeBSD/ARM runs on a number of single-board computers, including the BeagleBone Black, Raspberry Pi and Wandboard. Hardware compatibility Supported devices are listed in the FreeBSD 12.1-RELEASE Hardware Notes. The document describes the devices currently known to be supported by FreeBSD. Other configurations may also work, but simply have not been tested yet. Rough automatically extracted lists of supported device ids are available in a third party repository. In 2020, a new project was introduced to automatically collect information about tested hardware configurations. Third-party software FreeBSD has a software repository of over 30,000 applications that are developed by third parties. Examples include: windowing systems, web browsers, email clients, office suites and so forth. In general, the project itself does not develop this software, only the framework to allow these programs to be installed, which is known as the Ports collection. Applications may either be compiled from source ("ports"), provided their licensing terms allow this, or downloaded as precompiled binaries ("packages"). The Ports collection supports the current and stable branches of FreeBSD. Older releases are not supported and may or may not work correctly with an up-to-date Ports collection. Ports use Makefiles to automatically fetch the desired application's source code, either from a local or remote repository, unpack it on the system, apply patches to it and compile it. Depending on the size of the source code, compiling can take a long time, but it gives the user more control over the process and its result. Most ports also have package counterparts (i.e. precompiled binaries), giving the user a choice. Although this method is faster, the user has fewer customization options. FreeBSD version 10.0 introduced the package manager pkg as a replacement for the previously used package tools. It is functionally similar to apt and yum in Linux distributions. It allows for installation, upgrading and removal of both ports and packages. In addition to pkg, PackageKit can also be used to access the Ports collection. Jails First introduced in FreeBSD version 4, jails are a security mechanism and an implementation of operating-system-level virtualization that enables the user to run multiple instances of a guest operating system on top of a FreeBSD host. It is an enhanced version of the traditional chroot mechanism. A process that runs within such a jail is unable to access the resources outside of it. Every jail has its own hostname and IP address. It is possible to run multiple jails at the same time, but the kernel is shared among all of them. Hence only software supported by the FreeBSD kernel can be run within a jail. Virtualization bhyve, a new virtualization solution, was introduced in FreeBSD 10.0. bhyve allows a user to run a number of guest operating systems (FreeBSD, OpenBSD, Linux, and Microsoft Windows) simultaneously. Other operating systems such as Illumos are planned. bhyve was written by Neel Natu and Peter Grehan and was announced in the 2011 BSDCan conference for the first time. The main difference between bhyve and FreeBSD jails is that jails are an operating system-level virtualization and therefore limited to only FreeBSD guests; but bhyve is a type 2 hypervisor and is not limited to only FreeBSD guests. For comparison, bhyve is a similar technology to KVM whereas jails are closer to LXC containers or Solaris Zones. Amazon EC2 AMI instances are also supported via amazon-ssm-agent Since FreeBSD 11.0, there has been support for running as the Dom0 privileged domain for the Xen type 1 hypervisor. Support for running as DomU (guest) has been available since FreeBSD 8.0. VirtualBox (without the closed-source Extension Pack) and QEMU are available on FreeBSD. OS compatibility layers Most software that runs on Linux can run on FreeBSD using an optional built-in compatibility layer. Hence, most Linux binaries can be run on FreeBSD, including some proprietary applications distributed only in binary form. This compatibility layer is not an emulation; Linux's system call interface is implemented in the FreeBSD's kernel and hence, Linux executable images and shared libraries are treated the same as FreeBSD's native executable images and shared libraries. Additionally, FreeBSD provides compatibility layers for several other Unix-like operating systems, in addition to Linux, such as BSD/OS and SVR4, however, it is more common for users to compile those programs directly on FreeBSD. No noticeable performance penalty over native FreeBSD programs has been noted when running Linux binaries, and, in some cases, these may even perform more smoothly than on Linux. However, the layer is not altogether seamless, and some Linux binaries are unusable or only partially usable on FreeBSD. There is support for system calls up to version 2.6.18, available since . As of release 10.3, FreeBSD can run 64-bit Linux binaries. FreeBSD has implemented a number of Microsoft Windows native NDIS kernel interfaces to allow FreeBSD to run (otherwise) Windows-only network drivers. The Wine compatibility layer, which allows the running of many Windows applications, especially games, without a (licensed) copy of Microsoft Windows, is available for FreeBSD. Kernel FreeBSD's kernel provides support for some essential tasks such as managing processes, communication, booting and filesystems. FreeBSD has a monolithic kernel, with a modular design. Different parts of the kernel, such as drivers, are designed as modules. The user can load and unload these modules at any time. ULE is the default scheduler in FreeBSD since version 7.1, it supports SMP and SMT. The FreeBSD kernel has also a scalable event notification interface, named kqueue. It has been ported to other BSD-derivatives such as OpenBSD and NetBSD. Kernel threading was introduced in FreeBSD 5.0, using an M:N threading model. This model works well in theory, but it is hard to implement and few operating systems support it. Although FreeBSD's implementation of this model worked, it did not perform well, so from version 7.0 onward, FreeBSD started using a 1:1 threading model, called libthr. Documentation and support FreeBSD's documentation consists of its handbooks, manual pages, mailing list archives, FAQs and a variety of articles, mainly maintained by The FreeBSD Documentation Project. FreeBSD's documentation is translated into several languages. All official documentation is released under the FreeBSD Documentation License, "a permissive non-copyleft free documentation license that is compatible with the GNU FDL". FreeBSD's documentation is described as "high-quality". The FreeBSD project maintains a variety of mailing lists. Among the most popular mailing lists are FreeBSD-questions (general questions) and FreeBSD-hackers (a place for asking more technical questions). Since 2004, the New York City BSD Users Group database provides dmesg information from a collection of computers (laptops, workstations, single-board computers, embedded systems, virtual machines, etc.) running FreeBSD. Installers From version 2.0 to 8.4, FreeBSD used the sysinstall program as its main installer. It was written in C by Jordan Hubbard. It uses a text user interface, and is divided into a number of menus and screens that can be used to configure and control the installation process. It can also be used to install Ports and Packages as an alternative to the command-line interface. The sysinstall utility is now considered deprecated in favor of bsdinstall, a new installer which was introduced in FreeBSD 9.0. bsdinstall is "a lightweight replacement for sysinstall" that was written in sh. According to OSNews, "It has lost some features while gaining others, but it is a much more flexible design, and will ultimately be significant improvement". Shell The default FreeBSD shell is the tcsh shell for root, and the Almquist shell (sh) for regular users. The default scripting shell is the Almquist shell. Development FreeBSD is developed by a volunteer team located around the world. The developers use the Internet for all communication and many have not met each other in person. In addition to local user groups sponsored and attended by users, an annual conference, called BSDcon, is held by USENIX. BSDcon is not FreeBSD-specific so it deals with the technical aspects of all BSD-derived operating systems, including OpenBSD and NetBSD. In addition to BSDcon, three other annual conferences, EuroBSDCon, AsiaBSDCon and BSDCan take place in Europe, Japan and Canada respectively. Governance structure The FreeBSD Project is run by around 500 committers or developers who have commit access to the master source code repositories and can develop, debug or enhance any part of the system. Most of the developers are volunteers and few developers are paid by some companies. There are several kinds of committers, including source committers (base operating system), doc committers (documentation and website authors) and ports (third-party application porting and infrastructure). Every two years the FreeBSD committers select a 9-member FreeBSD Core Team, which is responsible for overall project direction, setting and enforcing project rules and approving new committers, or the granting of commit access to the source code repositories. A number of responsibilities are officially assigned to other development teams by the FreeBSD Core Team, for example, responsibility for managing the ports collection is delegated to the Ports Management Team. In addition to developers, FreeBSD has thousands of "contributors". Contributors are also volunteers outside of the FreeBSD project who submit patches for consideration by committers, as they don't have direct access to FreeBSD's source code repository. Committers then evaluate contributors' submissions and decide what to accept and what to reject. A contributor who submits high-quality patches is often asked to become a committer. Branches FreeBSD developers maintain at least two branches of simultaneous development. The -CURRENT branch always represents the "bleeding edge" of FreeBSD development. A -STABLE branch of FreeBSD is created for each major version number, from which -RELEASE is cut about once every 4–6 months. If a feature is sufficiently stable and mature it will likely be backported (MFC or Merge from CURRENT in FreeBSD developer slang) to the -STABLE branch. Foundation FreeBSD development is supported in part by the FreeBSD Foundation. The foundation is a non-profit organization that accepts donations to fund FreeBSD development. Such funding has been used to sponsor developers for specific activities, purchase hardware and network infrastructure, provide travel grants to developer summits, and provide legal support to the FreeBSD project. In November 2014, the FreeBSD Foundation received US$1 million donation from Jan Koum, Co-Founder and CEO of WhatsApp the largest single donation to the Foundation since its inception. In December 2016, Jan Koum donated another 500 thousand dollars. Jan Koum himself is a FreeBSD user since the late 1990s and WhatsApp uses FreeBSD on its servers. License FreeBSD is released under a variety of open-source licenses. The kernel code and most newly-created code are released under the two-clause BSD license which allows everyone to use and redistribute FreeBSD as they wish. This license was approved by Free Software Foundation and Open Source Initiative as a Free Software and Open Source license respectively. Free Software Foundation described this license as "a lax, permissive non-copyleft free software license, compatible with the GNU GPL". There are parts released under three- and four-clause BSD licenses, as well as the Beerware license. Some device drivers include a binary blob, such as the Atheros HAL of FreeBSD versions before 7.2. Some of the code contributed by other projects is licensed under GPL, LGPL, CDDL and ISC. All the code licensed under GPL and CDDL is clearly separated from the code under liberal licenses, to make it easy for users such as embedded device manufacturers to use only permissive free software licenses. ClangBSD aims to replace some GPL dependencies in the FreeBSD base system by replacing the GNU compiler collection with the BSD-licensed LLVM/Clang compiler. ClangBSD became self-hosting on 16 April 2010. Logo For many years FreeBSD's logo was the generic BSD Daemon, also called Beastie, a distorted pronunciation of BSD. However, Beastie was not unique to FreeBSD. First appearing in 1976 on Unix T-shirts purchased by Bell Labs, the more popular versions of the BSD daemon were drawn by animation director John Lasseter beginning in 1984. Several FreeBSD-specific versions were later drawn by Tatsumi Hosokawa. In lithographic terms, the Lasseter graphic is not line art and often requires a screened, four-color photo offset printing process for faithful reproduction on physical surfaces such as paper. Also, the BSD daemon was thought to be too graphically detailed for smooth size scaling and aesthetically over-dependent on multiple color gradations, making it hard to reliably reproduce as a simple, standardized logo in only two or three colors, much less in monochrome. Because of these worries, a competition was held and a new logo designed by Anton K. Gural, still echoing the BSD daemon, was released on 8 October 2005. However, it was announced by Robert Watson that the FreeBSD project is "seeking a new logo, but not a new mascot" and that the FreeBSD project would continue to use Beastie as its mascot. The name "FreeBSD" was coined by David Greenman on 19 June 1993, other suggested names were "BSDFree86" and "Free86BSD". FreeBSD's slogan, "The Power to Serve", is a trademark of The FreeBSD Foundation. Derivatives There are a number of software distributions based on FreeBSD. Notable derivatives include: DesktopBSD (desktop-oriented operating system, originally based on KDE) TrueNAS (for network-attached storage devices) FreeSBIE (live CD) GhostBSD (MATE-based distribution, which also offers other desktop environments) MidnightBSD NanoBSD PicoBSD IntelliStar (satellite system that runs TV programs such as Weatherscan and Local On The 8s) m0n0wall (firewall) OpenServer 10 (server) OPNsense (firewall) pfSense (firewall) TrueOS, previously known as PC-BSD (aimed at home users and workstations, but with a FreeNAS-like server version and TrueOS pico for ARM 32-bit embedded devices) TrustedBSD XigmaNAS (for network-attached storage devices) All these distributions have no or only minor changes when compared with the original FreeBSD base system. The main difference to the original FreeBSD is that they come with pre-installed and pre-configured software for specific use cases. This can be compared with Linux distributions, which are all binary compatible because they use the same kernel and also use the same basic tools, compilers, and libraries while coming with different applications, configurations, and branding. Besides these distributions, there are some independent operating systems based on FreeBSD. DragonFly BSD is a fork from FreeBSD 4.8 aiming for a different multiprocessor synchronization strategy than the one chosen for FreeBSD 5 and development of some microkernel features. It does not aim to stay compatible with FreeBSD and has huge differences in the kernel and basic userland. MidnightBSD is a fork of FreeBSD 6.1 borrowing heavily from NeXTSTEP, particularly in the user interface department. Darwin, the core of Apple's macOS, includes a virtual file system and network stack derived from those of FreeBSD, and components of its userspace are also FreeBSD-derived. Some subscription services that are directly based on FreeBSD are: WhatsApp processes 2 million concurrent TCP connections per server. Embedded devices and embedded device operating systems based on FreeBSD include: Juniper's JUNOS router operating system. EMC Isilon's OneFS operating system. NetApp's Data ONTAP 8.x and the now-superseded ONTAP GX (only as a loader for proprietary kernel-space module). Netflix's Open Connect Appliance to handle content delivery. The PlayStation 4 ("Orbis OS") Panasas' PanFS parallel file system pfSense, an open-source firewall, router and security appliance operating system. Version history See also BAPP, a set of commonly used software with FreeBSD Berkeley Software Distribution Comparison of BSD operating systems Comparison of operating system kernels Comparison of operating systems Computer Systems Research Group Marshall Kirk McKusick References Citations Sources External links FreeBSD on DistroWatch FreeBSD on OpenSourceFeed Gallery 1993 software ARM operating systems Computing platforms Lightweight Unix-like systems PowerPC operating systems Software using the BSD license IA-32 operating systems X86-64 operating systems

Operating System (OS)

Olivetti X/OS X/OS was a Unix from the computer manufacturer Olivetti. It was based on 4.2BSD with some UNIX System V support. It ran on their LSX line of computers, which was based on the Motorola 68000-series CPUs. Unix variants

Operating System (OS)

RISC OS RISC OS is a computer operating system originally designed by Acorn Computers Ltd in Cambridge, England. First released in 1987, it was designed to run on the ARM chipset, which Acorn had designed concurrently for use in its new line of Archimedes personal computers. RISC OS takes its name from the reduced instruction set computer (RISC) architecture it supports. Between 1987 and 1998, RISC OS was included in every ARM-based Acorn computer model, including the Acorn Archimedes line, Acorn's R line (with RISC iX as a dual-boot option), RiscPC, A7000, and prototype models such as the Acorn NewsPad and Phoebe computer. A version of the OS, named NCOS, was used in Oracle Corporation's Network Computer and compatible systems. After the break-up of Acorn in 1998, development of the OS was forked and continued separately by several companies, including , Pace Micro Technology, and Castle Technology. Since then, it has been bundled with several ARM-based desktop computers such as the Iyonix PC and A9home. , the OS remains forked and is independently developed by and the community. Most recent stable versions run on the ARMv3/ARMv4 RiscPC, the ARMv5 Iyonix, ARMv7 Cortex-A8 processors (such as that used in the BeagleBoard and Touch Book) and Cortex-A9 processors (such as that used in the PandaBoard) and the low-cost educational Raspberry Pi computer. SD card images have been released for downloading free of charge to Raspberry Pi 1, 2, 3, & 4 users with a full graphical user interface (GUI) version and a command-line interface only version (RISC OS Pico, at 3.8 MB). History RISC OS was originally released in 1987 as Arthur 1.20. The next version, , became and was released in April 1989. RISC OS 3.00 was released with the A5000 in 1991, and contained many new features. By 1996, RISC OS had been shipped on over 500,000 systems. Acorn officially halted work on the OS in January 1999, renaming themselves Element 14. In March 1999 a new company, RISCOS Ltd, licensed the rights to develop a desktop version of RISC OS from Element 14, and continued the development of RISC OS 3.8, releasing it as RISC OS 4 in July 1999. Meanwhile, Element 14 had also kept a copy of RISC OS 3.8 in house, which they developed into NCOS for use in set-top boxes. In 2000, Element 14 sold RISC OS to Pace Micro Technology, who later sold it to Castle Technology Ltd. In May 2001, RISCOS Ltd launched RISC OS Select, a subscription scheme allowing users access to the latest RISC OS 4 updates. These upgrades are released as soft-loadable ROM images, separate to the ROM where the boot OS is stored, and are loaded at boot time. Select 1 was shipped in May 2002, with Select 2 following in November 2002 and the final release of Select 3 in June 2004. In the same month, RISC OS 4.39, dubbed RISC OS Adjust, was released. RISC OS Adjust was a culmination of all the Select Scheme updates to date, released as a physical set of replaceable ROMs for the RiscPC and A7000 series of machines. Meanwhile, in October 2002, Castle Technology released the Acorn clone Iyonix PC. This ran a 32-bit (in contrast to 26-bit) variant of RISC OS, named RISC OS 5. RISC OS 5 is a separate evolution of RISC OS based upon the NCOS work done by Pace. The following year, Castle Technology bought RISC OS from Pace for an undisclosed sum. In October 2006, Castle announced a shared source license plan, managed by RISC OS Open Limited, for elements of RISC OS 5. In October 2018, RISC OS 5 was re-licensed under the Apache 2.0 license. In December 2020, the source code of RISC OS 3.71 was leaked to The Pirate Bay. Supported hardware Versions of RISC OS run or have run on the following hardware. RISC OS Open Limited adopted the 'even numbers are stable' version numbering scheme post version 5.14, hence some table entries above include two latest releases – the last stable one and the more recent development one. A special cut down RISC OS Pico (for 16MiB cards and larger) styled to start up like a BBC Micro was released for BASIC's 50th anniversary. RISC OS has also been used by both Acorn and Pace Micro Technology in various TV connected set-top boxes, sometimes referred to instead as NCOS. RISC OS can also run on a range of computer system emulators that emulate the earlier Acorn machines listed above. Features OS core The OS is single-user and employs cooperative multitasking (CMT). While most current desktop OSes use preemptive multitasking (PMT) and multithreading, remains with a CMT system. By 2003, many users had called for the OS to migrate to PMT. The OS memory protection is not comprehensive. The core of the OS is stored in ROM, giving a fast bootup time and safety from operating system corruption. RISC OS 4 and 5 are stored in of flash memory, or as a ROM image on SD Card on single board computers such as the Beagleboard or Raspberry Pi, allowing the operating system to be updated without having to replace the ROM chip. The OS is made up of several modules. These can be added to and replaced, including soft-loading of modules not present in ROM at run time and on-the-fly replacement. This design has led to OS developers releasing rolling updates to their versions of the OS, while third parties are able to write OS replacement modules to add new features. OS modules are accessed via software interrupts (SWIs), similar to system calls in other operating systems. Most of the OS has defined application binary interfaces (ABIs) to handle filters and vectors. The OS provides many ways in which a program can intercept and modify its operation. This simplifies the task of modifying its behaviour, either in the GUI, or deeper. As a result, there are several third-party programs which allow customising the OS look and feel. File system The file system is volume-oriented: the top level of the file hierarchy is a volume (disc, network share) prefixed by the file system type. To determine file type, the OS uses metadata instead of file extensions. Colons are used to separate the file system from the rest of the path; the root is represented by a dollar ($) sign and directories are separated by a full stop (.). Extensions from foreign file systems are shown using a slash (example.txt becomes example/txt). For example, ADFS::HardDisc4.$ is the root of the disc named HardDisc4 using the Advanced Disc Filing System (ADFS) file system. filetypes can be preserved on other systems by appending the hexadecimal type as ',xxx' to filenames. When using cross-platform software, filetypes can be invoked on other systems by naming appending '/[extension]' to the filename under . A file system can present a file of a given type as a volume of its own, similar to a loop device. The OS refers to this function as an image filing system. This allows transparent handling of archives and similar files, which appear as directories with some special properties. Files inside the image file appear in the hierarchy underneath the parent archive. It is not necessary for the archive to contain the data it refers to: some symbolic link and network share file systems put a reference inside the image file and go elsewhere for the data. The file system abstraction layer API uses 32-bit file offsets, making the largest single file 4 GiB (minus 1 byte) long. However, prior to RISC OS 5.20 the file system abstraction layer and many RISC OS-native file systems limited support to 31 bits (just under 2 GiB) to avoid dealing with apparently negative file extents when expressed in two's complement notation. File formats The OS uses metadata to distinguish file formats. Some common file formats from other systems are mapped to filetypes by the MimeMap module. Kernel The RISC OS kernel is single-tasking and controls handling of interrupts, DMA services, memory allocation and the video display; the cooperative multi-tasking is provided by the WindowManager module. Desktop The WIMP interface is based on a stacking window manager and incorporates three mouse buttons (named Select, Menu and Adjust), context-sensitive menus, window order control (i.e. send to back) and dynamic window focus (a window can have input focus at any position on the stack). The icon bar (Dock) holds icons which represent mounted disc drives, RAM discs, running applications, system utilities and docked: files, directories or inactive applications. These icons have context-sensitive menus and support drag-and-drop operation. They represent the running application as a whole, irrespective of whether it has open windows. The GUI functions on the concept of files. The Filer, a spatial file manager, displays the contents of a disc. Applications are run from the Filer view and files can be dragged to the Filer view from applications to perform saves. Application directories are used to store applications. The OS differentiates them from normal directories through the use of an exclamation mark (also called a pling or shriek) prefix. Double-clicking on such a directory launches the application rather than opening the directory. The application's executable files and resources are contained within the directory, but normally they remain hidden from the user. Because applications are self-contained, this allows drag-and-drop installing and removing. The Style Guide encourages a consistent look and feel across applications. This was introduced in and specifies application appearance and behaviour. Acorn's own main bundled applications were not updated to comply with the guide until 's Select release in 2001. Font manager RISC OS was the first operating system to provide scalable anti-aliased fonts. Anti-aliased fonts were already familiar from Arthur, and their presence in RISC OS was confirmed in an early 1989 preview, featuring in the final RISC OS 2 product, launched in April 1989. A new version of the font manager employing "new-style outline fonts" was made available after the release of RISC OS, offering full support for the printing of scalable fonts, and was provided with Acorn Desktop Publisher. It was also made available separately and bundled with other applications. This outline font manager provides support for the rendering of font outlines to bitmaps for screen and printer use, employing anti-aliasing for on-screen fonts, utilising sub-pixel anti-aliasing and caching for small font sizes. At the time of the introduction of Acorn's outline font manager, the developers of rival desktop systems were either contemplating or promising outline font support for still-unreleased products such as Macintosh System 7 and OS/2 version 2. Since 1994, in RISC OS 3.5, it has been possible to use an outline anti-aliased font in the WindowManager for UI elements, rather than the bitmap system font from previous versions. RISC OS 4 does not support Unicode but "RISC OS 5 provides a Unicode Font Manager which is able to display Unicode characters and accept text in UTF-8, UTF-16 and UTF-32. Other parts of the RISC OS kernel and core modules support text described in UTF-8." Support for the characters of RISC OS (and some other historic computers) was added to Unicode 13.0 (in 2020). Bundled applications is available in several distributions, all of which include a small standard set of desktop applications, but some of which also include a much wider set of useful programs. Some of those richer distributions are freely available, some are paid for. Backward compatibility Limited software portability exists with subsequent versions of the OS and hardware. Single-tasking BBC BASIC applications often require only trivial changes, if any. Successive OS upgrades have raised more serious issues of backward compatibility for desktop applications and games. Applications still being maintained by their author(s) or others have sometimes historically been amended to provide compatibility. The introduction of the RiscPC in 1994 and its later StrongARM upgrade raised issues of incompatible code sequences and proprietary squeezing (data compression). Patching of applications for the StrongARM was facilitated and Acorn's UnsqueezeAIF software unsqueezed images according to their AIF header. The incompatibilities prompted release by The ARM Club of its Game On! and StrongGuard software. They allowed some formerly incompatible software to run on new and upgraded systems. The version of the OS for the A9home prevented the running of software without an AIF header (in accord with Application Note 295) to stop "trashing the desktop". The Iyonix PC () and A9home (custom ) saw further software incompatibility because of the deprecated addressing modes. Most applications under active development have since been rewritten. Static code analysis to detect -only sequences can be undertaken using ARMalyser. Its output can be helpful in making 32-bit versions of older applications for which the source code is unavailable. Some older 26-bit software can be run without modification using the Aemulor emulator. Additional incompatibilities were introduced with newer ARM cores, such as ARMv7 in the BeagleBoard and ARMv8 in the . This includes changes to unaligned memory access in ARMv6/v7 and removal of the SWP instructions in ARMv8. See also Acorn C/C++ ArtWorks Drobe riscos.info ROX Desktop, a graphical desktop environment for the X Window System, inspired by the user interface of RISC OS Sibelius (scorewriter), originally an application for RISC OS, rewritten for Windows in 1998 RISC OS character set References External links RISC OS Open Acorn operating systems ARM operating systems Desktop environments Free software operating systems Software using the Apache license Window-based operating systems 1987 software

Operating System (OS)

OpenSolaris OpenSolaris (”) is a discontinued open-source computer operating system based on Solaris and created by Sun Microsystems. It was also (confusingly) the name of a project initiated by Sun to build a developer and user community around the eponymous operating system software. OpenSolaris is a descendant of the UNIX System V Release 4 (SVR4) code base developed by Sun and AT&T in the late 1980s and is the only version of the System V variant of UNIX available as open source. OpenSolaris was developed as a combination of several software consolidations that were open sourced starting with Solaris 10. It includes a variety of free software, including popular desktop and server software. After Oracle’s acquisition of Sun Microsystems in 2010, Oracle discontinued development of OpenSolaris in house, pivoting to focus exclusively on the development of the proprietary Solaris Express (now Oracle Solaris). Prior to Oracle's close-sourcing Solaris, a group of former OpenSolaris developers began efforts to fork the core software under the name OpenIndiana. The illumos Foundation, founded in the wake of the discontinuation of OpenSolaris, continues to develop and maintain the kernel and userland of OpenIndiana (together renamed “illumos”), while the OpenIndiana Project (now under the auspices of the illumos Foundation) continues to maintain and develop the illumos-based OpenIndiana distribution (including its installer and build system) as the direct descendant of OpenIndiana. Since then additional illumos distributions, both commercial and non-commercial, have appeared and are under active development, combining the illumos kernel and userland with custom installers, packaging and build systems, and other distribution-specific utilities and tooling. History OpenSolaris was based on Solaris, which was originally released by Sun in 1991. Solaris is a version of UNIX System V Release 4 (SVR4), jointly developed by Sun and AT&T to merge features from several existing Unix systems. It was licensed by Sun from Novell to replace SunOS. Planning for OpenSolaris started in early 2004. A pilot program was formed in September 2004 with 18 non-Sun community members and ran for 9 months growing to 145 external participants. Sun submitted the CDDL (Common Development and Distribution License) to the OSI, which approved it on January 14, 2005. The first part of the Solaris code base to be open sourced was the Solaris Dynamic Tracing facility (commonly known as DTrace), a tool that aids in the analysis, debugging, and tuning of applications and systems. DTrace was released under the CDDL on January 25, 2005, on the newly launched opensolaris.org website. The bulk of the Solaris system code was released on June 14, 2005. There remains some system code that is not open sourced, and is available only as pre-compiled binary files. To direct the newly fledged project, a Community Advisory Board was announced on April 4, 2005: two were elected by the pilot community, two were employees appointed by Sun, and one was appointed from the broader free software community by Sun. The members were Roy Fielding, Al Hopper, Rich Teer, Casper Dik, and Simon Phipps. On February 10, 2006 Sun approved The OpenSolaris Charter, which reestablished this body as the independent OpenSolaris Governing Board. The task of creating a governance document or "constitution" for this organization was given to the OGB and three invited members: Stephen Hahn and Keith Wesolowski (developers in Sun's Solaris organization) and Ben Rockwood (a prominent OpenSolaris community member). The former next-generation Solaris OS version under development by Sun to eventually succeed Solaris 10 was codenamed 'Nevada', and was derived from what was the OpenSolaris codebase and this new code was then pulled into new OpenSolaris 'Nevada' snapshot builds. "While under Sun Microsystems' control, there were bi-weekly snapshots of Solaris Nevada (the codename for the next-generation Solaris OS to eventually succeed Solaris 10) and this new code was then pulled into new OpenSolaris preview snapshots available at Genunix.org. The stable releases of OpenSolaris are based on these Nevada builds." Initially, Sun's Solaris Express program provided a distribution based on the OpenSolaris code in combination with software found only in Solaris releases. The first independent distribution was released on June 17, 2005, and many others have emerged since. On March 19, 2007, Sun announced that it had hired Ian Murdock, founder of Debian, to head Project Indiana, an effort to produce a complete OpenSolaris distribution, with GNOME and userland tools from GNU, plus a network-based package management system. The new distribution was planned to refresh the user experience, and would become the successor to Solaris Express as the basis for future releases of Solaris. On May 5, 2008, OpenSolaris 2008.05 was released in a format that could be booted as a Live CD or installed directly. It uses the GNOME desktop environment as the primary user interface. The later OpenSolaris 2008.11 release included a GUI for ZFS' snapshotting capabilities, known as Time Slider, that provides functionality similar to macOS's Time Machine. In December 2008, Sun Microsystems and Toshiba America Information Systems announced plans to distribute Toshiba laptops pre-installed with OpenSolaris. On April 1, 2009, the Tecra M10 and Portégé R600 came preinstalled with OpenSolaris 2008.11 release and several supplemental software packages. On June 1, 2009, OpenSolaris 2009.06 was released, with support for the SPARC platform. On January 6, 2010, it was announced that Solaris Express program would be closed while an OpenSolaris binary release was scheduled to be released March 26, 2010. The OpenSolaris 2010.03 release never appeared. On August 13, 2010, Oracle was rumored to have discontinued the OpenSolaris binary distribution to focus on the Solaris Express binary distribution program. Source code would continue to be accepted from the community and Oracle source code would continue to be released into Open Source, but Oracle code releases would occur only after binary releases. Internal email was released by an OpenSolaris kernel developer but was unconfirmed by Oracle. There was a post confirming the leak posted to the OpenSolaris Forums on August 13, 2010. Upstream contributions will continue through a new Oracle web site, downstream source code publishing will continue, binary distribution will continue under the old Solaris Express model, but release of source code will occur after binary cuts, and binary cuts will become less frequent. On September 14, 2010, OpenIndiana was formally launched at the JISC Centre in London. While OpenIndiana is a fork in the technical sense, it is a continuation of OpenSolaris in spirit: the project intends to deliver a System V family operating system which is binary-compatible with the Oracle products Solaris 11 and Solaris 11 Express. However, rather than being based around the OS/Net consolidation like OpenSolaris was, OpenIndiana became a distribution based on illumos (the first release is still based around OS/Net). The project uses the same IPS package management system as OpenSolaris. On November 12, 2010, a final build of OpenSolaris (134b) was published by Oracle to the /release repository to serve as an upgrade path to Solaris 11 Express. Oracle Solaris 11 Express 2010.11, a preview of Solaris 11 and the first release of the post-OpenSolaris distribution from Oracle, was released on November 15, 2010. Version history Release model OpenSolaris was offered as both development (unstable) and production (stable) releases. Development releases were built from the latest OpenSolaris codebase (consolidations) and included newer technologies, security updates and bug fixes, and more applications, but may not have undergone extensive testing. Production releases were branched from a snapshot of the development codebase (following a code freeze) and underwent a QA process that includes backporting security updates and bug fixes. OpenSolaris can be installed from CD-ROM, USB drives, or over a network with the Automated Installer. CD, USB, and network install images are made available for both types of releases. Repositories OpenSolaris uses a network-aware package management system called the Image Packaging System (also known as pkg(5)) to add, remove, and manage installed software and to update to newer releases. Packages for development releases of OpenSolaris were published by Oracle typically every two weeks to the /dev repository. Production releases use the /release repository which does not receive updates until the next production release. Only Sun customers with paid support contracts have access to updates for production releases. Paid support for production releases which allows access to security updates and bug fixes was offered by Sun through the /support repository on pkg.sun.com. Documentation A hardware compatibility list (HCL) for OpenSolaris can be consulted when choosing hardware for OpenSolaris deployment. Extensive OpenSolaris administration, usage, and development documentation is available online, including community-contributed information. License Sun released most of the Solaris source code under the Common Development and Distribution License (CDDL), which is based on the Mozilla Public License (MPL) version 1.1. The CDDL was approved as an open source license by the Open Source Initiative (OSI) in January 2005. Files licensed under the CDDL can be combined with files licensed under other licenses, whether open source or proprietary. During Sun's announcement of Java's release under the GNU General Public License (GPL), Jonathan Schwartz and Rich Green both hinted at the possibility of releasing Solaris under the GPL, with Green saying he was "certainly not" averse to relicensing under the GPL. When Schwartz pressed him (jokingly), Green said Sun would "take a very close look at it." In January 2007, eWeek reported that anonymous sources at Sun had told them OpenSolaris would be dual-licensed under CDDL and GPLv3. Green responded in his blog the next day that the article was incorrect, saying that although Sun is giving "very serious consideration" to such a dual-licensing arrangement, it would be subject to agreement by the rest of the OpenSolaris community. Conferences The first annual OpenSolaris Developer Conference (abbreviated as OSDevCon) was organized by the German Unix User Group (GUUG) and took place from February 27 to March 2, 2007 at the Freie Universität Berlin in Germany. The 2008 OSDevCon was a joint effort of the GUUG and the Czech OpenSolaris User Group (CZOSUG) and look place June 25–27, 2008 in Prague, Czech Republic. The 2009 OSDevCon look place October 27–30, 2009, in Dresden, Germany. In 2007, Sun Microsystems organized the first OpenSolaris Developer Summit, which was held on the weekend of October 13, 2007, at the University of California, Santa Cruz in the United States. The 2008 OpenSolaris Developer Summit returned to UCSC on May 2–3, 2008, and took place immediately prior to the launch of Sun's new OpenSolaris distribution on May 5, 2008, at the CommunityOne conference in San Francisco, California. The first OpenSolaris Storage Summit was organized by Sun and held September 21, 2008, preceding the SNIA Storage Developer Conference (SDC), in Santa Clara, California. The second OpenSolaris Storage Summit preceded the USENIX Conference on File and Storage Technologies (FAST) on February 23, 2009, in San Francisco, United States. On November 3, 2009, a Solaris/OpenSolaris Security Summit was held by Sun in the Inner Harbor area of Baltimore, Maryland, preceding the Large Installation System Administration Conference (LISA). Ports PowerPC Port: Project Polaris, experimental PowerPC port, based on the previous porting effort, Project Pulsar from Sun Labs. OpenSolaris for System z, for IBM mainframes: Project Sirius, developed by Sine Nomine Associates, named as an analogy to Polaris. OpenSolaris on ARM Port OpenSolaris on MIPS Port Derivatives Notable derivatives include: illumos, a fully open source fork of the project, started in 2010 by a community of Sun OpenSolaris engineers and the NexentaOS support. Note that OpenSolaris was not 100% open source: Some drivers and some libraries were property of other companies that Sun (now Oracle) licensed and was not able to release. OpenIndiana, a project under the illumos umbrella aiming "... to become the defacto OpenSolaris distribution installed on production servers where security and bug fixes are required free of charge." NexentaStor, optimized for storage workloads, based on Nexenta OS OSDyson: illumos kernel with GNU userland and packages from Debian. Strives to become an official Debian port. SmartOS: Virtualization-centered derivative from Joyent. Discontinued Nexenta OS (discontinued October 31, 2012), first distribution based on Ubuntu userland with Solaris-derived kernel See also Comparison of OpenSolaris distributions Comparison of open source operating systems Image Packaging System OpenSolaris Network Virtualization and Resource Control Darwin (operating system) References Further reading External links OpenSolaris archive and downloads OpenSolaris 2008 software Discontinued operating systems Formerly proprietary software Operating system distributions bootable from read-only media Software using the CDDL license Sun Microsystems software

Operating System (OS)

OpenBSD OpenBSD is a security-focused, free and open-source, Unix-like operating system based on the Berkeley Software Distribution (BSD). Theo de Raadt created OpenBSD in 1995 by forking NetBSD. According to the website, the OpenBSD project emphasizes "portability, standardization, correctness, proactive security and integrated cryptography." The OpenBSD project maintains portable versions of many subsystems as packages for other operating systems. Because of the project's preferred BSD license, many components are reused in proprietary and corporate-sponsored software projects. The firewall code in Apple's macOS is based on OpenBSD's PF firewall code, Android's Bionic C standard library is based on OpenBSD code, LLVM uses OpenBSD's regular expression library, and Windows 10 uses OpenSSH (OpenBSD Secure Shell) with LibreSSL. The word "open" in the name OpenBSD refers to the availability of the operating system source code on the Internet, although the word "open" in the name OpenSSH means "OpenBSD". It also refers to the wide range of hardware platforms the system supports. History In December 1994, Theo de Raadt, a founding member of the NetBSD project, was asked to resign from the NetBSD core team over disagreements and conflicts with the other members of the NetBSD team. In October 1995, De Raadt founded OpenBSD, a new project forked from NetBSD 1.0. The initial release, OpenBSD 1.2, was made in July 1996, followed by OpenBSD 2.0 in October of the same year. Since then, the project has issued a release every six months, each of which is supported for one year. On 25 July 2007, OpenBSD developer Bob Beck announced the formation of the OpenBSD Foundation, a Canadian non-profit organization formed to "act as a single point of contact for persons and organizations requiring a legal entity to deal with when they wish to support OpenBSD." Usage statistics It is hard to determine how widely OpenBSD is used, because the developers do not publish or collect usage statistics. In September 2005, the BSD Certification Group surveyed 4330 individual BSD users, showing that 32.8% used OpenBSD, behind FreeBSD with 77%, ahead of NetBSD with 16.3% and DragonFly BSD with 2.6%. However, the authors of this survey clarified that it is neither "exhaustive" nor "completely accurate", since the survey was spread mainly through mailing lists, forums and word of mouth. This combined with other factors, like the lack of a control group, a pre-screening process or significant outreach outside of the BSD community, makes the survey unreliable for judging BSD usage globally. Uses Network appliances OpenBSD features a robust TCP/IP networking stack, and can be used as a router or wireless access point. OpenBSD's security enhancements, built-in cryptography, and packet filter make it suitable for security purposes such as firewalls, intrusion-detection systems, and VPN gateways. Several proprietary systems are based on OpenBSD, including devices from Armorlogic (Profense web application firewall), Calyptix Security, GeNUA, RTMX, and .vantronix. Foreign operating systems Some versions of Microsoft's Services for UNIX, an extension to the Windows operating system to provide Unix-like functionality, use much of the OpenBSD code base that is included in the Interix interoperability suite, developed by Softway Systems Inc., which Microsoft acquired in 1999. Core Force, a security product for Windows, is based on OpenBSD's pf firewall. The pf firewall is also found in other operating systems: including FreeBSD, and macOS. Personal computers OpenBSD ships with Xenocara, an implementation of the X Window System, and is suitable as a desktop operating system for personal computers, including laptops. , OpenBSD includes approximately 8000 packages in its software repository, including desktop environments such as GNOME, Plasma 4, and Xfce, and web browsers such as Firefox and Chromium. The project also includes three window managers in the main distribution: cwm, FVWM (part of the default configuration for Xenocara), and twm. Servers OpenBSD features a full server suite and can be configured as a mail server, web server, FTP server, DNS server, router, firewall, NFS file server, or any combination of these. Since version 6.8, OpenBSD has also shipped with native in-kernel WireGuard support. Security Shortly after OpenBSD was created, De Raadt was contacted by a local security software company named Secure Networks (later acquired by McAfee). They were developing a network security auditing tool called Ballista, which was intended to find and exploit software security flaws. This coincided with De Raadt's interest in security, so the two cooperated leading up to the release of OpenBSD 2.3. This collaboration helped to define security as the focus of the OpenBSD project. OpenBSD includes numerous features designed to improve security, such as: Secure alternatives to POSIX functions in the C standard library, such as strlcat for strcat and strlcpy for strcpy Toolchain alterations, including a static bounds checker Memory protection techniques to guard against invalid accesses, such as ProPolice and the W^X page protection feature Strong cryptography and randomization System call and filesystem access restrictions to limit process capabilities To reduce the risk of a vulnerability or misconfiguration allowing privilege escalation, many programs have been written or adapted to make use of privilege separation, privilege revocation and chrooting. Privilege separation is a technique, pioneered on OpenBSD and inspired by the principle of least privilege, where a program is split into two or more parts, one of which performs privileged operations and the other—almost always the bulk of the code—runs without privilege. Privilege revocation is similar and involves a program performing any necessary operations with the privileges it starts with then dropping them. Chrooting involves restricting an application to one section of the file system, prohibiting it from accessing areas that contain private or system files. Developers have applied these enhancements to OpenBSD versions of many common applications, such as tcpdump, file, tmux, smtpd, and syslogd. OpenBSD developers were instrumental in the creation and development of OpenSSH (aka OpenBSD Secure Shell), which is developed in the OpenBSD CVS repositories. OpenBSD Secure Shell is based on the original SSH. It first appeared in OpenBSD 2.6 and is now by far the most popular SSH client and server, available on many operating systems. The project has a policy of continually auditing source code for problems, work that developer Marc Espie has described as "never finished ... more a question of process than of a specific bug being hunted." He went on to list several typical steps once a bug is found, including examining the entire source tree for the same and similar issues, "try[ing] to find out whether the documentation ought to be amended", and investigating whether "it's possible to augment the compiler to warn against this specific problem." Security record The OpenBSD website features a prominent reference to the system's security record. Until June 2002, it read: In June 2002, Mark Dowd of Internet Security Systems disclosed a bug in the OpenSSH code implementing challenge–response authentication. This vulnerability in the OpenBSD default installation allowed an attacker remote access to the root account, which was extremely serious not only to OpenBSD, but also to the large number of other operating systems that were using OpenSSH by that time. This problem necessitated the adjustment of the slogan on the OpenBSD website to: The quote remained unchanged as time passed, until on 13 March 2007, when Alfredo Ortega of Core Security Technologies disclosed a network-related remote vulnerability. The quote was subsequently changed to: This statement has been criticized because the default install contains few running services, and many use cases require additional services. Also, because the ports tree contains unaudited third-party software, it is easy for users to compromise security by installing or improperly configuring packages. However, the project maintains that the slogan is intended to refer to a default install and that it is correct by that measure. One of the fundamental ideas behind OpenBSD is a drive for systems to be simple, clean, and secure by default. The default install is quite minimal, which the project states is to ensure novice users "do not need to become security experts overnight", which fits with open-source and code auditing practices considered important elements of a security system. Alleged backdoor On 11 December 2010, Gregory Perry, a former technical consultant for the Federal Bureau of Investigation (FBI), emailed De Raadt alleging that the FBI had paid some OpenBSD ex-developers 10 years prior to insert backdoors into the OpenBSD Cryptographic Framework. De Raadt made the email public on 14 December by forwarding it to the openbsd-tech mailing list and suggested an audit of the IPsec codebase. De Raadt's response was skeptical of the report and he invited all developers to independently review the relevant code. In the weeks that followed, bugs were fixed but no evidence of backdoors was found. De Raadt stated "I believe that NetSec was probably contracted to write backdoors as alleged. If those were written, I don't believe they made it into our tree. They might have been deployed as their own product." Criticisms In December 2017, Ilja van Sprundel, director at IOActive, gave a talk at the CCC as well as DEF CON, entitled "Are all BSDs created equally? — A survey of BSD kernel vulnerabilities", in which he stated that although OpenBSD was the clear winner of the BSDs in terms of security, "Bugs are still easy to find in those kernels, even in OpenBSD". Two years later, in 2019, a talk named "A systematic evaluation of OpenBSD's mitigations" was given at the CCC, arguing that while OpenBSD has some effective mitigations, a significant part of them are "useless at best and based on pure luck and superstition", arguing for a more rational approach when it comes to designing them. Hardware compatibility Supported platforms and devices are listed in the OpenBSD Supported Platforms Notes. Other configurations may also work, but simply have not been tested or documented yet. Rough automatically extracted lists of supported device ids are available in a third party repository. In 2020, a new project was introduced to automatically collect information about tested hardware configurations. Subprojects Many open source projects started as components of OpenBSD, including: bioctl, a generic RAID management interface similar to ifconfig CARP, a free alternative to Cisco's patented HSRP/VRRP redundancy protocols cwm, a stacking window manager doas, a safer replacement for sudo OpenBSD httpd, an implementation of httpd hw.sensors, a sensors framework used by over 100 drivers LibreSSL, an implementation of the SSL and TLS protocols, forked from OpenSSL 1.0.1g OpenBGPD, an implementation of BGP-4 OpenIKED, an implementation of IKEv2 OpenNTPD, a simpler alternative to ntp.org's NTP daemon OpenOSPFD, an implementation of OSPF OpenSMTPD, an SMTP daemon with IPv4/IPv6, PAM, Maildir, and virtual domains support OpenSSH, an implementation of SSH PF, an IPv4/IPv6 stateful firewall with NAT, PAT, QoS and traffic normalization support pfsync, a firewall state synchronization protocol for PF with high availability support using CARP sndio, a compact audio and MIDI framework spamd, a spam filter with greylisting support designed to inter-operate with PF Xenocara, a customized X.Org build infrastructure Some subsystems have been integrated into other BSD operating systems, and many are available as packages for use in other Unix-like systems. Linux administrator Carlos Fenollosa commented on moving from Linux to OpenBSD that the system is faithful to the Unix philosophy of small, simple tools that work together well: "Some base components are not as feature-rich, on purpose. Since 99% of the servers don't need the flexibility of Apache, OpenBSD's httpd will work fine, be more secure, and probably faster". He characterized the developer community's attitude to components as: "When the community decides that some module sucks, they develop a new one from scratch. OpenBSD has its own NTPd, SMTPd and, more recently, HTTPd. They work great". As a result, OpenBSD is relatively prolific in creating components that become widely reused by other systems. OpenBSD runs nearly all of its standard daemons within chroot and privsep security structures by default, as part of hardening the base system. The Calgary Internet Exchange was formed in 2012, in part to serve the needs of the OpenBSD project. Third-party components OpenBSD includes a number of third-party components, many with OpenBSD-specific patches, such as X.Org, Clang (the default compiler on several architectures), GCC, Perl, NSD, Unbound, ncurses, GNU binutils, GDB, and AWK. Development Development is continuous, and team management is open and tiered. Anyone with appropriate skills may contribute, with commit rights being awarded on merit and De Raadt acting as coordinator. Two official releases are made per year, with the version number incremented by 0.1, and these are each supported for twelve months (two release cycles). Snapshot releases are also available at frequent intervals. Maintenance patches for supported releases may be applied using syspatch, manually or by updating the system against the patch branch of the CVS source repository for that release. Alternatively, a system administrator may opt to upgrade to the next snapshot release using sysupgrade, or by using using the branch of the CVS repository, in order to gain pre-release access to recently added features. The sysupgrade tool can also upgrade to the latest stable release version. The generic OpenBSD kernel provided by default is strongly recommended for end users, in contrast to operating systems that recommend user kernel customization. Packages outside the base system are maintained by CVS through a ports tree and are the responsibility of the individual maintainers, known as porters. As well as keeping the current branch up to date, porters are expected to apply appropriate bug-fixes and maintenance fixes to branches of their package for OpenBSD's supported releases. Ports are generally not subject to the same continuous auditing as the base system due to lack of manpower. Binary packages are built centrally from the ports tree for each architecture. This process is applied for the current version, for each supported release, and for each snapshot. Administrators are recommended to use the package mechanism rather than build the package from the ports tree, unless they need to perform their own source changes. OpenBSD's developers regularly meet at special events called hackathons, where they "sit down and code", emphasizing productivity. Most new releases include a song. Open source and open documentation OpenBSD is known for its high-quality documentation. When OpenBSD was created, De Raadt decided that the source code should be available for anyone to read. At the time, a small team of developers generally had access to a project's source code. Chuck Cranor and De Raadt concluded this practice was "counter to the open source philosophy" and inconvenient to potential contributors. Together, Cranor and De Raadt set up the first public, anonymous revision control system server. De Raadt's decision allowed users to "take a more active role", and established the project's commitment to open access. OpenBSD is notable for its continued use of CVS (more precisely an unreleased, OpenBSD-managed fork named OpenCVS), when most other projects that used it have migrated to other systems. OpenBSD does not include closed source binary drivers in the source tree, nor do they include code requiring the signing of non-disclosure agreements. Since OpenBSD is based in Canada, no United States export restrictions on cryptography apply, allowing the distribution to make full use of modern algorithms for encryption. For example, the swap space is divided into small sections and each section is encrypted with its own key, ensuring that sensitive data does not leak into an insecure part of the system. OpenBSD randomizes various behaviors of applications, making them less predictable and thus more difficult to attack. For example, PIDs are created and associated randomly to processes; the bind system call uses random port numbers; files are created with random inode numbers; and IP datagrams have random identifiers. This approach also helps expose bugs in the kernel and in user space programs. The OpenBSD policy on openness extends to hardware documentation: in the slides for a December 2006 presentation, De Raadt explained that without it "developers often make mistakes writing drivers", and pointed out that "the [oh my god, I got it to work] rush is harder to achieve, and some developers just give up." He went on to say that vendor-supplied binary drivers are unacceptable for inclusion in OpenBSD, that they have "no trust of vendor binaries running in our kernel" and that there is "no way to fix [them] ... when they break." Licensing OpenBSD maintains a strict license policy, preferring the ISC license and other variants of the BSD license. The project attempts to "maintain the spirit of the original Berkeley Unix copyrights," which permitted a "relatively un-encumbered Unix source distribution." The widely used Apache License and GNU General Public License are considered overly restrictive. In June 2001, triggered by concerns over Darren Reed's modification of IPFilter's license wording, a systematic license audit of the OpenBSD ports and source trees was undertaken. Code in more than a hundred files throughout the system was found to be unlicensed, ambiguously licensed or in use against the terms of the license. To ensure that all licenses were properly adhered to, an attempt was made to contact all the relevant copyright holders: some pieces of code were removed, many were replaced, and others, such as the multicast routing tools and , were relicensed so that OpenBSD could continue to use them. Also removed during this audit was all software produced by Daniel J. Bernstein. At the time, Bernstein requested that all modified versions of his code be approved by him prior to redistribution, a requirement to which OpenBSD developers were unwilling to devote time or effort. Because of licensing concerns, the OpenBSD team has reimplemented software from scratch or adopted suitable existing software. For example, OpenBSD developers created the PF packet filter after unacceptable restrictions were imposed on IPFilter. PF first appeared in OpenBSD 3.0 and is now available in many other operating systems. OpenBSD developers have also replaced GPL-licensed tools (such as CVS, diff, grep and pkg-config) with permissively licensed equivalents. Funding Although the operating system and its portable components are used in commercial products, De Raadt says that little of the funding for the project comes from the industry: "traditionally all our funding has come from user donations and users buying our CDs (our other products don't really make us much money). Obviously, that has not been a lot of money." For a two-year period in the early 2000s, the project received funding from DARPA, which "paid the salaries of 5 people to work completely full-time, bought about $30k in hardware, and paid for 3 hackathons", from the POSSE project. In 2006, the OpenBSD project experienced financial difficulties. The Mozilla Foundation and GoDaddy are among the organizations that helped OpenBSD to survive. However, De Raadt expressed concern about the asymmetry of funding: "I think that contributions should have come first from the vendors, secondly from the corporate users, and thirdly from individual users. But the response has been almost entirely the opposite, with almost a 15-to-1 dollar ratio in favor of the little people. Thanks a lot, little people!" On 14 January 2014, Bob Beck issued a request for funding to cover electrical costs. If sustainable funding was not found, Beck suggested the OpenBSD project would shut down. The project soon received a US$20,000 donation from Mircea Popescu, the Romanian creator of the MPEx bitcoin stock exchange, paid in bitcoins. The project raised US$150,000 in response to the appeal, enabling it to pay its bills and securing its short-term future. OpenBSD Foundation The OpenBSD Foundation is a Canadian federal non-profit organization founded by the OpenBSD project as a "single point of contact for persons and organizations requiring a legal entity to deal with when they wish to support OpenBSD." It was announced to the public by OpenBSD developer Bob Beck on 25 July 2007. It also serves as a legal safeguard over other projects which are affiliated with OpenBSD, including OpenSSH, OpenBGPD, OpenNTPD, OpenCVS, OpenSMTPD and LibreSSL. Since 2014, several large contributions to the OpenBSD Foundation have come from corporations such as Microsoft, Facebook, and Google as well as the Core Infrastructure Initiative. In 2015, Microsoft became the foundation's first gold level contributor donating between $25,000-50,000 to support development of OpenSSH, which had been integrated into PowerShell in July, and later into Windows Server in 2018. Other contributors include Google, Facebook and DuckDuckGo. During the 2016 and 2017 fundraising campaigns, Smartisan, a Chinese company, was the leading financial contributor to the OpenBSD Foundation. Distribution OpenBSD is freely available in various ways: the source can be retrieved by anonymous CVS, and binary releases and development snapshots can be downloaded by FTP, HTTP, and rsync. Prepackaged CD-ROM sets through version 6.0 can be ordered online for a small fee, complete with an assortment of stickers and a copy of the release's theme song. These, with their artwork and other bonuses, have been one of the project's few sources of income, funding hardware, Internet service, and other expenses. Beginning with version 6.1, CD-ROM sets are no longer released. OpenBSD provides a package management system for easy installation and management of programs which are not part of the base operating system. Packages are binary files which are extracted, managed and removed using the package tools. On OpenBSD, the source of packages is the ports system, a collection of Makefiles and other infrastructure required to create packages. In OpenBSD, the ports and base operating system are developed and released together for each version: this means that the ports or packages released with, for example, 4.6 are not suitable for use with 4.5 and vice versa. Songs and artwork Initially, OpenBSD used a haloed version of the BSD daemon mascot drawn by Erick Green, who was asked by De Raadt to create the logo for the 2.3 and 2.4 versions of OpenBSD. Green planned to create a full daemon, including head and body, but only the head was completed in time for OpenBSD 2.3. The body as well as pitchfork and tail was completed for OpenBSD 2.4. Subsequent releases used variations such as a police daemon by Ty Semaka, but eventually settled on a pufferfish named Puffy. Since then, Puffy has appeared on OpenBSD promotional material and featured in release songs and artwork. The promotional material of early OpenBSD releases did not have a cohesive theme or design, but later the CD-ROMs, release songs, posters and tee-shirts for each release have been produced with a single style and theme, sometimes contributed to by Ty Semaka of the Plaid Tongued Devils. These have become a part of OpenBSD advocacy, with each release expounding a moral or political point important to the project, often through parody. Themes have included Puff the Barbarian in OpenBSD 3.3, which included an 80s rock song and parody of Conan the Barbarian alluding to open documentation, The Wizard of OS in OpenBSD 3.7, related to the project's work on wireless drivers, and Hackers of the Lost RAID, a parody of Indiana Jones referencing the new RAID tools in OpenBSD 3.8. Releases The following table summarizes the version history of the OpenBSD operating system. See also Comparison of BSD operating systems Comparison of open-source operating systems KAME project, responsible for OpenBSD's IPv6 support OpenBSD Journal OpenBSD security features Security-focused operating system Unix security Notes References External links GitHub mirror OpenBSD manual pages OpenBSD ports & packages (latest) OpenBSD source code search OpenBSD Cryptographic software Free software programmed in C Lightweight Unix-like systems OpenBSD software using the ISC license PowerPC operating systems Software forks Software using the BSD license 1996 software ARM operating systems IA-32 operating systems X86-64 operating systems Foundation Foundation

Operating System (OS)

AmigaOS 4 AmigaOS 4 (abbreviated as OS4 or AOS4) is a line of Amiga operating systems which runs on PowerPC microprocessors. It is mainly based on AmigaOS 3.1 source code developed by Commodore, and partially on version 3.9 developed by Haage & Partner. "The Final Update" (for OS version 4.0) was released on 24 December 2006 (originally released in April 2004) after five years of development by the Belgian company Hyperion Entertainment under license from Amiga, Inc. for AmigaOne registered users. History During the five years of development, purchasers of AmigaOne machines could download pre-release versions of AmigaOS 4.0 from Hyperion's repository as long as these were made available. On 20 December 2006, Amiga, Inc. terminated the contract with Hyperion Entertainment to produce or sell AmigaOS 4. Nevertheless, AmigaOS 4.0 was released commercially for Amigas with PowerUP accelerator cards in November 2007 (having been available only to developers and beta-testers until then). The Italian computer company ACube Systems has announced Sam440ep and Sam440ep-flex motherboards, which are AmigaOS 4 compatible. Also, a third party bootloader, known as the "Moana", was released by Acube on torrent sites; it allows installation of the Sam440ep version of OS4 to Mac Mini G4s. However this is both unofficial and unsupported as of today, and very incomplete, especially regarding drivers. During the judicial procedure (between Hyperion and Amiga, Inc.), OS4 was still being developed and distributed. On 30 September 2009, Hyperion Entertainment and Amiga, Inc. reached a settlement agreement where Hyperion is granted an exclusive right to AmigaOS 3.1 and market AmigaOS 4 and subsequent versions of AmigaOS (including AmigaOS 5 without limitation). Hyperion has assured the Amiga community that it will continue the development and the distribution of AmigaOS 4.x (and beyond), as it has done since November 2001. Description AmigaOS 4 can be divided into two parts: the Workbench and the Kickstart. Workbench The Workbench is the GUI of OS4, a graphical interface file manager and application launcher for the Operating System. It also includes some general purpose tools and utility programs such as a Notepad for typing text, MultiView for viewing images and Amigaguide documents, Unarc for unpacking Archives, a PDF reader, a number of small preferences programs for changing settings of the GUI and OS, among other programs. Kickstart The Kickstart contains many of the core components of the OS. Prior to version 4 of AmigaOS the Kickstart had been released mostly on a ROM (hardware included with the computer). In OS4 the Kickstart is instead stored on the hard disk. It consists mainly of: ExecSG, a preemptive multitasking kernel. ExecSG was licensed to Hyperion Entertainment by Thomas and Hans-Jörg Frieden. Intuition, a windowing system API. AmigaDOS and AmigaShell: AmigaDOS is the disk operating system for the OS, whereas AmigaShell is the integrated Command Line Interface (CLI). The CLI and the GUI complement each other and share the same privileges. Petunia, a Motorola 68020 processor emulator with dynamic recompilation, also called just-in-time compilation (JIT compilation), for PowerPC based Amigas. It gives OS4 backward compatibility to some extent, it will only run system friendly (following the OS3.x API without communicating directly with the classic Amigas' custom chipset) AmigaOS 3.x programs. For the programs that Petunia is unable to handle, such as most "bang the hardware" (using legacy Amiga hardware directly) Amiga games and Amiga demos, UAE can be used which can emulate different Amiga chipsets (OCS, ECS, AGA) as well. Development process There have been many different versions of the AmigaOS operating system (OS) during its three decades of history. Versions 1.0 to 1.3 The first AmigaOS was introduced in 1985 and developed by Commodore International. It was nicknamed Workbench from the name of its Graphical user interface (GUI), due to an error of Commodore Marketing and Sales Department, which labeled the OS disk just with the name "Workbench Disk" and not with the correct name "AmigaOS Disk (Workbench)". The first versions of AmigaOS (1.0 and up to 1.3) are here indicated with the name of their original disks to preserve original custom. Versions 2.0 to 3.1 Workbench 2.0 improvements introduced a lot of major advances to the GUI of Amiga operating system. The blue and orange colour scheme was replaced with a grey and light blue with 3D aspect in the border of the windows. The Workbench was no longer tied to the 640×256 (PAL) or 640×200 (NTSC) display modes, and much of the system was improved with an eye to making future expansion easier. For the first time, a standardised "look and feel" was added. This was done by creating the Amiga Style Guide, and including libraries and software which assisted developers in making conformant software. Technologies included the GUI element creation library gadtools, the software installation scripting language Installer, and the AmigaGuide hypertext help system. Versions 3.5 and 3.9 After the demise of Commodore International, the later owners of the Amiga trademark granted a license to a German company called Haage & Partner to update the Amiga's operating system. Along with this update came a change in the way people referred to the Amiga's operating system. Rather than specifying "Kickstart" or "Workbench", the updates were most often referred to as simply "AmigaOS". Whereas all previous OS releases ran on vanilla Amiga 500 with 68000 and 512 kB RAM, release 3.5 onwards required a 68020 or better and at least 4 MB fast RAM. Versions 4.0 and 4.1 In 2001 Amiga Inc. signed a contract with Hyperion Entertainment to develop the PowerPC native AmigaOS 4 from their previous AmigaOS 3.1 release. Unlike the previous versions which were based on the Motorola 68k central processor, OS4 runs only on PowerPC computer systems. Amiga, Inc.'s (current Amiga trademark owners) distribution policies for AmigaOS 4.0 and any later versions required that OS4 must be bundled with all new third-party hardware "Amigas", with the sole exception of Amigas with Phase5 PowerPC accelerator boards, for which OS4 is sold separately. This requirement was overturned in the agreement reached between Amiga, Inc. and Hyperion in the settlement of a lawsuit over the ownership of AmigaOS 4. In 2014 Hyperion introduced AmigaOS 4.1 Final Edition incorporating all previous downloadable updates and some new features like unified graphics library with RTG support and support for more than 2 GB RAM. Versions 4.2 In May 2012 Hyperion announced that they were working on AmigaOS 4.2. It would introduce hardware accelerated 3D support, multi-core support, a vastly improved file system API and many other features. AmigaOS 4 prominent features Prominent features compared to other operating systems or previous versions of AmigaOS: Appearance Screens: Users can have as many different screens as they like for any purpose, each with its own application on it; or they can open a public screen which several applications can share. Switching between screens can be done in an instant, and they can come back to an application and find it exactly how they left it. It is even possible to drag the current screen down to reveal another screen behind it (even if they have different display resolutions), so that they can view two screens simultaneously, or even drag and drop files and other content from one screen to another. Menuing: The menu bar appears at the top of the screen when the right mouse button is pressed down and disappears when it is not needed, thus reducing screen clutter and giving more room to work. File handling Descriptive file structure: Operating system files are divided up into clearly labelled drawers (folders). For example, all libraries are stored in "Libs:" standard virtual device and absolute path finder for "Libs" directory, Fonts are all in "Fonts:" absolute locator, the files for language localization are all stored in "Locale:" and so on. RAM disk: A virtual hard drive, it acts like any other disk, and stores files and data in memory rather than on the hard drive. The RAM disk is dynamically resizable and takes up only as much memory as it needs to. It can be used as a temporary store for the user's own purposes or as a place for software installers to put temporary files, and is cleared out at reboot so the hard drive will not be cluttered with thousands of unnecessary files that bog down your system. Additionally there is an optional RAD disk, a recoverable version of the RAM disk, which preserves contents after a reboot. Datatypes: Recognises and handles file types: displaying a picture, playing a music file, decoding a video file, rendering a web page etc. Any application can access Datatypes transparently, and thus have the ability to use any file that it has a Datatype for. Icon handling: A file can have a default icon representing the type of file or a custom icon specific to the individual file. Additionally icons can store extra commands and metadata about the associated file – which program to open it in, for example. Assigning devices: Instead of assigning drives (devices) a letter or fixed label, each drive can be given a name. Drives can be given more than one name so the system always knows where things are. If it is the system boot drive it is also known as "Sys:". Areas of hard drive can be assigned a label as if they were a virtual disk. For example, it is possible to mount MP3 players as "MP3:" and external networked resources as logical devices. Other Live CD: The OS4 installation CD can be used as a Live CD. Dockies: A fully configurable docking bar for icons, allowing quick access to most used applications. These dock bar icons, "Dockies", are fully dynamic, which means they can show real-time content and act as useful micro tools. A Docky might act as a magnifying glass, display the time, or show you the latest weather forecast or stock market information direct from the Internet. Scripting: Implemented scripting as a fundamental feature. Using the AREXX scripting language and Python it is possible to automate, integrate and remote control almost every application and function of the computer. Function sets and tools from several applications can be brought together into a single, integrated interface to allow the most complex jobs to be performed with the utmost simplicity. The Grim Reaper: The "Guru Meditation" is replaced by "The Grim Reaper", a crash handling system that attempts to catch crashes and attempts to stop them from getting out of control. It can provide complete information about the crash and optionally suspend the offending task. AmiUpdate: Is an updating system designed purely for the latest incarnation of the AmigaOS 4. It is able to update OS files and also all Amiga programs which are registered to use the same update program that is standard for Amiga. Updating AmigaOS requires only few libraries to be put in standard OS location "Libs:", "Fonts:" etc. This leaves Amiga users with a minimal knowledge of the system almost free to perform by hand the update of the system files. Compatible hardware Amiga Released for Amigas equipped with third party PPC add-on boards: Blizzard PPC equipped Amiga 1200 Blizzard 2604e (prototype card) equipped Amiga 2000 CyberStorm PPC equipped Amiga 3000 or Amiga 4000 AmigaOne Released for AmigaOne motherboards: AmigaOne-SE (A1-SE) AmigaOne-XE (A1-XE) Micro-AmigaOne (Micro-A1) AmigaOne X1000 (A1X1K; A1-X1000) AmigaOne 500 (A1-500), an AmigaOne computer based upon the Sam460ex board introduced by Acube Systems. AmigaOne X5000 (A1X5K; A1-X5000) Pegasos Released for Pegasos systems: Pegasos II (Peg2) Samantha Released for Sam440 systems: Sam440ep Sam440ep-flex Sam460ex Versions Future For the AmigaOS 4.2, Hyperion Entertainment planned the following updates: Multiple core support (SMP) New ExecSG scheduler Selectable policy for scheduling (may include per task) Scheduling of task groups with internal scheduling of tasks within that group Scheduling of tasks across multiple CPU cores (may include core affinity) Support for real-time scheduling Graphics and Gallium3D Enables access to full OpenGL implementations like Mesa Compositing may be done via Gallium3D Opens the door to replacing the entire graphics subsystem multi-header support See also Amiga AmigaOS AmigaOS versions AROS History of the Amiga Linux on Power MorphOS References Notes Review of Micro-AmigaOne and AmigaOS 4 Developer Prerelease Ars Technica reviews AmigaOS 4.0 Ars Technica reviews AmigaOS 4.1 A history of the Amiga, part 1 AmigaOS 4.0 - the fourth pre-release update External links 2006 software Amiga software AmigaOS 4 software Operating system distributions bootable from read-only media PowerPC operating systems

Operating System (OS)

Windows Vista Windows Vista is a major release of the Windows NT operating system developed by Microsoft. It was the direct successor to Windows XP, which was released five years prior, at the time being the longest time span between successive releases of Microsoft Windows desktop operating systems. Development was completed on November 8, 2006, and over the following three months, it was released in stages to computer hardware and software manufacturers, business customers and retail channels. On January 30, 2007, it was released internationally and was made available for purchase and download from the Windows Marketplace; it is the first release of Windows to be made available through a digital distribution platform. New features of Windows Vista include an updated graphical user interface and visual style dubbed Aero, a new search component called Windows Search, redesigned networking, audio, print and display sub-systems, and new multimedia tools such as Windows DVD Maker. Vista aimed to increase the level of communication between machines on a home network, using peer-to-peer technology to simplify sharing files and media between computers and devices. Windows Vista included version 3.0 of the .NET Framework, allowing software developers to write applications without traditional Windows APIs. While these new features and security improvements garnered positive reviews, Vista was also the target of much criticism and negative press. Criticism of Windows Vista includes its high system requirements, its more restrictive licensing terms, lack of compatibility, longer boot time, and excessive authorization prompts from User Account Control. As a result of these and other issues, Windows Vista saw initial adoption and satisfaction rates lower than Windows XP. However, Vista usage had surpassed Microsoft's pre-launch two-year-out expectations of achieving 200 million users, with an estimated 330 million Internet users in January 2009. On October 22, 2010, Microsoft ceased sales of retail copies of Windows Vista, and the original equipment manufacturer sales for Vista ceased a year later. Official mainstream support for Vista ended on April 10, 2012, and extended support ended on April 11, 2017, while Windows Server 2008 mainstream support ended on January 13, 2015, and extended support ended on January 14, 2020. Both versions were succeeded by Windows 7 and Windows Server 2008 R2, respectively. , Vista's market share has declined to 0.23% of Windows' total market share. The server equivalent received security updates until January 2020, which unofficial methods can apply these updates to the retail Windows Vista. Development Microsoft began work on Windows Vista, known at the time by its codename "Longhorn", in May 2001, five months before the release of Windows XP. It was originally expected to ship in late 2003 as a minor step between Windows XP and "Blackcomb", which was planned to be the company's next major operating system release. Gradually, "Longhorn" assimilated many of the important new features and technologies slated for Blackcomb, resulting in the release date being pushed back several times in three years. In some builds of Longhorn, their license agreement said "For the Microsoft product codenamed 'Whistler'". Many of Microsoft's developers were also re-tasked to build updates to Windows XP and Windows Server 2003 to strengthen security. Faced with ongoing delays and concerns about feature creep, Microsoft announced on August 27, 2004, that it had revised its plans. For this reason, Longhorn was reset to start work on componentizing the Windows Server 2003 Service Pack 1 codebase, and over time re-incorporating the features that would be intended for an actual operating system release. However, some previously announced features such as WinFS were dropped or postponed, and a new software development methodology called the Security Development Lifecycle was incorporated to address concerns with the security of the Windows codebase, which is programmed in C, C++ and assembly. Longhorn became known as Vista in 2005. Longhorn The early development stages of Longhorn were generally characterized by incremental improvements and updates to Windows XP. During this period, Microsoft was fairly quiet about what was being worked on, as their marketing and public relations efforts were more strongly focused on Windows XP, and Windows Server 2003, which was released in April 2003. Occasional builds of Longhorn were leaked onto popular file sharing networks such as IRC, BitTorrent, eDonkey and various newsgroups, and so most of what is known about builds before the first sanctioned development release of Longhorn in May 2003 is derived from these builds. After several months of relatively little news or activity from Microsoft with Longhorn, Microsoft released Build 4008, which had made an appearance on the Internet around February 28, 2003. It was also privately handed out to a select group of software developers. As an evolutionary release over build 3683, it contained several small improvements, including a modified blue "Plex" theme and a new, simplified Windows Image-based installer that operates in graphical mode from the outset, and completed an install of the operating system in approximately one third the time of Windows XP on the same hardware. An optional "new taskbar" was introduced that was thinner than the previous build and displayed the time differently. The most notable visual and functional difference, however, came with Windows Explorer. The incorporation of the Plex theme made blue the dominant color of the entire application. The Windows XP-style task pane was almost completely replaced with a large horizontal pane that appeared under the toolbars. A new search interface allowed for filtering of results, searching for Windows help, and natural-language queries that would be used to integrate with WinFS. The animated search characters were also removed. The "view modes" were also replaced with a single slider that would resize the icons in real-time, in the list, thumbnail, or details mode, depending on where the slider was. File metadata was also made more visible and more easily editable, with more active encouragement to fill out missing pieces of information. Also of note was the conversion of Windows Explorer to being a .NET application. Most builds of Longhorn and Vista were identified by a label that was always displayed in the bottom-right corner of the desktop. A typical build label would look like "Longhorn Build 3683.Lab06_N.020923-1821". Higher build numbers did not automatically mean that the latest features from every development team at Microsoft was included. Typically, a team working on a certain feature or subsystem would generate their working builds which developers would test with, and when the code was deemed stable, all the changes would be incorporated back into the main development tree at once. At Microsoft, several "Build labs" exist where the compilation of the entirety of Windows can be performed by a team. The name of the lab in which any given build originated is shown as part of the build label, and the date and time of the build follow that. Some builds (such as Beta 1 and Beta 2) only display the build label in the version information dialog (Winver). The icons used in these builds are from Windows XP. At the Windows Hardware Engineering Conference (WinHEC) in May 2003, Microsoft gave their first public demonstrations of the new Desktop Window Manager and Aero. The demonstrations were done on a revised build 4015 which was never released. Several sessions for developers and hardware engineers at the conference focused on these new features, as well as the Next-Generation Secure Computing Base (previously known as "Palladium"), which at the time was Microsoft's proposed solution for creating a secure computing environment whereby any given component of the system could be deemed "trusted". Also at this conference, Microsoft reiterated their roadmap for delivering Longhorn, pointing to an "early 2005" release date. Development reset By 2004, it had become obvious to the Windows team at Microsoft that they were losing sight of what needed to be done to complete the next version of Windows and ship it to customers. Internally, some Microsoft employees were describing the Longhorn project as "another Cairo" or "Cairo.NET", referring to the Cairo development project that the company embarked on through the first half of the 1990s, which never resulted in a shipping operating system (though nearly all the technologies developed in that time did end up in Windows 95 and Windows NT). Microsoft was shocked in 2005 by Apple's release of Mac OS X Tiger. It offered only a limited subset of features planned for Longhorn, in particular fast file searching and integrated graphics and sound processing, but appeared to have impressive reliability and performance compared to contemporary Longhorn builds. Most Longhorn builds had major Windows Explorer system leaks which prevented the OS from performing well, and added more confusion to the development teams in later builds with more and more code being developed which failed to reach stability. In a September 23, 2005 front-page article in The Wall Street Journal, Microsoft co-president Jim Allchin, who had overall responsibility for the development and delivery of Windows, explained how development of Longhorn had been "crashing into the ground" due in large part to the haphazard methods by which features were introduced and integrated into the core of the operating system, without a clear focus on an end-product. Allchin went on to explain how in December 2003, he enlisted the help of two other senior executives, Brian Valentine and Amitabh Srivastava, the former being experienced with shipping software at Microsoft, most notably Windows Server 2003, and the latter having spent his career at Microsoft researching and developing methods of producing high-quality testing systems. Srivastava employed a team of core architects to visually map out the entirety of the Windows operating system, and to proactively work towards a development process that would enforce high levels of code quality, reduce interdependencies between components, and in general, "not make things worse with Vista". Since Microsoft decided that Longhorn needed to be further componentized, work started on builds (known as the Omega-13 builds) that would componentize existing Windows Server 2003 source code, and over time add back functionality as development progressed. Future Longhorn builds would start from Windows Server 2003 Service Pack 1 and continue from there. This change, announced internally to Microsoft employees on August 26, 2004, began in earnest in September, though it would take several more months before the new development process and build methodology would be used by all of the development teams. A number of complaints came from individual developers, and Bill Gates himself, that the new development process was going to be prohibitively difficult to work within. As Windows Vista By approximately November 2004, the company had considered several names for the final release, ranging from simple to fanciful and inventive. In the end, Microsoft chose Windows Vista as confirmed on July 22, 2005, believing it to be a "wonderful intersection of what the product really does, what Windows stands for, and what resonates with customers, and their needs". Group Project Manager Greg Sullivan told Paul Thurrott "You want the PC to adapt to you and help you cut through the clutter to focus on what's important to you. That's what Windows Vista is all about: "bringing clarity to your world" (a reference to the three marketing points of Vista—Clear, Connected, Confident), so you can focus on what matters to you". Microsoft co-president Jim Allchin also loved the name, saying that "Vista creates the right imagery for the new product capabilities and inspires the imagination with all the possibilities of what can be done with Windows—making people's passions come alive." After Longhorn was named Windows Vista in July 2005, an unprecedented beta-test program was started, involving hundreds of thousands of volunteers and companies. In September of that year, Microsoft started releasing regular Community Technology Previews (CTP) to beta testers from July 2005 to February 2006. The first of these was distributed at the 2005 Microsoft Professional Developers Conference, and was subsequently released to beta testers and Microsoft Developer Network subscribers. The builds that followed incorporated most of the planned features for the final product, as well as a number of changes to the user interface, based largely on feedback from beta testers. Windows Vista was deemed feature-complete with the release of the "February CTP", released on February 22, 2006, and much of the remainder of the work between that build and the final release of the product focused on stability, performance, application and driver compatibility, and documentation. Beta 2, released in late May, was the first build to be made available to the general public through Microsoft's Customer Preview Program. It was downloaded over 5 million times. Two release candidates followed in September and October, both of which were made available to a large number of users. At the Intel Developer Forum on March 9, 2006, Microsoft announced a change in their plans to support EFI in Windows Vista. The UEFI 2.0 specification (which replaced EFI 1.10) was not completed until early 2006, and at the time of Microsoft's announcement, no firmware manufacturers had completed a production implementation which could be used for testing. As a result, the decision was made to postpone the introduction of UEFI support to Windows; support for UEFI on 64-bit platforms was postponed until Vista Service Pack 1 and Windows Server 2008 and 32-bit UEFI would not be supported, as Microsoft did not expect many such systems to be built because the market was quickly moving to 64-bit processors. While Microsoft had originally hoped to have the consumer versions of the operating system available worldwide in time for the 2006 holiday shopping season, it announced in March 2006 that the release date would be pushed back to January 2007 in order to give the company—and the hardware and software companies that Microsoft depends on for providing device drivers—additional time to prepare. Because a release to manufacturing (RTM) build is the final version of code shipped to retailers and other distributors, the purpose of a pre-RTM build is to eliminate any last "show-stopper" bugs that may prevent the code from responsibly being shipped to customers, as well as anything else that consumers may find annoying. Thus, it is unlikely that any major new features would be introduced; instead, work would focus on Vista's fit and finish. In just a few days, developers had managed to drop Vista's bug count from over 2470 on September 22 to just over 1400 by the time RC2 shipped in early October. However, they still had a way to go before Vista was ready to RTM. Microsoft's internal processes required Vista's bug count to drop to 500 or fewer before the product could go into escrow for RTM. For most of the pre-RTM builds, those 32-bit editions are only released. On June 14, 2006, Windows developer Philip Su posted a blog entry which decried the development process of Windows Vista, stating that "The code is way too complicated, and that the pace of coding has been tremendously slowed down by overbearing process." The same post also described Windows Vista as having approximately 50 million lines of code, with about 2,000 developers working on the product. During a demonstration of the speech recognition feature new to Windows Vista at Microsoft's Financial Analyst Meeting on July 27, 2006, the software recognized the phrase "Dear mom" as "Dear aunt". After several failed attempts to correct the error, the sentence eventually became "Dear aunt, let's set so double the killer delete select all". A developer with Vista's speech recognition team later explained that there was a bug with the build of Vista that was causing the microphone gain level to be set very high, resulting in the audio being received by the speech recognition software being "incredibly distorted". Windows Vista build 5824 (October 17, 2006) was supposed to be the RTM release, but a bug, which destroyed any system that was upgraded from Windows XP, prevented this, damaging development and lowering the chance that it would hit its January 2007 deadline. Development of Windows Vista came to an end when Microsoft announced that it had been finalized on November 8, 2006, and was concluded by co-president of Windows development, Jim Allchin. The RTM's build number had also jumped to 6000 to reflect Vista's internal version number, NT 6.0. Jumping RTM build numbers is common practice among consumer-oriented Windows versions, like Windows 98 (build 1998), Windows 98 SE (build 2222), Windows Me (build 3000) or Windows XP (build 2600), as compared to the business-oriented versions like Windows 2000 (build 2195) or Server 2003 (build 3790). On November 16, 2006, Microsoft made the final build available to MSDN and Technet Plus subscribers. A business-oriented Enterprise edition was made available to volume license customers on November 30, 2006. Windows Vista was launched for general customer availability on January 30, 2007. Two years after its release, Windows Vista was followed by Windows 7 in October 2009. New or changed features Windows Vista introduced several features and functionality not present in its predecessors. End-user Windows Aero: The new graphical user interface is named Windows Aero, which Jim Allchin stated is an acronym for Authentic, Energetic, Reflective, and Open. Microsoft intended the new interface to be cleaner and more aesthetically pleasing than those of previous Windows versions, featuring new transparencies, live thumbnails, live icons, and animations, thus providing a new level of eye candy. Laptop users report, however, that enabling Aero shortens battery life and reduces performance. Windows shell: The new Windows shell offers a new range of organization, navigation, and search capabilities: Task panes in Windows Explorer are removed, integrating the relevant task options into the toolbar. A "Favorite links" pane has been added, enabling one-click access to common directories. A search box appears in every Explorer window. The address bar has been replaced with a breadcrumb navigation bar. Icons of certain file types in Windows Explorer are "live" and can be scaled in size up to 256 × 256 pixels. The preview pane allows users to see thumbnails of various files and view the contents of documents. The details pane shows information such as file size and type, and allows viewing and editing of embedded tags in supported file formats. The Start menu has changed as well; incorporating an instant search box, and the All Programs list uses a horizontal scroll bar instead of the cascading flyout menu seen in Windows XP. The word "Start" itself has been removed in favor of a blue orb that bears the Windows logo. Windows Search: A new search component of Windows Vista, it features instant search (also known as search as you type), which provides instant search results, thus finding files more quickly than the search features found in previous versions of Windows and can search the contents of recognized file types. Users can search for certain metadata such as name, extension, size, date or attributes. Windows Sidebar: A transparent panel, anchored to the right side of the screen, wherein a user can place Desktop Gadgets, which are small applets designed for a specialized purpose (such as displaying the weather or sports scores). Gadgets can also be placed on the desktop. Windows Internet Explorer 7: New user interface, tabbed browsing, RSS, a search box, improved printing, Page Zoom, Quick Tabs (thumbnails of all open tabs), Anti-Phishing filter, several new security protection features, Internationalized Domain Name support (IDN), and improved web standards support. IE7 in Windows Vista runs in isolation from other applications in the operating system (protected mode); exploits and malicious software are restricted from writing to any location beyond Temporary Internet Files without explicit user consent. Windows Media Player 11, a major revamp of Microsoft's program for playing and organizing music and video. New features in this version include word wheeling (incremental search or "search as you type"), a new GUI for the media library, photo display and organization, the ability to share music libraries over a network with other Windows Vista machines, Xbox 360 integration, and support for other Media Center Extenders. Windows Defender: An antispyware program with several real-time protection agents. It includes a software explorer feature, which provides access to startup programs, and allows one to view currently running software, network-connected applications, and Winsock providers (Winsock LSPs). Backup and Restore Center: Includes a backup and restore application that gives users the ability to schedule periodic backups of files on their computer, as well as recovery from previous backups. Backups are incremental, storing only the changes made each time, minimizing disk usage. It also features Complete PC Backup (available only in the Ultimate, Business, and Enterprise editions), which backs up an entire computer as an image onto a hard disk or DVD. Complete PC Backup can automatically recreate a machine setup onto new hardware or hard disk in case of any hardware failures. Complete PC Restore can be initiated from within Windows Vista or from the Windows Vista installation CD if a PC is so corrupt that it cannot start normally from the hard disk. Windows Mail: A replacement for Outlook Express that includes a new mail store that improves stability, and features integrated instant search. It has a Phishing Filter like Internet Explorer 7 and Junk mail filtering that is enhanced through regular updates via Windows Update. Windows Calendar is a new calendar and task application that integrates with Windows Contacts and Windows Mail. It is compatible with various calendar file types, such as the popular iCalendar. Windows Photo Gallery, a photo and movie library management application. It can import from digital cameras, tag and rate individual items, adjust colors and exposure, create and display slideshows (with pan and fade effects) through Direct3D and burn slideshows to a DVD. Windows DVD Maker, a companion program to Windows Movie Maker that provides the ability to create video DVDs based on a user's content. Users can design a DVD with title, menus, video, soundtrack, pan and zoom motion effects on pictures or slides. Windows Media Center, which was previously exclusively bundled in a separate edition of Windows XP, known as Windows XP Media Center Edition, has been incorporated into the Home Premium and Ultimate editions of Windows Vista. Games: Most of the standard computer games included in previous versions of Windows have been redesigned to showcase Vista's new graphical capabilities. New games available in Windows Vista are Chess Titans (3D Chess game), Mahjong Titans (3D Mahjong game), and Purble Place (a small collection of games, oriented towards younger children, including a matching game, a cake-creator game, and a dress-up puzzle game). Purble Place is the only one of the new games available in the Windows Vista Home Basic edition. InkBall is available for Home Premium (or better) users. Games Explorer: A new special folder called "Games" exposes installed video games and information about them. These metadata may be updated from the Internet. Windows Mobility Center is a control panel that centralizes the most relevant information related to mobile computing (brightness, sound, battery level/power scheme selection, wireless network, screen orientation, presentation settings, etc.). Windows Fax and Scan Allows computers with fax modems to send and receive fax documents, as well as scan documents. It is not available in the Home editions of Windows Vista, but is available in the Business, Enterprise, and Ultimate editions. Windows Meeting Space replaces NetMeeting. Users can share applications (or their entire desktop) with other users on the local network, or over the Internet using peer-to-peer technology (higher editions than Starter and Home Basic can take advantage of hosting capabilities, Starter and Home Basic editions are limited to "join" mode only) Windows HotStart enables compatible computers to start applications directly from operating system startup or resume by the press of a button—this enables what Microsoft has described as appliance-like availability, which allows computers to function in a manner similar to a consumer electronics device such as a DVD player; the feature was also designed to provide the instant-on feature availability that is traditionally associated with mobile devices. While Microsoft has emphasized multimedia scenarios with Windows HotStart, a user can configure this feature so that a button launches a preferred application. Shadow Copy automatically creates daily backup copies of files and folders. Users can also create "shadow copies" by setting a System Protection Point using the System Protection tab in the System control panel. The user can view multiple versions of a file throughout a limited history and be allowed to restore, delete, or copy those versions. This feature is available only in the Business, Enterprise, and Ultimate editions of Windows Vista and is inherited from Windows Server 2003. Windows Update: Software and security updates have been simplified, now operating solely via a control panel instead of as a web application. Windows Mail's spam filter and Windows Defender's definitions are updated automatically via Windows Update. Users who choose the recommended setting for Automatic Updates will have the latest drivers installed and available when they add a new device. Parental controls: Allows administrators to monitor and restrict user activity, as well as control which websites, programs, and games each Standard user can use and install. This feature is not included in the Business or Enterprise editions of Vista. Windows SideShow: Enables the auxiliary displays on newer laptops or supported Windows Mobile devices. It is meant to be used to display device gadgets while the computer is on or off. Speech recognition is integrated into Vista. It features a redesigned user interface and configurable command-and-control commands. Unlike the Office 2003 version, which works only in Office and WordPad, Speech Recognition in Windows Vista works for any accessible application. In addition, it currently supports several languages: British and American English, Spanish, French, German, Chinese (Traditional and Simplified), and Japanese. New fonts, including several designed for screen reading, and improved Chinese (Yahei, JhengHei), Japanese (Meiryo), and Korean (Mulgan) fonts. ClearType has also been enhanced and enabled by default. Improved audio controls allow the system-wide volume or volume of individual audio devices and even individual applications to be controlled separately. New audio functionalities such as room correction, bass management, speaker fill, and headphone virtualization have also been incorporated. Problem Reports and Solutions, a feature that allows users to check for solutions to problems or view previously sent problems for any solutions or additional information, if available.Windows System Assessment Tool is a tool used to benchmark system performance. Software such as games can retrieve this rating and modify its own behavior at runtime to improve performance. The benchmark tests CPU, RAM, 2-D and 3-D graphics acceleration, graphics memory and hard disk space. Windows Ultimate Extras: The Ultimate edition of Windows Vista provides, via Windows Update, access to some additional features. These are a collection of additional MUI language packs, Texas Hold 'Em (a Poker game) and Microsoft Tinker (a strategy game where the character is a robot), BitLocker and EFS enhancements that allow users to back up their encryption key online in a Digital Locker, and Windows Dreamscene, which enables the use of videos in MPEG and WMV formats as the desktop background. On April 21, 2008, Microsoft launched two more Ultimate Extras; three new Windows sound schemes, and a content pack for Dreamscene. Various DreamScene Content Packs have been released since the final version of DreamScene was released. Reliability and Performance Monitor includes various tools for tuning and monitoring system performance and resources activities of CPU, disks, network, memory and other resources. It shows the operations on files, the opened connections, etc. Disk Management: The Logical Disk Manager in Windows Vista supports shrinking and expanding volumes on-the-fly. Windows Anytime Upgrade: is a program that allows a user to upgrade their computer running Vista to a higher edition. For example, a computer running Windows Vista Home Basic can be upgraded to Home Premium or better. Anytime Upgrade permits users to upgrade without having their programs and data erased, and is cheaper than replacing the existing installation of Windows. Anytime Upgrade is no longer available for Vista. Digital Locker Assistant: A program that facilitated access to downloads and purchases from the Windows Marketplace distribution platform. Apps purchased from Windows Marketplace are managed by Microsoft Account credentials, which are used to access a user's digital locker that stores the app and its associated information (e.g., licenses) off-site. Core Vista includes technologies such as ReadyBoost and ReadyDrive, which employ fast flash memory (located on USB flash drives and hybrid hard disk drives) to improve system performance by caching commonly used programs and data. This manifests itself in improved battery life on notebook computers as well, since a hybrid drive can be spun down when not in use. Another new technology called SuperFetch utilizes machine learning techniques to analyze usage patterns to allow Windows Vista to make intelligent decisions about what content should be present in system memory at any given time. It uses almost all the extra RAM as disk cache. In conjunction with SuperFetch, an automatic built-in Windows Disk Defragmenter makes sure that those applications are strategically positioned on the hard disk where they can be loaded into memory very quickly with the least physical movement of the hard disk's read-write heads. As part of the redesign of the networking architecture, IPv6 has been fully incorporated into the operating system and a number of performance improvements have been introduced, such as TCP window scaling. Earlier versions of Windows typically needed third-party wireless networking software to work properly, but this is not the case with Vista, which includes more comprehensive wireless networking support. For graphics, Vista introduces a new Windows Display Driver Model and a major revision to Direct3D. The new driver model facilitates the new Desktop Window Manager, which provides the tearing-free desktop and special effects that are the cornerstones of Windows Aero. Direct3D 10, developed in conjunction with major graphics card manufacturers, is a new architecture with more advanced shader support, and allows the graphics processing unit to render more complex scenes without assistance from the CPU. It features improved load balancing between CPU and GPU and also optimizes data transfer between them. WDDM also provides video content playback that rivals typical consumer electronics devices. It does this by making it easy to connect to external monitors, providing for protected HD video playback, and increasing overall video playback quality. For the first time in Windows, graphics processing unit (GPU) multitasking is possible, enabling users to run more than one GPU-intensive application simultaneously. At the core of the operating system, many improvements have been made to the memory manager, process scheduler and I/O scheduler. The Heap Manager implements additional features such as integrity checking in order to improve robustness and defend against buffer overflow security exploits, although this comes at the price of breaking backward compatibility with some legacy applications. A Kernel Transaction Manager has been implemented that enables applications to work with the file system and Registry using atomic transaction operations. Security-related Improved security was a primary design goal for Vista. Microsoft's Trustworthy Computing initiative, which aims to improve public trust in its products, has had a direct effect on its development. This effort has resulted in a number of new security and safety features and an Evaluation Assurance Level rating of 4+. User Account Control, or UAC is perhaps the most significant and visible of these changes. UAC is a security technology that makes it possible for users to use their computer with fewer privileges by default, to stop malware from making unauthorized changes to the system. This was often difficult in previous versions of Windows, as the previous "limited" user accounts proved too restrictive and incompatible with a large proportion of application software, and even prevented some basic operations such as looking at the calendar from the notification tray. In Windows Vista, when an action is performed that requires administrative rights (such as installing/uninstalling software or making system-wide configuration changes), the user is first prompted for an administrator name and password; in cases where the user is already an administrator, the user is still prompted to confirm the pending privileged action. Regular use of the computer such as running programs, printing, or surfing the Internet does not trigger UAC prompts. User Account Control asks for credentials in a Secure Desktop mode, in which the entire screen is dimmed, and only the authorization window is active and highlighted. The intent is to stop a malicious program from misleading the user by interfering with the authorization window, and to hint to the user about the importance of the prompt. Testing by Symantec Corporation has proven the effectiveness of UAC. Symantec used over 2,000 active malware samples, consisting of backdoors, keyloggers, rootkits, mass mailers, trojan horses, spyware, adware, and various other samples. Each was executed on a default Windows Vista installation within a standard user account. UAC effectively blocked over 50 percent of each threat, excluding rootkits. 5 percent or less of the malware that evaded UAC survived a reboot. Internet Explorer 7's new security and safety features include a phishing filter, IDN with anti-spoofing capabilities, and integration with system-wide parental controls. For added security, ActiveX controls are disabled by default. Also, Internet Explorer operates in a protected mode, which operates with lower permissions than the user and runs in isolation from other applications in the operating system, preventing it from accessing or modifying anything besides the Temporary Internet Files directory. Microsoft's anti-spyware product, Windows Defender, has been incorporated into Windows, protecting against malware and other threats. Changes to various system configuration settings (such as new auto-starting applications) are blocked unless the user gives consent. Whereas prior releases of Windows supported per-file encryption using Encrypting File System, the Enterprise and Ultimate editions of Vista include BitLocker Drive Encryption, which can protect entire volumes, notably the operating system volume. However, BitLocker requires approximately a 1.5-gigabyte partition to be permanently not encrypted and to contain system files for Windows to boot. In normal circumstances, the only time this partition is accessed is when the computer is booting, or when there is a Windows update that changes files in this area, which is a legitimate reason to access this section of the drive. The area can be a potential security issue, because a hexadecimal editor (such as dskprobe.exe), or malicious software running with administrator and/or kernel level privileges would be able to write to this "Ghost Partition" and allow a piece of malicious software to compromise the system, or disable the encryption. BitLocker can work in conjunction with a Trusted Platform Module (TPM) cryptoprocessor (version 1.2) embedded in a computer's motherboard, or with a USB key. However, as with other full disk encryption technologies, BitLocker is vulnerable to a cold boot attack, especially where TPM is used as a key protector without a boot PIN being required too. A variety of other privilege-restriction techniques are also built into Vista. An example is the concept of "integrity levels" in user processes, whereby a process with a lower integrity level cannot interact with processes of a higher integrity level and cannot perform DLL–injection to processes of a higher integrity level. The security restrictions of Windows services are more fine-grained, so that services (especially those listening on the network) cannot interact with parts of the operating system they do not need to. Obfuscation techniques such as address space layout randomization are used to increase the amount of effort required of malware before successful infiltration of a system. Code integrity verifies that system binaries have not been tampered with by malicious code. As part of the redesign of the network stack, Windows Firewall has been upgraded, with new support for filtering both incoming and outgoing traffic. Advanced packet filter rules can be created that can grant or deny communications to specific services. The 64-bit versions of Vista require that all device drivers be digitally signed, so that the creator of the driver can be identified. System management While much of the focus of Vista's new capabilities highlighted the new user interface, security technologies, and improvements to the core operating system, Microsoft also adding new deployment and maintenance features: The Windows Imaging Format (WIM) provides the cornerstone of Microsoft's new deployment and packaging system. WIM files, which contain a HAL-independent image of Windows Vista, can be maintained and patched without having to rebuild new images. Windows Images can be delivered via Systems Management Server or Business Desktop Deployment technologies. Images can be customized and configured with applications then deployed to corporate client personal computers using little to no touch by a system administrator. ImageX is the Microsoft tool used to create and customize images. Windows Deployment Services replaces Remote Installation Services for deploying Vista and prior versions of Windows. Approximately 700 new Group Policy settings have been added, covering most aspects of the new features in the operating system, as well as significantly expanding the configurability of wireless networks, removable storage devices, and user desktop experience. Vista also introduced an XML-based format (ADMX) to display registry-based policy settings, making it easier to manage networks that span geographic locations and different languages. Services for UNIX, renamed as "Subsystem for UNIX-based Applications", comes with the Enterprise and Ultimate editions of Vista. Network File System (NFS) client support is also included. Multilingual User Interface–Unlike previous versions of Windows (which required the loading of language packs to provide local-language support), Windows Vista Ultimate and Enterprise editions support the ability to dynamically change languages based on the logged-on user's preference. Wireless Projector support Developer Windows Vista includes a large number of new application programming interfaces. Chief among them is the inclusion of version 3.0 of the .NET Framework, which consists of a class library and Common Language Runtime. Version 3.0 includes four new major components: Windows Presentation Foundation is a user interface subsystem and framework based vector graphics, which makes use of 3D computer graphics hardware and Direct3D technologies. It provides the foundation for building applications and blending application UI, documents, and media content. It is the successor to Windows Forms. Windows Communication Foundation is a service-oriented messaging subsystem that enables applications and systems to interoperate locally or remotely using Web services. Windows Workflow Foundation provides task automation and integrated transactions using workflows. It is the programming model, engine, and tools for building workflow-enabled applications on Windows. Windows CardSpace is a component that securely stores digital identities of a person, and provides a unified interface for choosing the identity for a particular transaction, such as logging into a website. These technologies are also available for Windows XP and Windows Server 2003 to facilitate their introduction to and usage by developers and end-users. There are also significant new development APIs in the core of the operating system, notably the completely re-designed audio, networking, print, and video interfaces, major changes to the security infrastructure, improvements to the deployment and installation of applications ("ClickOnce" and Windows Installer 4.0), new device driver development model ("Windows Driver Foundation"), Transactional NTFS, mobile computing API advancements (power management, Tablet PC Ink support, SideShow) and major updates to (or complete replacements of) many core subsystems such as Winlogon and CAPI. There are some issues for software developers using some of the graphics APIs in Vista. Games or programs built solely on the Windows Vista-exclusive version of DirectX, version 10, cannot work on prior versions of Windows, as DirectX 10 is not available for previous Windows versions. Also, games that require the features of D3D9Ex, the updated implementation of DirectX 9 in Windows Vista are also incompatible with previous Windows versions. According to a Microsoft blog, there are three choices for OpenGL implementation on Vista. An application can use the default implementation, which translates OpenGL calls into the Direct3D API and is frozen at OpenGL version 1.4, or an application can use an Installable Client Driver (ICD), which comes in two flavors: legacy and Vista-compatible. A legacy ICD disables the Desktop Window Manager, a Vista-compatible ICD takes advantage of a new API, and is fully compatible with the Desktop Window Manager. At least two primary vendors, ATI and NVIDIA provided full Vista-compatible ICDs. However, hardware overlay is not supported, because it is considered as an obsolete feature in Vista. ATI and NVIDIA strongly recommend using compositing desktop/Framebuffer Objects for same functionality. Installation Windows Vista is the first Microsoft operating system: To use DVD-ROM media for installation That can be installed only on a partition formatted with the NTFS file system That provides support for loading drivers for SCSI, SATA and RAID controllers from any source in addition to floppy disks prior to its installation That can be installed on and booted from systems with GPT disks and UEFI firmware Unification of OEM and retail installation Windows Vista unifies the previously separate OEM and retail distributions of Microsoft Windows; a license for the edition purchased determines which version of Windows Vista is eligible for installation, regardless of its originating source. OEM and retail versions of Windows before Windows Vista were maintained separately on optical media—users with a manufacturer-supplied disc could not use a retail license during installation, and users with a retail disc could not use an OEM license during installation. Removed features Some notable Windows XP features and components have been replaced or removed in Windows Vista, including several shell and Windows Explorer features, multimedia features, networking related functionality, Windows Messenger, NTBackup, the network Windows Messenger service, HyperTerminal, MSN Explorer, Active Desktop, and the replacement of NetMeeting with Windows Meeting Space. Windows Vista also does not include the Windows XP "Luna" visual theme, or most of the classic color schemes that have been part of Windows since the Windows 3.x era. The "Hardware profiles" startup feature has also been removed, along with support for older motherboard technologies like the EISA bus, APM and game port support (though on the 32-bit version game port support can be enabled by applying an older driver). IP over FireWire (TCP/IP over IEEE 1394) has been removed as well. The IPX/SPX protocol has also been removed, although it can be enabled by a third-party plug-in. Support lifecycle Support for the original release of Windows Vista (without a service pack) ended on April 13, 2010. Windows XP SP2 was retired on July 13, 2010, and Service Pack 1 reached end of support on July 12, 2011, over three years after its general availability. Support for Windows XP, a predecessor of Windows Vista, ended on April 8, 2014, over 12 years after its launch. Mainstream support for Windows Vista officially ended on April 10, 2012. The "Extended Support" phase would last for the next 5 years, until April 11, 2017. Microsoft is no longer offering no-charge incident support, warranty claims, or design fixes for the operating system. For IT pros or users who needed to make specific fixes to the commercial Windows code, Microsoft required an extended hotfix agreement, which provided an additional 90 days from April 10, 2012. As part of the Extended Support phase, Vista users were still able to get security updates, and could still pay for support per incident, per-hour, or in other ways. Microsoft also made Windows Vista product information available through its online Knowledge Base. On April 11, 2017, Microsoft required Windows Vista users to upgrade to Windows 7 in order to continue receiving Microsoft Support. Editions Windows Vista shipped in six different editions. These are roughly divided into two target markets, consumer and business, with editions varying to cater to specific sub-markets. For consumers, there are three editions, with two available for economically more developed countries. Windows Vista Starter edition is aimed at low-powered computers with availability only in emerging markets. Windows Vista Home Basic is intended for budget users. Windows Vista Home Premium covers the majority of the consumer market and contains applications for creating and using multimedia. The home editions cannot join a Windows Server domain. For businesses, there are three editions as well. Windows Vista Business is specifically designed for small and medium-sized enterprises, while Windows Vista Enterprise is only available to customers participating in Microsoft's Software Assurance program. Windows Vista Ultimate contains the complete feature-set of both the Home and Business (combination of both Home Premium and Enterprise) editions, as well as a set of Windows Ultimate Extras, and is aimed at enthusiasts. All editions except Windows Vista Starter support both 32-bit (x86) and 64-bit (x64) processor architectures. In the European Union, Home Basic N and Business N variants are also available. These come without Windows Media Player, due to EU sanctions brought against Microsoft for violating anti-trust laws. Similar sanctions exist in South Korea. Visual styles Windows Vista has four distinct visual styles. Windows Aero Vista's default visual style, Windows Aero, is built on a desktop composition engine called Desktop Window Manager. Windows Aero introduces support for translucency effects (Glass), window thumbnails on the taskbar, window animations, and other visual effects (for example Windows Flip 3D), and is intended for mainstream and high-end video cards. To enable these features, the contents of every open window are stored in video memory to facilitate tearing-free movement of windows. As such, Windows Aero has significantly higher hardware requirements than its predecessors: systems running Vista must have video card drivers compatible with the Windows Display Driver Model (WDDM), and the minimum graphics memory required is 128 MB, depending on the resolution used.Windows Aero is not included in the Starter and Home Basic editions. A variant of Windows Aero, dubbed Windows Vista Standard, lacking the glass effects, window animations, and other advanced graphical effects, is included in Home Basic. Windows Vista Basic This visual style does not employ the Desktop Window Manager; as such, it does not feature transparency or translucency, window animation, Windows Flip 3D or any of the functions provided by the DWM. It is the default visual style on Windows Vista Starter and on systems without WDDM-compatible display drivers, and has similar video card requirements to Windows XP. Before Service Pack 1, a machine that failed Windows Genuine Advantage validation would also default to this visual style. Windows Standard The Windows Standard and Windows Classic visual styles reprise the user interface of Windows 9x, Windows 2000 and Microsoft's Windows Server line of operating systems. As with previous versions of Windows, this visual style supports custom color schemes, which are collections of color settings. Windows Vista includes four high-contrast color schemes and the default color schemes from Windows 98 (titled "Windows Classic") and Windows 2000/Windows Me (titled "Windows Standard"). Hardware requirements Computers capable of running Windows Vista are classified as Vista Capable and Vista Premium Ready. A Vista Capable or equivalent PC is capable of running all editions of Windows Vista although some of the special features and high-end graphics options may require additional or more advanced hardware. A Vista Premium Ready PC can take advantage of Vista's high-end features. Windows Vista's Basic and Classic interfaces work with virtually any graphics hardware that supports Windows XP or 2000; accordingly, most discussion around Vista's graphics requirements centers on those for the Windows Aero interface. As of Windows Vista Beta 2, the NVIDIA GeForce 6 series and later, the ATI Radeon 9500 and later, Intel's GMA 950 and later integrated graphics, and a handful of VIA chipsets and S3 Graphics discrete chips are supported. Although originally supported, the GeForce FX 5 series has been dropped from newer drivers from NVIDIA. The last driver from NVIDIA to support the GeForce FX series on Vista was 96.85. Microsoft offered a tool called the Windows Vista Upgrade Advisor to assist Windows XP and Vista users in determining what versions of Windows their machine is capable of running. The required server connections for this utility are no longer available. Although the installation media included in retail packages is a 32-bit DVD, customers needing a CD-ROM or customers who wish for a 64-bit install media can acquire this media through the Windows Vista Alternate Media program. The Ultimate edition includes both 32-bit and 64-bit media. The digitally downloaded version of Ultimate includes only one version, either 32-bit or 64-bit, from Windows Marketplace. Physical memory limits The maximum amount of RAM that Windows Vista can support varies, depending on both its edition and its processor architecture, as shown in the table. Processor limits The maximum number of logical processors in a PC that Windows Vista supports is: 32 for 32-bit; 64 for 64-bit. The maximum number of physical processors in a PC that Windows Vista supports is: 2 for Business, Enterprise, and Ultimate, and 1 for Starter, Home Basic, and Home Premium. Updates Microsoft occasionally releases updates such as service packs for its Windows operating systems to fix bugs, improve performance and add new features. Service Pack 1 Windows Vista Service Pack 1 (SP1) was released on February 4, 2008, alongside Windows Server 2008 to OEM partners, after a five-month beta test period. The initial deployment of the service pack caused a number of machines to continually reboot, rendering the machines unusable. This temporarily caused Microsoft to suspend automatic deployment of the service pack until the problem was resolved. The synchronized release date of the two operating systems reflected the merging of the workstation and server kernels back into a single code base for the first time since Windows 2000. MSDN subscribers were able to download SP1 on February 15, 2008. SP1 became available to current Windows Vista users on Windows Update and the Download Center on March 18, 2008. Initially, the service pack only supported five languages – English, French, Spanish, German and Japanese. Support for the remaining 31 languages was released on April 14, 2008. A white paper, published by Microsoft on August 29, 2007, outlined the scope and intent of the service pack, identifying three major areas of improvement: reliability and performance, administration experience, and support for newer hardware and standards. One area of particular note is performance. Areas of improvement include file copy operations, hibernation, logging off on domain-joined machines, JavaScript parsing in Internet Explorer, network file share browsing, Windows Explorer ZIP file handling, and Windows Disk Defragmenter. The ability to choose individual drives to defragment is being reintroduced as well. Service Pack 1 introduced support for some new hardware and software standards, notably the exFAT file system, 802.11n wireless networking, IPv6 over VPN connections, and the Secure Socket Tunneling Protocol. Booting a system using Extensible Firmware Interface on x64 systems was also introduced; this feature had originally been slated for the initial release of Vista but was delayed due to a lack of compatible hardware at the time. Booting from a GUID Partition Table–based hard drive greater than 2.19 TB is supported (x64 only). Two areas have seen changes in SP1 that have come as the result of concerns from software vendors. One of these is desktop search; users will be able to change the default desktop search program to one provided by a third party instead of the Microsoft desktop search program that comes with Windows Vista, and desktop search programs will be able to seamlessly tie in their services into the operating system. These changes come in part due to complaints from Google, whose Google Desktop Search application was hindered by the presence of Vista's built-in desktop search. In June 2007, Google claimed that the changes being introduced for SP1 "are a step in the right direction, but they should be improved further to give consumers greater access to alternate desktop search providers". The other area of note is a set of new security APIs being introduced for the benefit of antivirus software that currently relies on the unsupported practice of patching the kernel (see Kernel Patch Protection). An update to DirectX 10, named DirectX 10.1, marked mandatory several features that were previously optional in Direct3D 10 hardware. Graphics cards will be required to support DirectX 10.1. SP1 includes a kernel (6001.18000) that matches the version shipped with Windows Server 2008. The Group Policy Management Console (GPMC) was replaced by the Group Policy Object Editor. An updated downloadable version of the Group Policy Management Console was released soon after the service pack. SP1 enables support for hotpatching, a reboot-reduction servicing technology designed to maximize uptime. It works by allowing Windows components to be updated (or "patched") while they are still in use by a running process. Hotpatch-enabled update packages are installed via the same methods as traditional update packages, and will not trigger a system reboot. Service Pack 2 Service Pack 2 for Windows Vista was released to manufacturing on April 28, 2009, and released to Microsoft Download Center and Windows Update on May 26, 2009, one year after the release of Windows Vista SP1, and five months before the release of Windows 7. In addition to a number of security and other fixes, a number of new features have been added. However, it did not include Internet Explorer 8, but instead was included in Windows 7, which was released five months after Vista SP2. Windows Search 4 (available for SP1 systems as a standalone update) Feature Pack for Wireless adds support for Bluetooth 2.1 Windows Feature Pack for Storage enables the data recording onto Blu-ray media Windows Connect Now (WCN) to simplify Wi-Fi configuration Improved support for resuming with active Wi-Fi connections Improved support for eSATA drives The limit of 10 half-open, outgoing TCP connections introduced in Windows XP SP2 was removed Enables the exFAT file system to support UTC timestamps, which allows correct file synchronization across time zones Support for ICCD/CCID smart cards Support for VIA 64-bit CPUs Improved performance and responsiveness with the RSS feeds sidebar Improves audio and video performance for streaming high-definition content Improves Windows Media Center (WMC) in content protection for TV Provides an improved power management policy that is approximately 10% more efficient than the original with the default policies Windows Vista and Windows Server 2008 share a single service pack binary, reflecting the fact that their code bases were joined with the release of Server 2008. Service Pack 2 is not a cumulative update meaning that Service Pack 1 must be installed first. Platform Update The Platform Update for Windows Vista was released on October 27, 2009. It includes major new components that shipped with Windows 7, as well as updated runtime libraries. It requires Service Pack 2 of Windows Vista or Windows Server 2008 and is listed on Windows Update as a Recommended download. The Platform Update allows application developers to target both Windows Vista and Windows 7. It consists of the following components: Windows Graphics runtime: Direct2D, DirectWrite, Direct3D 11, DXGI 1.1, and WARP Updates to Windows Imaging Component Updates to XPS Print API, XPS Document API and XPS Rasterization Service Windows Automation API (updates to MSAA and UI Automation) Windows Portable Devices Platform (adds support for MTP over Bluetooth and MTP Device Services) Windows Ribbon API Windows Animation Manager library Some updates are available as separate releases for both Windows XP and Windows Vista: Windows Management Framework: Windows PowerShell 2.0, Windows Remote Management 2.0, BITS 4.0 Remote Desktop Connection 7.0 (RDP7) client Although extensive, the Platform Update does not bring Windows Vista to the level of features and performance offered by Windows 7. For example, even though Direct3D 11 runtime will be able to run on D3D9-class hardware and WDDM drivers using "feature levels" first introduced in Direct3D 10.1, Desktop Window Manager has not been updated to use Direct3D 10.1. In July 2011, Microsoft released the Platform Update Supplement for Windows Vista and Windows Server 2008, which contains several bug fixes and performance improvements. Out-of-band patches BlueKeep patch Microsoft has released an update for Windows Vista SP2 to resolve the BlueKeep security vulnerability (), which affects the Remote Desktop Protocol in older Windows versions. Subsequent related flaws, (collectively known as DejaBlue) do not affect Windows Vista or earlier versions of Windows. The installation of this patch changed the build number of Windows Vista from 6002 to 6003. Unofficial out-of-band patches While Windows Vista support ended on April 11, 2017 support could be unofficially extended by installing Windows Server 2008 updates, this allowed Windows Vista users to install security updates until the Windows Server 2008 end of support date of January 14, 2020. Below are out-of-band updates that were released for Windows Server 2008 and newer but can be installed on Windows Vista. Text Services Framework patch The Text Services Framework was compromised by a privilege escalation vulnerability () that could allow attackers to use the framework to perform privileged operations, run software, or send messages to privileged processes from unprivileged processes—bypassing security features such as sandboxes or User Account Control. Microsoft remediated issues related to this vulnerability with the release of a patch in August 2019 for Windows Vista SP2, Windows Server 2008 SP2, and later versions of Windows. Malware Protection Engine patch A vulnerability related to Windows Defender that affected the way the Malware Protection Engine operates () was reported in May 2017. If Windows Defender scanned a specially crafted file, it would lead to memory corruption, potentially allowing an attacker to control the affected machine or perform arbitrary code execution in the context of LocalSystem; the vulnerability was exacerbated by the default real-time protection settings of Windows Defender, which were configured to automatically initiate malware scans at regular intervals. The first version of the Protection Engine affected by the vulnerability is Version 1.1.13701.0—subsequent versions of the engine are unaffected. Microsoft released a patch to address the issue. Termination of update services Windows Vista support ended on April 11, 2017, and no more updates were released for the OS apart from the rare out-of-band patches. Windows Update Services for the OS continued to work to install previously released updates up until July 2020 when SHA-1 Windows Update endpoints were discontinued. However, as of May 2021, the Microsoft Update Catalog is still hosting these updates for download for Windows Vista. Marketing campaign The Mojave Experiment In July 2008, Microsoft introduced a web-based advertising campaign called the "Mojave Experiment", which depicts a group of people who are asked to evaluate the newest operating system from Microsoft, calling it Windows 'Mojave'. Participants are first asked about Vista, if they have used it, and their overall satisfaction with Vista on a scale of 1 to 10. They are then shown a demo of some of the new operating system's features, and asked their opinion and satisfaction with it on the same 1 to 10 scale. After respondents rate "Mojave", they are then told that they were shown a demo of Windows Vista. The object was to test "A theory: If people could see Windows Vista firsthand, they would like it." According to Microsoft, the initial sample of respondents rated Vista an average of 4.4 out of 10, and Mojave received an average of 8.5, with no respondents rating Mojave lower than they originally rated Windows Vista before the demo. The "experiment" has been criticized for deliberate selection of positive statements and not addressing all aspects of Vista. During the launch of Vista, Microsoft also made a lime flavored sparkling water available to campus visitors and developers. Reception Windows Vista received mixed to negative reviews at the time of its release and throughout its lifespan, mainly for its much higher hardware requirements and perceived slowness compared to Windows XP. It received generally positive reviews from PC gamers who praised the advantages brought by DirectX 10, which allowed for better gaming performance and more realistic graphics, as well as support for many new capabilities featured in new GPUs. However, many DirectX 9 games initially ran with lower frame rates compared to when they were run on Windows XP. In mid-2008, benchmarks suggested that the SP1 update improved performance to be on par with (or better than) Windows XP in terms of game performance. Peter Bright of Ars Technica wrote that, despite its delays and feature cuts, Windows Vista is "a huge evolution in the history of the NT platform [...] The fundamental changes to the platform are of a scale not seen since the release of NT [3.1; the first version]." In a continuation of his previous assessment, Bright stated that "Vista is not simply XP with a new skin; core parts of the OS have been radically overhauled, and virtually every area has seen significant refinement. In terms of the magnitude and extent of these changes, Vista represents probably the biggest leap that the NT platform has ever seen. Never before have significant subsystems been gutted and replaced in the way they are in Vista." Many others in the tech industry echoed these sentiments at the time, directing praise towards the massive amount of technical features new to Windows Vista. Windows Vista received the "Best of CES" award at the Consumer Electronics Show in 2007. In its first year of availability, PC World rated it as the biggest tech disappointment of 2007, and it was rated by InfoWorld as No. 2 of Tech's all-time 25 flops. Microsoft's then much smaller competitor Apple noted that, despite Vista's far greater sales, its own operating system did not seem to have suffered after its release, and would later invest in advertising mocking Vista's unpopularity with users. Computer manufacturers such as Dell, Lenovo, and Hewlett-Packard released their newest computers with Windows Vista pre-installed; however, after the negative reception of the operating system, they also began selling their computers with Windows XP CDs included because of a drop in sales. Sales A Gartner research report predicted that Vista business adoption in 2008 would overtake that of XP during the same time frame (21.3% vs. 16.9%) while IDC had indicated that the launch of Windows Server 2008 served as a catalyst for the stronger adoption rates. As of January 2009, Forrester Research had indicated that almost one third of North American and European corporations had started deploying Vista. At a May 2009 conference, a Microsoft Vice President said "Adoption and deployment of Windows Vista has been slightly ahead of where we had been with XP" for big businesses. Within its first month, 20 million copies of Vista were sold, double the amount of Windows XP sales within its first month in October 2001, five years earlier. Shortly after however, due to Vista's relatively low adoption rates and continued demand for Windows XP, Microsoft decided to sell Windows XP until June 30, 2008, instead of the previously planned date of January 31, 2008. There were reports of Vista users "downgrading" their operating systems back to XP, as well as reports of businesses planning to skip Vista. A study conducted by ChangeWave in March 2008 showed that the percentage of corporate users who were "very satisfied" with Vista was dramatically lower than other operating systems, with Vista at 8%, compared to the 40% who said they were "very satisfied" with Windows XP. The internet-usage market share for Windows Vista after two years of availability, in January 2009, was 20.61%. This figure combined with World Internet Users and Population Stats yielded a user base of roughly 330 million, which exceeded Microsoft's two-year post launch expectations by 130 million. The internet user base reached before the release of its successor (Windows 7) was roughly 400 million according to the same statistical sources. Criticism Windows Vista has received several negative assessments. Criticism targets include protracted development time (5–6 years), more restrictive licensing terms, the inclusion of several technologies aimed at restricting the copying of protected digital media, and the usability of the new User Account Control security technology. Moreover, some concerns have been raised about many PCs meeting "Vista Premium Ready" hardware requirements and Vista's pricing. Hardware requirements While in 2005 Microsoft claimed "nearly all PCs on the market today will run Windows Vista", the higher requirements of some of the "premium" features, such as the Aero interface, affected many upgraders. According to the UK newspaper The Times in May 2006, the full set of features "would be available to less than 5 percent of Britain's PC market"; however, this prediction was made several months before Vista was released. This continuing lack of clarity eventually led to a class action against Microsoft as people found themselves with new computers that were unable to use the new software to its full potential despite the assurance of "Vista Capable" designations. The court case has made public internal Microsoft communications that indicate that senior executives have also had difficulty with this issue. For example, Mike Nash (Corporate Vice President, Windows Product Management) commented, "I now have a $2,100 e-mail machine" because of his laptop's lack of an appropriate graphics chip so hobbled Vista. Licensing Criticism of upgrade licenses pertaining to Windows Vista Starter through Home Premium was expressed by Ars Technicas Ken Fisher, who noted that the new requirement of having a prior operating system already installed was going to irritate users who reinstall Windows regularly. It has been revealed that an Upgrade copy of Windows Vista can be installed clean without first installing a previous version of Windows. On the first install, Windows will refuse to activate. The user must then reinstall that same copy of Vista. Vista will then activate on the reinstall, thus allowing a user to install an Upgrade of Windows Vista without owning a previous operating system. As with Windows XP, separate rules still apply to OEM versions of Vista installed on new PCs: Microsoft asserts that these versions are not legally transferable (although whether this conflicts with the right of first sale has yet to be clearly decided legally). Cost Initially, the cost of Windows Vista was also a source of concern and commentary. A majority of users in a poll said that the prices of various Windows Vista editions posted on the Microsoft Canada website in August 2006 make the product too expensive. A BBC News report on the day of Vista's release suggested that, "there may be a backlash from consumers over its pricing plans—with the cost of Vista versions in the US roughly half the price of equivalent versions in the UK." Since the release of Vista in 2006, Microsoft has reduced the retail, and upgraded the price point of Vista. Originally, Vista Ultimate was priced at $399, and Home Premium Vista at $239. These prices have since been reduced to $319 and $199 respectively. Digital rights management Windows Vista supports additional forms of DRM restrictions. One aspect of this is the Protected Video Path, which is designed so that "premium content" from HD DVD or Blu-ray Discs may mandate that the connections between PC components be encrypted. Depending on what the content demands, the devices may not pass premium content over non-encrypted outputs, or they must artificially degrade the quality of the signal on such outputs or not display it at all. Drivers for such hardware must be approved by Microsoft; a revocation mechanism is also included, which allows Microsoft to disable drivers of devices in end-user PCs over the Internet. Peter Gutmann, security researcher and author of the open source cryptlib library, claims that these mechanisms violate fundamental rights of the user (such as fair use), unnecessarily increase the cost of hardware, and make systems less reliable (the "tilt bit" being a particular worry; if triggered, the entire graphic subsystem performs a reset) and vulnerable to denial-of-service attacks. However, despite several requests for evidence supporting such claims Peter Gutmann has never supported his claims with any researched evidence. Proponents have claimed that Microsoft had no choice but to follow the demands of the movie studios, and that the technology will not actually be enabled until after 2010; Microsoft also noted that content protection mechanisms have existed in Windows as far back as Windows ME, and that the new protections will not apply to any existing content, only future content. User Account Control Although User Account Control (UAC) is an important part of Vista's security infrastructure as it blocks software from silently gaining administrator privileges without the user's knowledge, it has been widely criticized for generating too many prompts. This has led many Vista UAC users to consider it troublesome, with some consequently either turning the feature off or (for Windows Vista Enterprise or Windows Vista Ultimate users) putting it in auto-approval mode. Responding to this criticism, Microsoft altered the implementation to reduce the number of prompts with SP1. Though the changes resulted in some improvement, it did not alleviate the concerns completely. Downgrade rights End-users of licenses of Windows 7 acquired through OEM or volume licensing may downgrade to the equivalent edition of Windows Vista. Downgrade rights are not offered for Starter, Home Basic or Home Premium editions of Windows 7. For Windows 8 licenses acquired through an OEM, a user may also downgrade to the equivalent edition of Windows Vista. Customers licensed for use of Windows 8 Enterprise are generally licensed for Windows 8 Pro, which may be downgraded to Windows Vista Business. See also BlueKeep (security vulnerability) Comparison of Windows Vista and Windows XP Microsoft Security Essentials Notes References External links Windows Vista End of Support Windows Vista Service Pack 2 (SP2) Update 2006 software IA-32 operating systems Products and services discontinued in 2017 Vista X86-64 operating systems

Operating System (OS)

Robot Operating System Robot Operating System (ROS or ros) is an open-source robotics middleware suite. Although ROS is not an operating system but a collection of software frameworks for robot software development, it provides services designed for a heterogeneous computer cluster such as hardware abstraction, low-level device control, implementation of commonly used functionality, message-passing between processes, and package management. Running sets of ROS-based processes are represented in a graph architecture where processing takes place in nodes that may receive, post and multiplex sensor data, control, state, planning, actuator, and other messages. Despite the importance of reactivity and low latency in robot control, ROS itself is not a real-time OS (RTOS). It is possible, however, to integrate ROS with real-time code. The lack of support for real-time systems has been addressed in the creation of ROS 2, a major revision of the ROS API which will take advantage of modern libraries and technologies for core ROS functionality and add support for real-time code and embedded hardware. Software in the ROS Ecosystem can be separated into three groups: language-and platform-independent tools used for building and distributing ROS-based software; ROS client library implementations such as , , and ; packages containing application-related code which uses one or more ROS client libraries. Both the language-independent tools and the main client libraries (C++, Python, and Lisp) are released under the terms of the BSD license, and as such are open-source software and free for both commercial and research use. The majority of other packages are licensed under a variety of open-source licenses. These other packages implement commonly used functionality and applications such as hardware drivers, robot models, datatypes, planning, perception, simultaneous localization and mapping, simulation tools, and other algorithms. The main ROS client libraries are geared toward a Unix-like system, primarily because of their dependence on large collections of open-source software dependencies. For these client libraries, Ubuntu Linux is listed as "Supported" while other variants such as Fedora Linux, macOS, and Microsoft Windows are designated "experimental" and are supported by the community. The native Java ROS client library, , however, does not share these limitations and has enabled ROS-based software to be written for the Android OS. has also enabled ROS to be integrated into an officially supported MATLAB toolbox which can be used on Linux, macOS, and Microsoft Windows. A JavaScript client library, has also been developed which enables integration of software into a ROS system via any standards-compliant web browser. History Early days at Stanford (2007 and earlier) Sometime before 2007, the first pieces of what eventually would become ROS were beginning to come together at Stanford University. Eric Berger and Keenan Wyrobek, PhD students working in Kenneth Salisbury's robotics laboratory at Stanford, were leading the Personal Robotics Program. While working on robots to do manipulation tasks in human environments, the two students noticed that many of their colleagues were held back by the diverse nature of robotics: an excellent software developer might not have the hardware knowledge required, someone developing state of the art path planning might not know how to do the computer vision required. In an attempt to remedy this situation, the two students set out to make a baseline system that would provide a starting place for others in academia to build upon. In the words of Eric Berger, "something that didn’t suck, in all of those different dimensions". In their first steps towards this unifying system, the two built the PR1 as a hardware prototype and began to work on software from it, borrowing the best practices from other early open-source robotic software frameworks, particularly switchyard, a system that Morgan Quigley, another Stanford PhD student, had been working on in support of the STAIR (STanford Artificial Intelligence Robot) by the Stanford Artificial Intelligence Laboratory. Early funding of US$50,000 was provided by Joanna Hoffman and Alain Rossmann, which supported the development of the PR1. While seeking funding for further development, Eric Berger and Keenan Wyrobek met Scott Hassan, the founder of Willow Garage, a technology incubator which was working on an autonomous SUV and a solar autonomous boat. Hassan shared Berger and Wyrobek's vision of a "Linux for robotics", and invited them to come and work at Willow Garage. Willow Garage was started in January 2007, and the first commit of ROS code was made to SourceForge on the seventh of November, 2007. Willow Garage (2007-2013) Willow Garage began developing the PR2 robot as a follow-up to the PR1, and ROS as the software to run it. Groups from more than twenty institutions made contributions to ROS, both the core software and the growing number of packages which worked with ROS to form a greater software ecosystem. The fact that people outside of Willow were contributing to ROS (particularly from Stanford's STAIR project) meant that ROS was a multi-robot platform from the beginning. While Willow Garage had originally had other projects in progress, they were scrapped in favor of the Personal Robotics Program: focused on producing the PR2 as a research platform for academia and ROS as the open-source robotics stack that would underlie both academic research and tech startups, much like the LAMP stack did for web-based startups. In December 2008, Willow Garage met the first of their three internal milestones: continuous navigation for the PR2 over a period of two days and a distance of pi kilometers. Soon after, an early version of ROS (0.4 Mango Tango) was released, followed by the first RVIZ documentation and the first paper on ROS. In early summer, the second internal milestone: having the PR2 navigate the office, open doors, and plug itself it in, was reached. This was followed in August by the initiation of the ROS.org website. Early tutorials on ROS were posted in December, preparing for the release of ROS 1.0, in January 2010. This was Milestone 3: producing tons of documentation and tutorials for the enormous capabilities that Willow Garage's engineers had developed over the preceding 3 years. Following this, Willow Garage achieved one of its longest held goals: giving away 10 PR2 robots to worthy academic institutions. This had long been a goal of the founders, as they felt that the PR2 could kick-start robotics research around the world. They ended up awarding eleven PR2s to different institutions, including University of Freiburg (Germany), Bosch, Georgia Tech, KU Leuven (Belgium), MIT, Stanford, TU Munich (Germany), UC Berkeley, U Penn, USC, and University of Tokyo (Japan). This, combined with Willow Garage's highly successful internship program (run from 2008 to 2010 by Melonee Wise), helped to spread the word about ROS throughout the robotics world. The first official ROS distribution release: ROS Box Turtle, was released on 2 March 2010, marking the first time that ROS was officially distributed with a set of versioned packages for public use. These developments led to the first drone running ROS, the first autonomous car running ROS, and the adaption of ROS for Lego Mindstorms. With the PR2 Beta program well underway, the PR2 robot was officially released for commercial purchase on 9 September 2010. 2011 was a banner year for ROS with the launch of ROS Answers, a Q/A forum for ROS users, on 15 February; the introduction of the highly successful TurtleBot robot kit on 18 April; and the total number of ROS repositories passing 100 on 5 May. Willow Garage began 2012 by creating the Open Source Robotics Foundation (OSRF) in April. The OSRF was immediately awarded a software contract by the Defense Advanced Research Projects Agency (DARPA). Later that year, the first ROSCon was held in St. Paul, Minnesota, the first book on ROS, ROS By Example, was published, and Baxter, the first commercial robot to run ROS, was announced by Rethink Robotics. Soon after passing its fifth anniversary in November, ROS began running on every continent on 3 December 2012. In February 2013, the OSRF became the primary software maintainers for ROS, foreshadowing the announcement in August that Willow Garage would be absorbed by its founders, Suitable Technologies. At this point, ROS had released seven major versions (up to ROS Groovy), and had users all over the globe. This chapter of ROS development would be finalized when Clearpath Robotics took over support responsibilities for the PR2 in early 2014. OSRF and Open Robotics (2013–present) In the years since OSRF took over primary development of ROS, a new version has been released every year, while interest in ROS continues to grow. ROSCons have occurred every year since 2012, co-located with either ICRA or IROS, two flagship robotics conferences. Meetups of ROS developers have been organized in a variety of countries, a number of ROS books have been published, and many educational programs initiated. On 1 September 2014, NASA announced the first robot to run ROS in space: Robotnaut 2, on the International Space Station. In 2017, the OSRF changed its name to Open Robotics. Tech giants Amazon and Microsoft began to take an interest in ROS during this time, with Microsoft porting core ROS to Windows in September 2018, followed by Amazon Web Services releasing RoboMaker in November 2018. Perhaps the most important development of the OSRF/Open Robotics years thus far (not to discount the explosion of robot platforms which began to support ROS or the enormous improvements in each ROS version) was the proposal of ROS 2, a significant API change to ROS which is intended to support real time programming, a wider variety of computing environments, and utilize more modern technology. ROS 2 was announced at ROSCon 2014, the first commits to the repository were made in February 2015, followed by alpha releases in August 2015. The first distribution release of ROS 2, Ardent Apalone, was released on 8 December 2017, ushering in a new era of next-generation ROS development. Design Philosophy ROS was designed with open source in mind, intending that users would be able to choose the configuration of tools and libraries which interacted with the core of ROS so that users could shift their software stacks to fit their robot and application area. As such, there is very little which is actually core to ROS, beyond the general structure within which programs must exist and communicate. In one sense, ROS is the underlying plumbing behind nodes and message passing. However, in reality, ROS is not only that plumbing, but a rich and mature set of tools, a wide-ranging set of robot-agnostic capabilities provided by packages, and a greater ecosystem of additions to ROS. Computation graph model ROS processes are represented as nodes in a graph structure, connected by edges called topics. ROS nodes can pass messages to one another through topics, make service calls to other nodes, provide a service for other nodes, or set or retrieve shared data from a communal database called the parameter server. A process called the ROS Master makes all of this possible by registering nodes to itself, setting up node-to-node communication for topics, and controlling parameter server updates. Messages and service calls do not pass through the master, rather the master sets up peer-to-peer communication between all node processes after they register themselves with the master. This decentralized architecture lends itself well to robots, which often consist of a subset of networked computer hardware, and may communicate with off-board computers for heavy computation or commands. Nodes A node represents a single process running the ROS graph. Every node has a name, which it registers with the ROS master before it can take any other actions. Multiple nodes with different names can exist under different namespaces, or a node can be defined as anonymous, in which case it will randomly generate an additional identifier to add to its given name. Nodes are at the center of ROS programming, as most ROS client code is in the form of a ROS node which takes actions based on information received from other nodes, sends information to other nodes, or sends and receives requests for actions to and from other nodes. Topics Topics are named buses over which nodes send and receive messages. Topic names must be unique within their namespace as well. To send messages to a topic, a node must publish to said topic, while to receive messages it must subscribe. The publish/subscribe model is anonymous: no node knows which nodes are sending or receiving on a topic, only that it is sending/receiving on that topic. The types of messages passed on a topic vary widely and can be user-defined. The content of these messages can be sensor data, motor control commands, state information, actuator commands, or anything else. Services A node may also advertise services. A service represents an action that a node can take which will have a single result. As such, services are often used for actions which have a defined beginning and end, such as capturing a single-frame image, rather than processing velocity commands to a wheel motor or odometer data from a wheel encoder. Nodes advertise services and call services from one another. Parameter server The parameter server is a database shared between nodes which allows for communal access to static or semi-static information. Data which does not change frequently and as such will be infrequently accessed, such as the distance between two fixed points in the environment, or the weight of the robot, are good candidates for storage in the parameter server. Tools ROS's core functionality is augmented by a variety of tools which allow developers to visualize and record data, easily navigate the ROS package structures, and create scripts automating complex configuration and setup processes. The addition of these tools greatly increases the capabilities of systems using ROS by simplifying and providing solutions to a number of common robotics development problems. These tools are provided in packages like any other algorithm, but rather than providing implementations of hardware drivers or algorithms for various robotic tasks, these packages provide task and robot-agnostic tools which come with the core of most modern ROS installations. is a three-dimensional visualizer used to visualize robots, the environments they work in, and sensor data. It is a highly configurable tool, with many different types of visualizations and plugins. is a command line tool used to record and playback ROS message data. uses a file format called bags, which log ROS messages by listening to topics and recording messages as they come in. Playing messages back from a bag is largely the same as having the original nodes which produced the data in the ROS computation graph, making bags a useful tool for recording data to be used in later development. While is a command line only tool, provides a GUI interface to . catkin catkin is the ROS build system, having replaced as of ROS Groovy. catkin is based on CMake, and is similarly cross-platform, open-source, and language-independent. The package provides a suite of tools which augment the functionality of the bash shell. These tools include , , and , which replicate the functionalities of ls, cd, and cp respectively. The ROS versions of these tools allow users to use package names in place of the file path where the package is located. The package also adds tab-completion to most ROS utilities, and includes rosed, which edits a given file with the chosen default text editor, as well , which runs executables in ROS packages. supports the same functionalities for zsh and tcsh, to a lesser extent. is a tool used to launch multiple ROS nodes both locally and remotely, as well as setting parameters on the ROS parameter server. configuration files, which are written using XML can easily automate a complex startup and configuration process into a single command. scripts can include other scripts, launch nodes on specific machines, and even restart processes which die during execution. Packages of note ROS contains many open-source implementations of common robotics functionality and algorithms. These open-source implementations are organized into packages. Many packages are included as part of ROS distributions, while others may be developed by individuals and distributed through code sharing sites such as . Some packages of note include: Systems and tools provides a standardized interface for interfacing with preemptable tasks. provides a way to run multiple algorithms in a single process. provides a JSON API to ROS functionalities for non-ROS programs. Mapping and localization slam toolbox provides full 2D SLAM and localization system. provides a wrapper for OpenSlam's Gmapping algorithm for simultaneous localization and mapping. cartographer provides real time 2D and 3D SLAM algorithms developed at Google. provides an implementation of adaptive Monte-Carlo localization. Navigation navigation provides the capability of navigating a mobile robot in a planar environment. Perception is a meta-package which provides packages for integrating ROS with OpenCV. Coordinate frame representation provided a system for representing, tracking and transforming coordinate frames until ROS Hydro, when it was deprecated in favor of . is the second generation of the library, and provides the same capabilities for ROS versions after Hydro. Simulation is a meta-package which provides packages for integrating ROS with the Gazebo simulator. stage provides an interface for the 2D Stage simulator. Versions and releases ROS releases may be incompatible with other releases and are often referred to by code name rather than version number. ROS currently releases a version every year in May, following the release of Ubuntu LTS versions. ROS 2 currently releases a new version every six months (in December and July). These releases are supported for a single year. There are currently two active major versions seeing releases: ROS 1 and ROS 2. Aside to this there is the ROS-Industrial or ROS-I derivate project since at least 2012. ROS 1 ROS 2 ROS-Industrial ROS-Industrial is an open-source project (BSD (legacy)/Apache 2.0 (preferred) license) that extends the advanced capabilities of ROS to manufacturing automation and robotics. In the industrial environment, there are two different approaches to programming a robot: either through an external proprietary controller, typically implemented using ROS, or via the respective native programming language of the robot. ROS can therefore be seen as the software-based approach to program industrial robots instead of the classic robot controller-based approach. The ROS-Industrial repository includes interfaces for common industrial manipulators, grippers, sensors, and device networks. It also provides software libraries for automatic 2D/3D sensor calibration, process path/motion planning, applications like Scan-N-Plan, developer tools like the Qt Creator ROS Plugin, and training curriculum that is specific to the needs of manufacturers. ROS-I is supported by an international Consortium of industry and research members. The project began as a collaborative endeavor between Yaskawa Motoman Robotics, Southwest Research Institute, and Willow Garage to support the use of ROS for manufacturing automation, with the GitHub repository being founded in January 2012 by Shaun Edwards (SwRI). Currently, the Consortium is divided into three groups; the ROS-Industrial Consortium Americas (led by SwRI and located in San Antonio, Texas), the ROS-Industrial Consortium Europe (led by Fraunhofer IPA and located in Stuttgart, Germany) and the ROS-Industrial Consortium Asia Pacific (led by Advanced Remanufacturing and Technology Centre (ARTC) and Nanyang Technological University (NTU) and located in Singapore). The Consortia supports the global ROS-Industrial community by conducting ROS-I training, providing technical support and setting the future roadmap for ROS-I, as well as conducting pre-competitive joint industry projects to develop new ROS-I capabilities. ROS-compatible robots and hardware Robots ABB, Adept, Fanuc, Motoman, and Universal Robots are supported by ROS-Industrial. Baxter at Rethink Robotics, Inc. CK-9: robotics development kit by Centauri Robotics, supports ROS. HERB developed at Carnegie Mellon University in Intel's personal robotics program Husky A200: robot developed (and integrated into ROS) by Clearpath Robotics PR1: personal robot developed in Ken Salisbury's lab at Stanford PR2: personal robot being developed at Willow Garage Raven II Surgical Robotic Research Platform Shadow Robot Hand: a fully dexterous humanoid hand. STAIR I and II: robots developed in Andrew Ng's lab at Stanford SummitXL: mobile robot developed by Robotnik, an engineering company specialized in mobile robots, robotic arms, and industrial solutions with ROS architecture. Nao humanoid: University of Freiburg's Humanoid Robots Lab developed a ROS integration for the Nao humanoid based on an initial port by Brown University UBR1: developed by Unbounded Robotics, a spin-off of Willow Garage. ROSbot: autonomous robot platform by Husarion Webots: robot simulator integrating a complete ROS programming interface. GoPiGo3: Raspberry Pi-based educational robot, supports ROS. SBCs and hardware BeagleBoard: the robotics lab of the Katholieke Universiteit Leuven, Belgium has ported ROS to the Beagleboard. Sitara ARM Processors have support for the ROS package as part of the official Linux SDK. Raspberry Pi: image of Ubuntu Mate with ROS by Ubiquity Robotics; installation guide for Raspbian. See also Open hardware Robotics middleware Open-source software List of free and open-source software packages References Notes STAIR: The STanford Artificial Intelligence Robot project, Andrew Y. Ng, Stephen Gould, Morgan Quigley, Ashutosh Saxena, Eric Berger. Snowbird, 2008. Related projects RT middleware – Robot middleware standard/implementations. RT-component is discussed/defined by the Object Management Group. External links 2007 in robotics 2007 software Computer vision software Free software operating systems Open-source robots Robot operating systems manipulation Robotics suites Software using the BSD license

Operating System (OS)

List of file systems The following lists identify, characterize, and link to more thorough information on Computer file systems. Many older operating systems support only their one "native" file system, which does not bear any name apart from the name of the operating system itself. Disk file systems Disk file systems are usually block-oriented. Files in a block-oriented file system are sequences of blocks, often featuring fully random-access read, write, and modify operations. ADFS – Acorn's Advanced Disc filing system, successor to DFS. AdvFS – Advanced File System, designed by Digital Equipment Corporation for their Digital UNIX (now Tru64 UNIX) operating system. APFS – Apple File System is a next-generation file system for Apple products. AthFS – AtheOS File System, a 64-bit journaled filesystem now used by Syllable. Also called AFS. BFS – the Boot File System used on System V release 4.0 and UnixWare. BFS – the Be File System used on BeOS, occasionally misnamed as BeFS. Open source implementation called OpenBFS is used by the Haiku operating system. Byte File System (BFS) - file system used by z/VM for Unix applications Btrfs – is a copy-on-write file system for Linux announced by Oracle in 2007 and published under the GNU General Public License (GPL). CFS – The Cluster File System from Veritas, a Symantec company. It is the parallel access version of VxFS. CP/M file system — Native filesystem used in the CP/M (Control Program for Microcomputers) operating system which was first released in 1974. DOS 3.x – Original floppy operating system and file system developed for the Apple II. Extent File System (EFS) – an older block filing system under IRIX. ext – Extended file system, designed for Linux systems. ext2 – Second extended file system, designed for Linux systems. ext3 – A journaled form of ext2. ext4 – A follow up for ext3 and also a journaled filesystem with support for extents. ext3cow – A versioning file system form of ext3. FAT – File Allocation Table, initially used on DOS and Microsoft Windows and now widely used for portable USB storage and some other devices; FAT12, FAT16 and FAT32 for 12-, 16- and 32-bit table depths. VFAT – Optional layer on Microsoft Windows FAT system to allow long (up to 255 character) filenames instead of only the 8.3 filenames allowed in the plain FAT filesystem. FATX – A modified version of Microsoft Windows FAT system that is used on the original Xbox console. FFS (Amiga) – Fast File System, used on Amiga systems. This FS has evolved over time. Now counts FFS1, FFS Intl, FFS DCache, FFS2. FFS – Fast File System, used on *BSD systems Fossil – Plan 9 from Bell Labs snapshot archival file system. Files-11 – OpenVMS file system; also used on some PDP-11 systems; supports record-oriented files Flex machine file system HAMMER — clustered DragonFly BSD filesystem, production-ready since DragonFly 2.2 (2009) HAMMER2 — recommended as the default root filesystem in DragonFly since 5.2 release in 2018 HFS – Hierarchical File System in IBM's z/OS; not to be confused with Apple's HFS. HFS is still supported but IBM's stated direction is zFS. HFS – Hierarchical File System, in use until HFS+ was introduced on Mac OS 8.1. Also known as Mac OS Standard format. Successor to Macintosh File System (MFS) & predecessor to HFS+; not to be confused with IBM's HFS provided with z/OS HFS+ – Updated version of Apple's HFS, Hierarchical File System, supported on Mac OS 8.1 & above, including macOS. Supports file system journaling, enabling recovery of data after a system crash. Also referred to as 'Mac OS Extended format or HFS Plus HPFS – High Performance File System, used on OS/2 HTFS – High Throughput Filesystem, used on SCO OpenServer ISO 9660 – Used on CD-ROM and DVD-ROM discs (Rock Ridge and Joliet are extensions to this) JFS – IBM Journaling file system, provided in Linux, OS/2, and AIX. Supports extents. LFS – 4.4BSD implementation of a log-structured file system MFS – Macintosh File System, used on early Classic Mac OS systems. Succeeded by Hierarchical File System (HFS). Next3 – A form of ext3 with snapshots support. MFS – TiVo's Media File System, a proprietary fault tolerant format used on TiVo hard drives for real time recording from live TV. Minix file system – Used on Minix systems NILFS – Linux implementation of a log-structured file system NTFS – (New Technology File System) Used on Microsoft's Windows NT-based operating systems NetWare File System – The original NetWare 2.x–5.x file system, used optionally by later versions. NSS – Novell Storage Services. This is a new 64-bit journaling file system using a balanced tree algorithm. Used in NetWare versions 5.0-up and recently ported to Linux. OneFS – One File System. This is a fully journaled, distributed file system used by Isilon. OneFS uses FlexProtect and Reed–Solomon encodings to support up to four simultaneous disk failures. OFS – Old File System, on Amiga. Good for floppies, but fairly useless on hard drives. OS-9 file system PFS – and PFS2, PFS3, etc. Technically interesting file system available for the Amiga, performs very well under a lot of circumstances. Very simple and elegant. ProDOS – Operating system and file system successor to DOS 3.x, for use on Apple's computers prior to the Macintosh & Lisa computers, the Apple series, including the IIgs Qnx4fs – File system that is used in QNX version 4 and 6. ReFS (Resilient File System) – New file system by Microsoft that is built on the foundations of NTFS (but cannot boot, has a default cluster size of 64 KB and does not support compression) and is intended to be used with the Windows Server 2012 operating system. ReiserFS – File system that uses journaling Reiser4 – File system that uses journaling, newest version of ReiserFS Reliance – Datalight's transactional file system for high reliability applications Reliance Nitro – Tree-based transactional file system developed for high-performance embedded systems, from Datalight RFS – Native filesystem for RTEMS SkyFS – Developed for SkyOS to replace BFS as the operating system's main file system. It is based on BFS, but contains many new features. SFS – Smart File System, journaling file system available for the Amiga platforms. Soup (Apple) – the "file system" for Apple Newton Platform, structured as a shallow database Tux3 – An experimental versioning file system intended as a replacement for ext3 UDF – Packet-based file system for WORM/RW media such as CD-RW and DVD, now supports hard drives and flash memory as well. UFS – Unix File System, used on Solaris and older BSD systems UFS2 – Unix File System, used on newer BSD systems VxFS Veritas file system, first commercial journaling file system; HP-UX, Solaris, Linux, AIX, UnixWare VTOC (Volume Table Of Contents) - Data structure on IBM mainframe direct-access storage devices (DASD) such as disk drives that provides a way of locating the data sets that reside on the DASD volume. XFS – Used on SGI IRIX and Linux systems zFS – z/OS File System; not to be confused with other file systems named zFS or ZFS. zFS - an IBM research project to develop a distributed, decentralized file system; not to be confused with other file systems named zFS or ZFS. ZFS a combined file system and logical volume manager designed by Sun Microsystems File systems with built-in fault-tolerance These file systems have built-in checksumming and either mirroring or parity for extra redundancy on one or several block devices: Bcachefs – It's not yet upstream, full data and metadata checksumming, bcache is the bottom half of the filesystem. Btrfs – A file system based on B-Trees, initially designed at Oracle Corporation. HAMMER and HAMMER2 – DragonFly BSD's primary filesystems, created by Matt Dillon. NOVA – The "non-volatile memory accelerated" file system for persistent main memory. ReFS (Resilient File System) – A file system by Microsoft with built-in resiliency features. Reliance – A transactional file system with CRCs, created by Datalight. Reliance Nitro – A tree-based transactional file system with CRCs, developed for high performance and reliability in embedded systems, from Datalight. WekaFS – a shared parallel filesystem that delivers extreme performance at any scale and is optimized for NVMe and the hybrid cloud. ZFS – Has checksums for all data; important metadata is always redundant, additional redundancy levels are user-configurable; copy-on-write and transactional writing ensure metadata consistency; corrupted data can be automatically repaired if a redundant copy is available. Created by Sun Microsystems for use on Solaris 10 and OpenSolaris, ported to FreeBSD 7.0, NetBSD (as of August 2009), Linux and to FUSE (not to be confused with the two zFSes from IBM) File systems optimized for flash memory, solid state media Solid state media, such as flash memory, are similar to disks in their interfaces, but have different problems. At low level, they require special handling such as wear leveling and different error detection and correction algorithms. Typically a device such as a solid-state drive handles such operations internally and therefore a regular file system can be used. However, for certain specialized installations (embedded systems, industrial applications) a file system optimized for plain flash memory is advantageous. APFS – Apple File System is a next-generation file system for Apple products. CHFS – a NetBSD filesystem for embedded systems optimised for raw flash media. exFAT – Microsoft proprietary system intended for flash cards (see also XCFiles, an exFAT implementation for Wind River VxWorks and other embedded operating systems). ExtremeFFS – internal filesystem for SSDs. F2FS – Flash-Friendly File System. An open source Linux file system introduced by Samsung in 2012. FFS2 (presumably preceded by FFS1), one of the earliest flash file systems. Developed and patented by Microsoft in the early 1990s. JFFS – original log structured Linux file system for NOR flash media. JFFS2 – successor of JFFS, for NAND and NOR flash. LSFS – a Log-structured file system with writable snapshots and inline data deduplication created by StarWind Software. Uses DRAM and flash to cache spinning disks. LogFS – intended to replace JFFS2, better scalability. No longer under active development. NILFS – a log-structured file system for Linux with continuous snapshots. Non-Volatile File System – the system for flash memory introduced by Palm, Inc. NOVA – the "non-volatile memory accelerated" file system for persistent main memory. OneFS – a filesystem utilized by Isilon. It supports selective placement of meta-data directly onto flash SSD. Segger Microcontroller Systems emFile – filesystem for deeply embedded applications which supports both NAND and NOR flash. Wear leveling, fast read and write, and very low RAM usage. SPIFFS – SPI Flash File System, a wear-leveling filesystem intended for small NOR flash devices. TFAT – a transactional version of the FAT filesystem. TrueFFS – internal file system for SSDs, implementing error correction, bad block re-mapping and wear-leveling. UBIFS – successor of JFFS2, optimized to utilize NAND and NOR flash. Write Anywhere File Layout (WAFL) – an internal file system utilized by NetApp within their DataONTAP OS, originally optimized to use non-volatile DRAM. WAFL uses RAID-DP to protect against multiple disk failures and NVRAM for transaction log replays. YAFFS – a log-structured file system designed for NAND flash, but also used with NOR flash. LittleFS – a little fail-safe filesystem designed for microcontrollers. JesFS – Jo's embedded serial FileSystem. A very small footprint and robust filesystem, designed for very small microcontroller (16/32 bit). Open Source and licensed under GPL v3. Record-oriented file systems In record-oriented file systems files are stored as a collection of records. They are typically associated with mainframe and minicomputer operating systems. Programs read and write whole records, rather than bytes or arbitrary byte ranges, and can seek to a record boundary but not within records. The more sophisticated record-oriented file systems have more in common with simple databases than with other file systems. CMS file system – The native file system of the Conversational Monitor System component of VM/370 Files-11 – early versions were record-oriented; support for "streams" was added later Michigan Terminal System (MTS) – provides "line files" where record lengths and line numbers are associated as metadata with each record in the file, lines can be added, replaced, updated with the same or different length records, and deleted anywhere in the file without the need to read and rewrite the entire file. OS4000 for GEC's OS4000 operating system, on the GEC 4000 series minicomputers A FAT12 and FAT16 (and FAT32) extension to support database-like file types random file, direct file, keyed file and sequential file in Digital Research FlexOS, IBM 4680 OS and Toshiba 4690 OS. The record size is stored on a file-by-file basis in special entries in the directory table. Sequential access methods for IBM's z/OS and z/VSE mainframe operating systems: Basic Sequential Access Method (BSAM), Basic Partitioned Access Method (BPAM) and Queued Sequential Access Method (QSAM); see Access methods and Data set (IBM mainframe) for more examples Pick Operating System – A record-oriented filesystem and database that uses hash-coding to store data. Shared File System (SFS) for IBM's VM Virtual Storage Access Method (VSAM) for IBM's z/OS and z/VSE mainframe operating systems Shared-disk file systems Shared-disk file systems (also called shared-storage file systems, SAN file system, Clustered file system or even cluster file systems) are primarily used in a storage area network where all nodes directly access the block storage where the file system is located. This makes it possible for nodes to fail without affecting access to the file system from the other nodes. Shared-disk file systems are normally used in a high-availability cluster together with storage on hardware RAID. Shared-disk file systems normally do not scale over 64 or 128 nodes. Shared-disk file systems may be symmetric where metadata is distributed among the nodes or asymmetric with centralized metadata servers. CXFS (Clustered XFS) from Silicon Graphics (SGI). Available for Linux, Mac, Windows, Solaris, AIX and IRIX,. Asymmetric. Dell Fluid File System (formerly ExaFS) proprietary software sold by Dell. Shared-disk system sold as an appliance providing distributed file systems to clients. Running on Intel based hardware serving NFS v2/v3, SMB/CIFS and AFP to Windows, macOS, Linux and other UNIX clients. Blue Whale Clustered file system (BWFS) from Zhongke Blue Whale. Asymmetric. Available for Microsoft Windows, Linux, and macOS. SAN File System (SFS) from DataPlow. Available for Windows, Linux, Solaris, and macOS. Symmetric and Asymmetric. EMC Celerra HighRoad from EMC. Available for Linux, AIX, HP-UX, IRIX, Solaris and Windows. Asymmetric. Files-11 on VMSclusters, released by DEC in 1983, now from HP. Symmetric. GFS2 (Global File System) from Red Hat. Available for Linux under GPL. Symmetric (GDLM) or Asymmetric (GULM). IBM General Parallel File System (GPFS) Windows, Linux, AIX . Parallel Nasan Clustered File System from DataPlow. Available for Linux and Solaris. Asymmetric. Oracle ACFS from Oracle Corporation. Available for Linux (Red Hat Enterprise Linux 5 and Oracle Enterprise Linux 5 only). Symmetric. OCFS2 (Oracle Cluster File System) from Oracle Corporation. Available for Linux under GPL. Symmetric. QFS from Sun Microsystems. Available for Linux (client only) and Solaris (metadata server and client). Asymmetric. ScoutFS from Versity. Available for Linux under the GPL. Symmetric. StorNext File System from Quantum. Asymmetric. Available for AIX, HP-UX, IRIX, Linux, macOS, Solaris and Windows. Interoperable with Xsan. Formerly known as CVFS. Veritas Storage Foundation from Symantec. Available for AIX, HP-UX, Linux and Solaris. Asymmetric. Xsan from Apple Inc. Available for macOS. Asymmetric. Interoperable with StorNext File System. VMFS from VMware/EMC Corporation. Available for VMware ESX Server. Symmetric. Distributed file systems Distributed file systems are also called network file systems. Many implementations have been made, they are location dependent and they have access control lists (ACLs), unless otherwise stated below. 9P, the Plan 9 from Bell Labs and Inferno distributed file system protocol. One implementation is v9fs. No ACLs. Amazon S3 Andrew File System (AFS) is scalable and location independent, has a heavy client cache and uses Kerberos for authentication. Implementations include the original from IBM (earlier Transarc), Arla and OpenAFS. Avere Systems has AvereOS that creates a NAS protocol file system in object storage. DCE Distributed File System (DCE/DFS) from IBM (earlier Transarc) is similar to AFS and focus on full POSIX file system semantics and high availability. Available for AIX and Solaris under a proprietary software license. File Access Listener (FAL) is an implementation of the Data Access Protocol (DAP) which is part of the DECnet suite of network protocols created by Digital Equipment Corporation. Magma, developed by Tx0. MapR FS is a distributed high-performance file system that exhibits file, table and messaging APIs. Microsoft Office Groove shared workspace, used for DoHyki NetWare Core Protocol (NCP) from Novell is used in networks based on NetWare. Network File System (NFS) originally from Sun Microsystems is the standard in UNIX-based networks. NFS may use Kerberos authentication and a client cache. OS4000 Linked-OS provides distributed filesystem across OS4000 systems. Self-certifying File System (SFS), a global network file system designed to securely allow access to file systems across separate administrative domains. Server Message Block (SMB) originally from IBM (but the most common version is modified heavily by Microsoft) is the standard in Windows-based networks. SMB is also known as Common Internet File System (CIFS). SMB may use Kerberos authentication. Distributed fault-tolerant file systems Distributed fault-tolerant replication of data between nodes (between servers or servers/clients) for high availability and offline (disconnected) operation. Coda from Carnegie Mellon University focuses on bandwidth-adaptive operation (including disconnected operation) using a client-side cache for mobile computing. It is a descendant of AFS-2. It is available for Linux under the GPL. Distributed File System (Dfs) from Microsoft focuses on location transparency and high availability. Available for Windows under a proprietary software license. HAMMER and HAMMER2 – DragonFly BSD's filesystems for clustered storage, created by Matt Dillon. InterMezzo from Cluster File Systems uses synchronization over HTTP. Available for Linux under GPL but no longer in development since the developers are working on Lustre. LizardFS a networking, distributed file system based on MooseFS Moose File System (MooseFS) is a networking, distributed file system. It spreads data over several physical locations (servers), which are visible to a user as one resource. Works on Linux, FreeBSD, NetBSD, OpenSolaris and macOS. Master server and chunkservers can also run on Solaris and Windows with Cygwin. Scality is a distributed fault-tolerant filesystem. Tahoe-LAFS is an open source secure, decentralized, fault-tolerant filesystem utilizing encryption as the basis for a least-authority replicated design. A FAT12 and FAT16 (and FAT32) extension to support automatic file distribution across nodes with extra attributes like local, mirror on update, mirror on close, compound on update, compound on close in IBM 4680 OS and Toshiba 4690 OS. The distribution attributes are stored on a file-by-file basis in special entries in the directory table. Distributed parallel file systems Distributed parallel file systems stripe data over multiple servers for high performance. They are normally used in high-performance computing (HPC). Some of the distributed parallel file systems use an object storage device (OSD) (in Lustre called OST) for chunks of data together with centralized metadata servers. Lustre is an open-source high-performance distributed parallel file system for Linux, used on many of the largest computers in the world. Parallel Virtual File System (PVFS, PVFS2, OrangeFS). Developed to store virtual system images, with a focus on non-shared writing optimizations. Available for Linux under GPL. Distributed parallel fault-tolerant file systems Distributed file systems, which also are parallel and fault tolerant, stripe and replicate data over multiple servers for high performance and to maintain data integrity. Even if a server fails no data is lost. The file systems are used in both high-performance computing (HPC) and high-availability clusters. All file systems listed here focus on high availability, scalability and high performance unless otherwise stated below. In development: zFS from IBM (not to be confused with ZFS from Sun Microsystems or the zFS file system provided with IBM's z/OS operating system) focus on cooperative cache and distributed transactions and uses object storage devices. Under development and not freely available. HAMMER/ANVIL by Matt Dillon PNFS (Parallel NFS) – Clients available for Linux and OpenSolaris and back-ends from NetApp, Panasas, EMC Highroad and IBM GPFS Coherent Remote File System (CRFS) – requires Btrfs Parallel Optimized Host Message Exchange Layered File System (POHMELFS) and Distributed STorage (DST). POSIX compliant, added to Linux kernel 2.6.30 Peer-to-peer file systems Some of these may be called cooperative storage cloud. Cleversafe uses Cauchy Reed–Solomon information dispersal algorithms to separate data into unrecognizable slices and distribute them, via secure Internet connections, to multiple storage locations. Scality is a distributed filesystem using the Chord peer-to-peer protocol. IPFS InterPlanetary File System is p2p, worldwide distributed content-addressable, file-system. Special-purpose file systems aufs an enhanced version of UnionFS stackable unification file system AXFS (small footprint compressed read-only, with XIP) Barracuda WebDAV plug-in. Secure Network File Server for embedded devices. Boot File System is used on UnixWare to store files necessary for its boot process. cdfs (reading and writing of CDs) Compact Disc File System (reading and writing of CDs; experimental) cfs (caching) Cramfs (small footprint compressed read-only) Davfs2 (WebDAV) Freenet – Decentralized, censorship-resistant FTPFS (FTP access) GmailFS (Google Mail File System) GridFS – GridFS is a specification for storing and retrieving files that exceed the BSON-document size limit of 16 MB for MongoDB. lnfs (long names) LTFS (Linear Tape File System for LTO and Enterprise tape) MVFS – MultiVersion File System, proprietary, used by Rational ClearCase. romfs SquashFS (compressed read-only) UMSDOS, UVFAT – FAT file systems extended to store permissions and metadata (and in the case of UVFAT, VFAT long file names), used for Linux UnionFS – stackable unification file system, which can appear to merge the contents of several directories (branches), while keeping their physical content separate Venti – Plan 9 de-duplicated storage used by Fossil. WBFS – Wii Backup FileSystem Pseudo file systems devfs – a virtual file system in Unix-like operating systems for managing device nodes on-the-fly procfs – a pseudo-file system, used to access kernel information about processes tmpfs – in-memory temporary file system (on Unix-like platforms) sysfs – a virtual file system in Linux holding information about buses, devices, firmware, filesystems, etc. debugfs – a virtual file system in Linux for accessing and controlling kernel debugging configfs – a writable file system used to configure various kernel components of Linux sysctlfs – allow accessing sysctl nodes via a file system; available on NetBSD via PUFFS, FreeBSD kernel via a 3rd-party module, and Linux as a part of Linux procfs. kernfs – a file system found on some BSD systems (notably NetBSD) that provides access to some kernel state variables; similar to sysctlfs, Linux procfs and Linux sysfs. wikifs – a server application for Plan 9's virtual, wiki, file system Encrypted file systems eCryptfs – a stacked cryptographic file system in the Linux kernel since 2.6.19 Secure Shell File System (SSHFS) – locally mount a remote directory on a server using only a secure shell login. EncFS, GPL Encrypted file system in user-space Rubberhose filesystem EFS – an encrypted file system for Microsoft Windows systems and AIX. An extension of NTFS ZFS, with encryption support. File system interfaces These are not really file systems; they allow access to file systems from an operating system standpoint. FUSE (file system in userspace, like LUFS but better maintained) LUFS (Linux userland file system – seems to be abandoned in favour of FUSE) PUFFS (Userspace filesystem for NetBSD, including a compatibility layer called librefuse for porting existing FUSE-based applications) VFS Virtual Filesystem See also Shared file access Comparison of file systems Filing OSID Computer storage References External links File Systems File systems

Operating System (OS)

Tinix Tinix (Try It as miNIX-like operating system), is a tutorial operating system (OS) written by Yu Yuan. It is used to teach fundamentals rather than to do work. In his book "Writing OS DIY", Yu provides all source code for Tinix. Tinix borrows many concepts and methods from Minix. The book compensates for practical computer programming skills, especially in x86 assembly language, lacking in Andrew S. Tanenbaum's book "Operating Systems: Design and Implementation", 1987, 1997, 2006. References Unix variants Free software operating systems Microkernels Microkernel-based operating systems Educational operating systems

Operating System (OS)

GOS (operating system) gOS or "good OS" was an Ubuntu-based Linux distribution created by Good OS LLC, a Los Angeles-based corporation. Its CIO David Liu described that after meeting Enlightenment and open source people, he realized that his dream to bring Web 2.0 applications into mainstream use could be achieved by creating a Linux distribution that made it easy for users to access Google and Web 2.0 applications. David Liu went on to create the Chinese Twitter clone called Wozai (), leaving gOS officially defunct. History The company initially advertised gOS 1.0 as "An alternative OS with Google Apps and other Web 2.0 apps for the modern user." This first version of gOS (1.0.1_386) was based on Ubuntu 7.10 and the Enlightenment window manager E17. On January 7, 2008, a test version (2.0.0-beta1) of gOS, intended to demonstrate the Everex CloudBook at the 2008 Consumer Electronics Show, and named gOS Rocket, was released. This version was also E17-based. The definitive second version of gOS debuted at the end February 2008, together with the launch of Everex's new CloudBook, the gBook laptop, and a new, second version of the gPC, the "encore". This version was called gOS V2 Rocket, and was completely rewritten and now based on the GNOME window manager, a built in Compositing window manager, and the Avant Window Navigator. On April 6, 2008, Good OS launched a publicly available version of gOS, called gOS 2.9 "Space", intended for the gPC mini, This version is based on Compiz fusion, Gnome, and the Avant Window Navigator dock manager, but also uses E17 code. It has a dock with a "stack" very much like the "fan view" of Mac OS X v10.5. On September 23, 2008, Good OS launched gOS 3 Gadgets, which is described by Good OS, as "The third and best version of gOS to date, Perfect for Netbooks". It is still based on GNOME but has replaced AWN with yet another launcher called Wbar. It introduces the full support for Wine 1.0, Picasa (using the Wine libraries) and Google Gadgets. On December 1, 2008, Good OS announced its next operating system, Cloud. Cloud can be described as an "instant-on browser-based application environment". With Cloud, users can browse the Internet seconds after turning on their computer, and can also use it to run applications, like Skype, or a media player. Cloud shows a Dock similar to gOS 3 in the browser window, and will keep loading the main operating system (Windows, Linux, OSX) in the background. An icon in the Dock will tell the user when the main OS has finished booting in the background, and can be used to switch instantly to the main OS, when tasks not (yet) supported under Cloud are needed. A beta test program for Cloud version 1.0 was announced January 30, 2009. On January 3, 2009, Good OS released gOS 3.1 Gadgets (SP1), or Service pack 1, a bug-fixed version of gOS 3.0. Simultaneously, the Good OS team also launched a new official forum, as a replacement for the Google discussion group used previously and faqly, which is now defunct. Faqly was a cross between an Internet forum and a FAQ where gOS users could ask questions and browse for answers. Other gOS users, or Linux experts, could then provide answers to the questions. But Faqly had some large usability problems, notably the fact that users had problems deciding when the system was searching for an answer, or entering a new question. Additionally, questions and answers could not be edited or deleted. Around May 2008, members of the Good OS team ceased posting online from gOS-associated accounts, including their own forum and website. While the website was still on-line, and gOS 3.1 could be downloaded, no sources of gOS are available. Development of gOS seems to have been stalled, and the official forum at forum.thinkgos.com was not moderated anymore and was quickly overrun by spam and was closed halfway through 2009 (one of the few life-signs of the Good OS team after mid 2008); its function has been taken over by the unofficial forum. No sign of promised developments like the netbook launcher version or cloud have been realized. The official GOS page www.thinkgos.com was last captured live by Internet Archive Wayback Machine on January 13, 2011; the next capture from February 2, 2011 is of the website yielding a "Site Temporarily Unavailable" message with an error code id "bad_httpd_conf". As of 2015, the thinkgos.com domain is no longer owned by David Liu. and no web site is configured for the domain. According to DistroWatch.com, gOS is discontinued. Design gOS-1 was based on the Ubuntu 7.10 distribution (later versions after 2.9 use version 8.04) and themed desktop environment somewhat similar in appearance to Mac OS X Leopard. The earlier versions (1 and 2-beta) used the Enlightenment 17 window manager instead of the usual GNOME or KDE desktops, to create a desktop that had a similar appearance to Mac OS X. Enlightenment acted both as an X window manager and a desktop environment. Therefore, early versions of gOS worked on systems as low end as a 350 MHz Pentium II with 196 MB of RAM, but a typical gOS system would have used as a minimum a 1 GHz Pentium III with 256 MB RAM. After gOS2-beta the later versions of gOS abandoned the use of Enlightenment as desktop manager (although some E17 code still seemed to be used), in favor of using GNOME, with Compiz Fusion and the Avant Window Navigator. This increased the need for memory to values similar to normal Ubuntu. Based on the idea of cloud computing, all versions of gOS lean heavily on on-line applications built on Web 2.0 and AJAX technology so they also do not use much hard disk space for applications. The whole gOS-1 system fitted comfortably in less than 2 GB. Also many of the documents created with gOS, such as Google Docs documents, can be saved on Google servers instead of on the local hard disk, so gOS can work with very small hard disks. In gOS V2 Rocket, Good OS introduced the use of Google's "Google Gears" technology which promises to make Google's web applications usable without an Internet connection. Currently, Google Reader and Google Docs are the only supported Google applications, though other web applications such as Remember the Milk have added Google Gears functionality. gOS 2.0 Rocket's primary features include a Mac OS X-like Dock called "the Launcher" (using Avant Window Navigator in gOS Rocket G and gOS Space, and iTask-NG in gOS Rocket E), containing icons to launch programs like the Firefox web browser, Rhythmbox audio player, Xine video player, and Skype for Internet telephony. There are also options to open many Google-based web application like Google Mail, Google Docs, Google Calendar, and Google Maps. Other programs could be added to the Launcher as well. The first E17-based version of gOS used another Dock-style interface called the iBar. Other installed programs could be started through menus, among the most important was the photo and picture editing program the GIMP, the document viewer Evince, and the OpenOffice.org office suite. More programs could be installed using the built-in Synaptic Package Manager. Versions gOS 1.0.1 gOS 1.0.1 was introduced on November 1, 2007, preinstalled on the Everex Green gPC TC2502 sold at Wal-Mart. gOS 1.0.1 fully supported the advanced Power management capabilities of the gPC TC2502, so the system could be put in suspend mode and after turning on again was ready in a few seconds. In December 2007, PC Club followed suit and reintroduced their Enpower Fuzion desktop for sale with gOS installed for $189, which is their second system to include a Linux distribution since their controversial temporary inclusion of Linspire (then LindowsOS) in late 2003/early 2004 and the sale of the Empower Essence system with Ubuntu during the month of June 2007. Everex followed on by creating the CloudBook, a laptop based on the VIA NanoBook reference. The CloudBook was bundled with gOS Rocket with a hint that later versions would include a touchscreen. At an RRP of $400, it was to compete with the ASUS Eee PC in the cheap miniature Laptop space. Less well known is the fact that Everex simultaneously also worked on a more classic notebook, called the gBook, and on the Mac mini like gPC mini all designed to run gOS v2. Online vendor ClubIT.com offered a RoHS-compliant VIA C7 developer board bundled with gOS. gOS 2-beta (gOS Rocket E) On 2008-01-07, Good OS LLC released a beta of the second version of gOS, called gOS-live-2.0.0-beta1 and nicknamed "Rocket". However this version did not seem to be a valid replacement for rev 1.0.1 as it was missing some essential functions, such as hardware and system administration tools, and the easy to use application installer "Add/Remove". It also missed the capability to access CDs and hard-disk partitions other than its own. The demo version status of this version became extra apparent when the new Everex CloudBook which was due to debut January 25, 2008 was delayed for a month to allow Good OS time to rewrite this second version of gOS for the CloudBook, gBook. and second version of the gPC. On April 11, 2008, Good OS released an updated version of gOS Rocket E. In addition, a fan of gOS has also released an unauthorized remaster of gOS Rocket E which includes the aforementioned system administration tools and drive mounting as well as the Thunar file manager. gOS V2 Rocket (gOS Rocket G) Later it became apparent that the month was needed because Everex had decided that future versions of gOS for the Cloudbook, gBook and gPC2, would use the GNOME desktop environment, instead of E17. It was announced that this version would also be called "Rocket", to be precise gOS V2 "Rocket", (this version would also be offered to new gPC2 users) and would use the Avant Window Navigator system to create a dock to resemble the older gOS versions in looks and functionality. Until the launch of gOS 2.9 this version was not available as a Live CD, but only to CloudBook owners. But after the launch of 2.9 it has now also become available as a Live_CD download from one of the mirrors as found on the Good OS web-site. This version is now referenced to as "gOS rocket G" ("G" for Gnome) to distinguish it from the older beta version now called "gOS rocket E", which is also still available for download. gOS 2.9 Space gOS 2.9 Space became available as a generic Linux distribution on April 7, 2008, and is a debugged and extended version of the older gOS V2 Rocket G. It can be downloaded as an .ISO that can be burned on a DVD (it is slightly too large for a CD), or can be put on another external bootable medium such as a memory stick or Secure Digital card reader acting as an external USB drive, with enough capacity. A gOS 2.9 DVD was also announced to be sold from The Good OS store on their website, but until now has not become available. gOS Space is loaded with new MySpace features, but all the existing Google applications can still be used. As a Linux distribution, 2.9 is much more complete than 2.0-beta and is also less buggy. gOS Space is less "light" (using a small amount of memory) than older, publicly available versions, as it is based on a combination of Ubuntu 7.10, the GNOME windows manager enhanced with Compiz fusion, and the Avant Window Navigator, a Dock-like launcher that has been enhanced with Stacks. According to Good OS, there is also Enlightenment code used, but its exact purpose is still unknown. In any case gOS Space needs about 384MB of RAM to work reasonably, the same amount as straight Ubuntu 7.10. When Ubuntu 8.04 (Hardy Heron) became available on April 24, 2008 it became obvious that trying to upgrade gOS 2.9 to the new Ubuntu renders it without any working kernels, leaving a non-working system, so upgrading gOS has been disabled by Good OS. It is not expected that this will be fixed, but that instead a new gOS (rev 3.0) will be released, based on Ubuntu 8.04. gOS 2.9M Escape Pod As of July 2, 2008 Good OS, in consortium with Digital Gadgets, launched the Sylvania g netbook. The Sylvania name is used under license by Digital Gadgets. Its similar to the original Everex CloudBook with more memory, and the trackpad and buttons have moved to the front of the device. the new system runs gOS 2.9M, a specially modified version of gOS 2.9 "space" based on Ubuntu 8.04 gOS 3.0 Gadgets About a month after a first beta version, the final version of gOS 3.0 was released on the gOS website on September 23, 2008. It features integrated Google Gadgets integrated into the desktop (not in a browser window) and includes Wine 1.0 and Mozilla Prism. gOS 3.0 is based on the newer Ubuntu 8.04.1. This version goes "back to its roots", as it is intended for netbooks. The Avant Window Navigator's (abbreviated AWN or Awn) dock-like bar has been removed in favor of a more "lightweight" launch bar called Wbar. It is similar to the one used in the first Enlightenment-based gOS version. The gOS 3.0 Gadgets Live CD can be downloaded from the thinkgos site. In an official press release issued on August 6, 2008, gOS 3.0 Gadgets was announced to use LXDE technology but this plan was later put aside. Launching Synaptic will reveal that none of the applications listed at LXDE's About page are installed. gOS 3.1 Gadgets gOS 3.1 Gadgets was launched on January 3, 2009 as an upgraded bug fixed version of gOS 3.0 gadgets. This version fixes some bugs in gOS 3.0, but it isn't an obligatory update for users of 3.0 because bugfixes in gOS 3.0 are distributed using the built-in updater automatically. This version has had over 45,000 downloads. Netbook Launcher On October 22, 2008, a beta version of the gOS Netbook Launcher was released. This is an independently developed extension of gOS that gives gOS 3.0 Gadgets the possibility to switch to a new "netbook user interface", similar to Ubuntu Netbook Remix. You can switch between a netbook user interface and the classic gOS desktop at will. This Launcher is provided by the gOS Community and is not officially supported by Good OS for system manufacturers. It is still in beta, and therefore contains some bugs. One remaining problem is that it does not work well with Compiz. Upgrade problem for versions before gOS 2.9M When Ubuntu released version 8.04 (Hardy Heron) on April 24, 2008, it became apparent that gOS (versions before gOS 2.9M Escape pod) could no longer use the update/upgrade facilities that Ubuntu offered. Any attempt to upgrade any version of gOS before version 2.9M will either fail with an "incompatible windows manager" error or will remove all kernels from the system. Version 3.0 of gOS solves the problem, as it is actually based on Ubuntu 8.04. Good OS claims that new versions of gOS won't use Ubuntu's upgrading repositories, to prevent the problem from happening again. Version history table Live USB A Live USB of gOS can be created manually or with UNetbootin. See also EasyPeasy Everex green computers Goobuntu Google Chrome OS Joli OS LXDE Zonbu References External links Official website, (down as of early march 2011) gOS Archive and downloads Discontinued Linux distributions Ubuntu derivatives Cloud clients Everex Linux distributions

Operating System (OS)

Commodore OS Commodore OS (full name: Commodore OS Vision) was a free-to-download Linux distribution developed by Commodore USA and intended for Commodore PCs. The distribution was based on Linux Mint, available only for x86-64 architectures, and used the GNOME 2 desktop environment. The first public beta version was released on 11 November 2011. It has been continually updated through Commodore OS Vision 0.8 Beta and never came out of beta phase. 1.0 did come out of Beta and was released on DistroWatch.com. This operating system is no longer in development. The company is now closed and its web site is no longer active. History The first beta release of the OS was released on 12 November 2011, announced as an operating system for "pre-installation on all future Commodore USA hardware". Commodore USA went defunct in 2013, the website hosting the OS is down and its last release was on 9 July 2012. However, it continues to have a small community support - with an unofficial 32 bit version of the operating system released on 22 February 2012. Compatibility Commodore OS was not compatible with Commodore 64 software. However, it did contain VICE, an open-source program which emulates Commodore systems. Design Commodore OS was designed as a way to imitate the look and feel of Commodore's legacy systems, and as a complement to the all-in-one-keyboard style of the personal computer. Commodore OS includes a collection of software intended to imitate classic Commodore software. It was fully compatible only to Commodore USA products often causing kernel panic on general PCs. An Improved Fusion version was promised but never released. References External links Commodore OS Website (Defunct) Commodore OS archive Customize Linux Mint in Commodore OS Vision [Italian] 2011 software Commodore 64 Debian-based distributions Ubuntu derivatives Linux distributions

Operating System (OS)

Windows 1.0x Windows 1.0 is a graphical operating environment for personal computers, developed by Microsoft. Microsoft had worked with Apple Computer to develop applications for Apple's 1984 original Macintosh, the first mass-produced personal computer with a graphical user-interface (GUI) that enabled users to see user-friendly icons on screen. Microsoft released Windows 1.0 on November 20, 1985, as the first version of the Microsoft Windows line. It is a type of software that runs as a graphical, 16-bit multi-tasking shell on top of an existing MS-DOS installation, providing an environment which can run graphical programs designed for Windows, as well as existing MS-DOS software. Microsoft's founder Bill Gates spearheaded the development of Windows 1.0 after he saw a demonstration of a similar software suite, Visi On, at COMDEX in 1982. Despite positive responses to early presentations and support from a number of hardware- and software-makers, critics received Windows 1.0 poorly, feeling that it did not meet their expectations. In particular, they raised concerns about the lack of resources for new users, and performance issues, especially on systems with lower hardware specifications. Despite the criticisms, Windows 1.0 proved an important milestone for Microsoft, as it introduced the Microsoft Windows line. On December 31, 2001, Microsoft declared Windows 1.0 obsolete and stopped providing support and updates for the system. Windows 1.01 was released in the United States in November 20, 1985, while the European version was released as Windows 1.02 in January 1986. History Microsoft began developing the graphical user interface (GUI) in 1981. The development of Windows began after Microsoft founder Bill Gates saw a demonstration at COMDEX 1982 of VisiCorp's Visi On, a GUI software suite for IBM PC compatible computers. In 1983 Microsoft learned that Apple's own GUI software—also bit-mapped, and based in part on research from Xerox PARC—was much more advanced; Microsoft decided they needed to differentiate their own offering. In August 1983, Gates recruited Scott McGregor, one of the key developers behind PARC's original windowing system, to be the developer team lead for Windows 1.0. Microsoft first presented Windows to the public on November 10, 1983. Requiring two floppy disk drives and 192 KB of RAM, Microsoft described the software as a device driver for MS-DOS 2.0. By supporting cooperative multitasking in tiled windows when using well-behaved applications that only used DOS system calls, and permitting non-well-behaved applications to run in a full screen, Windows differed from both Visi On and Apple Computers Lisa by immediately offering many applications. Unlike Visi On, Windows developers did not need to use Unix to develop IBM PC applications; Microsoft planned to encourage other companies, including competitors, to develop programs for Windows by not requiring a Microsoft user interface in their applications. Many manufacturers of MS-DOS computers such as Compaq, Zenith, and DEC promised to provide support, as did software companies such as Ashton-Tate and Lotus. After previewing Windows, BYTE magazine stated in December 1983 that it "seems to offer remarkable openness, reconfigurability, and transportability as well as modest hardware requirements and pricing … Barring a surprise product introduction from another company, Microsoft Windows will be the first large-scale test of the desktop metaphor in the hands of its intended users". From early in Windows' history Gates viewed it as Microsoft's future. He told InfoWorld magazine in April 1984 that "Our strategies and energies as a company are totally committed to Windows, in the same way that we're committed to operating-system kernels like MS-DOS and Xenix. We're also saying that only applications that take advantage of Windows will be competitive in the long run." IBM was notably absent from Microsoft's announcement, and by late 1984, the press reported a "War of the Windows" between Windows, IBM TopView, and Digital Research's Graphics Environment Manager (GEM). Microsoft had promised in November 1983 to ship Windows by April 1984, but subsequently denied that it had announced a release date, and predicted that Windows would ship by June 1985. During its development and before its windowing system was developed, it was briefly referred to by the codename "Interface Manager". De-emphasizing multitasking, the company stated that Windows' purpose, unlike that of TopView, was to "turn the computer into a graphics-rich environment" while using less memory. After Microsoft persuaded IBM that the latter needed a GUI, in April 1987 the two companies announced the introduction of OS/2 and its graphical OS/2 Presentation Manager, which were supposed to ultimately replace both MS-DOS and Windows. Release versions: Windows 1.01–1.04 The first retail release, Windows 1.01, was released in November 20, 1985 to the United States. Windows version 1.02, was released in January 1986 for the European market. Windows version 1.03, released in August 1986, included enhancements that made it consistent with the international release like drivers for European keyboards and additional screen and printer drivers, and superseded both version 1.01 in the US and version 1.02 in Europe. Windows version 1.04, released in April 1987, added support for the new IBM PS/2 computers, although no support for PS/2 mice or new VGA graphics modes was provided. However, on May 27, 1987, an OEM version was released by IBM, which added VGA support, PS/2 mouse support, MCGA support, and support for the 8514/A display driver. IBM released this version on three 3.5 inch 720k floppies, and offered it as part of their "Personal Publishing System" and "Collegiate Kit" bundles. Microsoft supported Windows 1.0 for 16 years, until December 31, 2001 – the longest out of all versions of Windows. Succession: Windows 2.0 In December 1987, Windows 1.0 was succeeded by Windows 2.0. Features Windows 1.0 offers limited multitasking of existing MS-DOS programs and concentrates on creating an interaction paradigm (cf. message loop), an execution model and a stable API for native programs for the future. Due to Microsoft's extensive support for backward compatibility, it is not only possible to execute Windows 1.0 binary programs on current versions (albeit only 32-bit) of Windows to a large extent, but also to recompile their source code into an equally functional "modern" application with just limited modifications. Windows 1.0 is often regarded as a "front-end to the MS-DOS operating system", a description which has also been applied to subsequent versions of Windows. Windows 1.0 is an MS-DOS program. Windows 1.0 programs can call MS-DOS functions, and GUI programs are run from .exe files just like MS-DOS programs. However, Windows .exe files had their own "new executable" (NE) file format, which only Windows could process and which, for example, allowed demand-loading of code and data. Applications were supposed to handle memory only through Windows' own memory management system, which implemented a software-based virtual memory scheme allowing for applications larger than available RAM. Because graphics support in MS-DOS is extremely limited, MS-DOS applications have to go to the bare hardware (or sometimes just to the BIOS) to get work done. Therefore, Windows 1.0 included original device drivers for video cards, a mouse, keyboards, printers and serial communications, and applications were supposed to only invoke APIs built upon these drivers. However, this extended to other APIs such as file system management functions. In this sense, Windows 1.0 was designed to be extended into a full-fledged operating system, rather than being just a graphics environment used by applications. Indeed, Windows 1.0 is a "DOS front-end" and cannot operate without a DOS environment (it uses, for example, the file-handling functions provided by DOS). The level of replacement increases in subsequent versions. The system requirements for Windows 1.01 constituted CGA/HGC/EGA (listed as "Monochrome or color monitor"), MS-DOS 2.0, 256 KB of memory or greater, and two double-sided disk drives or a hard drive. Beginning with version 1.03, support for Tandy and AT&T graphics modes was added. Windows 1.0 runs a shell program known as the MS-DOS Executive, which is little more than a mouse-able output of the DIR command that does not support icons and is not Y2K-compliant. Other supplied programs are Calculator, Calendar, Clipboard Viewer, Clock, Notepad, Paint, Reversi, Cardfile, Terminal and Write. Windows 1.0 does not allow overlapping windows. Instead all windows are tiled. Only dialog boxes can appear over other windows, but cannot be minimized. Reception Windows 1.0 was released to negative reviews. Most critics considered the platform to have future potential, but that Windows 1.0 had not fulfilled expectations. Many reviews criticized its demanding system requirements, especially noting the poor performance experienced when running multiple applications at once, and that Windows encouraged the use of a mouse for navigation, a relatively new concept at the time. The New York Times compared the performance of Windows on a system with 512 KB of RAM to "pouring molasses in the Arctic", and that its design was inflexible for keyboard users due to its dependency on a mouse-oriented interface. In conclusion, the Times felt that the poor performance, lack of dedicated software, uncertain compatibility with DOS programs, and the lack of tutorials for new users made DOS-based software such as Borland Sidekick (which could provide a similar assortment of accessories and multitasking functionality) more desirable for most PC users. In retrospect, Windows 1.0 was regarded as a flop by contemporary technology publications, who, however, still acknowledged its overall importance to the history of the Windows line. Nathaniel Borenstein (who went on to develop the MIME standards) and his IT team at Carnegie Mellon University were also critical of Windows when it was first presented to them by a group of Microsoft representatives. Underestimating the future impact of the platform, he believed that in comparison to an in-house window manager, "these guys came in with this pathetic and naïve system. We just knew they were never going to accomplish anything." The Verge considered the poor reception towards the release of Windows 8 in 2012 as a parallel to Microsoft's struggles with early versions of Windows. In a similar fashion to Windows 1.0 running atop MS-DOS as a layer, Windows 8 offered a new type of interface and software geared towards an emerging form of human interface device on PCs, in this case, a touchscreen, running atop the legacy Windows shell used by previous versions. A mock version of Windows 1.0 was created by Microsoft as an app for Windows 10 as part of a tie-in with the Netflix show, Stranger Things, aligned with the release of the show's third season, which takes place during 1985. See also Comparison of file managers DESQview OS/2 System 1 on Macintosh TopView References External links Demo of Windows 1.04 running on an original IBM PC/XT, on YouTube Windows 1.01 emulator 1985 software 1.0x Products and services discontinued in 2001

Operating System (OS)

TrueOS TrueOS (formerly PC-BSD or PCBSD) is a discontinued Unix-like, server-oriented operating system built upon the most recent releases of FreeBSD-CURRENT. Up to 2018 it aimed to be easy to install by using a graphical installation program, and easy and ready-to-use immediately by providing KDE SC, Lumina, LXDE, MATE, or Xfce as the desktop environment. In June 2018 the developers announced that since TrueOS had become the core OS to provide a basis for other projects, the graphical installer had been removed. Graphical end-user-orientated OSes formerly based on TrueOS were GhostBSD and Trident. TrueOS provided official binary Nvidia and Intel drivers for hardware acceleration and an optional 3D desktop interface through KWin, and Wine is ready-to-use for running Microsoft Windows software. TrueOS was also able to run Linux software in addition to FreeBSD Ports collection and it had its own .txz package manager. TrueOS supported OpenZFS and the installer offered disk encryption with geli. Development of TrueOS ended in 2020. History TrueOS was founded by FreeBSD professional Kris Moore in early 2005 as PC-BSD. In August 2006 it was voted the most beginner-friendly operating system by OSWeekly.com. The first beta of the PC-BSD consisted of only a GUI installer to get the user up and running with a FreeBSD 6 system with KDE3 pre-configured. This was a major innovation for the time as anyone wishing to install FreeBSD would have to manually tweak and run through a text installer. Kris Moore's goal was to make FreeBSD easy for everyone to use on the desktop and has since diverged even more in the direction of usability by including additional GUI administration tools and .pbi application installers. PC-BSD's application installer management involved a different approach to installing software than many other Unix-like operating systems, up to and including version 8.2, by means of the pbiDIR website. Instead of using the FreeBSD Ports tree directly (although it remained available), PC-BSD used files with the .pbi filename extension (Push Button Installer) which, when double-clicked, brought up an installation wizard program. An autobuild system tracked the FreeBSD ports collection and generated new .pbi files daily. All software packages and dependencies were installed from inside of the .pbi files in their own self-contained directories in /Programs. This convention was aimed to decrease confusion about where binary programs reside, and to remove the possibility of a package breaking if system libraries are upgraded or changed, and to prevent dependency hell. On October 10, 2006, PC-BSD was acquired by enterprise hardware provider iXsystems. iXsystems employed Kris Moore as a full-time developer and leader of the project. In November 2007, iXsystems entered into a distribution agreement with Fry's Electronics whereby Fry's Electronics stores nationwide carry boxed copies of PC-BSD version 1.4 (Da Vinci Edition). In January 2008, iXsystems entered into a similar agreement with Micro Center. On September 1, 2016, the PC-BSD team announced that the name of the operating system would change to TrueOS. Along with the rebranding, the project also became a rolling release distribution, based on the FreeBSD-CURRENT branch. On November 15, 2016, TrueOS began the transition from FreeBSD's rc.d to OpenRC as the default init system. Apart from Gentoo/Alt, where OpenRC was initially developed, this is the only other major BSD based operating system using OpenRC. In July 2018, TrueOS announced that they would spin off the desktop edition into a separate project named Project Trident. Development of TrueOS ended in 2020 and the developers recommended users move to other BSD-based operating systems. Release history Since version 7, PC-BSD began following the same numbering system as FreeBSD. Since version 9.0, the KDE SC, customized to support tighter application integration and the .txz package management system, was no longer the only desktop environment supported by PC-BSD. While manual installation of other desktops such as Xfce and GNOME had been technically possible in earlier releases, none of these were supported in the earlier versions, and major functionality was lost when not using PC-BSD's special build of KDE SC. Starting with version 9.0, PC-BSD added other desktop environments, including GNOME, Xfce, LXDE, and MATE. PC-BSD used to support both amd64 and i686 architectures. Support for i686 was dropped in version 9.2. Starting in September 2016 with the rebranding of PC-BSD, TrueOS became a rolling release distribution based on FreeBSD's current branch. Package management TrueOS's package manager takes a similar approach to installing software to many other Unix-like operating systems. Instead of using the FreeBSD Ports tree directly (although it remains available), TrueOS uses files with the .txz filename extension packages which contain compiled ports. An autobuild system tracks the FreeBSD ports collection and generates new .txz files daily. The TrueOS package management system aims to be visually similar to that of major operating systems such as Microsoft Windows and Apple macOS, where applications are installed from a single download link with graphical prompts, while maintaining internally the traditional .txz package management systems that many Unix-like systems use. The TrueOS package manager also takes care of creating categorized links in the KDE menu and on the KDE SC desktop. Lumina Desktop In 2014, the PC-BSD project announced its development of a new desktop environment, from scratch, named Lumina. Ken Moore is the main developer of Lumina, which is based on the Qt toolkit. As of July 2016, Lumina has its own web site. The desktop environment is not an application development toolkit, and aims to be a graphical interface that only uses plugins for customization. License TrueOS was originally licensed under the GNU General Public License (GPL) because the developers were under the impression that applications using the Qt, which TrueOS uses for its interface development, must be licensed under the GPL or the Q Public License. Upon discovering that there was, in fact, no such restriction, the TrueOS developers later relicensed the code under a BSD-like 3-clause license. TrueOS and the TrueOS logo are registered trademarks of iXsystems Inc. Hardware requirements The New York City *BSD User Group runs a service named dmesgd, which provides user-submitted dmesg information for different computer hardware (laptops, workstations, single-board computers, embedded systems, virtual machines, etc.) capable of running TrueOS. According to the TrueOS wiki, TrueOS has the following hardware requirements: Minimum amd64 processor 1 GiB of RAM 20 GiB free hard drive space Network card Recommended amd64 processor EFI system partition for installation of rEFInd 4 GiB of RAM 30 GiB of free hard drive space on a primary partition for a desktop installation, or 20 GiB for a server installation 50 GiB is recommended for installations with backup services 3D accelerated video card Network card Sound card UEFI UEFI support (for amd64 only) has been added to the installer and the boot manager since version 10.1 with the default EFI boot manager to be rEFInd. This includes ACPI detection and setup of Root System Description Pointer (RSDP), eXtended System Descriptor Table (XSDT), and Root System Description Table (RSDT) pass-through values to the kernel. A new installation is needed in order to install UEFI support as it requires the creation of a small FAT partition. The current UEFI does not support secure boot. Gallery See also Comparison of BSD operating systems Notes References External links TrueOS software repository DistroWatch Interview with Kris Moore on DistroWatch Interview with Kris Moore on FLOSS Weekly 2006 software FreeBSD KDE

Operating System (OS)

Interactive Systems Corporation Interactive Systems Corporation (styled INTERACTIVE Systems Corporation, abbreviated ISC) was a US-based software company and the first vendor of the Unix operating system outside AT&T, operating from Santa Monica, California. It was founded in 1977 by Peter G. Weiner, a RAND Corporation researcher who had previously founded the Yale University computer science department and had been the Ph. D. advisor to Brian Kernighan, one of Unix's developers at AT&T. Weiner was joined by Heinz Lycklama, also a veteran of AT&T and previously the author of a Version 6 Unix port to the LSI-11 computer. ISC was acquired by the Eastman Kodak Company in 1988, which sold its ISC Unix operating system assets to Sun Microsystems on September 26, 1991. Kodak sold the remaining parts of ISC to SHL Systemhouse Inc in 1993. Several former ISC staff founded Segue Software which partnered with Lotus Development to develop the Unix version of Lotus 1-2-3 and with Peter Norton Computing to develop the Unix version of the Norton Utilities. Products ISC's 1977 offering, IS/1, was a Version 6 Unix variant enhanced for office automation running on the PDP-11. IS/3 and IS/5 were enhanced versions of Unix System III and System V for PDP-11 and VAX. ISC Unix ports to the IBM PC included a variant of System III, developed under contract to IBM, known as PC/IX (Personal Computer Interactive eXecutive, also abbreviated PC-IX), with later versions branded 386/ix and finally INTERACTIVE UNIX System V/386 (based on System V Release 3.2). ISC was AT&T's "Principal Publisher" for System V.4 on the Intel platform. ISC was also involved in the development of VM/IX (Unix as a guest OS in VM/370) and enhancements to IX/370 (a TSS/370-based Unix system that IBM originally developed jointly with AT&T ca. 1980). They also developed the AIX 1.0 (Advanced Interactive eXecutive) for the IBM RT PC, again under contract to IBM, although IBM awarded the development contract for AIX version 2 of AIX/386 and AIX/370 to the competing Locus Computing Corporation. PC/IX Although observers in the early 1980s expected that IBM would choose Microsoft Xenix or a version from AT&T Corporation as the Unix for its microcomputer, PC/IX was the first Unix implementation for the IBM PC XT available directly from IBM. According to Bob Blake, the PC/IX product manager for IBM, their "primary objective was to make a credible Unix system - [...] not try to 'IBM-ize' the product. PC-IX is System III Unix." PC/IX was not, however, the first Unix port to the XT: Venix/86 preceded PC/IX by about a year, although it was based on the older Version 7 Unix. The main addition to PC/IX was the INed screen editor from ISC. INed offered multiple windows and context-sensitive help, paragraph justification and margin changes, although it was not a fully fledged word processor. PC/IX omitted the System III FORTRAN compiler and the tar file archiver, and did not add BSD tools like vi or the C shell. One reason for not porting these was that in PC/IX, individual applications were limited to a single segment of 64 kB of RAM. To achieve good filesystem performance, PC/IX addressed the XT hard drive directly, rather than doing this through the BIOS, which gave it a significant speed advantage compared to MS-DOS. Because of the lack of true memory protection in the 8088 chips, IBM only sold single-user licenses for PC/IX. The PC/IX distribution came on 19 floppy disks and was accompanied by a 1,800-page manual. Installed, PC/IX took approximately 4.5 MB of disk space. An editorial by Bill Machrone in PC Magazine at the time of PC/IX's launch flagged the $900 price as a show stopper given its lack of compatibility with MS-DOS applications. PC/IX was not a commercial success although BYTE in August 1984 described it as "a complete, usable single-user implementation that does what can be done with the 8088", noting that PC/IX on the PC outperformed Venix on the PDP-11/23. INTERACTIVE UNIX System PC/IX was succeeded by 386/ix in 1985, a System VR3 derivative. Later versions were termed INTERACTIVE UNIX System V/386 and based on System V 3.2, though with elements of BSD added. Its SVR3.2 kernel meant diminished compatibility with other Unix ports in the early nineties, but the INTERACTIVE UNIX System was praised by a PC Magazine reviewer for its stability. After its acquisition of Interactive, Sun Microsystems continued to maintain INTERACTIVE UNIX System, offering it as a low-end alternative to its System V.4-based Solaris, even when the latter had been ported to x86-based desktop machines. The last version was "System V/386 Release 3.2 Version 4.1.1", released in July 1998. Official support ended on July 23, 2006, five years after Sun withdrew the product from sale. Until version ISA 3.0.1, INTERACTIVE UNIX System supported only 16 MB of RAM. In the next versions, it supported 256 MB RAM and the PCI bus. EISA versions always supported 256 MB RAM. See also Coherent (operating system) Notes References Further reading Covers and compares PC/IX, Xenix, and Venix. Maurice J. Bach, The Design of the UNIX Operating System, , Prentice Hall, 1986. IBM has snubbed both Microsoft's multimillion dollar investment in Xenix and AT&T's determination to establish System V as the dominant version on Unix. (InfoWorld 20 Feb 1984) IBM's latest hot potato (PC Mag 20 Mar 1984) External links Interactive Unix Documentation Defunct software companies of the United States Unix history Unix variants

Operating System (OS)

Real-time operating system A real-time operating system (RTOS) is an operating system (OS) for real-time applications that processes data and events that have critically defined time constraints. An RTOS is distinct from a time sharing operating system, such as Unix, which manages the sharing of system resources with a scheduler, data buffers, or fixed task prioritization in a multitasking or multiprogramming environment. Processing time requirements need to be fully understood and bound rather than just kept as a minimum. All processing must occur within the defined constraints. Real-time operating systems are event-driven and preemptive, meaning the OS is capable of monitoring the relevant priority of competing tasks, and make changes to the task priority. Event-driven systems switch between tasks based on their priorities, while time-sharing systems switch the task based on clock interrupts. Characteristics A key characteristic of an RTOS is the level of its consistency concerning the amount of time it takes to accept and complete an application's task; the variability is 'jitter'. A 'hard' real-time operating system (hard RTOS) has less jitter than a 'soft' real-time operating system (soft RTOS). A late answer is a wrong answer in a hard RTOS while a late answer is acceptable in a soft RTOS. The chief design goal is not high throughput, but rather a guarantee of a soft or hard performance category. An RTOS that can usually or generally meet a deadline is a soft real-time OS, but if it can meet a deadline deterministically it is a hard real-time OS. An RTOS has an advanced algorithm for scheduling. Scheduler flexibility enables a wider, computer-system orchestration of process priorities, but a real-time OS is more frequently dedicated to a narrow set of applications. Key factors in a real-time OS are minimal interrupt latency and minimal thread switching latency; a real-time OS is valued more for how quickly or how predictably it can respond than for the amount of work it can perform in a given period of time. See the comparison of real-time operating systems for a comprehensive list. Also, see the list of operating systems for all types of operating systems. Design philosophies An RTOS is an operating system in which the time taken to process an input stimulus is less than the time lapsed until the next input stimulus of the same type. The most common designs are: Event-driven – switches tasks only when an event of higher priority needs servicing; called preemptive priority, or priority scheduling. Time-sharing – switches tasks on a regular clocked interrupt, and on events; called round robin. Time sharing designs switch tasks more often than strictly needed, but give smoother multitasking, giving the illusion that a process or user has sole use of a machine. Early CPU designs needed many cycles to switch tasks during which the CPU could do nothing else useful. Because switching took so long, early OSes tried to minimize wasting CPU time by avoiding unnecessary task switching. Scheduling In typical designs, a task has three states: Running (executing on the CPU); Ready (ready to be executed); Blocked (waiting for an event, I/O for example). Most tasks are blocked or ready most of the time because generally only one task can run at a time per CPU. The number of items in the ready queue can vary greatly, depending on the number of tasks the system needs to perform and the type of scheduler that the system uses. On simpler non-preemptive but still multitasking systems, a task has to give up its time on the CPU to other tasks, which can cause the ready queue to have a greater number of overall tasks in the ready to be executed state (resource starvation). Usually, the data structure of the ready list in the scheduler is designed to minimize the worst-case length of time spent in the scheduler's critical section, during which preemption is inhibited, and, in some cases, all interrupts are disabled, but the choice of data structure depends also on the maximum number of tasks that can be on the ready list. If there are never more than a few tasks on the ready list, then a doubly linked list of ready tasks is likely optimal. If the ready list usually contains only a few tasks but occasionally contains more, then the list should be sorted by priority. That way, finding the highest priority task to run does not require iterating through the entire list. Inserting a task then requires walking the ready list until reaching either the end of the list, or a task of lower priority than that of the task being inserted. Care must be taken not to inhibit preemption during this search. Longer critical sections should be divided into small pieces. If an interrupt occurs that makes a high priority task ready during the insertion of a low priority task, that high priority task can be inserted and run immediately before the low priority task is inserted. The critical response time, sometimes called the flyback time, is the time it takes to queue a new ready task and restore the state of the highest priority task to running. In a well-designed RTOS, readying a new task will take 3 to 20 instructions per ready-queue entry, and restoration of the highest-priority ready task will take 5 to 30 instructions. In more advanced systems, real-time tasks share computing resources with many non-real-time tasks, and the ready list can be arbitrarily long. In such systems, a scheduler ready list implemented as a linked list would be inadequate. Algorithms Some commonly used RTOS scheduling algorithms are: Cooperative scheduling Preemptive scheduling Rate-monotonic scheduling Round-robin scheduling Fixed priority pre-emptive scheduling, an implementation of preemptive time slicing Fixed-Priority Scheduling with Deferred Preemption Fixed-Priority Non-preemptive Scheduling Critical section preemptive scheduling Static time scheduling Earliest Deadline First approach Stochastic digraphs with multi-threaded graph traversal Intertask communication and resource sharing A multitasking operating system like Unix is poor at real-time tasks. The scheduler gives the highest priority to jobs with the lowest demand on the computer, so there is no way to ensure that a time-critical job will have access to enough resources. Multitasking systems must manage sharing data and hardware resources among multiple tasks. It is usually unsafe for two tasks to access the same specific data or hardware resource simultaneously. There are three common approaches to resolve this problem: Temporarily masking/disabling interrupts General-purpose operating systems usually do not allow user programs to mask (disable) interrupts, because the user program could control the CPU for as long as it wishes. Some modern CPUs do not allow user mode code to disable interrupts as such control is considered a key operating system resource. Many embedded systems and RTOSs, however, allow the application itself to run in kernel mode for greater system call efficiency and also to permit the application to have greater control of the operating environment without requiring OS intervention. On single-processor systems, an application running in kernel mode and masking interrupts is the lowest overhead method to prevent simultaneous access to a shared resource. While interrupts are masked and the current task does not make a blocking OS call, the current task has exclusive use of the CPU since no other task or interrupt can take control, so the critical section is protected. When the task exits its critical section, it must unmask interrupts; pending interrupts, if any, will then execute. Temporarily masking interrupts should only be done when the longest path through the critical section is shorter than the desired maximum interrupt latency. Typically this method of protection is used only when the critical section is just a few instructions and contains no loops. This method is ideal for protecting hardware bit-mapped registers when the bits are controlled by different tasks. Mutexes When the shared resource must be reserved without blocking all other tasks (such as waiting for Flash memory to be written), it is better to use mechanisms also available on general-purpose operating systems, such as a mutex and OS-supervised interprocess messaging. Such mechanisms involve system calls, and usually invoke the OS's dispatcher code on exit, so they typically take hundreds of CPU instructions to execute, while masking interrupts may take as few as one instruction on some processors. A (non-recursive) mutex is either locked or unlocked. When a task has locked the mutex, all other tasks must wait for the mutex to be unlocked by its owner - the original thread. A task may set a timeout on its wait for a mutex. There are several well-known problems with mutex based designs such as priority inversion and deadlocks. In priority inversion a high priority task waits because a low priority task has a mutex, but the lower priority task is not given CPU time to finish its work. A typical solution is to have the task that owns a mutex 'inherit' the priority of the highest waiting task. But this simple approach gets more complex when there are multiple levels of waiting: task A waits for a mutex locked by task B, which waits for a mutex locked by task C. Handling multiple levels of inheritance causes other code to run in high priority context and thus can cause starvation of medium-priority threads. In a deadlock, two or more tasks lock mutex without timeouts and then wait forever for the other task's mutex, creating a cyclic dependency. The simplest deadlock scenario occurs when two tasks alternately lock two mutex, but in the opposite order. Deadlock is prevented by careful design. Message passing The other approach to resource sharing is for tasks to send messages in an organized message passing scheme. In this paradigm, the resource is managed directly by only one task. When another task wants to interrogate or manipulate the resource, it sends a message to the managing task. Although their real-time behavior is less crisp than semaphore systems, simple message-based systems avoid most protocol deadlock hazards, and are generally better-behaved than semaphore systems. However, problems like those of semaphores are possible. Priority inversion can occur when a task is working on a low-priority message and ignores a higher-priority message (or a message originating indirectly from a high priority task) in its incoming message queue. Protocol deadlocks can occur when two or more tasks wait for each other to send response messages. Interrupt handlers and the scheduler Since an interrupt handler blocks the highest priority task from running, and since real-time operating systems are designed to keep thread latency to a minimum, interrupt handlers are typically kept as short as possible. The interrupt handler defers all interaction with the hardware if possible; typically all that is necessary is to acknowledge or disable the interrupt (so that it won't occur again when the interrupt handler returns) and notify a task that work needs to be done. This can be done by unblocking a driver task through releasing a semaphore, setting a flag or sending a message. A scheduler often provides the ability to unblock a task from interrupt handler context. An OS maintains catalogues of objects it manages such as threads, mutexes, memory, and so on. Updates to this catalogue must be strictly controlled. For this reason, it can be problematic when an interrupt handler calls an OS function while the application is in the act of also doing so. The OS function called from an interrupt handler could find the object database to be in an inconsistent state because of the application's update. There are two major approaches to deal with this problem: the unified architecture and the segmented architecture. RTOSs implementing the unified architecture solve the problem by simply disabling interrupts while the internal catalogue is updated. The downside of this is that interrupt latency increases, potentially losing interrupts. The segmented architecture does not make direct OS calls but delegates the OS related work to a separate handler. This handler runs at a higher priority than any thread but lower than the interrupt handlers. The advantage of this architecture is that it adds very few cycles to interrupt latency. As a result, OSes which implement the segmented architecture are more predictable and can deal with higher interrupt rates compared to the unified architecture. Similarly, the System Management Mode on x86 compatible Hardware can take a lot of time before it returns control to the operating system. Memory allocation Memory allocation is more critical in a real-time operating system than in other operating systems. First, for stability there cannot be memory leaks (memory that is allocated but not freed after use). The device should work indefinitely, without ever needing a reboot. For this reason, dynamic memory allocation is frowned upon. Whenever possible, all required memory allocation is specified statically at compile time. Another reason to avoid dynamic memory allocation is memory fragmentation. With frequent allocation and releasing of small chunks of memory, a situation may occur where available memory is divided into several sections and the RTOS is incapable of allocating a large enough continuous block of memory, although there is enough free memory. Secondly, speed of allocation is important. A standard memory allocation scheme scans a linked list of indeterminate length to find a suitable free memory block, which is unacceptable in an RTOS since memory allocation has to occur within a certain amount of time. Because mechanical disks have much longer and more unpredictable response times, swapping to disk files is not used for the same reasons as RAM allocation discussed above. The simple fixed-size-blocks algorithm works quite well for simple embedded systems because of its low overhead. See also Adaptive Partition Scheduler Comparison of real-time operating systems Data General RDOS DO-178B Earliest deadline first scheduling Firmware FreeRTOS Interruptible operating system Least slack time scheduling OSEK POSIX Rate-monotonic scheduling Robot Operating System SCADA Synchronous programming language Time-triggered system Time-utility function References Operating systems Real-time computing

Operating System (OS)

EROS (microkernel) Extremely Reliable Operating System (EROS) is an operating system developed starting in 1991 at the University of Pennsylvania, and then Johns Hopkins University, and The EROS Group, LLC. Features include automatic data and process persistence, some preliminary real-time support, and capability-based security. EROS is purely a research operating system, and was never deployed in real world use. , development stopped in favor of two successor systems, CapROS and Coyotos. Key concepts The overriding goal of the EROS system (and its relatives) is to provide strong support at the operating system level for the efficient restructuring of critical applications into small communicating components. Each component can communicate with the others only through protected interfaces, and is isolated from the rest of the system. A protected interface, in this context, is one that is enforced by the lowest level part of the operating system, the kernel. That is the only part of the system that can move information from one process to another. It also has complete control of the machine and (if properly constructed) cannot be bypassed. In EROS, the kernel-provided mechanism by which one component names and invokes the services of another is a capability, using inter-process communication (IPC). By enforcing capability-protected interfaces, the kernel ensures that all communications to a process arrive via an intentionally exported interface. It also ensures that no invocation is possible unless the invoking component holds a valid capability to the invokee. Protection in capability systems is achieved by restricting the propagation of capabilities from one component to another, often through a security policy termed confinement. Capability systems naturally promote component-based software structure. This organizational approach is similar to the programming language concept of object-oriented programming, but occurs at larger granularity and does not include the concept of inheritance. When software is restructured in this way, several benefits emerge: The individual components are most naturally structured as event loops. Examples of systems that are commonly structured this way include aircraft flight control systems (see also DO-178B Software Considerations in Airborne Systems and Equipment Certification), and telephone switching systems (see 5ESS switch). Event-driven programming is chosen for these systems mainly because of simplicity and robustness, which are essential attributes in life-critical and mission-critical systems. Components become smaller and individually testable, which helps to more readily isolate and identify flaws and bugs. The isolation of each component from the others limits the scope of any damage that may occur when something goes wrong or the software misbehaves. Collectively, these benefits lead to measurably more robust and secure systems. The Plessey System 250 was a system originally designed for use in telephony switches, which capability-based design was chosen specifically for reasons of robustness. In contrast to many earlier systems, capabilities are the only mechanism for naming and using resources in EROS, making it what is sometimes referred to as a pure capability system. In contrast, IBM i is an example of a commercially successful capability system, but it is not a pure capability system. Pure capability architectures are supported by well-tested and mature mathematical security models. These have been used to formally demonstrate that capability-based systems can be made secure if implemented correctly. The so-called "safety property" has been shown to be decidable for pure capability systems (see Lipton). Confinement, which is the fundamental building block of isolation, has been formally verified to be enforceable by pure capability systems, and is reduced to practical implementation by the EROS constructor and the KeyKOS factory. No comparable verification exists for any other primitive protection mechanism. There is a fundamental result in the literature showing that safety is mathematically undecidable in the general case (see HRU, but note that it is of course provable for an unbounded set of restricted cases). Of greater practical importance, safety has been shown to be false for all of the primitive protection mechanisms shipping in current commodity operating systems. Safety is a necessary precondition to successful enforcement of any security policy. In practical terms, this result means that it is not possible in principle to secure current commodity systems, but it is potentially possible to secure capability-based systems provided they are implemented with sufficient care. Neither EROS nor KeyKOS has ever been successfully penetrated, and their isolation mechanisms have never been successfully defeated by any inside attacker, but it is not known whether the two implementations were careful enough. One goal of the Coyotos project is to demonstrate that component isolation and security has been definitively achieved by applying software verification techniques. The L4.sec system, which is a successor to the L4 microkernel family, is a capability-based system, and has been significantly influenced by the results of the EROS project. The influence is mutual, since the EROS work on high-performance invocation was motivated strongly by Jochen Liedtke's successes with the L4 microkernel family. History The primary developer of EROS was Jonathan S. Shapiro. He is also the driving force behind Coyotos, which is an "evolutionary step" beyond the EROS operating system. The EROS project started in 1991 as a clean-room reconstruction of an earlier operating system, KeyKOS. KeyKOS was developed by Key Logic, Inc., and was a direct continuation of work on the earlier Great New Operating System In the Sky (GNOSIS) system created by Tymshare, Inc. The circumstances surrounding Key Logic's demise in 1991 made licensing KeyKOS impractical. Since KeyKOS did not run on popular commodity processors in any case, the decision was made to reconstruct it from the publicly available documentation. By late 1992, it had become clear that processor architecture had changed significantly since the introduction of the capability idea, and it was no longer obvious that component-structured systems were practical. Microkernel-based systems, which similarly favor large numbers of processes and IPC, were facing severe performance challenges, and it was uncertain if these could be successfully resolved. The x86 architecture was clearly emerging as the dominant architecture but the expensive user/supervisor transition latency on the 386 and 486 presented serious challenges for process-based isolation. The EROS project was turning into a research effort, and moved to the University of Pennsylvania to become the focus of Shapiro's dissertation research. By 1999, a high performance implementation for the Pentium processor had been demonstrated that was directly performance competitive with the L4 microkernel family, which is known for its exceptional speed in IPC. The EROS confinement mechanism had been formally verified, in the process creating a general formal model for secure capability systems. In 2000, Shapiro joined the faculty of Computer Science at Johns Hopkins University. At Hopkins, the goal was to show how to use the facilities provided by the EROS kernel to construct secure and defensible servers at application level. Funded by the Defense Advanced Research Projects Agency and the Air Force Research Laboratory, EROS was used as the basis for a trusted window system, a high-performance, defensible network stack, and the beginnings of a secure web browser. It was also used to explore the effectiveness of lightweight static checking. In 2003, some very challenging security issues were discovered that are intrinsic to any system architecture based on synchronous IPC primitives (notably including EROS and L4). Work on EROS halted in favor of Coyotos, which resolves these issues. , EROS and its successors are the only widely available capability systems that run on commodity hardware. Status Work on EROS by the original group has halted, but there are two successor systems. The CapROS system is building directly from the EROS code base, while the Coyotos system is a successor system that addresses some of the architectural deficiencies of EROS, and is exploring the possibility of a fully verified operating system. Both CapROS and Coyotos are expected to be released in various commercial deployments. See also Nanokernel References Journals External links Coyotos home page at the Wayback Machine (archived September 2, 2016) Jonathan Shapiro's homepage CapROS Microkernels Real-time operating systems Capability systems

Operating System (OS)

CentOS CentOS (, from Community Enterprise Operating System; also known as CentOS Linux) is a Linux distribution that provides a free and open-source community-supported computing platform, functionally compatible with its upstream source, Red Hat Enterprise Linux (RHEL). In January 2014, CentOS announced the official joining with Red Hat while staying independent from RHEL, under a new CentOS governing board. The first CentOS release in May 2004, numbered as CentOS version 2, was forked from RHEL version 2.1AS. Since version 8, CentOS officially supports the x86-64, ARM64, and POWER8 architectures, and releases up to version 6 also supported the IA-32 architecture. , AltArch releases of CentOS 7 are available for the IA-32 architecture, Power ISA, and for the ARMv7hl and AArch64 variants of the ARM architecture. CentOS 8 was released on 24 September 2019. In December 2020, Red Hat unilaterally terminated CentOS development. In response, CentOS founder Gregory Kurtzer created the Rocky Linux project as a successor to the original mission of CentOS. In March 2021, Cloud Linux (makers of CloudLinux OS) released a new RHEL derivative called AlmaLinux. While the distribution was discontinued at the end of 2021, development of CentOS Stream, its midstream variant, continues. History CentOS originated as a build of CAOS Linux, an RPM-based Linux distribution started by Gregory Kurtzer in 2002. Infiscale described its GravityOS as "[including] the small footprint of Caos", indicating a certain level of influence from the discontinued distribution. In June 2006, David Parsley, the primary developer of Tao Linux (another RHEL clone), announced the retirement of Tao Linux and its rolling into CentOS development. Tao users migrated to the CentOS release via . In July 2009, it was reported in an open letter on the CentOS Project web site that CentOS's founder, Lance Davis, had disappeared in 2008. Davis had ceased contribution to the project, but continued to hold the registration for the CentOS domain and PayPal account. In August 2009, the CentOS team reportedly made contact with Davis and obtained the centos.info and centos.org domains. In July 2010, CentOS overtook Debian to become the most popular Linux distribution for web servers, with almost 30% of all Linux web servers using it. Debian retook the lead in January 2012. In January 2014, Red Hat announced that it would sponsor the CentOS Project, "helping to establish a platform well-suited to the needs of open source developers that integrate technologies in and around the operating system". As a result of these changes, ownership of CentOS trademarks was transferred to Red Hat, which now employs most of the CentOS head developers; however, they work as part of Red Hat's Open Source and Standards team, which operates separately from the Red Hat Enterprise Linux team. A new CentOS governing board was also established. On 8 December 2020, the CentOS Project announced that the distribution would be discontinued at the end of 2021 in order to focus on CentOS Stream. The community's response to this announcement was overwhelmingly negative. Soon thereafter, CentOS founder, Gregory Kurtzer announced a new project to continue the original CentOS focus, which became known as Rocky Linux. CloudLinux created AlmaLinux to provide a community-supported successor to CentOS Linux, aiming for binary-compatibility with the current version of RHEL. A beta version of AlmaLinux was first released on February 1, 2021, and the first stable release of AlmaLinux was published on March 30, 2021. Design CentOS developers use Red Hat's source code to create a final product very similar to RHEL. Red Hat's branding and logos are changed because Red Hat does not allow them to be redistributed. CentOS is available free of charge. Technical support is primarily provided by the community via official mailing lists, web forums, and chat rooms. The project is affiliated with Red Hat but aspires to be more public, open, and inclusive. While Red Hat employs most of the CentOS head developers, the CentOS Project itself relies on donations from users and organizational sponsors. Versioning and releases CentOS releases CentOS version numbers for releases older than 7.0 have two parts, a major version and a minor version, which correspond to the major version and update set of Red Hat Enterprise Linux (RHEL) used to build a particular CentOS release. For example, CentOS 6.5 is built from the source packages of RHEL 6 update 5 (also known as RHEL version 6.5), which is a so-called "point release" of RHEL 6. Starting with version 7.0, CentOS version numbers also include a third part that indicates the monthstamp of the source code the release is based on. For example, version number 7.0-1406 still maps this CentOS release to the zeroth update set of RHEL 7, while "1406" indicates that the source code this release is based on dates from June 2014. Using the monthstamp allows installation images to be reissued for () oncoming container and cloud releases, while maintaining a connection to the related base release version. Since mid-2006 and starting with RHEL version 4.4, which is formally known as Red Hat Enterprise Linux 4.0 update 4, Red Hat has adopted a version-naming convention identical to that used by CentOS (for example, RHEL 4.5 or RHEL 6.5). On 10 September 2019 CentOS deferred CentOS 8.1 work for CentOS 7.7 since CentOS 7.x was in production and CentOS 8.x was not in production. Once CentOS 7.7 was released resources moved back to CentOS 8.0. On 24 September 2019 CentOS officially released CentOS version 8.0. End-of-support schedule According to the Red Hat Enterprise Linux (RHEL) life cycle, CentOS 5, 6 and 7 will be "maintained for up to 10 years" as it is based on RHEL. Previously, CentOS 4 had been supported for seven years. Older version information CentOS version 7 Latest version information CentOS version 8 AltArch releases AltArch releases are released by the Alternative Architecture Special Interest Group (AltArch SIG) to support architectures that are not supported by the base CentOS releases. Add-ons releases Software Collections (SCL) is a CentOS repository that provides a set of programming languages, database servers, and various related packages. Provided software versions are either more recent than their equivalent versions included in the base CentOS distribution, or are made available as official CentOS packages for the first time. (See also the list of CentOS repositories below.) Packages available from the SCL do not replace the default system tools provided with CentOS. Instead, a parallel set of tools is installed in the directory, and can be optionally enabled per application by using supplied utility. For example, the default versions of Perl or MySQL remain those provided by the base CentOS installation. Releases without upstream equivalents Some of the ISO images released by the CentOS Project have no direct upstream equivalents. They are created for specific purposes, such as for providing a live bootable image, or for providing a reduced-size installation medium. In addition to those listed below, there are also AltArch releases, which also have no direct upstream equivalents. LiveCD and LiveDVD images contain a bootable compressed file system, created by a set of custom scripts using a kickstart configuration file. These live images can be also installed to hard disk, thus obtaining a fully functional CentOS installation. The set of packages installed that way on a hard disk can not be adjusted during the installation, as that is a simple transfer of the image existing on CD/DVD, to a hard disk. After booting from hard disk, yum can be used for adding or removing packages. MinimalCD images contain a minimum of packages required for a functional installation, with no compromises in security or network usability. These minimal images use the standard CentOS installer with all of its regular features minus the selection of packages. Yum can be used after the installation is completed to add or remove packages. Special interest groups Special interest groups (SIGs) are organized portions of the CentOS community that open paths for building specialized variants of CentOS, which fulfill specific sets of requirements. SIGs have the freedom to modify and enhance CentOS in various ways, including adding more cutting-edge software, rebuilding existing packages depending on the requirements, providing alternative desktop environments, or making CentOS available on otherwise unsupported architectures. Architectures As of version 8, CentOS fully supports x86-64, POWER8 and 64-bit ARM architectures, while the following architectures are not supported: IA-32 in all variants, not supported since CentOS 7 IA-32 without Physical Address Extension (PAE), not supported since CentOS 6 IA-64 (Intel Itanium architecture), was supported in CentOS 3 and 4 32-bit PowerPC (Apple Macintosh and PowerMac running the G3 or G4 PowerPC processor), beta support was available in CentOS 4 IBM Mainframe (eServer zSeries and S/390), not supported since CentOS 5 Alpha, support was available in CentOS 4 SPARC, beta support was available in CentOS 4 , AltArch releases of CentOS 7 are available for the ARMv7hl and AArch64 variants of the ARM architecture, and plans exist for supporting other variants of the ARM architecture. ARM support is a community effort coordinated through the AltArch SIG. AltArch releases of CentOS 7 are also available for the IA-32 architecture and Power ISA (POWER7 and POWER8 chips). A Live CD version of CentOS is available at mirror.centos.org. A bootable Live USB image of CentOS can be created manually or with UNetbootin. CentOS images are also available on Amazon's EC2 cloud, in form of prebuilt and already published Amazon Machine Images (AMIs). Repositories There are three primary CentOS repositories (also known as channels), containing software packages that make up the main CentOS distribution: base : contains packages that form CentOS point releases, and gets updated when the actual point release is formally made available in form of ISO images. updates : contains packages that serve as security, bugfix or enhancement updates, issued between the regular update sets for point releases. Bugfix and enhancement updates released this way are only those unsuitable to be released through the CentOS-Fasttrack repository described below. addons : provides packages required for building the packages that make up the main CentOS distribution, but are not provided by the upstream. The CentOS Project provides several additional repositories that contain software packages not provided by the default base and updates repositories. Those repositories include the following: CentOS Extras : contains packages that provide additional functionality to CentOS without breaking its upstream compatibility or updating the base components. CentOSPlus : contains packages that actually upgrade certain base CentOS components, changing CentOS so that it is not exactly like the upstream provider's content. CentOS-Testing : serves as a proving ground for packages on their way to CentOSPlus and CentOS Extras. Offered packages may or may not replace core CentOS packages, and are not guaranteed to work properly. CentOS-Fasttrack : contains bugfix and enhancement updates issued from time to time, between the regular update sets for point releases. The packages released this way serve as close candidates for the inclusion into the next point release. This repository does not provide security updates, and does not contain packages unsuitable for uncertain inclusion into point releases. CR (Continuous Release) : makes generally available packages that will appear in the next point release of CentOS. The packages are made available on a testing and hotfix basis, until the actual point release is formally released in form of ISO images. debuginfo : Contains packages with debugging symbols generated when the primary packages were built. contrib : Contains packages contributed by CentOS users that do not overlap with any of the core distribution packages. Software Collections : Provides versions of software newer than those provided by the base distribution, see above for more details. CentOS Stream CentOS Stream is a midstream Linux distribution situated between the upstream development in Fedora and the downstream development for RHEL. The initial release, CentOS Stream 8, was released on 24 September 2019, at the same time as CentOS 8, followed by CentOS Stream 9 on 3 December 2021. Notes References Further reading External links Archived official website of CAOS Linux (19 June 2012) Enterprise Linux distributions IA-32 Linux distributions RPM-based Linux distributions X86-64 Linux distributions Power ISA Linux distributions ARM Linux distributions Linux distributions

Operating System (OS)

Cosmos (operating system) C# Open Source Managed Operating System (Cosmos) is a toolkit for building operating systems, written mostly in the programming language C# and small amounts of a high level assembly language named X#. Cosmos is a backronym, in that the acronym was chosen before the meaning. It is open-source software released under a BSD license. Cosmos encompasses an ahead-of-time (AOT) compiler named IL2CPU to translate Common Intermediate Language (CIL) into native instructions. Cosmos compiles user-made programs and associated libraries using IL2CPU to create a bootable native executable that can be run with no support. The resulting output can be booted from a USB flash drive, CD-ROM, over a network via Preboot Execution Environment (PXE), or inside a virtual machine. Recent releases also allow deploying to certain x86 embedded devices over Universal Serial Bus (USB). While C# is the primary language used by developers (both on the backend and by end users of Cosmos), many CLI languages can be used, provided they compile to pure CIL without the use of Platform Invocation Services (P/Invokes). Cosmos is mainly intended for use with .NET Core. , Cosmos does not aim to become a full operating system, but rather a toolkit to allow other developers to simply and easily build their own operating systems using .NET Core. It also functions as an abstraction layer, hiding much of the inner workings of the hardware from the eventual developer. Older versions of Cosmos were released in Milestones, with the last being Milestone 5 (released August 2010). More recently, the project switched to simply naming new releases after the latest commit number. Releases of Cosmos are divided into two types: the Userkit, and the Devkit. The Userkit is a pre-packaged release that is updated irregularly, as new and improved features are added. Userkits are generally considered stable, but do not include recent changes and may lack features. The Devkit refers to the source code of Cosmos and must be built manually. The Devkits are usually somewhat stable, but they may have some bugs. The Devkit can be acquired on GitHub and uses Git as the source control management. Most work on Cosmos is currently aimed at improving debugger functionality and Microsoft Visual Studio integration. Kernel work is focused on implementing file systems, memory management, and developing a reliable network interface. Syslinux serves as the project's bootloader. Developing with Cosmos Cosmos has many facilities to improve the experience of developing operating systems with it, designed to make the process as fast and painless as possible, knowledge of the assembly language is not required to use Cosmos. Visual Studio integration A key feature of Cosmos, which separates it from other operating systems of its type, is its tight integration with Microsoft Visual Studio. Code can be written, compiled, debugged, and run entirely through Visual Studio, with only a few key presses. Cosmos no longer supports Visual Studio 2015 or Visual Studio 2017, now it only supports Visual Studio 2019. Debugging Cosmos can be seamlessly debugged through Visual Studio when running over PXE or in a virtual machine. Many standard debugging features are present, such as breakpoints, tracing, and logging. Also, debugging can be done via serial cables, if running on physical hardware. When running in VMWare, Cosmos supports stepping and breakpoints, even while an operating system is running. Running Cosmos uses virtualization to help speed development by allowing developers to test their operating systems without having to restart their computers as often. By default, VMWare Player is used, due to its ease of use in terms of integration with the project. Other virtualization environments are supported as well, such as Bochs and VirtualPC. An ISO disk image may also be generated that can be burned to a USB flash drive, CD-ROM, or similar media. PXE booting is also supported, allowing for remote machines to run Cosmos over a network connection. Compile process IL2CPU To compile .NET CIL into assembly language, Cosmos developers created an ahead-of-time compiler named IL2CPU, designed to parse CIL and output x86 opcodes. (IL To CPU) is an AOT compiler that is written using a Common Intermediate Language compliant language (C#). It translates Common Intermediate Language to machine code. X# X# is a low-level programming language developed for the x86 processor architecture as a part of Cosmos operating system to make operating system development easier. X# is designed to bring some of C-like language syntax to assembly language. In the beginning, X# was an aid for debugging services of Cosmos. The X# compiler is an open source command-line interface (console) program with an atypical architecture. It parses lines of code into tokens and compares them with patterns. Finally, matched X# code patterns are translated to intel syntax x86 assembly, usually for the Netwide Assembler (NASM). In first versions, X# operation was mostly 1:1 with assembly code, but hasn't been, which is the reason why the X# compiler was written. Syntax The syntax of X# is simple. Despite being similar to C, X# syntax differs and is stricter. Comments X# supports only one kind of comment, the C++-style single line comment, started with a double forward slash - //. Constants X# supports the definition of named constants which are declared outside of functions. Defining a numeric constant is similar to C++; for example: const i = 0. Referencing the constant elsewhere requires a # before the name; for example: - "#i". To define a string constant, single quotes ('') are used. To use a single quote in a string constant, it must be escaped by placing a backslash before it, as 'I\'m so happy'. X# strings are null terminated. Hexadecimal constants are prefixed with a dollar sign ($), followed by the constant. ($B8000). Decimal constants are not decorated but may not start with 0. Binary and octal constants aren't supported yet. Labels Labels in X# are mostly equivalent to labels in other assembly languages. The instruction to jump to a label uses the goto mnemonic, as opposed to the conventional jump or jmp mnemonic. CodeLabel1: goto CodeLabel2: Namespaces X# program files must begin with a namespace directive. X# lacks a namespace hierarchy, so any directive will change the current namespace until it's changed again or the file ends. Variables or constants in different namespaces may have the same name as the namespace is prefixed to the member's name on assembly output. Namespaces cannot reference each other except through "cheats" using native-assembly-level operations. namespace FIRST // Everything variable or constant name will be prefixed with FIRST and an underscore. Hence the true full name of the below variable // is FIRST_aVar. var aVar namespace SECOND // It's not a problem to name another variable aVar. Its true name is SECOND_aVar. var aVar namespace FIRST // This code is now back to the FIRST namespace until the file ends. Functions All X# executive code should be placed in functions defined by the 'function' keyword. Unlike C, X# does not support any formal parameter declaration in the header of the functions, so the conventional parentheses after the function name are omitted. Because line-fixed patterns are specified in syntax implemented in code parser, the opening curly bracket can't be placed on the next line, unlike in many other C-style languages. function xSharpFunction { // function code } Because X# is a low-level language, there are no stack frames inserted, so by default, there should be the return EIP address on the top of the stack. X# function calls do contain arguments enclosed in parentheses, unlike in function headers. Arguments passed to functions can be registers, addresses, or constants. These arguments are pushed onto the stack in reverse order. Note that the stack on x86 platforms cannot push or pop one-byte registers. function xSharpFunction { EAX = $10 anotherFunction(EAX); return } function anotherFunction { //function code } The return keyword returns execution to the return EIP address saved in the stack. Arithmetic and bitwise operations X# can work with three low-level data structures: the registers, the stack and the memory, on different ports. The registers are the base of all normal operations for X#. A register can be copied to another by writing DST = SRC as opposed to mov or load/store instructions. Registers can be incremented or decremented just as easily. Arithmetic operations (add, subtract, multiply, divide) are written as dest op src where src is a constant, variable, or register, and dest is both an operand and the location where the result is stored. Examples of assignment and arithmetic operations are shown below. ESI = 12345 // assign 12345 to ESI EDX = #constantForEDX // assign #ConstantForEDX to EDX EAX = EBX // move EBX to EAX => mov eax, ebx EAX-- // decrement EAX => dec eax EAX++ // increment EAX => inc eax EAX + 2 // add 2 to eax => add eax, 2 EAX - $80 // subtract 0x80 from eax => sub eax, 0x80 BX * CX // multiply BX by CX => mul cx -- division, multiplication and modulo should preserve registers CX / BX // divide CX by BX => div bx CX mod BX // remainder of CX/BX to BX => div bx Register shifting and rolling is similar to C. DX << 10 // shift left by 10 bits CX >> 8 // shift right by 8 bits EAX <~ 6 // rotate left by 6 bits EAX ~> 4 // rotate right by 4 bits Other bitwise operations are similar to arithmetic operations. DL & $08 // perform bitwise AND on DL with 0x08 and store the result in DL CX | 1 // set the lowest bit of CX to 1 (make it odd) EAX = ~ECX // perform bitwise NOT on ECX and store the result in EAX EAX ^ EAX // erase EAX by XORing it with itself Stack Stack manipulation in X# is performed using + and - prefixes, where + pushes a register, value, constant or all registers onto the stack and - pops a value to some register. All constants are pushed on stack as double words, unless stated otherwise (pushing single bytes is not supported). +ESI // push esi -EDI // pop into edi +All // save all registers => pushad -All // load all registers => popad +$1badboo2 // push 0x1badboo2 on the stack +$cafe as word // \/ +$babe as word // push 0xcafebabe +#VideoMemory // push value of constant VideoMemory Variables Variables are defined within namespaces (as there are no stack frames, local variables aren't supported) using the var keyword. Arrays can be defined by adding the array's type and size on the end of the declaration. Variables and arrays are zeroed by default. To reference a variable's value, it must be prefixed with a dot. Prefixing that with an @ will reference the variable's address. namespace XSharpVariables var zeroVar // variable will be assigned zero var myVar1 = $f000beef // variable will be assigned 0xf000beef var someString = 'Hello XSharp!' // variable will be assigned 'Hello XSharp!\0', var buffer byte[1024] // variable of size 1024 bytes will be assigned 1024 zero bytes ... EAX = .myVar1 // moves value of myVar1 (0xf000beef) to EAX ESI = @.someString // moves address of someString to ESI CL = .someString // moves first character of someString ('H') to CL .zeroVar = EAX // assigns zeroVar to value of EAX X# can access an address with a specified offset using square brackets: var someString = 'Hello XSharp!' //variable will be assigned to 'Hello XSharp!\0' ... ESI = @.someString // load address of someString to ESI CL = 'B' // set CL to 'B' (rewrite 'H' on the start) CH = ESI[1] // move second character ('E') from string to CH ESI[4] = $00 // end string //Value of someString will be 'Bell' (or 'Bell\0 XSharp!\0') Comparison There are two ways of comparing values: pure comparison and if-comparison. Pure comparison leaves the result in FLAGS so it can be used in native assembly or using the if keyword without specifying comparison members. If comparison compares two members directly after an if keyword. Here are two ways of writing a (slow) X# string length (strlen)function: // Method 1: using pure comparison function strlen { ESI = ESP[4] // get pointer to string passed as first argument ECX ^ ECX // clear ECX Loop: AL = ESI[ECX]// get next character AL ?= 0 // is it 0? save to FLAGS if = return // if ZF is set, return ECX++ // else increment ECX goto Loop // loop... //Way 2: using if function strlen { ESI = ESP[4] // get pointer to string passed as first argument ECX ^ ECX // clear ECX Loop: AL = ESI[ECX] if AL = 0 return// AL = 0? return ECX++ goto Loop // loop.... } There are six available comparison operators: < > = <= >= !=. These operators can be used in both comparisons and loops. Note that there's also a bitwise AND operator which tests bits: AL ?& $80 // test AL MSB if = return // if ZF is 0, test instruction resulted in 0 and MSB is not set. Writing Cosmos code An operating system built with Cosmos is developed in a similar fashion to any .NET C# console program. Additional references are made in the start of the program which give access to the Cosmos libraries. These libraries override the system libraries normally used in C# console programs since the resulting binary won't be running on an installation of Microsoft Windows. User Kit and Visual Studio The Cosmos User Kit is a part of Cosmos designed to make Cosmos easier to use for developers using Microsoft Visual Studio. When installed, the user kit adds a new project type to Visual Studio, called a Cosmos Project. This is a modified version of a console application, with the Cosmos compiler and bootup stub code already added. Compiling a project Once the code is complete, it may be compiled using .NET compiler. This converts the application from the original source code (C# or otherwise) into Common Intermediate Language (CIL), the native language of .NET Framework. Next the application is run, showing the Cosmos Builder Window, which presents the developer with options which determine exactly how the project is compiled. These options include how to boot the project - via emulators such as Quick Emulator (QEMU), Virtual PC, and VMWare, writing to a disk image (ISO) file that can later be written to a CD-ROM, or via Preboot Execution Environment (PXE) network booting - as well as debug options using Cosmos' built-in debugger, and other options. When the user has chosen their desired options, they press the Build button. This invokes the IL2CPU compiler which systematically scans through all of the applications CIL code (excluding the Cosmos compiler code), converting it into assembly language for the selected processor architecture. , only x86 is supported. Next, Cosmos invokes the selected assembler to convert this assembly language code into native central processing unit (CPU) opcode. Finally, the desired output option is activated, be this starting an emulator, starting a PXE engine, or producing an ISO disk image file from the binary code opcode. Debug options Cosmos offers several options as to how to deploy the resulting OS and how to debug the output. Virtualization Cosmos allows users to boot the operating system in an emulated environment using a virtual machine. This lets developers test the system on their own computer without having to reboot, giving the advantages of not requiring extra hardware or that developers exit their integrated development environment. Currently, only VMWare is supported. Bochs support is underway. QEMU and VirtualBox are not supported officially. Disk images This option writes the operating system to a disk image (ISO image) file, which can be loaded into some emulators (such as Bochs, QEMU or more commonly VMware) or written to a CD-ROM and booted on real hardware. This option also allows deploying to a USB mass storage device, such as a USB flash drive, to boot on devices that may not have an optical disc drive. Because networking is not in place yet, debugging is unsupported with this deploy option. PXE network boot This option allows the operating system to boot on real hardware. The data is sent via a local area network (LAN) to the client machine. This requires two computers: one as the client machine (on which the OS is booted) and one as the server (usually the development machine). It also requires a network connecting the two computers, a client machine with a network card, and a Basic Input/Output System (BIOS) that can PXE boot. , debugging over a network is unsupported. Cosmos assembler The Cosmos Project team have also created an assembler that is designed to eventually become the main assembler for the Cosmos system. However, the assembler is still inefficient and slow, and so the Netwide Assembler (NASM) is used instead. See also IL2CPU .NET Framework Mono (software) SharpOS Singularity (operating system) Phantom OS References External links Cosmos Overview article at CodeProject Cosmos Dev Yahoo Group Cosmos Fan Page on Facebook News coverage Mary Jo Foley on ZDNet - Cosmos: An open-source .Net-based microkernel OS is born Scott Hanselman: Tiny Managed Operating System Edition Embedded operating systems Operating system kernels Free software operating systems Beta software X86 operating systems .NET Software using the BSD license

Operating System (OS)

Unisys 2200 Series system architecture The figure shows a high-level architecture of the OS 2200 system identifying major hardware and software components. The majority of the Unisys software is included in the subsystems and applications area of the model. For example, the database managers are subsystems and the compilers are applications. System Basics The details of the system architecture are covered in Unisys publication 3850 7802 Instruction Processor Programming Reference Manual. Also see UNIVAC 1100/2200 series. The 1100 Series has used a 36-bit word with 6-bit characters since 1962. 36-bit computing was driven by a desire to process 10-digit positive and negative numbers. Also the military needed to be able to calculate accurate trajectories, design bridges, and perform other engineering and scientific calculations, they needed more than 32 bits of precision. A 32-bit floating point number only provided about 6 digits of accuracy while a 36 bit number provided the 8 digits of accuracy that were accepted as the minimum requirement. Since memory and storage space and costs drove the system, going to 64 bits was simply not acceptable in general. These systems use ones' complement arithmetic, which was not unusual at the time. Almost all computer manufacturers of the time delivered 36-bit systems with 6-bit characters including IBM, DEC, General Electric, and Sylvania. The 6-bit character set used by the 1100 Series is also a DoD mandated set. It was defined by the Army Signal Corps and called Fieldata (data returned from the field). The 1108 provided a 9-bit character format in order to support ASCII and later the ISO 8-bit sets, but they were not extensively used until the 1980s again because of space constraints. The 2200 Series architecture provides many registers. Base registers logically contain a virtual address that points to a word in a code or data bank (segment). They may point to the beginning of the bank or to any word within the bank. Index registers are used by instructions to modify the offset of the specified or assumed base register. Simple arithmetic (add, subtract) may be performed on all index registers. In addition, index registers consist of a lower offset portion and an upper increment portion. An instruction may both use the offset value in an index register as part of an address and specify that the increment is to be added to the offset. This allows loops to be accomplished with fewer instructions as incrementing the index by the step size can be accomplished without a separate instruction. Arithmetic registers allow the full set of computational instructions including all floating point operations. Some of those instructions work on adjacent pairs of registers to perform double-precision operations. There are no even-odd constraints. Any two registers may be used as a double-precision value. Four of the arithmetic registers are also index registers (the sets overlap – index register X12 is arithmetic register A0). This allows the full range of calculations to be performed on indexes without having to move the results. The rest of the registers, known as R registers, are used as fast temporary storage and for certain special functions. R1 holds the repeat count for those instructions that may be repeated (block transfer, execute repeated, etc.). R2 holds a bit mask for a few instructions that perform a bitwise logical operation in addition to some other functions (e.g., masked load upper) There are two full sets of registers (A, X, R, and B). One set, the user registers, is used by all applications and most portions of the operating system. It is saved and restored as part of activity (thread) state. The other set, the Exec registers, is used by interrupt processing routines and some other portions of the operating system that want to avoid having to save and restore user registers. The Exec registers are not writable by user applications although some user code can read them. As a result, the Exec is carefully designed never to leave private, secure, or confidential information in registers. Instruction interpretation chooses the appropriate register set to use based on a bit in the Processor State Register. This bit is always set (changed to privileged) on an interrupt. All registers are also visible in the address space, but the Exec portion is protected and a reference by non-privileged code will result in a fault interrupt. The 2200 Series uses a 36-bit segmented virtual address space. We’ll look later at the addressing architecture. The 2200 Series is a CISC architecture system. Not only are there a large number of instructions (current count is about 245) but many of them have addressing variants. Some of the variants are encoded directly in the instruction format (partial word references) and some are dependent on Processor State Register settings. Many instructions also perform very complex functions such as one that implements a large part of the COBOL EDIT verb. The above figure shows some of the building blocks of the architecture. "Data" and "COMM" are two of the primary examples of software subsystems that live in a protection ring between that of a user application and the Exec. There are many other such subsystems and users write their own. Memory and Addressing Level As was mentioned earlier the 2200 Series uses a 36-bit segmented virtual address. The original notion of a segmented space came from the earliest implementation that emphasized code and data separation for performance and the use of shared code banks. Over the years this expanded to provide greater flexibility of levels of sharing and far greater protection for security and reliability. Controlled access to shared data was also introduced. A virtual address consists of three parts. The high-order 3 bits define the sharing level. This is the heart of the entire addressing and protection scheme. Every thread has eight Bank Descriptor Tables (Segment Descriptor Tables in the industry) based on B16-B23. The tables are indexed by level – level 0 refers to the Bank Descriptor Table (BDT) based on B16, level 2 the BDT based on B18, etc. The level 0 and level 2 BDTs are common to all threads in the system. Every run (process) has its own level 4 BDT, and that BDT is common to all threads in the run. Every user thread has its own unshared level 6 BDT. Activity Each extended-mode activity (thread) always has six banks, segments, which are totally unique to it. One is the Return Control Stack which holds information about the calling structure including any security relevant privilege and state changes. It is not accessible by the thread except through the use of the CALL, RETURN, and similar instructions. This is a major part of the protection and reliability mechanism. Applications cannot cause bad effects by changing the return addresses or overwriting the return control stack. Another unique bank is the automatic storage bank (Activity Local Store stack). This is used by the compilers to hold local variables created within a block. It is also used to hold all parameter lists passed on a call. One of the checks made by the operating system both on its own behalf and when a call is made to a protected subsystem is to ensure that the operands are on the thread-local stack and that the thread has the right to access the memory region referenced by any parameters. Because the parameters are kept in thread-local space, there is no chance that some other thread may change them during or after validation. It is the responsibility of the called procedure to perform similar checks on any secondary parameters that may exist in shared space (i.e., the primary parameter points to a structure that contains pointers). The procedure is expected to copy any such pointers to its own local space before validating them and then to use only that internally held validated pointer. Activities may create additional segments up to the limit of the available address space (233 words = 8GW or about 36GB). This is a convenient way for multi-threaded applications to get large amounts of memory space knowing that it is totally thread-safe and that they are not taking any space away from the rest of what is available to the program. Each activity in a program has its own independent space meaning an application with say 100 activities is able to use over 800GW (>3TB) of virtual space. Basic-mode activities do not start out with any such banks as basic-mode programs are not aware of the virtual address space, but any calls to extended-mode subsystems will cause those banks to be created. Programs OS 2200 does not implement programs in exactly the same way that UNIX, Linux, and Windows implement processes, but that is the closest analogy. The most obvious difference is that OS 2200 only permits a single program per Run (Job, Session) to be executing at a time. A program may have hundreds of threads, but cannot spawn other programs to run concurrently. There are several banks at the Program level that contain a mixture of Run (job, session) information and program information. These are control structures for the operating system. They have no access or read-only access for the program. Programs may retrieve information from some of these structures for debugging purposes or to retrieve things like the user-id and terminal-id without the overhead of a system call. They cannot be written by the program. They contain things like the thread state save areas, file control blocks, and accounting information. The rest of the banks are used by the program. When a program object file is executed, the operating system obtains the bank information from the file and creates banks as needed and loads the bank initial state from the file. The simplest program has a single bank containing code and data. This is considered very bad form, but is permitted for compatibility with old applications. You can only create such an application with assembly language. The standard compilers create one or more code banks and one or more data banks. Normally the code banks are marked as read-only as a debugging and reliability aid. There are no security concerns either way. The program can only affect itself. Each program thus has its own address space distinct from all other programs in the system. Nothing a program can do can change the contents of any other program’s memory. The OS and shared subsystems are protected by other mechanisms which will be discussed later. Even read access is prohibited to OS and subsystem memory in almost all cases from code in a program. It is possible to create a shared subsystem which is generally readable, or even writable, by multiple programs, but it must be explicitly installed that way by a privileged system administrator. Programs are initially created with just the banks specified in the object file and with a single activity. They may use system calls to create additional banks within their own program level and additional activities. Subsystems The closest analogy to a shared subsystem is a .dll. A subsystem is much like a program in many respects except that it does not have any activities associated with it. Instead it is accessed by other programs and subsystems typically via a CALL instruction. In fact, a program is a subsystem plus one or more activities. Every activity belongs to a "home" subsystem which is the program that created it. This subsystem concept is important as an encapsulation of access rights and privilege. Within their home subsystem, activities typically share common access rights to code and data banks. Code banks in the home subsystem are usually read-only, or even execute-only if they contain no constant data, but all activities will have the right to execute them. Subsystems are also combinations of banks and may contain data banks as well as code banks. All globally shared subsystems must be installed in the system by someone with appropriate administrator privileges. Subsystems may also open files. The Database manager is a subsystem which opens all the database files for its use typically with exclusive access rights. The operating system will attach its own banks to a subsystem to hold the file control tables. OS The OS level contains the banks of the Exec. These banks are never directly accessible by either programs or global subsystems. Entry points to the OS are all handled in the same way as a protected subsystem. Calls made to the OS are always via "gates," instructions that exist for that purpose (ER = Executive Request), or via interrupts. The Bank Descriptor Index (BDI) The next part of the virtual address is the BDI or Bank Descriptor Index. The Level field selected a particular bank descriptor table base register (B16-B23). Base registers B16-B23 are part of the activity state and are maintained by the Exec with no direct access by the activity. The Bank Descriptor tables for the program and activity levels exist within the program-level banks that belong to the operating system. The BDI is simply an index into a Bank Descriptor Table. Each entry in the table contains information about a bank. Each such entry describes up to 1MB (256KW) of virtual address space. When a larger contiguous space is needed, consecutive entries are logically combined to create a larger bank up to the maximum of 230 words. The Bank Descriptor Table Entry (Bank Descriptor – BD) gives the size of the bank (small = up to 256KW, large = up to 16MW, very large = up to 1GW). A small bank is always represented by a single BD. Large banks are represented by up to 64 consecutive BDs and a very large bank by up to 4096 BDs. Large and very large banks need not use all 64 or 4096 consecutive BDs. They only use as many as needed to provide the virtual address space required. The entry also contains upper and lower limits of allowable offsets within the bank. Virtual addresses that are outside the limits generate a fault interrupt. This allows small banks, for example containing a message, to have only the virtual space reserved for it that it actually needs and provides a debugging check against bad pointers and indices. The BD also contains a key value and access control fields. The fields indicate whether read, write, or execute permission is granted to the instruction processor (3 bits). The Special Access Permissions (SAP) applies only to activities executing within the owning subsystem (really only those with a matching key value). The General Access Permissions (GAP) applies to everyone else and is usually zero (no access). The Exec sets a key value in the state of each activity which may be changed by gate and interrupt transitions. Protection Mechanisms The 2200 Series protection architecture uses three pieces of activity state that are reflected in the hardware state. They are Processor Privilege (PP), Ring, and Domain. Processor Privilege controls the ability to execute privileged instructions and access protected registers and other state. PP=0 is used by the Exec and gives full access to all instructions and privileged state. Exec activities and user activities that have used a gate to access an Exec API run at PP=0. PP=1 restricts most privileged instructions but does allow reading of the day clocks and reading the contents of some of the privileged registers. None of the privileged registers contain any truly sensitive information, but allowing general read access could easily lead to undetected errors in user programs. Basically at PP=1, instructions that can change the addressing environment, change the clocks, change instrumentation state, or perform I/O are all restricted. PP=1 is rarely used. PP=2 is the normal user mode and is state in which all other code executes. It is a further restriction of PP=1. There is also a PP=3 which further restricts the instructions a user program can execute, but it is not currently in use as too many existing programs were using some of those instructions. The intent was to restrict access to instructions that may be system model dependent. The Domain mechanism is the heart of the protection mechanism. Each BD (bank descriptor) has a lock field consisting of a ring number and domain number. There is also a key field in the state of each activity. If the key matches the lock or the ring in the key is less than the ring in the lock, the activity has Special Access Permission. Otherwise, the activity has General Access Permission. Ring allows overriding the Domain protection mechanism. User applications run at Ring=3. Protected subsystems run at Ring=2. This gives them access to their own data while still allowing them to access parameters and data in the calling user’s space. Note that it is still not possible for a thread to cause the protected subsystem to access some other user’s space as only this thread’s Bank Descriptor Tables are in use. Ring=0 is used by the OS and allows it to access its own data while still being able to access parameters passed from either user programs or protected subsystems. Gates are another part of the protection mechanism. A gate is a data structure that controls transitions between domains. A gate lives in a gate bank and the hardware enforces that all references to gates must be to addresses at a proper offset (multiple of a gate size) within a gate bank. A gate contains the target address, new values for PP, Ring, and Domain, and may contain a hidden parameter to be passed to the target. Protected subsystems are not directly accessible to other subsystems. Instead a subsystem must request that a gate be built in its gate bank for access to that subsystem. This permits the operating system to perform any access control checks. The linking system will then find the gate address associated with an entry point. In fact, the whole mechanism is usually transparently handled within the linking system. The hidden parameter permits, for example, a file I/O gate to contain the address or handle of the file control block. Since this is guaranteed to be correct as it was created by the OS when the user opened the file, many error checks can be eliminated from the path length to do I/O. Instruction Processors OS 2200 is designed to handle up to 32 instruction processors (or CPUs). A great deal of design has been done over the years optimize for this environment. For example, OS 2200 makes almost no use of critical sections in its design. There’s too high a probability of multiple processors executing the same code. Instead it uses data locking on the finest granularity data possible. Generally locks deal with a single instance of a data object (e.g., activity control structure or file control block) and are contained within the data structure of the object. This minimizes the likelihood of conflicts. When more global locks have to be set as when updating a list of objects, the lock is set only as long as it takes to update the links in the list. Even dispatching is done with separate locks for different priority levels. A check can be made for an empty priority level without setting a lock. The lock need only be set when adding or removing an item from the queue. The register set is in the visible address space. Registers appear to exist in the first 128 words (2008) of the current instruction bank (B0) when referenced as a data item. This does impose a restriction on compilers to not place any data constants in the first 128 words of a code bank. The result of this is an expansion of the instruction set without requiring additional operation codes. Register-to-register operations are accomplished with the register-storage operation codes. Typical instructions contain a function code, the target (or source) register, an index register, a base register and a displacement field. When the function code with its qualifier indicates immediate data, the displacement, base, i, and h fields combine to form a single 18-bit immediate value. This allows loading, adding, multiplying, etc. by small constants to eliminate a memory reference and the associated storage. Processor state as captured on a stack at an interrupt contains the information needed to both return control to the interrupted activity and to determine the type of the interrupt. Interrupts may occur in the middle of long instructions and the state deals with that possibility. Basic mode is another whole form of instruction formats and addressing. Basic mode provides compatibility with previous systems back to the 1108. For all practical purposes, the hardware architecture defines the rules by which addresses and instructions are converted to the above forms. The most obvious difference in basic mode is the lack of explicit B registers in instructions. Instead there are four implicitly used B registers (B12-B15). There is a complex algorithm using the limits of the banks represented by those B registers, the operand address and the B register within which the current instruction is found. The most interesting instructions in the 2200 repertoire are the locking and synchronization instructions. Conditional replace is familiar and quite similar to Compare and Swap in the Intel architecture. These instructions always gain exclusive use of the memory/cache-line holding the referenced word. TS and TSS check a bit in the referenced word. If the bit is clear, they set it and continue (TS) or skip (TSS). If the bit is set, they either interrupt (TS) or fall through to the next instruction(TSS). On a TS interrupt the OS takes one of several actions depending on the instruction sequence and activity priority. Real time and Exec activities simply get control back to allow retry unless there is an even higher-priority activity waiting. The presumption is that the lock is set on another processor and will soon be cleared. If it is a user activity not running at real time priority, it may have its priority temporarily reduced and be placed back in the dispatching queues. Alternatively, the code sequence may indicate that Test & Set Queuing is being used. In this case, the OS places the activity in a wait state and chains it to the end of the list of activities waiting for that particular lock. Activities clearing such a lock check to see if any are waiting and if so notify the OS to allow one of more to try again. Test & Set Queuing is typically used for synchronization within subsystems such as the database manager where activities from many programs may be executing. The result of these mechanisms is very efficient, low overhead, synchronization among activities. The queuing architecture is another interesting special case. It was specifically designed to allow very efficient handling of messaging where the number of messages waiting for processing could be almost unlimited. It is also aimed at reducing one of the primary costs of messaging, namely having to constantly move messages around in memory. Even moving them from the communication manager to the message queue subsystem to the processing program is eliminated. Instead each message is placed in a small bank of its own. Instructions allow placing the bank descriptors of these banks in a queue and removing them from a queue. When a message is placed in a queue, the sending program or subsystem no longer has any access to it. That bank is removed from its address space. When a message is retrieved from a queue, the bank becomes part of the receiver's address space. The queuing instructions also provide activity synchronization functions (e.g., wait for a message). Only "pointers" are moved and they are moved in a way that ensures security and integrity. Once moved, the data in the message is only visible to the recipient. I/O Processors All I/O on 2200 Series systems is handled by I/O processors. These processors offload large portions of the I/O path length and recovery, and by fully isolating the main system from I/O faults, interrupts, bus errors, etc. greatly improve reliability and availability. The I/O processors come in three different types (Storage, Communications, Clustering) but the only real difference is the firmware load. All I/O processors are controlled by the operating system. OS 2200 does provide a raw mode for I/O called "arbitrary device I/O," but even there the OS validates that the program is accessing an allowed device and handles all interrupts and faults before passing appropriate status on to the program. Programs must be granted privileges by the security officer to access devices in arbitrary mode and that may be limited by both the security officer and the system operator to specific devices. Arbitrary I/O is not allowed to a device that is also in use by any other program or the system. The device must be exclusively allocated to the program. The OS takes very general calls from programs and generates command packets with real memory and device addresses which are then passed to the I/O processor. Firmware in the I/O processor actually creates the device specific (e.g., SCSI) packets, sets up the DMA, issues the I/O, and services the interrupts. References Instruction set architectures

Operating System (OS)

Multi-booting Multi-booting is the act of installing multiple operating systems on a single computer, and being able to choose which one to boot. The term dual-booting refers to the common configuration of specifically two operating systems. Multi-booting may require a custom boot loader. Usage Multi-booting allows more than one operating system to reside on one computer; for example, if you have a primary operating system and an alternate system that you use less frequently. Another reason for multi-booting can be to investigate or test a new operating system without switching completely. Multi-booting allows a new operating system to configure all applications needed and migrate data before removing the old operating system, if desired. A possible alternative to multi-booting is virtualization, where a hypervisor is used to host one or more virtual machines running guest operating systems. Multi-booting is also useful in situations where different software require different operating systems. A multi-boot configuration allows a user to use all of this software on one computer. This is often accomplished by using a boot loader such as NTLDR, LILO, or GRUB which can boot more than one operating system. Multi-booting is also used by software developers when multiple operating systems are required for development or testing purposes. Having these systems on one machine is a way to reduce hardware costs. Technical issues Number of operating systems per volume (logical drive) In an OS/2 dual boot configuration, the C drive can contain both DOS and OS/2. The user issues the BOOT command from the DOS or OS/2 command line to do the necessary copy, move and rename operations and then reboot to the specified system on C:. Other systems provide similar mechanisms for alternate systems on the same logical drive. Number of operating systems per storage device In a multi-boot computer each of the multiple operating systems can reside on its own storage device, or some storage devices might contain more than one operating system in different partitions. The boot loader in or loaded by the MBR displays a menu of logical drives and loads the selected boot loader from the PBR of that drive. An example of a computer with one operating system per storage device is a dual-booting computer that stores Windows on one disk drive and Linux on another disk drive. In this case a multi-booting boot loader is not strictly necessary because the user can choose to enter BIOS configuration immediately after power-up and make the desired drive first in the boot-order list. However, it is more convenient to have a multi-booting boot loader on one of the drives, set BIOS once to always start booting from (i.e. load the boot loader from) that drive, and then allow the user to choose an operating system from that boot loader's menu. No special disk partitioning is necessary when each operating system has its own dedicated disk drive. An example of a computer with multiple operating systems per storage device is a dual-booting computer that stores both Windows and Linux on the same disk drive but where the bios in the system does not let the user boot individual drives and partitions. In this case a multi-booting boot loader is necessary. Also, the disk must be partitioned to give each operating system its own partition on the disk drive. This is necessary because each system has its own set of files and operating instructions. Also, when a completely separate operating system is used partitions may need to be formatted to a different format. For example, if you intend to install Windows and Linux, the Windows partition will be most likely formatted in the NTFS format and Linux Partition will most likely be formatted in the ext4 file format as Windows can't run off of ext4 and Linux can't run on NTFS. However, for example if a user intends to dual boot two versions of Windows (i.e. Windows 7 and Windows Vista) or two versions of Linux (i.e. Linux Mint and Ubuntu Linux), the same file system (e.g. NTFS or ext4) can be used across both drives and partitions. Partitioning The basic concept involves partitioning a disk to accommodate each planned installation, usually including separate partitions for boot, root, data storage and backups. Windows XP and 2000 Windows Vista's partitioners may not be compatible with XP and 2000 (see Logical disk manager#Compatibility problems). If you use Windows 2000 and XP, probably the safest approach (for disks under 2 TiB) is to use a CHS partition table alignment that is chosen by Windows XP/2000 (not Vista or Windows 7). If starting with a disk with nothing important on it, delete all partitions, unplug the disk or reboot, create at least one partition with Windows XP/2000 Disk Management or the XP/2000 installer, and format all FAT partitions. The alignment can be checked with Ranish Partition Manager: All partitions (including Extended Boot Record [EBR] extended partitions—type 05) should start at the beginning of a head, and end at the end of a cylinder. If nothing is shown in red (with error messages when you highlight them) you probably have a disk with a standard CHS partition table alignment. If you wish to edit the partition table with Linux, first run sfdisk with "--show-geometry" and "--show-pt-geometry". If these return the same geometry, it should be safe to use GParted, so long as it is set to round to cylinders, and you only add partitions to the end of the partition table. If you add a partition to the middle of the extended partition table, GParted will not put them in the order they are on the disk (so that hda7 will follow hda9 instead of hda6). The order can be fixed with a Linux fdisk advanced function. Most Linux partitioners that don't use parted, may not end EBR extended partitions (type 05) on the same sector as their logical drives. When GParted or parted edit these "nonstandard" partition tables, they will "fix" all these EBRs, so that the extended partitions end on the same sector as their logical drives. The partitioner then may show these partitions as having no "errors". This can also be checked using (for example) sfdisk -l -x -us /dev/hda. MBR loader An MBR loader, such as Air-Boot, replaces the standard boot code in track 0 with code that displays a selection menu and loads the selected system. Some, e.g., Air-Boot, can be configured either automatically or by the user at boot time, rather than requiring an external configuration menu. Linux boot loaders Linux loaders such as GRUB and LILO, can reside in the MBR or in a PBR. They use configuration files in /boot to control their selection menus, OS/2 Boot Manager The OS/2 Boot Manager must be installed in a primary partition. Tho OS/2 partitioning utilities can configure up to four systems in the menu, each of which can be either in a primary partition or in a logical volume within the extended logical partition. Newer loaders such as Air-Boot, GRUB and LILO offer more flexibility. Windows and Linux One popular multi-boot configuration is to dual-boot Linux and Windows operating systems, each contained within its own partition. Windows does not facilitate or support multi-boot systems, other than allowing for partition-specific installations, and no choice of boot loader is offered. However, most current Linux installers accommodate dual-booting (although some knowledge of partitions is desirable). Commonly installations proceed without incident but upon restart, the boot loader will recognize only one of the two operating systems. There are some advantages to installing a Linux boot manager/loader (usually GRUB) as the primary bootloader pointed to by the master boot record. Windows operating systems will be found by properly installed Linux bootloaders, but Windows boot managers do not recognize Linux installations (nor does Windows deal natively with Linux file systems). The MBR boot code can be backed up and restored with dd, available on System Rescue CD. It is often recommended that Windows be installed to the first primary partition. The boot loaders of both Windows and Linux identify partitions with a number derived by counting the partitions. (Note, both Windows and Linux count the partitions according to the ordering of the partitions in the partition table, which may be different from the order of the partitions on the disk.) Adding or deleting a partition at the end of a hard drive will have no effect on any partitions prior to it. However, if a partition is added or deleted at the beginning or middle of a hard drive, the numbering of subsequent partitions may change. If the number of the system partition changes, it requires boot loader reconfiguration in order for an operating system to boot and function properly. Windows must be installed into a primary partition (and in older systems this must be the first partition). Linux can be installed into a partition in any position on the hard drive and can also be installed into logical partitions (within the extended partition). If Linux is installed into a logical partition within the extended partition, it is unaffected by changes in the primary partitions. Neutral MBR An alternative to storing GRUB in the MBR is keeping Windows' or other generic PC boot code in the MBR, and installing GRUB or another bootloader into a primary partition other than that of Windows, thus keeping the MBR neutral. Operating system selection at boot time consequently depends on the bootloader configured within the primary partition that has the boot or "active" flag set on its partition table entry, which could be a bootloader of DOS, OS/2, eComStation, ArcaOS or BSD, in addition to Linux or Windows. With the boot flag set on the Windows primary, the Windows Boot Manager can be used to chainload another installed bootloader by employing usage of a program like EasyBCD. This means the active partition's boot manager will first prompt the user for selection what OS to boot, then load another if necessary, such as GRUB, even a bootloader installed to a logical partition, and then GRUB will load the Linux kernel as it normally would were GRUB installed to the MBR. The active partition could also be one that exists for no purpose other than choosing an operating system to boot, such as the Boot Manager that shipped with IBM's OS/2 Warp and its derivatives. Apple Boot Camp Boot Camp allows owners of Intel-based Apple Macintosh computers to install Windows XP, Vista, 7, 8, and 10 on their Macs. The software comes bundled with Mac OS X since version 10.5 (Leopard). Previously the application was available in beta version as a download from Apple's website. Boot Camp allows non-destructive disk partitioning and resizing of HFS+ filesystems, boot menu options, and an option to burn a CD with necessary device drivers. Since Windows XP is incompatible with Extensible Firmware Interface (the successor to legacy BIOS), the firmware on early Intel Macs needs to be updated to support BIOS emulation first. BIOS emulation is achieved with a compatibility support module (CSM). Apple does not support non-Windows partition formats or drivers so therefore configuring other operating systems is not directly possible through Boot Camp itself. However, any operating system which can utilize the BIOS emulation of Intel Macintosh can be made to work, including non-XP versions of Windows. The Ubuntu Linux distribution is particularly popular for this purpose because they provide an option to use proprietary device drivers along with open source drivers. See also Booting Comparison of boot loaders GNU GRUB Ext2Fsd support for ext2/3/4 under Microsoft Windows Multiboot Specification Windows To Go NeoSmart Technologies' EasyBCD, a free program to configure Multi-booting on Windows XOSL, a free, graphical, open source boot loader Virtualization References External links Multiboot Specification Dual, Triple, Quad Boot a Macbook with Mac OS X, Ubuntu Linux, Windows XP, and Windows Vista Installing Windows XP:Dual-Booting Versus Single Booting Booting Disk partitions

Operating System (OS)

Lightweight Kernel Operating System A lightweight kernel (LWK) operating system is one used in a large computer with many processor cores, termed a parallel computer. A massively parallel high-performance computing (HPC) system is particularly sensitive to operating system overhead. Traditional multi-purpose operating systems are designed to support a wide range of usage models and requirements. To support the range of needs, a large number of system processes are provided and are often inter-dependent on each other. The computing overhead of these processes leads to an unpredictable amount of processor time available to a parallel application. A very common parallel programming model is referred to as the bulk synchronous parallel model which often employs Message Passing Interface (MPI) for communication. The synchronization events are made at specific points in the application code. If one processor takes longer to reach that point than all the other processors, everyone must wait. The overall finish time is increased. Unpredictable operating system overhead is one significant reason a processor might take longer to reach the synchronization point than the others. Examples Custom lightweight kernel operating systems, used on some of the fastest computers in the world, help alleviate this problem. The IBM Blue Gene line of supercomputers runs various versions of CNK operating system. The Cray XT4 and Cray XT5 supercomputers run Compute Node Linux while the earlier XT3 ran the lightweight kernel Catamount which was based on SUNMOS. Sandia National Laboratories has an almost two-decade commitment to lightweight kernels on its high-end HPC systems. Sandia and University of New Mexico researchers began work on SUNMOS for the Intel Paragon in the early 1990s. This operating system evolved into the Puma, Cougar - which achieved the first teraflop on ASCI Red - and Catamount on Red Storm. Sandia continues its work in LWKs with a new R&D effort, called kitten. Characteristics Although it is surprisingly difficult to exactly define what a lightweight kernel is, there are some common design goals: Targeted at massively parallel environments composed of thousands of processors with distributed memory and a tightly coupled network. Provide necessary support for scalable, performance-oriented scientific applications. Offer a suitable development environment for parallel applications and libraries. Emphasize efficiency over functionality. Maximize the amount of resources (e.g., CPU, memory, and network bandwidth) allocated to the application. Seek to minimize time to completion for the application. Implementation LWK implementations vary, but all strive to provide applications with predictable and maximum access to the central processing unit (CPU) and other system resources. To achieve this, simplified algorithms for scheduling and memory management are usually included. System services (e.g., daemons), are limited to the absolute minimum. Available services, such as job launch are constructed in a hierarchical fashion to ensure scalability to thousands of nodes. Networking protocols for communication between nodes in the system are also carefully selected and implemented to ensure scalability. One such example is the Portals network programming application programming interface (API). Lightweight kernel operating systems assume access to a small set of nodes that are running full-service operating systems to offload some of the necessary services: login access, compiling environments, batch job submission, and file I/O. By restricting services to only those that are absolutely necessary and by streamlining those that are provided, the overhead (sometimes called noise) of the lightweight operating system is minimized. This allows a significant and predictable amount of the processor cycles to be given to the parallel application. Since the application can make consistent progress on each processor, they will reach their synchronization points faster, ideally at the same time. Lost wait time is reduced. Future The last supercomputers running lightweight kernels are the remaining IBM Bluegene systems running CNK. A new direction for lightweight kernels is to combine them with a full-featured OS, such as Linux, on a many-core node. These multikernel operating systems run a lightweight kernel on some of the CPU cores of a node, while other cores provide services that are omitted in lightweight kernels. By combining the two, users get the Linux features they need but also the deterministic behavior and scalability of lightweight kernels. References Supercomputer operating systems Massively parallel computers

Operating System (OS)

MK-DOS MK-DOS was one of the most widespread operating systems for Elektronika BK personal computers, developed by Mikhail Korolev and Dmitriy Butyrskiy from 1993. Like ANDOS, the system provided full compatibility for all models, emulating the BK-0010 environments on the more modern BK-0011 and BK-0011M machines. All program requests to a magnetic tape (if they were made through proper ROM functions) were redirected to the disk. The system supported up to 4 physical disk drives (the actual number was limited by the disk ROM installed) and as many hard disk partitions as the number of letters in the Latin alphabet, which could be used as separate logical drives, each with a volume of up to 32 MB (See also: drive letter assignment). Starting from version 3.0 the system also supported mounting disk images as logical drives. When booted on a BK-0011 or BK-0011M the system automatically created a RAM disk in the computer's memory. The most widespread file system along MK-DOS users was MicroDOS. It did not support file fragmentation (like the file system used with RT-11) and required frequent spatial reallocation to maintain optimum contiguous free space (RT-11 users would use the 'SQUEEZE' command, which worked the same way as the *COMPACT command on Acorn's DFS for the BBC Micro). Although MK-DOS was incompatible with the RT-11's file system, both shared many principles. MicroDOS' file system had read-only support in ANDOS. The filename length was limited by 14 symbols (the filename extension was not recognized separately and was considered as part of the filename). A minimal installation of the system took as little as 8 KB of the computer's memory. It had a functional Norton Commander-like file manager called MCommander. It also shipped with a number of utilities including drivers for the RT-11, FAT12 and CSI-DOS file systems as add-ons for the file manager. External links Disk image of MK-DOS 2.10 Disk image of MK-DOS 3.15 Disk image of MK-DOS 3.17 Disk image of MK-DOS 3.18 Mikhail Korolev homepage (Original documentation for MK-DOS 3.15) V.P.Yurov. BK-0010(.01) with disk drive (Comparison of operating systems for BK-0010). Magazine "Personal computer BK-0010 - BK-0011M", 1993 V.P.Yurov. Disk operating systems for BK-0011(M). Magazine "Personal computer BK-0010 - BK-0011M", 1994 (djvu) Elektronika BK operating systems

Operating System (OS)

AMSDOS AMSDOS is a disk operating system for the 8-bit Amstrad CPC Computer (and various clones). The name is a contraction of Amstrad Disk Operating System. AMSDOS first appeared in 1984 on the CPC 464, with added 3 inch disk drive, and then on the CPC 664 and CPC 6128. Relatively fast and efficient for its time, AMSDOS was quicker and more effective than most of its contemporaries. AMSDOS was provided built into ROM (either supplied with the external disk drive or in the machine ROM, depending on model) and was accessible through the built-in Locomotive BASIC as well as through firmware routines. Its main function was to map the cassette access routines (which were built into every CPC model) through to a disk drive. This enabled the majority of cassette-based programs to work with a disk drive with no modification. AMSDOS was able to support up to two connected disk drives. Commands AMDOS extends the AMSTRAD BASIC by the addition of a number of external commands which are identified by a preceding ¦ (bar) symbol. The following is a list of external commands supported by AMSDOS. ¦A ¦B ¦CPM ¦DIR ¦DISC ¦DISC.IN ¦DISC.OUT ¦DRIVE ¦ERA ¦REN ¦TAPE ¦TAPE.IN ¦TAPE.OUT ¦USER Alternatives Other disk operating systems for the Amstrad range included CP/M (which was also bundled with an external disk drive, or built-in on ROM depending on model), RAMDOS, which allowed the full (800K) capacity of single-density 3 ½" disks to be used providing a suitable drive was connected and SymbOS. References Amstrad CPC Disk operating systems 1984 software

Operating System (OS)

SymbOS SYmbiosis Multitasking Based Operating System (SymbOS) is a multitasking operating system for Zilog Z80-based 8-bit computer systems. Contrary to early 8-bit operating systems it is based on a microkernel, which provides preemptive and priority-oriented multitasking and manages random-access memory (RAM) with a size of up to 1024 KB. SymbOS contains a Microsoft Windows like graphical user interface (GUI), supports hard disks with a capacity of up to 128 GB and can already be booted on an unexpanded Amstrad CPC-6128, a 128K-MSX2 and an Amstrad PCW. As of August 30th 2017 it is available for the Amstrad CPC series of computers, all MSX models starting from the MSX2 standard, MSX with V9990 graphics chip, all Amstrad PCW models, CPC-TREX, C-ONE and the Enterprise 64/128 computers. Motivation and rationale SymbOS was originally started as an experiment to find out to what extent it is possible to implement a multitasking operating system with a windowed GUI on an 8-bit computer from 1985. GEOS contributed to the motivation, but the structure and features of SymbOS aren't similar to that system. The release in 2006 proved that such a "mini windows" system is possible on a then 20-year-old home computer with only quantitative limitations. SymbOS is one of the largest retro computing software projects of recent years. One of the goals of the project is to allow these old machines to be used like a modern PC, using hardware extensions. Although only an 8-bit CPU, the Z80 can run a preemptive multitasking operating system. Features such as memory protection, which the Z80 lacks, are not essential in such an OS. For example, AmigaOS also lacks memory protection. The MP/M OS proved that multitasking on the Z80 CPU was possible. Yet, it was generally unavailable for home computers. While the MOS Technology 6502 cannot move the stack pointer, the Z80 can freely relocate it to any position in memory, which makes it easier to implement preemptive multitasking. The existence of an alternative register set accelerates context switching between tasks dramatically. The restriction of Z80 system to a 64 KB address space can be solved with bank switching. In this way, computers like the Amstrad CPC and PCW, MSX, Enterprise or SAM Coupé can access hundreds or thousands of kilobytes of memory. Design SymbOS includes a microkernel, which can perform task management, memory management and inter-process communication. Task management For task management, a combination of preemptive and cooperative multitasking was chosen, which makes different task priorities possible. Preemptive means that tasks are interrupted after a certain amount of time by the operating system, in order to share the CPU time with other tasks. Cooperatively means that a task stops using CPU time by itself. It does that, if it's finished with its current job or waiting for a certain event. Because of this combination it is possible to assign priorities. Tasks with low priority get CPU time only if all tasks with higher priorities are not then working. Memory and banking management Memory management divides the entire RAM into small 256 byte blocks, which can be assigned dynamically. Applications are always running in a secondary 64 KB RAM bank, where no memory space is occupied by the operating system or the video memory. That makes it possible to reserve up to 63 KB in one piece. Banking management ensures that the system can administer memory with a size of up to one megabyte, even though the Z80 CPU has only a 16-bit address bus. It makes transparent access to memory and functions placed in other 64 KB banks possible. Interprocess communication Communication between different tasks and the operating system usually does not take place via calls, but is done via messages. This is necessary inside a multitasking environment to avoid organization problems with the stack, global variables and shared system resources. The SymbOS kernel supports synchronous and asynchronous IPC. File system management SymbOS supports the file systems CP/M, AMSDOS, and File Allocation Table (FAT) 12-16-32, on all platforms. With the last one, SymbOS can address mass storage devices with a capacity of up to 128 GB. Also, the ability to administer files with a size of up to 2 GB is uncommon for an 8-bit system. Because of the FAT support data exchange with other computers is quite easy, as most 32 and 64 bit operating systems do support the three FAT file systems. Interface The graphical user interface (GUI) of SymbOS works in a fully object-oriented manner. The look and feel mimics that of Microsoft Windows. It contains the well-known task bar with the clock and the "start" menu and can open up to 32 windows that can be moved, resized and scrolled. The whole system is written in optimized assembly language, meaning that the GUI runs as fast as the host machine supports. Content of a window is defined with "controls" that are primitive GUI elements such as sliders, check boxes, text lines, buttons or graphics. The background or invisible areas of a window don't need to be saved in a separate bitmap buffer. If an area needs to be restored on the display, its contents will be redrawn instead. This makes SymbOS GUI much more memory-friendly compared to most other 8-bit GUIs. Applications There are several standard applications available for SymbOS, which are designed to resemble similar software available on other operating systems. Examples include Notepad, SymCommander (similar to Norton Commander), SymShell (cmd.exe), SymZilla (Mozilla Firefox), SymPlay (QuickTime), SymAmp (Winamp) and Minesweeper. Commands The following list of commands is supported by SymShell. ATTRIB CD CLS COLOR COPY DATE DEL DIR ECHO EXIT FULL HELP MD MOVE PAUSE RD REM REN SIZE TIME TYPE VER Development and release SymbOS was originally developed for the Amstrad CPC. Its modular structure, with strict separation of general and hardware components, makes porting to other Z80-based systems comparatively easy. The MSX computers starting with the MSX2 standard have been supported since summer 2006. The Amstrad PCW port has been available since August 2007. Versions for the Enterprise 128, the SAM Coupé and such clones of ZXSpectrum as ATM-turbo 2+ and ZX-Evolution/BaseConf are possible, too, as they fulfill the requirements for SymbOS. By keeping a basic condition for an operating system, the strict separation of hardware and application software by an intermediate layer, SymbOS applications run platform-independently on each computer and doesn't need to be adapted for different systems, with the obvious exception of applications that directly access particular hardware. See also Contiki MSX-DOS OS-9 References External links SymbOS installation help file SymbOS mailing list Page at the CPCWiki SymbOS demo video running on a real MSX turboR GT with MP3MSX cartridge Amstrad CPC MSX Hobbyist operating systems

Operating System (OS)

Unix architecture A Unix architecture is a computer operating system system architecture that embodies the Unix philosophy. It may adhere to standards such as the Single UNIX Specification (SUS) or similar POSIX IEEE standard. No single published standard describes all Unix architecture computer operating systems - this is in part a legacy of the Unix wars. Description There are many systems which are Unix-like in their architecture. Notable among these are the Linux distributions. The distinctions between Unix and Unix-like systems have been the subject of heated legal battles, and the holders of the UNIX brand, The Open Group, object to "Unix-like" and similar terms. For distinctions between SUS branded UNIX architectures and other similar architectures, see Unix-like. Kernel A Unix kernel — the core or key components of the operating system — consists of many kernel subsystems like process management, scheduling, file management, device management, network management, memory management, and dealing with interrupts from hardware devices. Each of the subsystems has some features: Concurrency: As Unix is a multiprocessing OS, many processes run concurrently to improve the performance of the system. Virtual memory (VM): Memory management subsystem implements the virtual memory concept and users need not worry about the executable program size and the RAM size. Paging: It is a technique to minimize the internal as well as the external fragmentation in the physical memory. Virtual file system (VFS): A VFS is a file system used to help the user to hide the different file systems complexities. A user can use the same standard file system related calls to access different file systems. The kernel provides these and other basic services: interrupt and trap handling, separation between user and system space, system calls, scheduling, timer and clock handling, file descriptor management. Features Some key features of the Unix architecture concept are: Unix systems use a centralized operating system kernel which manages system and process activities. All non-kernel software is organized into separate, kernel-managed processes. Unix systems are preemptively multitasking: multiple processes can run at the same time, or within small time slices and nearly at the same time, and any process can be interrupted and moved out of execution by the kernel. This is known as thread management. Files are stored on disk in a hierarchical file system, with a single top location throughout the system (root, or "/"), with both files and directories, subdirectories, sub-subdirectories, and so on below it. With few exceptions, devices and some types of communications between processes are managed and visible as files or pseudo-files within the file system hierarchy. This is known as everything is a file. However, Linus Torvalds states that this is inaccurate and may be better rephrased as "everything is a stream of bytes". The UNIX operating system supports the following features and capabilities: Multitasking and multiuser Programming interface Use of files as abstractions of devices and other objects Built-in networking (TCP/IP is standard) Persistent system service processes called "daemons" and managed by init or inet Criticism The Unix-Haters Handbook covers some of these design features as failures from the user point of view. However, although some information is quite dated and cannot be applied to modern Unixes or Unix-like operating systems such as Linux, Eric S. Raymond discovered that several issues are still prevailing, while others were resolved. Raymond concludes that not all concepts behind Unix can be deemed as non-functional even though the book's intention may have been to portray Unix as inferior without encouraging discussions with developers to actually fix the issues. See also Architecture of Windows NT References Operating systems by architecture Unix Computer architecture

Operating System (OS)

Single UNIX Specification The Single UNIX Specification (SUS) is the collective name of a family of standards for computer operating systems, compliance with which is required to qualify for using the "UNIX" trademark. The core specifications of the SUS are developed and maintained by the Austin Group, which is a joint working group of IEEE, ISO JTC 1 SC22 and The Open Group. If an operating system is submitted to The Open Group for certification, and passes conformance tests, then it is deemed to be compliant with a UNIX standard such as UNIX 98 or UNIX 03. Very few BSD and Linux-based operating systems are submitted for compliance with the Single UNIX Specification, although system developers generally aim for compliance with POSIX standards, which form the core of the Single UNIX Specification. History 1980s: Motivation The SUS emerged from a mid-1980s project to standardize operating system interfaces for software designed for variants of the Unix operating system. The need for standardization arose because enterprises using computers wanted to be able to develop programs that could be used on the computer systems of different manufacturers without reimplementing the programs. Unix was selected as the basis for a standard system interface partly because it was manufacturer-neutral. 1988: POSIX In 1988, these standards became IEEE 1003 (also registered as ISO/IEC 9945), or POSIX, which loosely stands for Portable Operating System Interface. 1990s: Spec 1170 In the early 1990s, a separate effort known as the Common API Specification or Spec 1170 was initiated by several major vendors, who formed the COSE alliance in the wake of the Unix wars. This specification became more popular because it was available at no cost, whereas the IEEE charged a substantial fee for access to the POSIX specification. Management over these specifications was assigned to X/Open who also received the Unix trademark from Novell in 1993. Unix International (UI) merged into Open Software Foundation (OSF) in 1994 only to merge with X/Open to form The Open Group in 1996. 1994: Single UNIX Specification This was a repackaging of the X/Open Portability Guide (XPG), Issue 4, Version 2. 1995 Edition In 1995, the Open Group released the Single UNIX Specification Version 1, 1995 Edition. This specification consisted of: System Interface Definitions, Issue 4, Version 2, System Interfaces and Headers, Issue 4, Version 2, Commands and Utilities, Issue 4, Version 2, X/Open Curses, Issue 4 Version 2, Networking Services, Issue 4, and was at the core of the UNIX 95 brand. 1997: Single UNIX Specification version 2 In 1997, the Open Group released the Single UNIX Specification Version 2. This specification consisted of: the Base Definitions, Issue 5, the System Interfaces and Headers, Issue 5, the Commands and Utilities, Issue 5, the Networking Services, Issue 5, the X/Open Curses, Issue 4, Version 2, and was at the core of the UNIX 98 brand. 2001: Single UNIX Specification version 3, POSIX:2001 Beginning in 1998, a joint working group known as the Austin Group began to develop the combined standard that would be known as the Single UNIX Specification Version 3 and as POSIX:2001 (formally: IEEE Std 1003.1-2001). It was released on January 30, 2002. This standard consisted of: the Base Definitions, Issue 6, the System Interfaces and Headers, Issue 6, the Commands and Utilities, Issue 6, and is at the core of the UNIX 03 brand. 2004: POSIX:2004 In 2004, a new edition of the POSIX:2001 standard was released, incorporating two technical corrigenda. It is called POSIX:2004 (formally: IEEE Std 1003.1-2004). 2008: Single UNIX Specification version 4, POSIX:2008 In December 2008, the Austin Group published a new major revision, known as POSIX:2008 (formally: IEEE Std 1003.1-2008). This is the core of the Single UNIX Specification, Version 4 (SUSv4). This standard consists of: the Base Definitions, Issue 7, the System Interfaces and Headers, Issue 7, the Commands and Utilities, Issue 7. 2013 Edition The Technical Corrigendum 1 is mostly targeting internationalization and it introduces a role-based access model. It was published in 2012 for the Unix Base specification and it is registered as the 2013 Edition of POSIX 2008. A trademark UNIX V7 (not to be confused with V7 UNIX, the version of Research Unix from 1979) has been created to mark compliance with SUS Version 4. 2016 Edition The Technical Corrigendum 2 has been published in September 2016, leading into IEEE Std 1003.1-2008, 2016 Edition and Single UNIX Specification, Version 4, 2016 Edition. 2018 Edition In January 2018 an "administrative rollup" edition, susv4-2018, was released. It incorporates Single UNIX Specification version 4 TC1 and TC2, and is technically identical to the 2016 edition. Specification SUSv3 totals some 3700 pages, which are divided into four main parts: Base Definitions (XBD) - a list of definitions and conventions used in the specifications and a list of C header files which must be provided by compliant systems. 84 header files in total are provided. Shell and Utilities (XCU) - a list of utilities and a description of the shell, sh. 160 utilities in total are specified. System Interfaces (XSH) - contains the specification of various functions which are implemented as system calls or library functions. 1123 system interfaces in total are specified. Rationale (XRAT) - the explanation behind the standard. The standard user command line and scripting interface is the POSIX shell, an extension of the Bourne Shell based on an early version of the Korn Shell. Other user-level programs, services and utilities include awk, echo, ed, vi, and hundreds of others. Required program-level services include basic I/O (file, terminal, and network) services. A test suite accompanies the standard. It is called PCTS or the POSIX Certification Test Suite. Additionally, SUS includes CURSES (XCURSES) specification, which specifies 372 functions and 3 header files. All in all, SUSv3 specifies 1742 interfaces. Note that a system need not include source code derived in any way from AT&T Unix to meet the specification. For instance, IBM OS/390, now z/OS, qualifies as a "Unix" despite having no code in common. Marks for compliant systems There are five official marks for conforming systems: UNIX 93 UNIX 95 - the mark for systems conforming to version 1 of the SUS UNIX 98 - the mark for systems conforming to version 2 of the SUS UNIX 03 - the mark for systems conforming to version 3 of the SUS UNIX V7 - the mark for systems conforming to version 4 of the SUS (including Corrigenda) Compliance Currently registered UNIX systems AIX AIX version 7, at either 7.1 TL5 (or later) or 7.2 TL2 (or later) are registered as UNIX 03 compliant. AIX version 7, at 7.2 TL5 (or later) are registered as UNIX V7 compliant. EulerOS EulerOS 2.0 for the x86-64 architecture is registered as UNIX 03 compliant. The UNIX 03 conformance statement shows that the standard C compiler is from the GNU Compiler Collection (), and that the system is a Linux distribution of the Red Hat family. HP-UX HP-UX 11i V3 Release B.11.31 is registered as UNIX 03 compliant. Previous releases were registered as UNIX 95. HP-UX 11i features also provide partial conformance to the UNIX 98 specification. macOS Apple macOS (formerly known as Mac OS X or OS X) is registered as UNIX 03 compliant. The first version registered was Mac OS X 10.5 Leopard, certified on October 26, 2007 (on x86 systems). All newer versions of macOS, up to macOS 12 Monterey, have been registered, with macOS 11 and 12 registered on both x86-64 and ARM64 systems. Xinuos UnixWare 7.1.3 and later is registered as UNIX 95 compliant. SCO OpenServer 5 and 6 are registered as UNIX 93 compliant. z/OS IBM z/OS 1.2 and higher is registered as UNIX 95 compliant. z/OS 1.9, released on September 28, 2007, and subsequent releases "better align" with UNIX 03. Previously registered UNIX systems FTX DNCP Series running FTX Release 3 was registered as UNIX 93 compliant. Solaris Solaris 11.4 was previously registered as UNIX v7 compliant in 2018. Solaris 11 and Solaris 10 was registered as UNIX 03 compliant on 32-bit and 64-bit x86 (X86-64) and SPARC systems. Solaris 8 and 9 was registered as UNIX 98 compliant on 32-bit x86 and SPARC systems; 64-bit x86 systems were not supported. Solaris 2.5.1 was also registered as UNIX 95 compliant on the PReP PowerPC platform in 1996, but the product was withdrawn before more than a few dozen copies had been sold. Reliant UNIX The last Reliant UNIX versions were registered as UNIX 95 compliant (XPG4 hard branding). Inspur K-UX Inspur K-UX 2.0 and 3.0 for the x86-64 architecture were certified as UNIX 03 compliant. The UNIX 03 conformance statement for Inspur K-UX 2.0 and 3.0 shows that the standard C compiler is from the GNU Compiler Collection (), and that the system is a Linux distribution of the Red Hat family. Tru64 UNIX Tru64 UNIX V5.1A and later were registered as UNIX 98 compliant. Other Other operating systems previously registered as UNIX 95 or UNIX 93 compliant: IBM OS/390 NCR UNIX SVR4 NEC UX/4800 SGI IRIX 6.5 Non-registered Unix-like systems Developers and vendors of Unix-like operating systems such as Linux, FreeBSD, and MINIX, typically do not certify their distributions and do not install full POSIX utilities by default. Sometimes, SUS compliance can be improved by installing additional packages, but very few Linux systems can be configured to be completely conformant. Darwin, the open source subset of macOS, has behavior that can be set to comply with UNIX 03. FreeBSD previously had a "C99 and POSIX Conformance Project" which aimed for compliance with a subset of the Single UNIX Specification, and documentation where there were differences. For Linux, the Linux Standard Base was formed in 2001 as an attempt to standardize the internal structures of Linux-based systems for increased compatibility. It is based on the POSIX specifications, the Single UNIX Specification, and other open standards, and also extends them in several areas; but there are some conflicts between the LSB and The POSIX standards. However, although these standards are commonly accepted, few Linux distributions actually go through certification as LSB compliant. See also List of Unix commands Unix wars Functional specification UNIX manual Open system (computing) Open standard POSIX References Sources External links The Single UNIX Specification IEEE standards Open Group standards POSIX Unix standards

Operating System (OS)

Computing platform A computing platform or digital platform is an environment in which a piece of software is executed. It may be the hardware or the operating system (OS), even a web browser and associated application programming interfaces, or other underlying software, as long as the program code is executed with it. Computing platforms have different abstraction levels, including a computer architecture, an OS, or runtime libraries. A computing platform is the stage on which computer programs can run. A platform can be seen both as a constraint on the software development process, in that different platforms provide different functionality and restrictions; and as an assistant to the development process, in that they provide low-level functionality ready-made. For example, an OS may be a platform that abstracts the underlying differences in hardware and provides a generic command for saving files or accessing the network. Components Platforms may also include: Hardware alone, in the case of small embedded systems. Embedded systems can access hardware directly, without an OS; this is referred to as running on "bare metal". A browser in the case of web-based software. The browser itself runs on a hardware+OS platform, but this is not relevant to software running within the browser. An application, such as a spreadsheet or word processor, which hosts software written in an application-specific scripting language, such as an Excel macro. This can be extended to writing fully-fledged applications with the Microsoft Office suite as a platform. Software frameworks that provide ready-made functionality. Cloud computing and Platform as a Service. Extending the idea of a software framework, these allow application developers to build software out of components that are hosted not by the developer, but by the provider, with internet communication linking them together. The social networking sites Twitter and Facebook are also considered development platforms. A virtual machine (VM) such as the Java virtual machine or .NET CLR. Applications are compiled into a format similar to machine code, known as bytecode, which is then executed by the VM. A virtualized version of a complete system, including virtualized hardware, OS, software, and storage. These allow, for instance, a typical Windows program to run on what is physically a Mac. Some architectures have multiple layers, with each layer acting as a platform to the one above it. In general, a component only has to be adapted to the layer immediately beneath it. For instance, a Java program has to be written to use the Java virtual machine (JVM) and associated libraries as a platform but does not have to be adapted to run for the Windows, Linux or Macintosh OS platforms. However, the JVM, the layer beneath the application, does have to be built separately for each OS. Operating system examples Desktop, laptop, server AmigaOS, AmigaOS 4 Chrome OS FreeBSD, NetBSD, OpenBSD IBM i Linux Microsoft Windows OpenVMS Classic Mac OS - discontinued in 2011 macOS OS/2 Solaris Tru64 UNIX VM QNX z/OS Mobile Android Bada - discontinued in 2013 BlackBerry OS - discontinued in 2013 Fire OS Firefox OS - discontinued in 2016 iOS iPadOS Embedded Linux Palm OS - discontinued in 2011 Symbian - discontinued in 2012 Tizen WebOS LuneOS Windows Mobile - discontinued in 2010 Windows Phone - discontinued in 2017 kaiOS Software examples Binary Runtime Environment for Wireless (BREW) Cocoa Cocoa Touch .NET Mono .NET Framework Silverlight Flash AIR GNU Java Java ME Java SE Java EE JavaFX JavaFX Mobile LiveCode Microsoft XNA Mozilla Prism, XUL and XULRunner Mozilla WebExtensions API is modeled after Google Chrome's API. Thus Firefox extensions are now largely compatible with their Chrome counterparts. Web platform Oracle Database Qt SAP NetWeaver Shockwave Smartface Universal Windows Platform Windows Runtime Hardware examples Ordered roughly, from more common types to less common types: Commodity computing platforms ARM architecture based devices Android smartphones iPhone smartphones and iPad tablet devices running iOS or iPadOS, from Apple Macintosh computers using Apple silicon. Raspberry Pi or Gumstix full function miniature computers with Linux ARM servers with Unix-like systems such as Linux or BSD variants Newton devices running the Newton OS, from Apple ChromeBooks from various manufacturers Wintel, that is, Intel x86 or compatible personal computer hardware with Windows operating system Macintosh, custom Apple Inc. hardware and Classic Mac OS and macOS operating systems, originally 68k-based, then PowerPC-based, then x86-based, now migrated to Apple silicon with ARM architecture CPUs x86 with Unix-like systems such as Linux or BSD variants CP/M computers based on the S-100 bus, maybe the earliest microcomputer platform Video game consoles, any variety (PlayStation, Xbox, Nintendo) 3DO Interactive Multiplayer, that was licensed to manufacturers Apple Pippin, a multimedia player platform for video game console development Non-commodity RISC or Itanium processor based machines Unix variants or Unix-like systems SPARC architecture computers running Solaris, illumos, or Linux operating systems POWER ISA, PowerPC, or Power ISA computers running IBM AIX or Linux operating systems Itanium computers running HP-UX DEC Alpha machines computers Tru64 UNIX PowerPC or Power ISA computers running IBM i DEC Alpha and Itanium computers running OpenVMS Midrange computers with their custom operating systems Mainframe computers with their custom operating systems, such as IBM z/OS Supercomputer architectures See also Cross-platform Platform virtualization Third platform Platform ecosystem References External links Ryan Sarver: What is a platform?

Operating System (OS)

Objective Systems Integrators Objective Systems Integrators (OSI) is a multinational computer technology corporation that develops, manufactures, licenses, and supports software products which automate the monitoring, control, delivery, and management of services for multinational corporation service providers including: Wireless service providers IPTV service providers Transmission service providers OSI was acquired by MYCOM and MYCOM OSI was formed in 2014. History Sobha Group ownership OSI, a wholly owned subsidiary of the Sobha Group, develops and markets an OSS suite targeted for Communications Service Providers. February 2008, Longview Software and OSI sign an Asset Purchase Agreement for OSI to acquire Longview intellectual property, products and technology. Longview software is a maker of off-the-shelf tools and custom applications that add value to many Operational Support System (OSS) and Business Support System (BSS) frameworks in the telecommunications industry. Agilent Technologies ownership Agilent acquired OSI in January 2001 for approximately $665 million. Agilent subsequently built an OSS business around this and other technology, but decided in 2007 to exit this market segment and focus on its test and measurement and life sciences businesses. 2001–2007, OSI is acquired by Agilent Technologies to help integrate Test and Measurement into the OSS market. NetExpert integrated Test & Measurement probe solutions to provide overarching Service Management integration. OSI was under Agilent's OSS Division (Assurance Services Division) as a NETeXPERT Business Unit. Pre-Agilent history During the period of 1995–2001, OSI was traded on NASDAQ as OSII. OSI introduces the MASTER series of products to the market aligned around key technology areas such as fixed line networks, SONET/SDH network, and wireless networks. In 1997 OSI reached its 100th worldwide communications service provider (CSP) customer base. 1998–2001, OSI’s NetExpert Virtual Service Management (VSM), and Virtual Process Management (VPM) frameworks leverage the UMA (Unified Management Architecture). OSI introduces several new applications in key Communications Service Provider functional areas namely Fault management, Performance Management, Configuration Management, and Accounting Management. Solutions are introduced to accelerate time to value for wireless, wireline, and the Internet Protocol Suite of services. Products OSI launches NetExpert Neon May 2009 for service assurance solutions focused on services and customers: Service Health - Service Quality and Impact management leveraging industry standard portal technology for a holistic view of critical customer services. Customer Health - Customer SLA, Experience Analysis, and Insight of corporations, groups within corporations, and individuals. See also Agilent Technologies Sobha Renaissance Information Technology Operations support systems Communications Service Provider Service management Expert system Reference Books Plunkett, J (1996). "Plunkett's Infotech Industry Almanac" - Page 75 Books Minoli, D, Golway, T, and Smith, N (1996) "Planning and Managing ATM Networks" - Google Books Prentice Hall PTR. Terplan, K (1998). "Telecom Operations Management Solutions with NetExpert" Amazon,Google Books CRC Press LLC Terplan, K (1999). "Web-Based Systems & Network Management" - Page 185 Google Books Terplan, K (1999). "Applications for Distributed Systems and Network Management" - Page 101 Google Books Van Nostrand Reinhold References External links Telecommunications companies of the United States Telephony software Software companies based in California Software companies of the United States

Operating System (OS)

IS-DOS iS-DOS is a disk operating system (DOS) for Russian ZX Spectrum clones. iS-DOS was developed in 1990 or 1991, by Iskra Soft, in Leningrad, Soviet Union, now Saint Petersburg, Russia. It handles floppy disks (double sided, double density), hard disk drivess, and CD-ROMs. Maximum iS-DOS partition size on a hard disk is 16 MiB. Unlike TR-DOS, iS-DOS is random-access memory (RAM) based. Such operating systems reduce the amount of memory available for user programs. Versions iS-DOS Chic is a version developed for Nemo KAY. It provides more memory for user programs. TASiS, based on iS-DOS Chic, is a modern version developed by NedoPC for ATM Turbo 2+ in 2006. It supports text mode and high memory of that machine. Distributors Slot Ltd. (Moscow) distributed iS-DOS in Moscow and regions in 1990s, and issued paper books. Nemo (Saint Petersburg) distributed iS-DOS in ex-USSR until 2004, and issued Open Letters electronic press. iS-DOS Support Team (Saratov Oblast) distributes iS-DOS in ex-USSR and issues iS-Files electronic press. NedoPC distributes TASiS as freeware. Books Картавцев И.Ю, Самыловский С.В., Криштопа С.В. "iS-DOS. Руководство пользователя". IskraSoft, Slot, С-Пб, Москва, 1993, 128 стр. Криштопа С.В. "Операционная система IS-DOS для ZX-SPECTRUM. Руководство программиста". "IskraSoft" С-Пб, "Slot" Москва, 1994, 84 стр. See also TR-DOS CP/M DISCiPLE MB02 ESX-DOS DNA OS External links , Virtual TR-DOS ATM Turbo support site Microcomputer software Disk operating systems ZX Spectrum Computing in the Soviet Union Soviet inventions

Operating System (OS)

Windows booting process The Windows booting process is the process by which the Microsoft Windows series of operating systems boots. DOS-based Windows Windows 1.x/2.x In Windows versions 1.01 to Windows 2.11, the system was loaded when WIN.COM was executed. It then loaded WIN100.BIN or WIN200.BIN and WIN100.OVL or WIN200.OVL, along with the configuration settings file WIN.INI. The default shell is the MS-DOS Executive. The modules GDI.EXE, KERNEL.EXE and USER.EXE, fonts, and the various device drivers (such as COMM.DRV, MOUSE.DRV, KEYBOARD.DRV) are incorporated in WIN100.BIN/WIN200.BIN and WIN100.OVL/WIN200.OVL. Windows 3.x/9x In Windows 3.x and 95/98/ME, the boot loader phase is handled by MS-DOS. During the boot phase, CONFIG.SYS and AUTOEXEC.BAT are executed, along with the configuration settings files WIN.INI and SYSTEM.INI. Virtual device drivers are also loaded in the startup process: they are most commonly loaded from the registry (HKLM\System\CurrentControlSet\Services\VxD) or from the SYSTEM.INI file. When all system configuration files and device drivers have been loaded, the 16-bit modules, KRNL386.EXE, GDI.EXE, and USER.EXE, are loaded, then the 32-bit DLLs (KERNEL32.DLL, GDI32.DLL, and USER32.DLL) are loaded. The 32-bit VxD message server (MSGSRV32) starts MPREXE.EXE, which is responsible for loading the network logon client (such as Client for Microsoft Networks, Microsoft Family Logon or Windows Logon). When a user is logging on to Windows, the startup sound is played, the shell (usually EXPLORER.EXE) is loaded from the [boot] section of the SYSTEM.INI file, and startup items are loaded. In all versions of Windows 9x except ME, it is also possible to load Windows by booting to a DOS prompt and typing "win". There are some command line switches that can be used with the WIN command: with the /D switch, Windows boots to safe mode, and with the /D:n switch, Windows boots to safe mode with networking. The latter switch only works properly with Windows 95. In Windows 3.1, additional options are available, such as /3, which starts Windows in 386 enhanced mode, and /S, which starts Windows in standard mode A startup sound was first added in Windows 3.0 after installing the Multimedia Extensions (MME), but not enabled by default until Windows 3.1. Windows NT In Windows NT, the boot loader is called NTLDR. It is responsible for accessing the file system on the boot drive, for starting ntoskrnl.exe and for loading boot-time device drivers into memory. Once all the Boot and System drivers have been loaded, the kernel (system thread) starts the Session Manager Subsystem (smss.exe), which in turn starts winlogon, which loads the graphical identification and authentication library. After a user has successfully logged into the machine, winlogon does the following: User and Computer Group Policy settings are applied. Startup programs are run from the following locations: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Runonce HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run HKCU\Software\Microsoft\Windows NT\CurrentVersion\Windows\Run HKCU\Software\Microsoft\Windows\CurrentVersion\Run HKCU\Software\Microsoft\Windows\CurrentVersion\RunOnce All Users ProfilePath\Start Menu\Programs\Startup\ (this path is localized on non-English versions of Windows) Current User ProfilePath\Start Menu\Programs\Startup\ (this path is localized on non-English versions of Windows) In Windows 95/98/ME, it was also possible to run a program before the user logs on by using RunServicesOnce or RunServices keys. In Windows NT, this has been replaced by the services.exe program, which is able to load a set of system services before a user logs on. Additionally, in English-language versions of Windows, the startup folder was called "StartUp" instead of "Startup" in Win9x. Due to the minimally restricted environment of these operating systems, any program can add itself to the Startup registry key or system folder. This method is frequently used by malware. Windows NT 6 The sequence of booting Windows Vista and later versions is different from any previous version of Windows that uses the NT kernel. The operating system boot loader in Vista is called winload.exe, and is invoked by Windows Boot Manager. Additionally, the GINA that has been in use with all versions of Windows NT since 3.1 has been entirely replaced by "Credential Providers". See also Linux startup process References Windows architecture Booting

Operating System (OS)

KeyKOS KeyKOS is a persistent, pure capability-based operating system for the IBM S/370 mainframe computers. It allows emulating the environments of VM, MVS, and Portable Operating System Interface (POSIX). It is a predecessor of the Extremely Reliable Operating System (EROS), and its successor operating systems, CapROS, and Coyotos. KeyKOS is a nanokernel-based operating system. In the mid-1970s, development of KeyKOS began at Tymshare, Inc., under the name GNOSIS. In 1984, McDonnell Douglas (MD) bought Tymshare. A year later MD spun off Key Logic, which bought GNOSIS and renamed it KeyKOS. References External links , Norman Hardy GNOSIS: A Prototype Operating System for the 1990s, a 1979 paper, Tymshare Inc. KeyKOS - A Secure, High-Performance Environment for S/370, a 1988 paper, Key Logic, Inc. Nanokernels Capability systems Microkernel-based operating systems

Operating System (OS)

SYS (command) In computing, sys is a command used in many operating system command-line shells and also in Microsoft BASIC. DOS, Windows, etc. SYS is an external command of Seattle Computer Products 86-DOS, Microsoft MS-DOS, IBM PC DOS, Digital Research FlexOS, IBM/Toshiba 4690 OS, PTS-DOS, Itautec/Scopus Tecnologia SISNE plus, and Microsoft Windows 9x operating systems. It is used to make an already formatted medium bootable. It will install a boot sector capable of booting the operating system into the first logical sector of the volume. Further, it will copy the principal DOS system files, that is, the DOS-BIOS (IO.SYS or IBMBIO.COM) and the DOS kernel (MSDOS.SYS or IBMDOS.COM) into the root directory of the target. Due to restrictions in the implementation of the boot loaders in the boot sector and DOS' IO system, these two files must reside in the first two directory entries and be stored at the beginning of the data area under MS-DOS and PC DOS. Depending on version, the whole files or only a varying number of sectors of the DOS-BIOS (down to only three sectors in modern issues of DOS) will have to be stored in one consecutive part. SYS will try to physically rearrange other files on the medium in order to make room for these files in their required locations. This is why SYS needs to bypass the filesystem driver in the running operating system. Other DOS derivatives such as DR-DOS do not have any such restrictions imposed by the design of the boot loaders, therefore under these systems, SYS will install a DR-DOS boot sector, which is capable of mounting the filesystem, and can then simply copy the two system files into the root directory of the target. SYS will also copy the command line shell (COMMAND.COM) into the root directory. The command can be applied to hard drives and floppy disks to repair or create a boot sector. Although an article on Microsoft's website says the SYS command was introduced in MS-DOS version 2.0, this is incorrect. SYS actually existed in 86-DOS 0.3 already. According to The MS-DOS Encyclopedia, the command was licensed to IBM as part of the first version of MS-DOS, and as such it was part of MS-DOS/PC DOS from the very beginning (IBM PC DOS 1.0 and MS-DOS 1.25). DR DOS 6.0 includes an implementation of the command. Syntax The command-syntax is: SYS [drive1:][path] drive2: Arguments: [drive1:][path] – The location of the system files drive2: – The drive to which the files will be copied Example sys a: Microsoft BASIC SYS is also a command in Microsoft BASIC used to execute a machine language program in memory. The command took the form SYS n where n is a memory location where the executable code starts. Home computer platforms typically publicised dozens of entry points to built-in routines (such as Commodore's KERNAL) that were used by programmers and users to access functionality not easily accessible through BASIC. See also List of DOS commands Disk formatting References Further reading External links MS-DOS and Windows command line sys command Open source SYS implementation that comes with MS-DOS v2.0 External DOS commands Microcomputer software Microsoft free software BASIC commands

Operating System (OS)

DoubleDOS DoubleDOS was a computer program that extended the IBM PC DOS operating system with limited multitasking capabilities. The program partitioned the computer's memory in two, running an instance of DOS in both, and allowed users to switch between the two. DoubleDOS was announced in 1984 by a firm called Softlogic Solutions, and sold for USD299. In a 1987 ad, the company offered the software for USD49.99, pitting it against competitors TopView and Windows. A review in 1986's Business Software found programs running under DoubleDOS ran considerably slower, "even when nothing is running in the other partition". See also DESQview PC-MOS/386 References DOS extenders

Operating System (OS)

Operating system advocacy Operating system advocacy is the practice of attempting to increase the public awareness and improve the perception by customers of a computer operating system. The motivation behind this may be to increase the number of users of a system, to assert the superiority of one choice over another or out of brand loyalty, pride in an operating system's abilities, or, with open source operating systems, political or philosophical reasons, or to persuade software vendors to port specific applications or device drivers to the computing platform. It is generally done in support of increasing network effects for the platform. Operating system advocacy can vary widely in tone and form, from seriously studied and researched comparisons to heated debates on mailing lists and other forums. Advocates are often normal users who devote their spare time to advocacy of their operating system of choice. Many have a deep and abiding interest in the use, design, and construction of operating systems and an emotional investment in their favorite operating system. One specific example is known as platform evangelism. Operating system advocacy can be compared to advocacy in other fields, particularly browser, editor wars, programming languages, and video game consoles, as well as the "Ford vs. Chevy" and similar debates in car culture. Usenet and other advocacy forums Due to the often emotional nature of advocacy debate and its sometimes narrow appeal to the wider user population, forums for discussion of advocacy are often separate from those for general discussion. Under the Usenet comp.os.* and comp.sys.* hierarchy, there are often *.advocacy groups devoted exclusively to advocating their respective operating systems. Some of these groups, such as comp.sys.amiga.advocacy, can remain active even after their subject OS ceases to be a market force. The Guide to the Windows newsgroups exhorts Usenet posters not to "get involved in arguments about Windows vs. OS/2 vs. Macintosh vs. NeXTSTEP except in the comp.os.ms-windows.advocacy group." Operating system advocacy discussions, on Usenet and elsewhere, have spawned a variety of jargon describing commonly seen behaviour, including "MicroDroid" and "Amiga Persecution Complex". The emotional form and negative characteristics often associated with operating system advocacy have led some to create guidelines explaining what they consider to be positive advocacy, such as the Linux Advocacy Guidelines and the Guidelines for Effective OS/2 Advocacy. Advocacy and specific operating systems FreeBSD FreeBSD is served by a mailing list specifically for advocacy discussion. Advocacy-related materials and links are provided on the FreeBSD website, including a page of logos. Linux As there are a large number of Linux distributions, there are many organizations involved in Linux advocacy, including companies directly involved in the development of distributions as well as purely advocacy-based groups, such as SEUL. Promotion takes on a wide variety of forms from Tux plush toys to t-shirts and posters, and even more unorthodox forms such as body painting and video games. macOS From the 1984 Super Bowl advertisement and "Test Drive a Macintosh" to the Apple Switch and Get a Mac advertising campaigns, Apple Computer has a long history of advocating its platform through traditional media. This also covers advocacy of the Macintosh hardware, peripherals and even lifestyle choices, with both fans and the company projecting an alternately hip, entertaining, liberating lifestyle, while negatively portraying Microsoft Windows, IBM, or other competitors as anything from awkward and dated to totalitarian and sinister Big Brother figure. Microsoft Windows Neowin.net wrote editorials opposing Windows-bashing in the media. Microsoft has attempted to boost popularity of Windows 7 with a launch party program. NetBSD Like FreeBSD, the NetBSD Foundation hosts a mailing list especially for advocacy. This mailing list is automatically archived and made accessible online. They also provide some official advocacy material, such as posters and flyers and an official "powered by" logo with a license permitting use on any product running NetBSD. OpenBSD Like FreeBSD and NetBSD, the OpenBSD project provides a mailing list specifically intended for advocacy, advocacy@openbsd.org. It was created on July 21, 1998 for discussion of user groups, stickers, shirts and the promotion of OpenBSD's image and also to host all flame-worthy discussions. As a part of its advocacy, the project also maintains a list of consulting firms and individual consultants around the world on its website and has produced a number of slogans, including "Free, Functional & Secure", "Secure by default", and "Power. Security. Flexibility." Each OpenBSD release features an original song and a variety of artwork. OS/2 Team OS/2 was a grassroots organization conceived by an IBM employee and initially joined by other IBMers which quickly spread outside IBM. Whether IBM employees or not, Team OS/2 members initially volunteered their time and passion without official sanction from or connection to IBM. Members would promote OS/2 at trade shows, conferences, fairs, and in stores, participate in operating system discussions on CompuServe, Prodigy, Fidonet and Usenet, throw parties, help users install OS/2, contact media figures to explain OS/2 and generate interest, and in general exercise creativity and initiative in helping popularize OS/2. The industry dynamics that gave rise to such passionate advocacy were multi-faceted. Perhaps the leading cause was antipathy for the idea that Microsoft could and would establish a monopoly for Windows and DOS, widely deemed as far inferior to OS/2. Additionally, many users feared that IBM, who had proven eminently capable of developing a superior PC operating system, knew very little about consumer marketing in the high-tech marketplace or establishing even a superior product as a standard in the cut-throat, get-there-first-at-any-cost arena dominated by Microsoft. Finally, the mere fact that so many copies of Windows were shipping to users (whom OS/2 advocates viewed as uncritical and uninformed), coupled with the fact that so many in the industry had so much riding on the success of OS/2, created conditions ripe for so many trying to take matters into their own hands. The only spark that was needed for this combustible situation to ignite was an example of evangelism provided by the "new IBM" - a few employees who took "empowerment" seriously, able to coordinate their efforts through participation in TEAMOS2 FORUM, an internal IBM discussion group) - and passionate supporters outside IBM who adopted the ideas and modeled the behaviors of those who were early activists within IBM. See also After the Software Wars Apple evangelist Comparison of Linux distributions Comparison of operating systems OS-tan Security-evaluated operating systems Security-focused operating systems Software wars Technical evangelist Linux adoption Comparison of user features of operating systems References External links Writing On Your Palm: Ford vs Chevy Mac, Windows War Ends in Truce Mac vs. Windows (Dead link) Computing's Holy War A simple argument for the Mac "Should I Buy OS/2 Warp?" "Why Linux?" Linux advocacy documents team? MacInSchool's list of Mac advocacy articles A site dedicated to showing why people use certain OSes "Mobile OS" Software wars

Operating System (OS)

Coherent (operating system) Coherent is a clone of the Unix operating system for IBM PC compatibles and other microcomputers, developed and sold by the now-defunct Mark Williams Company (MWC). Historically, the operating system was a proprietary product, but it became open source in 2015, released under the BSD-3-Clause license. Development Coherent was not Unix; the Mark Williams Company had no rights to either the Unix trademark or the AT&T/Bell Labs source code. In the early years of its existence, MWC received a visit from an AT&T delegation looking to determine whether MWC was infringing on AT&T Unix property. The delegation included Dennis Ritchie, who concluded that "it was very hard to believe that Coherent and its basic applications were not created without considerable study of the OS code and details of its applications." However, he also stated that: Much of the operating system was written by alumni from the University of Waterloo: Tom Duff, Dave Conroy, Randall Howard, Johann George, and Trevor John Thompson. Significant contributions were also made by people such as Nigel Bree (from Auckland, New Zealand), the later author of Ghost. Versions Coherent was originally written for the PDP-11 range of minicomputers in 1980, then ported to various early 1980s microcomputer systems including IBM PC compatibles and machines based on the Zilog Z8000 and Motorola 68000. Initially sold to OEMs, starting 1983 it was available on the consumer market from MWC directly. At this point, Coherent 2.3 offered roughly the functionality of Version 7 Unix on PC hardware, including the nroff formatter but not the BSD extensions offered by competing Unix/clone vendors; compared to its competitors, it was a small system distributed on only seven double-sided floppy disks, costing only US$500 for a license. BYTE in 1984 called Coherent a "highly compatible UNIX Version 7 lookalike". In 1985 it criticized the difficulty of installation, but stated that "as a UNIX clone, Coherent is amazingly complete ... it should be easy to port programs ... the price of $495 is a bargain". Early 1990s reviews of Coherent pointed out that the system was much smaller than other contemporary Unix offerings, as well as less expensive at US$99.95, but lacking in functionality and software support. PC Magazine called Coherent 3.0 a "time capsule" that captured the state of Unix in the late 1970s, without support for mice, LANs or SCSI disks, good for learning basic Unix programming but not for business automation. A review in the AUUG's newsletter was more positive, favorably comparing Coherent to MKS Toolkit, Minix and Xenix, and suggesting it might fill a niche as a low-end training platform. Coherent was able to run on most Intel-based PCs with Intel 8088, 286, 386, and 486 processors. Coherent version 3 for Intel-based PCs required at least a 286, Coherent version 4 for Intel-based PCs required at least a 386. Like a true Unix, Coherent was able to multitask and support multiple users. From version 4, released 1992, Coherent also had support for X11 and MGR windowing systems. Later versions of Coherent (version 4 and higher) supported features common in modern Unix-like systems, including a version of MicroEMACS, access to DOS FAT16 file systems, an optimizing C compiler, and a modified version of Taylor UUCP. The final releases of Coherent also fully supported the iBCS COFF binary standard, which allowed binary compatibility with SCO Unix applications, including WordPerfect, Lotus 1-2-3, and several Microsoft applications including QuickBASIC, Microsoft Word, and MultiPlan. The last 386 versions supported virtual memory, but not demand paging. A Zilog Z8000 port of Coherent was also used by the canceled Commodore 900 system. In 1983, NCSC (a subsidiary of Nixdorf) announced a port of Coherent to IBM mainframes, in the form of a Unix compatibility subsystem for IBM's DOS/VS and DOS/VSE and Nixdorf's Edos/VS and Edos/VSE operating systems, known as Programmer Work Station/VSE-Advanced Functions, or PWS/VSE-AF for short. The Mark Williams Company closed in 1995. On January 3, 2015, Coherent sources were released under the BSD-3-Clause license. See also Venix PC/IX References External links Andrzej Popielewicz's GNU stuff for Coherent website Coherent history archive Installation Media for Coherent 4.2.10 Coherent image for qemu Mark Williams Company Sources Virtualbox, Qemu and PCem VM's with Coherent 3.x, 4.0, 4.2.x, DDK, X11, sources... Discontinued operating systems Formerly proprietary software Lightweight Unix-like systems Software using the BSD license Unix variants X86 operating systems

Operating System (OS)

Xbox system software The Xbox system software is the operating system developed exclusively for the Xbox consoles. Across the four generations of Xbox consoles, the software has been based on a version of Microsoft Windows and incorporating DirectX features optimized for the gaming console. The user interface, the Xbox Dashboard, provides access to games, media players, and applications, and integrates with Xbox Live for online functionality. Though initial iterations of the software for the original Xbox and Xbox 360 were based on heavily modified versions of Windows, the newer consoles feature operating systems that are highly compatible with Microsoft's desktop operating systems, allowing for shared applications and ease-of-development between personal computers and the Xbox line. Common features Across all four generations of the Xbox platform, the user interface of the system software has been called the Xbox Dashboard. While its appearance and detailed functions have varied between console generations, the Dashboard has provided the user the means to start a game from the optical media loaded into the console or off the console's storage, launch audio and video players to play optical media discs, or start special applications for the Xbox such as streaming media services from third parties. The Dashboard also provides a menu of settings and configuration pages for the console that the user can adjust. The Dashboard has supported integration with the Xbox Live service since November 2002. Xbox Live provides online functionality to the Xbox, including friends list, game achievement tracking, matchmaking support for online games, in-game communications, and a digital game storefront. While some portions of the Xbox Live service are free, a subscription-tier Xbox Live Gold is generally required to play most multiplayer games on the console. Starting with the Xbox 360 and continuing through its current consoles, Microsoft has offered a means for users to opt into a beta test version of the console's system software. When first launched for the Xbox 360 in September 2010, this was called the Xbox Live Preview Program, and initially required an invitation from Microsoft after applying for the program. On the release of the Xbox One in 2014, the program was renamed to Xbox Preview Program, and Microsoft made this program open to all rather than restricting through invitation. Later in November 2016 rebranded to the Xbox Insider Program, corresponding to the similar Windows Insider program for those testing its computer operating system. With the Xbox Insider Program, testing not only included updates to the system software but upcoming game and application patches from both first and third-parties. Each iteration of the Xbox software has brought some form of backward compatibility to the newer console. On the Xbox 360, selected original Xbox console games could be played through emulation after downloading an emulation profiles to local storage. The Xbox One was not initially shipped with backward compatibility support, but was later added by January 2015 by another emulator to support selected Xbox 360 games, with hundreds of titles added over the following years. A similar emulator was developed and released in October 2017 for the Xbox One for a limited selection of original Xbox console games. Achieving Xbox One-backward compatibility on the Xbox Series X and Series S was a target goal for the newer consoles, and as such, these new consoles are fully backward compatible with all games in the Xbox One library with the exception of those requiring Kinect support. The supported list includes the Xbox and Xbox 360 games that were playable via emulation on the Xbox One. Xbox (first generation) software The original Xbox runs a custom operating system which is based on a heavily modified version of Windows 2000, an approach that Microsoft engineer Don Box called "fork and run". It exports APIs similar to those found in Microsoft Windows, such as Direct3D. While Windows 2000 was built for multitasking of multiple applications including memory paging, the Xbox console was planned to only run one application at a time, and these features were removed for the Xbox software. When loading a game, the operating system would unload itself to give all of the console's resources to the game, and then when the player left the game, the operating system would load back up again. Xbox Live support was not originally part of the system software as shipped in 2001, but added later in November 2002. While the Xbox was still being supported by Microsoft, the Xbox Dashboard was updated via Live several times to reduce cheating and add features. Microsoft released a dynamic background for its current Xbox One and Xbox Series X/S system software in May 2021 that is based on the original Xbox system software appearance. The original Xbox operating system source code was leaked in 2020. Xbox 360 software The Xbox 360 system software was also a modified version of Windows 2000, expanding beyond the original Xbox console's operating system. This would prove troublesome for Microsoft from multiple directions. For the Xbox division, it made it difficult to bring in other Microsoft applications like Internet Explorer and Silverlight which had to be modified to work on the Xbox software. For Microsoft, the separate fork of these apps for the Xbox 360 and for the versions they were developing for the mobile-based Windows CE environment became difficult to maintain. These complexities led Microsoft towards its "Windows Everywhere" approach around 2010, reviewing all the dependencies within the desktop, Xbox, and mobile versions of Windows atop the MinWin process and creating a CoreSystem that contained the basic functionality of Windows that could be ported to other systems. User interface Microsoft released the Xbox 360 console on November 22, 2005, a whole year earlier than both the Sony PlayStation 3 and Nintendo Wii. Having the advantage of the lead, Microsoft was able to experiment with various customization options for the consumer's individual consoles. The ability to customize the way the console looked with various themes to fit the front and sides of it was something very different for home console users. In system, the Xbox 360 Dashboard had the ability to have multiple profiles with password on the same console with each user being able to customize the dashboard to exactly fit their own unique style. There were premium themes available for purchase on the Xbox Live Marketplace apart from the default styles. Originally there were five tabs or sections known as the "blades" for the Xbox 360 menu, namely the Marketplace, Xbox Live, Games, Media and System. In scrolling from left to right, each section would have a different-colored background signifying its own unique area but users also had the option to change all sections to one background color as well. In 2008 however, when the gaming scene changed dramatically because of the competitions with the PlayStation 3 and the Wii, a new Xbox Dashboard titled the New Xbox Experience (NXE) was launched, which features major changes in both the user interface and other functionalities. The new user interface had a navigation system similar to that of Windows Media Center. It contained a New pop-up/in-game Live Guide, using a redesigned version of the "blades" interface, a tabbed interface that featured five "blades". Also, users were able to create personalized Avatars, essentially mini characters of themselves. Furthermore, selecting an avatar is now required by the Xbox Live service. A slightly modified version of NXE was released in 2010 alongside the Kinect as to provide support for motion-sensing controls of the Dashboard. A full reworking of the interface was released in late 2011 based on the Metro design inspired by Windows Phone. The many enhancements that were included with this update pushed the system to a more modernized interface and improved features that pushed the envelope for social gaming and media. Multimedia features While the Xbox 360 console is primarily designed to play games just like other video game consoles, it can be used as a media player too. Similar to the PlayStation 3 from Sony, Xbox 360 has media center capabilities built in, so it is relatively easy to set up. With the Xbox 360 users can also copy videos directly to the hard drive, or play via a USB stick. There are two ways to watch videos on Xbox 360. The first is to download videos from the Xbox Live Marketplace. Some of these videos are available for free while others have to be paid. Microsoft is in control of what videos are available through the Xbox Live Marketplace. The second is to stream videos from a Windows Media Center PC by using Xbox 360 as a Media Center Extender. In this way users are in control of what videos they want to watch, however there are restrictions on what kind of video they can play back. More specifically, it only supports playback of DVR-MS, MPEG-1, MPEG-2 and WMV videos. Every Xbox 360 can play DVD movies out of the box using the built-in DVD drive, with no additional parts necessary, although the user may control everything with an optional remote. There are other improvements to the experience on the Xbox 360 over the original Xbox too, including the ability to upscale the image so it will look better. Progressive scan is another feature of the DVD output in the Xbox 360 that produces smoother output when playing movies on televisions that support high definition, although using a dedicated DVD player would offer even more features and sound quality. Updates The first version of the Xbox 360 system software was 2.0.1888.0, released on November 22, 2005, as shipped in the original Xbox 360 consoles, although the version numbered "2.0" was available at product launch. Over the course of next a few years saw the continuous updates of the system software. While early updates such as version 2.0.4532.0 released on October 31, 2006 added support for 1080p video output and the external HD DVD drive attachment, version 2.0.7357.0 released on November 19, 2008 was the first major upgrade of the system software, titled the New Xbox Experience that had added many new features, including a completely redesigned GUI. It included changes in the menu system, featuring a more 3-dimensional visual style with more options and sections, new sound effects (menus only, notification sounds remain the same), support for 1440×900 and 1680×1050 16:10 resolutions (letter-boxed) over VGA, HDMI and when using DVI, as well as the abilities to preview themes before setting them, to disable notifications (new messages, chat requests, etc.) or mute the notification sound, and to change to QWERTY keyboard in place of alphabetical keyboard. Subsequent system software updates continued to add new features or make other changes, including bug fixes. An example of the new features introduced in version 2.0.8498.0 released on August 11, 2009 was the addition of Display Discovery to allow console to override factory settings for HDTV resolutions and refresh rates as well as discovering the best possible resolution and refresh rates that the HDTV is capable of displaying (Selected HDTVs). Version 2.0.12611.0, released on November 1, 2010, three days before the release of the Kinect, also added features such as the ability to install game updates to the HDD (select games only) and a visual refresh to incorporate elements of Microsoft's Metro design style. It also featured a new boot screen animation with redesigned Xbox 360 orb and ribbons. New anti-piracy 2.5 scheme to newly released games was also added in this version, later updated to anti-piracy 2.6 in the version 2.0.13599.0 released on July 19, 2011. Version 2.0.14699.0 released on December 6, 2011 introduced a redesigned interface. The releases after the version 2.0.16197.0 released October 16, 2012 were minor, consisting of bug fixes, or as a mandatory updates preparing for subsequent growth of the service. On June 15, 2020, the dashboard advertisements were removed via a server-side update. Xbox One and Xbox Series X/S software System The Xbox One console system software contains a heavily modified Hyper-V hypervisor (known as NanoVisor) as its host OS and two partitions. One of the partitions, the "Exclusive" partition is a custom virtual machine (VM) for games; the other partition, the "Shared" partition is a custom VM for running multiple apps including the OS. As part of its ongoing "Windows Everywhere" approach, Microsoft revamped the operating system in the Xbox One to be closer to its current Microsoft Windows products as to provide greater compatibility between personal computers and the Xbox line. The OS was based on Windows 8 Core at the Xbox One launch in 2013. The UI maintained the same "Metro" design that had been used in the last Xbox 360 update, and which resembled the desktop Windows 8 interface. In November 2015, Microsoft released the "New Xbox One Experience" which replaced the base system with Windows 10 Core, allowing Universal Windows Platform apps to be available on Xbox One. According to the current head of Microsoft's Gaming division, Phil Spencer, "The importance of entertainment and games to the Windows ecosystem has become really prevalent to the company". The program that Microsoft launched allows developers to build a single app that can run on a wide variety of devices, including personal computers and Xbox One video game consoles. According to Polygon, Microsoft removed the distinction between Xbox One and Windows PC, and the software has been called "Windows 10 on Xbox One". Since 2016, all Xbox One consoles could be updated to include a development kit for universal Windows applications on Xbox One, with official support for the platform and Cortana coming in summer 2016. As Microsoft continued to refine Windows 10 with the Fluent Design System, the Xbox One interface was also modified to reflect these changes by 2017. Microsoft has since continued to refine this interface to add and remove integrated features, such as inclusion of Xbox Game Pass support and removal of Cortana voice commands. Ahead of the release of the Xbox Series X and Series S consoles in November 2020, Microsoft updated the Xbox One software to reflect changes in the Dashboard that would also be present in the newer consoles. This included improved performance in some of the storefront features and readability improvements to the interface, which were also propagated across Xbox Game Pass and mobile apps. User interface The system software's interface uses a geometrical placement of squares and rectangular items that scrolls as a continuous vertical line, using the Metro design language that is also seen in Windows 8, Windows 10, and other Microsoft products. By default, the dashboard is divided into "Home", "Community", "Mixer", "Game Pass" and "Store" sections; the "Home" section contains a recent apps and games list. The "Community" section allows users to view their friends' in-game activities and captures, post status updates, as well as view trending content. The "Mixer" section shows an overview on streams on Microsoft's own Mixer service, while the "Store" section serves as a portal to the games, video, music, and app marketplaces. In general, the top level menu of the Xbox One feels a lot less cluttered than the Xbox 360's dashboard. For example, the friends tab has been removed and replaced with a dedicated app that users can load up to see what their connections are doing. There are a couple of columns for settings options and an area for "pinned" favorites, a "main" screen showing current and recent apps and games that the user played or used, and a small "What's New" section highlighting some recently added content. In total, the interface is very clean and sparse. Microsoft also introduced a new way to multitask called Snap, which allows Xbox One users to open multiple panes in a single window. When Microsoft upgraded the Windows 8-based Core to a Windows 10-based one, they made a tour of the new user interface up on Xbox Wire, promising faster, easier navigation, improved community features and, the return of Xbox Avatars. The main feature on the home screen is a list of the most recently played games. Selecting any given title will give users more information about announcements, achievements, social activity and so forth. It is also more focused on the actual games they are playing, which is part and parcel of the company's new direction under Phil Spencer, the current head of Microsoft's Xbox division. Multimedia features While like other video game consoles the Xbox One is primarily designed for playing games, it is more than a game console. It is an entertainment hub for games, television, music, and videos. Mainly the console focuses on functionality and entertainment as a whole. At Gamescom 2014 Microsoft unveiled a new plan to remedy this and make earnest on the Xbox One's label as the "all-in-one entertainment" solution by way of expanding its media support. The Xbox One's media player is quite similar to the Xbox 360's playback suite in terms of form and function, however the newer console now supports more than 30 formats including the MKV container and GIF files. The Xbox One console also does some unique things. For example, its owners can control their television broadcasts using the device, as well as use it as a functioning DVR. Apart from streaming music and videos via Play (Charms > Devices > Play), there is also a networked approach. There are two primary ways to do this. The first is to stream media from a computer or tablet, and the second is to play it directly off of a USB flash drive. The advantage of this method over the Play system is that users can do it all from wherever they sit via the Xbox One, instead of sending the video from a PC to their console. Aside from multimedia files, Xbox One plays CDs, DVDs and Blu-ray Discs, and it also comes with DLNA and MKV support, which means that downloaded video files can be streamed via the PC or transported via external hard drive and USBs. Meanwhile, the interactive TV Guide allows users to turn on and control a television with their voice. Furthermore, the system comes with a comprehensive range of applications related to multimedia features. In the United States, video channels include Amazon Instant Video, Crackle, Hulu Plus and Netflix. Microsoft announced that the Xbox One was awarded for its multimedia capabilities at the 66th Annual Technology & Engineering Emmy Awards in early 2015, and the prize was given for the Xbox One's television-on-demand functions. Updates Microsoft aims to release frequent updates to the Xbox One console, mainly containing new or improved features and faster installation and loading times for games and apps. Along with introducing improvements and fixes for native console apps and software, the monthly updates to the Xbox One system software introduce major features that are voted on or requested by the community, though some months have included more than one update. Starting in February 2014, beta releases of updates are tested before going live to check for unwanted bugs and stability. The following table lists major updates to the Xbox One and Xbox Series X/S system software. References External links What’s new: Xbox system updates Xbox Consoles Game console operating systems Software version histories Software Windows 10 Xbox One software Proprietary operating systems

Operating System (OS)

Windows Vista I/O technologies Windows Vista introduced a number of new I/O functions to the Microsoft Windows line of operating systems. They are intended to shorten the time taken to boot the system, improve the responsiveness of the system, and improve the reliability of data storage. I/O subsystem Vista modifies the behavior of asynchronous I/O operations. With the new asynchronous I/O APIs, a thread, different from the one that issued the I/O request, can be notified when the operation completes. With this, a single thread can issue all the I/O requests, and then switch to a different worker thread. If this thread is the one that handles the data after the I/O request completes, then a thread-switch, which causes a performance hit, may be avoided. Windows Vista also introduces synchronous I/O cancellation. During a synchronous I/O request, the application is blocked until the request is serviced or fails. In Windows Vista the application may issue a cancellation request. Applications that cancel the operation on user feedback may prefer to enable user feedback during the time the issuing thread is suspended for usability. Windows Vista also implements I/O scheduling as prioritized I/O. Disk I/O requests in Windows Vista are assigned priorities; a higher priority request is given preferential treatment, over a request that has a lower priority, during the execution of the request. Windows Vista defines five priority classes – Very Low, Low, Normal, High and Critical. By default I/O requests are assigned Normal priority. Windows Vista also allows reservation of bandwidth on a per-application basis during disk access; this aims to guarantee the required throughput rate to the application when it accesses the disk. Both these features are used by Windows Media Player with respect to media playback. Disk Defragmenter, SuperFetch, Windows Defender, Windows Search, and applications that run at startup all use prioritized I/O. Prior to Windows Vista, all I/O requests were capped at 64 KB; thus larger operations had to be completed in chunks. In Windows Vista, there is no limit on the size of I/O requests. This means an entire I/O operation can be completed by issuing fewer requests, which in turn may lead to higher performance. Windows Explorer and the Command Prompt's copy command have been modified to issue 1 MB requests. ReadyBoost ReadyBoost, makes PCs running Windows Vista more responsive by using flash memory on a USB drive (USB 2.0 or 3.0 only), SD card, Compact Flash, or other form of flash memory, in order to boost system performance. When such a device is plugged in, the Windows Autoplay dialog offers an additional option to use it to speed up the system; an additional "ReadyBoost" tab is added to the drive's properties dialog where the amount of space to be used can be configured. Windows ReadyBoost is also available for Windows 7 and Windows 10. Most flash memory devices are formatted in the FAT32 format. This will need to be changed if one wants to properly utilize a larger flash device for ReadyBoost. But if one activates ReadyBoost using Windows Autoplay reformatting the device will become impossible until ReadyBoost for that device is disabled. ReadyDrive ReadyDrive (codenamed Piton) is a feature of Windows Vista that enables Windows Vista computers equipped with a hybrid drive or other flash memory caches (such as Intel Turbo Memory) to boot up faster, resume from hibernation in less time, and preserve battery power. Hybrid hard drives are a type of hard disk that integrates non-volatile flash memory with a traditional hard drive. The drive-side functionality is expected to be standardized in ATA-8. When a hybrid hard drive is installed in a Windows Vista machine, the operating system will display a new "NV Cache" property tab as part of the drive's device properties within the Device Manager. It was reported in eWeek that the technology is not being utilized to full extent due to lack of hybrid drive-specific drivers for the hybrid drives and instead delegated the job to the device manufacturers. However, Microsoft rebuffed the suggestion that it was not providing specialized drivers for hybrid systems. Also, in June 2006, David Morgenstern wrote an article for eWeek suggesting that ReadyDrive might sacrifice data integrity for speed and battery savings. Documentation from Microsoft, however, claims that a copy of the data is always maintained on the hard disk, so there is no question of data loss even if the flash cache fails. SuperFetch SuperFetch is a technology that pre-loads commonly used applications into memory to reduce their load times. It is based on the "prefetcher" function in Windows XP. SuperFetch attempts to load commonly used libraries and application components into memory before they are required. It does so by continually analyzing application behavior and usage patterns, e.g. what applications are typically used in the morning after logon. The cache memory is marked with low priority, meaning that if another process needs the memory, it will be given up. By default, the necessary files are loaded into main memory, but using a feature called ReadyBoost, Windows Vista and Windows 7 can use alternative storage such as USB flash drives, thereby freeing up main memory. Although hard disks usually have higher sequential data transfer rates, flash drives can be faster for small files or non-sequential I/O because of their short random seek times. ReadyBoot is a feature that complements SuperFetch by analysing only core boot processes (such as drivers) in order to speed up a computer' startup. Offline Files Offline Files is a feature of Windows, introduced in Windows 2000, which maintains a client-side cache of files shared over a network. It locally caches shared files marked for offline access, and uses the cached copy whenever the network connection to the remote files is interrupted. Windows Vista Business, Enterprise and Ultimate editions contain significant improvements to Offline Files. Beginning with Windows Vista, whenever the connection is restored, all open file handles to the cached copy are redirected to the remote version, without waiting for the cached files to be synchronized. This transition from online to offline and back is transparent to the clients using the file. The local copy is automatically synchronized with the remote copy, to reflect the changes made on either copy of the file. The file caching and sync algorithm has also been completely rewritten to determine the differences faster. When synchronizing the changes in the cached copy to the remote version, the Bitmap Differential Transfer protocol is used so that only the changed blocks in the cached version are transferred. This also improves support for caching large files. The entire file is still downloaded when retrieving changes from the remote copy. Files are synchronized on a per-share basis and encrypted on a per-user basis and users can force Windows to work in offline mode or online mode through the Work Offline/Online button in Explorer, or sync manually from the Sync Center. Sync Center can also report sync errors and resolve sync conflicts. The property page for any file or folder has an Offline Files tab that provides status and allows control of the offline status of the file or folder. Moreover, even if a single file is unavailable, other files in the same share and other shares are available as the transition is now at the share level instead of server level. Offline Files are configurable through Group Policy and provide better interoperability with DFS. Also, a comprehensive Offline Files management API is available via COM objects and scriptability through WMI. Windows Vista also supports "ghosting" of online files and folders. When users make only a few files from a directory available offline, Windows Vista creates ghosted entries of the remaining unavailable items to preserve the online context. Offline Files also feature slow-link mode which when enabled through Group Policy, always reads from and writes to the local cache to improve performance over a slow network connection. It is also possible in Windows Vista to specify a limit for the total size of the local cache and another sub-limit for the space used by automatically cached files. Manually cached files are never removed from the local cache even if the cache limit is reached. In Windows XP, Offline Files could not be enabled when Fast User Switching was enabled. This restriction applied because Offline Files were synchronized at log off and Fast User Switching does not completely log off users. In Windows Vista, this restriction no longer applies as Offline Files runs as a Windows service that performs synchronization for the user at opportune times such as logon and offline to online transitions. Synchronization does not occur continuously in the background, nor does it occur at log off. Transactional NTFS Transactional NTFS (abbreviated TxF) brings the concept of atomic transactions to the NTFS file system, allowing Windows application developers to write file output routines that are guaranteed to either completely succeed or completely fail. Transactional NTFS allows for files and directories to be created, renamed, and deleted atomically. Using a transaction ensures correctness of operation; in a series of file operations (done as a transaction), the operation will be committed if all the operations succeed. In case of any failure, the entire operation will roll back and fail. Shadow Copy A number of Microsoft Windows components have been updated to make use of Shadow Copy. The Backup and Restore Center in Windows Vista and later performs block-based backups when doing full system backups. The file backup feature also uses shadow copy but stores files inside ZIP files. Beginning with Windows Vista, Shadow Copy is also used by the System Protection component which creates and maintains periodic copies of system and user data on the same local volume (similar to the Shadow Copies for Shared Folders feature in Windows Server) but allows it to be locally accessed by System Restore. System Restore allows reverting to an entire previous set of shadow copies called a Restore point. Prior to Windows Vista, System Restore was based on a file-based filter that watched changes for a certain set of file extensions, and then copied files before they were overwritten. Additionally, a property sheet shell extension called Previous Versions allows restoring individual files or folders locally from the restore point, as they existed at the time of the snapshot, thus retrieving an earlier version of a file or recovering a file deleted by mistake. The shadow copy is not created every time a file is changed; backup copies are created automatically once per day, or manually when triggered by the backup utility or installer applications which create a restore point. The "Previous Versions" feature is available in the Business, Enterprise, and Ultimate editions of Windows Vista. Folder redirection Windows Vista introduces the ability to independently redirect up to 10 user profile sub-folders to a network location. There is also a Management Console snap-in in Windows Vista to allow users to configure Folder Redirection for clients running Windows Vista, Windows XP, and Windows 2000. exFAT Windows Vista Service Pack 1 introduced support for the exFAT file system. See also Features new to Windows Vista BitLocker Drive Encryption Protected Media Path ACID References Windows Vista Microsoft application programming interfaces Windows NT architecture

Operating System (OS)

Multiuser DOS Multiuser DOS is a real-time multi-user multi-tasking operating system for IBM PC-compatible microcomputers. An evolution of the older Concurrent CP/M-86, Concurrent DOS and Concurrent DOS 386 operating systems, it was originally developed by Digital Research and acquired and further developed by Novell in 1991. Its ancestry lies in the earlier Digital Research 8-bit operating systems CP/M and MP/M, and the 16-bit single-tasking CP/M-86 which evolved from CP/M. When Novell abandoned Multiuser DOS in 1992, the three master value-added resellers (VARs) DataPac Australasia, Concurrent Controls and Intelligent Micro Software were allowed to take over and continued independent development into Datapac Multiuser DOS and System Manager, CCI Multiuser DOS, and IMS Multiuser DOS and REAL/32. The FlexOS line, which evolved from Concurrent DOS 286 and Concurrent DOS 68K, was sold off to Integrated Systems, Inc. (ISI) in July 1994. Concurrent CP/M-86 The initial version of CP/M-86 1.0 (with BDOS 2.x) was adapted and became available to the IBM PC in 1982. It was commercially unsuccessful as IBM's PC DOS 1.0 offered much the same facilities for a considerably lower price. Like PC DOS, CP/M-86 did not fully exploit the power and capabilities of the new 16-bit machine. It was soon supplemented by an implementation of CP/M's multitasking 'big brother', MP/M-86 2.0, since September 1981. This turned a PC into a multiuser machine capable of supporting multiple concurrent users using dumb terminals attached by serial ports. The environment presented to each user made it seem as if they had the entire computer to themselves. Since terminals cost a fraction of the then-substantial price of a complete PC, this offered considerable cost savings, as well as facilitating multi-user applications such as accounts or stock control in a time when PC networks were rare, very expensive and difficult to implement. CP/M-86 1.1 (with BDOS 2.2) and MP/M-86 2.1 were merged to create Concurrent CP/M-86 3.0 (also known as CCP/M-86) with BDOS 3.0 in late 1982. Kathryn Strutynski, the project manager for CP/M-86, was also the project manager for Concurrent CP/M-86. One of its designers was Francis "Frank" R. Holsworth. Initially, this was a single-user operating system supporting true multi-tasking of up to four (in its default configuration) CP/M-86 compatible programs. Like its predecessors it could be configured for multi-processor support (see e.g. Concurrent CP/M-86/80) and also added "virtual screens" letting an operator switch between the interactions of multiple programs. Later versions supported dumb terminals and so could be deployed as multiuser systems. Concurrent CP/M-86 3.1 (BDOS 3.1) shipped on 21 February 1984. Adaptations Concurrent CP/M-86 with Windows In February 1984 Digital Research also offered a version of Concurrent CP/M-86 with windowing capabilities named Concurrent CP/M with Windows for the IBM Personal Computer and Personal Computer XT. Concurrent CP/M-86/80 This was an adaptation of Concurrent CP/M-86 for the LSI-M4, LSI Octopus and CAL PC computers. These machines had both 16-bit and 8-bit processors, because in the early days of 16-bit personal computing, 8-bit software was more available and often ran faster than the corresponding 16-bit software. Concurrent CP/M-86/80 allowed users to run both CP/M (8-bit) and CP/M-86 (16-bit) applications. When a command was entered, the operating system ran the corresponding application on either the 8-bit or the 16-bit processor, depending on whether the executable file had a .COM or .CMD extension. It emulated a CP/M environment for 8-bit programs by translating CP/M system calls into CP/M-86 system calls, which were then executed by the 16-bit processor. Concurrent DOS In August 1983, Bruce Skidmore, Raymond D. Pedrizetti, Dave Brown and Gordon Edmonds teamed up to create PC-MODE, an optional module for Concurrent CP/M-86 3.1 (with BDOS 3.1) to provide basic compatibility with PC DOS 1.1 (and MS-DOS 1.1). This was shown publicly at COMDEX in December 1983 and shipped in March 1984 as Concurrent DOS 3.1 (a.k.a. CDOS with BDOS 3.1) to hardware vendors. Simple DOS applications, which did not directly access the screen or other hardware, could be run. For example, although a console program such as PKZIP worked perfectly and offered more facilities than the CP/M-native ARC archiver, applications which performed screen manipulations, such as the WordStar word processor for DOS, would not, and native Concurrent CP/M (or CP/M-86) versions were required. While Concurrent DOS 3.1 up to 4.1 had been developed in the US, OEM adaptations and localizations were carried out by DR Europe's OEM Support Group in Newbury, UK, since 1983. Digital Research positioned Concurrent DOS 4.1 with GEM as alternative for IBM's TopView in 1985. Concurrent PC DOS Concurrent DOS 3.2 (with BDOS 3.2) in 1984 was compatible with applications for CP/M-86 1.x, Concurrent CP/M-86 3.x and PC DOS 2.0. It was available for many different hardware platforms. The version with an IBM PC compatible BIOS/XIOS was named Concurrent PC DOS 3.2. Kathryn Strutynski was the product manager for Concurrent PC DOS. Concurrent DOS 68K and FlexOS 68K Efforts being part of a cooperation with Motorola since 1984 led to the development of Concurrent DOS 68K in Austin, Texas, as a successor to CP/M-68K written in C. One of its main architects was Francis "Frank" R. Holsworth (using siglum FRH). Concurrent DOS 68K 1.0 became available for OEM evaluation in early 1985. The effort received considerable funding worth several million dollars from Motorola and was designed for their 68000/68010 processors. Like the earlier GEMDOS system for 68000 processors it initially ran on the Motorola VME/10 development system. Concurrent DOS 68K 1.20/1.21 was available in April 1986, offered for about to OEMs. This system evolved into FlexOS 68K in late 1986. Known versions include: Concurrent DOS 68K 1.0 (1985) Concurrent DOS 68K 1.1 Concurrent DOS 68K 1.20 (April 1986, 1986-05-27) Concurrent DOS 68K 1.21 (1986) Concurrent DOS 286 and FlexOS 286 In parallel to the Concurrent DOS 68K effort, Digital Research also previewed Concurrent DOS 286 in cooperation with Intel in January 1985. This was based on MP/M-286 and Concurrent CP/M-286, on which Digital Research had worked on since 1982. Concurrent DOS 286 was a complete rewrite in the C language based on a new system architecture with dynamically loadable device drivers instead of a static BIOS or XIOS. One of its main architects was Francis "Frank" R. Holsworth. The operating system would function strictly in 80286 native mode, allowing protected mode multi-user, multitasking operation while running 8086 emulation. While this worked on the B-1 step of prototype chip samples, Digital Research, with evaluation copies of their operating system already shipping in April, discovered problems with the emulation on the production level C-1 step of the processor in May, which would not allow Concurrent DOS 286 to run 8086 software in protected mode. The release of Concurrent DOS 286 had been scheduled for late May, but was delayed until Intel could develop a new version of the chip. In August, after extensive testing E-1 step samples of the 80286, Digital Research said that Intel had corrected all documented 286 errata, but that there were still undocumented chip performance problems with the prerelease version of Concurrent DOS 286 running on the E-1 step. Intel said that the approach Digital Research wished to take in emulating 8086 software in protected mode differed from the original specifications; nevertheless they incorporated into the E-2 step minor changes in the microcode that allowed Digital Research to run emulation mode much faster (see LOADALL). These same limitations affected FlexOS 286 version 1.x, a reengineered derivation of Concurrent DOS 286, which was developed by Digital Research's new Flexible Automation Business Unit in Monterey, California, since 1986. Later versions added compatibility with PC DOS 2.x and 3.x. Known versions include: Concurrent DOS 286 1.0 (1985) Concurrent DOS 286 1.1 (1986-01-07) Concurrent DOS 286 1.2 (1986) FlexOS 286 1.3 (November 1986) FlexOS 286 1.31 (May 1987) Concurrent DOS XM and Concurrent DOS 386 The OEM Support Group was relocated into Digital Research's newly created European Development Centre (EDC) in Hungerford, UK in 1986, which started to take over further development of the Concurrent DOS family since Concurrent DOS 4.11, including siblings like DOS Plus and successors. Developed in Hungerford, UK, versions 5 and 6 (Concurrent DOS XM, with XM standing for Expanded Memory) could bank switch up to 8 MB of EEMS to provide a real-mode environment to run multiple CP/M-86 and DOS programs concurrently and support up to three users (one local and up to two hooked up via serial terminals). In 1987, Concurrent DOS 86 was rewritten to become Concurrent DOS 386, still a continuation of the classical XIOS & BDOS architecture. This ran on machines equipped with the Intel 80386 and later processors, using the 386's hardware facilities for virtualizing the hardware, allowing most DOS applications to run unmodified under Concurrent DOS 386, even on terminals. The OS supported concurrent multiuser file access, allowing multiuser applications to run as if they were on individual PCs attached to a network server. Concurrent DOS 386 allowed a single server to support a number of users on dumb terminals or inexpensive low-specification PCs running terminal emulation software, without the need for expensive workstations and then-expensive network cards. It was a true multiuser system; several users could use a single database with record locking to prevent mutual interference. Concurrent DOS 6.0 represented also the starting point for the DR DOS family, which was carved out of it. Known versions include: DR Concurrent PC DOS XM 5.0 (BDOS 5.0) DR Concurrent DOS XM 5.0 (BDOS 5.0, October 1986) DR Concurrent DOS XM 5.1 (BDOS 5.1?, January 1987) DR Concurrent DOS XM 5.2 (BDOS 5.2?, September 1987) DR Concurrent DOS XM 6.0 (BDOS 6.0, 1987-11-18), 6.01 (1987) DR Concurrent DOS XM 6.2 (BDOS 6.2), 6.21 DR Concurrent DOS 386 1.0 (BDOS 5.0?, 1987) DR Concurrent DOS 386 1.1 (BDOS 5.2?, September 1987) DR Concurrent DOS 386 2.0 (BDOS 6.0, 1987-11-18), 2.01 DR Concurrent DOS 386 3.0 (BDOS 6.2, December 1988, January 1989), 3.01 (1989-05-19), 3.02 (1989) Concurrent PC DOS XM 5.0 emulated IBM PC DOS 2.10, whereas Concurrent DOS XM 6.0 and Concurrent DOS 386 2.0 were compatible with IBM PC DOS 3.30. Adaptations Known CCI Concurrent DOS adaptations by Concurrent Controls, Inc. include: CCI Concurrent DOS 386 1.12 (BDOS 5.0?, October 1987) CCI Concurrent DOS 386 2.01 (BDOS 6.0?, May 1988) CCI Concurrent DOS 386 3.01 (BDOS 6.2?, March 1989) CCI Concurrent DOS 386 3.02 (April 1990) CCI Concurrent DOS 386 3.03 (March 1991) CCI Concurrent DOS 386 3.04 (July 1991) aka "CCI Concurrent DOS 4.0" CCI Concurrent DOS 3.05 R1 (1992-02), R2 (1992), R3+R4 (1992), R5+R6 (1992), R7+R8 (1993), R9+R10 (1993), R11 (August 1993) CCI Concurrent DOS 3.06 R1 (December 1993), R2+R3 (1994), R4+R5+R6 (1994), R7 (July 1994) CCI Concurrent DOS 3.07 R1 (March 1995), R2 (1995), R3 (1996), R4 (1996), R5 (1997), R6 (1997), R7 (June 1998) CCI Concurrent DOS 3.08 CCI Concurrent DOS 3.10 R1 (2003-10-05) Other adaptations include: Apricot Concurrent DOS 386 2.01 (1987) for Apricot Quad Version Level 4.3 Multiuser DOS Later versions of Concurrent DOS 386 incorporated some of the enhanced functionality of DR's later single-user PC DOS clone DR DOS 5.0, after which the product was given the more explanatory name "Multiuser DOS" (a.k.a. MDOS), starting with version 5.0 (with BDOS 6.5) in 1991. Multiuser DOS suffered from several technical limitations that restricted its ability to compete with LANs based on PC DOS. It required its own special device drivers for much common hardware, as PC DOS drivers were not multiuser or multi-tasking aware. Driver installation was more complex than the simple PC DOS method of copying the files onto the boot disk and modifying CONFIG.SYS appropriately it was necessary to relink the Multiuser DOS kernel (known as a nucleus) using the SYSGEN command. Multiuser DOS was also unable to use many common PC DOS additions such as network stacks, and it was limited in its ability to support later developments in the PC-compatible world, such as graphics adaptors, sound cards, CD-ROM drives and mice. Although many of these were soon rectified for example, graphical terminals were developed, allowing users to use CGA, EGA and VGA software it was less flexible in this regard than a network of individual PCs, and as the prices of these fell, it became less and less competitive, although it still offered benefits in terms of management and lower total cost of ownership. As a multi-user operating system its price was higher than a single-user system, of course, and it required special device drivers, unlike single-user multitasking DOS add-ons such as Quarterdeck's DESQview. Unlike MP/M, it never became popular for single-user but multitasking use. When Novell acquired Digital Research in 1991 and abandoned Multiuser DOS in 1992, the three Master VARs DataPac Australasia, Concurrent Controls and Intelligent Micro Software were allowed to license the source code of the system to take over and continue independent development of their derivations in 1994. Known versions include: DR Multiuser DOS 5.00 (1991), 5.01 Novell DR Multiuser DOS 5.10 (1992-04-13), 5.11 Novell DR Multiuser DOS 5.13 (BDOS 6.6, 1992) All versions of Digital Research and Novell DR Multiuser DOS reported themselves as "IBM PC DOS" version 3.31. Adaptations DataPac Australasia Known versions by DataPac Australasia Pty Limited include: Datapac Multiuser DOS 5.0 Datapac Multiuser DOS 5.1 (BDOS 6.6) Datapac System Manager 7.0 (1996-08-22) In 1997, Datapac was bought by Citrix Systems, Inc., and System Manager was abandoned soon after. In 2002 the Sydney-based unit was spun out into Citrix' Advanced Products Group. Concurrent Controls Known CCI Multiuser DOS versions by Concurrent Controls, Inc. (CCI) include: CCI Multiuser DOS 7.00 CCI Multiuser DOS 7.10 CCI Multiuser DOS 7.21 CCI Multiuser DOS 7.22 R1 (September 1996), R2 (1996), R3 (1997), R4 GOLD/PLUS/LITE (BDOS 6.6, 1997-02-10), R5 GOLD (1997), R6 GOLD (1997), R7 GOLD (June 1998), R8 GOLD, R9 GOLD, R10 GOLD, R11 GOLD (2000-09-25), R12 GOLD (2002-05-15), R13 GOLD (2002-07-15), R14 GOLD (2002-09-13), R15 GOLD, R16 GOLD (2003-10-10), R17 GOLD (2004-02-09), R18 GOLD (2005-04-21) All versions of CCI Multiuser DOS report themselves as "IBM PC DOS" version 3.31. Similar to SETVER under DOS, this can be changed using the Multiuser DOS utility. In 1999, CCI changed its name to Applica, Inc. In 2002 Applica Technology became Aplycon Technologies, Inc. Intelligent Micro Software, Itera and Integrated Solutions DOS 386 Professional IMS Multiuser DOS Known adaptations of IMS Multiuser DOS include: IMS Multiuser DOS Enhanced Release 5.1 (1992) IMS Multiuser DOS 5.11 IMS Multiuser DOS 5.14 IMS Multiuser DOS 7.0 IMS Multiuser DOS 7.1 (BDOS 6.7, 1994) All versions of IMS Multiuser DOS report themselves as "IBM PC DOS" version 3.31. REAL/32 Intelligent Micro Software Ltd. (IMS) of Thatcham, UK, acquired a license to further develop Multiuser DOS from Novell in 1994 and renamed their product REAL/32 in 1995. Similar to FlexOS/4690 OS before, IBM in 1995 licensed REAL/32 7.50 to bundle it with their 4695 POS terminals. IMS REAL/32 versions: IMS REAL/32 7.50 (BDOS 6.8, 1995-07-01), 7.51 (BDOS 6.8), 7.52 (BDOS 6.9), 7.53 (BDOS 6.9, 1996-04-01), 7.54 (BDOS 6.9, 1996-08-01) IMS REAL/32 7.60 (BDOS 6.9, February 1997), 7.61, 7.62, 7.63 IMS REAL/32 7.70 (November 1997), 7.71, 7.72, 7.73, 7.74 (1998) IMS REAL/32 7.80, 7.81 (February 1999), 7.82, 7.83 (BDOS 6.10) IMS REAL/32 7.90 (1999), 7.91, 7.92 ITERA IMS REAL/32 7.93 (June 2002), 7.94 (BDOS 6.13, 2003-01-31) Integrated Solutions IMS REAL/32 7.95 REAL/32 7.50 to 7.74 report themselves as "IBM PC DOS" version 3.31, whereas 7.80 and higher report a version of 6.20. LBA and FAT32 support was added with REAL/32 7.90 in 1999. On 19 April 2002, Intelligent Micro Software Ltd. filed for insolvency and was taken over by one of its major customers, Barry Quittenton's Itera Ltd. This company was dissolved on 2006-03-28. As of 2010 REAL/32 was supplied by Integrated Solutions of Thatcham, UK, but the company, at the same address, was later listed as builders. REAL/NG REAL/NG was IMS' attempt to create the "Next Generation" of REAL/32, also named "REAL/32 for the internet age". REAL/NG promised "increased range of hardware from PCs to x86 multi-processor server systems". Advertised feature list, as of 2003: Runs with Red Hat 7.3 or later version of Linux Backward compatible with DOS and REAL/32 Max 65535 virtual consoles; each of these can be a user No Linux expertise required Administration/setup/upgrade by web browser (local and remote) Supplied with TCP/IP Linux-/Windows-based terminal emulator for the number of users purchased Print and file sharing built in Drive mapping between Linux and REAL/NG servers built in User hardware support Increased performance Vastly increased TPA Multi-processor support Improved hardware support Built-in firewall support Very low cost per seat Low total cost of ownership Supplied on CD Supplied with a set of Red Hat CDs By 10 December 2003, IMS made "REALNG V1.60-V1.19-V1.12" available, which, based on the Internet Archive, seems to be the latest release. By 2005, the realng.com website was mirroring the IMS main website, and had no mention of REAL/NG, only REAL/32. Application software While the various releases of this operating system had increasing ability to run DOS programs, software written for the platform could take advantage of its features by using function calls specifically suitable for multiuser operation. It used pre-emptive multitasking, preventing badly-written applications from delaying other processes by retaining control of the processor. To this day, Multiuser DOS is supported by popular SSL/TLS libraries such as wolfSSL. The API provided support for blocking and non-blocking message queues, mutual-exclusion queues, the ability to create sub-process threads which executed independently from the parent, and a method of pausing execution which did not waste processor cycles, unlike idle loops used by single-user operating systems. Applications were started as "attached" to a console. However, if an application did not need user interaction it could "detach" from the console and run as a background process, later reattaching to a console if needed. Another key feature was that the memory management supported a "shared" memory model for processes (in addition to the usual models available to normal DOS programs). In the shared memory model the "code" and "data" sections of a program were isolated from each other. Because the "code" contained no modifiable data, code sections in memory could be shared by several processes running the same program, thereby reducing memory requirements. Programs written, or adapted, for any multitasking platform need to avoid the technique used by single-tasking systems of going into endless loops until interrupted when, for example, waiting for a user to press a key; this wasted processor time that could be used by other processes. Instead, Concurrent DOS provided an API call which a process could call to "sleep" for a period of time. Later versions of the Concurrent DOS kernel included Idle Detection, which monitored DOS API calls to determine whether the application was doing useful work or in fact idle, in which case the process was suspended allowing other processes to run. Idle Detection was the catalyst for the patented DR-DOS Dynamic Idle Detection power management feature invented in 1989 by Roger Alan Gross and John P. Constant and marketed as BatteryMAX. See also CP/M MP/M Concurrent DOS V60 FlexOS DR DOS PC DOS – IBM's OEM version of (single-user) MS-DOS MS-DOS 4.0 (multitasking) PC-MOS/386 – unrelated multitasking DOS clone VM/386 – unrelated multitasking DOS environment Virtual DOS machine Multiuser DOS Federation Timeline of operating systems List of mergers and acquisitions by Citrix References Further reading External links https://web.archive.org/web/20190401161050/http://www.imsltd.com/ former Intelligent Micro Software (IMS) website (vendors of IMS Multiuser DOS, IMS REAL/32, and REAL/NG) https://web.archive.org/web/20010515195706/http://www.lii.com/ former Logan Industries (LLI) website (IMS REAL/32 US distributor up to 2002-05-01) https://web.archive.org/web/20071213140207/http://www.conctrls.com/ former Concurrent Controls website (CCI Multiuser DOS) https://web.archive.org/web/*/https://applica.com Applica, Inc. website https://web.archive.org/web/20040412051935/http://www.aplycon.com/ former Aplycon Technologies, Inc. website CP/M variants Disk operating systems DOS variants Real-time operating systems Digital Research operating systems Novell operating systems Microcomputer software Discontinued operating systems Proprietary operating systems

Operating System (OS)

Sysop A sysop (; an abbreviation of system operator) is an administrator of a multi-user computer system, such as a bulletin board system (BBS) or an online service virtual community. The phrase may also be used to refer to administrators of other Internet-based network services. A sysop usually doesn't earn money, but donates his activity to the community. Co-sysops are users who may be granted certain admin privileges on a BBS. Generally, they help validate users and monitor discussion forums. Some co-sysops serve as file clerks, reviewing, describing, and publishing newly uploaded files into appropriate download directories. Historically, the term system operator applied to operators of any computer system, especially a mainframe computer. In general, a sysop is a person who oversees the operation of a server, typically in a large computer system. Usage of the term became popular in the late 1980s and 1990s, originally in reference to BBS operators. A person with equivalent functions on a network host or server is typically called a sysadmin, short for system administrator. Because such duties were often shared with that of the sysadmin prior to the advent of the World Wide Web, the term sysop is often used more generally to refer to an administrator or moderator, such as a forum administrator. Hence, the term sysadmin is technically used to distinguish the professional position of a network operator. See also Internet slang Jargon Jargon File Network administrator Online service provider Virtual community References Bulletin board systems Internet slang System administration

Operating System (OS)

IncludeOS IncludeOS is a minimal, open source, unikernel operating system for cloud services and IoT. IncludeOS allows users to run C++ applications in the cloud without an operating system. IncludeOS adds operating system functionality to an application allowing oneself to create a 'virtual machine' for an application. IncludeOS applications boot in tens of milliseconds and require only a few megabytes of disk and memory. Architecture The minimalist architecture of IncludeOS means that it does not have any virtual memory space. In turn, therefore, there is no concept of system calls nor user space. References External links IncludeOS on GitHub IncludeOS blog Alfred Bratterud: Deconstructing the OS: The devil’s In the side effects, CppCon 2017 presentation C++ Weekly - Ep 31 - IncludeOS Computing platforms Free software operating systems Software using the Apache license Software companies of Norway Free software programmed in C++

Operating System (OS)

Uname uname (short for unix name) is a computer program in Unix and Unix-like computer operating systems that prints the name, version and other details about the current machine and the operating system running on it. History The uname system call and command appeared for the first time in PWB/UNIX. Both are specified by POSIX. The GNU version of uname is included in the "sh-utils" or "coreutils" packages. uname itself is not available as a standalone program. The version of uname bundled in GNU coreutils was written by David MacKenzie. The command is available as a separate package for Microsoft Windows as part of the GnuWin32 project and the UnxUtils collection of native Win32 ports of common GNU Unix-like utilities. Related and similar commands Some Unix variants, such as AT&T UNIX System V Release 3.0, include the related setname program, used to change the values that uname reports. The ver command found in operating systems such as DOS, OS/2 and Microsoft Windows is similar to the uname command. Examples On a system running Darwin, the output from running uname with the -a command line argument might look like the text below: $ uname -a Darwin Roadrunner.local 10.3.0 Darwin Kernel Version 10.3.0: Fri Feb 26 11:58:09 PST 2010; root:xnu-1504.3.12~1/RELEASE_I386 i386 The following table contains examples from various versions of uname on various platforms. Within the bash shell, the variable OSTYPE contains a value similar (but not identical) to the value of . See also List of Unix commands lsb_release ver (command) Footnotes External links Unix SUS2008 utilities

Operating System (OS)

SkyOS SkyOS (Sky Operating System) is a discontinued prototype commercial, proprietary, graphical desktop operating system written for the x86 computer architecture. As of January 30, 2009 development was halted with no plans to resume its development. In August 2013, developer Robert Szeleney announced the release of a public beta on the SkyOS website. This allows public users to download a Live CD of the SkyOS operating system, for testing and to optionally install the system. History Development started in 1996 with the first version released in December 1997. Up until version 4.x the OS was freely available. Starting with beta development of SkyOS 5 in 2003, users were required to pay US$30 to get access to beta releases. SkyOS adapted new filesystem SkyFS based on OpenBFS in 2004 and its graphics subsystem was improved in 2006 with support for desktop compositing including double buffering and transparency. The OS also moved to ELF binaries then. The last beta build 6947 was released in August 2008 and there was no status update for several months. As the OS was mainly the work of one man, Robert Szeleney, there was increasing difficulty to add new device drivers. Considering lack of development under Robert Szeleney, going open source was viewed by the tech press as the best option for SkyOS. Although Szeleney tried to bypass the lack of drivers by using a new kernel based on Linux or NetBSD, and reported some progress in this regard, development has not resumed. SkyOS website disappeared in 2013 and final public build from August 2008 was released for free shortly thereafter. Features Kernel SkyOS is a Unix-like operating system with a monolithic kernel. The OS supports multiple users and symmetric multiprocessing. Graphics and GUI SkyOS has an integrated graphics subsystem with support for desktop compositing including double buffering and transparency. SkyOS GUI also allows system-wide mouse gestures. SkyFS SkyFS is a fork of the OpenBFS filesystem. SkyOS can also be run from the following filesystems: FAT32/FAT16/FAT12 ISO 9660 Fast searching SkyOS offers real-time file content query searches with multiple keywords (comparable to Beagle in Linux or Spotlight in macOS), including indexing of files and programs. Porting applications Most command-line applications that were written to be compiled with the GNU Toolchain can be ported to SkyOS with little or no modification. SkyOS contains several frameworks for creating applications (including Mono port). Ported applications include Mozilla Firefox, Mozilla Thunderbird, Nvu, GIMP and AbiWord. There was also a monetary incentive for porting applications as the SkyOS community voted for desired programs and then supported developers with donations. Reception Although SkyOS includes many interesting features, limited application and hardware support are among its weaknesses (e.g. only a few graphics cards allow 2D acceleration). Kernel and drivers updates were solely worked on by Szeleney, and because of this he was unable to keep up with new devices. This was one of the reasons the development ended for this project. In the end, the OS was not able to expand beyond a small albeit dedicated user community. Apart from a short early open source time period, the OS had a proprietary licence with a commercial model based on paid beta-testing. This led to some controversy as SkyOS developers were accused of unauthorized use of open source software. No proof of any wrongdoing was given, but the public image of the OS was tarnished nevertheless. See also List of operating systems References External links SkyOS.org—The SkyOS Homepage SkyOS.at—The SkyOS Homepage (Alternative Address) TechIMO—SkyOS Developers Interview Slashdot—Walking Through SkyOS 5.0 Beta Slashdot—Thunderbird and Firefox Ported to SkyOS OSNews.com—SkyOS, The 7th Beta and Robert Szeleney SkyOS archive and downloads Proprietary operating systems X86 operating systems 1997 software

Operating System (OS)

Osaris Osaris is a personal digital assistant (PDA) featuring the EPOC operating system (OS) distributed by Oregon Scientific. The Osaris was released in 1999, and at the time priced at to . The Osaris contains an 18.432 MHz CL-PS7111 (ARM 710) processor and is powered by two AA size batteries or an external power 6 volt AC adapter, with a 3 volt CR2032 cell providing backup power. The liquid-crystal display (LCD) is a touchscreen, backlit 320 × 200 pixels with 16 greyscale levels. There are also 10 membrane keys, 5 on each side of the LCD. The Osaris can be linked to a PC via an RS-232 link cable and IrDA (Infrared). The Osaris contains 8 MB of read-only memory (ROM), and, depending on the model, 4 MB, 8 MB or 16 MB random-access memory (RAM). The memory can also be expanded using CompactFlash. Dimensions: 170 × 90 × 20 mm Weight: c. 250 g The Osaris is the only PDA to use the EPOC release 4 operating system. It also has the distinction of being the first device to run EPOC (later renamed Symbian OS) that was not built by Psion. It is very similar in ability to the Psion Series 5. The Osaris comes with these programs preinstalled: Agenda: For appointments, things to do, birthdays, anniversaries Data: For names, addresses, or other database use Jotter: For making quick notes Time: For alarms Calc: For simple or scientific calculations World: Shows a map, world times, dialling codes Word: For writing documents, letters Sheet: For tables, spreadsheets, graphs Program: Editor for writing computer programs Personal digital assistants Personal information managers Computer-related introductions in 1999

Operating System (OS)

Eumel EUMEL (pronounced oimel for Extendable Multi User Microprocessor ELAN System and also known as L2 for Liedtke 2) is an operating system (OS) which began as a runtime system (environment) for the programming language ELAN. It was created in 1979 by Jochen Liedtke at the Bielefeld University. EUMEL initially ran on the 8-bit Zilog Z80 processor. It later was ported to many different computer architectures. More than 2000 Eumel systems shipped, mostly to schools and also to legal practices as a text processing platform. EUMEL is based on a virtual machine using a bitcode and achieves remarkable performance and function. Z80-based EUMEL systems provide full multi-user multi-tasking operation with virtual memory management and complete isolation of one process against all others. These systems usually execute ELAN programs faster than equivalent programs written in languages such as COBOL, BASIC, or Pascal, and compiled into Z80 machine code on other operating systems. One of the main features of EUMEL is that it is persistent, using a fixpoint/restart logic. This means that if the OS crashes, or the power fails, a user loses only a few minutes of work: on restart they continue working from the prior fixpoint with all program state intact fully. This is also termed orthogonal persistence. EUMEL was followed by the L3 microkernel, and later the L4 microkernel family. References Discontinued operating systems Microkernels

Operating System (OS)

Android (operating system) Android is a mobile operating system based on a modified version of the Linux kernel and other open source software, designed primarily for touchscreen mobile devices such as smartphones and tablets. Android is developed by a consortium of developers known as the Open Handset Alliance and commercially sponsored by Google. It was unveiled in November 2007, with the first commercial Android device, the HTC Dream, being launched in September 2008. Most versions of Android are proprietary. The core components are taken from the Android Open Source Project (AOSP), which is free and open-source software primarily licensed under the Apache License. When Android is actually installed on devices, ability to modify the otherwise FOSS software is usually restricted, either by not providing the corresponding source code or preventing reinstallation through technical measures, rendering the installed version proprietary. Most Android devices ship with additional proprietary software pre-installed, most notably Google Mobile Services (GMS) which includes core apps such as Google Chrome, the digital distribution platform Google Play, and associated Google Play Services development platform. Over 70 percent of Android smartphones run Google's ecosystem; some with vendor-customized user interface and software suite, such as TouchWiz and later One UI by Samsung, and HTC Sense. Competing Android ecosystems and forks include Fire OS (developed by Amazon) or LineageOS. However the "Android" name and logo are trademarks of Google which imposes standards to restrict the use of Android branding by "uncertified" devices outside their ecosystem. The source code has been used to develop variants of Android on a range of other electronics, such as game consoles, digital cameras, portable media players, PCs, each with a specialized user interface. Some well known derivatives include Android TV for televisions and Wear OS for wearables, both developed by Google. Software packages on Android, which use the APK format, are generally distributed through proprietary application stores like Google Play Store, Amazon Appstore (including for Windows 11), Samsung Galaxy Store, Huawei AppGallery, Cafe Bazaar, and GetJar, or open source platforms like Aptoide or F-Droid. Android has been the best-selling OS worldwide on smartphones since 2011 and on tablets since 2013. , it has over three billion monthly active users, the largest installed base of any operating system, and , the Google Play Store features over 3 million apps. Android 12, released on October 4, 2021, is the latest version. History Android Inc. was founded in Palo Alto, California, in October 2003 by Andy Rubin, Rich Miner, Nick Sears, and Chris White. Rubin described the Android project as having "tremendous potential in developing smarter mobile devices that are more aware of its owner's location and preferences". The early intentions of the company were to develop an advanced operating system for digital cameras, and this was the basis of its pitch to investors in April 2004. The company then decided that the market for cameras was not large enough for its goals, and five months later it had diverted its efforts and was pitching Android as a handset operating system that would rival Symbian and Microsoft Windows Mobile. Rubin had difficulty attracting investors early on, and Android was facing eviction from its office space. Steve Perlman, a close friend of Rubin, brought him $10,000 in cash in an envelope, and shortly thereafter wired an undisclosed amount as seed funding. Perlman refused a stake in the company, and has stated "I did it because I believed in the thing, and I wanted to help Andy." In 2005, Rubin tried to negotiate deals with Samsung and HTC. Shortly afterwards, Google acquired the company in July of that year for at least $50 million; this was Google's "best deal ever" according to Google's then-vice president of corporate development, David Lawee, in 2010. Android's key employees, including Rubin, Miner, Sears, and White, joined Google as part of the acquisition. Not much was known about the secretive Android Inc. at the time, with the company having provided few details other than that it was making software for mobile phones. At Google, the team led by Rubin developed a mobile device platform powered by the Linux kernel. Google marketed the platform to handset makers and carriers on the promise of providing a flexible, upgradeable system. Google had "lined up a series of hardware components and software partners and signaled to carriers that it was open to various degrees of cooperation". Speculation about Google's intention to enter the mobile communications market continued to build through December 2006. An early prototype had a close resemblance to a BlackBerry phone, with no touchscreen and a physical QWERTY keyboard, but the arrival of 2007's Apple iPhone meant that Android "had to go back to the drawing board". Google later changed its Android specification documents to state that "Touchscreens will be supported", although "the Product was designed with the presence of discrete physical buttons as an assumption, therefore a touchscreen cannot completely replace physical buttons". By 2008, both Nokia and BlackBerry announced touch-based smartphones to rival the iPhone 3G, and Android's focus eventually switched to just touchscreens. The first commercially available smartphone running Android was the HTC Dream, also known as T-Mobile G1, announced on September 23, 2008. On November 5, 2007, the Open Handset Alliance, a consortium of technology companies including Google, device manufacturers such as HTC, Motorola and Samsung, wireless carriers such as Sprint and T-Mobile, and chipset makers such as Qualcomm and Texas Instruments, unveiled itself, with a goal to develop "the first truly open and comprehensive platform for mobile devices". Within a year, the Open Handset Alliance faced two other open source competitors, the Symbian Foundation and the LiMo Foundation, the latter also developing a Linux-based mobile operating system like Google. In September 2007, InformationWeek covered an Evalueserve study reporting that Google had filed several patent applications in the area of mobile telephony. Since 2008, Android has seen numerous updates which have incrementally improved the operating system, adding new features and fixing bugs in previous releases. Each major release is named in alphabetical order after a dessert or sugary treat, with the first few Android versions being called "Cupcake", "Donut", "Eclair", and "Froyo", in that order. During its announcement of Android KitKat in 2013, Google explained that "Since these devices make our lives so sweet, each Android version is named after a dessert", although a Google spokesperson told CNN in an interview that "It's kind of like an internal team thing, and we prefer to be a little bit — how should I say — a bit inscrutable in the matter, I'll say". In 2010, Google launched its Nexus series of devices, a lineup in which Google partnered with different device manufacturers to produce new devices and introduce new Android versions. The series was described as having "played a pivotal role in Android's history by introducing new software iterations and hardware standards across the board", and became known for its "bloat-free" software with "timely ... updates". At its developer conference in May 2013, Google announced a special version of the Samsung Galaxy S4, where, instead of using Samsung's own Android customization, the phone ran "stock Android" and was promised to receive new system updates fast. The device would become the start of the Google Play edition program, and was followed by other devices, including the HTC One Google Play edition, and Moto G Google Play edition. In 2015, Ars Technica wrote that "Earlier this week, the last of the Google Play edition Android phones in Google's online storefront were listed as "no longer available for sale" and that "Now they're all gone, and it looks a whole lot like the program has wrapped up". From 2008 to 2013, Hugo Barra served as product spokesperson, representing Android at press conferences and Google I/O, Google's annual developer-focused conference. He left Google in August 2013 to join Chinese phone maker Xiaomi. Less than six months earlier, Google's then-CEO Larry Page announced in a blog post that Andy Rubin had moved from the Android division to take on new projects at Google, and that Sundar Pichai would become the new Android lead. Pichai himself would eventually switch positions, becoming the new CEO of Google in August 2015 following the company's restructure into the Alphabet conglomerate, making Hiroshi Lockheimer the new head of Android. On Android 4.4 Kit Kat, shared writing access to MicroSD memory cards has been locked for user-installed applications, to which only the dedicated directories with respective package names, located inside Android/data/, remained writeable. Writing access has been reinstated with Android 5 Lollipop through the backwards-incompatible Google Storage Access Framework interface. In June 2014, Google announced Android One, a set of "hardware reference models" that would "allow [device makers] to easily create high-quality phones at low costs", designed for consumers in developing countries. In September, Google announced the first set of Android One phones for release in India. However, Recode reported in June 2015 that the project was "a disappointment", citing "reluctant consumers and manufacturing partners" and "misfires from the search company that has never quite cracked hardware". Plans to relaunch Android One surfaced in August 2015, with Africa announced as the next location for the program a week later. A report from The Information in January 2017 stated that Google is expanding its low-cost Android One program into the United States, although The Verge notes that the company will presumably not produce the actual devices itself. Google introduced the Pixel and Pixel XL smartphones in October 2016, marketed as being the first phones made by Google, and exclusively featured certain software features, such as the Google Assistant, before wider rollout. The Pixel phones replaced the Nexus series, with a new generation of Pixel phones launched in October 2017. In May 2019, the operating system became entangled in the trade war between China and the United States involving Huawei, which, like many other tech firms, had become dependent on access to the Android platform. In the summer of 2019, Huawei announced it would create an alternative operating system to Android known as Harmony OS, and has filed for intellectual property rights across major global markets. Huawei does not currently have any plans to replace Android in the near future, as Harmony OS is designed for internet of things devices, rather than for smartphones. On August 22, 2019, it was announced that Android "Q" would officially be branded as Android 10, ending the historic practice of naming major versions after desserts. Google stated that these names were not "inclusive" to international users (due either to the aforementioned foods not being internationally known, or being difficult to pronounce in some languages). On the same day, Android Police reported that Google had commissioned a statue of a giant number "10" to be installed in the lobby of the developers' new office. Android 10 was released on September 3, 2019 to Google Pixel phones first. With scoped storage, conventional writing access to the shared internal user storage has been locked, and only app-specific directories remain accessible as usual. Files and directories outside only remain accessible through the backwards-incompatible Storage Access Framework. While these restrictions are claimed to improve user privacy, private app-specific directories already existed under /data/ since early versions of the operating system. Features Interface Android's default user interface is mainly based on direct manipulation, using touch inputs that loosely correspond to real-world actions, like swiping, tapping, pinching, and reverse pinching to manipulate on-screen objects, along with a virtual keyboard. Game controllers and full-size physical keyboards are supported via Bluetooth or USB. The response to user input is designed to be immediate and provides a fluid touch interface, often using the vibration capabilities of the device to provide haptic feedback to the user. Internal hardware, such as accelerometers, gyroscopes and proximity sensors are used by some applications to respond to additional user actions, for example adjusting the screen from portrait to landscape depending on how the device is oriented, or allowing the user to steer a vehicle in a racing game by rotating the device, simulating control of a steering wheel. Home screen Android devices boot to the home screen, the primary navigation and information "hub" on Android devices, analogous to the desktop found on personal computers. Android home screens are typically made up of app icons and widgets; app icons launch the associated app, whereas widgets display live, auto-updating content, such as a weather forecast, the user's email inbox, or a news ticker directly on the home screen. A home screen may be made up of several pages, between which the user can swipe back and forth. Third-party apps available on Google Play and other app stores can extensively re-theme the home screen, and even mimic the look of other operating systems, such as Windows Phone. Most manufacturers customize the look and features of their Android devices to differentiate themselves from their competitors. Status bar Along the top of the screen is a status bar, showing information about the device and its connectivity. This status bar can be pulled (swiped) down from to reveal a notification screen where apps display important information or updates, as well as quick access to system controls and toggles such as display brightness, connectivity settings (WiFi, Bluetooth, cellular data), audio mode, and flashlight. Vendors may implement extended settings such as the ability to adjust the flashlight brightness. Notifications Notifications are "short, timely, and relevant information about your app when it's not in use", and when tapped, users are directed to a screen inside the app relating to the notification. Beginning with Android 4.1 "Jelly Bean", "expandable notifications" allow the user to tap an icon on the notification in order for it to expand and display more information and possible app actions right from the notification. App lists An "All Apps" screen lists all installed applications, with the ability for users to drag an app from the list onto the home screen. The app list may be accessed using a gesture or a button, depending on the Android version. A "Recents" screen, also known as "Overview", lets users switch between recently used apps. The recent list may appear side-by-side or overlapping, depending on the Android version and manufacturer. Navigation buttons Many early Android OS smartphones were equipped with a dedicated search button for quick access to a web search engine and individual apps' internal search feature. More recent devices typically allow the former through a long press or swipe away from the home button. The dedicated option key, also known as menu key, and its on-screen simulation, is no longer supported since Android version 10. Google recommends mobile application developers to locate menus within the user interface. On more recent phones, its place is occupied by a task key used to access the list of recently used apps when actuated. Depending on device, its long press may simulate a menu button press or engage split screen view, the latter of which is the default behaviour since stock Android version 7. Split-screen view Native support for split screen view has been added in stock Android version 7.0 Nougat. The earliest vendor-customized Android-based smartphones known to have featured a split-screen view mode are the 2012 Samsung Galaxy S3 and Note 2, the former of which received this feature with the premium suite upgrade delivered in TouchWiz with Android 4.1 Jelly Bean. Charging while powered off When connecting or disconnecting charging power and when shortly actuating the power button or home button, all while the device is powered off, a visual battery meter whose appearance varies among vendors appears on the screen, allowing the user to quickly assess the charge status of a powered-off without having to boot it up first. Some display the battery percentage. Audio-coupled haptic effect Since stock Android version 12, released early 2021, synchronous vibration can be set to complement audio. Such feature initially existed under the name "Auto Haptic" on the Android-based 2012 Samsung Galaxy S III, released with a vendor-modified (TouchWiz) installation of Android 4.1 Jelly Bean. Applications Many, to almost all, Android devices come with preinstalled Google apps including Gmail, Google Maps, Google Chrome, YouTube, Google Play Music, Google Play Movies & TV, and many more. Applications ("apps"), which extend the functionality of devices (and must be 64-bit), are written using the Android software development kit (SDK) and, often, Kotlin programming language, which replaced Java as Google's preferred language for Android app development in May 2019, and was originally announced in May 2017. Java is still supported (originally the only option for user-space programs, and is often mixed with Kotlin), as is C++. Java or other JVM languages, such as Kotlin, may be combined with C/C++, together with a choice of non-default runtimes that allow better C++ support. The Go programming language is also supported, although with a limited set of application programming interfaces (API). The SDK includes a comprehensive set of development tools, including a debugger, software libraries, a handset emulator based on QEMU, documentation, sample code, and tutorials. Initially, Google's supported integrated development environment (IDE) was Eclipse using the Android Development Tools (ADT) plugin; in December 2014, Google released Android Studio, based on IntelliJ IDEA, as its primary IDE for Android application development. Other development tools are available, including a native development kit (NDK) for applications or extensions in C or C++, Google App Inventor, a visual environment for novice programmers, and various cross platform mobile web applications frameworks. In January 2014, Google unveiled a framework based on Apache Cordova for porting Chrome HTML 5 web applications to Android, wrapped in a native application shell. Additionally, Firebase was acquired by Google in 2014 that provides helpful tools for app and web developers. Android has a growing selection of third-party applications, which can be acquired by users by downloading and installing the application's APK (Android application package) file, or by downloading them using an application store program that allows users to install, update, and remove applications from their devices. Google Play Store is the primary application store installed on Android devices that comply with Google's compatibility requirements and license the Google Mobile Services software. Google Play Store allows users to browse, download and update applications published by Google and third-party developers; , there are more than three million applications available for Android in Play Store. , 50 billion application installations had been performed. Some carriers offer direct carrier billing for Google Play application purchases, where the cost of the application is added to the user's monthly bill. , there are over one billion active users a month for Gmail, Android, Chrome, Google Play and Maps. Due to the open nature of Android, a number of third-party application marketplaces also exist for Android, either to provide a substitute for devices that are not allowed to ship with Google Play Store, provide applications that cannot be offered on Google Play Store due to policy violations, or for other reasons. Examples of these third-party stores have included the Amazon Appstore, GetJar, and SlideMe. F-Droid, another alternative marketplace, seeks to only provide applications that are distributed under free and open source licenses. In October 2020, Google removed several Android applications from Play Store, as they were identified breaching its data collection rules. The firm was informed by International Digital Accountability Council (IDAC) that apps for children like Number Coloring, Princess Salon and Cats & Cosplay, with collective downloads of 20 million, were violating Google's policies. At the Windows 11 announcement event in June 2021, Microsoft showcased the new Windows Subsystem for Android (WSA) that will enable support for the Android Open Source Project (AOSP) and will allow users to run Android apps on their Windows desktop. File manager Since Android 6 Marshmallow, a minimalistic file manager codenamed DocumentsUI is part of the operating system's core, and based on the file selector. It is only accessible through the storage menu in the system settings. Adoptable storage Android 6.0 Marshmallow brought adoptable storage, an option to format and mount the memory card as extension of the internal storage instead of default separate portable storage. While possibly facilitating on-device file management due to files stored on both internal storage and memory card appearing in one place, adopted storage denies data recovery at technical defect and instant reuse in a different device unless reformatted. For these reasons, the major vendors Samsung and LG opted to exclude adoptable storage. Applications moved to the memory card were previously stored as .asec files inside an ".android_secure" directory. Memory management Since Android devices are usually battery-powered, Android is designed to manage processes to keep power consumption at a minimum. When an application is not in use the system suspends its operation so that, while available for immediate use rather than closed, it does not use battery power or CPU resources. Android manages the applications stored in memory automatically: when memory is low, the system will begin invisibly and automatically closing inactive processes, starting with those that have been inactive for the longest amount of time. Lifehacker reported in 2011 that third-party task-killer applications were doing more harm than good. Developer options Some settings for use by developers for debugging and power users are located in a "Developer options" sub menu, such as the ability to highlight updating parts of the display, show an overlay with the current status of the touch screen, show touching spots for possible use in screencasting, notify the user of unresponsive background processes with the option to end them ("Show all ANRs", i.e. "App's Not Responding"), prevent a Bluetooth audio client from controlling the system volume ("Disable absolute volume"), and adjust the duration of transition animations or deactivate them completely to speed up navigation. Developer options are initially hidden since Android 4.2 "Jelly Bean", but can be enabled by actuating the operating system's build number in the device information seven times. Hiding developers options again requires deleting user data for the "Settings" app, possibly resetting some other preferences. Hardware The main hardware platform for Android is ARM (the ARMv7 and ARMv8-A architectures), with x86 and x86-64 architectures also officially supported in later versions of Android. The unofficial Android-x86 project provided support for x86 architectures ahead of the official support. Since 2012, Android devices with Intel processors began to appear, including phones and tablets. While gaining support for 64-bit platforms, Android was first made to run on 64-bit x86 and then on ARM64. Since Android 5.0 "Lollipop", 64-bit variants of all platforms are supported in addition to the 32-bit variants. An unofficial experimental port of the operating system to the RISC-V architecture was released in 2021. Requirements for the minimum amount of RAM for devices running Android 7.1 range from in practice 2 GB for best hardware, down to 1 GB for the most common screen. Android supports all versions of OpenGL ES and Vulkan (and version 1.1 available for some devices). Android devices incorporate many optional hardware components, including still or video cameras, GPS, orientation sensors, dedicated gaming controls, accelerometers, gyroscopes, barometers, magnetometers, proximity sensors, pressure sensors, thermometers, and touchscreens. Some hardware components are not required, but became standard in certain classes of devices, such as smartphones, and additional requirements apply if they are present. Some other hardware was initially required, but those requirements have been relaxed or eliminated altogether. For example, as Android was developed initially as a phone OS, hardware such as microphones were required, while over time the phone function became optional. Android used to require an autofocus camera, which was relaxed to a fixed-focus camera if present at all, since the camera was dropped as a requirement entirely when Android started to be used on set-top boxes. In addition to running on smartphones and tablets, several vendors run Android natively on regular PC hardware with a keyboard and mouse. In addition to their availability on commercially available hardware, similar PC hardware-friendly versions of Android are freely available from the Android-x86 project, including customized Android 4.4. Using the Android emulator that is part of the Android SDK, or third-party emulators, Android can also run non-natively on x86 architectures. Chinese companies are building a PC and mobile operating system, based on Android, to "compete directly with Microsoft Windows and Google Android". The Chinese Academy of Engineering noted that "more than a dozen" companies were customizing Android following a Chinese ban on the use of Windows 8 on government PCs. Development Android is developed by Google until the latest changes and updates are ready to be released, at which point the source code is made available to the Android Open Source Project (AOSP), an open source initiative led by Google. The AOSP code can be found without modification on select devices, mainly the former Nexus and current Android One series of devices. The source code is, in turn, customized by original equipment manufacturers (OEMs) to run on their hardware. Android's source code does not contain the device drivers, often proprietary, that are needed for certain hardware components. As a result, most Android devices, including Google's own, ship with a combination of free and open source and proprietary software, with the software required for accessing Google services falling into the latter category. Update schedule Google announces major incremental upgrades to Android on a yearly basis. The updates can be installed on devices over-the-air. The latest major release is Android 12. The extensive variation of hardware in Android devices has caused significant delays for software upgrades and security patches. Each upgrade has had to be specifically tailored, a time- and resource-consuming process. Except for devices within the Google Nexus and Pixel brands, updates have often arrived months after the release of the new version, or not at all. Manufacturers often prioritize their newest devices and leave old ones behind. Additional delays can be introduced by wireless carriers who, after receiving updates from manufacturers, further customize Android to their needs and conduct extensive testing on their networks before sending out the upgrade. There are also situations in which upgrades are impossible due to a manufacturer not updating necessary drivers. The lack of after-sale support from manufacturers and carriers has been widely criticized by consumer groups and the technology media. Some commentators have noted that the industry has a financial incentive not to upgrade their devices, as the lack of updates for existing devices fuels the purchase of newer ones, an attitude described as "insulting". The Guardian complained that the method of distribution for updates is complicated only because manufacturers and carriers have designed it that way. In 2011, Google partnered with a number of industry players to announce an "Android Update Alliance", pledging to deliver timely updates for every device for 18 months after its release; however, there has not been another official word about that alliance since its announcement. In 2012, Google began de-coupling certain aspects of the operating system (particularly its central applications) so they could be updated through the Google Play store independently of the OS. One of those components, Google Play Services, is a closed-source system-level process providing APIs for Google services, installed automatically on nearly all devices running Android 2.2 "Froyo" and higher. With these changes, Google can add new system functions and update apps without having to distribute an upgrade to the operating system itself. As a result, Android 4.2 and 4.3 "Jelly Bean" contained relatively fewer user-facing changes, focusing more on minor changes and platform improvements. HTC's then-executive Jason Mackenzie called monthly security updates "unrealistic" in 2015, and Google was trying to persuade carriers to exclude security patches from the full testing procedures. In May 2016, Bloomberg Businessweek reported that Google was making efforts to keep Android more up-to-date, including accelerated rates of security updates, rolling out technological workarounds, reducing requirements for phone testing, and ranking phone makers in an attempt to "shame" them into better behavior. As stated by Bloomberg: "As smartphones get more capable, complex and hackable, having the latest software work closely with the hardware is increasingly important". Hiroshi Lockheimer, the Android lead, admitted that "It's not an ideal situation", further commenting that the lack of updates is "the weakest link on security on Android". Wireless carriers were described in the report as the "most challenging discussions", due to their slow approval time while testing on their networks, despite some carriers, including Verizon Wireless and Sprint Corporation, already shortening their approval times. In a further effort for persuasion, Google shared a list of top phone makers measured by updated devices with its Android partners, and is considering making the list public. Mike Chan, co-founder of phone maker Nextbit and former Android developer, said that "The best way to solve this problem is a massive re-architecture of the operating system", "or Google could invest in training manufacturers and carriers 'to be good Android citizens. In May 2017, with the announcement of Android 8.0, Google introduced Project Treble, a major re-architect of the Android OS framework designed to make it easier, faster, and less costly for manufacturers to update devices to newer versions of Android. Project Treble separates the vendor implementation (device-specific, lower-level software written by silicon manufacturers) from the Android OS framework via a new "vendor interface". In Android 7.0 and earlier, no formal vendor interface exists, so device makers must update large portions of the Android code to move a device to a newer version of the operating system. With Treble, the new stable vendor interface provides access to the hardware-specific parts of Android, enabling device makers to deliver new Android releases simply by updating the Android OS framework, "without any additional work required from the silicon manufacturers." In September 2017, Google's Project Treble team revealed that, as part of their efforts to improve the security lifecycle of Android devices, Google had managed to get the Linux Foundation to agree to extend the support lifecycle of the Linux Long-Term Support (LTS) kernel branch from the 2 years that it has historically lasted to 6 years for future versions of the LTS kernel, starting with Linux kernel 4.4. In May 2019, with the announcement of Android 10, Google introduced Project Mainline to simplify and expedite delivery of updates to the Android ecosystem. Project Mainline enables updates to core OS components through the Google Play Store. As a result, important security and performance improvements that previously needed to be part of full OS updates can be downloaded and installed as easily as an app update. Google reported rolling out new amendments in Android 12 aimed at making the use of third-party application stores easier. This announcement rectified the concerns reported regarding the development of Android apps, including a fight over an alternative in-app payment system and difficulties faced by businesses moving online because of COVID-19. Linux kernel Android's kernel is based on the Linux kernel's long-term support (LTS) branches. , Android uses versions 4.14, 4.19 or 5.4 of the Linux kernel. The actual kernel depends on the individual device. Android's variant of the Linux kernel has further architectural changes that are implemented by Google outside the typical Linux kernel development cycle, such as the inclusion of components like device trees, ashmem, ION, and different out of memory (OOM) handling. Certain features that Google contributed back to the Linux kernel, notably a power management feature called "wakelocks", were initially rejected by mainline kernel developers partly because they felt that Google did not show any intent to maintain its own code. Google announced in April 2010 that they would hire two employees to work with the Linux kernel community, but Greg Kroah-Hartman, the current Linux kernel maintainer for the stable branch, said in December 2010 that he was concerned that Google was no longer trying to get their code changes included in mainstream Linux. Google engineer Patrick Brady once stated in the company's developer conference that "Android is not Linux", with Computerworld adding that "Let me make it simple for you, without Linux, there is no Android". Ars Technica wrote that "Although Android is built on top of the Linux kernel, the platform has very little in common with the conventional desktop Linux stack". In August 2011, Linus Torvalds said that "eventually Android and Linux would come back to a common kernel, but it will probably not be for four to five years". In December 2011, Greg Kroah-Hartman announced the start of Android Mainlining Project, which aims to put some Android drivers, patches and features back into the Linux kernel, starting in Linux 3.3. Linux included the autosleep and wakelocks capabilities in the 3.5 kernel, after many previous attempts at a merger. The interfaces are the same but the upstream Linux implementation allows for two different suspend modes: to memory (the traditional suspend that Android uses), and to disk (hibernate, as it is known on the desktop). Google maintains a public code repository that contains their experimental work to re-base Android off the latest stable Linux versions. Android is a Linux distribution according to the Linux Foundation, Google's open-source chief Chris DiBona, and several journalists. Others, such as Google engineer Patrick Brady, say that Android is not Linux in the traditional Unix-like Linux distribution sense; Android does not include the GNU C Library (it uses Bionic as an alternative C library) and some other components typically found in Linux distributions. With the release of Android Oreo in 2017, Google began to require that devices shipped with new SoCs had Linux kernel version 4.4 or newer, for security reasons. Existing devices upgraded to Oreo, and new products launched with older SoCs, were exempt from this rule. Rooting The flash storage on Android devices is split into several partitions, such as /system/ for the operating system itself, and /data/ for user data and application installations. In contrast to typical desktop Linux distributions, Android device owners are not given root access to the operating system and sensitive partitions such as /system/ are read-only. However, root access can be obtained by exploiting security flaws in Android, which is used frequently by the open-source community to enhance the capabilities and customizability of their devices, but also by malicious parties to install viruses and malware. The process of enabling root access may require the device's bootloader, which is locked by default, to be in an unlocked state. The unlocking process resets the system to factory state, erasing all user data. Software stack On top of the Linux kernel, there are the middleware, libraries and APIs written in C, and application software running on an application framework which includes Java-compatible libraries. Development of the Linux kernel continues independently of Android's other source code projects. Android uses Android Runtime (ART) as its runtime environment (introduced in version 4.4), which uses ahead-of-time (AOT) compilation to entirely compile the application bytecode into machine code upon the installation of an application. In Android 4.4, ART was an experimental feature and not enabled by default; it became the only runtime option in the next major version of Android, 5.0. In versions no longer supported, until version 5.0 when ART took over, Android previously used Dalvik as a process virtual machine with trace-based just-in-time (JIT) compilation to run Dalvik "dex-code" (Dalvik Executable), which is usually translated from the Java bytecode. Following the trace-based JIT principle, in addition to interpreting the majority of application code, Dalvik performs the compilation and native execution of select frequently executed code segments ("traces") each time an application is launched. For its Java library, the Android platform uses a subset of the now discontinued Apache Harmony project. In December 2015, Google announced that the next version of Android would switch to a Java implementation based on the OpenJDK project. Android's standard C library, Bionic, was developed by Google specifically for Android, as a derivation of the BSD's standard C library code. Bionic itself has been designed with several major features specific to the Linux kernel. The main benefits of using Bionic instead of the GNU C Library (glibc) or uClibc are its smaller runtime footprint, and optimization for low-frequency CPUs. At the same time, Bionic is licensed under the terms of the BSD licence, which Google finds more suitable for the Android's overall licensing model. Aiming for a different licensing model, toward the end of 2012, Google switched the Bluetooth stack in Android from the GPL-licensed BlueZ to the Apache-licensed BlueDroid. A new Bluetooth stack, called Gabeldorsche, was developed to try to fix the bugs in the BlueDroid implementation. Android does not have a native X Window System by default, nor does it support the full set of standard GNU libraries. This made it difficult to port existing Linux applications or libraries to Android, until version r5 of the Android Native Development Kit brought support for applications written completely in C or C++. Libraries written in C may also be used in applications by injection of a small shim and usage of the JNI. In current versions of Android, "Toybox", a collection of command-line utilities (mostly for use by apps, as Android does not provide a command-line interface by default), is used (since the release of Marshmallow) replacing a similar "Toolbox" collection found in previous Android versions. Android has another operating system, Trusty OS, within it, as a part of "Trusty" "software components supporting a Trusted Execution Environment (TEE) on mobile devices." "Trusty and the Trusty API are subject to change. [..] Applications for the Trusty OS can be written in C/C++ (C++ support is limited), and they have access to a small C library. [..] All Trusty applications are single-threaded; multithreading in Trusty userspace currently is unsupported. [..] Third-party application development is not supported in" the current version, and software running on the OS and processor for it, run the "DRM framework for protected content. [..] There are many other uses for a TEE such as mobile payments, secure banking, full-disk encryption, multi-factor authentication, device reset protection, replay-protected persistent storage, wireless display ("cast") of protected content, secure PIN and fingerprint processing, and even malware detection." Open-source community Android's source code is released by Google under an open source license, and its open nature has encouraged a large community of developers and enthusiasts to use the open-source code as a foundation for community-driven projects, which deliver updates to older devices, add new features for advanced users or bring Android to devices originally shipped with other operating systems. These community-developed releases often bring new features and updates to devices faster than through the official manufacturer/carrier channels, with a comparable level of quality; provide continued support for older devices that no longer receive official updates; or bring Android to devices that were officially released running other operating systems, such as the HP TouchPad. Community releases often come pre-rooted and contain modifications not provided by the original vendor, such as the ability to overclock or over/undervolt the device's processor. CyanogenMod was the most widely used community firmware, now discontinued and succeeded by LineageOS. There are, as of August 2019, a handful of notable custom Android distributions (ROMs) of the latest Android version 9.0 Pie, which was released publicly in August 2018. See List of custom Android distributions. Historically, device manufacturers and mobile carriers have typically been unsupportive of third-party firmware development. Manufacturers express concern about improper functioning of devices running unofficial software and the support costs resulting from this. Moreover, modified firmware such as CyanogenMod sometimes offer features, such as tethering, for which carriers would otherwise charge a premium. As a result, technical obstacles including locked bootloaders and restricted access to root permissions are common in many devices. However, as community-developed software has grown more popular, and following a statement by the Librarian of Congress in the United States that permits the "jailbreaking" of mobile devices, manufacturers and carriers have softened their position regarding third party development, with some, including HTC, Motorola, Samsung and Sony, providing support and encouraging development. As a result of this, over time the need to circumvent hardware restrictions to install unofficial firmware has lessened as an increasing number of devices are shipped with unlocked or unlockable bootloaders, similar to Nexus series of phones, although usually requiring that users waive their devices' warranties to do so. However, despite manufacturer acceptance, some carriers in the US still require that phones are locked down, frustrating developers and customers. Device codenames Internally, Android identifies each supported device by its device codename, a short string, which may or may not be similar to the model name used in marketing the device. For example, the device codename of the Pixel smartphone is sailfish. The device codename is usually not visible to the end user, but is important for determining compatibility with modified Android versions. It is sometimes also mentioned in articles discussing a device, because it allows to distinguish different hardware variants of a device, even if the manufacturer offers them under the same name. The device codename is available to running applications under android.os.Build.DEVICE. Security and privacy In 2020, Google launched the Android Partner Vulnerability Initiative to improve the security of Android. They also formed an Android security team. Common security threats Research from security company Trend Micro lists premium service abuse as the most common type of Android malware, where text messages are sent from infected phones to premium-rate telephone numbers without the consent or even knowledge of the user. Other malware displays unwanted and intrusive advertisements on the device, or sends personal information to unauthorised third parties. Security threats on Android are reportedly growing exponentially; however, Google engineers have argued that the malware and virus threat on Android is being exaggerated by security companies for commercial reasons, and have accused the security industry of playing on fears to sell virus protection software to users. Google maintains that dangerous malware is actually extremely rare, and a survey conducted by F-Secure showed that only 0.5% of Android malware reported had come from the Google Play store. In 2021, journalists and researchers reported the discovery of spyware, called Pegasus, developed and distributed by a private company which can and has been used to infect both iOS and Android smartphones often – partly via use of 0-day exploits – without the need for any user-interaction or significant clues to the user and then be used to exfiltrate data, track user locations, capture film through its camera, and activate the microphone at any time. Analysis of data traffic by popular smartphones running variants of Android found substantial by-default data collection and sharing with no opt-out by this pre-installed software. Both of these issues are not addressed or cannot be addressed by security patches. Scope of surveillance by public institutions As part of the broader 2013 mass surveillance disclosures it was revealed in September 2013 that the American and British intelligence agencies, the National Security Agency (NSA) and Government Communications Headquarters (GCHQ), respectively, have access to the user data on iPhone, BlackBerry, and Android devices. They are reportedly able to read almost all smartphone information, including SMS, location, emails, and notes. In January 2014, further reports revealed the intelligence agencies' capabilities to intercept the personal information transmitted across the Internet by social networks and other popular applications such as Angry Birds, which collect personal information of their users for advertising and other commercial reasons. GCHQ has, according to The Guardian, a wiki-style guide of different apps and advertising networks, and the different data that can be siphoned from each. Later that week, the Finnish Angry Birds developer Rovio announced that it was reconsidering its relationships with its advertising platforms in the light of these revelations, and called upon the wider industry to do the same. The documents revealed a further effort by the intelligence agencies to intercept Google Maps searches and queries submitted from Android and other smartphones to collect location information in bulk. The NSA and GCHQ insist their activities comply with all relevant domestic and international laws, although the Guardian stated "the latest disclosures could also add to mounting public concern about how the technology sector collects and uses information, especially for those outside the US, who enjoy fewer privacy protections than Americans." Leaked documents published by WikiLeaks, codenamed Vault 7 and dated from 2013 to 2016, detail the capabilities of the Central Intelligence Agency (CIA) to perform electronic surveillance and cyber warfare, including the ability to compromise the operating systems of most smartphones (including Android). Security patches In August 2015, Google announced that devices in the Google Nexus series would begin to receive monthly security patches. Google also wrote that "Nexus devices will continue to receive major updates for at least two years and security patches for the longer of three years from initial availability or 18 months from last sale of the device via the Google Store." The following October, researchers at the University of Cambridge concluded that 87.7% of Android phones in use had known but unpatched security vulnerabilities due to lack of updates and support. Ron Amadeo of Ars Technica wrote also in August 2015 that "Android was originally designed, above all else, to be widely adopted. Google was starting from scratch with zero percent market share, so it was happy to give up control and give everyone a seat at the table in exchange for adoption. [...] Now, though, Android has around 75–80 percent of the worldwide smartphone market—making it not just the world's most popular mobile operating system but arguably the most popular operating system, period. As such, security has become a big issue. Android still uses a software update chain-of-command designed back when the Android ecosystem had zero devices to update, and it just doesn't work". Following news of Google's monthly schedule, some manufacturers, including Samsung and LG, promised to issue monthly security updates, but, as noted by Jerry Hildenbrand in Android Central in February 2016, "instead we got a few updates on specific versions of a small handful of models. And a bunch of broken promises". In a March 2017 post on Google's Security Blog, Android security leads Adrian Ludwig and Mel Miller wrote that "More than 735 million devices from 200+ manufacturers received a platform security update in 2016" and that "Our carrier and hardware partners helped expand deployment of these updates, releasing updates for over half of the top 50 devices worldwide in the last quarter of 2016". They also wrote that "About half of devices in use at the end of 2016 had not received a platform security update in the previous year", stating that their work would continue to focus on streamlining the security updates program for easier deployment by manufacturers. Furthermore, in a comment to TechCrunch, Ludwig stated that the wait time for security updates had been reduced from "six to nine weeks down to just a few days", with 78% of flagship devices in North America being up-to-date on security at the end of 2016. Patches to bugs found in the core operating system often do not reach users of older and lower-priced devices. However, the open-source nature of Android allows security contractors to take existing devices and adapt them for highly secure uses. For example, Samsung has worked with General Dynamics through their Open Kernel Labs acquisition to rebuild Jelly Bean on top of their hardened microvisor for the "Knox" project. Location-tracking Android smartphones have the ability to report the location of Wi-Fi access points, encountered as phone users move around, to build databases containing the physical locations of hundreds of millions of such access points. These databases form electronic maps to locate smartphones, allowing them to run apps like Foursquare, Google Latitude, Facebook Places, and to deliver location-based ads. Third party monitoring software such as TaintDroid, an academic research-funded project, can, in some cases, detect when personal information is being sent from applications to remote servers. Further notable exploits In 2018, Norwegian security firm Promon has unearthed a serious Android security hole which can be exploited to steal login credentials, access messages, and track location, which could be found in all versions of Android, including Android 10. The vulnerability came by exploiting a bug in the multitasking system enabling a malicious app to overlay legitimate apps with fake login screens that users are not aware of when handing in security credentials. Users can also be tricked into granting additional permissions to the malicious apps, which later enable them to perform various nefarious activities, including intercepting texts or calls and stealing banking credentials. Avast Threat Labs also discovered that many pre-installed apps on several hundred new Android devices contain dangerous malware and adware. Some of the preinstalled malware can commit ad fraud or even take over its host device. In 2020, the Which? watchdog reported that more than a billion Android devices released in 2012 or earlier, which was 40% of Android devices worldwide, were at risk of being hacked. This conclusion stemmed from the fact that no security updates were issued for the Android versions below 7.0 in 2019. Which? collaborated with the AV Comparatives anti-virus lab to infect five phone models with malware, and it succeeded in each case. Google refused to comment on the watchdog's speculations. On August 5, 2020, Twitter published a blog urging its users to update their applications to the latest version with regards to a security concern that allowed others to access direct messages. A hacker could easily use the "Android system permissions" to fetch the account credentials in order to do so. The security issue is only with Android 8 (Android Oreo) and Android 9 (Android Pie). Twitter confirmed that updating the app will restrict such practices. Technical security features Android applications run in a sandbox, an isolated area of the system that does not have access to the rest of the system's resources, unless access permissions are explicitly granted by the user when the application is installed, however this may not be possible for pre-installed apps. It is not possible, for example, to turn off the microphone access of the pre-installed camera app without disabling the camera completely. This is valid also in Android versions 7 and 8. Since February 2012, Google has used its Google Bouncer malware scanner to watch over and scan apps available in the Google Play store. A "Verify Apps" feature was introduced in November 2012, as part of the Android 4.2 "Jelly Bean" operating system version, to scan all apps, both from Google Play and from third-party sources, for malicious behaviour. Originally only doing so during installation, Verify Apps received an update in 2014 to "constantly" scan apps, and in 2017 the feature was made visible to users through a menu in Settings. Before installing an application, the Google Play store displays a list of the requirements an app needs to function. After reviewing these permissions, the user can choose to accept or refuse them, installing the application only if they accept. In Android 6.0 "Marshmallow", the permissions system was changed; apps are no longer automatically granted all of their specified permissions at installation time. An opt-in system is used instead, in which users are prompted to grant or deny individual permissions to an app when they are needed for the first time. Applications remember the grants, which can be revoked by the user at any time. Pre-installed apps, however, are not always part of this approach. In some cases it may not be possible to deny certain permissions to pre-installed apps, nor be possible to disable them. The Google Play Services app cannot be uninstalled, nor disabled. Any force stop attempt, result in the app restarting itself. The new permissions model is used only by applications developed for Marshmallow using its software development kit (SDK), and older apps will continue to use the previous all-or-nothing approach. Permissions can still be revoked for those apps, though this might prevent them from working properly, and a warning is displayed to that effect. In September 2014, Jason Nova of Android Authority reported on a study by the German security company Fraunhofer AISEC in antivirus software and malware threats on Android. Nova wrote that "The Android operating system deals with software packages by sandboxing them; this does not allow applications to list the directory contents of other apps to keep the system safe. By not allowing the antivirus to list the directories of other apps after installation, applications that show no inherent suspicious behavior when downloaded are cleared as safe. If then later on parts of the app are activated that turn out to be malicious, the antivirus will have no way to know since it is inside the app and out of the antivirus’ jurisdiction". The study by Fraunhofer AISEC, examining antivirus software from Avast, AVG, Bitdefender, ESET, F-Secure, Kaspersky, Lookout, McAfee (formerly Intel Security), Norton, Sophos, and Trend Micro, revealed that "the tested antivirus apps do not provide protection against customized malware or targeted attacks", and that "the tested antivirus apps were also not able to detect malware which is completely unknown to date but does not make any efforts to hide its malignity". In August 2013, Google announced Android Device Manager (renamed Find My Device in May 2017), a service that allows users to remotely track, locate, and wipe their Android device, with an Android app for the service released in December. In December 2016, Google introduced a Trusted Contacts app, letting users request location-tracking of loved ones during emergencies. In 2020, Trusted Contacts was shut down and the location-sharing feature rolled into Google Maps. On October 8, 2018, Google announced new Google Play store requirements to combat over-sharing of potentially sensitive information, including call and text logs. The issue stems from the fact that many apps request permissions to access users' personal information (even if this information is not needed for the app to function) and some users unquestionably grant these permissions. Alternatively, a permission might be listed in the app manifest as required (as opposed to optional) and the app would not install unless user grants the permission; users can withdraw any, even required, permissions from any app in the device settings after app installation, but few users do this. Google promised to work with developers and create exceptions if their apps require Phone or SMS permissions for "core app functionality". The new policies enforcement started on January 6, 2019, 90 days after policy announcement on October 8, 2018. Furthermore, Google announced a new "target API level requirement" (targetSdkVersion in manifest) at least Android 8.0 (API level 26) for all new apps and app updates. The API level requirement might combat the practice of app developers bypassing some permission screens by specifying early Android versions that had a coarser permission model. Google Play Services and vendor changes Dependence on proprietary Google Play Services and customizations added on top of the operating system by vendors who license Android from Google is causing privacy concerns. Licensing The source code for Android is open-source: it is developed in private by Google, with the source code released publicly when a new version of Android is released. Google publishes most of the code (including network and telephony stacks) under the non-copyleft Apache License version 2.0. which allows modification and redistribution. The license does not grant rights to the "Android" trademark, so device manufacturers and wireless carriers have to license it from Google under individual contracts. Associated Linux kernel changes are released under the copyleft GNU General Public License version 2, developed by the Open Handset Alliance, with the source code publicly available at all times. The only Android release which was not immediately made available as source code was the tablet-only 3.0 Honeycomb release. The reason, according to Andy Rubin in an official Android blog post, was because Honeycomb was rushed for production of the Motorola Xoom, and they did not want third parties creating a "really bad user experience" by attempting to put onto smartphones a version of Android intended for tablets. Only the base Android operating system (including some applications) is open-source software, whereas most Android devices ship with a substantial amount of proprietary software, such as Google Mobile Services, which includes applications such as Google Play Store, Google Search, and Google Play Services a software layer that provides APIs for the integration with Google-provided services, among others. These applications must be licensed from Google by device makers, and can only be shipped on devices which meet its compatibility guidelines and other requirements. Custom, certified distributions of Android produced by manufacturers (such as Samsung Experience) may also replace certain stock Android apps with their own proprietary variants and add additional software not included in the stock Android operating system. With the advent of the Google Pixel line of devices, Google itself has also made specific Android features timed or permanent exclusives to the Pixel series. There may also be "binary blob" drivers required for certain hardware components in the device. The best known fully open source Android services are the LineageOS distribution and MicroG which acts as an open source replacement of Google Play Services. Richard Stallman and the Free Software Foundation have been critical of Android and have recommended the usage of alternatives such as Replicant, because drivers and firmware vital for the proper functioning of Android devices are usually proprietary, and because the Google Play Store application can forcibly install or uninstall applications and, as a result, invite non-free software. In both cases, the use of closed-source software causes the system to become vulnerable to backdoors. It has been argued that because developers are often required to purchase the Google-branded Android license, this has turned the theoretically open system into a freemium service. Leverage over manufacturers Google licenses their Google Mobile Services software, along with the Android trademarks, only to hardware manufacturers for devices that meet Google's compatibility standards specified in the Android Compatibility Program document. Thus, forks of Android that make major changes to the operating system itself do not include any of Google's non-free components, stay incompatible with applications that require them, and must ship with an alternative software marketplace in lieu of Google Play Store. A prominent example of such an Android fork is Amazon's Fire OS, which is used on the Kindle Fire line of tablets, and oriented toward Amazon services. The shipment of Android devices without GMS is also common in mainland China, as Google does not do business there. In 2014, Google also began to require that all Android devices which license the Google Mobile Services software display a prominent "Powered by Android" logo on their boot screens. Google has also enforced preferential bundling and placement of Google Mobile Services on devices, including mandated bundling of the entire main suite of Google applications, mandatory placement of shortcuts to Google Search and the Play Store app on or near the main home screen page in its default configuration, and granting a larger share of search revenue to OEMs who agree to not include third-party app stores on their devices. In March 2018, it was reported that Google had begun to block "uncertified" Android devices from using Google Mobile Services software, and display a warning indicating that "the device manufacturer has preloaded Google apps and services without certification from Google". Users of custom ROMs can register their device ID to their Google account to remove this block. Some stock applications and components in AOSP code that were formerly used by earlier versions of Android, such as Search, Music, Calendar, and the location API, were abandoned by Google in favor of non-free replacements distributed through Play Store (Google Search, Google Play Music, and Google Calendar) and Google Play Services, which are no longer open-source. Moreover, open-source variants of some applications also exclude functions that are present in their non-free versions. These measures are likely intended to discourage forks and encourage commercial licensing in line with Google requirements, as the majority of the operating system's core functionality is dependent on proprietary components licensed exclusively by Google, and it would take significant development resources to develop an alternative suite of software and APIs to replicate or replace them. Apps that do not use Google components would also be at a functional disadvantage, as they can only use APIs contained within the OS itself. In turn, third-party apps may have dependencies on Google Play Services. Members of the Open Handset Alliance, which include the majority of Android OEMs, are also contractually forbidden from producing Android devices based on forks of the OS; in 2012, Acer Inc. was forced by Google to halt production on a device powered by Alibaba Group's Aliyun OS with threats of removal from the OHA, as Google deemed the platform to be an incompatible version of Android. Alibaba Group defended the allegations, arguing that the OS was a distinct platform from Android (primarily using HTML5 apps), but incorporated portions of Android's platform to allow backwards compatibility with third-party Android software. Indeed, the devices did ship with an application store which offered Android apps; however, the majority of them were pirated. Reception Android received a lukewarm reaction when it was unveiled in 2007. Although analysts were impressed with the respected technology companies that had partnered with Google to form the Open Handset Alliance, it was unclear whether mobile phone manufacturers would be willing to replace their existing operating systems with Android. The idea of an open-source, Linux-based development platform sparked interest, but there were additional worries about Android facing strong competition from established players in the smartphone market, such as Nokia and Microsoft, and rival Linux mobile operating systems that were in development. These established players were skeptical: Nokia was quoted as saying "we don't see this as a threat", and a member of Microsoft's Windows Mobile team stated "I don't understand the impact that they are going to have." Since then Android has grown to become the most widely used smartphone operating system and "one of the fastest mobile experiences available". Reviewers have highlighted the open-source nature of the operating system as one of its defining strengths, allowing companies such as Nokia (Nokia X family), Amazon (Kindle Fire), Barnes & Noble (Nook), Ouya, Baidu and others to fork the software and release hardware running their own customised version of Android. As a result, it has been described by technology website Ars Technica as "practically the default operating system for launching new hardware" for companies without their own mobile platforms. This openness and flexibility is also present at the level of the end user: Android allows extensive customisation of devices by their owners and apps are freely available from non-Google app stores and third party websites. These have been cited as among the main advantages of Android phones over others. Despite Android's popularity, including an activation rate three times that of iOS, there have been reports that Google has not been able to leverage their other products and web services successfully to turn Android into the money maker that analysts had expected. The Verge suggested that Google is losing control of Android due to the extensive customization and proliferation of non-Google apps and services Amazon's Kindle Fire line uses Fire OS, a heavily modified fork of Android which does not include or support any of Google's proprietary components, and requires that users obtain software from its competing Amazon Appstore instead of Play Store. In 2014, in an effort to improve prominence of the Android brand, Google began to require that devices featuring its proprietary components display an Android logo on the boot screen. Android has suffered from "fragmentation", a situation where the variety of Android devices, in terms of both hardware variations and differences in the software running on them, makes the task of developing applications that work consistently across the ecosystem harder than rival platforms such as iOS where hardware and software varies less. For example, according to data from OpenSignal in July 2013, there were 11,868 models of Android devices, numerous screen sizes and eight Android OS versions simultaneously in use, while the large majority of iOS users have upgraded to the latest iteration of that OS. Critics such as Apple Insider have asserted that fragmentation via hardware and software pushed Android's growth through large volumes of low end, budget-priced devices running older versions of Android. They maintain this forces Android developers to write for the "lowest common denominator" to reach as many users as possible, who have too little incentive to make use of the latest hardware or software features only available on a smaller percentage of devices. However, OpenSignal, who develops both Android and iOS apps, concluded that although fragmentation can make development trickier, Android's wider global reach also increases the potential reward. Market share Android is the most used operating system on phones in virtually all countries, with some countries, such as India, having over 96% market share. On tablets, usage is more even, as iOS is a bit more popular globally. Research company Canalys estimated in the second quarter of 2009, that Android had a 2.8% share of worldwide smartphone shipments. By May 2010, Android had a 10% worldwide smartphone market share, overtaking Windows Mobile, whilst in the US Android held a 28% share, overtaking iPhone OS. By the fourth quarter of 2010, its worldwide share had grown to 33% of the market becoming the top-selling smartphone platform, overtaking Symbian. In the US it became the top-selling platform in April 2011, overtaking BlackBerry OS with a 31.2% smartphone share, according to comScore. By the third quarter of 2011, Gartner estimated that more than half (52.5%) of the smartphone sales belonged to Android. By the third quarter of 2012 Android had a 75% share of the global smartphone market according to the research firm IDC. In July 2011, Google said that 550,000 Android devices were being activated every day, up from 400,000 per day in May, and more than 100 million devices had been activated with 4.4% growth per week. In September 2012, 500 million devices had been activated with 1.3 million activations per day. In May 2013, at Google I/O, Sundar Pichai announced that 900 million Android devices had been activated. Android market share varies by location. In July 2012, "mobile subscribers aged 13+" in the United States using Android were up to 52%, and rose to 90% in China. During the third quarter of 2012, Android's worldwide smartphone shipment market share was 75%, with 750 million devices activated in total. In April 2013, Android had 1.5 million activations per day. 48 billion application ("app") installation have been performed from the Google Play store, and by September 2013, one billion Android devices had been activated. the Google Play store had over 3 million Android applications published, and apps had been downloaded more than 65 billion times. The operating system's success has made it a target for patent litigation as part of the so-called "smartphone wars" between technology companies. Android devices account for more than half of smartphone sales in most markets, including the US, while "only in Japan was Apple on top" (September–November 2013 numbers). At the end of 2013, over 1.5 billion Android smartphones had been sold in the four years since 2010, making Android the most sold phone and tablet OS. Three billion Android smartphones were estimated to be sold by the end of 2014 (including previous years). According to Gartner research company, Android-based devices outsold all contenders, every year since 2012. In 2013, it outsold Windows 2.8:1 or by 573 million. Android has the largest installed base of all operating systems; Since 2013, devices running it also sell more than Windows, iOS and Mac OS X devices combined. According to StatCounter, which tracks only the use for browsing the web, Android is the most popular mobile operating system since August 2013. Android is the most popular operating system for web browsing in India and several other countries (e.g. virtually all of Asia, with Japan and North Korea exceptions). According to StatCounter, Android is most used on mobile in all African countries, and it stated "mobile usage has already overtaken desktop in several countries including India, South Africa and Saudi Arabia", with virtually all countries in Africa having done so already (except for seven countries, including Egypt), such as Ethiopia and Kenya in which mobile (including tablets) usage is at 90.46% (Android only, accounts for 75.81% of all use there). While Android phones in the Western world almost always include Google's proprietary code (such as Google Play) in the otherwise open-source operating system, Google's proprietary code and trademark is increasingly not used in emerging markets; "The growth of AOSP Android devices goes way beyond just China [..] ABI Research claims that 65 million devices shipped globally with open-source Android in the second quarter of [2014], up from 54 million in the first quarter"; depending on country, percent of phones estimated to be based only on AOSP source code, forgoing the Android trademark: Thailand (44%), Philippines (38%), Indonesia (31%), India (21%), Malaysia (24%), Mexico (18%), Brazil (9%). According to a January 2015 Gartner report, "Android surpassed a billion shipments of devices in 2014, and will continue to grow at a double-digit pace in 2015, with a 26 percent increase year over year." This made it the first time that any general-purpose operating system has reached more than one billion end users within a year: by reaching close to 1.16 billion end users in 2014, Android shipped over four times more than iOS and OS X combined, and over three times more than Microsoft Windows. Gartner expected the whole mobile phone market to "reach two billion units in 2016", including Android. Describing the statistics, Farhad Manjoo wrote in The New York Times that "About one of every two computers sold today is running Android. [It] has become Earth's dominant computing platform." According to a Statistica's estimate, Android smartphones had an installed base of 1.8 billion units in 2015, which was 76% of the estimated total number of smartphones worldwide. Android has the largest installed base of any mobile operating system and, since 2013, the highest-selling operating system overall with sales in 2012, 2013 and 2014 close to the installed base of all PCs. In the second quarter of 2014, Android's share of the global smartphone shipment market was 84.7%, a new record. This had grown to 87.5% worldwide market share by the third quarter of 2016, leaving main competitor iOS with 12.1% market share. According to an April 2017 StatCounter report, Android overtook Microsoft Windows to become the most popular operating system for total Internet usage. It has maintained the plurality since then. In September 2015, Google announced that Android had 1.4 billion monthly active users. This changed to 2 billion monthly active users in May 2017. Adoption on tablets Despite its success on smartphones, initially Android tablet adoption was slow, then later caught up with the iPad, in most countries. One of the main causes was the chicken or the egg situation where consumers were hesitant to buy an Android tablet due to a lack of high quality tablet applications, but developers were hesitant to spend time and resources developing tablet applications until there was a significant market for them. The content and app "ecosystem" proved more important than hardware specs as the selling point for tablets. Due to the lack of Android tablet-specific applications in 2011, early Android tablets had to make do with existing smartphone applications that were ill-suited to larger screen sizes, whereas the dominance of Apple's iPad was reinforced by the large number of tablet-specific iOS applications. Despite app support in its infancy, a considerable number of Android tablets, like the Barnes & Noble Nook (alongside those using other operating systems, such as the HP TouchPad and BlackBerry PlayBook) were rushed out to market in an attempt to capitalize on the success of the iPad. InfoWorld has suggested that some Android manufacturers initially treated their first tablets as a "Frankenphone business", a short-term low-investment opportunity by placing a smartphone-optimized Android OS (before Android 3.0 Honeycomb for tablets was available) on a device while neglecting user interface. This approach, such as with the Dell Streak, failed to gain market traction with consumers as well as damaging the early reputation of Android tablets. Furthermore, several Android tablets such as the Motorola Xoom were priced the same or higher than the iPad, which hurt sales. An exception was the Amazon Kindle Fire, which relied upon lower pricing as well as access to Amazon's ecosystem of applications and content. This began to change in 2012, with the release of the affordable Nexus 7 and a push by Google for developers to write better tablet applications. According to International Data Corporation, shipments of Android-powered tablets surpassed iPads in Q3 2012. As of the end of 2013, over 191.6 million Android tablets had sold in three years since 2011. This made Android tablets the most-sold type of tablet in 2013, surpassing iPads in the second quarter of 2013. According to StatCounter's web use statistics, , Android tablets represent the majority of tablet devices used in Africa (70%), South America (65%), while less than half elsewhere, e.g. Europe (44%), Asia (44%), North America (34%) and Oceania/Australia (18%). There are countries on all continents where Android tablets are the majority, for example, Mexico. In March 2016, Galen Gruman of InfoWorld stated that Android devices could be a "real part of your business [..] there's no longer a reason to keep Android at arm's length. It can now be as integral to your mobile portfolio as Apple's iOS devices are". A year earlier, Gruman had stated that Microsoft's own mobile Office apps were "better on iOS and Android" than on Microsoft's own Windows 10 devices. Platform information , just before the release of Android 12, Android 11, the then-most-recent Android version, is the most popular Android version, on both smartphones and tablets. Android 11 is most popular on smartphones at 31.8%, with Android 10 usage at 30.0%, giving Android 11 and 10 together over 60% the share. Usage of Pie 9.0 and newer, i.e. supported versions, is at 77% (with Oreo 8.1 at 83%), the rest of users are not supported with security updates. Android 11 is most used in many countries, ranging from the United States to India, and in virtually all other countries (e.g. in China) is Android 10 the most popular version. On tablets, the latest version Android 11 is most popular at 21% overtaking Android 9.0 Pie in July 2021, which is now second at 15% (topped out at over 20%). Usage of Pie 9.0 and newer, i.e. supported versions, is at 45% on Android tablets, and with Oreo 8.1, until recently supported, at 51.1%. The usage share varies a lot by country: e.g. Android 9.0 Pie is the single version with the greatest usage share in the United States (and the UK) at 31.64%, while the latest version Android 11 is most widespread in e.g. India, Canada, Australia, and most European countries, and others all over the world; Oreo 8.1 most used in China. , 66% of devices have Vulkan support (47% on newer Vulkan 1.1), the successor to OpenGL. At the same time 91.5% of the devices have support for or higher (in addition, the rest of devices, 8.50%, use version 2.0), with 73.50% using the latest version . Application piracy In general, paid Android applications can easily be pirated. In a May 2012 interview with Eurogamer, the developers of Football Manager stated that the ratio of pirated players vs legitimate players was 9:1 for their game Football Manager Handheld. However, not every developer agreed that piracy rates were an issue; for example, in July 2012 the developers of the game Wind-up Knight said that piracy levels of their game were only 12%, and most of the piracy came from China, where people cannot purchase apps from Google Play. In 2010, Google released a tool for validating authorized purchases for use within apps, but developers complained that this was insufficient and trivial to crack. Google responded that the tool, especially its initial release, was intended as a sample framework for developers to modify and build upon depending on their needs, not as a finished piracy solution. Android "Jelly Bean" introduced the ability for paid applications to be encrypted, so that they may work only on the device for which they were purchased. Legal issues The success of Android has made it a target for patent and copyright litigation between technology companies, both Android and Android phone manufacturers having been involved in numerous patent lawsuits and other legal challenges. Patent lawsuit with Oracle On August 12, 2010, Oracle sued Google over claimed infringement of copyrights and patents related to the Java programming language. Oracle originally sought damages up to $6.1 billion, but this valuation was rejected by a United States federal judge who asked Oracle to revise the estimate. In response, Google submitted multiple lines of defense, counterclaiming that Android did not infringe on Oracle's patents or copyright, that Oracle's patents were invalid, and several other defenses. They said that Android's Java runtime environment is based on Apache Harmony, a clean room implementation of the Java class libraries, and an independently developed virtual machine called Dalvik. In May 2012, the jury in this case found that Google did not infringe on Oracle's patents, and the trial judge ruled that the structure of the Java APIs used by Google was not copyrightable. The parties agreed to zero dollars in statutory damages for a small amount of copied code. On May 9, 2014, the Federal Circuit partially reversed the district court ruling, ruling in Oracle's favor on the copyrightability issue, and remanding the issue of fair use to the district court. In December 2015, Google announced that the next major release of Android (Android Nougat) would switch to OpenJDK, which is the official open-source implementation of the Java platform, instead of using the now-discontinued Apache Harmony project as its runtime. Code reflecting this change was also posted to the AOSP source repository. In its announcement, Google claimed this was part of an effort to create a "common code base" between Java on Android and other platforms. Google later admitted in a court filing that this was part of an effort to address the disputes with Oracle, as its use of OpenJDK code is governed under the GNU General Public License (GPL) with a linking exception, and that "any damages claim associated with the new versions expressly licensed by Oracle under OpenJDK would require a separate analysis of damages from earlier releases". In June 2016, a United States federal court ruled in favor of Google, stating that its use of the APIs was fair use. In April 2021, the United Supreme Court ruled that Google's use of the Java APIs was within the bounds of fair use, reversing the Federal Circuit Appeals Court ruling and remanding the case for further hearing. The majority opinion began with the assumption that the APIs may be copyrightable, and thus proceeded with a review of the factors that contributed to fair use. Anti-competitive challenges in Europe In 2013, FairSearch, a lobbying organization supported by Microsoft, Oracle and others, filed a complaint regarding Android with the European Commission, alleging that its free-of-charge distribution model constituted anti-competitive predatory pricing. The Free Software Foundation Europe, whose donors include Google, disputed the Fairsearch allegations. On April 20, 2016, the EU filed a formal antitrust complaint against Google based upon the FairSearch allegations, arguing that its leverage over Android vendors, including the mandatory bundling of the entire suite of proprietary Google software, hindering the ability for competing search providers to be integrated into Android, and barring vendors from producing devices running forks of Android, constituted anti-competitive practices. In August 2016, Google was fined US$6.75 million by the Russian Federal Antimonopoly Service (FAS) under similar allegations by Yandex. The European Commission issued its decision on July 18, 2018, determining that Google had conducted three operations related to Android that were in violation of antitrust regulations: bundling Google's search and Chrome as part of Android, blocking phone manufacturers from using forked versions of Android, and establishing deals with phone manufacturers and network providers to exclusively bundle the Google search application on handsets (a practice Google ended by 2014). The EU fined Google for (about ) and required the company to end this conduct within 90 days. Google filed its appeal of the ruling in October 2018, though will not ask for any interim measures to delay the onset of conduct requirements. On October 16, 2018, Google announced that it would change its distribution model for Google Mobile Services in the EU, since part of its revenues streams for Android which came through use of Google Search and Chrome were now prohibited by the EU's ruling. While the core Android system remains free, OEMs in Europe would be required to purchase a paid license to the core suite of Google applications, such as Gmail, Google Maps and the Google Play Store. Google Search will be licensed separately, with an option to include Google Chrome at no additional cost atop Search. European OEMs can bundle third-party alternatives on phones and devices sold to customers, if they so choose. OEMs will no longer be barred from selling any device running incompatible versions of Android in Europe. Others In addition to lawsuits against Google directly, various proxy wars have been waged against Android indirectly by targeting manufacturers of Android devices, with the effect of discouraging manufacturers from adopting the platform by increasing the costs of bringing an Android device to market. Both Apple and Microsoft have sued several manufacturers for patent infringement, with Apple's ongoing legal action against Samsung being a particularly high-profile case. In January 2012, Microsoft said they had signed patent license agreements with eleven Android device manufacturers, whose products account for "70 percent of all Android smartphones" sold in the US and 55% of the worldwide revenue for Android devices. These include Samsung and HTC. Samsung's patent settlement with Microsoft included an agreement to allocate more resources to developing and marketing phones running Microsoft's Windows Phone operating system. Microsoft has also tied its own Android software to patent licenses, requiring the bundling of Microsoft Office Mobile and Skype applications on Android devices to subsidize the licensing fees, while at the same time helping to promote its software lines. Google has publicly expressed its frustration for the current patent landscape in the United States, accusing Apple, Oracle and Microsoft of trying to take down Android through patent litigation, rather than innovating and competing with better products and services. In August 2011, Google purchased Motorola Mobility for US$12.5 billion, which was viewed in part as a defensive measure to protect Android, since Motorola Mobility held more than 17,000 patents. In December 2011, Google bought over a thousand patents from IBM. Turkey's competition authority investigations about default search engine in Android, started in 2017, led to a US$17.4 million fine in September 2018 and a fine of 0.05 percent of Google's revenue per day in November 2019 when Google didn't meet the requirements. In December 2019, Google stopped issuing licenses for new Android phone models sold in Turkey. Other uses Google has developed several variations of Android for specific use cases, including Android Wear, later renamed Wear OS, for wearable devices such as wrist watches, Android TV for televisions, Android Things for smart or Internet of things devices and Android Automotive for cars. Additionally, by providing infrastructure that combines dedicated hardware and dedicated applications running on regular Android, Google have opened up the platform for its use in particular usage scenarios, such as the Android Auto app for cars, and Daydream, a Virtual Reality platform. The open and customizable nature of Android allows device makers to use it on other electronics as well, including laptops, netbooks, and desktop computers, cameras, headphones, home automation systems, game consoles, media players, satellites, routers, printers, payment terminals, automated teller machines, and robots. Additionally, Android has been installed and run on a variety of less-technical objects, including calculators, single-board computers, feature phones, electronic dictionaries, alarm clocks, refrigerators, landline telephones, coffee machines, bicycles, and mirrors. Ouya, a video game console running Android, became one of the most successful Kickstarter campaigns, crowdfunding US$8.5m for its development, and was later followed by other Android-based consoles, such as Nvidia's Shield Portable an Android device in a video game controller form factor. In 2011, Google demonstrated "Android@Home", a home automation technology which uses Android to control a range of household devices including light switches, power sockets and thermostats. Prototype light bulbs were announced that could be controlled from an Android phone or tablet, but Android head Andy Rubin was cautious to note that "turning a lightbulb on and off is nothing new", pointing to numerous failed home automation services. Google, he said, was thinking more ambitiously and the intention was to use their position as a cloud services provider to bring Google products into customers' homes. Parrot unveiled an Android-based car stereo system known as Asteroid in 2011, followed by a successor, the touchscreen-based Asteroid Smart, in 2012. In 2013, Clarion released its own Android-based car stereo, the AX1. In January 2014, at the Consumer Electronics Show (CES), Google announced the formation of the Open Automotive Alliance, a group including several major automobile makers (Audi, General Motors, Hyundai, and Honda) and Nvidia, which aims to produce Android-based in-car entertainment systems for automobiles, "[bringing] the best of Android into the automobile in a safe and seamless way." Android comes preinstalled on a few laptops (a similar functionality of running Android applications is also available in Google's Chrome OS) and can also be installed on personal computers by end users. On those platforms Android provides additional functionality for physical keyboards and mice, together with the "Alt-Tab" key combination for switching applications quickly with a keyboard. In December 2014, one reviewer commented that Android's notification system is "vastly more complete and robust than in most environments" and that Android is "absolutely usable" as one's primary desktop operating system. In October 2015, The Wall Street Journal reported that Android will serve as Google's future main laptop operating system, with the plan to fold Chrome OS into it by 2017. Google's Sundar Pichai, who led the development of Android, explained that "mobile as a computing paradigm is eventually going to blend with what we think of as desktop today." Also, back in 2009, Google co-founder Sergey Brin himself said that Chrome OS and Android would "likely converge over time." Lockheimer, who replaced Pichai as head of Android and Chrome OS, responded to this claim with an official Google blog post stating that "While we've been working on ways to bring together the best of both operating systems, there's no plan to phase out Chrome OS [which has] guaranteed auto-updates for five years". That is unlike Android where support is shorter with "EOL dates [being..] at least 3 years [into the future] for Android tablets for education". At Google I/O in May 2016, Google announced Daydream, a virtual reality platform that relies on a smartphone and provides VR capabilities through a virtual reality headset and controller designed by Google itself. The platform is built into Android starting with Android Nougat, differentiating from standalone support for VR capabilities. The software is available for developers, and was released in 2016. Mascot The mascot of Android is a green android robot, as related to the software's name. Although it has no official name, the Android team at Google reportedly call it "Bugdroid". It was designed by then-Google graphic designer Irina Blok on November 5, 2007 when Android was announced. Contrary to reports that she was tasked with a project to create an icon, Blok confirmed in an interview that she independently developed it and made it open source. The robot design was initially not presented to Google, but it quickly became commonplace in the Android development team, with various variations of it created by the developers there who liked the figure, as it was free under a Creative Commons license. Its popularity amongst the development team eventually led to Google adopting it as an official icon as part of the Android logo when it launched to consumers in 2008. See also Comparison of mobile operating systems Index of Android OS articles List of Android smartphones References Explanatory notes Citations External links Android Developers Android Open Source Project 2008 software Alphabet Inc. ARM operating systems Cloud clients Computer-related introductions in 2008 Computing platforms Embedded Linux distributions Free mobile software Google acquisitions Google software Linux distributions without systemd Mobile Linux Operating system families Smartphones Software using the Apache license Tablet operating systems Linux distributions

Operating System (OS)

Comparison of user features of operating systems Comparison of user features of operating systems refers to a comparison of the general user features of major operating systems in a narrative format. It does not encompass a full exhaustive comparison or description of all technical details of all operating systems. It is a comparison of basic roles and the most prominent features. It also includes the most important features of the operating system's origins, historical development, and role. Overview An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may also include accounting software for cost allocation of processor time, mass storage, printing, and other resources. For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between programs and the computer hardware, although the application code is usually executed directly by the hardware and frequently makes system calls to an OS function or is interrupted by it. Operating systems are found on many devices that contain a computer from cellular phones and video game consoles to web servers and supercomputers. The dominant general-purpose desktop operating system is Microsoft Windows with a market share of around 76.45%. macOS by Apple Inc. is in second place (17.72%), and the varieties of Linux are collectively in third place (1.73%). In the mobile sector (including smartphones and tablets), Android's share is up to 72% in the year 2020. According to third quarter 2016 data, Android's share on smartphones is dominant with 87.5 percent with also a growth rate of 10.3 percent per year, followed by Apple's iOS with 12.1 percent with per year decrease in market share of 5.2 percent, while other operating systems amount to just 0.3 percent. Linux distributions are dominant in the server and supercomputing sectors. Other specialized classes of operating systems (special-purpose operating systems)), such as embedded and real-time systems, exist for many applications. Security-focused operating systems also exist. Some operating systems have low system requirements (i.e. light-weight Linux distribution). Others may have higher system requirements. Some operating systems require installation or may come pre-installed with purchased computers (OEM-installation), whereas others may run directly from media (i.e. live cd) or flash memory (i.e. usb stick). MS-DOS Overview MS-DOS (acronym for Microsoft Disk Operating System) is an operating system for x86-based personal computers mostly developed by Microsoft. Collectively, MS-DOS, its rebranding as IBM PC DOS, and some operating systems attempting to be compatible with MS-DOS, are sometimes referred to as "DOS" (which is also the generic acronym for disk operating system). MS-DOS was the main operating system for IBM PC compatible personal computers during the 1980s, from which point it was gradually superseded by operating systems offering a graphical user interface (GUI), in various generations of the graphical Microsoft Windows operating system. IBM licensed and re-released it in 1981 as PC DOS 1.0 for use in its PCs. Although MS-DOS and PC DOS were initially developed in parallel by Microsoft and IBM, the two products diverged after twelve years, in 1993, with recognizable differences in compatibility, syntax, and capabilities. During its lifetime, several competing products were released for the x86 platform, and MS-DOS went through eight versions, until development ceased in 2000. Initially, MS-DOS was targeted at Intel 8086 processors running on computer hardware using floppy disks to store and access not only the operating system, but application software and user data as well. Progressive version releases delivered support for other mass storage media in ever greater sizes and formats, along with added feature support for newer processors and rapidly evolving computer architectures. Ultimately, it was the key product in Microsoft's development from a programming language company to a diverse software development firm, providing the company with essential revenue and marketing resources. It was also the underlying basic operating system on which early versions of Windows ran as a GUI. Microsoft Windows Overview Microsoft Windows, commonly referred to as Windows, is a group of several proprietary graphical operating system families, all of which are developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. Active Microsoft Windows families include Windows NT and Windows IoT; these may encompass subfamilies, (e.g. Windows Server or Windows Embedded Compact) (Windows CE). Defunct Microsoft Windows families include Windows 9x, Windows Mobile, and Windows Phone. Microsoft introduced an operating environment named Windows on 20 November 1985, as a graphical operating system shell for MS-DOS in response to the growing interest in graphical user interfaces (GUIs). Microsoft Windows came to dominate the world's personal computer (PC) market with over 90% market share, overtaking Mac OS, which had been introduced in 1984, while Microsoft has in 2020 lost its dominance of the consumer operating system market, with Windows down to 30%, lower than Apple's 31% mobile-only share (65% for desktop operating systems only, i.e. "PCs" vs. Apple's 28% desktop share) in its home market, the US, and 32% globally (77% for desktops), where Google's Android leads. Apple came to see Windows as an unfair encroachment on their innovation in GUI development as implemented on products such as the Lisa and Macintosh (eventually settled in court in Microsoft's favor in 1993). On PCs, Windows is still the most popular operating system in all countries. However, in 2014, Microsoft admitted losing the majority of the overall operating system market to Android, because of the massive growth in sales of Android smartphones. In 2014, the number of Windows devices sold was less than 25% that of Android devices sold. This comparison, however, may not be fully relevant, as the two operating systems traditionally target different platforms. Still, numbers for server use of Windows (that are comparable to competitors) show one third market share, similar to that for end user use. , the most recent version of Windows for PCs, tablets and embedded devices is Windows 10, version 20H2. The most recent version for server computers is Windows Server, version 20H2. A specialized version of Windows also runs on the Xbox One video game console. Windows 95 Windows 95 introduced a redesigned shell based around a desktop metaphor; File shortcuts (also known as shell links) were introduced and the desktop was re-purposed to hold shortcuts to applications, files and folders, reminiscent of Mac OS. In Windows 3.1 the desktop was used to display icons of running applications. In Windows 95, the currently running applications were displayed as buttons on a taskbar across the bottom of the screen. The taskbar also contained a notification area used to display icons for background applications, a volume control and the current time. The Start menu, invoked by clicking the "Start" button on the taskbar or by pressing the Windows key, was introduced as an additional means of launching applications or opening documents. While maintaining the program groups used by its predecessor Program Manager, it also displayed applications within cascading sub-menus. The previous File Manager program was replaced by Windows Explorer and the Explorer-based Control Panel and several other special folders were added such as My Computer, Dial Up Networking, Recycle Bin, Network Neighborhood, My Documents, Recent documents, Fonts, Printers, and My Briefcase among others. AutoRun was introduced for CD drives. The user interface looked dramatically different from prior versions of Windows, but its design language did not have a special name like Metro, Aqua or Material Design. Internally it was called "the new shell" and later simply "the shell". The subproject within Microsoft to develop the new shell was internally known as "Stimpy". In 1994, Microsoft designers Mark Malamud and Erik Gavriluk approached Brian Eno to compose music for the Windows 95 project. The result was the six-second start-up music-sound of the Windows 95 operating system, The Microsoft Sound and it was first released as a startup sound in May 1995 on Windows 95 May Test Release build 468. When released for Windows 95 and Windows NT 4.0, Internet Explorer 4 came with an optional Windows Desktop Update, which modified the shell to provide several additional updates to Windows Explorer, including a Quick Launch toolbar, and new features integrated with Internet Explorer, such as Active Desktop (which allowed Internet content to be displayed directly on the desktop). Some of the user interface elements introduced in Windows 95, such as the desktop, taskbar, Start menu and Windows Explorer file manager, remained fundamentally unchanged on future versions of Windows. Windows 10 A new iteration of the Start menu is used on the Windows 10 desktop, with a list of places and other options on the left side, and tiles representing applications on the right. The menu can be resized, and expanded into a full-screen display, which is the default option in Tablet mode. A new virtual desktop system was added. A feature known as Task View displays all open windows and allows users to switch between them, or switch between multiple workspaces. Universal apps, which previously could be used only in full screen mode, can now be used in self-contained windows similarly to other programs. Program windows can now be snapped to quadrants of the screen by dragging them to the corner. When a window is snapped to one side of the screen, Task View appears and the user is prompted to choose a second window to fill the unused side of the screen (called "Snap Assist"). Windows' system icons were also changed. Charms have been removed; their functionality in universal apps is accessed from an App commands menu on their title bar. In its place is Action Center, which displays notifications and settings toggles. It is accessed by clicking an icon in the notification area, or dragging from the right of the screen. Notifications can be synced between multiple devices. The Settings app (formerly PC Settings) was refreshed and now includes more options that were previously exclusive to the desktop Control Panel. Windows 10 is designed to adapt its user interface based on the type of device being used and available input methods. It offers two separate user interface modes: a user interface optimized for mouse and keyboard, and a "Tablet mode" designed for touchscreens. Users can toggle between these two modes at any time, and Windows can prompt or automatically switch when certain events occur, such as disabling Tablet mode on a tablet if a keyboard or mouse is plugged in, or when a 2-in-1 PC is switched to its laptop state. In Tablet mode, programs default to a maximized view, and the taskbar contains a back button and hides buttons for opened or pinned programs by default; Task View is used instead to switch between programs. The full screen Start menu is used in this mode, similarly to Windows 8, but scrolls vertically instead of horizontally. Apple Macintosh Apple Classic MacOS Overview The classic Mac OS (System Software) is the series of operating systems developed for the Macintosh family of personal computers by Apple Inc. from 1984 to 2001, starting with System 1 and ending with Mac OS 9. The Macintosh operating system is credited with having popularized the graphical user interface concept. It was included with every Macintosh that was sold during the era in which it was developed, and many updates to the system software were done in conjunction with the introduction of new Macintosh systems. Apple released the original Macintosh on 24 January 1984. The first version of the system software, which had no official name, was partially based on the Lisa OS, which Apple previously released for the Lisa computer in 1983. As part of an agreement allowing Xerox to buy shares in Apple at a favorable price, it also used concepts from the Xerox PARC Alto computer, which former Apple CEO Steve Jobs and other Lisa team members had previewed. This operating system consisted of the Macintosh Toolbox ROM and the "System Folder", a set of files that were loaded from disk. The name Macintosh System Software came into use in 1987 with System 5. Apple rebranded the system as Mac OS in 1996, starting officially with version 7.6, due in part to its Macintosh clone program. That program ended after the release of Mac OS 8 in 1997. The last major release of the system was Mac OS 9 in 1999. Initial versions of the System Software ran one application at a time. With the Macintosh 512K, a system extension called the Switcher was developed to use this additional memory to allow multiple programs to remain loaded. The software of each loaded program used the memory exclusively; only when activated by the Switcher did the program appear, even the Finder's desktop. With the Switcher, the now familiar Clipboard feature allowed cut and paste between the loaded programs across switches including the desktop. With the introduction of System 5, a cooperative multitasking extension called MultiFinder was added, which allowed content in windows of each program to remain in a layered view over the desktop, and was later integrated into System 7 as part of the operating system along with support for virtual memory. By the mid-1990s, however, contemporary operating systems such as Windows NT, OS/2, and NeXTSTEP had all brought pre-emptive multitasking, protected memory, access controls, and multi-user capabilities to desktop computers, The Macintosh's limited memory management and susceptibility to conflicts among extensions that provide additional functionality, such as networking or support for a particular device, led to significant criticism of the operating system, and was a factor in Apple's declining market share at the time. After two aborted attempts at creating a successor to the Macintosh System Software called Taligent and Copland, and a four-year development effort spearheaded by Steve Jobs' return to Apple in 1997, Apple replaced Mac OS with a new operating system in 2001 named Mac OS X; the X signifying the underlying Unix system family base shared with Jobs' development of the NeXTSTEP operating systems on the NeXT computer. It retained most of the user interface design elements of the classic Mac OS, and there was some overlap of application frameworks for compatibility, but the two operating systems otherwise have completely different origins and architectures. The final updates to Mac OS 9 released in 2001 provided interoperability with Mac OS X. The name "Classic" that now signifies the historical Mac OS as a whole is a reference to the Classic Environment, a compatibility layer that helped ease the transition to Mac OS X (now macOS). Apple MacOS X Overview MacOS previously Mac OS X and later OS X) is a series of proprietary graphical operating systems developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop, laptop and home computers, and by web usage, it is the second most widely used desktop OS, after Microsoft Windows. macOS is the direct successor to the classic Mac OS, the line of Macintosh operating systems with nine releases from 1984 to 1999. macOS adopted the Unix kernel and inherited technologies developed between 1985 and 1997 at NeXT, the company that Apple co-founder Steve Jobs created after leaving Apple in 1985. Releases from Mac OS X 10.5 Leopard and thereafter are UNIX 03 certified. Apple's mobile operating system, iOS, has been considered a variant of macOS. Mac OS X 10.0 (code named Cheetah) was the first major release and version of macOS, Apple's desktop and server operating system. Mac OS X 10.0 was released on 24 March 2001 for a price of US$129. It was the successor of the Mac OS X Public Beta and the predecessor of Mac OS X 10.1 (code named Puma). Mac OS X 10.0 was a radical departure from the classic Mac OS and was Apple's long-awaited answer for a next generation Macintosh operating system. It introduced a brand new code base completely separate from Mac OS 9's as well as all previous Apple operating systems, and had a new Unix-like core, Darwin, which features a new memory management system. Unlike releases of Mac OS X 10.2 to 10.8, the operating system was not externally marketed with the name of a big cat. Apple MacOS Components The Finder is a file browser allowing quick access to all areas of the computer, which has been modified throughout subsequent releases of macOS. Quick Look has been part of the Finder since version 10.5. It allows for dynamic previews of files, including videos and multi-page documents without opening any other applications. Spotlight, a file searching technology which has been integrated into the Finder since version 10.4, allows rapid real-time searches of data files; mail messages; photos; and other information based on item properties (metadata) and/or content. macOS makes use of a Dock, which holds file and folder shortcuts as well as minimized windows. Apple added Exposé in version 10.3 (called Mission Control since version 10.7), a feature which includes three functions to help accessibility between windows and desktop. Its functions are to instantly display all open windows as thumbnails for easy navigation to different tasks, display all open windows as thumbnails from the current application, and hide all windows to access the desktop. FileVault is optional encryption of the user's files with the 128-bit Advanced Encryption Standard (AES-128). Features introduced in version 10.4 include Automator, an application designed to create an automatic workflow for different tasks; Dashboard, a full-screen group of small applications called desktop widgets that can be called up and dismissed in one keystroke; and Front Row, a media viewer interface accessed by the Apple Remote. Sync Services allows applications to access a centralized extensible database for various elements of user data, including calendar and contact items. The operating system then managed conflicting edits and data consistency. All system icons are scalable up to 512×512 pixels as of version 10.5 to accommodate various places where they appear in larger size, including for example the Cover Flow view, a three-dimensional graphical user interface included with iTunes, the Finder, and other Apple products for visually skimming through files and digital media libraries via cover artwork. That version also introduced Spaces, a virtual desktop implementation which enables the user to have more than one desktop and display them in an Exposé-like interface; an automatic backup technology called Time Machine, which allows users to view and restore previous versions of files and application data; and Screen Sharing was built in for the first time. In more recent releases, Apple has developed support for emoji characters by including the proprietary Apple Color Emoji font. Apple has also connected macOS with social networks such as Twitter and Facebook through the addition of share buttons for content such as pictures and text. Apple has brought several applications and features that originally debuted in iOS, its mobile operating system, to macOS in recent releases, notably the intelligent personal assistant Siri, which was introduced in version 10.12 of macOS. Unix and Unix-like systems Unix Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in the 1970s at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and others. Initially intended for use inside the Bell System, AT&T licensed Unix to outside parties in the late 1970s, leading to a variety of both academic and commercial Unix variants from vendors including University of California, Berkeley (BSD), Microsoft (Xenix), Sun Microsystems (SunOS/Solaris), HP/HPE (HP-UX), and IBM (AIX). In the early 1990s, AT&T sold its rights in Unix to Novell, which then sold its Unix business to the Santa Cruz Operation (SCO) in 1995. The UNIX trademark passed to The Open Group, an industry consortium founded in 1996, which allows the use of the mark for certified operating systems that comply with the Single UNIX Specification (SUS). However, Novell continues to own the Unix copyrights, which the SCO Group, Inc. v. Novell, Inc. court case (2010) confirmed. Unix systems are characterized by a modular design that is sometimes called the "Unix philosophy". According to this philosophy, the operating system should provide a set of simple tools, each of which performs a limited, well-defined function. A unified filesystem (the Unix filesystem) and an inter-process communication mechanism known as "pipes" serve as the main means of communication, and a shell scripting and command language (the Unix shell) is used to combine the tools to perform complex workflows. Unix distinguishes itself from its predecessors as the first portable operating system: almost the entire operating system is written in the C programming language, which allows Unix to operate on numerous platforms. macOS, described above, is a Unix-like system, and, beginning with Mac OS X Leopard, is certified to comply with the SUS. Linux Linux is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on 17 September 1991, by Linus Torvalds. Linux is typically packaged in a Linux distribution. Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name "GNU/Linux" to emphasize the importance of GNU software, causing some controversy. Popular Linux distributions include Debian, Fedora, and Ubuntu. Commercial distributions include Red Hat Enterprise Linux and SUSE Linux Enterprise Server. Desktop Linux distributions include a windowing system such as X11 or Wayland, and a desktop environment such as GNOME or KDE Plasma. Distributions intended for servers may omit graphics altogether, or include a solution stack such as LAMP. Because Linux is freely redistributable, anyone may create a distribution for any purpose. Linux was originally developed for personal computers based on the Intel x86 architecture, but has since been ported to more platforms than any other operating system. Because of the dominance of the Linux-based Android on smartphones, Linux also has the largest installed base of all general-purpose operating systems. Although it is used by only around 2.3 percent of desktop computers, the Chromebook, which runs the Linux kernel-based Chrome OS, dominates the US K–12 education market and represents nearly 20 percent of sub-$300 notebook sales in the US. Linux is the leading operating system on servers (over 96.4% of the top 1 million web servers' operating systems are Linux), leads other big iron systems such as mainframe computers, and is the only OS used on TOP500 supercomputers (since November 2017, having gradually eliminated all competitors). Linux also runs on embedded systems, i.e. devices whose operating system is typically built into the firmware and is highly tailored to the system. This includes routers, automation controls, smart home technology (like Google Nest), televisions (Samsung and LG Smart TVs use Tizen and WebOS, respectively), automobiles (for example, Tesla, Audi, Mercedes-Benz, Hyundai, and Toyota all rely on Linux), digital video recorders, video game consoles, and smartwatches. The Falcon 9's and the Dragon 2's avionics use a customized version of Linux. Linux is one of the most prominent examples of free and open-source software collaboration. The source code may be used, modified and distributed commercially or non-commercially by anyone under the terms of its respective licenses, such as the GNU General Public License. 90% of all cloud infrastructure is powered by Linux including supercomputers and cloud providers. 74% of smartphones in the world are Linux-based. KDE Plasma 5 KDE Plasma 5 is the fifth and current generation of the graphical workspaces environment created by KDE primarily for Linux systems. KDE Plasma 5 is the successor of KDE Plasma 4 and was first released on 15 July 2014. It includes a new default theme, known as "Breeze", as well as increased convergence across different devices. The graphical interface was fully migrated to QML, which uses OpenGL for hardware acceleration, which resulted in better performance and reduced power consumption. FreeBSD FreeBSD is a free and open-source Unix-like operating system descended from the Berkeley Software Distribution (BSD), which was based on Research Unix. The first version of FreeBSD was released in 1993. In 2005, FreeBSD was the most popular open-source BSD operating system, accounting for more than three-quarters of all installed simply, permissively licensed BSD systems. FreeBSD has similarities with Linux, with two major differences in scope and licensing: FreeBSD maintains a complete system, i.e. the project delivers a kernel, device drivers, userland utilities, and documentation, as opposed to Linux only delivering a kernel and drivers, and relying on third-parties for system software;and FreeBSD source code is generally released under a permissive BSD license, as opposed to the copyleft GPL used by Linux. The FreeBSD project includes a security team overseeing all software shipped in the base distribution. A wide range of additional third-party applications may be installed using the pkg package management system or FreeBSD Ports, or by compiling source code. Much of FreeBSD's codebase has become an integral part of other operating systems such as Darwin (the basis for macOS, iOS, iPadOS, watchOS, and tvOS), TrueNAS (an open-source NAS/SAN operating system), and the system software for the PlayStation 3 and PlayStation 4 game consoles. Google Chrome OS 'Chrome OS (sometimes styled as chromeOS) is a Gentoo Linux-based operating system designed by Google. It is derived from the free software Chromium OS and uses the Google Chrome web browser as its principal user interface. However, Chrome OS is proprietary software. Google announced the project in July 2009, conceiving it as an operating system in which both applications and user data reside in the cloud: hence Chrome OS primarily runs web applications. Source code and a public demo came that November. The first Chrome OS laptop, known as a Chromebook, arrived in May 2011. Initial Chromebook shipments from Samsung and Acer occurred in July 2011. Chrome OS has an integrated media player and file manager. It supports Chrome Apps, which resemble native applications, as well as remote access to the desktop. Reception was initially skeptical, with some observers arguing that a browser running on any operating system was functionally equivalent. As more Chrome OS machines have entered the market, the operating system is now seldom evaluated apart from the hardware that runs it. Android applications started to become available for the operating system in 2014, and in 2016, access to Android apps in Google Play's entirety was introduced on supported Chrome OS devices. Support for a Linux terminal and applications, known as Project Crostini, was released to the stable channel in Chrome OS 69. This was made possible via a lightweight Linux kernel that runs containers inside a virtual machine. Chrome OS is only available pre-installed on hardware from Google manufacturing partners, but there are unofficial methods that allow it to be installed in other equipment. Its open-source upstream, Chromium OS, can be compiled from downloaded source code. Early on, Google provided design goals for Chrome OS, but has not otherwise released a technical description. Other operating systems See also Comparison of operating systems Hypervisor Interruptible operating system List of important publications in operating systems List of operating systems List of pioneers in computer science Live CD Glossary of operating systems terms Microcontroller Mobile device Mobile operating system Network operating system Object-oriented operating system Operating System Projects System Commander System image Timeline of operating systems Usage share of operating systems Notes References Nav boxes Operating systems Operating systems

Operating System (OS)

Windows 10 Windows 10 is a major release of Microsoft's Windows NT operating system. It is the direct successor to Windows 8.1, which was released nearly two years earlier. It was released to manufacturing on July 15, 2015, and later to retail on July 29, 2015. Windows 10 was made available for download via MSDN and TechNet, as a free upgrade for retail copies of Windows 8 and Windows 8.1 users via the Windows Store, and to Windows 7 users via Windows Update. Windows 10 receives new builds on an ongoing basis, which are available at no additional cost to users, in addition to additional test builds of Windows 10, which are available to Windows Insiders. Devices in enterprise environments can receive these updates at a slower pace, or use long-term support milestones that only receive critical updates, such as security patches, over their ten-year lifespan of extended support. Windows 10 received generally positive reviews upon its original release. Critics praised Microsoft's decision to provide the desktop-oriented interface in line with previous versions of Windows, contrasting the tablet-oriented approach of Windows 8, although Windows 10's touch-oriented user interface mode was criticized for containing regressions upon the touch-oriented interface of its predecessor. Critics also praised the improvements to Windows 10's bundled software over Windows 8.1, Xbox Live integration, as well as the functionality and capabilities of the Cortana personal assistant and the replacement of Internet Explorer with Microsoft Edge. However, media outlets have been critical of the changes to operating system behaviors, including mandatory update installation, privacy concerns over data collection performed by the OS for Microsoft and its partners, and adware-like tactics used to promote the operating system on its release. Microsoft initially aimed to have Windows 10 installed on over one billion devices within three years of its release; that goal was ultimately reached almost five years after release on March 16, 2020. By January 2018, Windows 10 surpassed Windows 7 as the most popular version of Windows worldwide. , it is estimated that 82% of Windows PCs, 61% of all PCs (the rest being older Windows versions and other operating systems such as macOS and Linux), and 27% of all devices (including mobile, tablet and console) are running Windows 10. On June 24, 2021, Microsoft announced Windows 10's successor, Windows 11, which was released on October 5, 2021. Windows 10 is the final version of Windows which supports 32-bit processors (IA-32 and ARMv7-based) and devices with BIOS firmware. Its successor, Windows 11, requires a device that uses UEFI firmware and a 64-bit processor in any supported architecture (x86-64 and ARMv8), though certain workarounds exist that can be used to install it on devices with legacy BIOS firmware. Development At the Microsoft Worldwide Partner Conference in 2011, Andrew Lees, the chief of Microsoft's mobile technologies, said that the company intended to have a single software ecosystem for PCs, phones, tablets, and other devices: "We won't have an ecosystem for PCs, and one for phones, and one for tabletsthey'll all come together." In December 2013, technology writer Mary Jo Foley reported that Microsoft was working on an update to Windows 8 codenamed "Threshold", after a planet in its Halo franchise. Similarly to "Blue" (which became Windows 8.1), Foley described Threshold, not as a single operating system, but as a "wave of operating systems" across multiple Microsoft platforms and services, quoting Microsoft sources, scheduled for the second quarter of 2015. She also stated that one of the goals for Threshold was to create a unified application platform and development toolkit for Windows, Windows Phone and Xbox One (which all use a similar kernel based on Windows NT). At the Build Conference in April 2014, Microsoft's Terry Myerson unveiled an updated version of Windows 8.1 (build 9697) that added the ability to run Windows Store apps inside desktop windows and a more traditional Start menu in place of the Start screen seen in Windows 8. The new Start menu takes after Windows 7's design by using only a portion of the screen and including a Windows 7-style application listing in the first column. The second column displays Windows 8-style app tiles. Myerson said that these changes would occur in a future update, but did not elaborate. Microsoft also unveiled the concept of a "universal Windows app", allowing Windows Store apps created for Windows 8.1 to be ported to Windows Phone 8.1 and Xbox One while sharing a common codebase, with an interface designed for different device form factors, and allowing user data and licenses for an app to be shared between multiple platforms. Windows Phone 8.1 would share nearly 90% of the common Windows Runtime APIs with Windows 8.1 on PCs. Screenshots of a Windows build purported to be Threshold were leaked in July 2014, showing the previously presented Start menu and windowed Windows Store apps, followed by a further screenshot of a build identifying itself as "Windows Technical Preview", numbered 9834, in September 2014, showing a new virtual desktop system, a notification center, and a new File Explorer icon. Announcement On September 30, 2014, Microsoft officially announced that Threshold would be unveiled during a media event as Windows 10. Myerson said that Windows 10 would be Microsoft's "most comprehensive platform ever", providing a single, unified platform for desktop and laptop computers, tablets, smartphones, and all-in-one devices. He emphasized that Windows 10 would take steps towards restoring user interface mechanics from Windows 7 to improve the experience for users on non-touch devices, noting criticism of Windows 8's touch-oriented interface by keyboard and mouse users. Despite these concessions, Myerson noted that the touch-optimized interface would evolve as well on 10. In regards to Microsoft naming the new operating system Windows 10 instead of Windows 9, Terry Myerson said that "based on the product that's coming, and just how different our approach will be overall, it wouldn't be right to call it Windows 9." He also joked that they could not call it "Windows One" (alluding to several recent Microsoft products with a similar brand, such as OneDrive, OneNote, and the Xbox One) because Windows 1.0 already existed. At a San Francisco conference in October 2014, Tony Prophet, Microsoft's Vice President of Windows Marketing, said that Windows 9 "came and went", and that Windows 10 would not be "an incremental step from Windows 8.1," but "a material step. We're trying to create one platform, one eco-system that unites as many of the devices from the small embedded Internet of Things, through tablets, through phones, through PCs and, ultimately, into the Xbox." Further details surrounding Windows 10's consumer-oriented features were presented during another media event held on January 21, 2015, entitled "Windows 10: The Next Chapter". The keynote featured the unveiling of Cortana integration within the operating system, new Xbox-oriented features, Windows 10 Mobile, an updated Office Mobile suite, Surface Huba large-screened Windows 10 device for enterprise collaboration based upon Perceptive Pixel technology, along with HoloLens‑augmented reality eyewear and an associated platform for building apps that can render holograms through HoloLens. Additional developer-oriented details surrounding the "Universal Windows Platform" concept were revealed and discussed during Microsoft's Build developers' conference. Among them were the unveiling of "Islandwood", which provides a middleware toolchain for compiling Objective-C-based software (particularly iOS) to run as universal apps on Windows 10 and Windows 10 Mobile. A port of Candy Crush Saga made using the toolkit, which shared much of its code with the iOS version, was demonstrated, alongside the announcement that the King-developed game would be bundled with Windows 10 at launch. At the 2015 Ignite conference, Microsoft employee Jerry Nixon stated that Windows 10 would be the "last version of Windows", a statement that Microsoft confirmed was "reflective" of its view of the operating system being a "service" with new versions and updates to be released over time. In 2021, however, Microsoft announced that Windows 10 would be succeeded on compatible hardware by Windows 11–and that Windows 10 support will end on October 14, 2025. Release and marketing On June 1, 2015, Microsoft announced that Windows 10 would be released on July 29. On July 20, 2015, Microsoft began "Upgrade Your World", an advertising campaign centering on Windows 10, with the premiere of television commercials in Australia, Canada, France, Germany, Japan, the United Kingdom, and the United States. The commercials focused on the tagline "A more human way to do", emphasizing new features and technologies supported by Windows 10 that sought to provide a more "personal" experience to users. The campaign culminated with launch events in thirteen cities on July 29, 2015, which celebrated "the unprecedented role our biggest fans played in the development of Windows 10". Features Windows 10 makes its user experience and functionality more consistent between different classes of device and addresses most of the shortcomings in the user interface that were introduced in Windows 8. Windows 10 Mobile, the successor to Windows Phone 8.1, shared some user interface elements and apps with its PC counterpart. Windows 10 supports universal apps, an expansion of the Metro-style first introduced in Windows 8. Universal apps can be designed to run across multiple Microsoft product families with nearly identical codeincluding PCs, tablets, smartphones, embedded systems, Xbox One, Surface Hub and Mixed Reality. The Windows user interface was revised to handle transitions between a mouse-oriented interface and a touchscreen-optimized interface based on available input devicesparticularly on 2-in-1 PCs, both interfaces include an updated Start menu which incorporates elements of Windows 7's traditional Start menu with the tiles of Windows 8. Windows 10 also introduced the Microsoft Edge web browser, a virtual desktop system, a window and desktop management feature called Task View, support for fingerprint and face recognition login, new security features for enterprise environments, and . The Windows Runtime app ecosystem was revised into the Universal Windows Platform (UWP). These universal apps are made to run across multiple platforms and device classes, including smartphones, tablets, Xbox One consoles, and other devices compatible with Windows 10. Windows apps share code across platforms, have responsive designs that adapt to the needs of the device and available inputs, can synchronize data between Windows 10 devices (including notifications, credentials, and allowing cross-platform multiplayer for games), and are distributed through the Microsoft Store (rebranded from Windows Store since September 2017). Developers can allow "cross-buys", where purchased licenses for an app apply to all of the user's compatible devices, rather than only the one they purchased on (e.g., a user purchasing an app on PC is also entitled to use the smartphone version at no extra cost). The ARM version of Windows 10 allows running applications for x86 processors through 32-bit software emulation. On Windows 10, Microsoft Store serves as a unified storefront for apps, video content, and eBooks. Windows 10 also allows web apps and desktop software (using either Win32 or .NET Framework) to be packaged for distribution on Microsoft Store. Desktop software distributed through Windows Store is packaged using the App-V system to allow sandboxing. User interface and desktop A new iteration of the Start menu is used on the Windows 10 desktop, with a list of places and other options on the left side, and tiles representing applications on the right. The menu can be resized, and expanded into a full-screen display, which is the default option in Tablet mode. A new virtual desktop system was added by a feature known as Task View, which displays all open windows and allows users to switch between them, or switch between multiple workspaces. Universal apps, which previously could be used only in full screen mode, can now be used in self-contained windows similarly to other programs. Program windows can now be snapped to quadrants of the screen by dragging them to the corner. When a window is snapped to one side of the screen, Task View appears and the user is prompted to choose a second window to fill the unused side of the screen (called "Snap Assist"). The Windows system icons were also changed. Charms have been removed; their functionality in universal apps is accessed from an App commands menu on their title bar. In its place is Action Center, which displays notifications and settings toggles. It is accessed by clicking an icon in the notification area, or dragging from the right of the screen. Notifications can be synced between multiple devices. The Settings app (formerly PC Settings) was refreshed and now includes more options that were previously exclusive to the desktop Control Panel. Windows 10 is designed to adapt its user interface based on the type of device being used and available input methods. It offers two separate user interface modes: a user interface optimized for mouse and keyboard, and a "Tablet mode" designed for touchscreens. Users can toggle between these two modes at any time, and Windows can prompt or automatically switch when certain events occur, such as disabling Tablet mode on a tablet if a keyboard or mouse is plugged in, or when a 2-in-1 PC is switched to its laptop state. In Tablet mode, programs default to a maximized view, and the taskbar contains a back button and hides buttons for opened or pinned programs by default; Task View is used instead to switch between programs. The full screen Start menu is used in this mode, similarly to Windows 8, but scrolls vertically instead of horizontally. System security Windows 10 incorporates multi-factor authentication technology based upon standards developed by the FIDO Alliance. The operating system includes improved support for biometric authentication through the Windows Hello platform. Devices with supported cameras (requiring infrared illumination, such as Intel RealSense) allow users to log in with iris or face recognition, similarly to Kinect. Devices with supported readers allow users to log in through fingerprint recognition. Support was also added for palm-vein scanning through a partnership with Fujitsu in February 2018. Credentials are stored locally and protected using asymmetric encryption. In 2017, researchers demonstrated that Windows Hello could be bypassed on fully-updated Windows 10 1703 with a color printout of a person's picture taken with an IR camera. In 2021, researchers were again able to bypass the Windows Hello functionalities by using custom hardware disguised as a camera, which presented an IR photo of the owner's face. In addition to biometric authentication, Windows Hello supports authentication with a PIN. By default, Windows requires a PIN to consist of four digits, but can be configured to permit more complex PINs. However, a PIN is not a simpler password. While passwords are transmitted to domain controllers, PINs are not. They are tied to one device, and if compromised, only one device is affected. Backed by a Trusted Platform Module (TPM) chip, Windows uses PINs to create strong asymmetric key pairs. As such, the authentication token transmitted to the server is harder to crack. In addition, whereas weak passwords may be broken via rainbow tables, TPM causes the much-simpler Windows PINs to be resilient to brute-force attacks. When Windows 10 was first introduced, multi-factor authentication was provided by two components: Windows Hello and Passport (not to be confused with the Passport platform of 1998). Later, Passport was merged into Windows Hello. The enterprise edition of Windows 10 offers additional security features; administrators can set up policies for the automatic encryption of sensitive data, selectively block applications from accessing encrypted data, and enable Device Guarda system which allows administrators to enforce a high-security environment by blocking the execution of software that is not digitally signed by a trusted vendor or Microsoft. Device Guard is designed to protect against zero-day exploits, and runs inside a hypervisor so that its operation remains separated from the operating system itself. Command line The console windows based on Windows Console (for any console app, not just PowerShell and Windows Command Prompt) can now be resized without any restrictions, can be made to cover the full screen by pressing , and can use standard keyboard shortcuts, such as those for cut, copy, and paste. Other features such as word wrap and transparency were also added. These functions can be disabled to revert to the legacy console if needed. The Anniversary Update added Windows Subsystem for Linux (WSL), which allows the installation of a user space environment from a supported Linux distribution that runs natively on Windows. The subsystem translates Linux system calls to those of the Windows NT kernel (only claims full system call compatibility as of WSL 2, included in a later Windows update). The environment can execute the Bash shell and 64-bit command-line programs (WSL 2 also supports 32-bit Linux programs and graphics, assuming supporting software installed, and GPUs support for other uses). Windows applications cannot be executed from the Linux environment, and vice versa. Linux distributions for Windows Subsystem for Linux are obtained through Microsoft Store. The feature initially supported an Ubuntu-based environment; Microsoft announced in May 2017 that it would add Fedora and OpenSUSE environment options as well. Storage requirements To reduce the storage footprint of the operating system, Windows 10 automatically compresses system files. The system can reduce the storage footprint of Windows by approximately 1.5GB for 32-bit systems and 2.6GB for 64-bit systems. The level of compression used is dependent on a performance assessment performed during installations or by OEMs, which tests how much compression can be used without harming operating system performance. Furthermore, the Refresh and Reset functions use runtime system files instead, making a separate recovery partition redundant, allowing patches and updates to remain installed following the operation, and further reducing the amount of space required for Windows 10 by up to 12GB. These functions replace the WIMBoot mode introduced on Windows 8.1 Update, which allowed OEMs to configure low-capacity devices with flash-based storage to use Windows system files out of the compressed WIM image typically used for installation and recovery. Windows 10 also includes a function in its Settings app that allows users to view a breakdown of how their device's storage capacity is being used by different types of files, and determine whether certain types of files are saved to internal storage or an SD card by default. Online services and functionality Windows 10 introduces Microsoft Edge, a new default web browser. It initially featured a new standards-compliant rendering engine derived from Trident, and also includes annotation tools and integration with other Microsoft platforms present within Windows 10. Internet Explorer 11 is maintained on Windows 10 for compatibility purposes, but is deprecated in favor of Edge and will no longer be actively developed. In January 2020, the initial version of Edge was succeeded by a new iteration derived from the Chromium project and the Blink layout engine and the old Edge based on EdgeHTML is now called 'Microsoft Edge Legacy'. The legacy version of Edge is currently being replaced by the new Chromium-based Edge via Windows Update, though this version can also be downloaded manually. Every Windows 10 version from 20H2, which was released on October 20, 2020, will come with the new version of the browser preinstalled. The Windows 10 October 2020 update added a price comparison tool to the Edge browser. Windows 10 incorporates a universal search box located alongside the Start and Task View buttons, which can be hidden or condensed into a single button. Previous versions featured Microsoft's intelligent personal assistant Cortana, which was first introduced with Windows Phone 8.1 in 2014, and supports both text and voice input. Many of its features are a direct carryover from Windows Phone, including integration with Bing, setting reminders, a Notebook feature for managing personal information, as well as searching for files, playing music, launching applications and setting reminders or sending emails. Since the November 2019 update, Microsoft has begun to downplay Cortana as part of a repositioning of the product towards enterprise use, with the May 2020 update removing its Windows shell integration and consumer-oriented features. Microsoft Family Safety is replaced by Microsoft Family, a parental controls system that applies across Windows platforms and Microsoft online services. Users can create a designated family, and monitor and restrict the actions of users designated as children, such as access to websites, enforcing age ratings on Microsoft Store purchases, and other restrictions. The service can also send weekly e-mail reports to parents detailing a child's computer usage. Unlike previous versions of Windows, child accounts in a family must be associated with a Microsoft accountwhich allows these settings to apply across all Windows 10 devices that a particular child is using. Windows 10 also offers the Wi-Fi Sense feature originating from Windows Phone 8.1; users can optionally have their device automatically connect to suggested open hotspots, and share their home network's password with contacts (either via Skype, People, or Facebook) so they may automatically connect to the network on a Windows 10 device without needing to manually enter its password. Credentials are stored in an encrypted form on Microsoft servers and sent to the devices of the selected contacts. Passwords are not viewable by the guest user, and the guest user is not allowed to access other computers or devices on the network. Wi-Fi Sense is not usable on 802.1X-encrypted networks. Adding "_optout" at the end of the SSID will also block the corresponding network from being used for this feature. Universal calling and messaging apps for Windows 10 are built in as of the November 2015 update: Messaging, Skype Video, and Phone. These offer built-in alternatives to the Skype download and sync with Windows 10 Mobile. Multimedia and gaming Windows 10 provides greater integration with the Xbox ecosystem. Xbox SmartGlass is succeeded by the Xbox Console Companion (formerly the Xbox app), which allows users to browse their game library (including both PC and Xbox console games), and Game DVR is also available using a keyboard shortcut, allowing users to save the last 30 seconds of gameplay as a video that can be shared to Xbox Live, OneDrive, or elsewhere. Windows 10 also allows users to control and play games from an Xbox One console over a local network. The Xbox Live SDK allows application developers to incorporate Xbox Live functionality into their apps, and future wireless Xbox One accessories, such as controllers, are supported on Windows with an adapter. Microsoft also intends to allow cross-purchases and save synchronization between Xbox One and Windows 10 versions of games; Microsoft Studios games such as ReCore and Quantum Break are intended as being exclusive to Windows 10 and Xbox One. Candy Crush Saga and Microsoft Solitaire Collection are also automatically installed upon installation of Windows 10. Windows 10 adds native game recording and screenshot capture ability using the newly introduced Game Bar. Users can also have the OS continuously record gameplay in the background, which then allows the user to save the last few moments of gameplay to the storage device. Windows 10 adds FLAC and HEVC codecs and support for the Matroska media container, allowing these formats to be opened in Windows Media Player and other applications. DirectX 12 Windows 10 includes DirectX 12, alongside WDDM 2.0. Unveiled March 2014 at GDC, DirectX 12 aims to provide "console-level efficiency" with "closer to the metal" access to hardware resources, and reduced CPU and graphics driver overhead. Most of the performance improvements are achieved through low-level programming, which allow developers to use resources more efficiently and reduce single-threaded CPU bottlenecking caused by abstraction through higher level APIs. DirectX 12 will also feature support for vendor agnostic multi-GPU setups. WDDM 2.0 introduces a new virtual memory management and allocation system to reduce workload on the kernel-mode driver. Fonts Windows 10 adds three new default typefaces compared to Windows 8, but removes dozens of others. The removed typefaces are available in supplemental packs and may be added manually over a non-metered internet connection. Editions and pricing Windows 10 is available in five main editions for personal computing devices; the Home and Pro editions of which are sold at retail in most countries, and as pre-loaded software on new computers. Home is aimed at home users, while Pro is aimed at power users and small businesses. Each edition of Windows 10 includes all of the capabilities and features of the edition below it, and add additional features oriented towards their market segments; for example, Pro adds additional networking and security features such as BitLocker, Device Guard, Windows Update for Business, and the ability to join a domain. Enterprise and Education, the other editions, contain additional features aimed towards business environments, and are only available through volume licensing. As part of Microsoft's unification strategies, Windows products that are based on Windows 10's common platform but meant for specialized platforms are marketed as editions of the operating system, rather than as separate product lines. An updated version of Microsoft's Windows Phone operating system for smartphones, and also tablets, was branded as Windows 10 Mobile. Editions of Enterprise and Mobile will also be produced for embedded systems, along with Windows 10 IoT Core, which is designed specifically for use in small footprint, low-cost devices and Internet of Things (IoT) scenarios and is similar to Windows Embedded. On May 2, 2017, Microsoft unveiled Windows 10 S (referred to in leaks as Windows 10 Cloud), a feature-limited edition of Windows 10 which was designed primarily for devices in the education market (competing, in particular, with Chrome OS netbooks), such as the Surface Laptop that Microsoft also unveiled at this time. The OS restricts software installation to applications obtained from Microsoft Store; the device may be upgraded to Windows 10 Pro for a fee to enable unrestricted software installation. As a time-limited promotion, Microsoft stated that this upgrade would be free on the Surface Laptop until March 31, 2018. Windows 10 S also contains a faster initial setup and login process, and allows devices to be provisioned using a USB drive with the Windows Intune for Education platform. In March 2018, Microsoft announced that Windows 10 S would be deprecated because of market confusion and would be replaced by "S Mode", an OEM option wherein Windows defaults to only allowing applications to be installed from Microsoft Store, but does not require payment in order to disable these restrictions. Preview releases A public beta program for Windows10 known as the Windows Insider Program began with the first publicly available preview release on October 1, 2014. Insider preview builds are aimed towards enthusiasts and enterprise users for the testing and evaluation of updates and new features. Users of the Windows Insider program receive occasional updates to newer preview builds of the operating system and will continue to be able to evaluate preview releases after general availability (GA) in July 2015this is in contrast to previous Windows beta programs, where public preview builds were released less frequently and only during the months preceding GA. Windows Insider builds continued being released after the release to manufacturing (RTM) of Windows10. Public release On July 29, 2015, Microsoft officially announced that Windows 10 would be released for retail purchase as a free upgrade from earlier versions of Windows. In comparison to previous Windows releases, which had a longer turnover between the release to manufacturing (RTM) and general release to allow for testing by vendors (and in some cases, the development of "upgrade kits" to prepare systems for installation of the new version), an HP executive explained that because it knew Microsoft targeted the operating system for a 2015 release, the company was able to optimize its then-current and upcoming products for Windows 10 in advance of its release, negating the need for such a milestone. The general availability build of Windows10, numbered 10240, was first released to Windows Insider channels for pre-launch testing on July 15, 2015, prior to its formal release. Although a Microsoft official said there would be no specific RTM build of Windows 10, 10240 was described as an RTM build by media outlets because it was released to all Windows Insider members at once (rather than to users on the "Fast ring" first), it no longer carried pre-release branding and desktop watermark text, and its build number had mathematical connections to the number10 in reference to the operating system's naming. The Enterprise edition was released to volume licensing on August 1, 2015. Windows 10 is distributed digitally through the "Media Creation Tool", which is functionally identical to the Windows 8 online installer, and can also be used to generate an ISO image or USB install media. In-place upgrades are supported from most editions of Windows 7 with Service Pack 1 and Windows8.1 with Update 1, while users with Windows8 must first upgrade to Windows8.1. Changing between architectures (e.g., upgrading from 32-bit edition to a 64-bit editions) via in-place upgrades is not supported; a clean install is required. In-place upgrades may be rolled back to the device's previous version of Windows, provided that 30days have not passed since installation, and backup files were not removed using Disk Cleanup. Windows 10 was available in 190countries and 111 languages upon its launch, and as part of efforts to "re-engage" with users in China, Microsoft also announced that it would partner with Qihoo and Tencent to help promote and distribute Windows10 in China, and that Chinese PC maker Lenovo would provide assistance at its service centers and retail outlets for helping users upgrade to Windows10. At retail, Windows 10 is priced similarly to editions of Windows 8.1, with U.S. prices set at $119 and $199 for Windows 10Home and Pro respectively. A Windows 10 Pro Pack license allows upgrades from Windows 10 Home to Windows 10 Pro. Retail copies only ship on USB flash drive media; however, system builder copies still ship as DVD-ROM media. New devices shipping with Windows10 were also released during the operating system's launch window. Windows RT devices cannot be upgraded to Windows10. Free upgrade offer During its first year of availability, upgrade licenses for Windows10 could be obtained at no charge for devices with a genuine license for an eligible edition of Windows7 or8.1. This offer did not apply to Enterprise editions, as customers under an active Software Assurance (SA)contract with upgrade rights are entitled to obtain Windows 10 Enterprise under their existing terms. All users running non-genuine copies of Windows, and those without an existing Windows7 or8 license, were ineligible for this promotion; although upgrades from a non-genuine version were possible, they result in a non-genuine copy of10. On the general availability build of Windows10 (version 1507), to activate and generate the "digital entitlement" for Windows10, the operating system must have first been installed as an in-place upgrade. During the free upgrade, a genuineticket.xml file is created in the background and the system's motherboard details are registered with a Microsoft Product Activation server. Once installed, the operating system can be reinstalled on that particular system via normal means without a product key, and the system's license will automatically be detected via online activation - in essence, the Microsoft Product Activation Server will remember the system's motherboard and give it the green light for product re-activation. Because of installation issues with Upgrade Only installs, the November Update (version 1511) included additional activation mechanisms. This build treated Windows7 and Windows8/8.1 product keys as Windows10 product keys, meaning they could be entered during installation to activate the free license, without the need to upgrade first to "activate" the hardware with Microsoft's activation servers. For major Original Equipment Manufacturers (OEMs), Windows 8/8.1 and Windows 10 OEM product keys are embedded in the firmware of the motherboard and if the correct edition of Windows 10 is present on the installation media, they are automatically inputted during installation. Since the release of the Fall Creators Update (version 1709), Microsoft decided to release multi-edition installation media, to alleviate installation and product activation issues users experienced because of accidentally installing the wrong edition of Windows 10. The Windows Insider Preview version of Windows10 automatically updated itself to the generally released version as part of the version progression and continues to be updated to new beta builds, as it had throughout the testing process. Microsoft explicitly stated that Windows Insider was not a valid upgrade path for those running a version of Windows that is ineligible for the upgrade offer; although, if it was not installed with a license carried over from an in-place upgrade to 10 Insider Preview from Windows7 or8, the Insider Preview does remain activated as long as the user does not exit the Windows Insider program. The offer was promoted and delivered via the "Get Windows10" application (also known as GWX), which was automatically installed via Windows Update ahead of Windows 10's release, and activated on systems deemed eligible for the upgrade offer. Via a notification area icon, users could access an application that advertised Windows10 and the free upgrade offer, check device compatibility, and "reserve" an automatic download of the operating system upon its release. On July 28, a pre-download process began in which Windows10 installation files were downloaded to some computers that had reserved it. Microsoft said that those who reserved Windows10 would be able to install it through GWX in a phased rollout process. The operating system could alternatively be downloaded at any time using a separate "Media Creation Tool" setup program, that allows for the creation of DVD or USB installation media. In May 2016, Microsoft announced that the free upgrade offer would be extended to users of assistive technologies; however, Microsoft did not implement any means of certifying eligibility for this offer, which some outlets thereby promoted as being a loophole to fraudulently obtain a free Windows 10 upgrade. Microsoft said that the loophole is not intended to be used in this manner. In November 2017, Microsoft announced that this program would end on December 31, 2017. However, another loophole was found that allowed Windows 7 and 8.1 users upgrade to Windows 10 using existing licenses, even though the free upgrade offers officially ended in 2017. No word from Microsoft was given whether it will be closed and some outlets have continued to promote it as a free method of upgrading from the now-unsupported Windows 7. Licensing During upgrades, Windows10 licenses are not tied directly to a product key. Instead, the license status of the system's current installation of Windows is migrated, and a "Digital license" ( known as "Digital entitlement" in version 1511 or earlier) is generated during the activation process, which is bound to the hardware information collected during the process. If Windows10 is reinstalled cleanly and there have not been any significant hardware changes since installation (such as a motherboard change), the online activation process will automatically recognize the system's digital entitlement if no product key is entered during installations. However, unique product keys are still distributed within retail copies of Windows10. As with previous non-volume-licensed variants of Windows, significant hardware changes will invalidate the digital entitlement, and require Windows to be re-activated. Updates and support Unlike previous versions of Windows, Windows Update does not allow the selective installation of updates, and all updates (including patches, feature updates, and driver software) are downloaded and installed automatically. Users can only choose whether their system will reboot automatically to install updates when the system is inactive, or be notified to schedule a reboot. If a wireless network is designated as "Metered"—a function which automatically reduces the operating system's background network activity to conserve limits on Internet usage—most updates are not downloaded until the device is connected to a non-metered network. Version 1703 allows wired (Ethernet) networks to be designated as metered, but Windows may still download certain updates while connected to a metered network. In version 2004, by installing the August 2020 security update and later versions, driver and non-security updates pushed via Windows Update that are considered optional are no longer automatically downloaded and installed in their devices. Users can access them on Settings > Update & Security > Windows Update > View optional update. Updates can cause compatibility or other problems; a Microsoft troubleshooter program allows bad updates to be uninstalled. Under the Windows end-user license agreement, users consent to the automatic installation of all updates, features and drivers provided by the service, and implicitly consent "without any additional notice" to the possibility of features being modified or removed. The agreement also states, specifically for users of Windows10 in Canada, that they may pause updates by disconnecting their device from the Internet. Windows Update can also use a peer to peer system for distributing updates; by default, users' bandwidth is used to distribute previously downloaded updates to other users, in combination with Microsoft servers. Users can instead choose to only use peer-to-peer updates within their local area network. Support lifecycle The original release of Windows 10 receives mainstream support for five years after its original release, followed by five years of extended support, but this is subject to conditions. Microsoft's support lifecycle policy for the operating system notes that "Updates are cumulative, with each update built upon all of the updates that preceded it", that "a device needs to install the latest update to remain supported", and that a device's ability to receive future updates will depend on hardware compatibility, driver availability, and whether the device is within the OEM's "support period"a new aspect not accounted for in lifecycle policies for previous versions. This policy was first invoked in 2017 to block Intel Clover Trail devices from receiving the Creators Update, as Microsoft asserts that future updates "require additional hardware support to provide the best possible experience", and that Intel no longer provided support or drivers for the platform. Microsoft stated that these devices would no longer receive feature updates, but would still receive security updates through January 2023. Microsoft will continue to support at least one standard Windows 10 release until October 14, 2025. The following table collects current status of the aforementioned updating and support of different branches of Windows 10: Feature updates Windows 10 is often described by Microsoft as being a "service", as it receives regular "feature updates" that contain new features and other updates and fixes. In April 2017, Microsoft stated that these updates would be released twice a year every March and September in the future. Mainstream builds of Windows 10, until and including 2004, were labeled "YYMM", with "YY" representing the two-digit year and "MM" representing the month of release. For example, version 1809 was released in September (the ninth month) of 2018. This was changed with the 20H2 release where "MM" represents the half of the year in which the update was released, for example H1 for the first half and H2 for the second half. The pace at which feature updates are received by devices is dependent on which release channel is used. The default branch for all users of Windows10 Home and Pro is "Semi-Annual Channel (Targeted)" (formerly "Current Branch", or "CB"), which receives stable builds after they are publicly released by Microsoft. Each build of Windows 10 is supported for 18 months after its original release. In enterprise environments, Microsoft officially intends that this branch is used for "targeted" deployments of newly released stable versions so that they can be evaluated and tested on a limited number of devices before a wider deployment. Once a stable build is certified by Microsoft and its partners as being suitable for broad deployment, the build is then released on the "Semi-Annual Channel" (formerly "Current Branch for Business", or "CBB"), which is supported by the Pro and Enterprise editions of Windows 10. Semi-Annual Channel receives stable builds on a four-month delay from their release on the Targeted channel, Administrators can also use the "Windows Update for Business" system, as well as existing tools such as WSUS and System Center Configuration Manager, to organize structured deployments of feature updates across their networks. The Windows Insider branches receive unstable builds as they are released; it is divided into two channels, "Dev" (which receives new builds immediately after their release), and "Beta" (whose releases are slightly delayed from their "Dev" release). Enterprise licensees may use the Windows 10 Enterprise LTSC (formerly LTSB) edition, where "LTSC" stands for "long-term servicing channel", which only receive quality of life updates (i.e. security patches), and has a full, 5 or 10-year support lifecycle for each build. This edition is designed for "special-purpose devices" that perform a fixed function (such as automated teller machines and medical equipment). For this reason, it excludes Cortana, Microsoft Store, and all bundled Universal Windows Platform apps (including but not limited to Microsoft Edge, hence these builds ship only with Internet Explorer as browser). Microsoft director Stella Chernyak explained that "we have businesses [that] may have mission-critical environments where we respect the fact they want to test and stabilize the environment for a long time." Four LTSC builds have been released, correlating with the 1507, 1607, 1809, and 21H2 versions of Windows 10, respectively. In July 2017, Microsoft announced changes in the terminology for Windows branches as part of its effort to unify the update cadence with that of Office 365 ProPlus and Windows Server 2016. The branch system now defines two paces of upgrade deployment in enterprise environments, "targeted" initial deployment of a new version on selected systems immediately after its stable release for final testing, and "broad" deployment afterwards. Hence, "Current Branch" is now known as "Semi-Annual Channel (Targeted)", and "Current Branch for Business" for broad deployment is now referred to as "Semi-Annual Channel". In February 2019, Microsoft announced changes again in delivering updates in beginning of release of version 1903: a single SAC will be released and SAC-T will be retired, and users are no longer able to switch to different channels. Instead, these updates can be deferred from 30 to 90 days, or depending how the device was configured to deferred the updates. In April 2019, it was announced that, in addition, feature updates will no longer be automatically pushed to users. However, after the release of version 2004, the update only pushed for those running a feature update version that is nearing end of service or it can be paused for up to 35 days. Feature updates prior to version 1909 are distributed solely as an in-place upgrade installation, requiring the download of a complete operating system package (approximately 3.5 GB in size for 64-bit systems). Unlike previous builds, version 1909 is designed primarily as an update rollup version of 1903, focusing primarily on minor feature additions and enhancements. For upgrades to 1909 from 1903, a new delivery method is used where its changes were delivered as part of the monthly cumulative update, but are left in a dormant state until the 1909 update "enablement" patch is installed. The full upgrade process is still used for those using builds prior to 1903. Features in development In May 2017, Microsoft unveiled Fluent Design System (previously codenamed "Project Neon"), a revamp of Microsoft Design Language 2 that will include guidelines for the designs and interactions used within software designed for all Windows 10 devices and platforms. The new design language will include the more prominent use of motion, depth, and translucency effects. Microsoft stated that the implementation of this design language would be performed over time, and it had already started to implement elements of it in Creators Update and Fall Creators Update. On December 7, 2016, Microsoft announced that, as part of a partnership with Qualcomm, it planned to introduce support for running Win32 software on ARM architecture with a 32-bit x86 processor emulator, in 2017. Terry Myerson stated that this move would enable the production of Qualcomm Snapdragon-based Windows devices with cellular connectivity and improved power efficiency over Intel-compatible devices, and still capable of running the majority of existing Windows software (unlike the previous Windows RT, which was restricted to Windows Store apps). Microsoft is initially targeting this project towards laptops. Microsoft launched the branding Always Connected PCs in December 2017 to market Windows 10 devices with cellular connectivity, which included two ARM-based 2-in-1 laptops from Asus and HP featuring the Snapdragon 835 system-on-chip, and the announcement of a partnership between AMD and Qualcomm to integrate its Snapdragon X16 gigabit LTE modem with AMD's Ryzen Mobile platform. In August 2019, Microsoft began testing changes to its handling of the user interface on convertible devices—downplaying the existing "Tablet Mode" option in favor of presenting the normal desktop with optimizations for touch when a keyboard is not present, such as increasing the space between taskbar buttons and displaying the virtual keyboard when text fields are selected. In April 2021, the ability to run Linux applications using a graphical user interface, such as Audacity, directly in Windows, was introduced as a preview. This feature would later be included as part of the updated Windows Subsystem for Linux 2 for Windows 11 only. System requirements The basic hardware requirements to install Windows 10 were initially the same as those for Windows 8.1 and Windows 8, and only slightly higher than for Windows 7 and Windows Vista. As of the May 2019 update, the minimum disk space requirement has been increased to 32 GB. In addition, on new installations, Windows permanently reserves up to 7 GB of disk space in order to ensure proper installation of future feature updates. The 64-bit variants require a CPU that supports certain instructions. Devices with low storage capacity must provide a USB flash drive or SD card with sufficient storage for temporary files during upgrades. Some pre-built devices may be described as "certified" by Microsoft. Certified tablets must include , , and keys; and keys are no longer required. As with Windows 8, all certified devices must ship with UEFI Secure Boot enabled by default. Unlike Windows 8, OEMs are no longer required to make Secure Boot settings user-configurable, meaning that devices may optionally be locked to run only Microsoft-signed operating systems. A supported infrared-illuminated camera is required for Windows Hello face authentication, and a supported fingerprint reader is required for Windows Hello fingerprint authentication. Device Guard requires a UEFI system with no third-party certificates loaded, and CPU virtualization extensions (including SLAT and IOMMU) enabled in firmware. Beginning with Intel Kaby Lake and AMD Bristol Ridge, Windows 10 is the only version of Windows that Microsoft will officially support on newer CPU microarchitectures. Terry Myerson stated that Microsoft did not want to make further investments in optimizing older versions of Windows and associated software for newer generations of processors. These policies were criticized by the media, who especially noted that Microsoft was refusing to support newer hardware (particularly Intel's Skylake CPUs, which was also originally targeted by the new policy with a premature end of support that was ultimately retracted) on Windows 8.1, a version of Windows that was still in mainstream support until January 2018. In addition, an enthusiast-created modification was released that disabled the check and allowed Windows 8.1 and earlier to continue to work on the platform. Windows 10 version 1703 and later do not support Intel Clover Trail system-on-chips, per Microsoft's stated policy of only providing updates for devices during their OEM support period. Starting with Windows 10 version 2004, Microsoft will require new OEM devices to use 64-bit processors, and will therefore cease the distribution of x86 (32-bit) variants of Windows 10 via OEM channels. The 32-bit variants of Windows 10 will remain available via non-OEM channels, and Microsoft will continue to "[provide] feature and security updates on these devices". This would later be followed by Windows 11 dropping 32-bit hardware support altogether, and thus making Windows 10 the final version of Windows to have a 32-bit version. Reception Critics characterized the initial release of Windows 10 as being rushed, citing the incomplete state of some of the operating system's bundled software, such as the Edge web browser, as well as the stability of the operating system itself on launch. However, TechRadar felt that it could be "the new Windows 7", citing the operating system's more familiar user interface, improvements to bundled apps, performance improvements, a "rock solid" search system, and the Settings app being more full-featured than its equivalents on8 and8.1. The Edge browser was praised for its performance, although it was not in a feature-complete state at launch. While considering them a "great idea in principle", concerns were shown for Microsoft's focus on the universal app ecosystem: It's by no means certain that developers are going to flock to Windows10 from iOS and Android simply because they can convert their apps easily. It may well become a no-brainer for them, but at the moment a conscious decision is still required. Engadget was similarly positive, noting that the upgrade process was painless and that Windows10's user interface had balanced aspects of Windows8 with those of previous versions with a more mature aesthetic. Cortana's always-on voice detection was considered to be its "true strength", also citing its query capabilities and personalization features, but noting that it was not as pre-emptive as Google Now. Windows10's stock applications were praised for being improved over their Windows 8 counterparts, and for supporting windowed modes. The Xbox app was also praised for its Xbox One streaming functionality, although recommending its use over a wired network because of inconsistent quality over Wi-Fi. In conclusion, it was argued that "Windows10 delivers the most refined desktop experience ever from Microsoft, and yet it's so much more than that. It's also a decent tablet OS, and it's ready for a world filled with hybrid devices. And, barring another baffling screwup, it looks like a significant step forward for mobile. Heck, it makes the Xbox One a more useful machine." Ars Technica panned the new Tablet mode interface for removing the charms and app switching, making the Start button harder to use by requiring users to reach for the button on the bottom-left rather than at the center of the screen when swiping with a thumb, and for making application switching less instantaneous through the use of Task View. Microsoft Edge was praised for being "tremendously promising", and "a much better browser than Internet Explorer ever was", but criticized it for its lack of functionality on-launch. In conclusion, contrasting Windows8 as being a "reliable" platform albeit consisting of unfinished concepts, Windows10 was considered "the best Windows yet", and was praised for having a better overall concept in its ability to be "comfortable and effective" across a wide array of form factors, but that it was buggier than previous versions of Windows were on-launch. ExtremeTech felt that Windows10 restricted the choices of users, citing its more opaque setting menus, forcing users to give up bandwidth for the peer-to-peer distribution of updates, and for taking away user control of specific functions, such as updates, explaining that "it feels, once again, as if Microsoft has taken the seed of a good idea, like providing users with security updates automatically, and shoved the throttle to maximum." Windows 10 has also received criticism because of deleting files without user permission after auto updates. Critics have noted that Windows10 heavily emphasizes freemium services, and contains various advertising facilities. Some outlets have considered these to be a hidden "cost" of the free upgrade offer. Examples of these have included microtransactions in bundled games such as Microsoft Solitaire Collection, default settings that display promotions of "suggested" apps in the Start menu, "tips" on the lock screen that may contain advertising, ads displayed in File Explorer for Office 365 subscriptions on Creators' Update, and various advertising notifications displayed by default which promote Microsoft Edge when it is not set as the default web browser (including, in a September 2018 build, nag pop-ups displayed to interrupt the installation process of competitors). Market share and sales Up to August 2016, Windows 10 usage was increasing, with it then plateauing, while eventually in 2018, it became more popular than Windows 7 (though Windows 7 was still more used in some countries in Asia and Africa in 2019). , the operating system is running on over a billion devices, reaching the goal set by Microsoft two years after the initial deadline. Twenty-four hours after it was released, Microsoft announced that over 14million devices were running Windows10. On August 26, Microsoft said over 75million devices were running Windows10, in 192countries, and on over 90,000 unique PC or tablet models. According to Terry Myerson, there were over 110million devices running Windows10 as of October 6, 2015. On January 4, 2016, Microsoft reported that Windows10 had been activated on over 200million devices since the operating system's launch in July 2015. According to StatCounter, Windows 10 overtook Windows 8.1 in December 2015. Iceland was the first country where Windows 10 was ranked first (not only on the desktop, but across all platforms), with several larger European countries following. For one week in late November 2016, Windows 10 overtook first rank from Windows 7 in the United States, before losing it again. By February 2017, Windows 10 was losing market share to Windows 7. In mid-January 2018, Windows 10 had a slightly higher global market share than Windows 7, with it noticeably more popular on weekends, while popularity varies widely by region, e.g. Windows 10 was then still behind in Africa and far ahead in some other regions e.g. Oceania. Update system changes Windows 10 Home is permanently set to download all updates automatically, including cumulative updates, security patches, and drivers, and users cannot individually select updates to install or not. Microsoft offers a diagnostic tool that can be used to hide updates and prevent them from being reinstalled, but only after they had been already installed, then uninstalled without rebooting the system. Tom Warren of The Verge felt that, given web browsers such as Google Chrome had already adopted such an automatic update system, such a requirement would help to keep all Windows10 devices secure, and felt that "if you're used to family members calling you for technical support because they've failed to upgrade to the latest Windows service pack or some malware disabled Windows Update then those days will hopefully be over." Concerns were raised that because of these changes, users would be unable to skip the automatic installation of updates that are faulty or cause issues with certain system configurations—although build upgrades will also be subject to public beta testing via Windows Insider program. There were also concerns that the forced installation of driver updates through Windows Update, where they were previously designated as "optional", could cause conflicts with drivers that were installed independently of Windows Update. An example of such a situation occurred prior to the general release of the operating system, when an Nvidia graphics card driver that was automatically pushed to Windows10 users via Windows Update caused issues that prevented the use of certain functions, or prevented their system from booting at all. Criticism was also directed towards Microsoft's decision to no longer provide specific details on the contents of cumulative updates for Windows 10. On February 9, 2016, Microsoft retracted this decision and began to provide release notes for cumulative updates on the Windows website. Some users reported that during the installation of the November upgrade, some applications (particularly utility programs such as CPU-Z and Speccy) were automatically uninstalled during the upgrade process, and some default programs were reset to Microsoft-specified defaults (such as Photos app, and Microsoft Edge for PDF viewing), both without warning. Further issues were discovered upon the launch of the Anniversary Update ("Redstone"), including a bug that caused some devices to freeze (but addressed by cumulative update KB3176938, released on August 31, 2016), and that fundamental changes to how Windows handles webcams had caused many to stop working. In June 2017, a Redstone 3 Insider build (RS_EDGE_CASE in PC and rs_IoT on Mobile) was accidentally released to both Insider and non-Insider users on all Windows 10 devices, but the update was retracted, with Microsoft apologizing and releasing a note on their Windows Insider Program blog describing how to prevent the build from being installed on their device. According to Dona Sarkar, this was due to "an inadvertent deployment to the engineering system that controls which builds/which rings to push out to insiders." A Gartner analyst felt that Windows 10 Pro was becoming increasingly inappropriate for use in enterprise environments because of support policy changes by Microsoft, including consumer-oriented upgrade lifecycle length, and only offering extended support for individual builds to Enterprise and Education editions of Windows 10. Critics have acknowledged that Microsoft's update and testing practices had been affecting the overall quality of Windows 10. In particular, it was pointed out that Microsoft's internal testing departments had been prominently affected by a major round of layoffs undertaken by the company in 2014. Microsoft relies primarily on user testing and bug reports via the Windows Insider program (which may not always be of sufficient quality to identify a bug), as well as correspondence with OEMs and other stakeholders. In the wake of the known folder redirection data loss bug in the version 1809, it was pointed out that bug reports describing the issue had been present on the Feedback Hub app for several months prior to the public release. Following the incident, Microsoft updated Feedback Hub so that users may specify the severity of a particular bug report. When announcing the resumption of 1809's rollout, Microsoft stated that it planned to be more transparent in its handling of update quality in the future, through a series of blog posts that will detail its testing process and the planned development of a "dashboard" that will indicate the rollout progress of future updates. Distribution practices Microsoft was criticized for the tactics that it used to promote its free upgrade campaign for Windows 10, including adware-like behaviors, using deceptive user interfaces to coax users into installing the operating system, downloading installation files without user consent, and making it difficult for users to suppress the advertising and notifications if they did not wish to upgrade to 10. The upgrade offer was marketed and initiated using the "Get Windows 10" (GWX) application, which was first downloaded and installed via Windows Update in March 2015. Registry keys and group policies could be used to partially disable the GWX mechanism, but the installation of patches to the GWX software via Windows Update could reset these keys back to defaults, and thus reactivate the software. Third-party programs were also created to assist users in applying measures to disable GWX. In September 2015, it was reported that Microsoft was triggering automatic downloads of Windows 10 installation files on all compatible Windows 7 or 8.1 systems configured to automatically download and install updates, regardless of whether or not they had specifically requested the upgrade. Microsoft officially confirmed the change, claiming it was "an industry practice that reduces the time for installation and ensures device readiness." This move was criticized by users with data caps or devices with low storage capacity, as resources were consumed by the automatic downloads of up to 6 GB of data. Other critics argued that Microsoft should not have triggered any downloading of Windows 10 installation files without user consent. In October 2015, Windows 10 began to appear as an "Optional" update on the Windows Update interface, but pre-selected for installation on some systems. A Microsoft spokesperson said that this was a mistake, and that the download would no longer be pre-selected by default. However, on October 29, 2015, Microsoft announced that it planned to classify Windows 10 as a "recommended" update in the Windows Update interface sometime in 2016, which would cause an automatic download of installation files and a one-time prompt with a choice to install to appear. In December 2015, it was reported that a new advertising dialog had begun to appear, only containing "Upgrade now" and "Upgrade tonight" buttons, and no obvious method to decline installation besides the close button. In March 2016, some users also alleged that their Windows 7 and 8.1 devices had automatically begun upgrading to Windows 10 without their consent. In June 2016, the GWX dialog's behavior changed to make closing the window imply a consent to a scheduled upgrade. Despite this, an InfoWorld editor disputed the claims that upgrades had begun without any consent at all; testing showed that the upgrade to Windows 10 would only begin once the user accepts the end-user license agreement (EULA) presented by its installer, and that not doing so would eventually cause Windows Update to time out with an error, thus halting the installation attempt. It was concluded that these users may have unknowingly clicked the "Accept" prompt without full knowledge that this would begin the upgrade. In December 2016, Microsoft's chief marketing officer Chris Capossela admitted that the company had "gone too far" by using this tactic, stating, "we know we want people to be running Windows 10 from a security perspective, but finding the right balance where you're not stepping over the line of being too aggressive is something we tried and for a lot of the year I think we got it right." On January 21, 2016, Microsoft was sued in small claims court by a user whose computer had attempted to upgrade to Windows 10 without her consent shortly after the release of the operating system. The upgrade failed, and her computer was left in a broken state thereafter, which disrupted the ability to run her travel agency. The court ruled in favor of the user and awarded her $10,000 in damages, but Microsoft appealed. However, in May 2016, Microsoft dropped the appeal and chose to pay the damages. Shortly after the suit was reported on by the Seattle Times, Microsoft confirmed it was updating the GWX software once again to add more explicit options for opting out of a free Windows 10 upgrade; the final notification was a full-screen pop-up window notifying users of the impending end of the free upgrade offer, and contained "Remind me later", "Do not notify me again" and "Notify me three more times" as options. In March 2019, Microsoft announced that it would display notifications informing users on Windows 7 devices of the upcoming end of extended support for the platform, and direct users to a website urging them to upgrade to Windows 10 or purchase new hardware. This dialog will be similar to the previous Windows 10 upgrade prompts, but will not explicitly mention Windows 10. Privacy and data collection Privacy advocates and other critics have expressed concern regarding Windows10's privacy policies and its collection and use of customer data. Under the default "Express" settings, Windows10 is configured to send various information to Microsoft and other parties, including the collection of user contacts, calendar data, and "associated input data" to personalize "speech, typing, and inking input", typing and inking data to improve recognition, allowing apps to use a unique "advertisingID" for analytics and advertising personalization (functionality introduced by Windows 8.1) and allow apps to request the user's location data and send this data to Microsoft and "trusted partners" to improve location detection (Windows8 had similar settings, except that location data collection did not include "trusted partners"). Users can opt out from most of this data collection, but telemetry data for error reporting and usage is also sent to Microsoft, and this cannot be disabled on non-Enterprise editions of Windows10. Microsoft's privacy policy states, however, that "Basic"-level telemetry data is anonymized and cannot be used to identify an individual user or device. The use of Cortana also requires the collection of data "such as Your PC location, data from your calendar, the apps you use, data from your emails and text messages, who you call, your contacts and how often you interact with them on Your PC" to personalize its functionality. Rock Paper Shotgun writer Alec Meer argued that Microsoft's intent for this data collection lacked transparency, stating that "there is no world in which 45pages of policy documents and opt-out settings split across 13different settings screens and an external website constitutes 'real transparency'." Joel Hruska of ExtremeTech wrote that "the company that brought us the 'Scroogled' campaign now hoovers up your data in ways that would make Google jealous." However, it was also pointed out that the requirement for such vast usage of customer data had become a norm, citing the increased reliance on cloud computing and other forms of external processing, as well as similar data collection requirements for services on mobile devices such as Google Now and Siri. In August 2015, Russian politician Nikolai Levichev called for Windows10 to be banned from use within the Russian government, as it sends user data to servers in the United States. The Russian government had passed a federal law requiring all online services to store the data of Russian users on servers within the country by September 2016 or be blocked. Writing for ZDNet, Ed Bott said that the lack of complaints by businesses about privacy in Windows10 indicated "how utterly normal those privacy terms are in 2015." In a Computerworld editorial, Preston Gralla said that "the kind of information Windows10 gathers is no different from what other operating systems gather. But Microsoft is held to a different standard than other companies". The Microsoft Services agreement reads that the company's online services may automatically "download software updates or configuration changes, including those that prevent you from accessing the Services, playing counterfeit games, or using unauthorized hardware peripheral devices." Critics interpreted this statement as implying that Microsoft would scan for and delete unlicensed software installed on devices running Windows10. However, others pointed out that this agreement was specifically for Microsoft online services such as Microsoft account, Office 365, Skype, as well as Xbox Live, and that the offending passage most likely referred to digital rights management on Xbox consoles and first-party games, and not plans to police pirated video games installed on Windows10 PCs. Despite this, some torrent trackers announced plans to block Windows10 users, also arguing that the operating system could send information to anti-piracy groups that are affiliated with Microsoft. Writing about these allegations, Ed Bott of ZDNet compared Microsoft's privacy policy to Apple's and Google's and concluded that he "[didn't] see anything that looks remotely like Big Brother." Columnist Kim Komando argued that "Microsoft might in the future run scans and disable software or hardware it sees as a security threat," consistent with the Windows10 update policy. In September 2019, Microsoft hid the option to create a local account during a fresh installation if a PC is connected to the internet. This move was criticized by users who did not want to use an online Microsoft account. Additionally, in Windows 10 Home, the first Microsoft account linked to the primary user’s account can no longer be unlinked, but other users can unlink their own Microsoft accounts from their user accounts. In late-July 2020, Windows Defender began to classify modifications of the hosts file that block Microsoft telemetry servers as being a severe security risk. See also Comparison of operating systems History of operating systems List of operating systems Microsoft Windows version history References External links Windows 10 release information from Microsoft 2015 software ARM operating systems IA-32 operating systems Proprietary operating systems Tablet operating systems 10 X86-64 operating systems

Operating System (OS)

Ubuntu Ubuntu ( ) is a Linux distribution based on Debian and composed mostly of free and open-source software. Ubuntu is officially released in three editions: Desktop, Server, and Core for Internet of things devices and robots. All the editions can run on the computer alone, or in a virtual machine. Ubuntu is a popular operating system for cloud computing, with support for OpenStack. Ubuntu's default desktop has been GNOME since version 17.10. Ubuntu is released every six months, with long-term support (LTS) releases every two years. , the most recent long-term support release is 20.04 ("Focal Fossa"), which is supported until 2025 under public support and until 2030 as a paid option for companies and free for individuals who register. The latest standard release is 21.10 ("Impish Indri"), which is supported for nine months. Ubuntu is developed by British company Canonical, and a community of other developers, under a meritocratic governance model. Canonical provides security updates and support for each Ubuntu release, starting from the release date and until the release reaches its designated end-of-life (EOL) date. Canonical generates revenue through the sale of premium services related to Ubuntu and donations from those who download the Ubuntu software. Ubuntu is named after the Nguni philosophy of , which Canonical indicates means "humanity to others" with a connotation of "I am what I am because of who we all are". Background Ubuntu is built on Debian's architecture and infrastructure, and comprises Linux server, desktop and discontinued phone and tablet operating system versions. Ubuntu releases updated versions predictably every six months, and each release receives free support for nine months (eighteen months prior to 13.04) with security fixes, high-impact bug fixes and conservative, substantially beneficial low-risk bug fixes. The first release was in October 2004. Current long-term support (LTS) releases are supported for five years, and are released every two years. Since the release of Ubuntu 6.06, every fourth release receives long-term support. Long-term support includes updates for new hardware, security patches and updates to the 'Ubuntu stack' (cloud computing infrastructure). The first LTS releases were supported for three years on the desktop and five years on the server; since Ubuntu 12.04 LTS, desktop support for LTS releases was increased to five years as well. LTS releases get regular point releases with support for new hardware and integration of all the updates published in that series to date. Ubuntu packages are based on packages from Debian's unstable branch, which are synchronised every six months. Both distributions use Debian's deb package format and package management tools (e.g. APT and Ubuntu Software). Debian and Ubuntu packages are not necessarily binary compatible with each other, however, so packages may need to be rebuilt from source to be used in Ubuntu. Many Ubuntu developers are also maintainers of key packages within Debian. Ubuntu cooperates with Debian by pushing changes back to Debian, although there has been criticism that this does not happen often enough. Ian Murdock, the founder of Debian, had expressed concern about Ubuntu packages potentially diverging too far from Debian to remain compatible. Before release, packages are imported from Debian unstable continuously and merged with Ubuntu-specific modifications. One month before release, imports are frozen, and packagers then work to ensure that the frozen features interoperate well together. Ubuntu is currently funded by Canonical Ltd. On 8 July 2005, Mark Shuttleworth and Canonical announced the creation of the Ubuntu Foundation and provided initial funding of US$10 million. The purpose of the foundation is to ensure the support and development for all future versions of Ubuntu. Mark Shuttleworth describes the foundation goal as to ensure the continuity of the Ubuntu project. On 12 March 2009, Ubuntu announced developer support for third-party cloud management platforms, such as those used at Amazon EC2. 32-bit i386 processors were supported up to Ubuntu 18.04. It was decided to support "legacy software", i.e. select 32-bit i386 packages for Ubuntu 19.10 and 20.04 LTS. Features A default installation of Ubuntu contains a wide range of software that includes LibreOffice, Firefox, Thunderbird, Transmission, and several lightweight games such as Sudoku and Mines. Many additional software packages are accessible from the built in Ubuntu Software (previously Ubuntu Software Center) as well as any other APT-based package management tools. Many additional software packages that are no longer installed by default, such as Evolution, GIMP, Pidgin, and Synaptic, are still accessible in the repositories and installable by the main tool or by any other APT-based package management tool. Cross-distribution snap packages and flatpaks are also available, that both allow installing software, such as some of Microsoft's software, in most of the major Linux operating systems (such as any currently supported Ubuntu version and in Fedora). The default file manager is GNOME Files, formerly called Nautilus. All of the application software installed by default is free software. In addition, Ubuntu redistributes some hardware drivers that are available only in binary format, but such packages are clearly marked in the restricted component. Security Ubuntu aims to be secure by default. User programs run with low privileges and cannot corrupt the operating system or other users' files. For increased security, the sudo tool is used to assign temporary privileges for performing administrative tasks, which allows the root account to remain locked and helps prevent inexperienced users from inadvertently making catastrophic system changes or opening security holes. Polkit is also being widely implemented into the desktop. Most network ports are closed by default to prevent hacking. A built-in firewall allows end-users who install network servers to control access. A GUI (GUI for Uncomplicated Firewall) is available to configure it. Ubuntu compiles its packages using GCC features such as PIE and buffer overflow protection to harden its software. These extra features greatly increase security at the performance expense of 0.01% in 64-bit. Ubuntu also supports full disk encryption as well as encryption of the home and Private directories. Installation The system requirements vary among Ubuntu products. For the Ubuntu desktop release 20.04 LTS, a PC with at least 2 GHz dual-core processor, 4 GB of RAM and 25 GB of free disk space is recommended. For less powerful computers, there are other Ubuntu distributions such as Lubuntu and Xubuntu. Ubuntu also supports the ARM architecture. It is also available on Power ISA, while older PowerPC architecture was at one point unofficially supported, and now newer Power ISA CPUs (POWER8) are supported. The x86-64 ("AMD64") architecture is also officially supported. Live images are the typical way for users to assess and subsequently install Ubuntu. These can be downloaded as a disk image (.iso) and subsequently burnt to a DVD or USB flash drive and then booted. Other methods include running the live version via UNetbootin, or Startup Disk Creator (a pre-installed tool on Ubuntu, available on machines already running the OS) directly from a USB drive (making, respectively, a live DVD or live USB medium). Running Ubuntu in this way is slower than running it from a hard drive, but does not alter the computer unless specifically instructed by the user. If the user chooses to boot the live image rather than execute an installer at boot time, there is still the option to then use an installer called Ubiquity to install Ubuntu once booted into the live environment. Disk images of all current and past versions are available for download at the Ubuntu web site. Additionally, USB flash drive installations can be used to boot Ubuntu and Kubuntu in a way that allows permanent saving of user settings and portability of the USB-installed system between physical machines (however, the computers' BIOS must support booting from USB). In newer versions of Ubuntu, the Ubuntu Live USB creator can be used to install Ubuntu on a USB drive (with or without a live CD or DVD). Creating a bootable USB drive with persistence is as simple as dragging a slider to determine how much space to reserve for persistence; for this, Ubuntu employs casper. Package classification and support Ubuntu divides most software into four domains to reflect differences in licensing and the degree of support available. Some unsupported applications receive updates from community members, but not from Canonical Ltd. Free software includes software that has met the Ubuntu licensing requirements, which roughly correspond to the Debian Free Software Guidelines. Exceptions, however, include firmware, in the Main category, because although some firmware is not allowed to be modified, its distribution is still permitted. Non-free software is usually unsupported (Multiverse), but some exceptions (Restricted) are made for important non-free software. Supported non-free software includes device drivers that can be used to run Ubuntu on some current hardware, such as binary-only graphics card drivers. The level of support in the Restricted category is more limited than that of Main, because the developers may not have access to the source code. It is intended that Main and Restricted should contain all software needed for a complete desktop environment. Alternative programs for the same tasks and programs for specialized applications are placed in the Universe and Multiverse categories. In addition to the above, in which the software does not receive new features after an initial release, Ubuntu Backports is an officially recognized repository for backporting newer software from later versions of Ubuntu. The repository is not comprehensive; it consists primarily of user-requested packages, which are approved if they meet quality guidelines. Backports receives no support at all from Canonical, and is entirely community-maintained. The -updates repository provides stable release updates (SRU) of Ubuntu and are generally installed through update-manager. Each release is given its own -updates repository (e.g. intrepid-updates). The repository is supported by Canonical Ltd. for packages in main and restricted, and by the community for packages in universe and multiverse. All updates to the repository must meet certain requirements and go through the -proposed repository before being made available to the public. Updates are scheduled to be available until the end of life for the release. In addition to the -updates repository, the unstable -proposed repository contains uploads that must be confirmed before being copied into -updates. All updates must go through this process to ensure that the patch does truly fix the bug and there is no risk of regression. Updates in -proposed are confirmed by either Canonical or members of the community. Canonical's partner repository lets vendors of proprietary software deliver their products to Ubuntu users at no cost through the same familiar tools for installing and upgrading software. The software in the partner repository is officially supported with security and other important updates by its respective vendors. Canonical supports the packaging of the software for Ubuntu and provides guidance to vendors. The partner repository is disabled by default and can be enabled by the user. Some popular products distributed via the partner repository are Adobe Flash Player, Adobe Reader and Skype. The free software Wine compatibility layer can be installed to allow users to run Windows software. Package Archives A Personal Package Archive (PPA) is a software repository for uploading source packages to be built and published as an Advanced Packaging Tool (APT) repository by Launchpad. While the term is used exclusively within Ubuntu, Launchpad's host, Canonical, envisions adoption beyond the Ubuntu community. Third-party software Some third-party software that does not limit distribution is included in Ubuntu's multiverse component. The package ubuntu-restricted-extras additionally contains software that may be legally restricted, including support for MP3 and DVD playback, Microsoft TrueType core fonts, Sun's Java runtime environment, Adobe's Flash Player plugin, many common audio/video codecs, and unrar, an unarchiver for files compressed in the RAR file format. Additionally, third-party application suites are available for download via Ubuntu Software and the Snap store, including many games such as Braid, Minecraft and Oil Rush, software for DVD playback and media codecs. Releases Each Ubuntu release has a version number that consists of the year and month number of the release. For example, the first release was Ubuntu 4.10 as it was released on 20 October 2004. Ubuntu releases are also given alliterative code names, using an adjective and an animal (e.g. "Xenial Xerus"). With the exception of the first two releases, code names are in alphabetical order, allowing a quick determination of which release is newer, at least until restarting the cycle with the release of Artful Aardvark in October 2017. Commonly, Ubuntu releases are referred to using only the adjective portion of the code name; for example, the 18.04 LTS release is commonly known as "Bionic". Releases are timed to be approximately one month after GNOME releases. Upgrades from one LTS release to the next LTS release (e.g. Ubuntu 16.04 LTS to Ubuntu 18.04 LTS and then to Ubuntu 20.04 LTS) are supported, while upgrades from non-LTS have only supported upgrade to the next release, regardless of its LTS status (e.g. Ubuntu 15.10 to Ubuntu 16.04 LTS). However, it is possible to skip an LTS upgrade, going straight from 16.04 LTS to 18.04.5 LTS, by waiting for a point release that supports such updating. LTS releases have optional extended security maintenance (ESM) support available, including 14.04 "Trusty" that is otherwise out of public support, adding support for that version up to 2022, that was later extended to a total of 10 years (and for 16.04 LTS). Ubuntu 10.10 (Maverick Meerkat), was released on 10 October 2010 (10–10–10). This departed from the traditional schedule of releasing at the end of October in order to get "the perfect 10", and makes a playful reference to The Hitchhiker's Guide to the Galaxy books, since, in binary, 101010 equals decimal 42, the "Answer to the Ultimate Question of Life, the Universe and Everything" within the series. Ubuntu (16.04.5 and later) requires a 2 GB or larger installation medium. However, there is an option to install it with a Minimal CD. Variants Ubuntu Desktop (formally named as Ubuntu Desktop Edition, and simply called Ubuntu) is the variant officially recommended for most users. It is designed for desktop and laptop PCs and officially supported by Canonical. A number of variants are distinguished simply by each featuring a different desktop environment. LXQt and Xfce are often recommended for use with older PCs that may have less memory and processing power available. Official distributions Most Ubuntu editions and flavours simply install a different set of default packages compared to the standard Ubuntu Desktop. Since they share the same package repositories, all of the same software is available for each of them. Ubuntu Core is the sole exception as it only has access to packages in the Snap Store. Ubuntu had some official distributions that have been discontinued, such as Edubuntu; including some previously supported by Canonical, like Ubuntu Touch, that is now maintained by volunteers (UBports Community). Unofficial distributions Alongside the official flavours are those that are unofficial. These are still in the process of becoming recognized as official flavours by Canonical. Cloud computing Ubuntu offers Ubuntu Cloud Images which are pre-installed disk images that have been customized by Ubuntu engineering to run on cloud-platforms such as Amazon EC2, OpenStack, Microsoft Azure and LXC. Ubuntu is also prevalent on VPS platforms such as DigitalOcean. Ubuntu has support for OpenStack, with Eucalyptus to OpenStack migration tools added by Canonical. Ubuntu 11.10 added focus on OpenStack as the Ubuntu's preferred IaaS offering though Eucalyptus is also supported. Another major focus is Canonical Juju for provisioning, deploying, hosting, managing, and orchestrating enterprise data center infrastructure services, by, with, and for the Ubuntu Server. Adoption and reception Installed base As Ubuntu is distributed freely and historically there was no registration process (still optional), Ubuntu usage can only be roughly estimated. In 2015, Canonical's Ubuntu Insights page stated "Ubuntu now has over 40 million desktop users and counting". W3Techs Web Technology Surveys estimated in November 2020 that: Ubuntu is by far the most popular Linux distribution for running web servers; of the websites they analyze it's "used by 47.3% of all the websites who use Linux", and Ubuntu alone powers more websites than Microsoft Windows, which powers 28.2% of all websites, or 39% of the share Unix has (which includes Linux and thus Ubuntu). All Linux/Unix distributions in total power well over twice the number of hosts as Windows for websites based on W3Techs numbers. Ubuntu and Debian only (which Ubuntu is based on, with the same package manager and thus administered the same way) make up 65% of all Linux distributions for web serving use; the usage of Ubuntu surpassed Debian (for such server use) in May 2016. Ubuntu is the most popular Linux distribution among the top 1000 sites and gains around 500 of the top 10 million websites per day. W3Techs analyses the top 10 million websites only. Wikimedia Foundation data (based on user agent) for September 2013 shows that Ubuntu generated the most page requests to Wikimedia sites, including Wikipedia, among recognizable Linux distributions. , Ubuntu 20.04.1 LTS is used in a supercomputer on the TOP500 list, currently the fifth fastest one in the world after an upgrade from 7th place, where it entered the list in June. Another Nvidia supercomputer tops the Green500 list (and it and the next one are also Ubuntu-based), a list which is a reordering of former list, ordered by power-efficiency. On the TOP500 list, that supercomputer is ranked 172nd. Large-scale deployments The public sector has also adopted Ubuntu. , the Ministry of Education and Science of the Republic of Macedonia deployed more than 180,000 Ubuntu-based classroom desktops, and has encouraged every student in the country to use Ubuntu-powered computer workstations; the Spanish school system has 195,000 Ubuntu desktops. The French police, having already started using open-source software in 2005 by replacing Microsoft Office with OpenOffice.org, decided to transition to Ubuntu from Windows XP after the release of Windows Vista in 2006. By March 2009, the Gendarmerie Nationale had already switched 5000 workstations to Ubuntu. Based on the success of that transition, it planned to switch 15,000 more over by the end of 2009 and to have switched all 90,000 workstations over by 2015 (GendBuntu project). Lt. Colonel Guimard announced that the move was very easy and allowed for a 70% saving on the IT budget without having to reduce its capabilities. In 2011, Ubuntu 10.04 was adopted by the Indian justice system. The Government of Kerala adopted Ubuntu for the legislators in Kerala and the government schools of Kerala began to use customized IT@School Project Ubuntu 10.04 which contains specially created software for students. Previously, Windows was used in the schools. Textbooks were also remade with an Ubuntu syllabus and was used in schools as of 2011. The city of Munich, Germany, forked Kubuntu 10.04 LTS and created LiMux for use on the city's computers. After originally planning to migrate 12,000 desktop computers to LiMux, it was announced in December 2013 that the project had completed successfully with the migration of 14,800 out of 15,500 desktop computers, but still keeping about 5000 Windows clients for unported applications. In February 2017 the majority coalition decided, against heavy protest from the opposition, to evaluate the migration back to Windows, after Microsoft had decided to move its company headquarters to Munich. Governing Mayor Dieter Reiter cited lack of compatibility with systems outside of the administrative sector, such as requiring a governmental mail server to send e-mails to his personal smartphone, as reasons for the return, but has been criticised for evaluating administrative IT based on private and business standards. In March 2012, the government of Iceland launched a project to get all public institutions using free and open-source software. Already, several government agencies and schools have adopted Ubuntu. The government cited cost savings as a big factor for the decision, and also stated that open-source software avoids vendor lock-in. A 12-month project was launched to migrate the biggest public institutions in Iceland to using open-source software, and help ease the migration for others. US president Barack Obama's successful campaign for re-election in 2012 used Ubuntu in its IT department. In August 2014, the city of Turin, Italy, announced its migration from Windows XP to Ubuntu for the 8,300 desktop computers used by the municipality, becoming the first city in Italy to adopt Ubuntu. Starting in 2008, the Wikimedia Foundation, the non-profit organization behind Wikipedia, switched from multiple different Linux operating systems to Ubuntu. Reception Ubuntu was awarded the Reader Award for best Linux distribution at the 2005 LinuxWorld Conference and Expo in London, received favorable reviews in online and print publications, and has won InfoWorld's 2007 Bossie Award for Best Open Source Client OS. In early 2008, PC World named Ubuntu the "best all-around Linux distribution available today", though it criticized the lack of an integrated desktop effects manager. Chris DiBona, the program manager for open-source software at Google, said "I think Ubuntu has captured people's imaginations around the Linux desktop," and "If there is a hope for the Linux desktop, it would be them". , almost half of Google's 20,000 employees used Goobuntu, a slightly modified version of Ubuntu. In 2012, ZDNet reported that Ubuntu was still Google's desktop of choice. In March 2016, Matt Hartley picked a list of best Linux distributions for Datamation; he chose Ubuntu as number one. In 2008, Jamie Hyneman, co-host of the American television series MythBusters, advocated Linux (giving the example of Ubuntu) as a solution to software bloat. Other celebrity users of Ubuntu include science fiction writer Cory Doctorow and actor Stephen Fry. In January 2014, the UK's authority for computer security, CESG, reported that Ubuntu 12.04 LTS was "the only operating system that passes as many as 9 out of 12 requirements without any significant risks", though it was unclear if any other Linux distributions were tested. 32-bit "deprecation" controversy In June 2019, Canonical announced that they would be deprecating support for 32-bit applications and libraries in Ubuntu 19.10. Because Steam's Linux client depends on these 32-bit libraries, Valve announced that they would no longer be supporting Ubuntu. After uproar from the Linux gaming community, Canonical backtracked on this decision and decided to support select 32-bit libraries. As a result, Valve will support Ubuntu 19.10 again. Wine needs most of the same 32-bit library packages that the Steam package depends on, and more, to enable its version of WoW64 to run 32-bit Windows applications. The parts of Wine that would continue to function without 32-bit libraries would be limited to the subset of Windows applications that have a 64-bit version, removing decades of Windows compatibility. In Canonical's statement on bringing back the libraries, they mentioned using "container technology" in the future to make sure that Wine continues to function. Conformity with European data privacy law Soon after being introduced, doubts emerged on the conformance of the shopping lens with the European Data Protection Directive. A petition was later signed and delivered to Canonical demanding various modifications to the feature in order to clearly frame it within European law. Canonical did not reply. In 2013, a formal complaint on the shopping lens was filed with the Information Commissioner's Office (ICO), the UK data privacy office. Almost one year later the ICO ruled in favour of Canonical, considering the various improvements introduced to the feature in the meantime to render it conformable with the Data Protection Directive. According to European rules, this ruling is automatically effective in the entirety of the European Union. However, the ruling also made clear that at the time of introduction the feature was not legal, among other things, since it was missing a privacy policy statement. Local communities (LoCos) In an effort to reach out to users who are less technical, and to foster a sense of community around the distribution, Local Communities, better known as "LoCos", have been established throughout the world. Originally, each country had one LoCo Team. However, in some areas, most notably the United States and Canada, each state or province may establish a team. A LoCo Council approves teams based upon their efforts to aid in either the development or the promotion of Ubuntu. Hardware vendor support Ubuntu works closely with OEMs to jointly make Ubuntu available on a wide range of devices. A number of vendors offer computers with Ubuntu pre-installed, including Dell, Hasee, Sharp Corporation, and Cirrus7. Specifically, Dell offers the XPS 13 laptop, Developer Edition with Ubuntu pre-installed. Together, Dell, Lenovo, HP, and Acer offer over 200 desktop and over 400 laptop PCs preloaded with Ubuntu. System76 computers are also sold with Ubuntu. Dell and System76 customers are able to choose between 30-day, three-month, and yearly Ubuntu support plans through Canonical. Dell computers (running Ubuntu 10.04) include extra support for ATI/AMD Video Graphics, Dell Wireless, Fingerprint Readers, HDMI, Bluetooth, DVD playback (using LinDVD), and MP3/WMA/WMV. Asus is also selling some Eee PCs with Ubuntu pre-installed and announced "many more" models running Ubuntu for 2011. Vodafone has made available a notebook for the South-African market called "Webbook". Dell sells computers (initially Inspiron 14R and 15R laptops) pre-loaded with Ubuntu in India and China, with 850 and 350 retail outlets respectively. Starting in 2013, Alienware began offering its X51 model gaming desktop pre-installed with Ubuntu at a lower price than if it were pre-installed with Windows. While Linux already works on IBM's mainframe system (Linux on IBM Z), IBM in collaboration with Canonical (and SUSE; "Linux Foundation will form a new Open Mainframe Project") announced Ubuntu support for their z/Architecture for the first time (IBM claimed their system, IBM zEnterprise System, version z13, the most powerful computer in the world in 2015; it was then the largest computer by transistor count; again claimed fastest in 2017 with IBM z14), at the time of their "biggest code drop" ("LinuxOne") in Linux history. In early 2015, Intel launched the Intel Compute Stick small form factor computer available preloaded with Ubuntu or Windows operating systems. Windows interoperability In March 2016, Microsoft announced that it would support the Ubuntu userland on top of the Windows 10 kernel by implementing the Linux system calls as a subsystem. At the time, it was focused on command-line tools like Bash and was aimed at software developers. WSL was made available with Windows 10, version 1709. As of 2019, other Linux distributions are also supported. In 2019, Microsoft announced the new WSL 2 subsystem that includes a Linux kernel, that Canonical announced will have "full support for Ubuntu". By this time, it was possible to run graphical Linux apps on Windows. In 2021, Microsoft went on to add out-of-the-box support for graphical Linux apps, through the project. In May 2021, Microsoft extended its Threat and Vulnerability Management solution, which was a Windows-only solution thus far, to support Ubuntu, RHEL, and CentOS. Besides, starting with version 6, PowerShell runs on Ubuntu and can manage both Windows and Ubuntu computers remotely from either platforms. See also Comparison of Linux distributions Notes References External links 2004 software ARM Linux distributions Debian-based distributions Enterprise Linux distributions Free software operating systems Operating system distributions bootable from read-only media Power ISA Linux distributions PowerPC Linux distributions PowerPC operating systems x86-64 Linux distributions ARM operating systems Linux distributions

Operating System (OS)

Rodos (operating system) Rodos (Realtime Onboard Dependable Operating System) is a real-time operating system for embedded systems and was designed for application domains demanding high dependability. History Rodos was developed at the German Aerospace Center and has its roots in the operating system BOSS. It is used for the current micro satellite program of the German Aerospace Center. The system runs on the operational satellite TET-1 and will be used for the currently developed satellite BiROS. Rodos is further enhanced and extended at the German Aerospace Center as well as the department for aerospace information technology at the University of Würzburg. Features An important aspect of Rodos is its integrated real time middleware. Developing the control and payload software on the top of a middleware provides the maximum of modularity today. Applications/modules can be developed independently and it is very simple to interchange modules later without worrying about side effects, because all modules are encapsulated as Building Blocks (BB) and can be accessed and they can access other resources only by well defined interfaces. Rodos was implemented as a software framework in C++ with an object oriented application interface (API). it is organized in layers: The lowest layer (1) is responsible for control of the embedded system hardware (HAL: Hardware abstraction layer). The next layer (2) kernel: administrates the local resources, threads and time. On top of the kernel we have the middleware (layer 3) which enables communication between BBs using a publisher subscriber multicast protocol. And on the top of the middleware the user may implement his applications (layer 4) as a distributed software network of simple BBs. The Building Blocks API on the top of the middleware is a service oriented interface. BBs interact by providing services to other BBs and using services from other BBs. As mentioned before, the original purpose of Rodos was to control satellites. It was designed as the brain of the Avionic system and introduces for the first time (2001) the NetworkCentric concept. A networkCentric core avionics machine consists of several harmonized components which work together to implement dependable computing in a simple way. In an NetworkCentric system we have a software network of BBs and a hardware Network interconnecting vehicles (radio communication), computers inside of vehicles (buses and point to point links), intelligent devices (attached to buses) and simple devices attached to front end computers. To communicate with (node) external units, including devices and other computing units, each node provides a gateway to the network and around the network's several devices (IO Devs and computing nodes) may be attached to the system. The messages exchange provided by the middleware and gateways is asynchronous, using the publisher-subscriber protocol. No fixed communication paths are established and the system can be reconfigured easily at run-time. For instance, several replicas of the same software can run in different nodes and publish the result using the same topic, without knowing each other. A voter may subscribe to that topic and vote on the correct result. Application can migrate from node to node or even to other vehicles without having to reconfigure the communication system. The core of the middleware distributes messages only locally, but using the integrated gateways to the NetworkCentric network, messages can reach any node and application in the network. The communication in the whole system includes software applications, computing nodes and even IO devices. Publishers make messages public under a given topic. Subscribers (zero, one or more) to a given topic get all messages which are published under this topic. As mentioned before, for this communication there is no difference in which node (computing unit or device) the publisher and subscribers are running and beyond this, they may be any combination of software tasks and hardware devices! To establish a transfer path, both the publisher and the subscriber must share the same topic. A Topic is a pair consisting of a data-type and an integer representing a topic identifier. Both the software middleware and the hardware network switch (called middleware switch), interpret the same publisher/subscriber protocol. Rodos enables the user to write realtime applications for different architectures in an easy, efficient way. During the development special attention was paid to implement the various features of Rodos in a simple, nevertheless robust way. Unnecessary complexity was avoided to provide the user with a straightforward, clearly arranged system. Rodos supports typical features of realtime operatingsystems, like threads and semaphores. Among other features Rodos offers: object-oriented C++ interfaces, ultra fast booting real time priority controlled preemptive multithreading, time management (as a central point), thread safe communication and synchronisation, event propagation Examples Hello World The common Hello world example program looks like this in Rodos. #include "rodos.h" class HelloWorld : public StaticThread<> { void run(){ PRINTF("Hello World!\n"); } } helloworld; The class Thread is extended by a custom run() procedure, which writes Hello World to the standard output with PRINTF. All Rodos components needed for application development are accessible via the rodos.h header file. Threads Rodos uses fair priority controlled preemptive scheduling. The thread with the highest priority is executed while running threads with a lower priority are paused (preemptive multitasking). If there are more than one threads with the same priority, each of them gets a fixed share of computing time and they are executed in turns. Example: #include <rodos.h> class HighPriorityThread: public StaticThread<> { public: HighPriorityThread() : StaticThread("HiPriority", 25) { } void run() { while (1) { PRINTF("*"); suspendCallerUntil(NOW() + 1*SECONDS); } } } highprio; class LowPriorityThread: public StaticThread<> { public: LowPriorityThread() : StaticThread("LowPriority", 10) { } void run() { while (1) { PRINTF("."); } } } lowprio; The thread LowPriorityThread constantly writes the character "." and is interrupted every second by the thread HighPriorityThread, which writes the character "*". Topics Rodos uses so-called Topics to enable communication between threads and over gateways between different systems. A Topic represents a message of a certain kind. A thread can publish Topics as well as subscribe to a Topic to receive all messages that belong to a type of message. The message system conforms to the publish–subscribe pattern. Here is a simple example with one publisher and one subscriber, which both use the Topic counter1 containing only one integer value. Example: #include <rodos.h> Topic<long> counter1(-1, "counter1"); class MyPublisher : public StaticThread<> { public: MyPublisher() : StaticThread("SenderSimple") { } void run() { long cnt = 0; TIME_LOOP(3*SECONDS, 3*SECONDS) { PRINTF("Publish: %ld\n", ++cnt); counter1.publish(cnt); } } } publisher; class MySubscriber : public SubscriberReceiver<long> { public: MySubscriber() : SubscriberReceiver<long>(counter1) { } void put(long &data) { PRINTF("Received: %ld\n", data); } }subscriber; The Publisher-Thread post every three seconds an ascending counter value, while the Subscriber-Thread simply displays the received integer value. Supported architectures Supported instruction set architectures: ARM7 (e.g. ARM Cortex-M3, Raspberry Pi's SoC) Atmel AVR32 STM32 32-bit PowerPC (PowerPC 405) Furthermore, Rodos can run as a guest on a different host operating system. Linux FreeRTOS RTEMS Windows TinyOS POSIX-Compatible operating systems References External links University of Wuerzburg - The Rodos Framework Embedded operating systems ARM operating systems

Operating System (OS)

Panos (operating system) PANOS is a discontinued computer operating system developed by Acorn Computers in the 1980s and released in 1985, which ran on the 32016 Second Processor for the BBC Micro and the Acorn Cambridge Workstation. These systems had essentially the same architecture, based on a 32-bit NS32016 CPU; the ACW having a BBC Micro-based "I/O processor". Access to the I/O processor was through a NS32016 firmware kernel called Pandora. Panos ran on the NS32016 and was a rudimentary single-user operating system, written in Modula-2. It provided a simple command line interpreter, a text editor and access to DFS, ADFS or NFS file systems via the I/O processor. Targeted at the academic and scientific user community, it came bundled with compilers for the FORTRAN 77, C, Pascal and LISP programming languages. Commands The following list of commands is supported by the Panos command line interpreter. .space .Delete .Help .key .NewCommand .Obey .pwd .Quit .Run .Set .swd .wait Access Catalogue Configure Copy Create Delete Echo Logon Rename Set Show Star References Notes Acorn Computers Acorn operating systems Discontinued operating systems

Operating System (OS)

PSOS (real-time operating system) rtos (Portable Software On Silicon) is a real-time operating system (RTOS), created in about 1982 by Alfred Chao, and developed and marketed for the first part of its life by his company Software Components Group (SCG). In the 1980s, rtos rapidly became the RTOS of choice for all embedded systems based on the Motorola 68000 series family architecture, because it was written in 68000 assembly language and was highly optimised from the start. It was also modularised, with early support for OS-aware debugging, plug-in device drivers, Internet protocol suite (TCP/IP) stacks, language libraries, and disk subsystems. Later came source code level debugging, multiprocessing support, and further computer networking extensions. In about 1991, Software Components Group was acquired by Integrated Systems Inc. (ISI) which further developed pSOS, then renamed as pSOS+, for other microprocessor families, by rewriting most of it in the programming language C. Attention was also paid to supporting successively more integrated development environments, culminating in pRISM+. In July 1994, Integrated Systems acquired Digital Research's modular real-time multi-tasking operating system FlexOS from Novell. In 1995, Integrated Systems offered a pSOSystem/NEST package for Novell's Embedded Systems Technology (NEST). In February 2000, Integrated Systems, Inc. was acquired by Wind River Systems, the originators of rival RTOS VxWorks. Despite initial reports that pSOS support would continue, development was halted. Wind River announced plans for a 'convergence' version of VxWorks which will support pSOS system calls, and that no further releases of pSOS will occur. NXP Semiconductors acquired pSOS for TriMedia from Wind River and continued to support this OS for the TriMedia VLIW core. Migration away from pSOS In March 2000, rival company Express Logic released their Evaluation Kit for pSOS+ users, designed to provide a migration path to its ThreadX RTOS. During August 2000, MapuSoft Technologies Inc. came up with the pSOS OS Changer porting kit which can smoothly move the software to multiple OS such as Linux, VxWorks, and more. It includes an integrated development environment (IDE) and application programming interface (API) optimization along with a profiling tool to measure API timing on target boards (www.mapusoft.com). In August 2007, RoweBots, a former partner of SCG and ISI, open sourced their pSOS+ compatible version called Reliant. It is available to all that wish to upgrade without applications changes. The Xenomai project supports pSOS+ APIs (and others traditional RTOS APIs) over a Linux-based real-time framework to allow existing industrial applications to migrate easily to a Linux-based environment while keeping stringent real-time guarantees. Another open sourced alternative is RTEMS, which has support for various APIs, including the "Classic API" (compatible to pSOS) and the POSIX API. Compared to Linux, RTEMS is a closer match to pSOS applications due to its lower memory footprint and its strict realtime behaviour. Popular SSL/TLS libraries such as wolfSSL still support pSOS. See also FlexOS Novell Embedded Systems Technology (NEST) MapuSoft Technologies Inc. UNIX System V STREAMS References Further reading Real-time operating systems 1982 software

Operating System (OS)

OS-tan OS-tan is an Internet meme consisting of moe anthropomorphs of popular operating systems, originating on the Japanese imageboard Futaba Channel. The designs of OS-tan, which were created by heterogeneous amateur Japanese artists, are typically female; for example, the personifications of Microsoft Windows operating systems are often depicted as sisters of varying ages. The -tan element in the term is a hypocoristic suffix in Japanese. Though initially appearing only in fan works, the OS-tan proved popular enough that Microsoft branches in Singapore and Taiwan used the OS-tan concept as the basis for ad campaigns for Internet Explorer and Microsoft Silverlight, respectively. History The concept of the OS-tan is reported to have begun as a personification of the common perception of Windows Me (Released in 2000 by Microsoft as the 9x counterpart to Windows 2000) as unstable and prone to frequent crashes. Discussions on Futaba Channel likened this to the stereotype of a fickle, troublesome girl and as this personification expanded Me-tan was created and followed by the other characters. One of the early works to predominantly feature the OS-tan was an interactive Flash animation showing a possible intro to an imaginary anime show known as Trouble Windows. A fansub of this was eventually created and is partly responsible for the spread of the OS-tan to English language imageboards. The OS-tan is not an original concept and was pre-dated by Toy's iMac Girl, who was featured on a series of desktops released between August 1998 and March 1999. Commercial products Ohzora Publishing produced one book based on OS-tan characters, titled . It includes illustrations by over 25 contributors. It also includes 95-tan, ME-tan, XP-tan figures, titled OS Girl 95, OS Girl me, OS Girl XP respectively, but include a molded space for 2k-tan (named OS Girl 2K). ME-tan, 2K-tan, XP-tan were designed by GUHICO of Stranger Workshop, while 95-tan was designed by Fujisaki Shiro from H.B.Company. Parthenon Production Limited, company had commercialized Pink Company's OS-tan products. MALINO from Deja Vu ArtWorks produced the Me Document and Shared Folder! trilogy, which were sold in digital format. Japanese version of Windows 7 Ultimate DSP Edition includes the unofficial Nanami Madobe mascot. This inspired Microsoft Taiwan to launch an official mascot for Microsoft Silverlight, Hikaru. This was followed up by giving Hikaru "sisters", Lei, Aoi, and Yu. A special package of the Japanese Windows 7 Ultimate DSP Edition, called the Touch Mouse Artist Edition or Touch Mouse Limited Edition Artist Series, came with an animated tutorial Windows theme (with custom sounds and three desktop backgrounds) featuring Madobe Nanami. In 2009, an Ubuntu-based comic titled Ubunchu! was serialized in Kantan Ubuntu!, a spinoff from Weekly ASCII magazine. It was authored by Hiroshi Seo, with English version translated by Fumihito Yoshida, Hajime Mizuno, Martin Owens, Arturo Silva, and Anton Ekblad. Tan suffix The Japanese suffix is a mispronunciation of , an informal, intimate, and diminutive honorific suffix for a person, used for friends, family, and pets. In this case, the mispronunciation is used intentionally to achieve the contrived cute or charming effect that is commonly associated with its use by young children and is also sometimes added to the names of non-mascot characters. The personifications as a whole are commonly simply called mascots or mascot characters, and as such the -tan suffix itself means nothing outside its role as an honorific and its implications of cuteness. Normal suffixes, including -san, -chan, and -kun are also used in the name of some OS-tan, depending on the character and the speaker's preference; or the suffix may be omitted entirely. New Generation OS-tans While there are mascots of Windows versions from 7 to 10, currently there is no mascot for Windows 11 as of yet. Windows 10 The name of the Windows 10 mascot was officially introduced as Tōko (or Touko) Madobe on 31 July 2015. As confirmed on the character's official Facebook page, her name is a homonym for one of the readings for the Japanese word for 'ten': . Her name was chosen by fans through an online poll. According to her fictional profile, her origins are the Madobe family and she is set 100 years in the future. She likes online gaming and supporting others. Her personal traits are being an excellent student, and expanding her knowledge on technology. Her manager often worries since she’s a bit spontaneous. She also enjoys cheering on people who are working hard and doing their best. She has a part-time job at the Akibano Custom Computer Company where she is a rookie. This level of back story is rather unusual for OS-tan. Windows 8.1 The Japanese Windows 8.1 Pro DSP edition Madobe Family version by Windows Navi+ (Techno-Alliance Corp.) is a limited (1000 units) version of Windows 8.1 Pro 32/64-bit edition with three types of Madobe family picture password wallpapers, Madobe character voices (Nanami, Yū, Ai, Claudia), Madobe family complete edition Windows theme pack, previously unpublished Madobe family designs, Final Pasocom Data Hikkoshi 9+ licence key, Skype three-month free trial, historical Windows logo stickers (XP, Vista, 7, 8). Other editions include a Memorial Pack version without voice, theme pack, stickers (6191 units); a 64-bit Windows Memorial Pack version with a Sculpt Mobile Mouse with Nanami decor (810 units). These editions were available for preorder on 2013-10-04 with release date on 2013-10-18. As part of the market launch, a Facebook draw of 8 followers took place when follower count reaches 80001; and total Twitter follower count for Yū and Ai reach 8001, where winners receive Yū- and Ai-themed prizes. Additional types of Windows 8.1 Pro DSP edition Madobe family theme packs were also sold by Ark (TowerHill), ZOA Corporation, Tsukumo (Project White), Dospara, Buy More (Unit.com), Big Camera (Sofmap), and PC One. These versions include two types of wallpapers (Christmas, New Year), theme pack with system voices. Windows 8 The Japanese Windows 8 Pro DSP editions were released in Madobe Yū (or Yuu, ) and Madobe Ai () editions by Windows Navi+ (Techno-Alliance Corp.). Both versions (4,000 units per character, thus 8,000 total) include a Microsoft Wedge touch mouse with the Windows 8 logo, character-specific Windows theme (three theme pack wallpapers, event sounds in the respective character's voice), picture password images. In addition, Limited Akihabara Editions (444 units per character, 888 total), sold in Tokyo's Akihabara shopping district, include Madobe Ai/Yū edition of Microsoft Wedge Touch Mouse, an alternate character-specific event sound samples and theme pack and an alternate wallpaper for its respective character. Nipponbashi versions (500 units per character), sold in Nipponbashi in Osaka, include Microsoft Wedge touch mouse (with Ai and Yū decal), three theme pack wall papers (two common and one character-specific), and Yū or Ai event sounds. The Nipponbashi packages include different art. The 32/64-bit version availability depends on retailer. Asuka Nishi voices the short-haired Yū, while Nao Tamura voices the long-haired Ai. The Windows 8 Can Edition from Unitcom (available for the first 2,888 copies) included notepad, T-shirt, two-way mouse pad, pocket media case, smart phone stand cleaning, two-way PC cleaner, Yū and Ai badges, and a freeze blanket. The extended fictional Madobe family tree detailed that Yū is the older sister, and their parents are Eiichi () from the Netsu (根津) family and Shii () from the Madobe family. Yū and Ai were said to have a birthdate of 18 November 1996 (Windows CE's release date) with age 15, with height of 152 cm. This conflicts with other back-story materials suggesting that Ai is the younger sister. MasatakaP and Electrocutica produced a Windows 8 music video titled "Through the Window", featuring Madobe characters Nanami, Yū (in silhouette), and Claudia. The video was presented as the opening to Microsoft's keynote on the second day of Windows Developer Days in Japan. In 2012 and 2013, Windows Navi+ (Techno-Alliance Corp.) also created separate Twitter accounts for Ai and Yū, respectively. Two theme songs for Yū and Ai – "Mir8cle Days" () and "Donna Mirai Demo" () were unveiled on 15 June 2013, and sold as a CD bundled with Windows 8 Pro DSP Edition, sold at TwinBox Akihabara. Windows 7 Akiba PC reported that the first 7777 copies of Japanese Windows 7 Ultimate DSP editions include special wallpaper and sound sets for a character called , voiced by Nana Mizuki. The character was designed by Wakaba. The premium set includes a Windows 7 theme featuring 3 Nanami wallpapers, 19 event sound sets, CD with 5 extra Nanami sounds. Regular DSP edition includes a digest Windows 7 theme including a Nanami wallpaper, an event sound set; the preorder users can also download an extra Nanami wallpaper and 6 event sound sets. This makes it the first OS-tan marketed by the company producing the operating system. In addition, the character also got its own Twitter account. During the initial sales event of the Windows 7 DSP edition, the official profile of the character has also been revealed. It shows Madobe Nanami was born in 1992-04-06 (release date of Windows 3.1) 17 years of age(at the time of release), who lives in Chiyoda, Tokyo. Nanami is among an extended family of 16 members, and she has elder brother named Goichi (吾一), elder sister named Mutsumi (むつみ), mother named Mikaho (美佳穗) from Madobe (窓辺) family, father named Kyuuachi (究八) from Shirato (白戸) family. Nanami and her cousin Claudia Madobe (クロード(蔵人)) later appeared in Microsoft's Cloud Girl comic strip. Original OS-tans Windows Vista Windows Vista's most distinguishing characteristic is usually her horn-shaped pigtails (some variants have up to four pigtails) and heterochromatic eyes. Silver or white hair appears to be the most frequent, although light blue and black are also seen. A common costume design was a white and red sailor fuku and stockings. Since the release of more details about Vista's interface, her look has changed slightly. A black maid's outfit is now emerging in popularity (which matches the new default Vista color scheme), as well as a circular Windows logo hair clip, identical to the new Start Menu button in Vista. There also seems to be a more finalized version who has a hair color similar to that of Vista wallpapers, with a range from light blue, to yellow, to green. She also wears a type of long coat (which only covers her left and right sides) which are transparent to imitate that of the Aero glass effect. Windows XP XP-tan is a dark-haired girl with ribbons in her hair and an "XP" hair ornament typically worn on the left side. As Windows XP is criticized for bloating a system and being very pretty without being as useful, XP-tan is commonly depicted wearing tight clothing with big breasts. Additionally, as a reference to the memory usage of Windows XP, she is often seen eating or holding an empty rice bowl labeled "Memory". Some variants include a version for XP Home known as "Homeko" who has green hair which she wears in a short ponytail with two large XP-shaped hairclips that cover her ears, as well as a less common variation representing Windows XP Media Center Edition. The outfits worn by the two main variants are based on the loading lines at the Windows splash screen during startup. And XP tan can handle a max of 4 GB of RAM (3.5 GB she can use). Windows 2000 Although a few variants exist, the most common operating system represented is Windows 2000 Professional. She is typically drawn as an intelligent, professional, reserved looking woman with short blue hair, glasses, and hair clips that resemble cat ears flanking a small white bonnet or ruffle, similar to a maid's bonnet, that shows the Windows logo. Her outfit resembles a swimsuit suggesting the Windows logo colors worn with long blue coat, alluding to the popular opinion that Windows 2000 is the most stable and dependable of the Windows operating systems. Due to the greater stability of Win2K compared with WinME, which was released near 2000, 2K-tan is often described as the guardian of ME-tan. The particular shade of blue used in most drawings is similar to the default Windows 2000 desktop color. Windows ME The design of ME-tan, the personification of Windows Me, is very much in line with the Japanese concept of kawaii or cuteness. Her design has changed little from the artist's original designs and is depicted with green hair in long pigtails wearing a maid outfit with a "!" badge on the front reminiscent of the Windows Me Active Desktop Recovery screen, often shown after rebooting from a system crash in Me. While she is considered to be a hard worker, webcomics often depict her failing at anything she tries to do, often literally crashing and irritating her sisters. When she is not frozen or out of control, she tends to do things showing a lack of common sense or knowledge, such as putting a soda can into a microwave oven or defending herself by swinging a Welsh onion. Windows 98 and 98SE While many variations exist the most common depiction of the Windows 98 operating systems is a pair of young girls. The OS-tan representative of the original release of Windows 98 is shown in a white and blue uniform that includes the Windows logo as part of a neck tie, navy blue hair, and a "98" hair clip. The Windows 98 Second Edition OS-tan is similar in appearance, but wears a green sailor school uniform with the letters "SE" on the front. Two early representations that are also seen are a pair of stick-limbed Pocky boxes with a face and version number drawn in crayon. This is a reference to Vulcan 300, a character from the Zatch Bell! anime series. These early representations are still used as a mecha piloted by the girls, dolls carried by the girls, or sometimes even as hiding places for them. Windows 95 As Windows 95 is considered to be the oldest of the modern 32-bit Windows operating systems, it is usually represented as a traditional lady from the early modern era of Japan. She is typically depicted as a gentle-looking brown haired woman in a kimono, with a hair ribbon showing the four Windows colors. Her outfit is a traditional kimono and a hakama of Japan and she wears thick sandals, or geta, on her feet. These were a woman college student's typical clothes as seen in the earliest period during the course of the modernization in Japan (from the Meiji period to the Taishō period) and is a reference to the modernization of Windows in comparison to the modernization of Japan. Additionally, the pattern of her kimono is based on the file "hana256.bmp", which was used as a desktop wallpaper pattern in the Japanese version of Windows. She is typically depicted as engaged in drinking tea, serving meals or doing other housework. One recurring theme in stories is her unfamiliarity with newer, post Win-95 technologies, such as USB devices (even though the OSR 2.x supported it) and broadband internet connections. She is also occasionally depicted wielding a katana in an aggressive manner, symbolizing that it was with her generation of operating systems that Microsoft finally achieved full dominance of the personal computer market. Windows 3.1 Windows 3.1 is a short girl with long silver hair, a long light purple dress, and a large purple bow on her head. She is often seen carrying a small, black cat on her head as well. She acts as a servant, or a maid of some sort, who serves and tends to DOS-tan. This is a reference to the fact that Windows 3.1 is not a full operating system, but rather just a GUI for MS-DOS. Mac OS X The Mac OS X girl is often portrayed as a catgirl, following with the Apple "wild cat" naming tradition (every Mac OS X release until OS X Mavericks had a codename like Jaguar, Panther, Tiger, Snow Leopard, etc.). Otherwise, she is shown as an older variation of the Mac OS 9 girl, wearing a white coat and wearing an AirPort wireless hub fashioned as a hat. She is occasionally shown holding a publication of some sort, as Macs are often used for desktop publishing. Linux Originally seen as a bearded penguin (a reference to Tux, the penguin mascot of the Linux kernel), an image of a girl with a helmet and flippers was chosen as a human alternative. Her helmet (most likely a metaphor for the Linux kernel's oft-claimed excellent security) usually has horns on it, likely a reference to the GNU software which comprises the common system programs present in nearly all Linux distributions. The gear teeth on the helmet are a reference to KDE, a common desktop environment used with Linux. The foot symbol on her shirt is a reference to GNOME, another common desktop environment. She is often seen with a spear that has flags attached representing the GRUB, LILO and GCC tools for Linux. MSX-DOS The MSX-DOS girl is often portrayed as a young but grey-haired girl carrying a large cartridge-shaped bag with an MSX-DOS logo on it. There is even a short game featuring this OS-tan as player character. The bag this OS-tan is often shown holding is cartridge-shaped, likely because MSXDOS2 required an cartridge with an extra 64 KB of ROM in order to work. American -tan Some Americanized versions of Windows related OS-tan, named XP-USA, Me-USA, and 2K-USA, were published in the Ohzora's FanBook in a comic strip named "Trouble Windows in USA", by Saint Muscle. Supporting characters Because of heavy associations between operating systems and their supporting programs, such as anti-virus clients and Web browsers, many supporting characters have been created to personify the idiosyncrasies of these applications. Some examples are: Amazon Kindle: Kindle-kun Chromium: Chrome-tan DOS: DOS-tan Internet Explorer/Microsoft Edge: Inori Aizawa (IE-tan) McAfee: Miss McAfee Mozilla Firefox: Firefox-tan; Foxkeh Norton Utilities: Dr. Norton Opera: Opera-tan Silverlight: Hikaru Aizawa Microsoft Azure: Claudia Madobe Critical receptionWired News'' rated OS-tan among the "Lamest Technology Mascots Ever", yet "strangely compelling". See also CG artwork Mecha Musume Moe anthropomorphism List of computing mascots References External links OS-tan Collections Wiki Doujinshi Anime and manga fandom Moe anthropomorphism OS-tan and related characters Internet memes Operating system advocacy

Operating System (OS)

System generation In computing system generation or sysgen is the process of creating a particular unique instance of an operating system by combining user-specified options and parameters with manufacturer-supplied general-purpose program code to produce an operating system tailored for a particular hardware and software environment. Some other programs have similar processes, although not usually called "sysgen." For example, IBM's Customer Information Control System (CICS) was installed through a process called CICSGEN. Rationale A large general-purpose program such as an operating system has to provide support for all variations of Central processing unit (CPU) that it might be run on, for all supported main memory sizes, and for all possible configurations of input/output (I/O) equipment. No one installation requires all this support, so system generation provides a process for selecting the options and features actually required on any one system. Sysgen produces a system that is most efficient in terms of CPU time, main memory requirements, I/O activity, and/or disk space. Often these parameters can be traded off, for example to generate a system that requires less memory at the expense of increased disk I/O operations. See also System Generation (OS) References System software

Operating System (OS)

Live CD A live CD (also live DVD, live disc, or live operating system) is a complete bootable computer installation including operating system which runs directly from a CD-ROM or similar storage device into a computer's memory, rather than loading from a hard disk drive. A live CD allows users to run an operating system for any purpose without installing it or making any changes to the computer's configuration. Live CDs can run on a computer without secondary storage, such as a hard disk drive, or with a corrupted hard disk drive or file system, allowing data recovery. As CD and DVD drives have been steadily phased-out, live CDs have become less popular, being replaced by live USBs, which are equivalent systems written onto USB flash drives, which have the added benefit of having writeable storage. The functionality of a live CD is also available with an external hard disk drive connected by USB. Many live CDs offer the option of persistence by writing files to a hard drive or USB flash drive. Many Linux distributions make ISO images available for burning to CD or DVD. While open source operating systems can be used for free, some commercial software, such as Windows To Go requires a license to use. Many live CDs are used for data recovery, computer forensics, disk imaging, system recovery and malware removal. The Tails operating system is aimed at preserving privacy and anonymity of its users, allowing them to work with sensitive documents without leaving a record on a computer's hard drive. History All computers except the earliest digital computers are built with some form of minimal built-in loader, which loads a program or succession of programs from a storage medium, which then operate the computer. Initially a read-only medium such as punched tape or punched cards was used for initial program load. With the introduction of inexpensive read-write storage, read-write floppy disks and hard disks were used as boot media. After the introduction of the audio compact disc, it was adapted for use as a medium for storing and distributing large amounts of computer data. This data may also include application and operating-system software, sometimes packaged and archived in compressed formats. Later, it was seen to be convenient and useful to boot the computer directly from compact disc, often with a minimal working system to install a full system onto a hard drive. While there are read-write optical discs, either mass-produced read-only discs or write-once discs were used for this purpose. The first Compact Disc drives on personal computers were generally much too slow to run complex operating systems; computers were not designed to boot from an optical disc. When operating systems came to be distributed on compact discs, either a boot floppy or the CD itself would boot specifically, and only, to install onto a hard drive. The world's first and oldest non-Linux live CD was the FM Towns OS first released in 1989, before the release of Macintosh System 7 in 1991 and Yggdrasil Linux in 1992. Linux Although early developers and users of distributions built on top of the Linux kernel could take advantage of cheap optical disks and rapidly declining prices of CD drives for personal computers, the Linux distribution CDs or "distros" were generally treated as a collection of installation packages that would first need to be permanently installed to hard disks on the target machine. However, in the case of these distributions built on top of the Linux kernel, the free operating system was meeting resistance in the consumer market because of the perceived difficulty, effort, and risk involved in installing an additional partition on the hard disk, in parallel with an existing operating system installation. The term "live CD" was coined because, after typical PC RAM was large enough and 52x speed CD drives and CD burners were widespread among PC owners, it finally became convenient and practical to boot the kernel and run X11, a window manager and GUI applications directly from a CD without disturbing the OS on the hard disk. This was a new and different situation for Linux than other operating systems, because the updates/upgrades were being released so quickly, different distributions and versions were being offered online, and especially because users were burning their own CDs. The first Linux-based 'Live CD' was Yggdrasil Linux first released in beta form 1992~1993 (ceased production in 1995), though in practice its functionality was hampered due to the low throughput of contemporary CD-ROM drives. DemoLinux, released in 1998, was the first Linux distribution specially designed as a live CD. The Linuxcare bootable business card, first released in 1999, was the first Live CD to focus on system administration, and the first to be distributed in the bootable business card form factor. , Finnix (first released in 2000) is the oldest Live CD still in production. Knoppix, a Debian-derived Linux distribution, was released in 2003, and found popularity as both a rescue disk system and as a primary distribution in its own right. Since 2003, the popularity of live CDs has increased substantially, partly due to Linux Live scripts and remastersys, which made it very easy to build customized live systems. Most of the popular Linux distributions now include a live CD variant, which in some cases is also the preferred installation medium. Uses Live CDs are made for many different uses. Some are designed to demonstrate or "test drive" a particular operating system (usually Linux or another free or open source operating system). Software can be tested, or run for a particular single use, without interfering with system setup. Data on a system which is not functioning normally due to operating system and software issues can be made available; for example, data can be recovered from a machine with an active virus infection without the virus process being active and causing more damage, and the virus can be removed with its defences against removal bypassed. Although some live CDs can load into memory to free the optical drive for other uses, loading the data from a CD-ROM is still slower than a typical hard drive boot, so this is rarely the default with large live CD images, but for smaller live CD images loading the filesystem directly into RAM can provide a significant performance boost, as RAM is much faster than a hard drive, and uses less power. Experienced users of the operating system may also use a live CD to determine whether and to what extent a particular operating system or version is compatible with a particular hardware configuration and certain peripherals, or as a way to know beforehand which computer or peripheral will work before buying. A live CD can be used to troubleshoot hardware, especially when a hard drive fails, and more generally as a recovery disc in case of problems. Some live CDs can save user-created files in a Windows partition, a USB drive, a network drive, or other accessible media. Live backup CDs can create an image of drives, and back up files, without problems due to open files and inconsistent sets. A few additional uses include: installing a Linux distribution to a hard drive computer forensics Virus scanning and Malware removal system repair and restoration testing new versions of software listing & testing hardware Internet kiosks and public computers, which can be brought back to their original state by a reboot high security/non-invasive environment for a guest cracking, stealing, and changing passwords network security testing being the primary or backup operating system for any computer quick and simple clustering of computers playing video games or running applications that require a different operating system providing a secure server platform where crucial files cannot be permanently altered providing a secure, reliable platform for the performance of high-vulnerability tasks such as internet banking; Bypassing parental controls and other restrictions Several live CDs are dedicated to specific type of applications according to the requirements of thematic user communities. These CDs are tailored to the needs of the applications in subject including general knowledge, tutorial, specifications and trial data too. Some of these topics covers sub topics, e.g. IT administration breaks down to firewall, rescue, security, etc. type of live CDs. In some cases a particular Live DVD covers more than one topic. Software appliances Packaging a software appliance as an installable live CD, or live ISO, can often be beneficial as a single image can run on both real hardware and on most types of virtual machines. This allows developers to avoid the complexities involved in supporting multiple incompatible virtual machine images formats and focus on the lowest common denominator instead. Typically after booting the machine from the live CD, the appliance either runs in non-persistent demo mode or installs itself, at the user's request, to an available storage device. Mounting without burning The files on a live CD ISO image can be accessed in Microsoft Windows with a disk image emulator such as Daemon Tools, or in Unix variants by mounting a loop device. Later versions of Windows (i.e. Windows 8 and later), and software available for earlier versions, allow an ISO to be mounted as a volume. After mounting the live CD's filesystem, software on the live CD can be run directly, without booting it, by chrooting into the mounted filesystem. A live CD ISO image can also be mounted by Virtual Machine software such as VirtualBox and VMware Workstation or can be converted to a Live USB using SYSLINUX. Special tools can automate this process. Features During live CD initialization, a user typically may resort to using one or more boot codes to change the booting behavior. These vary from distribution to distribution but can most often be accessed upon first boot screen by one of the function keys. Some live CDs come with an installation utility launchable from a desktop icon that can optionally install the system on a hard drive or USB flash drive. Most live CDs can access the information on internal and/or external hard drives, diskettes and USB flash drives. Live CDs are usually distributed on read-only media, requiring either copying to rewriteable media (i.e. a hard drive or CD writer) or complete remastering to install additional software; however, there are exceptions. If Puppy Linux is recorded to an open multisession medium, changes made during use (such as files created, programs installed, and preferences customised) are written in a new session to the boot medium persisting through subsequent boots. The term "Live CD" came to be used for any CD containing operating system and software which could be run without installation on the host computer. Operating systems which can be used live include AmigaOS 4, Amithlon, AROS, FreeBSD, FreeDOS, classic Mac OS, macOS, Microsoft Windows installation and repair discs, OS/2, ReactOS, NetBSD, OpenBSD, MINIX 3, Plan 9 from Bell Labs, MorphOS, OpenSolaris, BeleniX and others based on Solaris. There are maintenance versions of Microsoft Windows bootable from CD such as BartPE, Windows PE, and Microsoft Diagnostics and Recovery Toolset (DaRT), previously known as Emergency Repair Disk Commander (ERD Commander). The first personal computer operating system on a CD to support "live" operations might have been the AmigaOS, which could be booted from CD on an Amiga CDTV in 1990.. Earlier examples of live OS are of course the operating systems used from floppy, and most widely spread is DOS. Unlike previous operating systems on optical media, though, Linux and OS/2 "live CDs" were specifically designed to run without installation onto other media like a hard disk drive. The live CD concept was meant to promote Linux and showcase the abilities of the free, open source operating system on conventional personal computers with Microsoft Windows already installed. On a PC, a bootable Compact Disc generally conforms to the El Torito specification, introduced in 1994. Many Linux based live CDs use a compressed filesystem image, often with the cloop compressed loopback driver, or squashfs compressed filesystem, generally doubling effective storage capacity, although slowing application start up. The resulting environment can be quite rich: typical Knoppix systems include around 1,200 separate software packages. Live CDs have a reputation for supporting advanced auto-configuration and plug-and-play functionality. This came out of necessity to avoid requiring the user to configure the system each time it boots and to make it easily usable by those who are new to the operating system. Creation A read-only file system, such as on a CD-ROM has the drawback of being unable to save any current working data. For this reason, a read-only file system is often merged with a temporary writable file system in the form of a RAM disk. Often the default Linux directories "/home" (containing users' personal files and configuration files) and "/var" (containing variable data) are kept in ramdisk, because the system updates them frequently. Puppy Linux and some other live CDs allow a configuration and added files to be written and used in later sessions. In modern live CDs, a read-only file system is merged with a RAM drive using transparent techniques such as UnionFS, AuFS or EWF. Boot loaders like syslinux can boot ISO files from USB memory devices. Live CDs have to be able to detect and use a wide variety of hardware (including network cards, graphic cards etc.) in realtime, often using facilities such as udev, hotplug, hal, udisk etc.. which are a common part of all distributions based on Linux kernel 2.6. See also Boot disk Comparison of Linux distributions#Live media GIS Live DVD List of live CDs List of remastering software Live USB Self-booting diskette Software appliance Windows To Go References External links Bootable CDROM HowTo Linux Live scripts Pondering Live CDs - A BSD perspective on the concept of Live CDs Software appliances

Operating System (OS)

KERNAL KERNAL is Commodore's name for the ROM-resident operating system core in its 8-bit home computers; from the original PET of 1977, followed by the extended but strongly related versions used in its successors: the VIC-20, Commodore 64, Plus/4, C16, and C128. Description The Commodore 8-bit machines' KERNAL consists of the low-level, close-to-the-hardware OS routines roughly equivalent to the BIOS in IBM PC compatibles (in contrast to the BASIC interpreter routines, also located in ROM) as well as higher-level, device-independent I/O functionality, and is user-callable via a jump table in RAM whose central (oldest) part, for reasons of backwards compatibility, remains largely identical throughout the whole 8-bit series. The KERNAL ROM occupies the last 8 KB of the 8-bit CPU's 64 KB address space ($E000–$FFFF). The jump table can be modified to point to user-written routines, for example rewriting the screen display routines to display animated graphics or copying the character set into RAM. This use of a jump table was new to small computers at the time. The Adventure International games published for the VIC-20 on cartridge are an example of software that uses the KERNAL. Because they only use the jump table, the games can be memory dumped to disk, loaded into a Commodore 64, and run without modification. The KERNAL was initially written for the Commodore PET by John Feagans, who introduced the idea of separating the BASIC routines from the operating system. It was further developed by several people, notably Robert Russell, who added many of the features for the VIC-20 and the C64. Example A simple, yet characteristic, example of using the KERNAL is given by the following 6502 assembly language subroutine (written in ca65 assembler format/syntax): CHROUT = $ffd2 ; CHROUT is the address of the character output routine CR = $0d ; PETSCII code for Carriage Return ; hello: ldx #0 ; start with character 0 by loading 0 into the x index register next: lda message,x ; load byte from address message+x into the accumulator beq done ; if the accumulator holds zero, we're done and want to branch out of the loop jsr CHROUT ; call CHROUT to output char to current output device (defaults to screen) inx ; increment x to move to the next character bne next ; loop back while the last character is not zero (max string length 255 bytes) done: rts ; return from subroutine ; message: .byte "Hello, world!" .byte CR, 0 ; Carriage Return and zero marking end of string This code stub employs the CHROUT routine, whose address is found at address $FFD2 (65490), to send a text string to the default output device (e.g., the display screen). The name The KERNAL was known as kernel inside of Commodore since the PET days, but in 1980 Robert Russell misspelled the word as kernal in his notebooks. When Commodore technical writers Neil Harris and Andy Finkel collected Russell's notes and used them as the basis for the VIC-20 programmer's manual, the misspelling followed them along and stuck. According to early Commodore myth, and reported by writer/programmer Jim Butterfield among others, the "word" KERNAL is an acronym (or maybe more likely, a backronym) standing for Keyboard Entry Read, Network, And Link, which in fact makes good sense considering its role. Berkeley Softworks later used it when naming the core routines of its GUI OS for 8-bit home computers: the GEOS KERNAL. On device-independent I/O Surprisingly, the KERNAL implemented a device-independent I/O API not entirely dissimilar from that of Unix or Plan-9, which nobody actually exploited, as far as is publicly known. Whereas one could reasonably argue that "everything is a file" in these latter systems, others could easily claim that "everything is a GPIB-device" in the former. Due to limitations with the 6502 architecture at the time, opening an I/O channel requires three system calls. The first typically sets the logical filename through the SETNAM system call. The second call, SETLFS, establishes the GPIB/IEEE-488 "device" address to communicate with. Finally OPEN is called to perform the actual transaction. The application then used CHKIN and CHKOUT system calls to set the application's current input and output channels, respectively. Applications may have any number of concurrently open files (up to some system-dependent limit; e.g., the C64 allows for ten files to be opened at once). Thereafter, CHRIN and CHROUT prove useful for actually conducting input and output, respectively. CLOSE then closes a channel. Observe that no system call exists to "create" an I/O channel, for devices cannot be created or destroyed dynamically under normal circumstances. Likewise, no means exists for seeking, nor for performing "I/O control" functions such as ioctl() in Unix. Indeed, the KERNAL proves much closer to the Plan-9 philosophy here, where an application would open a special "command" channel to the indicated device to conduct such "meta" or "out-of-band" transactions. For example, to delete ("scratch") a file from a disk, the user typically will "open" the resource called S0:THE-FILE-TO-RMV on device 8 or 9, channel 15. Per established convention in the Commodore 8-bit world, channel 15 represents the "command channel" for peripherals, relying on message-passing techniques to communicate both commands and results, including exceptional cases. For example, in Commodore BASIC, they might find software not unlike the following: 70 ... 80 REM ROTATE LOGS CURRENTLY OPENED ON LOGICAL CHANNEL #1. 90 CLOSE 1 100 OPEN 15,8,15,"R0:ERROR.1=0:ERROR.0":REM RENAME FILE ERROR.0 TO ERROR.1 110 INPUT# 15,A,B$,C,D:REM READ ERROR CHANNEL 120 CLOSE 15 130 IF A=0 THEN GOTO 200 140 PRINT "ERROR RENAMING LOG FILE:" 150 PRINT " CODE: "+A 160 PRINT " MSG : "+B$ 170 END 200 REM CONTINUE PROCESSING HERE, CREATING NEW LOG FILE AS WE GO... 210 OPEN 1,8,1,"0:ERROR.0,S,W" 220 ... Device numbers, per established documentation, are restricted to the range [0,16]. However, this limitation came from the specific adaptation of the IEEE-488 protocol and, in effect, applies only to external peripherals. With all relevant KERNAL system calls vectored, programmers can intercept system calls to implement virtual devices with any address in the range of [32,256]. Conceivably, one can load a device driver binary into memory, patch the KERNAL I/O vectors, and from that moment forward, a new (virtual) device could be addressed. So far, this capability has never been publicly known as utilized, presumably for two reasons: (1) The KERNAL provides no means for dynamically allocating device IDs, and (2) the KERNAL provides no means for loading a relocatable binary image. Thus, the burden of collisions both in I/O space and in memory space falls upon the user, while platform compatibility across a wide range of machines falls upon the software author. Nonetheless, support software for these functions could easily be implemented if desired. Logical filename formats tends to depend upon the specific device addressed. The most common device used, of course, is the floppy disk system, which uses a format similar to MD:NAME,ATTRS, where M is a flag of sorts ($ for directory listing, @ for indicating a desire to overwrite a file if it already exists, unused otherwise.), D is the (optional) physical disk unit number (0: or 1: for dual-drive systems, just 0: for single-disk units like the 1541, et al., which defaults to 0: if left unspecified), NAME is a resource name up to 16 characters in length (most characters allowed except for certain special characters), and ATTRS is an optional comma-separated list of attributes or flags. For example, if the user wants to overwrite a program file called PRGFILE, they might see a filename like @0:PRGFILE,P used in conjunction with device 8 or 9. Meanwhile, a filename for the RS-232 driver (device 2) consists simply of four characters, encoded in binary format. Other devices, such as the keyboard (device 0), cassette (device 1), the display interface (device 3), and printer (device 4 and 5), require no filenames to function, either assuming reasonable defaults or simply not needing them at all. Notes External links Commodore KERNAL History Commodore 64 KERNAL I/O Monitor Utility Operating system kernels Commodore 64 Nonstandard spelling 1977 software

Operating System (OS)

MVS Multiple Virtual Storage, more commonly called MVS, was the most commonly used operating system on the System/370 and System/390 IBM mainframe computers. IBM developed MVS, along with OS/VS1 and SVS, as a successor to OS/360. It is unrelated to IBM's other mainframe operating system lines, e.g., VSE, VM, TPF. Overview First released in 1974, MVS was extended by program products with new names multiple times: first to MVS/SE (MVS/System Extensions), next to MVS/SP (MVS/System Product) Version 1, next to MVS/XA (MVS/eXtended Architecture), next to MVS/ESA (MVS/Enterprise Systems Architecture), then to OS/390 and finally to z/OS (when 64-bit support was added with the zSeries models). IBM added UNIX support (originally called OpenEdition MVS) in MVS/SP V4.3 and has obtained POSIX and UNIX™ certifications at several different levels from IEEE, X/Open and The Open Group. The MVS core remains fundamentally the same operating system. By design, programs written for MVS run on z/OS without modification. At first IBM described MVS as simply a new release of OS/VS2, but it was, in fact a major rewrite. OS/VS2 release 1 was an upgrade of OS/360 MVT that retained most of the original code and, like MVT, was mainly written in assembly language. The MVS core was almost entirely written in Assembler XF, although a few modules were written in PL/S, but not the performance-sensitive ones, in particular not the Input/Output Supervisor (IOS). IBM's use of "OS/VS2" emphasized upwards compatibility: application programs that ran under MVT did not even need recompiling to run under MVS. The same Job Control Language files could be used unchanged; utilities and other non-core facilities like TSO ran unchanged. IBM and users almost unanimously called the new system MVS from the start, and IBM continued to use the term MVS in the naming of later major versions such as MVS/XA. Evolution of MVS OS/360 MFT (Multitasking with a Fixed number of Tasks) provided multitasking: several memory partitions, each of a fixed size, were set up when the operating system was installed and when the operator redefined them. For example, there could be a small partition, two medium partitions, and a large partition. If there were two large programs ready to run, one would have to wait until the other finished and vacated the large partition. OS/360 MVT (Multitasking with a Variable number of Tasks) was an enhancement that further refined memory use. Instead of using fixed-size memory partitions, MVT allocated memory to regions for job steps as needed, provided enough contiguous physical memory was available. This was a significant advance over MFT's memory management, but had some weaknesses: if a job allocated memory dynamically (as most sort programs and database management systems do), the programmers had to estimate the job's maximum memory requirement and pre-define it for MVT. A job step that contained a mix of small and large programs wasted memory while the small programs ran. Most seriously, memory could become fragmented, i.e., the memory not used by current jobs could be divided into uselessly small chunks between the areas used by current jobs, and the only remedy was to wait until some current jobs finished before starting any new ones. In the early 1970s IBM sought to mitigate these difficulties by introducing virtual memory (which IBM called "virtual storage"), which allowed programs to request address spaces larger than physical memory. The original implementations had a single virtual address space, shared by all jobs. OS/VS1 was OS/360 MFT within a single virtual address space; OS/VS2 SVS was OS/360 MVT within a single virtual address space. So OS/VS1 and SVS in principle had the same disadvantages as MFT and MVT, but the impacts were less severe because jobs could request much larger address spaces and the requests came out of a 16 MB pool even if physical storage was smaller. In the mid-1970s IBM introduced MVS, which not only supported virtual storage that was larger than the available real storage, as did SVS, but also allowed an indefinite number of applications to run in different address spaces. Two concurrent programs might try to access the same virtual memory address, but the virtual memory system redirected these requests to different areas of physical memory. Each of these address spaces consisted of three areas: an operating system (one instance shared by all jobs), an application area unique for each application, and a shared virtual area used for various purposes, including inter-job communication. IBM promised that application areas would always be at least 8 MB. This made MVS the perfect solution for business problems that resulted from the need to run more applications. MVS maximized processing potential by providing multiprogramming and multiprocessing capabilities. Like its MVT and OS/VS2 SVS predecessors, MVS supported multiprogramming; program instructions and associated data are scheduled by a control program and given processing cycles. Unlike a single-programming operating system, these systems maximize the use of the processing potential by dividing processing cycles among the instructions associated with several different concurrently running programs. This way, the control program does not have to wait for the I/O operation to complete before proceeding. By executing the instructions for multiple programs, the computer is able to switch back and forth between active and inactive programs. Early editions of MVS (mid-1970s) were among the first of the IBM OS series to support multiprocessor configurations, though the M65MP variant of OS/360 running on 360 Models 65 and 67 had provided limited multiprocessor support. The 360 Model 67 had also hosted the multiprocessor capable TSS/360, MTS and CP-67 operating systems. Because multiprocessing systems can execute instructions simultaneously, they offer greater processing power than single-processing system. As a result, MVS was able to address the business problems brought on by the need to process large amounts of data. Multiprocessing systems are either loosely coupled, which means that each computer has access to a common workload, or tightly coupled, which means that the computers share the same real storage and are controlled by a single copy of the operating system. MVS retained both the loosely coupled multiprocessing of Attached Support Processor (ASP) and the tightly coupled multiprocessing of OS/360 Model 65 Multiprocessing. In tightly coupled systems, two CPUs shared concurrent access to the same memory (and copy of the operating system) and peripherals, providing greater processing power and a degree of graceful degradation if one CPU failed. In loosely coupled configurations each of a group of processors (single and / or tightly coupled) had its own memory and operating system but shared peripherals and the operating system component JES3 allowed managing the whole group from one console. This provided greater resilience and let operators decide which processor should run which jobs from a central job queue. MVS JES3 gave users the opportunity to network together two or more data processing systems via shared disks and Channel-to-Channel Adapters (CTCA's). This capability eventually became available to JES2 users as Multi-Access SPOOL (MAS). MVS originally supported 24-bit addressing (i.e., up to 16 MB). As the underlying hardware progressed, it supported 31-bit (XA and ESA; up to 2048 MB) and now (as z/OS) 64-bit addressing. The most significant motives for the rapid upgrade to 31-bit addressing were the growth of large transaction-processing networks, mostly controlled by CICS, which ran in a single address space—and the DB2 relational database management system needed more than 8 MB of application address space to run efficiently. (Early versions were configured into two address spaces that communicated via the shared virtual area, but this imposed a significant overhead since all such communications had transmit via the operating system.) The main user interfaces to MVS are: Job Control Language (JCL), which was originally designed for batch processing but from the 1970s onwards was also used to start and allocate resources to long-running interactive jobs such as CICS; and TSO (Time Sharing Option), the interactive time-sharing interface, which was mainly used to run development tools and a few end-user information systems. ISPF is a TSO application for users on 3270-family terminals (and later, on VM as well), which allows the user to accomplish the same tasks as TSO's command line but in a menu and form oriented manner, and with a full screen editor and file browser. TSO's basic interface is command line, although facilities were added later for form-driven interfaces. MVS took a major step forward in fault-tolerance, built on the earlier STAE facility, that IBM called software recovery. IBM decided to do this after years of practical real-world experience with MVT in the business world. System failures were now having major impacts on customer businesses, and IBM decided to take a major design jump, to assume that despite the very best software development and testing techniques, that 'problems WILL occur.' This profound assumption was pivotal in adding great percentages of fault-tolerance code to the system and likely contributed to the system's success in tolerating software and hardware failures. Statistical information is hard to come by to prove the value of these design features (how can you measure 'prevented' or 'recovered' problems?), but IBM has, in many dimensions, enhanced these fault-tolerant software recovery and rapid problem resolution features, over time. This design specified a hierarchy of error-handling programs, in system (kernel/'privileged') mode, called Functional Recovery Routines, and in user ('task' or 'problem program') mode, called "ESTAE" (Extended Specified Task Abnormal Exit routines) that were invoked in case the system detected an error (hardware processor or storage error, or software error). Each recovery routine made the 'mainline' function reinvokable, captured error diagnostic data sufficient to debug the causing problem, and either 'retried' (reinvoke the mainline) or 'percolated' (escalated error processing to the next recovery routine in the hierarchy). Thus, with each error the system captured diagnostic data, and attempted to perform a repair and keep the system up. The worst thing possible was to take down a user address space (a 'job') in the case of unrepaired errors. Though it was an initial design point, it was not until the most recent MVS version (z/OS), that recovery program was not only guaranteed its own recovery routine, but each recovery routine now has its own recovery routine. This recovery structure was embedded in the basic MVS control program, and programming facilities are available and used by application program developers and 3rd party developers. Practically, the MVS software recovery made problem debugging both easier and more difficult. Software recovery requires that programs leave 'tracks' of where they are and what they are doing, thus facilitating debugging—but the fact that processing progresses despite an error can overwrite the tracks. Early data capture at the time of the error maximizes debugging, and facilities exist for the recovery routines (task and system mode, both) to do this. IBM included additional criteria for a major software problem that required IBM service. If a mainline component failed to initiate software recovery, that was considered a valid reportable failure. Also, if a recovery routine failed to collect significant diagnostic data such that the original problem was solvable by data collected by that recovery routine, IBM standards dictated that this fault was reportable and required repair. Thus, IBM standards, when rigorously applied, encouraged continuous improvement. IBM continued to support the major serviceability tool Dynamic Support System (DSS) that it had introduced in OS/VS1 and OS/VS2 Release 1. This interactive facility could be invoked to initiate a session to create diagnostic procedures, or invoke already-stored procedures. The procedures trapped special events, such as the loading of a program, device I/O, system procedure calls, and then triggered the activation of the previously defined procedures. These procedures, which could be invoked recursively, allowed for reading and writing of data, and alteration of instruction flow. Program Event Recording hardware was used. IBM dropped support for DSS with Selectable Unit 7 (SU7), an update to OS/VS2 Release 3.7 required by the program product OS/VS2 MVS/System Extensions (MVS/SE), Program Number 5740-XEl. The User group SHARE passed a requirement that IBM reinstate DSS, and IBM provided a PTF to allow use of DSS after MVS/SE was installed. IBM again dropped support for DSS with SU64, an update to OS/VS2 Release 3.8 required by Release 2 of MVS/SE. Program-Event Recording (PER) exploitation was performed by the enhancement of the diagnostic SLIP command with the introduction of the PER support (SLIP/Per) in SU 64/65 (1978). Multiple copies of MVS (or other IBM operating systems) could share the same machine if that machine was controlled by VM/370. In this case VM/370 was the real operating system, and regarded the "guest" operating systems as applications with unusually high privileges. As a result of later hardware enhancements one instance of an operating system (either MVS, or VM with guests, or other) could also occupy a Logical Partition (LPAR) instead of an entire physical system. Multiple MVS instances can be organized and collectively administered in a structure called a systems complex or sysplex, introduced in September, 1990. Instances interoperate through a software component called a Cross-system Coupling Facility (XCF) and a hardware component called a Hardware Coupling Facility (CF or Integrated Coupling Facility, ICF, if co-located on the same mainframe hardware). Multiple sysplexes can be joined via standard network protocols such as IBM's proprietary Systems Network Architecture (SNA) or, more recently, via TCP/IP. The z/OS operating system (MVS' most recent descendant) also has native support to execute POSIX and Single UNIX Specification applications. The support began with MVS/SP V4R3, and IBM has obtained UNIX 95 certification for z/OS V1R2 and later. The system is typically used in business and banking, and applications are often written in COBOL. COBOL programs were traditionally used with transaction processing systems like IMS and CICS. For a program running in CICS, special EXEC CICS statements are inserted in the COBOL source code. A preprocessor (translator) replaces those EXEC CICS statements with the appropriate COBOL code to call CICS before the program is compiled — not altogether unlike SQL used to call DB2. Applications can also be written in other languages such as C, C++, Java, assembly language, FORTRAN, BASIC, RPG, and REXX. Language support is packaged as a common component called "Language Environment" or "LE" to allow uniform debugging, tracing, profiling, and other language independent functions. MVS systems are traditionally accessed by 3270 terminals or by PCs running 3270 emulators. However, many mainframe applications these days have custom web or GUI interfaces. The z/OS operating system has built-in support for TCP/IP. System management, done in the past with a 3270 terminal, is now done through the Hardware Management Console (HMC) and, increasingly, Web interfaces. Operator consoles are provided through 2074 emulators, so you are unlikely to see any S/390 or zSeries processor with a real 3270 connected to it. The native character encoding scheme of MVS and its peripherals is EBCDIC, but the TR instruction made it easy to translate to other 7- and 8-bit codes. Over time IBM added hardware-accelerated services to perform translation to and between larger codes, hardware-specific service for Unicode transforms and software support of, e.g., ASCII, ISO/IEC 8859, UTF-8, UTF-16, and UTF-32. The software translation services take source and destination code pages as inputs. MVS filesystem Files, other than Unix files, are properly called data sets in MVS. Names of those files are organized in catalogs that are VSAM files themselves. Data set names (DSNs, mainframe term for filenames) are organized in a hierarchy whose levels are separated with dots, e.g. "DEPT01.SYSTEM01.FILE01". Each level in the hierarchy can be up to eight characters long. The total filename length is a maximum of 44 characters including dots. By convention, the components separated by the dots are used to organize files similarly to directories in other operating systems. For example, there were utility programs that performed similar functions to those of Windows Explorer (but without the GUI and usually in batch processing mode) - adding, renaming or deleting new elements and reporting all the contents of a specified element. However, unlike in many other systems, these levels are not usually actual directories but just a naming convention (like the original Macintosh File System, where folder hierarchy was an illusion maintained by the Finder). TSO supports a default prefix for files (similar to a "current directory" concept), and RACF supports setting up access controls based on filename patterns, analogous to access controls on directories on other platforms. As with other members of the OS family, MVS' data sets were record-oriented. MVS inherited three main types from its predecessors: Sequential data sets were normally read one record at a time from beginning to end. In BDAM (direct access) data sets, the application program had to specify the physical location of the data it wanted to access (usually by specifying the offset from the start of the data set). In ISAM data sets a specified section of each record was defined as a key that could be used as a key to look up specific records. The key quite often consisted of multiple fields but these had to be contiguous and in the right order; and key values had to be unique. Hence an IBM ISAM file could have only one key, equivalent to the primary key of a relational database table; ISAM could not support foreign keys. Sequential and ISAM datasets could store either fixed-length or variable length records, and all types could occupy more than one disk volume. All of these are based on the VTOC disk structure. Early IBM database management systems used various combinations of ISAM and BDAM datasets - usually BDAM for the actual data storage and ISAM for indexes. In the early 1970s IBM's virtual memory operating systems introduced a new file management component, VSAM, which provided similar facilities: Entry-Sequenced Datasets (ESDS) provided facilities similar to those of both sequential and BDAM datasets, since they could be read either from start to finish or directly by specifying an offset from the start. Key-Sequenced Datasets (KSDS) were a major upgrade from ISAM: they allowed secondary keys with non-unique values and keys formed by concatenating non-contiguous fields in any order; they greatly reduced the performance problems caused by overflow records in ISAM; and they greatly reduced the risk that a software or hardware failure in the middle of an index update might corrupt the index. These VSAM formats became the basis of IBM's database management systems, IMS/VS and DB2 - usually ESDS for the actual data storage and KSDS for indexes. VSAM also included a catalog component used for user catalogs and MVS' master catalog. Partitioned data sets (PDS) were sequential data sets subdivided into "members" that could each be processed as sequential files in their own right (like a folder in a hierarchical file system). The most important use of PDSes was for program libraries - system administrators used the main PDS as a way to allocate disk space to a project and the project team then created and edited the members. Other uses of PDSs were libraries of frequently used job control procedures (PROCs), and "copy books" of programming language statements such as record definitions used by several programs. Generation Data Groups (GDGs) are groups of like named data sets, which can be referenced by absolute generation number, or by an offset from the most recent generation. They were originally designed to support grandfather-father-son backup procedures - if a file was modified, the changed version became the new "son", the previous "son" became the "father", the previous "father" became the "grandfather" and the previous "grandfather" was deleted. But one could set up GDGs with more than 3 generations and some applications used GDGs to collect data from several sources and feed the information to one program - each collecting program created a new generation of the file and the final program read the whole group as a single sequential file (by not specifying a generation in the JCL). Modern versions of MVS (e.g., z/OS) use datasets as containers for Unix filesystems along with facilities for partially integrating them. That is, Unix programs using fopen() can access an MVS dataset and a user can allocate a Unix file as though it were a dataset, with some restrictions. The Hierarchical File System (HFS) (not to be confused with Apple's Hierarchical File System) uses a unique type of dataset, while the newer z/OS File System (zFS) (not to be confused with Sun's ZFS) uses a VSAM Linear Data Set (LDS). Programs running on network-connected computers (such as the IBM AS/400) can use local data management interfaces to transparently create, manage, and access VSAM record-oriented files by using client-server products implemented according to Distributed Data Management Architecture (DDM). DDM is also the base architecture for the MVS DB2 server that implements Distributed Relational Database Architecture (DRDA). Upgrades to MVS In addition to new functionality that IBM added with releases and sub-releases of OS/VS2, IBM provided a number of free Incremental Change Releases (ICRs) and Selectable Units (SUs) and chargeable program products and field developed programs that IBM eventually bundled as part of z/OS. These include: ACF/TCAM (5735-RCl) ACF/VTAM (5746-RC3, 5735-RC2) Data Facility/Device Support (DF/DS), 5740-AM7 Data Facility Extended Function (DF/EF), 5740-XYQ Data Facility/Data Set Services (DF/DSS), 5740-UT3. Data Facility Sort, 5740-SM1 OS/VS2 MVS Sequential Access Method-Extended (SAM-E), 5740-AM3 MVS/370 Data Facility Product (DFP), 5665-295, replacing 5740-AM7 Data Facility Device Support (DFDS) 5740-XYQ Data Facility Extended Function (DFEF) 5740-AM3 Sequential Access Method Extended (SAM-E) 5740-AM8 Access Method Services Cryptographic Option 5748-UT2 Offline 3800 Utility MVS/XA Data Facility Product Version 1 Release 1, 5665-284 MVS/XA Data Facility Product Version 2 Release 1, 5665-XA2 MVS/ESA Data Facility Product Version 3, 5665-XA3 Data Facility Storage Management Subsystem (DFSMS), 5695-DF1Replaces DFP, DF/DSS and DF/HSM OS/VS2 MVS TSO Command Package (5740-XT6) TSO Command Processor - FDP 5798-AYF (PRINT command) TSO/VS2 Programming Control Facility - FDP 5798-BBJ TSO Programming Control Facility - II (PCF II), FDP 5798-CLW, TSO ExtensionsReplaces TSO Command Package, TSO Command Processor and PCF 5665-285 for MVS/370 5665-293 for MVS/XA 5685-025 for MVS/XAFirst version with REXX OS/VS2 MVS/System Extensions, 5740-XEl MVS/System Product JES3 Version 1 5740-XYN JES2 Version 1 5740-XYS MVS/System Product-JES2 Version 2, 5740-XC6 MVS/System Product-JES3 Version 2, 5665-291 MVS/System Product-JES2 Version 3, 5685-001 MVS/System Product-JES3 Version 3, 5685-002 MVS/ESA System Product: JES2 Version 4, 5695-047 MVS/ESA System Product: JES3 Version 4, 5695-048 MVS/ESA System Product: JES2 Version 5, 5655-068 MVS/ESA System Product: JES3 Version 5, 5655-069 Data Facility Product (DFP) In the late seventies and early eighties IBM announced: 5740-AM7 Data Facility Device Support (DF/DS) 5740-XYQ Data Facility Extended Function (DF/EF) 5740-AM3 Sequential Access Method Extended (SAM-E) 5740-AM8 Access Method Services Cryptographic Option 5748-UT2 Offline 3800 Utility DF/DS added new device support, and IBM announced that it would no longer add device support to the free base. DF/EF added the Improved Catalog Structure (ICF) as an alternative to VSAM catalogs and Control Volumes (CVOLs), but it was riddled with reliability problems. When IBM announced MVS/SP Version 2 (MVS/XA), it also announced Data Facility Product™ (DFP™) as a replacement for and upgrade to the other five products above, which it said would be withdrawn from marketing, effective December 1, 1984. DFP/370 Release 1 (program number 5665-295), announced June 7, 1983, was for MVS/SP Version 1, MVS/SE and OS/VS2 R3.8, and was optional, but MVS/Extended Architecture Data Facility Product (5665-284) was a corequisite for MVS/SP Version 2 (MVS/XA). In addition to enhancing data management facilities, DFP replaced free versions of the linkage editor and utilities. Modern MVS MVS has now evolved into z/OS; older MVS releases are no longer supported by IBM and, since 2007, only 64-bit z/OS releases are supported. z/OS supports running older 24-bit and 31-bit MVS applications alongside newer 64-bit applications. MVS releases up to 3.8j (24-bit, released in 1981) were freely available and it is now possible to run the MVS 3.8j release in mainframe emulators for free. MVS/370 MVS/370 is a generic term for all versions of the MVS operating system prior to MVS/XA. The System/370 architecture, at the time MVS was released, supported only 24-bit virtual addresses, so the MVS/370 operating system architecture is based on a 24-bit address. Because of this 24-bit address length, programs running under MVS/370 are each given 16 MB of contiguous virtual storage. MVS/XA MVS/XA, or Multiple Virtual Storage/Extended Architecture, was a version of MVS that supported the 370-XA architecture, which had a new I/O architecture and also expanded addresses from 24 bits to 31 bits, providing a 2 gigabyte addressable memory area. MVS/XA supported a 24-bit legacy addressing mode for older 24-bit applications (i.e. those that stored a 24-bit address in the lower 24 bits of a 32-bit word and utilized the upper 8 bits of that word for other purposes). MVS/ESA MVS/ESA: MVS Enterprise System Architecture. Versions of MVS, introduced as MVS/SP Version 3 in February 1988, then MVS/ESA SP Version 4 and MVS/ESA SP Version 5. Replaced by as OS/390 late 1995 and subsequently by z/OS. MVS/ESA OpenEdition: upgrade to Version 4 Release 3 of MVS/ESA announced February 1993 with support for POSIX and other standards. While the initial release only had National Institute of Standards and Technology (NIST) certification for Federal Information Processing Standard (FIPS) 151 compliance, subsequent releases were certified at higher levels and by other organizations, e.g. X/Open and its successor, The Open Group. It included about 1 million new lines of code, which provide an API shell, utilities, and an extended user interface. Works with a hierarchical file system provided by DFSMS (Data Facility System Managed Storage). The shell and utilities are based on Mortice Kerns' InterOpen products. Independent specialists estimate that it was over 80% open systems-compliant—more than most Unix systems. DCE2 support announced February 1994, and many application development tools in March 1995. From mid 1995, as all of the open features became a standard part of vanilla MVS/ESA SP Version 5 Release 1, IBM stopped distinguishing OpenEdition from the operating system. Under OS/390 V2R6 it became UNIX System Services, and has kept that name under z/OS. OS/390 In late 1995 IBM bundled MVS with several program products and changed the name from MVS/ESA to OS/390. z/OS The current level of MVS is marketed as z/OS. Closely related operating systems Japanese mainframe manufacturers Fujitsu and Hitachi both repeatedly and illegally obtained IBM's MVS source code and internal documentation in one of the 20th century's most famous cases of industrial espionage. Fujitsu relied heavily on IBM's code in its MSP mainframe operating system, and likewise Hitachi did the same for its VOS3 operating system. MSP and VOS3 were heavily marketed in Japan, where they still hold a substantial share of the mainframe installed base, but also to some degree in other countries, notably Australia. Even IBM's bugs and documentation misspellings were faithfully copied. IBM cooperated with the U.S. Federal Bureau of Investigation in a sting operation, reluctantly supplying Fujitsu and Hitachi with proprietary MVS and mainframe hardware technologies during the course of multi-year investigations culminating in the early 1980s—investigations which implicated senior company managers and even some Japanese government officials. Amdahl, however, was not involved in Fujitsu's theft of IBM's intellectual property. Any communications from Amdahl to Fujitsu were through "Amdahl Only Specifications" which were scrupulously cleansed of any IBM IP or any references to IBM's IP. Subsequent to the investigations, IBM reached multimillion-dollar settlements with both Fujitsu and Hitachi, collecting substantial fractions of both companies' profits for many years. Reliable reports indicate that the settlements exceeded US$500,000,000. The three companies have long since amicably agreed to many joint business ventures. For example, in 2000 IBM and Hitachi collaborated on developing the IBM z900 mainframe model. Because of this historical copying, MSP and VOS3 are properly classified as "forks" of MVS, and many third-party software vendors with MVS-compatible products were able to produce MSP- and VOS3-compatible versions with little or no modification. When IBM introduced its 64-bit z/Architecture mainframes in the year 2000, IBM also introduced the 64-bit z/OS operating system, the direct successor to OS/390 and MVS. Fujitsu and Hitachi opted not to license IBM's z/Architecture for their quasi-MVS operating systems and hardware systems, and so MSP and VOS3, while still nominally supported by their vendors, maintain most of MVS's 1980s architectural limitations to the present day. Since z/OS still supports MVS-era applications and technologies— z/OS still contains most of MVS's code, albeit greatly enhanced and improved over decades of evolution—applications (and operational procedures) running on MSP and VOS3 can move to z/OS much more easily than to other operating systems. See also Hercules a S/370, S/390, and zSeries emulator capable of running MVS Utility programs supplied with MVS (and successor) operating systems BatchPipes is a batch job processing utility designed for the MVS/ESA operating system, and all later incarnations—OS/390 and z/OS. Notes References Bob DuCharme: "The Operating Systems Handbook, Part 06: MVS" (available online here) External links IBM: z/OS V1R11.0 MVS Manuals IBM: z/OS V1R8.0 MVS manuals MVS: the operating system that keeps the world going MVS... a long history Functional structure of IBM virtual storage operating systems Part II: OS/VS2-2 concepts and philosophies by A. L. Scherr IBM mainframe operating systems 1974 software

Operating System (OS)

Firefox OS Firefox OS (project name: Boot to Gecko, also known as B2G) is a discontinued open-source operating system made for smartphones, tablet computers, smart TVs and dongles designed by Mozilla and external contributors. It is based on the rendering engine of the Firefox web browser, Gecko, and on the Linux kernel. It was first commercially released in 2013. Firefox OS was designed to provide a complete, community-based alternative operating system, for running web applications directly or those installed from an application marketplace. The applications use open standards and approaches such as JavaScript and HTML5, a robust privilege model, and open web APIs that can communicate directly with hardware, e.g. cellphone hardware. As such, Mozilla with Firefox OS competed with commercially developed operating systems such as Apple's iOS, Google's Android, Microsoft's Windows Phone, BlackBerry's BlackBerry 10, Samsung's/Linux Foundation's Tizen and Jolla's Sailfish OS. In December 2015, Mozilla announced it would stop development of new Firefox OS smartphones, and in September 2016 announced the end of development. Successors to Firefox OS include the discontinued B2G OS and Acadine Technologies' H5OS as well as KaiOS Technologies' KaiOS and Panasonic's My Home Screen. History Firefox OS was publicly demonstrated in February 2012, on Android-compatible smartphones. By December 16, 2014, fourteen operators in 28 countries throughout the world offered Firefox OS phones. On December 8, 2015, Mozilla announced that it would stop sales of Firefox OS smartphones through carriers. Mozilla later announced that Firefox OS smartphones would be discontinued by May 2016, as the development of "Firefox OS for smartphones" would cease after the release of version 2.6. Around the same time, it was reported that Acadine Technologies, a startup founded by Li Gong (former president of Mozilla Corporation) with various other former Mozilla staff among its employees, would take over the mission of developing carrier partnerships, for its own Firefox OS derivative H5OS. In January 2016 Mozilla announced that Firefox OS would power Panasonic's UHD TVs (as previously announced Firefox OS "would pivot to connected devices"). In September 2016 Mozilla announced that work on Firefox OS had ceased, and that all B2G-related code would be removed from mozilla-central. Project inception and roll-out Commencement of project On July 25, 2011, Andreas Gal, Director of Research at Mozilla Corporation, announced the "Boot to Gecko" Project (B2G) on the mozilla.dev.platform mailing list. The project proposal was to "pursue the goal of building a complete, standalone operating system for the open web" in order to "find the gaps that keep web developers from being able to build apps that are in every way the equals of native apps built for the iPhone, Android, and Windows Phone 7." The announcement identified these work areas: new web APIs to expose device and OS capabilities such as telephone and camera, a privilege model to safely expose these to web pages, applications to prove these capabilities, and low-level code to boot on an Android-compatible device. This led to much blog coverage. According to Ars Technica, "Mozilla says that B2G is motivated by a desire to demonstrate that the standards-based open Web has the potential to be a competitive alternative to the existing single-vendor application development stacks offered by the dominant mobile operating systems." In 2012, Andreas Gal expanded on Mozilla's aims. He characterized the current set of mobile operating systems as "walled gardens" and presented Firefox OS as more accessible: "We use completely open standards and there’s no proprietary software or technology involved." (That changed in 2014; see Digital rights management (DRM), below.) Gal also said that because the software stack is entirely HTML5, there are already a large number of established developers. This assumption is employed in Mozilla's WebAPI. These are intended W3C standards that attempt to bridge the capability gap that currently exists between native frameworks and web applications. The goal of these efforts is to enable developers to build applications using WebAPI which would then run in any standards compliant browser without the need to rewrite their application for each platform. Development history In July 2012, Boot to Gecko was rebranded as 'Firefox OS', after Mozilla's well-known desktop browser, Firefox, and screenshots began appearing in August 2012. In September 2012, analysts Strategy Analysts forecast that Firefox OS would account for 1% of the global smartphone market in 2013, its first year of commercial availability. In February 2013, Mozilla announced plans for its global commercial roll-out of Firefox OS. Mozilla announced at a press conference before the start of Mobile World Congress in Barcelona that the first wave of Firefox OS devices would be available to consumers in Brazil, Colombia, Hungary, Mexico, Montenegro, Poland, Serbia, Spain and Venezuela. Mozilla also announced that LG Electronics, ZTE, Huawei and TCL Corporation had committed to making Firefox OS devices. In December 2013, new features were added with the 1.2 release, including conference calling, silent SMS authentication for mobile billing, improved push notifications, and three state settings for Do Not Track. Async Pan and Zoom (APZ), included in version 1.3, should improve user interface responsiveness. Work was done to optimize Firefox OS to run a 128 MB platform with version 1.3T. A 128 MB device is out that seems to use that version but it may be unfinished. In 2015, Mozilla ported Firefox OS (an "experimental version") to MIPS32 to work in a sub-$100 tablet (that can also run Android 4.4 KitKat). Mozilla has worked on developing the OS for Smart Feature Phones. Firefox OS was discontinued in January 2017. Digital rights management (DRM) In 2014, Gal announced a change in course, writing that future versions of the Firefox browser would include DRM. Implementation of DRM in the Firefox browser began with version 38. In August 2015, attempts by Matchstick TV (based on Firefox OS) to add DRM caused the demise of Matchstick, a decision that Boing Boing called "suicide-by-DRM". Demonstrations At Mobile World Congress 2012, Mozilla and Telefónica announced that the Spanish telecommunications provider intended to deliver "open Web devices" in 2012, based on HTML5 and these APIs. Mozilla also announced support for the project from Adobe and Qualcomm, and that Deutsche Telekom’s Innovation Labs would join the project. Mozilla demonstrated a "sneak preview" of the software and apps running on Samsung Galaxy S II phones (replacing their usual Android operating system). In August 2012, a Nokia employee demonstrated the OS running on a Raspberry Pi. Firefox OS is compatible with a number of devices, including Otoro, PandaBoard, Emulator (ARM and x86), Desktop, Nexus S, Nexus S 4G, Samsung Galaxy S II, Galaxy Nexus and Nexus 4. A MIPS port was created by Imagination Technologies in March 2015. In December 2012, Mozilla rolled out another update and released Firefox OS Simulator 1.0, which can be downloaded as an add-on for Firefox. The latest version of Firefox OS Simulator, version 4.0, was released on July 3, 2013 and announced on July 11, 2013. Mozilla's planned US$25 Firefox smartphone displayed at MWC, is built by Spreadtrum. Mozilla has collaborated with four handset makers and five wireless carriers to provide five Firefox-powered smartphones in Europe and Latin America so far with cellphone launches being led by UK marketer John D. Bernard. In India, Mozilla planned a launching at $25 in partnership with Intex & Spice, but the price ended up being $33 (converted from 1,999 Rupees). Core technologies The initial development work involves three major software layers: Gonk – platform denomination for a combination of the Linux kernel and the HAL from Android Gecko – the web browser engine and application run-time services layer Gaia – an HTML5 layer and user-interface system Gonk Gonk consists of a Linux kernel and user-space hardware abstraction layer (HAL). The kernel and several user-space libraries are common open-source projects: Linux, libusb, BlueZ, etc. Some other parts of the HAL are shared with the Android project: GPS, camera, among others. Gonk is basically an extremely simple Linux distribution and is therefore from Gecko's perspective, simply a porting target of Gecko; there is a port of Gecko to Gonk, just like there is a port of Gecko to OS X, and a port of Gecko to Android. However, since the development team have full control over Gonk, the developers can fully expose all the features and interfaces required for comprehensive mobile platforms such as Gecko, but which aren't currently possible to access on other mobile OSes. For example, using Gonk, Gecko can obtain direct access to the full telephone stack and display framebuffer, but doesn't have this access on any other OS. Gecko Gecko is the web browser engine of Firefox OS. Gecko implements open standards for HTML, CSS, and JavaScript. Gecko includes a networking stack, graphics stack, layout engine, virtual machine (for JavaScript), and porting layers. Gaia Gaia is the user interface of Firefox OS and controls everything drawn to the screen. Gaia includes by default implementations of a lock screen, home screen, telephone dialer and contacts application, text-messaging application, camera application and gallery support, plus the classic phone apps: mail, calendar, calculator and marketplace. Gaia is written entirely in HTML, CSS, and JavaScript. It interfaces with the operating system through Open Web APIs, which are implemented by Gecko. Because it uses only standard web APIs, it can work on other OSes and other web browsers. Release history Forks Panasonic continues to develop the operating system for use in their Smart TVs, which run My Home Screen, powered by the Firefox OS. Acadine Technologies has derived their H5OS from Firefox OS as well. Li Gong, the founder of the company, had overseen the development of Firefox OS while serving as president of Mozilla Corporation. A fork called KaiOS has been used on a few feature phones, including Alcatel's OneTouch Go Flip (known as Cingular Flip 2 on AT&T), Reliance Jio's JioPhone (LYF F30C), and Intex's Turbo+ 4G. The system brings support for 4G LTE, Wi-Fi, GPS, and HTML5-based apps onto non-touch devices with an optimized user interface, less memory usage, and longer battery life. B2G OS B2G OS (Boot 2 Gecko) was a community-developed mobile operating system, and the successor to Firefox OS. It follows the Firefox OS goal of providing a complete, community-based alternative operating system, that runs software as web applications. Its mobile apps therefore use open web standards and programming languages such as JavaScript and HTML5, a robust privilege model, and open web APIs that can communicate directly with the device's hardware. It is now the basis of KaiOS which has (as of Jan 2019) over 17 percent of the Indian mobile phone market and is the third most popular phone OS. KaiOS is closed-source. History B2G OS was forked from Firefox OS following Mozilla's decision to discontinue support for their mobile operating system. The decision was made, according to Ari Jaaksi and David Bryant, in order to "evolve quickly and enable substantial new architectural changes in Gecko, Mozilla’s Platform Engineering organization needs to remove all B2G-related code from mozilla-central." , B2G OS is no longer maintained. Comparison with Android Firefox OS used the Linux kernel like Android does. Firefox OS used the Gecko engine on top of the Linux kernel to render the screen output. Apps were written using HTML5, CSS and JavaScript—all three being cooperative languages used in making internet webpages. In essence apps on Firefox OS were web apps and the OS could be thought of as a Web browser that stored content off-line. On the other hand, Android's apps are coded in Java using Android Studio. Android also enjoys greater maturity and support. Despite these differences, Firefox OS did feature all the essentials required to use a smartphone. Firefox launched its first official device in Germany in 2014, which was an Alcatel One Touch Fire. The device had a 3.5” HVGA screen, Cortex A5 processor, 256MB RAM and 512MB storage. As of December 2015, Mozilla had launched 12 smartphones across 24 countries. Criticisms Chris Ziegler of the technology website The Verge wrote that Firefox OS would take app distribution to the pre-iPhone era, requiring application developers to deal with multiple carriers and their app stores. At the Mobile World Congress, Mozilla's CEO Gary Kovacs said that Firefox OS has the advantage that users need not install an app to use it. Mozilla sought to make the most of this with the search functionality built into Firefox OS, a core feature of the platform. Janne Lindqvist, a mobile security researcher at the Rutgers University WINLAB, expressed concern about the discovery mechanism of a Web-based platform, but a Mozilla spokesperson stated that Mozilla required developers to "package downloadable apps in a zip file that has been cryptographically signed by the store from which it originated, assuring that it has been reviewed." In addition, "apps coming back from search are given only limited access to device programming interfaces and applications, unless the user grants permission for further access." Devices Officially and unofficially supported devices The structural similarities between Firefox OS and Android allow the Mozilla platform to run on a number of devices that ship with Android. While some ports of Firefox OS are hardly different from their original versions, others are heavily modified to fit the device in question. There are quite a few to note that are specifically made for Firefox OS as stated above. There are some that are designed for the developers themselves and others that are consumer-phones. There are also emulators for testing both apps and the OS itself on the desktop which are designed for both OS testing and the developers themselves. Firefox OS specific devices for developers: Geeksphone Keon Geeksphone Peak T2Mobile Flame ZTE Open ZTE Open C Firefox OS specific devices for consumers: Alcatel Onetouch FireC 4020D APC Paper Cherry Mobile Ace Intex Cloud FX KDDI Fx0 Spice Fire One MI FX1 Spice Fire One Mi-FX 2 Symphony GoFox F15 Zen 105 Firefox ZTE Open II Firefox OS has been ported to the following devices: HTC Explorer Huawei Ascend G510 Huawei Ascend Y300 Ingenic JZ4780 based devices (2015) Moto G Nexus 4 Nexus 5 Nexus 7 (2013) Samsung Galaxy S6 Edge+ Sony Xperia E Sony Xperia SP Sony Xperia T2 Ultra Sony Xperia Z3 See also H5OS KaiOS OpenFlint – open streaming technology for Firefox OS using the Matchstick dongle Stagefright (bug) – security bug fixed in Firefox OS 2.2, but mostly known to affect Android MeeGo Sailfish OS WebOS Comparison of mobile operating systems Comparison of Firefox OS devices References External links 2013 software ARM operating systems Discontinued operating systems Embedded Linux distributions Free mobile software Gecko-based software Mobile Linux Mozilla Smartphones Software that uses XUL X86 operating systems Linux distributions

Operating System (OS)

SpartaDOS X SpartaDOS X (or SpartaDOS 4.0) is a disk operating system for the Atari 8-bit family of computers that closely resembles MS-DOS. It was developed and sold by ICD, Inc. in 1987-1993, and many years later picked up by the third-party community SpartaDOS X Upgrade Project, which still maintains the software. History SpartaDOS X is a successor to SpartaDOS 1.0, 2.0 and 3.0 (also ICD products) and while it enjoys good level of backward compatibility with older versions, it is a completely new system, written from scratch. SpartaDOS X 4.0 was originally developed by Michael Gustafson in 1987-89, and shipped on 64k ROM cartridges by ICD, Inc. up to version 4.21. The cartridge contained an additional cartridge slot on itself, so that it was possible to plug-in another cartridge, such as ICD's R-Time 8 battery-backed clock, a language cartridge (Action!, MAC/65 etc.) or a game cartridge, and use it in conjunction with the DOS. In 1992 Atari Corp. dropped all the official support for their 8-bit computers, and so did ICD shortly after that. The rights for the 8-bit ICD inventory were purchased in November 1993 by Michael Hohman, officially as Fine Tooned Engineering. FTE released a slightly updated version 4.22 on 5 November 1995, and, after two or three years, disappeared together with all the items and rights it owned. Ten years later development of SpartaDOS X, then considered abandonware, was picked up by its enthusiasts, as SpartaDOS X Upgrade Project. It resulted in several unofficial revisions of the software, incorporating many of the utilities written since 1992, cleaning many identified problems and including numerous improvements. the published versions are: 4.31 (2005) 4.39RC (2006) 4.40 (a leaked-out beta, 2006) 4.41 (Feb. 2008) 4.42 (Dec. 2008) 4.43 (Apr. 2011) 4.44 (Jun. 2011) 4.45 (Nov. 2011) 4.46 (Jan. 2013) 4.47 (Feb. 2015) 4.48 (Jul. 2016) 4.49 (Apr. 2020) Characteristics General SpartaDOS X is a non-multitasking operating system intentionally modeled after and closely resembling MS-DOS in look and feel. It consists of the kernel, the system library, several types of drivers, the shell (called COMMAND.COM) and a number of utility programs. SpartaDOS X is written in 6502 machine language and fits into a 128k file-oriented ROM cartridge. Supported storage devices There is full support for Atari-type serial disk drives as well as for parallel hard drives, as long as they conform to Atari standards (i.e. as long as they use the "plug-and-play" Parallel Bus Interface (PBI) mechanism implemented in the ROM OS of the XL/XE computers). For those which do not, and for ramdisks and the like, up to four block-device drivers can be installed. Nonstandard hard disk interfaces are handled by specialized drivers. The maximum number of drives (or hard disk partitions) connected at the same time is 15 as of version 4.40 (9 in earlier versions). Kernel built-in functions The kernel allows to open files and directories in read-only, write-only, write-append and read-write modes. It also maintains environment variables, and programs may request files to be searched through directories specified in $PATH. The variables also control some settings for the DOS as well as for programs, for example the format of date and time to be displayed (the choice is between the "European" DD-MM-YY and 24-hour clock, and "American" MM-DD-YY and 12-hour clock). The file system drivers Thanks to some form of virtual filesystem, practically any filesystem can be directly accessed, if an appropriate filesystem driver exists and was loaded to the memory. Up to eight such drivers can be installed at a time. The main filesystem driver (fitting within less than 4.5 KB) can search directories (FFIRST/FNEXT), read/write files (FREAD/FWRITE), retrieve or change the current position within a file (FTELL/FSEEK), retrieve the file's length (FILELENG), delete files and directories (REMOVE/RMDIR), rename files and directories (RENAME/RENDIR), make directories (MKDIR), change attributes in files and directories (CHMOD), change current directory (CHDIR), retrieve path to current directory (GETCWD), collect information about the disk (GETDFREE), and make a binary file bootable (SETBOOT). It also maintains the queued buffer cache that can hold up to 16 sectors (8 KB) at a time. The SpartaDOS file system The proprietary file system format, called SpartaDOS FS (unrelated to and not compatible with MS-DOS FAT), offers full support for subdirectories, MS-DOS-like attributes (AHPS: Archived, Hidden, Protected, Subdirectory), modification date and time stamps, random access to data within a file, sparse files. The file naming convention is 8+3 (this scheme, inherited from CP/M, is normal on Atari). The directory structure is hierarchical, there are no other than practical limits in nesting directories. A directory can contain up to 1423 entries of files and other directories. The file system is 16-bit: a drive can contain up to 65,535 logical sectors (sector 0 does not exist on Atari disks). The logical sector size is 128 or 256 bytes in earlier versions, and 128, 256 and 512 bytes as of v. 4.40. This makes a maximum capacity of 16 MB per partition in earlier versions, and 32 MB as of v.4.40. A 4 GB per disk – by making sector clusters, up to 65,536 bytes per cluster – is theoretically possible, but not yet implemented. The DOS library The system library contains a binary loader supporting standard, address-dependent Atari binaries as well as SpartaDOS X address-independent ("relocatable") binary files. It also facilitates such tasks as error handling, parsing the command line, as well as managing memory, file and device resources etc. The library also contains a menu-driven disk formatter, that can be invoked at any time, not only from the DOS' Command Processor, but also from within an application program. The entire library occupies 24 KB of the cartridge (in three banks, 8 KB each) and can be switched off as necessary to release some memory. COMMAND.COM The SpartaDOS X default user interface is a command-line interpreter with the same name as the one used by MS-DOS: COMMAND.COM. The SpartaDOS X COMMAND.COM program is less than 4 KB and includes roughly 45 internal commands such as DIR, CD, DEL etc. I/O redirection uses "<<" and ">>" instead of "<" and ">" of UNIX and other systems (this is because the ">" sign is the SpartaDOS native path separator). Pseudo-pipelines are available as of SpartaDOS X version 4.42. Batch files can contain structured conditionals such as IF ... ELSE ... FI, GOTO, GOSUB, procedures, and loops. The environment variable $COMSPEC may point to an alternative command-line interpreter, to be loaded instead of COMMAND.COM. Commands, utility programs and optional extensions Additional utility, called RUNEXT, allows to associate data types with programs to be invoked automatically, when the user enters the name of the data file at the DOS prompt and hits the Return key. A program called MENU facilitates complex file management tasks and can serve as a replacement shell. Other utilities allow to change disk names, search disks for files, undelete them, install keyboard buffer, edit system files (CONFIG.SYS and AUTOEXEC.BAT) and so on. A port of ARC provides file compression facilities. Among the dedicated programs, which are not directly available on the cartridge and thus are not bundled with DOS itself, there are disk editors available as well as utilities to check and repair filesystem consistency. The following commands are supported by SpartaDOS X. APPEND ARC ATR ATTRIB BASIC BLOAD BOOT CAR CD CHDIR CHKDSK CHTD CHVOL CLR CLS COLD COMMAND COMP CON COPY CREDIR CWD DATE DEL DELDIR DELETE DELTREE DEV DF DIR DIRS DUMP ECHO ED ERASE FIND FMT FORMAT KEY LESS LOAD MAN MAP MD MDUMP MEM MENU MKDIR MORE PATH PAUSE PEEK POKE PROMPT PWD RD REN RENAME RENDIR RMDIR RS232 SAVE SET SETPATHS SIOSET SORTDIR SWAP TD TIME TYPE UNERASE VER VERIFY X Configuration At startup, a text file called CONFIG.SYS is read from the boot disk. The contents of the file decides, which memory the DOS will use to keep the bulk of its code and drivers (the choice is between the extended memory and two areas of the conventional 64K), how many files can be opened at a time, the size of the buffer cache and its location in the memory (same choices as for the DOS code), the default environment variables, and which drivers to load. Apart from the "main" one, there can be up to 9 alternative configuration files (or 19 as of v.4.45). The choice between them is offered at startup in a form of a menu. When no CONFIG.SYS file is present, the default one is loaded from the cartridge. The other default file that can be used for configuration is AUTOEXEC.BAT. It is a batch file that is run by the COMMAND.COM, when the COMMAND.COM is loaded for the first time. Requirements SpartaDOS X requires an Atari 8-bit (400, 800 or XL/XE models) computer equipped with at least 48 KB of conventional memory to run, or 64 KB to be truly usable (on a 48K machine there is too little memory left as to execute most programs). The recommended configuration, though, is at least 128 KB of RAM (64k conventional plus at least 64k extended). The DOS can use the extended memory to keep large portion of its code, buffer cache and internal structures thus releasing the conventional memory. The rest of the extended memory can be used for additional drivers or ramdisks. Relation to other DOS-es for Atari Unlike its predecessor, SpartaDOS 3.0, SpartaDOS X is not what is commonly referred to as a "DOS" in Atari 8-bit parlance. The Atari 8-bit Operating System consists of two main parts: the ROM-based "OS" and bootable "DOS". The common misconception about that division is that these respective parts correspond to BIOS and DOS on an IBM PC compatible machine. In reality the "OS" is responsible for communication not only with the block devices (like PC BIOS), but also for character devices, including file-oriented ones (like PC DOS). Consequently, all the file management functions are centralized in the "OS"-part, and the "DOS"-part is only one of its subordinated device drivers, that performs on a mass-storage media (like floppy disk). A "DOS" for Atari, then, typically consists of the aforementioned device driver (called FMS, "File Management System"), and an application program playing the role of the OS shell. This shell is typically called DUP, "Disk Utility Package". All the communication between the user programs (including the DUP) and FMS goes through the CIO ("Central Input/Output") residing in ROM. Such a design has some shortcomings, for example, no typical DOS is able to keep more than eight files opened at a time, because this is the limit imposed by the API of the ROM-based "OS". Now SpartaDOS X, even though it is registered in the ROM-based CIO as a device driver and (for backward compatibility) performs all typical DOS functions as requested that way, is in fact independent of the CIO. Instead, it has own "I/O centre" (known as "the kernel"), not related to the ROM-based OS, with own set of specifiers and drivers for both character devices (like CON: or COM:) and block devices. Under SpartaDOS X programs can perform all the I/O operations through the SpartaDOS kernel bypassing the Atari OS in ROM completely. Thanks to that it was possible to break many of its limitations: e.g. there can be as many as 16 files opened at a time. This also makes SpartaDOS X (unlike, for example, its predecessor SpartaDOS 3.2, or any other DOS for Atari) an operating system, not just another device driver with some sort of a shell. References Atari 8-bit family software Atari operating systems Disk operating systems 1988 software

Operating System (OS)

Usage share of operating systems The usage share of operating systems is the percentage of computing devices that run each operating system (OS) at any particular time. All such figures are necessarily estimates because data about operating system share is difficult to obtain. There are few reliable primary sources and no agreed methodologies for its collection. Operating systems are used in numerous device types, from embedded devices without a screen through to supercomputers. Most device types that people interact with access the web, so using web access statistics helps compare the usage share of operating systems across most device types, and also the usage share of operating systems used for the same types. Android, an operating system using the Linux kernel, is the world's most-used operating system when judged by web use. It has 41% of the global market, followed by Windows with 32%, Apple iOS with 16%, then Chrome OS at 1.1% also using the Linux kernel. These numbers do not include embedded devices or game consoles. For smartphones and other pocket-sized devices, Android leads with 73% market share, and Apple's iOS has 27%. For desktop and laptop computers, Windows is the most used at 75%, followed by Apple's macOS at 16%, and Linux-based operating systems, including Google's Chrome OS, at 5% (thereof "desktop Linux" at 2.35%). With tablets, Apple's iOS has 55% and Android has 45%. For the above devices, smartphones and other pocket-sized devices make up 55%, desktops and laptops 43%, and tablets 2.5%. Linux has completely dominated the supercomputer field since 2017, with 100% of the top 500 most powerful supercomputers in the world running a Linux distribution. Linux is also most used for (web) servers, and then most often Ubuntu used, the most common Linux distribution. Embedded devices are the most numerous type of device (with specific operating systems made for them), yet a high percentage are standalone or do not have a web browser, which makes their usage share difficult to measure. Hypothetically some specific operating system used in embedded devices is more popular than the ones mentioned above. Worldwide device shipments In May 2020, Gartner predicted a decline in all market segments for 2020 (from already declining market in 2019) due to COVID-19, predicting a decline by 13.6% for all devices, while "Work from Home Trend Saved PC Market from Collapse", with them only predicting to decline by 10.5% for PCs. However, in the end according to Gartner, PC shipments grew "10.7% in Fourth Quarter of 2020 and [...] reached 275 million units in 2020, a 4.8% increase from 2019 and the highest growth in ten years." Apple in 4th place for PCs had the largest growth in shipments for a company in Q4 of 31.3%, while "the fourth quarter of 2020 was another remarkable period of growth for Chromebooks, with shipments increasing around 200% year over year to reach 11.7 million units. In 2020, Chromebook shipments increased over 80% to total nearly 30 million units, largely due to demand from the North American education market." Chromebooks sold more than Apple's Macs worldwide. According to Gartner, the following is the worldwide device shipments (referring to wholesale) by operating system, which includes smartphones, tablets, laptops and PCs together. Shipments (to stores) do not mean sales to consumers (not necessarily in the year of shipment), therefore suggesting the numbers indicate popularity and/or usage could be misleading. Not only do smartphones sell in higher numbers than traditional PCs but also as a whole a lot more, by dollar value with the gap only projected to widen, to well over double. For 2015 (and earlier), Gartner reports for "the year, worldwide PC shipments declined for the fourth consecutive year, which started in 2012 with the launch of tablets" with an 8% decline in PC sales for 2015 (not including cumulative decline in sales over the previous years). Gartner includes Macs (running macOS) in PC sales numbers (but not e.g. iPads and Androids), and they individually had a slight increase in sales in 2015. On 28 May 2015, Google announced that there were 1.4 billion Android users and 1 billion Google play users active during that month. This changed to 2 billion monthly active users in May 2017. On 27 January 2016, Paul Thurrott summarized the operating system market, the day after Apple announced "one billion devices": Microsoft backed away from their goal of one billion Windows 10 devices in three years (or "by the middle of 2018") and reported on 26 September 2016 that Windows 10 was running on over 400 million devices, and in March 2019 on more than 800 million. By late 2016, Android had been explained to be "killing" Apple's iOS market share (i.e. its declining sales of smartphones, not just relatively but also by number of units, when the whole market is increasing) with As of 9 May 2019, the biggest smartphone companies (by market share) were Samsung, Huawei and Apple, respectively. Gartner's own press release said, "Apple continued its downward trend with a decline of 7.7 percent in the second quarter of 2016", which is their decline, based on absolute number of units, that underestimates the relative decline (with the market increasing), along with the misleading "1.7 percent [point]" decline. That point decline means an 11.6% relative decline (from 14.6% down to 12.9%). Although in units sold Apple is declining, they are almost the only vendor making any profit in the smartphone sector from hardware sales alone. In Q3 2016 for example, they captured 103.6% of the market profits. There are more mobile phone owners than toothbrush owners, with mobile phones the fastest growing technology in history. There are a billion more active mobile phones in the world than people (and many more than 10 billion sold so far with less than half still in use), explained by the fact that some people have more than one, such as an extra for work. All the phones have an operating system, but only a fraction of them are smartphones with an OS capable of running modern applications. Currently 3.1 billion smartphones and tablets are in use across the world (with tablets, a small fraction of the total, generally running the same operating systems, Android or iOS, the latter being more popular on tablets. In 2019, a variant of iOS called iPadOS built for iPad tablets was released). Tablet computers In 2015, eMarketer estimated at the beginning of the year that the tablet installed base would hit one billion for the first time (with China's use at 328 million, which Google Play doesn't serve or track, and the United States's use second at 156 million). At the end of the year, because of cheap tablets not counted by all analysts that goal was met (even excluding cumulative sales of previous years) as: This conflicts with statistics from IDC that say the tablet market contracted by 10% in 2015 with only Huawei, ranked fifth, with big gains, more than doubling their share; for fourth quarter 2015, the five biggest vendors were the same except that Amazon Fire tablets ranked third worldwide, new on the list, enabled by its not quite tripling of market share to 7.9%, with its Fire OS Android-derivative. Web clients The most recent data from various sources published during the last twelve months is summarized in the table below. All of these sources monitor a substantial number of web sites; statistics related to one web site only are excluded. Android currently ranks highest, above Windows (incl. Xbox console) systems. Windows Phone accounted for 0.51% of the web usage, before it was discontinued. Considering all personal computing devices, Microsoft Windows is well below 50% usage share on every continent, e.g. at 31% in the US and in many countries lower, e.g. China, and in India at 19% and Windows' lowest share globally was 30% in July 2021, and 28% in the US. On weekends iOS tops Windows in the US (and on some weekends Android is also more popular than Windows), and iOS alone got even with Windows for the month of November 2019, in large part due to the spike in sales for the 5 days around Thanksgiving. That season iOS had a 46% lead over Windows and, along with Android, contributed to a higher market share of mobile devices over desktops for 6 weeks. Before iOS became the most popular operating system in any independent country, it was most popular in Guam, an unincorporated territory of the United States, for four consecutive quarters in 2017-18, although Android is now the most popular there. iOS has been the highest ranked OS in Jersey (a British Crown dependency in Europe) for years, by a wide margin, and iOS was also highest ranked in Falkland Islands, a British Overseas Territory, for one quarter in 2019, before being overtaken by Android in the following quarter. iOS is competitive with Windows in Sweden, where some days it is more used. The designation of an "Unknown" operating system is strangely high in a few countries such as Madagascar where it was at 32.44% (no longer near as high). This may be due to the fact that StatCounter uses browser detection to get OS statistics, and there the most common browsers are not often used. The version breakdown for browsers in Madagascar shows "Other" at 34.9%, and Opera Mini 4.4 is the most popular known browser at 22.1% (plus e.g. 3.34% for Opera 7.6). However browser statistics without version-breakdown has Opera at 48.11% with the "Other" category very small. In China, Android got to be the highest ranked operating system in July 2016 (Windows has occasionally topped it since then, while since April 2016 it or all non-mobile operating systems haven't outranked mobile operating systems, meaning Android plus iOS). In the Asian continent as a whole, Android has been ranked highest since February 2016 and Android alone has the majority share, because of a large majority in all the most populous countries of the continent, up to 84% in Bangladesh, where it has had over 70% share for over four years. Since August 2015, Android is ranked first, at 48.36% in May 2016, in the African continent when it took a big jump ahead of Windows 7, and thereby Africa joined Asia as a mobile-majority continent. China is no longer a desktop-majority country, joining India, which has a mobile-majority of 71%, confirming Asia's significant mobile-majority. Online usage of Linux kernel derivatives (Android + Chrome OS + other Linux) exceeds that of Windows. This has been true since some time between January and April 2016, according to W3Counter and StatCounter. However, even before that, the figure for all Unix-like OSes, including those from Apple, was higher than that for Windows. Notes Desktop and laptop computers Windows is still the dominant desktop OS, but the dominance varies by region and it has gradually lost market share to other desktop operating systems (not just to mobile) with the slide very noticeable in the US, where macOS usage has more than quadrupled from Jan. 2009 to Dec. 2020 to 30.62% (i.e. in Christmas month; and 34.72% in April 2020 in the middle of COVID-19, and iOS was more popular overall that year; globally Windows lost to Android that year, as for the two years prior), with Windows down to 61.136% and Chrome OS at 5.46%, plus traditional Linux at 1.73%. There is little openly published information on the device shipments of desktop and laptop computers. Gartner publishes estimates, but the way the estimates are calculated is not openly published. Another source of market share of various operating systems is StatCounter basing its estimate on web use (although this may not be very accurate). Also, sales may overstate usage. Most computers are sold with a pre-installed operating system, with some users replacing that OS with a different one due to personal preference, or installing another OS alongside it and using both. Conversely, sales underestimate usage by not counting unauthorized copies. For example, in 2009, approximately 80% of software sold in China consisted of illegitimate copies. In 2007, the statistics from an automated update of IE7 for registered Windows computers differed with the observed web browser share, leading one writer to estimate that 25–35% of all Windows XP installations were unlicensed. The usage share of Microsoft's (then latest operating system) Windows 10 has slowly increased since July/August 2016, reaching around 27.15% (of all Windows versions, not all desktop or all operating systems) in December 2016. It eventually reached 79.79% on 5 October 2021, the same day on which its successor Windows 11 was released. Web analysis shows significant variation in different parts of the world. For example, macOS use varies a lot by region, in North America claims 16.82% (17.52% in the US) whereas in Asia it is only 4.4%. In the United States usage of Windows XP has dropped to 0.38% (of all Windows versions), and its global average to 0.59%, while in Africa it is still at 2.71%, and it still has double-digit share in at least one country. The 2019 Stack Overflow developer survey provides no detail about particular versions of Windows. The desktop operating system share among those identifying as professional developers was: Windows: 45.3% macOS: 29.2% Linux: 25.3% BSD/Unix: 0.1% Microsoft data on Windows usage In June 2016, Microsoft claimed Windows 10 had half the market share of all Windows installations in the US and UK, as quoted by BetaNews: ===Desktop computer games=== The digital video game distribution platform Steam publishes a monthly "Hardware & Software Survey", with the statistics below: These figures, as reported by Steam, do not include SteamOS statistics. Mobile devices Smartphones By Q1 2018, mobile operating systems on smartphones included Google's dominant Android (and variants) and Apple's iOS which combined had an almost 100% market share. Smartphone penetration vs. desktop use differs substantially by country. Some countries, like Russia, still have smartphone use as low as 22.35% (as a fraction of all web use), but in most western countries, smartphone use is close to 50% of all web use. This doesn't mean that only half of the population has a smartphone, could mean almost all have, just that other platforms have about equal use. Smartphone usage share in developing countries is much higher in Bangladesh, for example, Android smartphones had up to 84% and currently 70% share, and in Mali smartphones had over 90% (up to 95%) share for almost two years. (A section below has more information on regional trends on the move to smartphones.) There is a clear correlation between the GDP per capita of a country and that country's respective smartphone OS market share, with users in the richest countries being much more likely to choose Apple's iPhone, with Google's Android being predominant elsewhere. Note Table is only showing mobile OS market share not the overall market share. Wikimedia Foundation statistics consider tablets as part of the mobile OS market share. Tablet computers Tablet computers, or simply tablets, became a significant OS market share category starting with Apple's iPad. In Q1 2018, iOS had 65.03% market share and Android had 34.58% market share. Windows tablets may not get classified as such by some analysts, and thus barely register; e.g. 2-in-1 PCs may get classified as "desktops", not tablets. Since 2016, in South America (and Cuba in North America), Android tablets have gained majority, and in Asia in 2017 Android was slightly more popular than the iPad, which was at 49.05% usage share in October 2015. In Africa, Android tablets are much more popular while elsewhere the iPad has a safe margin. , Android has made steady gains to becoming the most popular tablet operating system: that is the trend in many countries, having already gained the majority in large countries (India at 63.25%, and in Indonesia at 62.22%) and in the African continent with Android at 62.22% (first to gain Android majority in late 2014), with steady gains from 20.98% in August 2012 (Egypt at 62.37%, Zimbabwe at 62.04%), and South America at 51.09% in July 2015. (Peru at 52.96%). Asia is at 46%. In Nepal, Android gained majority lead in November 2014 but lost it down to 41.35% with iOS at 56.51%. In Taiwan, as of October 2016, Android after having gained a confident majority, has been on a losing streak. China is a major exception to Android gaining market share in Asia (there Android phablets are much more popular than Android tablets, while similar devices get classified as smartphones) where the iPad/iOS is at 82.84% in March 2015. Crossover to smartphones having majority share According to StatCounter web use statistics (a proxy for all use), smartphones are more popular than desktop computers globally (and Android in particular more popular than Windows). Including tablets with mobiles/smartphones, as they also run so-called mobile operating systems, even in the United States (and most countries) are mobiles including tablets more popular than other (older originally made for desktops) operating systems (such as Windows and macOS). Windows in the US (at 33.42%) has only 8% head-start (2.55-percentage points) over iOS only; with Android, that mobile operating system and iOS have 52.14% majority. Alternatively, Apple, with iOS plus their non-mobile macOS (9.33%) has 20% more share (6.7-percentage points more) than Microsoft's Windows in the country where both companies were built. Although desktop computers are still popular in many countries (while overall down to 44.9% in the first quarter of 2017), smartphones are more popular even in many developed countries. A few countries on all continents are desktop-minority with Android more popular than Windows; many, e.g. Poland in Europe, and about half of the countries in South America, and many in North America, e.g. Guatemala, Honduras, Haiti; up to most countries in Asia and Africa with smartphone-majority because of Android, Poland and Turkey in Europe highest with 57.68% and 62.33%, respectively. In Ireland, smartphone use at 45.55% outnumbers desktop use and mobile as a whole gains majority when including the tablet share at 9.12%. Spain was also slightly desktop-minority. As of July 2019, Sweden had been desktop-minority for eight weeks in a row. The range of measured mobile web use varies a lot by country, and a StatCounter press release recognizes "India amongst world leaders in use of mobile to surf the internet" (of the big countries) where the share is around (or over) 80% and desktop is at 19.56%, with Russia trailing with 17.8% mobile use (and desktop the rest). Smartphones (discounting tablets), first gained majority in December 2016 (desktop-majority was lost the month before), and it wasn't a Christmas-time fluke, as while close to majority after smartphone majority happened again in March 2017. In the week of 7–13 November 2016, smartphones alone (without tablets) overtook desktop for the first time, albeit for a short period. Examples of mobile-majority countries include Paraguay in South America, Poland in Europe and Turkey and most of Asia and Africa. Some of the world is still desktop-majority, with for example the United States at 54.89% (but not on all days). However, in some territories of the United States, such as Puerto Rico, desktop is significantly under majority, with Windows just under 25%, overtaken by Android. On 22 October 2016 (and subsequent weekends), mobile showed majority. Since 27 October, the desktop hasn't had a majority, including on weekdays. Smartphones alone have showed majority since 23 December to the end of the year, with the share topping at 58.22% on Christmas Day. To the "mobile"-majority share of smartphones, tablets could be added giving a 63.22% majority. While an unusually high top, a similar high also occurred on Monday 17 April 2017, with the smartphone share slightly lower and tablet share slightly higher, combining to 62.88%. Formerly, according to a StatCounter press release, the world has turned desktop-minority; , at about 49% desktop use for that month, but mobile wasn't ranked higher, tablet share had to be added to it to exceed desktop share. For the Christmas season (i.e. temporarily, while desktop-minority remains and smartphone-majority on weekends), the last two weeks in December 2016, Australia (and Oceania in general) was desktop-minority for the first time for an extended period, i.e. every day from 23 December. In South America, smartphones alone took majority from desktops on Christmas Day, but for a full-week-average, desktop is still at least at 58%. The UK desktop-minority dropped down to 44.02% on Christmas Day and for the eight days to the end of the year. Ireland joined some other European countries with smartphone-majority, for three days after Christmas, topping that day at 55.39%. In the US, desktop-minority happened for three days on and around Christmas (while a longer four-day stretch happened in November, and happens frequently on weekends). According to StatCounter web use statistics (a proxy for all use), in the week from 7–13 November 2016, "mobile" (meaning smartphones) alone (without tablets) overtook desktop, for the first time, with them highest ranked at 52.13% (on 27 November 2016) or up to 49.02% for a full week. Mobile-majority applies to countries such as Paraguay in South America, Poland in Europe and Turkey; and the continents Asia and Africa. Large regions of the rest of the world are still desktop-majority, while on some days, the United States, (and North America as a whole) isn't; the US is desktop-minority up to four days in a row, and up to a five-day average. Other examples, of desktop-minority on some days, include the UK, Ireland, Australia (and Oceania as a whole); in fact, at least one country on every continent has turned desktop-minority (for at least a month). On 22 October 2016 (and subsequent weekends), mobile has shown majority. Previously, according to a StatCounter press release, the world has turned desktop-minority; , at about 49% desktop use for that month, with desktop-minority stretching up to an 18-weeks/4-months period from 28 June to 31 October 2016, while whole of July, August or September 2016, showed desktop-majority (and many other long sub-periods in the long stretch showed desktop-minority; similarly only Fridays, Saturdays and Sundays are desktop-minority). The biggest continents, Asia and Africa, have shown vast mobile-majority for long time (any day of the week), as well as several individual countries elsewhere have also turned mobile-majority: Poland, Albania (and Turkey) in Europe and Paraguay and Bolivia in South America. According to StatCounter's web use statistics, Saturday 28 May 2016, was the day when smartphones ("mobile" at StatCounter, that now counts tablets separately) became a most used platform, ranking first, at 47.27%, above desktops. The next day, desktops slightly outnumbered "mobile" (unless counting tablets: some analysts count tablets with smartphones or separately while others with desktops even when most tablets are iPad or Android, not Windows devices). Since Sunday 27 March 2016, the first day the world dipped to desktop-minority, it has happened almost every week, and by week of 11–17 July 2016, the world was desktop-minority, followed by the next week, and thereon also for a three-week period. The trend is still stronger on weekends, with e.g. 17 July 2016 showed desktop at 44.67%, "mobile" at 49.5% plus tablets at 5.7%. Recent weekly data shows a downward trend for desktops. According to StatCounter web use statistics (a proxy for overall use), on weekends desktops worldwide lose about 5 percent points, e.g. down to 51.46% on 15 August 2015, with the loss in (relative) web use going to mobile (and also a minuscule increase for tablets), mostly because Windows 7, ranked 1st on workdays, declines in web use, with it shifting to Android and lesser degree to iOS. Two continents, have already crossed over to mobile-majority (because of Android), based on StatCounters web use statistics. In June 2015, Asia became the first continent where mobile overtook desktop (followed by Africa in August; while Nigeria had mobile majority in October 2011, because of Symbian that later had 51% share, then Series 40 dominating, followed by Android as dominating operating system) and as far back as October 2014, they had reported this trend on a large scale in a press release: "Mobile usage has already overtaken desktop in several countries including India, South Africa and Saudi Arabia". In India, desktop went from majority, in July 2012, down to 32%. In Bangladesh desktop went from majority, in May 2013, down to 17%, with Android alone now accounting for majority web use. Only a few African countries were still desktop-majority and many have a large mobile majority including Ethiopia and Kenya, where mobile usage is over 72%. The popularity of mobile use worldwide has been driven by the huge popularity increase of Android in Asian countries, where Android is the highest ranked operating system statistically in virtually every south-east Asian country, while it also ranks most popular in almost every African country. Poland has been desktop-minority since April 2015, because of Android being vastly more popular there, and other European countries, such as Albania (and Turkey), have also crossed over. The South America continent is somewhat far from losing desktop-majority, but Paraguay had lost it . Android and mobile browsing in general has also become hugely popular in all other continents where desktop has a large desktop base and the trend to mobile is not as clear as a fraction of the total web use. While some analysts count tablets with desktops (as some of them run Windows), others count them with mobile phones (as the vast majority of tablets run so-called mobile operating systems, such as Android or iOS on the iPad). iPad has a clear lead globally, but has clearly lost the majority to Android in South America, and a number of Eastern European countries such as Poland; lost virtually all African countries and has lost the majority twice in Asia, but gained the majority back (while many individual countries, e.g. India and most of the middle East have clear Android majority on tablets). Android on tablets is thus second most popular after the iPad. In March 2015, for the first time in the US the number of mobile-only adult internet users exceeded the number of desktop-only internet users with 11.6% of the digital population only using mobile compared to 10.6% only using desktop; this also means the majority, 78%, use both desktop and mobile to access the internet. A few smaller countries in North America, such as Haiti (because of Android) have gone mobile majority (mobile went to up to 72.35%, and is at 64.43% in February 2016). Revenue The region with the largest Android usage also has the largest mobile revenue. Public servers on the Internet Internet based servers' market share can be measured with statistical surveys of publicly accessible servers, such as web servers, mail servers or DNS servers on the Internet: the operating systems powering such servers are found by inspecting raw response messages. This method gives insight only into market share of operating systems that are publicly accessible on the Internet. There will be differences in the result depending on how the sample is done and observations weighted. Usually the surveys are not based on a random sample of all IP addresses, domain names, hosts or organisations, but on servers found by some other method. Additionally, many domains and IP addresses may be served by one host and some domains may be served by several hosts or by one host with several IP addresses. Note Revenue comparisons often include "operating system software, other bundled software" and are not appropriate for usage comparison as the Linux operating system costs nothing (including "other bundled software"), except if optionally using commercial distributions such as Red Hat Enterprise Linux (in that case, cost of software for all software bundled with hardware has to be known for all operating systems involved, and subtracted). In cases where no-cost Linux is used, such comparisons underestimate Linux server popularity and overestimate other proprietary operating systems such as Unix and Windows. Mainframes Mainframes are larger and more powerful than servers, but not supercomputers. They are used to process large sets of data, for example enterprise resource planning or credit card transactions. The most common operating system for mainframes is IBM's z/OS. Operating systems for IBM Z generation hardware include IBM's proprietary z/OS, Linux on IBM Z, z/TPF, z/VSE and z/VM. Gartner reported on 23 December 2008, that Linux on System z was used on approximately 28% of the "customer z base" and that they expected this to increase to over 50% in the following five years. Of Linux on IBM Z, Red Hat and Micro Focus compete to sell RHEL and SLES respectively: Prior to 2006, Novell claimed a market share of 85% or more for SUSE Linux Enterprise Server. Red Hat has since claimed 18.4% in 2007 and 37% in 2008. Gartner reported at the end of 2008 that Novell's SUSE Linux Enterprise Server had an 80% share of mainframe Linux. Decline Like today's trend of mobile devices from personal computers, in 1984 for the first time estimated sales of desktop computers ($11.6 billion) exceeded mainframe computers ($11.4 billion). IBM received the vast majority of mainframe revenue. From 1991 to 1996, AT&T Corporation briefly owned NCR, one of the major original mainframe producers. During the same period, companies found that servers based on microcomputer designs could be deployed at a fraction of the acquisition price and offer local users much greater control over their own systems given the IT policies and practices at that time. Terminals used for interacting with mainframe systems were gradually replaced by personal computers. Consequently, demand plummeted and new mainframe installations were restricted mainly to financial services and government. In the early 1990s, there was a rough consensus among industry analysts that the mainframe was a dying market as mainframe platforms were increasingly replaced by personal computer networks. In 2012, NASA powered down its last mainframe, an IBM System z9. However, IBM's successor to the z9, the z10, led a New York Times reporter to state four years earlier that "mainframe technology—hardware, software and services—remains a large and lucrative business for IBM, and mainframes are still the back-office engines behind the world's financial markets and much of global commerce". , while mainframe technology represented less than 3% of IBM's revenues, it "continue[d] to play an outsized role in Big Blue's results". Supercomputers The TOP500 project lists and ranks the 500 fastest supercomputers for which benchmark results are submitted. Since the early 1990s, the field of supercomputers has been dominated by Unix or Unix-like operating systems, and starting in 2017, every top 500 fastest supercomputer uses Linux as its supercomputer operating system. The last supercomputer to rank #1 while using an operating system other than Linux was ASCI White, which ran AIX. It held the title from November 2000 to November 2001, and was decommissioned in 2006. Then in June 2017, two AIX computers held rank 493 and 494, the last non-Linux systems before they dropped off the list. Historically all kinds of Unix operating systems dominated, and in the end ultimately Linux remains. Market share by category See also Comparison of operating systems List of operating systems Timeline of operating systems Usage share of web browsers Mobile OS market share Notes References Usage share of operating systems Operating systems

Operating System (OS)

ReactOS ReactOS is a free and open-source operating system for amd64/i686 personal computers intended to be binary-compatible with computer programs and device drivers made for Windows Server 2003 and later versions of Windows. ReactOS has been noted as a potential open-source drop-in replacement for Windows and for its information on undocumented Windows APIs. ReactOS has been in development since 1996. , it is still considered feature-incomplete alpha software, and is therefore recommended by the developers only for evaluation and testing purposes. However, many Windows applications are currently working, such as Adobe Reader 9.3, GIMP 2.6, and LibreOffice 5.4. ReactOS is primarily written in C, with some elements, such as ReactOS File Explorer, written in C++. The project partially implements Windows API functionality and has been ported to the AMD64 processor architecture. ReactOS, as part of the FOSS ecosystem, re-uses and collaborates with many other FOSS projects, most notably the Wine project, which presents a Windows compatibility layer for Unix-like operating systems. History Early development Around 1996, a group of free and open-source software developers started a project called FreeWin95 to implement a clone of Windows 95. The project stalled in discussions of the design of the system. While FreeWin95 had started out with high expectations, there still had not been any builds released to the public by the end of 1997. As a result, the project members, led by coordinator Jason Filby, joined together to revive the project. The revived project sought to duplicate the functionality of Windows NT. In creating the new project, a new name, ReactOS, was chosen. The project began development in February 1998 by creating the basis for a new NT kernel and basic drivers. The name ReactOS was coined during an IRC chat. While the term "OS" stood for operating system, the term "react" referred to the group's dissatisfaction with – and reaction to – Microsoft's monopolistic position. In 2002, the ReactOS Foundation was established in Moscow with Maxim Osowski and Aleksey Bragin as executive officers and Vladimir Bragin, Saveliy Tretiakov and Alexey Ivanov on the board of directors. In 2015, the foundation was liquidated. Internal audit In order to avoid copyright prosecution, ReactOS had to be expressly completely distinct and non-derivative from Windows, a goal that needed very careful work. A claim was made on 17 January 2006 by developer Hartmut Birr on the ReactOS developers mailing list (ros-dev) that ReactOS contained code derived from disassembling Microsoft Windows. The code that Birr disputed involved the function BadStack in syscall.S, as well as other unspecified items. Comparing this function to disassembled binaries from Windows XP, Birr argued that the BadStack function was simply copy-pasted from Windows XP, given that they were identical. Alex Ionescu, the author of the code, asserted that while the Windows XP binary in question was indeed disassembled and studied, the code was not merely copy-pasted, but reimplemented; the reason why the functions were identical, Ionescu claimed, was because there was only one possible way to implement the function. On 27 January 2006, the developers responsible for maintaining the ReactOS code repository disabled access after a meeting was held to discuss the allegations. When approached by NewsForge, Microsoft declined to comment on the incident. Since ReactOS is a free and open-source software development project, the claim triggered a negative reaction from the free software community; in particular, Wine barred several inactive developers from providing contributions and formal high level cooperation between the two projects remained difficult . Contributions from several active ReactOS developers have been accepted post-audit, and low level cooperation for bug fixes has been still occurring. In a statement on its website, ReactOS cited differing legal definitions of what constitutes clean-room reverse engineering as a cause for the conflict. To avoid potential litigation, companies sometimes enact a policy where reimplementation based on disassembled code must be written by someone other than the person having disassembled and examined the original code. ReactOS clarified its Intellectual Property Policy Statement requirements on clean room reverse engineering to avoid potential infringement of United States law. An internal source code audit was conducted to ensure that only clean room reverse engineering was used, and all developers were made to sign an agreement committing them to comply with the project's policies on reverse engineering. Contributors to its development were not affected by these events and all access to the software development tools was restored shortly afterward. In September 2007, with the audit nearing completion, the audit status was removed from the ReactOS homepage. Though the audit was completed, specific details were not made public, as it was only an internal effort to ensure compliance with the project's own policies. Much of the assembly code that was allegedly copied has also been replaced as a natural progression in ReactOS development, by the developers having reimplemented the functionality in C for portability reasons. Also, the 2004 leaked Windows source code was not seen as legal risk for ReactOS, as the trade secret was considered indefensible in court due to broad spread. Axel Rietschin, who is a kernel engineer at Microsoft, claimed that he recognized some specific bits in the ReactOS kernel that are unlikely to result from a clean room reimplementation. He suggests that the project took source code from the Windows Research Kernel, which was licensed to universities and has been leaked multiple times. Internal data structures and variable names have the exact same name in both ReactOS and the research kernel. Google Summer of Code participation Starting in 2006, the ReactOS project participated in several Google Summers of Code. For example, in the GSoC 2011, ReactOS mentored a student project which integrated lwIP into the network stack. ReactOS has to date participated six times in GSoC: 2006, 2011, 2016, 2017, 2018 and 2019. Lobbying for support in Russia Between 2007 and 2015, Russian ReactOS contributors representing the ReactOS Foundation made efforts at lobbying the Russian federal government. , these efforts have not yielded government support for ReactOS, and the Russia-based ReactOS Foundation has been dissolved since November 2015. In 2007, then State Duma member and nationalist hardliner Viktor Alksnis met with project coordinator Aleksey Bragin, who gave a presentation and demonstration of the project, showing ReactOS running with Total Commander and Mozilla Firefox. In 2011, a demonstration was given to then president Dmitry Medvedev during a visit to a high school in Verhnerusskoe, Stavropol, attended by one of the development team members. On 31 July 2012, Vladimir Putin was also given a demonstration during his visit as President of Russia to Seliger Youth Forum, attended by Marat Karatov, one of the development team members. On 1 April 2015, Bragin attended an expert meeting of the Russian Ministry of Communications on reducing Russia's dependency from proprietary software imports. Its minutes name the "creation of an open source operating system based on ReactOS for PCs, laptops and other mobile devices", as well as the "creation of an open source operating system for servers based on ReactOS", placing it second among three named proposals. Funding campaigns On 1 May 2012, a €30,000 funding campaign was started to finance additional development projects. At the end of the year, approximately 50% of the funding goal was achieved and it was decided to continue the funding campaign without deadlines. The money went to ReactOS Deutschland e. V.. As the tax law in Germany for this form of a registered voluntary association (Eingetragener Verein) makes it problematic to pay developers directly; indirect possibilities like stipends were evaluated. Thorium Core Cloud Desktop project When ReactOS was awarded as Project of the Month on SourceForge on June 2013, a crowdfunding campaign on Kickstarter was announced in an interview with the project's coordinator, Aleksey Bragin. On 23 December 2013 the announced project was revealed as a Kickstarter campaign with the goal of US$120,000 was started. The Thorium Core Cloud Desktop dubbed cloud computing service would use ReactOS as core and could allow the use of Windows compatible applications from mobile devices (like smartphones, tablets), workstations, or any other connected device. On 21 February 2014, fundraising ended short of the target amount, with $48,965 of $120,000 raised, resulting in no transferred money. ReactOS Community Edition In April 2014, the ReactOS project announced an Indiegogo campaign to launch ReactOS Community Edition, a version of ReactOS based on the 0.4 release. The flexible funding campaign had a goal of US$50,000 with additional stretch goals beyond that. Development of ReactOS Community Edition would be community-centric, with ReactOS users voting and funding to decide which software and hardware drivers the project will aim to support. On 1 June 2014, the flexible crowdfunding campaign on Indiegogo ended, raising $25,141 for the development of the community edition, and the voting process to support hardware and software was started shortly thereafter. ReactOS Hackfest The ReactOS project organized a hackfest from 7 to 12 August 2015, in the German city of Aachen. The Hackfest resulted in many features being added to ReactOS. The second hackfest was organized by the ReactOS project from 14 to 18 August 2017, in the German city of Cologne. The third and fourth hackfests were organized by the ReactOS project from 16 to 21 August 2018 and from 15 to 20 August 2019 in Berlin respectively. Greentea OS fork Greentea OS first appeared at ReactOS forums in 2016 and was warmly welcomed in the community at first, however starting with March 2017 any references to ReactOS were systematically removed from the project repositories while still being a ReactOS fork code-wise, which gave it a bad reputation in ReactOS community. Finally on 24 August 2018 most of Greentea OS repositories on GitHub were recreated from scratch without inclusion of any ReactOS code, so it became a separate project. Release history Features Programs ReactOS Explorer (File Explorer) ReactOS Applications Manager Accessories Calculator Command Prompt Notepad Paint WordPad Magnifier On-Screen Keyboard Remote Desktop Connection Multimedia Player (Media Player) Sound Recorder Volume Control Character Map Clipboard Viewer FontSub Keyboard Layout Switcher ReactX Diagnostic (DxDiag) Registry Editor SnapShot Task Manager Administrative Tools Device Manager Event Viewer Service Manager (Windows service) System Configuration (MSConfig) Games Solitaire (Microsoft Solitaire) Spider Solitaire (Microsoft Spider Solitaire) WineMine (Microsoft Minesweeper) Commands The following is a non-exhaustive list of commands that are supported by the ReactOS Command Prompt. ? alias assoc at attrib beep cacls call cat cd chdir chcp choice clip cls color comp copy ctty date dbgprint del delete delay dir dirs doskey echo echos echoerr echoserr endlocal eventcreate erase exit find for free fsutil goto help history hostname if label memory md mkdir mklink mode more move path pause popd prompt pushd rd rmdir reg rem ren rename replace sc schtasks screen set setlocal shift shutdown sort start taskkill tee time timeout timer title touch tree type uptime ver verify vol whoami xcopy Development ReactOS core development ReactOS is primarily written in C, with some elements, such as ReactOS Explorer and the sound stack, written in C++. The project compiles using both MinGW and Microsoft Visual Studio, and contributes to the development of the build systems used through the submission of patches to its components. The developers aim to make the kernel and usermode application programming interface (API) more compatible with Windows NT version 5.2 (Windows Server 2003) and to add support for more applications and hardware, with plans to target newer versions of Windows as development matures. DirectX support is undertaken through ReactX, an in-house implementation. 2D and OpenGL 3D hardware-accelerated rendering is done natively, while other drawing functionality such as Direct3D is redirected to OpenGL as a stopgap solution, mostly using Wine's code such as WineD3D. The development progress is influenced by the size of the development team and the level of experience among them. As an estimate of the effort required to implement Windows 7, Microsoft employed 1,000 or so developers, organized into 25 teams, with each team averaging 40 developers. , in the ReactOS entry in Ohloh, the page followed through the "Very large, active development team" link lists 33 developers who have contributed over a 12-month period and a cumulative total of 104 present and former users who have contributed code to the project via Apache Subversion since its inception. In his presentation at Hackmeeting 2009 in Milan, ReactOS developer Michele C. noted that most of the developers learn about Windows architecture while working on ReactOS and have no prior knowledge. While ReactOS targets currently mainly the x86/AMD64 PC platform, an effort to port to the ARM architecture was at one point "under way", while it did not produce much functionality and was abandoned along with a port to PowerPC, that is no longer actively maintained. Support for the Xbox and the NEC PC-9800, a variant IA-32 architecture, was added through the use of an architecture-specific HAL. Improved 64-bit support for ReactOS is "being worked on", however, development seems to be going slowly. Collaboration and reuse While ReactOS has the aim to build a Windows-compatible kernel as open-source software, much of the surrounding required functionality to create a complete OS is already available in the greater open-source ecosystem. When available and possible, ReactOS therefore builds on and collaborates with already existing open-source projects. Conversely, projects like Wine, and formerly Captive NTFS and Longene re-use the open-source ReactOS code-base as well. Hardware driver stack On the hardware driver side, for instance the UniATA project provides Serial ATA drivers for ReactOS. The project has also experimented with using the FullFAT library in its rewrite of its FAT Installable File System. ReactOS makes use of the USB stack from Haiku both as a reference and as a foundation for its USB support. Mesa 3D provides OpenGL rendering. Networking ReactOS's network stack is built on the TCP portion of OSKit's port of the network stack in FreeBSD, along with an internally developed implementation for packet-oriented protocols like IP. Later, lwIP was integrated into the ReactOS network stack. Windows network services like LSASS, SAM, NETLOGON, and print spooling are already available as open-source alternative by the Samba/Samba TNG project. A fork of rdesktop is used as an implementation of a client software for Microsoft's proprietary Remote Desktop Protocol. Wine cooperation The ReactOS and the Wine projects share the goal to run binary Windows software natively and can therefore share many dependencies and development. ReactOS uses portions of the Wine project so that it can benefit from Wine's progress in implementing the Win32 API. While Wine's NTDLL, USER32, KERNEL32, GDI32, and ADVAPI32 components cannot be used directly by ReactOS due to architectural differences, code snippets of them and other parts can be shared between both projects. The kernel is developed by ReactOS separately as Wine relies here on existing Unix-like kernels. Separately, the experimental Arwinss branch was created as an alternative means to improve USER32 and GDI32 support through an alternative implementation of the Win32 API. Whereas ReactOS's original Win32 subsystem was closely modeled after its equivalent in Windows, Arwinss combines the architecture of that subsystem with the corresponding implementation in Wine. To this end, Arwinss uses Wine's GDI32 and USER32 libraries with few changes to take fuller advantage of Wine's existing software compatibility. Arwinss also allows the user to optionally use a remote X server instead of a local display. Other The Tango Desktop Project initiative provides open-source design guidelines and resources (as icons) for applications on desktop environments. FreeType is an open-source software development library, used to render text on to bitmaps and provides support for other font-related operations. The KernelEx project is a Windows-API extension and compatibility layer project, which provides open-source implementations of some Windows-APIs. Other contributing projects are MinGW, SYSLINUX, adns, ICU, GraphApp, Ext2, GNU FreeFont, DejaVu fonts, and Liberation fonts. Forks Forks based on ReactOS are occasionally created: Ekush OS (2004) ReactOS Server (2008-2013) OpenROS (2013) FusionOS (2013) ReactOS NG (2015) – aiming for compatibility with Windows 8 Greentea OS (2016-2018) – aiming for accelerated and simplified development Reception Various people have acknowledged ReactOS and the implications of having a viable open-source drop-in replacement for Windows. A 2004 article and interview of the German weekly magazine Der Spiegel describes ReactOS as directed at Windows users who want to renounce use of proprietary commercial software without having to switch to Linux. DistroWatch, a Linux distribution's monitoring Web site, also lists ReactOS and describes it as "a free and open-source operating system based on the best design principles found in the Windows NT architecture." In his column for Free Software Magazine, David Sugar noted in 2006 that ReactOS would allow the use of applications depending on older versions of Windows whose APIs have been deprecated. He also recognized its potential to expand the total deployed base of free software, and as a resource for developers wanting to know undocumented Windows APIs in the course of writing portable applications. PC Magazine columnist John C. Dvorak remarked in 2008 that the Windows NT architecture had remained largely unchanged, making it an ideal candidate for cloning, and believed that ReactOS could be "a bigger threat than Linux to Microsoft's dominance". In response to Dvorak's column, ZDNet technology journalist Dana Blankenhorn noted in 2008 that a lack of corporate sponsors and partners had rendered the project harmless to Microsoft. Echoing this, Thom Holwerda of OSNews in 2009 categorized ReactOS under a family of hobby operating systems maintained only by small groups of developers working in their spare time, lacking the financial support of more mainstream operating systems and the legacy of formerly mainstream ones such as RISC OS. In October 2015, a Network World review of ReactOS v0.3.17 noted "It's just like running Windows 2000" and praised the application package manager, a feature the original Windows is missing. Jesse Smith from DistroWatch Weekly reviewed ReactOS v0.4.9, and noted that ReactOS "ultimately had a similar problem: limited hardware support" and is not yet a stable operating system. Awards The ReactOS Project won on the annual Seliger Youth Forum "The Best Presentation" award with 100,000 Russian rubles (~US$2700) in 2011, attended by Alexander Rechitskiy, one of the development team members. ReactOS was a featured project on SourceForge for the weeks beginning on 27 February 2012, 25 April 2013, and several others. It was Project of the Month on SourceForge for June 2013 and February 2019. See also Binary-code compatibility coLinux, a project allowing Microsoft Windows and the Linux kernel to run simultaneously in parallel on the same machine FreeDOS, a clone of MS-DOS Longene, a hybrid operating system kernel intended to be binary-compatible with both the Microsoft Windows and Linux ecosystems NDISwrapper, a re-creation of Windows NT kernel parts inside the Linux Kernel to allow the use of Windows drivers in Linux Wine, a compatibility layer that runs Microsoft Windows applications on Unix-like operating systems List of alternative shells for Windows Timelines of: Intel / Microsoft / Microsoft Windows / other operating systems (List) Comparison of operating systems Notes References External links 1998 software Alpha software Articles containing video clips Free software operating systems Free software programmed in C Free software programmed in C++ Live CD Operating system distributions bootable from read-only media Software derived from or incorporating Wine Upcoming software Window-based operating systems X86-64 operating systems IA-32 operating systems Works involved in plagiarism controversies

Operating System (OS)

UNICOS UNICOS is a range of Unix and after it Linux operating system (OS) variants developed by Cray for its supercomputers. UNICOS is the successor of the Cray Operating System (COS). It provides network clustering and source code compatibility layers for some other Unixes. UNICOS was originally introduced in 1985 with the Cray-2 system and later ported to other Cray models. The original UNICOS was based on UNIX System V Release 2, and had many Berkeley Software Distribution (BSD) features (e.g., computer networking and file system enhancements) added to it. Development CX-OS was the original name given to what is now UNICOS. This was a prototype system which ran on a Cray X-MP in 1984 before the Cray-2 port. It was used to demonstrate the feasibility of using Unix on a supercomputer system, before Cray-2 hardware was available. The operating system revamp was part of a larger movement inside Cray Research to modernize their corporate software: including rewriting their most important Fortran compiler (cft to cft77) in a higher-level language (Pascal) with more modern optimizations and vectorizations. As a migration path for existing COS customers wishing to transition to UNICOS, a Guest Operating System (GOS) capability was introduced into COS. The only guest OS that was ever supported was UNICOS. A COS batch job would be submitted to start up UNICOS, which would then run as a subsystem under COS, using a subset of the systems CPUs, memory, and peripheral devices. The UNICOS that ran under GOS was exactly the same as when it ran stand-alone: the difference was that the kernel would make certain low-level hardware requests through the COS GOS hook, rather than directly to the hardware. One of the sites that ran very early versions of UNICOS was Bell Labs, where Unix pioneers including Dennis Ritchie ported parts of their Eighth Edition Unix (including STREAMS input/output (I/O)) to UNICOS. They also experimented with a guest facility within UNICOS, allowing the stand-alone version of the OS to host itself. Releases Cray released several different OSs under the name UNICOS, including: UNICOS: the original Cray Unix, based on System V. Used on the Cray-1, Cray-2, X-MP, Y-MP, C90, etc. UNICOS MAX: a Mach-based microkernel used on the T3D's processing elements, together with UNICOS on the host Y-MP or C90 system. UNICOS/mk: a serverized version of UNICOS using the Chorus microkernel to make a distributed operating system. Used on the T3E. This was the last Cray OS really based on UNICOS sources, as the following products were based on different sources and simply used the "UNICOS" name. UNICOS/mp: not derived from UNICOS, but based on IRIX 6.5. Used on the X1. UNICOS/lc: not derived from UNICOS, but based on SUSE Linux. Used on the XT3, XT4 and XT5. UNICOS/lc 1.x comprises a combination of the compute elements run the Catamount microkernel (which itself is based on Cougaar) the service elements run SUSE Linux Cray Linux Environment (CLE): from release 2.1 onward, UNICOS/lc is now called Cray Linux Environment the compute elements run Compute Node Linux (CNL) (which is a customized Linux kernel) the service elements run SUSE Linux Enterprise Server See also Scientific Linux, a Linux distribution by Fermilab and CERN Rocks Cluster Distribution, a Linux distribution for supercomputers References Cray software Microkernel-based operating systems Microkernels Supercomputer operating systems UNIX System V Unix distributions Linux distributions 1984 software

Operating System (OS)

Comparison of operating system kernels A kernel is the most fundamental component of a computer operating system. A comparison of system kernels can provide insight into the design and architectural choices made by the developers of particular operating systems. Comparison criteria The following tables compare general and technical information for a number of widely used and currently available operating system kernels. Please see the individual products' articles for further information. Even though there are a large number and variety of available Linux distributions, all of these kernels are grouped under a single entry in these tables, due to the differences among them being of the patch level. See comparison of Linux distributions for a detailed comparison. Linux distributions that have highly modified kernels — for example, real-time computing kernels — should be listed separately. There are also a wide variety of minor BSD operating systems, many of which can be found at comparison of BSD operating systems. The tables specifically do not include subjective viewpoints on the merits of each kernel or operating system. For this kind of information, please see operating system advocacy. Feature overview The major contemporary general-purpose kernels are shown in comparison. Only an overview of the technical features is detailed. Transport protocol support In-kernel security In-kernel virtualization In-kernel server support Binary format support A comparison of OS support for different binary formats (executables): File system support Physical file systems: Networked file system support Supported CPU instruction sets and microarchitectures Supported GPU processors Supported kernel execution environment This table indicates, for each kernel, what operating systems' executable images and device drivers can be run by that kernel. Supported cipher algorithms This may be usable on some situations like file system encrypting. Supported compression algorithms This may be usable on some situations like compression file system. Supported message digest algorithms Supported Bluetooth protocols See also Comparison of open source operating systems Comparison of Linux distributions Comparison of BSD operating systems Comparison of Microsoft Windows versions List of operating systems Comparison of file systems Comparison of operating systems Operating system advocacy Footnotes Kernels Computing platforms Operating system kernels

Operating System (OS)

Solus (operating system) Solus (previously known as Evolve OS) is an independently developed operating system for the x86-64 architecture based on the Linux kernel and a choice of the homegrown Budgie desktop environment, GNOME, MATE or KDE Plasma as the desktop environment. Its package manager, eopkg, is based on the PiSi package management system from Pardus Linux, and it has a semi-rolling release model, with new package updates landing in the stable repository every Friday. The developers of Solus have stated that Solus is intended exclusively for use on personal computers and will not include software that is only useful in enterprise or server environments. History On September 20, 2015, Ikey Doherty announced that "Solus 1.0 will be codenamed Shannon, after the River Shannon in Ireland", indicating that "codenames for releases will continue this theme, using Irish rivers." In July 2016, Solus announced the intention to discard the concept of fixed point releases and to embrace a rolling release model. In January 2017, Doherty announced that Solus will adopt Flatpak to reassemble third party applications. In August, Doherty announced that Solus also will adopt "Snaps" (next to Flatpak). On June 13 the same year, it was announced that the developer team had been expanded with Stefan Ric, and Ikey Doherty – previously working for Intel on Clear Linux OS – started working full-time on Solus. On November 2, 2018, technology website Phoronix published an open letter from original founder Ikey Doherty confirming that he was stepping back from the project, assigning "any and all intellectual, naming and branding rights relating to the ownership of Solus" to the development team "with immediate and permanent effect, acknowledging them as the official owners and leadership of the project." On January 1, 2022, experience lead Josh Strobl announced his resignation from Solus, after 6 years of involvement with the project. Releases and reception Point releases Solus 1.0 "Shannon" was released December 27, 2015. Jessie Smith reviewed the release as part of a feature story in DistroWatch Weekly, a weekly opinion column and summary of events from the distribution world. While he "ran into a number of minor annoyances" such as "Solus panicking and shutting itself down", he concluded that "Solus 1.0 represents a decent start". Solus 1.1 was released February 2, 2016. HecticGeek blogger Gayan has described Solus 1.1 as a "well optimized operating system", praising significantly faster boot and shutdown times than Ubuntu 15.10. Due to several usability issues encountered, he recommended to wait another year before trying it out again. Solus 1.2 was released on June 20, 2016. Michael Huff has described Solus in his review 'Finding Solace in Solus Linux' as a unique and original project for "those who’ve been reluctant to travel the Linux galaxy". Solus 1.2.0.5 was released on September 7, 2016. Michael Huff, a programmer and data analyst, wrote in his second review of Solus in Freedom Penguin that "we finally have the power and ease-of-use of a Mac in a Linux distribution" and "that the only people who need to use Solus are those who value their happiness in computing", praising the operating system as only one of few independent projects assured of "a tight cult following with the potential for mass appeal." Solus 1.2.1 was released on October 19, 2016. This is the last fixed point release of Solus and all future releases will be based on the snapshot model (the OS is now following the rolling-release model). Rolling releases Solus is considered a curated rolling release. It is a rolling release in the sense that once installed, end-users are guaranteed to continuously receive security and software updates for their Solus installation. Updates become available every Friday. Solus 2017.01.01.0, a snapshot following the recently adopted rolling release model, was released on January 1, 2017. Solus 2017.04.18.0, was released on April 18, 2017. Solus 3 was released on August 15, 2017. Solus 3.9999 (Solus 3 ISO Refresh) was released on September 20, 2018. Solus 4.0 "Fortitude" was released on March 17, 2019. Announcing the release, Solus Experience Lead, Joshua Strobl stated that Solus 4.0 delivered "a brand new Budgie experience, updated sets of default applications and theming, and hardware enablement". Solus 4.1 was released on January 25, 2020. Solus 4.2 was released on February 3, 2021. Solus 4.3 was released on July 11, 2021. Editions Solus is currently available in four editions: Budgie flagship edition, a "feature-rich, luxurious desktop using the most modern technologies"; GNOME edition, running the GNOME desktop environment, "a contemporary desktop experience"; MATE edition using the MATE desktop environment, a "traditional desktop for advanced users and older hardware"; KDE Plasma edition, "a sophisticated desktop experience for the tinkerers". Budgie Ikey Doherty stated that, regarding Budgie, he "wanted something that was a modern take on the traditional desktop, but not too traditional", aiming to keep a balance between aesthetics and functionality. Core team Technical lead: Beatrice T. Meyers [DataDrake] Global Maintainers: Friedrich von Gellhorn [Girtablulu], Joey Riches [joebonrichie], and Pierre-Yves [kyrios] Features Curated rolling release Solus brings updates to its users by means of a curated rolling release model. It is a rolling release in the sense that once installed, end-users are guaranteed to continuously receive security and software updates for their Solus installation without having to worry that their operating system will reach end-of-life. The latter is typically the case with fixed point releases of operating systems such as Fedora and Ubuntu but also Microsoft Windows. Marius Nestor at Softpedia has argued that all operating systems should use the rolling release model in order to decrease development and maintenance workload for developers and to make the latest technologies available for end users as soon as these are ready for the market. Compared to other rolling release operating systems such as Arch Linux - which provides bleeding edge software, i.e. software so new that there is a relatively high risk that software breakages might occur and render the system partially or completely unusable, Solus takes a slightly more conservative approach to software updates, hence the term curated rolling release. In contrast to Arch, Software on Solus is commonly referred to as cutting edge, typically excluding beta software, and is released after a short period of testing (in the unstable software repository) to end users in order to provide a safer, more stable and reliable update experience. By prioritizing usability (curated rolling release) over availability (pure rolling release), Solus intends to make the operating system accessible to a wider target market than Arch Linux, which is mainly aimed at more advanced users possessing in-depth technical knowledge about their system. Solus is also a curated rolling release in allowing its users to participate in the actual curation process, broadly conceived as the process by which software is selected, maintained and updated (on the server side in the software repositories of the operating system as well as on the client side on the end users computer system). More specifically, and contrary to other operating systems with various 'enforced update mechanisms', a Solus user has the freedom to choose what gets updated and when updates are applied (if at all), except for mandatory security updates. Software availability Solus comes pre-installed with a wide range of software that includes the latest Firefox, Thunderbird, LibreOffice, Transmission and GNOME MPV. Additional software that is not installed by default can be downloaded using the included Software Center. Wireless chips and modems are supported through optional non-free firmware packages. Package management is done through eopkg. Michael Huff has quoted project founder and lead developer Ikey Doherty that Solus will not be defined by its package manager. In a previous interview with Gavin Thomas from Gadget Daily on February 8, 2016, Doherty stated that as an end user the goal is to actually not interact with the package manager, sharply outlining the project's direction in terms of user experience. According to Doherty, the goal is "to actually get rid of it, so the user doesn’t even know about it." In Solus, the package manager is not intended to be used as a tool to deploy but to build software, distinguishing it from less beginner-friendly practices on other Linux-based operating systems. Software developed by Solus Budgie desktop environment: a GTK 3 desktop that tightly integrates with the GNOME software stack, employing the underlying technology. Starting with version 11, it was announced that Budgie will no longer be written in GTK, and the GNOME software stack will be fully replaced, due to unsolvable disagreements with the GNOME team. Raven: a sidebar interface that serves as an applet panel, notifications center and houses the desktop customization settings. Budgie Menu: a quick category and search-based application launcher. Budgie-wm: the window manager of the Budgie Desktop. eopkg: (Evolve OS Package) a fork of the PiSi package manager. ypkg: a tool to convert the build process into a packaging operation. ferryd: the binary repository manager for Solus. Software Center: a graphical frontend to install software in Solus. Brisk Menu: a menu co-written with the Ubuntu MATE development team, featured in Solus MATE. Security In July 2015, Solus announced integration of Clear Linux patches to deprecate insecure SSL ciphers, responding to a community post on Google+ by Arjan van de Ven. In response to security issues experienced by the Linux Mint project in late February 2016, Solus introduced improvements by providing a global Solus GPG key on its download section. Joshua Strobl, Communications Manager at Solus, announced the separation of official and community mirrors on the download page with official mirrors "to be regularly audited and updated" and "daily integrity checks against every ISO mirror" to be performed. Within its software center, Solus contains a wide variety of dedicated security software ranging from encryption software such as VeraCrypt to anonymization tools such as Tor. Solus integrates AppArmor instead of SELinux for restricting programs' capabilities. Popularity Because of user privacy, the Solus project doesn't track users so there isn't a direct and reliable way to measure popularity. As of July 2021, the DistroWatch website, which records the frequency of page clicks on its own site, ranked Solus 13th in the 6-month page hit rankings, 6th among the most popular rolling release distributions. and achieved an average reader-supplied review score of 8.42 out of 10. Critical reception Solus 3 was named one of the best Linux distributions of 2017 by OMG! Ubuntu! Matt Hartley praised Solus in his overview of the best Linux-based operating systems of 2017, as "Perhaps the most interesting distro in recent years...taking a unique approach to a logical user workflow, package management and how they work with the community. I see them doing great things in the future." In the more mainstream media Jason Evangelho covered Solus a few times for Forbes magazine. Solus received a lot of appraisal from Evangelho in his articles covering PC gaming and tech industry, most notable regarding gaming on Solus Linux and about the 4.0 release. References Notes: External links Solus on OpenSourceFeed gallery Free software operating systems Linux X86-64 Linux distributions Rolling Release Linux distributions Linux distributions

Operating System (OS)

Windows 3.1x Windows 3.1 is a series of 16-bit operating environments produced by Microsoft for use on personal computers, released on April 6, 1992. The series began with Windows 3.1, which was first sold during April 1992 as a successor to Windows 3.0. Subsequent versions were released between 1992 and 1993, notably Windows 3.11, until the series was superseded by the Windows 9x series starting in 1995 with Windows 95. During its lifespan, Windows 3.1 introduced several enhancements to the still MS-DOS-based platform, including improved system stability, expanded support for multimedia, TrueType fonts, and workgroup networking. On December 31, 2001, Microsoft declared Windows 3.1 obsolete and stopped providing support and updates for the system. However, OEM licensing for Windows for Workgroups 3.11 on embedded systems continued to be available until November 1, 2008. Editions Windows 3.1 Windows 3.1, released on April 6, 1992, introduced a TrueType font system (and a set of highly legible fonts), which effectively made Windows a viable desktop publishing platform for the first time. Similar functionality was available for Windows 3.0 through Adobe Type Manager (ATM) font system from Adobe. Windows 3.1 was designed to have backward compatibility with older Windows platforms. As with Windows 3.0, version 3.1 had File Manager and Program Manager, but unlike all previous versions, Windows 3.1 cannot run in real mode. It included Minesweeper as a replacement for Reversi (though Reversi was still included in some copies). Improvements over Windows 3.0 Windows 3.1 dropped real mode support and required a minimum of a 286 PC with 1 MB of RAM to run. The effect of this was to increase system stability over the crash-prone Windows 3.0. Some older features were removed, like CGA graphics support (although Windows 3.0's CGA driver still worked on 3.1) and compatibility with real-mode Windows 2.x applications. Windows 3.1 can run in Standard mode if installed with the VGA display driver. When installed with high resolution/high color driver, it only operates in 386 Enhanced Mode. TrueType font support was added, providing scalable fonts to Windows applications, without having to resort to using a third-party font technology such as Adobe Type Manager. Windows 3.1 included the following fonts: Arial, Courier New, and Times New Roman, in regular, bold, italic, and bold-italic versions, as well as Symbol (a collection of scalable symbols). TrueType fonts could be scaled to any size and rotated, depending on the calling application. In 386 Enhanced Mode, windowed DOS applications gained the ability for users to manipulate menus and other objects in the program using the Windows mouse pointer, provided that a DOS application supported mice. A few DOS applications, such as late releases of Microsoft Word, could access Windows Clipboard. Windows' own drivers could not work directly with DOS applications; hardware such as mice required a DOS driver to be loaded before starting Windows. Icons could be dragged and dropped for the first time, in addition to having a more detailed appearance. A file could be dragged onto the Print Manager icon and the file would be printed by the current printer, assuming it was associated with an application capable of printing, such as a word processor. Alternatively, the file could be dragged out of File Manager and dropped onto an application icon or window for processing. While Windows 3.0 was limited to 16 MB maximum memory, Windows 3.1 can access a theoretical 4 GB in 386 Enhanced Mode. The actual practical ceiling is 256 MB. However, no single process can use more than 16 MB. File Manager was significantly improved over Windows 3.0. Multimedia support was enhanced over what was available in Windows 3.0 with Multimedia Extensions and available to all Windows 3.1 users. Windows 3.1 was available via 720 KB, 1.2 MB, and 1.44 MB floppy distributions. It was also the first version of Windows to be distributed on CD-ROM – although this was more common for Windows for Workgroups 3.11. Installed size on the hard disk was between 10 MB and 15 MB. 32-bit disk access (386 Enhanced Mode only) brought improved performance by using a 32-bit protected mode driver instead of the 16-bit BIOS functions (which necessitate Windows temporarily dropping out of protected mode). Windows 3.1's calendar uses the filename extension. Windows 3.1 also introduced the Windows Registry, a centralized database that can store configuration information and settings for various operating systems components and applications. Windows 3.1 was the first version that could also launch Windows programs via Command.com. Windows 3.1 for Central and Eastern Europe A special version named Windows 3.1 for Central and Eastern Europe was released that allowed use of Cyrillic and had fonts with diacritic marks characteristic of Central and Eastern European languages. Microsoft introduced its own code page (Windows-1250) and supported its use in violation of many countries' ISO standards (e.g., the official Polish codepage is ISO-8859-2, which was ignored by Microsoft but is supported by contemporary Internet Explorer versions). Similarly, Microsoft also released Windows 3.1J with support for Japanese, which shipped 1.46 million copies in its first year on the market (1993) in Japan. Modular Windows Modular Windows is a special version of Windows 3.1, designed to run on Tandy Video Information System. Windows 3.11 Windows 3.11 was released on November 8, 1993. It did not add many feature improvements over Windows 3.1; it primarily contained bug fixes, but was considered a significant improvement because of those fixes, contributing to the operating system's popularity. Microsoft replaced all retail versions of Windows 3.1 with Windows 3.11 and provided a free upgrade to anyone who currently owned Windows 3.1. Windows 3.2 On November 22, 1993, Microsoft released a Simplified Chinese version of Windows for the Chinese market. In 1994, an update was released, which identified itself as Windows 3.2. Thus, Windows 3.2 is an updated version of the Simplified Chinese version of Windows 3.1. The update was limited to this language version, as it only fixed issues related to the complex input system for the Simplified Chinese language. Windows 3.2 was generally sold by computer manufacturers with a ten-disk version of MS-DOS that also had Simplified Chinese characters in basic output and some translated utilities. Windows for Workgroups Windows for Workgroups is an extension that allowed users to share their resources and to request those of others without a centralized authentication server. It used SMB protocol over NetBIOS. Windows for Workgroups 3.1 Windows for Workgroups 3.1 (originally codenamed Winball and later Sparta), released in October 1992, is an extended version of Windows 3.1 that features native networking support. It comes with SMB file sharing support via NetBIOS-based NBF and IPX network transport protocols and introduces the Hearts card game and VSHARE.386, a VxD version of SHARE.EXE (a terminate-and-stay-resident program). Windows for Workgroups 3.11 Windows for Workgroups 3.11 (originally codenamed Snowball) was released on August 11, 1993, and shipped in November 1993, by Microsoft. It supported 32-bit file access, full 32-bit network redirectors, and VCACHE.386 file cache, shared between them. WFW 3.11 dropped standard mode support and requires a 386 machine to run. A Winsock package was required to support TCP/IP networking in Windows 3.x. Usually third-party packages were used, but in August 1994, Microsoft released an add-on package (codenamed Wolverine) that provided TCP/IP support in Windows for Workgroups 3.11. Wolverine was a 32-bit stack (accessible from 16-bit Windows applications via WinSock Thunk), which gave it superior performance to most of the third-party TCP/IP Windows stacks available. However, it was only compatible with Windows for Workgroups 3.11, and lacked support for dial-up. Wolverine stack was an early version of the TCP/IP stack that would later ship with Windows 95, and provided an early testbed for the 16-to-32-bit compatibility layer that was crucial to Windows 95's success. Following the release of MS-DOS 6.22 in 1994, WFW 3.11 largely replaced Windows 3.1 for OEM installations on new PCs due to its improved capabilities and greater stability. Windows 95 The immediate successor to Windows 3.1, Windows 95, was released to manufacturing on August 15, 1995, and generally to retail on August 24, 1995. Windows 95 merged Microsoft's formerly separate MS-DOS and Microsoft Windows products; it was no longer necessary, as in Windows 3.1, to manually start Windows from the MS-DOS command line on each boot cycle. Windows 95 featured significant improvements over its predecessor, most notably in the graphical user interface (GUI) and in its simplified plug-and-play features. There were also major changes made to the core components of the operating system, such as moving from a mainly cooperatively multitasked 16-bit architecture to a 32-bit preemptive multitasking architecture, at least when running only 32-bit protected mode applications. Add-ons Video for Windows Video for Windows was first introduced in November 1992 as a reaction to Apple Computer's QuickTime technology which added digital video to Macintosh. Costing around $200, the software included editing and encoding programs for use with video input boards. A runtime version for viewing videos only was also made available. Originally released as a free add-on to Windows 3.1 and Windows 3.11, it then became an integral component of Windows 95 and later. Like QuickTime there were three components in Video for Windows. The technology introduced a file format designed to store digital video, Audio Video Interleave (AVI). The technology provided an application programming interface that allowed Windows software developers to add the ability to play or manipulate digital video to their own applications. Lastly, it included a suite of software for playing and manipulating digital video. Windows for Pen Computing Windows for Pen Computing was a series of Microsoft-produced add-ons for Microsoft Windows versions in the mid-1990s with additional tools for tablet PCs. Windows for Pen Computing (also known as Pen Windows and W4PC) was developed as Microsoft's pen computing response to PenPoint OS by GO Corporation. Windows for Pen Computing was rendered obsolete by Tablet PC support for Windows XP Tablet PC Edition in 2002. Win32s Windows 3.1x was given limited compatibility with the then-new 32-bit Windows API used by Windows NT by another add-on package, Win32s. There was a rumor that Microsoft did not want to increase any mainstream Windows 3.1x version to something like "Windows 3.2" because it could be confused with the Win32 API or otherwise distract consumers from upgrading to a "real 32-bit OS", though Windows NT 3.1 and 3.5 were both 32-bit operating systems that looked similar in appearance. A game called FreeCell was included for testing the new Win32s functions. WinG To entice game developers to move from DOS to Windows, Microsoft provided a first attempt at high-speed graphics and animation capabilities for Windows 3.1x, introduced in September 1994. Windows' GDI capabilities were originally designed with static images in mind, allowing only for write-only graphics calls. WinG provided a device-independent interface to graphics and printer hardware, and allowed programs to have both read and write capabilities to the WinGDC (WinG device context). Applications Windows 3.1x introduced new possibilities for applications, especially multimedia applications. During this era, Microsoft developed a new range of software that was implemented on this operating environment, called Microsoft Home, Microsoft Bob being one of the programs. As the first versions of Windows to enjoy major commercial success and software support, Windows 3.1 and WFW 3.11 quickly replaced DOS as the platform for application software on PC compatibles. Multimedia software (especially games) proliferated, although many games continued to run on DOS until Windows 95. Program Manager Program Manager was included in all versions of Windows from version 3.0 until Windows XP Service Pack 1. A non-operable icon library named progman.exe is included in Windows XP Service Pack 2, and the file was removed entirely from Windows Vista. Internet Explorer Internet Explorer 2 through Internet Explorer 5 were released for Windows 3.1. Promotion and reception Microsoft began a television advertising campaign for the first time on March 1, 1992. The advertisements, developed by Ogilvy & Mather, were designed to introduce a broader audience to Windows. Windows 3.1 was shipped worldwide on April 6, 1992, and reached three million sales two months later. The year of Windows 3.1's release was successful for Microsoft, which was named the "Most Innovative Company Operating in the U.S." by Fortune magazine, while Windows became the most widely used GUI-based operating environment. DR-DOS compatibility The installer to the beta release used code that checked whether it was running on Microsoft-licensed DOS or another DOS operating system (such as DR-DOS). The code ran several functional tests that succeeded on MS-DOS and IBM PC DOS, but resulted in a technical support message on competing operating systems. If the system was not MS-DOS, the installer would fail. Digital Research, who owned DR-DOS, released a patch within weeks to allow the installer to continue. Microsoft disabled, but did not remove, this warning message for the final release of Windows 3.1. When Caldera bought DR-DOS from Novell, they brought a lawsuit against Microsoft over the AARD code, which was later settled with Microsoft paying $280 million. Legacy Windows 3.x was superseded by the release of Windows 95 in August 1995. Microsoft officially dropped support for all 16-bit versions of Windows on November 1, 2008. Windows 3.1 found a niche market as an embedded operating system after becoming obsolete in the PC world. As of November 2008, both Virgin Atlantic and Qantas employed it for some of the onboard entertainment systems on long-distance jets. It also sees continued use as an embedded OS in retail cash tills. On July 9, 2008, it was announced that Windows for Workgroups 3.11 for the embedded devices channel would no longer be made available for OEM distribution as of November 1, 2008. On July 14, 2013, Linux kernel version 3.11 was officially named "Linux For Workgroups" as a tongue-in-cheek reference to "Windows for Workgroups 3.11". On November 7, 2015, the failure of a Windows 3.1 system in Orly Airport of Paris which was responsible for communicating visual range information in foggy weather to pilots caused a temporarily cease of operations. Whether the failure was hardware- or software-based is not specified, though the highlighting of the operating system suggests a software failure. See also 32-bit file access IFSHLP.SYS References 1992 software Products and services discontinued in 2001 3.1x History of Microsoft History of software Products introduced in 1992

Operating System (OS)

Illumos Illumos (stylized as illumos) is a partly free and open-source Unix operating system. It is based on OpenSolaris, which was based on System V Release 4 (SVR4) and the Berkeley Software Distribution (BSD). Illumos comprises a kernel, device drivers, system libraries, and utility software for system administration. This core is now the base for many different open-sourced Illumos distributions, in a similar way in which the Linux kernel is used in different Linux distributions. The maintainers write illumos in lowercase since some computer fonts do not clearly distinguish a lowercase L from an uppercase i: Il (see homoglyph). The project name is a combination of words illuminare from Latin for to light and OS for Operating System. Overview Illumos was announced via webinar on Thursday, 3 August 2010, as a community effort of some core Solaris engineers to create a truly open source Solaris by swapping closed source bits of OpenSolaris with open implementations. The original plan explicitly stated that Illumos would not be a distribution or a fork. However, after Oracle announced discontinuing OpenSolaris, plans were made to fork the final version of the Solaris ON kernel allowing Illumos to evolve into a kernel of its own. , efforts focused on libc, the NFS lock manager, the crypto module, and many device drivers to create a Solaris-like OS with no closed, proprietary code. , development emphasis includes transitioning from the historical compiler, Studio, to GCC. The "userland" software is now built with GNU make and contains many GNU utilities such as GNU tar. Illumos is lightly led by founder Garrett D'Amore and other community members/developers such as Bryan Cantrill and Adam Leventhal, via a Developers' Council. The Illumos Foundation has been incorporated in the State of California as a 501(c)6 trade association, with founding board members Jason Hoffman (formerly at Joyent), Evan Powell (Nexenta), and Garrett D'Amore. As of August 2012, the foundation was in the process of formalizing its by-laws and organizational development. At OpenStorage Summit 2010, the new logo for Illumos was revealed, with official type and branding to follow over. Development Its primary development project, illumos-gate, derives from OS/Net (aka ON), which is a Solaris kernel with the bulk of the drivers, core libraries, and basic utilities, similar to what is delivered by a BSD "src" tree. It was originally dependent on OpenSolaris OS/Net, but a fork was made after Oracle silently decided to close the development of Solaris and unofficially killed the OpenSolaris project. Features ZFS, a combined file system and logical volume manager providing a high level of data integrity for very large storage capacities. Solaris Containers (or Zones), a low overhead implementation of operating-system-level virtualization technology for x86 and SPARC systems. DTrace, a comprehensive dynamic tracing framework for troubleshooting kernel and application problems on production systems in real time. Kernel-based Virtual Machine (KVM), a virtualization infrastructure. KVM supports native virtualization on processors with hardware virtualization extensions. OpenSolaris Network Virtualization and Resource Control (or Crossbow), a set of features that provides an internal network virtualization and quality of service including: virtual NIC (VNIC) pseudo-network interface technology, exclusive ip zones, bandwidth management, and flow control on a per interface and per VNIC basis. Relatives Solaris (operating system) Current distributions Distributions, at illumos.org DilOS, with Debian package manager (dpkg + apt) and virtualization support, available for x86-64 and SPARC. NexentaStor, distribution optimized for virtualization, storage area networks, network-attached storage, and iSCSI or Fibre Channel applications employing the ZFS file system. OmniOS Community Edition, takes a minimalist approach suitable for server use. OpenIndiana, a distribution that is a continuation and fork in the spirit of the OpenSolaris operating system. SmartOS, a distribution for cloud computing with Kernel-based Virtual Machine integration. Tribblix, retro style distribution with modern components, available for x86-64 and SPARC. v9os, a server-only, IPS-based minimal SPARC distribution. XStreamOS, a distribution for infrastructure, cloud, and web development. Discontinued: Dyson, derived from Debian using libc, and SMF init system. OpenSXCE, distribution for developers and system administrators for IA-32/x86-64 x86 platforms and SPARC. See also napp-it, ZFS web interface for Illumos-based NAS or SAN appliances. References Free software OpenSolaris Software forks Solaris software de:OpenSolaris#illumos

Operating System (OS)

Myarc Disk Operating System MDOS (short for Myarc Disk Operating System) is an operating system commercialized by Myarc. It was designed and implemented specifically for the Geneve 9640 by Paul Charlton. MDOS was designed to fully emulate the TI-99/4A computer while providing an advanced (for its time) virtual memory operating environment with full support for mouse, GUI, and complex mathematical applications. In 1993, Beery Miller the publisher of 9640 News, organized a group of Geneve 9640 owners and was able to purchase all rights to the source code for MDOS, Advanced Basic, the PSYSTEM runtime module, and the GPL Interpreter from Myarc and Paul Charlton. Over the years, MDOS has been updated by individuals including T. Tesch, Clint Pulley, Alan Beard, John Johnson, James Schroeder, Mike Maksimik, James Uzzell, Tony Knerr, Beery Miller, and others. Support adding SCSI, IDE, and larger ramdisks were added in the earlier years from the buyout. In late 2020 and early 2021 with the release of the TIPI for the TI-99/4A, the Geneve was interfaced with the TIPI and a Raspberry Pi providing TCP socket access and nearly unlimited high speed hard-drive like file access. A small but active base of users still exist on www.Atariage.com as of 2021 where T. Tesch, Beery Miller, and others provide support. MDOS was written specifically for the TMS9995 16-bit CPU and the Yamaha V9938 video display processor. All source code for the Geneve 9640 is in the public domain. External links Myarc Geneve 9640 Family Computer Myarc Geneve 9640 Software 9640News Software Geneve 9640 - a close look at the system board and sales flyer Geneve 9640 at the Home Computer Museum Geneve items @ Richard Bell's Company Photo of Geneve 9640 booting - HD-based vertical PEB system belonging to Gregory McGill Photo of Geneve showing swan image - from Mainbyte 1988 Dallas TI Fair - mixed Geneve 9640 and TI-99/4A photos Geneve 9640 - at old-computers.com Heatwave BBS - Telnet BBS operating on a Myarc Geneve 9640 under MDOS. Texas Instruments TI-99/4A Products introduced in 1987 Proprietary operating systems Disk operating systems

Operating System (OS)

OpenSUSE openSUSE () is a project that serves to promote the use of free and open-source software. openSUSE is well known for its Linux distributions, mainly Tumbleweed, a tested rolling release, and Leap, a distribution with long-term support. MicroOS and Kubic are new transactional, self-contained distributions for use as desktop or container runtime. The initial release of the community project was a beta version of SUSE Linux 10.0. The current stable fixed release is openSUSE Leap 15.3. Additionally the project creates a variety of tools, such as YaST, Open Build Service, openQA, Snapper, Machinery, Portus, KIWI and OSEM. Overview openSUSE offers Leap, an LTS-style distribution that shares the code base SUSE Linux Enterprise (SLE), effectively making Leap a non-commercial version of its enterprise-grade operating system. Users that prefer more up-to-date free software can use its rolling release distribution Tumbleweed. Users can also use the Open Build Service. Moreover, the flexibility of openSUSE makes it easy to re-purpose for specific goals like running a web- or mail server. Like most Linux distributions, openSUSE includes both a default graphical user interface (GUI) and a command line interface option. Users of openSUSE may choose several desktops environments GUIs like GNOME, KDE, Cinnamon, MATE, LXQt, Xfce. openSUSE supports thousands of software packages across the full range of free software / open source development. The operating system is compatible with a wide variety of hardware on numerous instruction sets including ARM-based single-board computers. Examples include the Raspberry Pi 3 and Pine64 on the ARMv8 platform also known as aarch64, the Banana Pi and BeagleBoard on the ARMv7 instruction set, and the first iteration of the Raspberry Pi on the ARMv6 ISA. RISC-V, PowerPC (PPC64 and PPC64le) and S390 are supported as well. The openSUSE Project The openSUSE Project is a community project to create, promote, improve and document the openSUSE Linux distribution. The openSUSE Project community, sponsored by SUSE, ARM, B1-Systems, Tuxedo Computers and others, develops and maintains various distributions based on Linux. Beyond the distributions and tools, the openSUSE Project provides a web portal for community involvement. The community develops openSUSE collaboratively with its corporate sponsors through the Open Build Service, openQA, writing documentation, designing artwork, fostering discussions on open mailing lists and in Internet Relay Chat channels, and improving the openSUSE site through its wiki interface. The openSUSE Project develops free software and tools and has two main Linux distribution named openSUSE Leap and openSUSE Tumbleweed. The project has several distributions for specific purposes like MicroOS, which is an immutable operating system that hosts container workloads, and the Kubernetes certified distribution Kubic, which is a multi-purpose standalone and Kubernetes container operating system based on openSUSE MicroOS. The project is sponsored by a number of companies and individuals, most notably SUSE, AMD, B1 Systems, Heinlein Support and TUXEDO Computers. The first indication that there should be a community-based Linux distribution called OpenSuSE goes back to a mail of August 3, 2005, in which at the same time the launch of the website opensuse.org was announced. This page was available a few days later. One day later the launch of the community project was officially announced. According to its own understanding, openSUSE is a community that propagates the use of Linux and free software wherever possible. Beside a Linux based distribution it develops tools like the Open Build Service and YaST. Collaboration is open to everyone. Activities The openSUSE Project develops the openSUSE Linux distribution as well as a large number of tools around building Linux distributions like the Open Build Service, KIWI, YaST, openQA, Snapper, Machinery, Portus and more. The project annually hosts free software events. The community's conference is held at a location in Europe and a summit at is held at a location in Asia. Organization The project is controlled by its community and relies on the contributions of individuals, working as testers, writers, translators, usability experts, artists and developers. The project embraces a wide variety of technology, people with different levels of expertise, speaking different languages and having different cultural backgrounds. There is an openSUSE Board which is responsible to lead the overall project. The openSUSE Board provides guidance and supports existing governance structures, but does not direct or control development, since community mechanisms exist to accomplish the goals of the project. The board documents decisions and policies. The project is self-organized without a legal structure, although the establishment of a foundation has been under consideration for some time. SUSE as the main sponsor exerts some influence, but the project is legally independent of SUSE. openSUSE is a "do-ocracy" in which those, who do the work, also decide what happens (those who decide). This primarily refers to desktop and application development, as the sources of the base packages have been coming from SLE since the switch to the Leap development model. To further unify the base, the 'Closing-the-Leap-Gap' project has been started, where openSUSE Leap 15.3 will be completely based on SLE's binary packages. Organizational units There are three main organizational units: openSUSE Board: the board consists of 5 members elected for 2 years at a time, plus the chairman, who is provided by SUSE. The Board serves as a central point of contact, helps with conflict resolutions and communicates community interests to SUSE. As of January 2022, the Board has the following members: Dr. Axel Braun (DE) Maurizio Galli (HK) Neal Gompa (US) Gertjan Lettink (NL) Dr. Gerald Pfeifer (AT), Chairman Attila Pinter (ID) Election Officials: The Election Committee manages and supervises the elections to the openSUSE Board. It consists of three or more volunteers. Membership-Officials: The Membership-Officials are appointed by the Board if interested. The Membership-Officials decide on the admission of contributors to the group of openSUSE members upon request. A member receives, among other things, an @opensuse.org address. Only members may vote in the election to the Board. SUSE Company history Product history In the past, the SUSE Linux company had focused on releasing the SUSE Linux Personal and SUSE Linux Professional box sets which included extensive printed documentation that was available for sale in retail stores. The company's ability to sell an open source product was largely due to the closed-source development process used. Although SUSE Linux had always been free software product licensed with the GNU General Public License (GNU GPL), it was only freely possible to retrieve the source code of the next release 2 months after it was ready for purchase. SUSE Linux' strategy was to create a technically superior Linux distribution with the large number of employed engineers, that would make users willing to pay for their distribution in retail stores. Since the acquisition by Novell in 2003 and with the advent of openSUSE, this has been reversed: starting with version 9.2, an unsupported one-DVD ISO image of SUSE Professional was made available for download. The FTP server continues to operate and has the advantage of "streamlined" installs, permitting the user to download only the packages the user feels they need. The ISO has the advantages of an easy install package, the ability to operate even if the user's network card does not work "out of the box", and less experience needed (i.e., an inexperienced Linux user may not know whether or not to install a certain package, and the ISO offers several preselected sets of packages). The initial stable release from the openSUSE Project, SUSE Linux 10.0, was available for download just before the retail release of SUSE Linux 10.0. In addition, Novell discontinued the Personal version, renaming the Professional version to simply "SUSE Linux", and repricing "SUSE Linux" to about the same as the old Personal version. In 2006 with version 10.2, the SUSE Linux distribution was officially renamed to openSUSE, as it is pronounced similarly to “open source”. Until version 13.2, stable fixed releases with separate maintenance streams from SLE were the project's main offering. From late 2015, openSUSE has been split into two main offerings, Leap, the more conservative fixed release Leap distribution based on SLE, and Tumbleweed, the rolling release distribution focused on integrating the latest stable packages from upstream projects. Over the years, SuSE Linux has gone from a status of a distribution with restrictive, delayed publications (2 months of waiting for those who had not bought the box, without ISOs available, but installation available via FTP) and a closed development model to a free distribution model with immediate and free availability for all and transparent and open development. On April 27, 2011, Attachmate completed its acquisition of Novell. Attachmate split Novell into two autonomous business units, Novell and SUSE. Attachmate made no changes to the relationship between SUSE (formerly Novell) and the openSUSE project. After the 2014 merger of the Attachmate Group with Micro Focus, SUSE reaffirmed their commitment to openSUSE. EQT Partners announced their intent to acquire SUSE on July 2, 2018. There are no expected changes in the relationship between SUSE and openSUSE. This acquisition is the third acquisition of SUSE Linux since the founding of the openSUSE Project and closed on March 15, 2019. Current Distributions openSUSE Tumbleweed Tumbleweed is the flagship of the openSUSE Project. Instead of classical version numbers and periodic updates, a rolling release system is used: Updates happen continuously; previous states of the operating system are saved as "snapshots". Tumbleweed is preferred by openSUSE users as a desktop system. In the old development model, with each new openSUSE release (13.0, 13.1,...) a new rolling release was set-up, which always received new packages. When the new release was at the doorstep, and Tumbleweed was reset to that release, most packages were newer than the ones in the release, which led to problems. With the switch to Leap, the development model was changed completely: according to the Factory First policy all software packages had to be sent to Factory in the first place, before they could be included in a distribution. Out of Factory a daily snapshot is taken and tested in openQA. A successful test is released as the next Tumbleweed snapshot. Unlike other rolling release distributions, Tumbleweed is a tested rolling release, which increases stability dramatically. Technically Tumbleweed is the basis for MicroOS and Kubic. openSUSE Leap Leap is a classic stable distribution approach, one release each year and in between security and bugfixes. This makes Leap very attractive as server operating system, but as well for Desktops since it requires little maintenance effort. For the version released in the fall of 2015, the development team settled on the name openSUSE Leap with the deviating version number 42.1. As in the openSUSE version 4.2 from May 1996, which was called S.u.S.E. Linux at the time, the number 42 refers to the question about "life, the universe and everything" in the Hitchhiker's Guide to the Galaxy book series. After that, the basis packages are received from the SUSE Linux Enterprise, while applications and desktops come from Tumbleweed. At the openSUSE conference held in Nuremberg in 2016, statistics were announced that since the conceptual reorientation with openSUSE Leap 42.1, increasing user numbers had been recorded. According to this, the number of downloads is 400,000 DVD-images per month with an increasing tendency. Each month, 1,600 installations would be added, and 500,000 packages would be installed. The number of Tumbleweed users is 60,000, half of whom frequently perform updates. Thus, the number of Tumbleweed installations had doubled in the last year. Other findings from the statistics are that most installations are done via DVD images. The dominant architecture is x64. The geographical distribution of users has hardly changed according to these figures. One third of users are from Germany, 12% are found in the USA, 5% in Russia and 3% in Brazil. For the openSUSE Leap 15.3 release, the repository for openSUSE Leap and SUSE Linux Enterprise (SLE) was merged and now contains the same source code and binary packages. SLE 15 will be supported until 31 July 2028 openSUSE MicroOS MicroOS is a minimalistic, self-maintained and transactional system, which is primarily, but not exclusively, intended for use in edge computing or as container runtime. Some even use it as desktop system. MicroOS takes a completely new approach to address the needs of Edge- or Cloud-computing: It minimizes the need for maintenance by running from a read-only file system, which prevents accidental changes as well as malware attacks. The system is self-contained and transactional, which means that it updates itself in an all-or-nothing approach (transactional) and rolls back to its previous stage in case something goes wrong. The transactional update does not affect the running system. Basically all software available for Tumbleweed is also available for MicroOS. As it comes with podman Container-Runtime, MicroOS is the perfect Container-Host. MicroOS Desktop is the focus for the 2021 Hackweek openSUSE Kubic Kubic is a Container-as-a-Service Platform, based on MicroOS. It comes with Kubernetes and is designed for large container environments. The openSUSE Community maintains a number of containers in their registry. The configuration was originally done with Salt, but later it was switched to Kubeadm. Kubic shares the codebase with Tumbleweed and MicroOS and thus allows transactional updates Factory project The Factory project is the rolling development code base for openSUSE Tumbleweed, Factory is mainly used as an internal term for openSUSE's distribution developers, and the target project for all contributions to openSUSE's main code base. There is a constant flow of packages going into Factory. There is no freeze; therefore, the Factory repository is not guaranteed to be fully stable and is not intended to be used by humans. The core system packages receive automated testing via openQA. When automated testing is completed and the repository is in a consistent state, the repository is synced to the download mirrors and published as openSUSE Tumbleweed, That usually happens several times a week. Features YaST Control Center SUSE includes an installation and administration program called YaST ("Yet another Setup Tool") which handles hard disk partitioning, system setup, RPM package management, online updates, network and firewall configuration, user administration and more in an integrated interface. By 2010, many more YaST modules were added, including one for Bluetooth support. It also controls all software applications. SaX2 was once integrated into YaST to change monitor settings, however with openSUSE 11.3 SaX2 has been removed. The GTK user interface was removed starting with Leap 42.1, however the ncurses and Qt interfaces remain. AutoYaST AutoYaST is part of YaST2 and is used for automatic installation. The configuration is stored in an XML file and the installation happens without user interaction. WebYaST WebYaST is a web interface version of YaST. It can configure settings and updates of the openSUSE machine it is running on. It can also shutdown and check the status of the host. ZYpp package management ZYpp (or libzypp) is a Linux software management engine. ZYpp is the backend for zypper, the default command line package management tool for openSUSE. Build Service The Open Build Service provides software developers with a tool to compile, release and publish their software for many distributions, including Mandriva, Ubuntu, Fedora and Debian. It typically simplifies the packaging process, so developers can more easily package a single program for many distributions, and many openSUSE releases, making more packages available to users regardless of what distribution version they use. It is published under the GNU GPLv2+. Default use of Delta RPM By default, OpenSUSE uses Delta RPMs when updating an installation. A Delta RPM contains the difference between an old and new version of a package. This means that only the changes between the installed package and the new one, are downloaded. This reduces bandwidth consumption and update time, which is especially important on slow Internet connections. Desktop innovation KDE SUSE was a leading contributor to the KDE project for many years. SUSE's contributions in this area have been very wide-ranging, and affecting many parts of KDE such as kdelibs and KDEBase, Kontact, and kdenetwork. Other notable projects include: KNetworkManager – a front-end to NetworkManager and Kickoff – a new K menu for KDE Plasma Desktop. From openSUSE Leap 42.1 to 15.0, the default Plasma 5 desktop for openSUSE used the traditional cascading Application Menu in place of the upstream default Kickoff-like Application Launcher menu. The openSUSE Leap KDE experience is built on long term support versions of KDE Plasma, starting with openSUSE Leap 42.2. With openSUSE Leap 15.1, the Plasma 5 desktop now again defaults to the Kickoff-style application menu. GNOME The Ximian group became part of Novell, and in turn made and continued several contributions to GNOME with applications such as F-Spot, Evolution and Banshee. The GNOME desktop used the slab instead of the classic double-panelled GNOME menu bars from openSUSE 10.2 to openSUSE 11.4. In openSUSE 12.1 slab was replaced with the upstream GNOME Shell and GNOME Fallback designs. Starting with openSUSE Leap 15.0, GNOME on Wayland is offered as the default GNOME session. GNOME Classic, GNOME on Xorg, and "GNOME SLE" are offered as alternative sessions to the more upstream Wayland-based session. Releases 10.x series The initial stable release from the openSUSE Project was SUSE Linux 10.0, released on October 6, 2005. This was released as a freely downloadable ISO image and as a boxed retail package, with certain bundled software only included in the retail package. On May 11, 2006, the openSUSE Project released SUSE Linux 10.1, with the mailing list announcement identifying Xgl, NetworkManager, AppArmor and Xen as prominent features. For their third release, the openSUSE Project renamed their distribution, releasing openSUSE 10.2 on December 7, 2006. Several areas that developers focused their efforts on were reworking the menus used to launch programs in KDE and GNOME, moving to ext3 as the default file system, providing support for internal readers of Secure Digital cards commonly used in digital cameras, improving power management framework (more computers can enter suspended states instead of shutting down and starting up) and the package management system. This release also featured version 2.0 of Mozilla Firefox. The fourth release, openSUSE 10.3, was made available as a stable version on October 4, 2007. An overhaul of the software package management system (including support for 1-Click-Install), legal MP3 support from Fluendo and improved boot-time are some of the areas focused on for this release. 11.x series openSUSE 11.0 was released on June 19, 2008. It includes the latest version of GNOME and two versions of KDE (the older, stable 3.5.9 and the newer 4.0.4). It comes in three freely downloadable versions: a complete installation DVD (including GNOME, KDE3, and KDE4), and two Live CDs (GNOME, and KDE4 respectively). A KDE3 Live CD was not produced due to limited resources. Package management and installation were made significantly faster with ZYpp. openSUSE 11.1 was released on December 18, 2008. Updated software includes GNOME 2.24.1, Plasma 4.1.3 + K Desktop Environment 3.5.10, OpenOffice.org 3.0, VirtualBox 2.0.6, Compiz 0.7.8, Zypper 1.0.1, continued improvement in the software update stack, X.Org 7.4, Xserver 1.5.2, and Linux kernel 2.6.27.7. openSUSE 11.1 was the first Evergreen supported release. openSUSE 11.2 was released on November 12, 2009. It includes Plasma 4.3, GNOME 2.28, Mozilla Firefox 3.5, OpenOffice.org 3.1, improved social network support, updated filesystems such as Ext4 as the new default and support for Btrfs, installer support for whole-disk encryption, significant improvements to YaST and zypper, and all ISO images are hybrid and now support both USB and CD-ROM boot. openSUSE 11.3 was released on July 15, 2010. It includes Plasma 4.4.4, GNOME 2.30.1, Mozilla Firefox 3.6.6, OpenOffice.org 3.2.1, SpiderOak support, support for the Btrfs filesystem and support for LXDE. It also updates the Linux kernel to version 2.6.34. openSUSE 11.4 was finished on March 3, 2011 and released on March 10, 2011. It includes Plasma 4.6.0, GNOME 2.32.1, Mozilla Firefox 4.0 beta 12, and switched from OpenOffice.org to LibreOffice 3.3.1. It updates the Linux kernel to version 2.6.37. 12.x series openSUSE 12.1 was released on November 16, 2011. This includes Plasma 4.7 and GNOME 3.2 and Firefox 7.0.1. The Linux kernel was updated to 3.1.0 It also introduced an advanced disk snapshot tool, called Snapper, for managing Btrfs snapshots. openSUSE 12.1 was also the first release of openSUSE to use systemd by default rather than the traditional System V init. Users can still select to boot to System V init at startup time. openSUSE 12.2 was to be released on July 11, 2012, but was postponed due to persistent stability issues. The final release candidate was eventually announced on August 2, 2012 and the final release date was September 5, 2012. 12.2 includes the desktop environments Plasma 4.8, GNOME 3.4, Firefox 14.0.1, and Xfce 4.10 and now uses Plymouth and GRUB 2 by default. openSUSE 12.3 was released on schedule on March 13, 2013. This includes Plasma 4.10, GNOME 3.6, Firefox 19.0, LibreOffice 3.6, and the removal of SuSEconfig. Also, the Live CD images were replaced with Live USB images, and an Xfce rescue image. 13.x series openSUSE 13.1 was released on November 19, 2013, and includes updates to Plasma 4.11, GNOME 3.10, Firefox 25.0, and LibreOffice 4.1. Some other changes include a YaST port to Ruby, the LightDM KDE greeter, and experimental Wayland support in the GNOME Shell and KDE Plasma Desktop. openSUSE 13.1 is an Evergreen supported release, meaning it will receive community patches for 18 months after SUSE support ends. openSUSE 13.2 was released on November 4, 2014, and includes updates to Plasma 4.11, KDE Applications 4.14, GNOME 3.14.1, Firefox 33.0 and LibreOffice 4.3.2.2. Leap 42.x series The openSUSE team decided that the next version would be based on SUSE Linux Enterprise Server (SLES). They named it "Leap 42" (42 being the answer to life, the universe and everything); Still version 15 comes thereafter. Leap 42.2 features KDE Plasma 5.8 LTS as its default desktop environment. Leap 15.x series openSUSE Leap 15 is based on SUSE Linux Enterprise (SLE). The name "Leap 15" is meant to match the SUSE Linux Enterprise version it is based on. Leap 15 (just like SUSE Linux Enterprise 15) uses Linux kernel 4.12 LTS, and the default desktop is KDE Plasma 5.12 LTS. It also allows users to switch to its enterprise variant - SUSE Linux Enterprise 15. Version history From 2009 to 2014, the openSUSE project aimed to release a new version every eight months. Prior to the Leap series, versions 11.2-13.2 were provided with critical updates for two releases plus two months, which resulted in an expected support lifetime of 18 months. Starting with version Leap 42.1 (after version 13.2), each major release is expected to be supported for at least 36 months, until the next major version is available (e.g. 42.1, 15.0), aligned with SUSE Linux Enterprise Releases. Each minor release (e.g. 42.1, 42.2, etc.) is expected to be released annually, aligned with SUSE Linux Enterprise Service Packs, and users are expected to upgrade to the latest minor release within 6 months of its availability, leading to an expected support lifecycle of 18 months as earlier. Tumbleweed is updated on a rolling basis, and requires no upgrades beyond the regular installation of small updates and snapshots. Evergreen was a community effort to prolong maintenance of selected openSUSE versions after they reached official end-of-life before the Leap series. Reception Jesse Smith from DistroWatch Weekly reviewed openSUSE Leap 15.0, lauding the "work that has gone into the system installer", simplify for new users, but criticized the lack of media support, and performance issues, like a slow startup or slow shutdown. See also SUSE Linux SUSE Linux Enterprise Red Hat Enterprise Linux Fedora Linux References External links openSUSE Roadmap (schedule of current and upcoming releases) ARM Linux distributions KDE LXQt PowerPC operating systems Rolling Release Linux distributions RPM-based Linux distributions SUSE Linux X86-64 Linux distributions Linux distributions

Operating System (OS)

Damn Small Linux Damn Small Linux (DSL) was a computer operating system for the x86 family of personal computers. It is free and open-source software under the terms of the GNU GPL and other free and open source licenses. It was designed to run graphical user interface applications on older PC hardware, for example, machines with 486 and early Pentium microprocessors and very little random-access memory (RAM). DSL is a Live CD with a size of 50 megabytes (MB). What originally began as an experiment to see how much software could fit in 50 MB eventually became a full Linux distribution. It can be installed on storage media with small capacities, like bootable business cards, USB flash drives, various memory cards, and Zip drives. History DSL was originally conceived and maintained by John Andrews. For five years the community included Robert Shingledecker who created the MyDSL system, DSL Control Panel and other features. After issues with the main developers, Robert was, by his account, exiled from the project. He currently continues his work on Tiny Core Linux which he created in April 2008. DSL was originally based on Model-K, a 22 MB stripped down version of Knoppix, but soon after was based on Knoppix proper, allowing much easier remastering and improvements. System requirements DSL supports only x86 PCs. The minimum system requirements are a 486 processor and 8 MB of RAM. DSL has been demonstrated browsing the web with Dillo, running simple games and playing music on systems with a 486 processor and 16 MB of RAM. The system requirements are higher for running Mozilla Firefox and optional add-ons such as the OpenOffice.org office suite. Features , version 4.4.10 of DSL, released November 18, 2008, was current. It includes the following software: Text editors: Beaver, Nano, Vim File managers: DFM, emelFM Graphics: mtPaint (raster graphics editor), xzgv (image viewer) Multimedia: gphone, XMMS with MPEG-1 and Video CD (VCD) support Office: Siag Office (spreadsheet program), Ted (word processor) with spell checker, Xpdf (viewer for Portable Document Format (PDF) documents) Internet: Web browsers: Dillo, Firefox, Netrik Sylpheed (E-mail client) naim (AOL Instant Messenger (AIM), ICQ, and IRC client) AxyFTP (File Transfer Protocol (FTP) client), BetaFTPD (FTP server) Monkey (web server) Server Message Block (SMB) client Rdesktop (Remote Desktop Protocol (RDP) client, Virtual Network Computing (VNC) viewer Others: Dynamic Host Configuration Protocol (DHCP) client, Secure Shell (SSH) and secure copy protocol (SCP) client and server; Point-to-Point Protocol (PPP), Point-to-Point Protocol over Ethernet (PPPoE), Asymmetric Digital Subscriber Line (ADSL) support; FUSE, Network File System (NFS), SSH Filesystem (SSHFS) support; UnionFS; generic and Ghostscript printing support; PC card, Universal Serial Bus (USB), Wi-Fi support; calculator, games, system monitor; many command-line tools DSL has built-in scripts to download and install Advanced Packaging Tool (APT). Once APT is enabled, a user can install packages from Debian's repositories. Also, DSL hosts software ranging from large applications like OpenOffice.org and GNU Compiler Collection (GCC), to smaller ones such as aMSN, by means of the MyDSL system, which allows convenient one-click download and installing of software. Files hosted on MyDSL are called extensions. As of June 2008, the MyDSL servers were hosting over 900 applications, plugins, and other extensions. Boot options Boot options are also called "cheat codes" in DSL. Automatic hardware detection may fail, or the user may want to use something other than the default settings (language, keyboard, VGA, fail safe graphics, text mode...). DSL allows the user to enter one or more cheat codes at the boot prompt. If nothing is entered, DSL will boot with the default options. Cheat codes affect many auto-detection and hardware options. Many cheat codes also affect the GUI. The list of cheat codes can be seen at boot time and also at the DSL Wiki. You can also Run PartyDisk on DSL. The MyDSL system MyDSL is handled and maintained mostly by Robert Shingledecker and hosted by many organizations, such as ibiblio and Belgium's BELNET. There are 2 areas of MyDSL: regular and testing. The regular area contains extensions that have been proven stable enough for everyday use and is broken down into different areas such as apps, net, system, and uci (Universal Compressed ISO - Extensions in .uci format are mounted as a separate file system to minimize RAM use). The testing area is for newly submitted extensions that theoretically work well enough, but may have any number of bugs. Versions and ports Release timeline Flavours The standard flavour of DSL is the Live CD. There are also other versions available: 'Frugal' installation: DSL's 'cloop' image is installed, as a single file, to a hard disk partition. This is likely more reliable and secure than a traditional hard drive installation, since the cloop image cannot be directly modified; any changes made are only stored in memory and discarded upon rebooting. 'dsl-version-embedded.zip': Includes QEMU for running DSL inside Windows or Linux. 'dsl-version-initrd.iso': Integrates the normally-separate cloop image into the initrd image; this allows network booting, using PXE. As a regular toram boot, requires at least 128mb ram. 'dsl-version-syslinux.iso': Boots using syslinux floppy image emulation instead of isolinux; for very old PCs that cannot boot with isolinux. 'dsl-version-vmx.zip': A virtual machine hard drive image that can be run in VirtualBox, VMware Workstation or VMware Player. DSL-N: A larger version of DSL that exceeds the 50 MB limit of business-card CDs. DSL-N uses version 2 of the GTK+ widget toolkit and version 2.6 of the Linux kernel. The latest release of DSL-N, 0.1RC4, is 95 MB in size. It is not actively maintained. One can also boot DSL using a boot-floppy created from one of the available floppy images ('bootfloppy.img'; 'bootfloppy-grub.img'; 'bootfloppy-usb.img'; or 'pcmciabootfloppy.img') on very old computers, where the BIOS does not support the El Torito Bootable CD Specification. The DSL kernel is loaded from the floppy disk into RAM, after which the kernel runs DSL from the CD or USB drive. Ports and derivatives DSL was ported to the Xbox video game console as X-DSL. X-DSL requires a modified Xbox. It can run as a Live CD or be installed to the Xbox hard drive. Users have also run X-DSL from a USB flash drive, using the USB adaptor included with Phantasy Star Online, which plugs into the memory card slot and includes one USB 1.1 port. X-DSL boots into a X11-based GUI; the Xbox controller can be used to control the mouse pointer and enter text using a virtual keyboard. X-DSL has a Fluxbox desktop, with programs for E-mail, web browsing, word processing and playing music. X-DSL can be customized by downloading extensions from the same MyDSL servers as DSL. Linux distributions derived from Damn Small Linux include Hikarunix, used for a CD image that runs the game of Go released in 2005, and Damn Vulnerable Linux. Live USB A Live USB of Damn Small Linux can be created manually or with applications like UNetbootin. See List of tools to create Live USB systems for full list. Status Due to infighting among the project's originators and main developers, DSL development seemed to be at a standstill for a long time, and the future of the project was uncertain, much to the dismay of many of the users. On July 8, 2012, John Andrews (the original developer) announced that a new release was being developed. The DSL website, including the forums which were once inaccessible, were back, as well. The first RC of the new 4.11 was released on August 3, 2012, followed by a second one on September 26. The damnsmalllinux.org site was inaccessible again sometime in 2015 to February 2016. As of March 27, 2016, it was again accessible for some time, but as of February 10, 2019 was inaccessible yet again. As of 2021 it was accessible. See also Comparison of Linux distributions Lightweight Linux distribution List of Linux distributions List of Linux distributions that run from RAM Tiny Core Linux, the project Robert Shingledecker began References External links Damn Small Linux website USB DSL tutorial DistroWatch interview Archive.org's DSL ISO Archive Reviews IBM developerWorks review OSNews review (2004), OSNews review (2011) Tech Source From Bohol review Review of version 4.4.10 at IT Reviews Knoppix LiveDistro Light-weight Linux distributions Live USB Debian-based distributions Lua (programming language)-scripted software Lightweight Unix-like systems Linux distributions without systemd Linux distributions

Operating System (OS)

JavaOS JavaOS is an operating system based on a Java virtual machine and predominantly used on SIM cards to run applications on behalf of operators and security services. It was originally developed by Sun Microsystems. Unlike Windows, macOS, Unix, or Unix-like systems which are primarily written in the C programming language, JavaOS is primarily written in Java. It is now considered a legacy system. History The Java programming language was introduced by Sun in May 1995. Jim Mitchell and Peter Madany at JavaSoft designed a new operating system, codenamed Kona, written completely in Java. In March 1996, Tom Saulpaugh joined the now seven-person Kona team to design an I/O architecture, having come from Apple as Mac OS engineer since June 1985 and co-architect of Copland. JavaOS was first evangelized in a Byte article. In 1996, JavaSoft's official product announcement described the compact OS designed to run "in anything from net computers to pagers". In early 1997, JavaSoft transferred JavaOS to SunSoft. In late 1997, Bob Rodriguez led the team to collaborate with IBM who then marketed the platform, accelerated development, and made significant key architectural contributions to the next release of JavaOS, eventually renamed JavaOS for Business. IBM indicated its focus was more on network computer thin clients, specifically to replace traditional "green screen" and UNIX terminals, and to implement single application clients. The Chorus distributed real-time operating system was used for its microkernel technology. This began with Chorus Systèmes SA, a French company, licensing JavaOS from Sun and replaced the earlier JavaOS hardware abstraction layer with the Chorus microkernel, thereby creating the Chorus/Jazz product, which was intended to allow Java applications to run in a distributed, real-time embedded system environment. Then in September 1997, it was announced that Sun Microsystems was acquiring Chorus Systèmes SA. JavaSoft has granted licenses to more than 25 manufacturers, including Oracle Corp, Acer Inc., Xerox, Toshiba Corp, and Nokia. IBM and Sun announced the cooperation for JavaOS for Business at the end of March 1998. In 1999, Sun and IBM announced the discontinuation of the JavaOS product. As early as 2003, Sun materials referred to JavaOS as a "legacy technology", recommending migration to Java ME, leaving the choice of specific OS and Java environment to the implementer. Overview JavaOS is based on a hardware architecture native microkernel, running on platforms including ARM, PowerPC, SPARC, StrongARM, and IA-32 (x86). The Java virtual machine runs on top of the microkernel. All device drivers are written in Java and executed by the virtual machine. A graphics and windowing system implementing the AWT API is also written in Java. JavaOS was designed to run on embedded systems and has applications in devices such as set-top boxes, networking infrastructure, and ATMs. It comes with the JavaStation. See also JX (operating system) JNode (operating system) SavaJe Android Vino (operating system) Java Desktop System ChorusOS Inferno (operating system) References External links ARM operating systems Embedded operating systems Java platform Microkernels Microkernel-based operating systems Object-oriented operating systems Sun Microsystems software

Operating System (OS)

Unix-like A Unix-like (sometimes referred to as UN*X or *nix) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-like application is one that behaves like the corresponding Unix command or shell. There is no technical standard defining the term, and opinions can differ about whether or the degree to which a particular operating system or application is Unix-like. The term can include free and open-source operating systems inspired by Bell Labs' Unix or designed to emulate its features, commercial and proprietary workalikes, and versions based on the licensed UNIX source code, which may be sufficiently Unix-like to pass certification and bear the UNIX trademark. Definition The Open Group owns the UNIX trademark and administers the Single UNIX Specification, with the "UNIX" name being used as a certification mark. They do not approve of the construction "Unix-like", and consider it a misuse of their trademark. Their guidelines require "UNIX" to be presented in uppercase or otherwise distinguished from the surrounding text, strongly encourage using it as a branding adjective for a generic word such as "system", and discourage its use in hyphenated phrases. Other parties frequently treat "Unix" as a genericized trademark. Some add a wildcard character to the name to make an abbreviation like "Un*x" or "*nix", since Unix-like systems often have Unix-like names such as AIX, A/UX, HP-UX, IRIX, Linux, Minix, Ultrix, Xenix, and XNU. These patterns do not literally match many system names, but are still generally recognized to refer to any UNIX system, descendant, or work-alike, even those with completely dissimilar names such as Darwin/macOS, illumos/Solaris or FreeBSD. In 2007, Wayne R. Gray sued to dispute the status of UNIX as a trademark, but lost his case, and lost again on appeal, with the court upholding the trademark and its ownership. History "Unix-like" systems started to appear in the late 1970s and early 1980s. Many proprietary versions, such as Idris (1978), UNOS (1982), Coherent (1983), and UniFlex (1985), aimed to provide businesses with the functionality available to academic users of UNIX. When AT&T allowed relatively inexpensive commercial binary sub-licensing of UNIX in 1979, a variety of proprietary systems were developed based on it, including AIX, HP-UX, IRIX, SunOS, Tru64, Ultrix, and Xenix. These largely displaced the proprietary clones. Growing incompatibility among these systems led to the creation of interoperability standards, including POSIX and the Single UNIX Specification. Various free, low-cost, and unrestricted substitutes for UNIX emerged in the 1980s and 1990s, including 4.4BSD, Linux, and Minix. Some of these have in turn been the basis for commercial "Unix-like" systems, such as BSD/OS and macOS. Several versions of (Mac) OS X/macOS running on Intel-based Mac computers have been certified under the Single UNIX Specification. The BSD variants are descendants of UNIX developed by the University of California at Berkeley with UNIX source code from Bell Labs. However, the BSD code base has evolved since then, replacing all of the AT&T code. Since the BSD variants are not certified as compliant with the Single UNIX Specification, they are referred to as "UNIX-like" rather than "UNIX". Categories Dennis Ritchie, one of the original creators of Unix, expressed his opinion that Unix-like systems such as Linux are de facto Unix systems. Eric S. Raymond and Rob Landley have suggested that there are three kinds of Unix-like systems: Genetic UNIX Those systems with a historical connection to the AT&T codebase. Most commercial UNIX systems fall into this category. So do the BSD systems, which are descendants of work done at the University of California, Berkeley in the late 1970s and early 1980s. Some of these systems have no original AT&T code but can still trace their ancestry to AT&T designs. Trademark or branded UNIX These systemslargely commercial in naturehave been determined by the Open Group to meet the Single UNIX Specification and are allowed to carry the UNIX name. Most such systems are commercial derivatives of the System V code base in one form or another, although Apple macOS 10.5 and later is a BSD variant that has been certified, EulerOS and Inspur K-UX are Linux distributions that have been certified, and a few other systems (such as IBM z/OS) earned the trademark through a POSIX compatibility layer and are not otherwise inherently Unix systems. Many ancient UNIX systems no longer meet this definition. Functional UNIX Broadly, any Unix-like system that behaves in a manner roughly consistent with the UNIX specification, including having a "program which manages your login and command line sessions"; more specifically, this can refer to systems such as Linux or Minix that behave similarly to a UNIX system but have no genetic or trademark connection to the AT&T code base. Most free/open-source implementations of the UNIX design, whether genetic UNIX or not, fall into the restricted definition of this third category due to the expense of obtaining Open Group certification, which costs thousands of dollars for commercial closed source systems. Around 2001, Linux was given the opportunity to get a certification including free help from the POSIX chair Andrew Josey for the symbolic price of one dollar. There have been some activities to make Linux POSIX-compliant, with Josey having prepared a list of differences between the POSIX standard and the Linux Standard Base specification, but in August 2005, this project was shut down because of missing interest at the LSB work group. Compatibility layers Some non-Unix-like operating systems provide a Unix-like compatibility layer, with varying degrees of Unix-like functionality. IBM z/OS's UNIX System Services is sufficiently complete as to be certified as trademark UNIX. Cygwin, MSYS, and MSYS2 each provide a GNU environment on top of the Microsoft Windows user API, sufficient for most common open source software to be compiled and run. The MKS Toolkit and UWIN are comprehensive interoperability tools which allow the porting of Unix programs to Windows. Windows NT-type systems have a POSIX environmental subsystem. Subsystem for Unix-based Applications (previously Interix) provides Unix-like functionality as a Windows NT subsystem (discontinued). Windows Subsystem for Linux provides a Linux-compatible kernel interface developed by Microsoft and containing no Linux code, with Ubuntu user-mode binaries running on top of it. Other means of Windows-Unix interoperability include: The above Windows packages can be used with various X servers for Windows Hummingbird Connectivity provides several ways for Windows machines to connect to Unix and Linux machines, from terminal emulators to X clients and servers, and others The Windows Resource Kits for versions of Windows NT include a Bourne Shell, some command-line tools, and a version of Perl Hamilton C shell is a version of csh written specifically for Windows. See also List of Unix-like systems Berkeley Software Distribution Linux kernel and Linux distribution List of Linux distributions List of Unix commands List of operating systems Free Software Foundation and GNU Project References External links Unix-like Definition, by The Linux Information Project (LINFO) UNIX history a history time line graph of most UNIX and Unix-like systems by Éric Lévénez Unix Operating system families

Operating System (OS)

Operating context An operating context (OC) for an application is the external environment that influences its operation. For a mobile application, the OC is defined by the hardware and software environment in the device, the target user, and other constraints imposed by various other stakeholders, such as a carrier. This concept differs from the operating system (OS) by the impact of these various other stakeholders. Example Here is an example of one device, with one operating system, changing its operating context without changing the OS. A user with a mobile phone changes SIM cards, removing card A, and inserting card B. The phone will now make any network calls over cell phone carrier B's network, rather than A's. Any applications running on the phone will run in a new operating context, and will often have to change functionality to adapt to the abilities, and business logic, of the new carrier. The network, spectrum, and wireless protocol all change in this example. These changes must be reflected back to the user, so the user knows what experience to expect, and thus these changes all change the user interface (UI) also. Hardware agnostic context Situations exist where one can program in a context, with less concern about what hardware it will actually run on. Examples include Flash and Android. Unfortunately, it also quite common that code in a hardware free context will see hardware specific bugs. This is common with software written for, that interacts more directly with, personal computer (PC) hardware, or mobile phones. References Fragmentation of Mobile Applications Operating context is defined in this article See also List of operating systems Comparison of operating systems Operational context Computing terminology Mobile technology

Operating System (OS)

GEOS (8-bit operating system) GEOS (Graphic Environment Operating System) is a discontinued operating system from Berkeley Softworks (later GeoWorks). Originally designed for the Commodore 64 with its version being released in 1986, enhanced versions of GEOS later became available in 1987 for the Commodore 128 and in 1988 for the Apple II series of computers. A lesser-known version was also released for the Commodore Plus/4. GEOS closely resembles early versions of the classic Mac OS and includes a graphical word processor (geoWrite) and paint program (geoPaint). A December 1987 survey by the Commodore-dedicated magazine Compute!'s Gazette found that nearly half of respondents used GEOS. For many years, Commodore bundled GEOS with its redesigned and cost-reduced C64, the C64C. At its peak, GEOS was the third-most-popular microcomputer operating system in the world in terms of units shipped, trailing only MS-DOS and Mac OS (besides the original Commodore 64's KERNAL). Other GEOS-compatible software packages were available from Berkeley Softworks or from third parties, including a reasonably sophisticated desktop publishing application called geoPublish and a spreadsheet called geoCalc. While geoPublish is not as sophisticated as Aldus Pagemaker and geoCalc not as sophisticated as Microsoft Excel, the packages provide reasonable functionality, and Berkeley Softworks founder Brian Dougherty claimed the company ran its business using its own software on Commodore 8-bit computers for several years. Development Written by a group of programmers, the GEOS Design Team: Jim DeFrisco, Dave Durran, Michael Farr, Doug Fults, Chris Hawley, Clayton Jung, and Tony Requist, led by Dougherty, who cut their teeth on limited-resource video game machines such as the Atari 2600, GEOS was revered for what it could accomplish on machines with 64–128 kB of RAM memory and 1–2 MHz of 8-bit processing power. Unlike many pieces of proprietary software for the C64 and C128, GEOS takes full advantage of many of the add-ons and improvements available for these systems. Commodore's 1351 mouse is supported by GEOS, as are its various RAM expansion units. GEOS 128 also fully supports the C128's 640×200 high-resolution VDC display mode through a compatible RGB monitor. The C64 version of GEOS incorporates a built-in fast loader, called diskTurbo, that significantly increases the speed of drive access on the slow 1541. GEOS is the first Commodore software that could use a floppy disk as swap space or virtual memory. GEOS 128 can take advantage of the C128's enhanced "burst mode" in conjunction with the 1571 and 1581 drives. The Commodore version of GEOS uses a copy protection scheme that renders users' disks unbootable if it detects that the disk has been illegally duplicated. Via Berkeley's special geoCable interface converter or other third-party interfaces to connect standard RS-232 or Centronics printers to the Commodore serial bus, GEOS supports a wide variety of printers, including HP PCL printers and the Apple LaserWriter. This ability to print to high-end printers was a major factor in making GEOS a desktop publishing platform. The Apple II version of GEOS was released as freeware in August 2003. The Commodore 64/128 versions followed in February 2004. The latest GEOS desktop suite for IBM PC compatibles is Breadbox Ensemble. Revivals were seen in the OmniGo handhelds, Brother GeoBook line of laptop-appliances, and the NewDeal Office package for PCs. Related code found its way to earlier "Zoomer" PDAs, creating an unclear lineage to Palm, Inc.'s later work. Nokia used GEOS as a base operating system for their Nokia Communicator series, before switching to EPOC (Symbian). GEOS versions 1986: GEOS for Commodore 64 1987: GEOS for Commodore C128, Commodore Plus/4 (unofficial) 1988: GEOS for Apple II, GEOS V2.0 for Commodore C64, GEOS V2.1 for Apple II 1989: GEOS V2.0 for Commodore C128 Reverse engineering efforts On August 19, 2016, Michael Steil posted in his blog that the source code for GEOS 2.0 for Commodore C64 had been fully reverse-engineered and suitable for the cc65 compiler suite. The reverse-engineered source code has been made available at GitHub. GEOS products and applications Dozens of official and third-party applications and other products were produced for GEOS. Among the most important and popular were the following: geoBASIC geoCable geoCalc geoChart geoDex geoDraw geoFAX geoFile geoFont geoLabel geoPaint geoPrint geoProgrammer geoPublish geoSpell geoWrite geoWrite Workshop geoRAM Writer 64 (Timeworks) See also Contiki PC/GEOS References Further reading External links Breadbox Home of the GEOS operating system (down, archived here at the Internet Archive) The Commodore GEOS FAQ v1.5.0 – By Bo Zimmermann GEOS: The Graphical Operating System A lengthy review of GEOS and its history 1986 software Operating system families Apple II software Commodore 128 software Commodore 64 software Graphical user interfaces Proprietary operating systems Window-based operating systems

Operating System (OS)

Hanthana Linux (operating system) Hanthana Linux is a computer operating system based on the Fedora distribution, distributed as free and open source software. Hanthana Linux is among the active Fedora remixes. It is specially designed to cater to the needs of Sri Lankan computer users who are unable to access the Internet frequently, with many most-wanted applications built in. Hanthana is developed by the Sri Lanka-based Hanthana Community. History and development process Hanthana is a remix of the Fedora operating system. The original aim of the Hanthana team was to create an easy-to-use Linux desktop with as many useful applications preloaded, as downloading applications through Internet is hard for many rural areas of Sri Lanka. Hanthana's first release was on 19 September 2009. Since then, Hanthana community has released new versions of Hanthana every six months with commitment to support each release for eighteen months by providing security fixes, patches to critical bugs and minor updates to programs. Once a new Fedora version is released, after some time, the corresponding Hanthana version will be released and it contains all the software updates up to the date of release. Hanthana packages are based on packages from Fedora's: both distributions use RedHat's rpm package format and package management tools Yum (PackageKit). Features Hanthana is composed of many software packages, of which the majority are distributed under a free software license, making an exception only for some proprietary hardware drivers. The main license used is the GNU General Public License (GNU GPL) which, along with the GNU Lesser General Public License (GNU LGPL), explicitly declares that users are free to run, copy, distribute, study, change, develop and improve the software. On the other hand, there is also proprietary software available that can run on Hanthana. Hanthana focuses on usability, security and stability. Hanthana also emphasizes accessibility and internationalization to reach as many people as possible. From the start UTF-8 is the default character encoding, which allows for support of a variety of non-Roman scripts. Hanthana comes installed with a wide range of software that includes LibreOffice, Firefox, Pidgin, Transmission, GIMP, and several lightweight games (such as Sudoku and chess). Installation Installation of Hanthana is generally performed with the Live DVD. Hanthana can be run directly from the DVD (albeit with a significant performance loss), allowing a user to "test-drive" the OS for hardware compatibility and driver support. Users can download a disk image (.iso) of the DVD, which can then either be written to a physical medium (DVD), or optionally run directly from a hard drive (via UNetbootin or GRUB). Following minimum hardware specifications will ensure your work on Hanthana easier and faster: For text mode recommended processor : 200 MHz Pentium Pro or faster minimum memory (RAM): 256 MB For graphical mode recommended processor : 400 MHz Pentium Pro or faster minimum memory (RAM): 640 MB recommended memory (RAM): 1152 MB Hard disk minimum free space of 15GB A DVD ROM Latest Version Hanthana Developer team has announced the release of Hanthana Linux 30 (Vishwa) ), a Fedora-based distribution on a 1.9 GB live DVD with a large number of applications, media codecs and custom artwork: "Hanthana Linux 28 (Kandula - Security Edition of Hanthana Linux pre-released) is released. Hanthana Linux 28 (Kandula - Security Edition of Hanthana Linux), the latest release of Hanthana part of the Hanthana Linux project. In addition to the host of applications, the new release has the official LibreOffice guide provided by The Document Foundation added as well. Please note there are various desktop editions including Gnome 3,Gnome Sugar,KDE,LXDE,XFCE. See also Linux User Group List of Linux distributions List of Fedora-based operating systems Computer technology for developing areas References External links Hanthana 19.0 Review: Sri Lankan spiced up Fedora, has some bugs but quite good in overall – An user review based on Hanthana Linux 19. Weekend Project: Linux Distros You Never Heard Of – Review on Linux[dot]com. Best Linux Distributions Based On Fedora – Review on itsfoss blog. Hanthana Linux on Channel Eye RiseNShine - TV Programme about Hanthana Linux on ChannelEye Open source opening doors to IT - Danishka Navin speaks to the Mirror about revolutionizing IT needs among those in the outstations with open source software Hanthana Community - Hanthana Linux Support Group RPM-based Linux distributions X86-64 Linux distributions Linux distributions

Operating System (OS)

Bharat Operating System Solutions Bharat Operating System Solutions (BOSS GNU/Linux) is an Indian Linux distribution derived from Debian. BOSS Linux is officially released in four editions: BOSS Desktop (for personal use, home and office), EduBOSS (for schools and education community), BOSS Advanced Server and BOSS MOOL. The latest stable version 8.0 ("Unnati"), was released on 11 July 2019. Development It is developed by Centre for Development of Advanced Computing (C-DAC) in order for enhancing and gain benefit from the usage of Free and Open Source Software throughout India. BOSS Linux is a key deliverable of National Resource Centre for Free and Open Source Software (NRC-FOSS). It has enhanced desktop environment integrated with Indian language support and other software. The software has been endorsed by the Government of India for adoption and implementation on a national scale. BOSS Linux is an "LSB certified" Linux distribution. The software has been certified by the Linux Foundation for compliance with the Linux Standard Base (LSB) standard. It supports Intel and AMD IA-32/x86-64 architecture till version 6. From version 7, the development shifted to x86-64 architecture only. Uses As of 2019, very few institutions and individuals in India use BOSS. BOSS and LibreOffice is included in the school syllabus but only few schools teach these open source software to the students. Version history BOSS Linux has had seven major releases. BOSS 5.0 (Anokha) This release came with many new applications mainly focused on enhanced security and user friendliness. The distribution includes over 12,800 new packages, for a total of over packages. Most of the software in the distribution has been updated: over software packages (this is 70% of all packages in Savir). BOSS 5.0 supports Linux Standard Base (LSB) version 4.1. The new version features XBMC to allow the user to easily browse and view videos, photos, podcasts, and music from a hard drive, optical disc, local network, and the internet. BOSS 6.0 (Anoop) There are several major updates in BOSS Linux 6.0 (Anoop) from 5.0 (Anokha). Notable changes include a kernel update from 3.10 to 3.16, a shift for system boot from init to systemd, the full support of GNOME Shell as part of GNOME 3.14, an update to the GRUB version, Iceweasel being replaced by Firefox and Pidgin replacing Empathy, and several repository versions of available programs being updated as part of the release. BOSS Linux 6.0 also shipped with various application and program updates, such as updates to LibreOffice, X.Org, Evolution, GIMP, VLC media player, GTK+, GCC, GNOME Keyring, and Python. Related specifically to the localisation support, language support got even better with the replacement of SCIM with IBus with the Integrated System Settings. Now Indic languages enabled with ″Region and Languages″ are directly mapped to the IBus and the OnScreenKeyboard layout is provided for all layouts. This release is fully compatible with LSB 4.1. BOSS 7.0 (Drishti) Biggest change over previous releases is that support for x86 version has been dropped and now it is only available for x86-64. Other noticeable changes include a linux kernel update to 4.9.0, GNOME update from 3.14 to 3.22 and software updates to various applications and programs with wide Indian language support & packages. This release aims more at enhancing the user interface with more glossy themes and is coupled with latest applications from the community. BOSS 8.0 (Unnati) Desktop Environment is changed from GNOME to Cinnamon. See also Debian Comparison of Linux distributions Free culture movement Simputer References External links 2007 software Debian-based distributions Language-specific Linux distributions Operating system distributions bootable from read-only media X86-64 Linux distributions Indic computing Urdu-language computing State-sponsored Linux distributions Linux distributions

Operating System (OS)

BeOS BeOS was an operating system for personal computers first developed by Be Inc. in 1990. It was first written to run on BeBox hardware. BeOS was positioned as a multimedia platform that could be used by a substantial population of desktop users and a competitor to Classic Mac OS and Microsoft Windows. It was ultimately unable to achieve a significant market share, and did not prove commercially viable for Be Inc. The company was acquired by Palm Inc. and today BeOS is mainly used and developed by a small population of enthusiasts. The open-source operating system Haiku is an open-source continuation of BeOS concepts. Beta 1 of Haiku was released in September 2018, six years after Alpha 4. Beta 2 of Haiku was released in June 2020, while Beta 3 was released about a year later in July 2021. History Initially designed to run on AT&T Hobbit-based hardware, BeOS was later modified to run on PowerPC-based processors: first Be's own systems, later Apple Inc.'s PowerPC Reference Platform and Common Hardware Reference Platform, with the hope that Apple would purchase or license BeOS as a replacement for its aging Classic Mac OS. Toward the end of 1996, Apple was still looking for a replacement to Copland in their operating system strategy. Amidst rumours of Apple's interest in purchasing BeOS, Be wanted to increase their user base, to try to convince software developers to write software for the operating system. Be courted Macintosh clone vendors to ship BeOS with their hardware. Apple CEO Gil Amelio started negotiations to buy Be Inc., but negotiations stalled when Be CEO Jean-Louis Gassée wanted $300 million; Apple was unwilling to offer any more than $125 million. Apple's board of directors decided NeXTSTEP was a better choice and purchased NeXT in 1996 for $429 million, bringing back Apple co-founder Steve Jobs. In 1997, Power Computing began bundling BeOS (on a CD for optional installation) with its line of PowerPC-based Macintosh clones. These systems could dual boot either the Classic Mac OS or BeOS, with a start-up screen offering the choice. Motorola also announced in February 1997 that it would bundle BeOS with their Macintosh clones, the Motorola StarMax, along with MacOS. Due to Apple's moves and the mounting debt of Be Inc., BeOS was soon ported to the Intel x86 platform with its R3 release in March 1998. Through the late 1990s, BeOS managed to create a niche of followers, but the company failed to remain viable. Be Inc. also released a stripped-down, but free, copy of BeOS R5 known as BeOS Personal Edition (BeOS PE). BeOS PE could be started from within Microsoft Windows or Linux, and was intended to nurture consumer interest in its product and give developers something to tinker with. Be Inc. also released a stripped-down version of BeOS for Internet Appliances (BeIA), which soon became the company's business focus in place of BeOS. In 2001 Be's copyrights were sold to Palm, Inc. for some $11 million. BeOS R5 is considered the last official version, but BeOS R5.1 "Dano", which was under development before Be's sale to Palm and included the BeOS Networking Environment (BONE) networking stack, was leaked to the public shortly after the company's demise. In 2002, Be Inc. sued Microsoft claiming that Hitachi had been dissuaded from selling PCs loaded with BeOS, and that Compaq had been pressured not to market an Internet appliance in partnership with Be. Be also claimed that Microsoft acted to artificially depress Be Inc.'s initial public offering (IPO). The case was eventually settled out of court for $23.25 million with no admission of liability on Microsoft's part. After the split from Palm, PalmSource used parts of BeOS's multimedia framework for its failed Palm OS Cobalt product. With the takeover of PalmSource, the BeOS rights now belong to Access Co. Continuation and clones In the years that followed the demise of Be Inc. a handful of projects formed to recreate BeOS or key elements of the OS with the eventual goal of then continuing where Be Inc. left off. This was facilitated by Be Inc. having released some components of BeOS under a free licence. Such projects include: BlueEyedOS: It uses a modified version of the Linux kernel and reimplements the BeOS API over it (BeOS applications need to be recompiled). It is freely downloadable, but sources were never published. There have been no releases since 2003. Cosmoe: A port of the Haiku userland over a Linux kernel. BeOS applications need to be recompiled. It is free and open source software. The last release was in 2004 and its website is no longer online. E/OS: short for Emulator Operating System. A Linux and FreeBSD-based operating system that aimed to run Windows, DOS, AmigaOS and BeOS applications. It is free and open source software. Active development ended in July 2008. Haiku: A complete reimplementation of BeOS not based on Linux. Unlike Cosmoe and BlueEyedOS, it is directly compatible with BeOS applications. It is free and open source software. The first alpha release, "Haiku R1 / Alpha 1", was released on September 14, 2009. The second alpha release, "Haiku R1 / Alpha 2", was made available on May 9, 2010, and the third alpha release, "Haiku R1 / Alpha 3", on June 18, 2011. "Haiku R1 / Alpha 4" was released November 12, 2012. As of 2020, it is the only BeOS clone still under development, with the first beta version released on September 28, 2018, the second beta version released on June 9, 2020, and the third beta version released on July 26, 2021. Zeta was a commercially available operating system based on the BeOS R5.1 codebase. Originally developed by yellowTAB, the operating system was then distributed by magnussoft. During development by yellowTAB, the company received criticism from the BeOS community for refusing to discuss its legal position with regard to the BeOS codebase (perhaps for contractual reasons). Access Co. (which bought PalmSource, until then the holder of the intellectual property associated with BeOS) has since declared that yellowTAB had no right to distribute a modified version of BeOS, and magnussoft has ceased distribution of the operating system. Version history Features BeOS was built for digital media work and was written to take advantage of modern hardware facilities such as symmetric multiprocessing by utilizing modular I/O bandwidth, pervasive multithreading, preemptive multitasking and a 64-bit journaling file system known as BFS. The BeOS GUI was developed on the principles of clarity and a clean, uncluttered design. The API was written in C++ for ease of programming. The GUI was largely multithreaded: each window ran in its own thread, relying heavily on sending messages to communicate between threads; and these concepts are reflected into the API. It has partial POSIX compatibility and access to a command-line interface through Bash, although internally it is not a Unix-derived operating system. Many Unix applications were ported to the BeOS command-line interface. BeOS used Unicode as the default encoding in the GUI, though support for input methods such as bidirectional text input was never realized. Products using BeOS BeOS (and now Zeta) continue to be used in media appliances, such as the Edirol DV-7 video editors from Roland Corporation, which run on top of a modified BeOS and the Tunetracker Radio Automation software that used to run it on BeOS and Zeta, and it was also sold as a "Station-in-a-Box" with the Zeta operating system included. In 2015, Tunetracker released a Haiku distribution bundled with its broadcasting software. The Tascam SX-1 digital audio recorder runs a heavily modified version of BeOS that will only launch the recording interface software. The RADAR 24, RADAR V and RADAR 6, hard disk-based, 24-track professional audio recorders from iZ Technology Corporation were based on BeOS 5. Magicbox, a manufacturer of signage and broadcast display machines, uses BeOS to power their Aavelin product line. Final Scratch, a 12-inch vinyl timecode record-driven DJ software/hardware system, was first developed on BeOS. The "ProFS" version was sold to a few dozen DJs prior to the 1.0 release, which ran on a Linux virtual partition. See also Access Co. BeIA bootman Comparison of operating systems Gobe Productive Hitachi Flora Prius KDL NetPositive OpenTracker Pe References Further reading External links The Dawn of Haiku, by Ryan Leavengood, IEEE Spectrum May 2012, p 40–43,51-54. Mirror of the old www.be.com site Other Mirror of the old www.be.com site BeOS Celebrating Ten Years BeGroovy A blog dedicated to all things BeOS BeOS: The Mac OS X might-have-been, reghardware.co.uk Programming the Be Operating System: An O'Reilly Open Book (out of print, but can be downloaded) (BeOS) Discontinued operating systems Object-oriented operating systems PowerPC operating systems X86 operating systems

Operating System (OS)

Windows Embedded Compact Windows Embedded Compact, formerly Windows Embedded CE, Windows Powered and Windows CE, is an operating system subfamily developed by Microsoft as part of its Windows Embedded family of products. Its mainstream support ended in 2018, and "extended support" will end in 2023. Unlike Windows Embedded Standard, which is based on Windows NT, Windows Embedded Compact uses a different hybrid kernel. Microsoft licenses it to original equipment manufacturers (OEMs), who can modify and create their own user interfaces and experiences, with Windows Embedded Compact providing the technical foundation to do so. The current version of Windows Embedded Compact supports x86 and ARM processors with board support package (BSP) directly. The MIPS and SHx architectures had support prior to version 7.0. 7.0 still works on MIPSII architecture. Originally, Windows CE was designed for minimalistic and small computers. However CE had its own kernel whereas those such as Windows XP Embedded are based on NT. Windows CE was a modular/componentized operating system that served as the foundation of several classes of devices such as Handheld PC, Pocket PC, Auto PC, Windows Mobile, Windows Phone 7 and more. Features Windows CE is optimized for devices that have minimal memory; a Windows CE kernel may run with one megabyte of memory. Devices are often configured without disk storage, and may be configured as a "closed" system that does not allow for end-user extension (for instance, it can be burned into ROM). Windows CE conforms to the definition of a real-time operating system, with a deterministic interrupt latency. From Version 3 and onward, the system supports 256 priority levels and uses priority inheritance for dealing with priority inversion. The fundamental unit of execution is the thread. This helps to simplify the interface and improve execution time. The first version known during development under the code name "Pegasus" featured a Windows-like GUI and a number of Microsoft's popular apps, all trimmed down for smaller storage, memory, and speed of the palmtops of the day. Since then, Windows CE has evolved into a component-based, embedded, real-time operating system. It is no longer targeted solely at hand-held computers. Many platforms have been based on the core Windows CE operating system, including Microsoft's AutoPC, Pocket PC 2000, Pocket PC 2002, Windows Mobile 2003, Windows Mobile 2003 SE, Windows Mobile 5, Windows Mobile 6, Smartphone 2002, Smartphone 2003, Portable Media Center, Zune, Windows Phone 7 and many industrial devices and embedded systems. Windows CE even powered select games for the Sega Dreamcast and was the operating system of the Gizmondo handheld. A distinctive feature of Windows CE compared to other Microsoft operating systems is that large parts of it are offered in source code form. First, source code was offered to several vendors, so they could adjust it to their hardware. Then products like Platform Builder (an integrated environment for Windows CE OS image creation and integration, or customized operating system designs based on CE) offered several components in source code form to the general public. However, a number of core components that do not need adaptation to specific hardware environments (other than the CPU family) are still distributed in binary only form. Windows CE 2.11 was the first embedded Windows release to support a console and a Windows CE version of . History Windows Embedded Compact was formerly known as Windows CE. According to Microsoft, "CE" is not an explicit acronym for anything, although it implies a number of notions that Windows developers had in mind, such as "compact", "connectable", "compatible", "companion" and "efficient". The name changed once in 2006, with the release of Windows Embedded CE 6.0, and again in 2011, with the release of Windows Embedded Compact 7. Windows CE was originally announced by Microsoft at the COMDEX expo in 1996 and was demonstrated on stage by Bill Gates and John McGill. Microsoft had been testing Pegasus in early 1995 and released a strict reference platform to several hardware partners. The devices had to have the following minimum hardware specifications: SH3, MIPS 3000 or MIPS 4000 CPU Minimum of 4 MB of ROM Minimum of 2 MB of RAM with a backup power source, such as a CR2032 coin cell battery Powered by two AA batteries Weigh less than 1 lbs A physical QWERTY keyboard including Ctrl, Alt and Shift keys An LCD display of 480×240 pixels with four shades of gray and two bits per pixel with touchscreen that could be operated by either stylus or finger An Infrared transceiver Serial port PC Card slot Built in speaker Devices of the time mainly had 480×240 pixel displays with the exception of the Hewlett-Packard 'Palmtop PC' which had a 640×240 display. Each window took over the full display. Navigation was done by tapping or double tapping on an item. A contextual menu was also available by the user pressing the ALT key and tapping on the screen. Windows CE 1.0 did not include a cascading Start menu unlike Windows 95 and Windows NT 4.0 did. Microsoft released the Windows CE 1.0 Power Toys that included a cascading menu icon that appeared in the system tray. Also bundled were several other utilities, most notable were a sound applet for the system tray, enabling the user to quickly mute or unmute their device or adjust the volume and a 'pocket' version of Paint. The release of Windows CE 2.0 was well received. Microsoft learned its lessons from consumer feedback of Windows CE 1.0 and made many improvements to the operating system. The Start menu was a cascading menu, identical to those found on Windows 95 and Windows NT 4.0. Color screens were also supported and manufacturers raced to release the first color H/PC. The first to market however, was Hewlett Packard with the HP 620LX. Windows CE 2.0 also supported a broader range of CPU architectures. Programs could be also installed directly in the OS by double clicking on CAB files. Due to the nature of the ROMs that contained the operating system, users were not able to flash their devices with the newer operating system. Instead manufacturers released upgrade ROMs that users had to physically install in their devices, after removing the previous version. This would usually wipe the data on the device and present the user with the setup wizard upon first boot. In November 1999, it was reported that Microsoft was planning to rename Windows CE to Windows Powered. The name only appeared in brand in Handheld PC 2000 and a build of Windows 2000 Advanced Server (which bears no relation to Windows CE). Various Windows CE 3.0 products announced at CES 2001 were marketed under a "Windows Powered" umbrella name. Development tools Visual Studio Microsoft Visual Studio 2012, 2013, and 2015 support apps and Platform Builder development for Windows Embedded Compact 2013. Microsoft Visual Studio 2008 and earlier support projects for older releases of Windows CE/Windows Mobile, producing executable programs and platform images either as an emulator or attached by cable to an actual mobile device. A mobile device is not necessary to develop a CE program. The .NET Compact Framework supports a subset of the .NET Framework with projects in C#, and Visual Basic .NET, but not Managed C++. "Managed" apps employing the .NET Compact Framework also require devices with significantly larger memories (8 MB or more) while unmanaged apps can still run successfully on smaller devices. In Visual Studio 2010, the Windows Phone Developer Tools are used as an extension, allowing Windows Phone 7 apps to be designed and tested within Visual Studio. Free Pascal and Lazarus Free Pascal introduced the Windows CE port in Version 2.2.0, targeting ARM and x86 architectures. Later, the Windows CE header files were translated for use with Lazarus, a rapid application development (RAD) software package based on Free Pascal. Windows CE apps are designed and coded in the Lazarus integrated development environment (IDE) and compiled with an appropriate cross compiler. Platform Builder This programming tool is used for building the platform (BSP + Kernel), device drivers (shared source or custom made) and also the apps. This is a one stop environment to get the system up and running. One can also use Platform Builder to export an SDK (software development kit) for the target microprocessor (SuperH, x86, MIPS, ARM etc.) to be used with another associated tool set named below. Others The Embedded Visual C++ (eVC) a tool for development of embedded apps for Windows CE. It can be used standalone using the SDK exported from Platform Builder or using the Platform Builder's Platform Manager connectivity setup. CeGcc project provides GNU development tools, such as GNU C, GNU C++ and binutils that targeting Windows CE; 2 SDKs are available to choose from a standard Windows CE platform SDK based on MinGW, and a newlib-based SDK which may be easier for porting programs from POSIX systems. CodeGear Delphi Prism runs in Visual Studio, also supports the .NET Compact Framework and thus can be used to develop mobile apps. It employs the Oxygene compiler created by RemObjects Software, which targets .NET, the .NET Compact Framework, and Mono. Its command-line compiler is available free of charge. Basic4ppc a programming language similar to Visual Basic, targets the .NET Compact Framework and supports Windows CE and Windows Mobile devices. GLBasic a very easy to learn and use BASIC dialect that compiles for many platforms, including Windows CE and Windows Mobile. It can be extended by writing inline C/C++ code. LabVIEW a graphical programming language, supporting many platforms, including Windows CE. MortScript is the semi-standard, extremely lightweight, automation SDK popular with the GPS enthusiasts. Uses the scripts written in its own language, with the syntax being aside to VBScript or JScript. AutoHotkey a port of the open source macro-creation and automation software utility available for Windows CE. It allows the construction of macros and simple GUI apps developed by systems analyst Jonathan Maxian Timkang. Relationship to Windows Mobile, Pocket PC, and SmartPhone Often Windows CE, Windows Mobile, and Pocket PC are used interchangeably, in part due to their common origin. This practice is not entirely accurate. Windows CE is a modular/componentized operating system that serves as the foundation of several classes of devices. Some of these modules provide subsets of other components' features (e.g. varying levels of windowing support; DCOM vs COM), others which are separate (bitmap or TrueType font support), and others which add additional features to another component. One can buy a kit (the Platform Builder) which contains all these components and the tools with which to develop a custom platform. Apps such as Excel Mobile (formerly Pocket Excel) are not part of this kit. The older Handheld PC version of Pocket Word and several other older apps are included as samples, however. Windows Mobile is best described as a subset of platforms based on a Windows CE underpinning. Currently, Pocket PC (now called Windows Mobile Classic), SmartPhone (Windows Mobile Standard), and Pocket PC Phone Edition (Windows Mobile Professional) are the three main platforms under the Windows Mobile umbrella. Each platform uses different components of Windows CE, plus supplemental features and apps suited for their respective devices. Pocket PC and Windows Mobile are Microsoft-defined custom platforms for general PDA use, consisting of a Microsoft-defined set of minimum profiles (Professional Edition, Premium Edition) of software and hardware that is supported. The rules for manufacturing a Pocket PC device are stricter than those for producing a custom Windows CE-based platform. The defining characteristics of the Pocket PC are the touchscreen as the primary human interface device and its extremely portable size. CE v3.0 is the basis for Pocket PC 2002. A successor to CE v3.0 is CE.net. "PocketPC [is] a separate layer of code on top of the core Windows CE OS... Pocket PC is based on Windows CE, but it's a different offering." And licensees of Pocket PC are forbidden to modify the WinCE part. The SmartPhone platform is a feature-rich OS and interface for cellular phone handsets. SmartPhone offers productivity features to business users, such as email, and multimedia abilities for consumers. The SmartPhone interface relies heavily on joystick navigation and PhonePad input. Devices running SmartPhone do not include a touchscreen interface. SmartPhone devices generally resemble other cellular handset form factors, whereas most Phone Edition devices use a PDA form factor with a larger display. Releases See also ActiveSync Handheld PC Handheld PC Explorer List of Windows CE Devices Microsoft Kin Modular Windows Palm-size PC Pocket PC Portable Media Center Tablet PC Windows Phone Zune HD Dreamcast References External links Benchmarking Real-time Determinism in Microsoft Windows CE A Brief History of Windows CE, by HPC:Factor with screenshots of the various versions , Archived copy of website hosted by Handheld PC Windows XP Embedded on MSDN Mike Hall's Windows Embedded Blog Windows CE ARM operating systems 1996 software

Operating System (OS)

Standard Operating Environment A standard operating environment (SOE) is a standard implementation of an operating system and its associated software. Associated names and concepts include: Managed operating environment (MOE) Consistent or common operating environment (COE) Managed desktop environment (MDE) Desktop managed services (DMS) Standard desktop environment (SDE) Standard desktop configuration (SDC) Unmanaged operating environment (UOE) "Standard image" Administrators typically implement SOE as a standard disk image for mass deployment to multiple computers in an organisation, to ultimately set security controls and increase the security posture of an environment. SOEs can include the base operating system, a custom configuration, standard applications used within an organisation, software updates and service packs. An SOE can apply to servers, desktops, laptops, thin clients, and mobile devices. The major advantage of an SOE in a business environment is the reduction in the cost and time taken to deploy, configure, maintain, support and manage computers. By standardising the hardware and software platforms used within an organization, an IT department or service provider can deploy new computers and correct problems with existing computers quickly. A standardized, repeatable and automated solution creates a known, expected and supportable environment. A standardised solution ensures maintaining known outcomes, with automation fostering speed, repeatability and standardization. The introduction of bring-your-own-device (BYOD) and the significant increase in employee-supplied devices has led many organisations to reconsider the use of an SOE. A number have implemented an unmanaged operating environment where users manage and maintain their own devices, subject to policies enforcing minimum standards. Examples There are many Windows deployment guides and tools available from Microsoft and other vendors. Many businesses endeavor to build their own SOE solutions using the Microsoft Business Desktop Deployment (BDD) solution accelerator or Microsoft Deployment Toolkit (MDT). However, some do not have the capability to build all features in one single SOE and their processes often include documented manual configuration steps. SOEs on Mac OS X, Linux, and other Unix/Unix-like systems can typically be made simply by creating and deploying disk images. This can be achieved using tools such as Disk Utility and dd. Whereas deploying a disk image originating from a system with non-identical hardware will often result in boot failure with Windows, the process is generally achievable on Unix systems with the caveat that the systems must be of the same computer architecture and drivers will need to be installed on the image for all the possible hardware configurations. Since Apple does not have third party computer manufacturers usually only hardware add-ons are a concern with respect to drivers. On Linux most hardware with kernel support can be auto-detected. Boot scripts can be used for automated post-deployment configuration. There are also a number of vendor-specific SOE systems for various Linux/Unix-like distributions. For Solaris the use of jumpstart scripts is more frequent to ease the automation of setting specific parameters for each system. In Red Hat Enterprise Linux this is typically done by using kickstart scripts, there are specific products to create and manage an SOE like Red Hat Network Satellite Server which avoid the disk space usage and maintenance difficulties of managing disk images. References impeltec SOE definition System administration

Operating System (OS)

T-Kernel T-Kernel is an open source real-time operating system (RTOS) designed for 32-bit microcontrollers. It is standardized by the T-Engine Forum, which distributes it under a T-License agreement. There is also a corresponding Micro T-Kernel (μT-Kernel) implementation designed for embedded systems with 16-bit or 8-bit microcontrollers. History In 1984 professor Ken Sakamura started The Real-time Operating system Nucleus (TRON project) at the University of Tokyo, with the goal of designing an open real-time operating system (RTOS) kernel. The TRON framework defines a complete architecture for the different computing units. Industrial TRON (ITRON) is the most popular TRON architecture. ITRON specification promotion was done by the various companies which sell the commercial implementations. T-Kernel is the name of the specification and at the same time a single implementation based on the authorized source code available from the T-Engine Forum for free under T-License. T-Engine is arguably the most advanced ubiquitous computing platform in the world. In 1989, Matsushita Electric Industrial Co., Ltd., now known as Panasonic Corporation, introduced a TRON PC. This personal computer had an Intel 80286 chip of 8 MHz and only 2 MB of memory, but it could display moving video. Also, it had a dual-booting system that could run both the TRON OS and DOS. Although the Japanese government once announced it would use the TRON PC in Japanese schools, the plan was dropped, partly due to economic issues with the United States. But ITRON survived, and today is used in many devices, household appliances, automobile electronics, robots, some satellites, and in factory automation systems in China. Embedded system developers claim that ITRON is the number one OS for embedded chips in both Japan and the United States. Overview To make it easy to distribute middleware, T-Kernel has separate specification for subsystem and device driver which will be suitable for different types of middleware APIs. A real-time OS appropriate for individual application can be created by combining the middleware called T-Kernel Extension with the T-Kernel. T-Monitor initializes computer hardware and handles the interrupt set up at the start. T-Monitor lessens hardware-dependency of T-Kernel, and improves the application portability. T-Kernel consists of the following three components from the viewpoint of function. T-Kernel/OS (operating system) This offers the basic functions as real-time Operating System. T-Kernel/SM (system manager) This offers the functions including system memory management function and address space management function in order to manage middleware such as device drivers and subsystems. T-Kernel/DS (debugger support) This offers the functions for debuggers to be used in development tools. Development environment eBinder from eSol Corporation is one commonly used integrated development environment (IDE) for software cross-development targeting T-Kernel. The current release of T-Kernel 2.0 is distributed with a plug-in for Eclipse IDE. Also, a version of T-Kernel that runs on QEMU based emulator, and the QEMU based emulator itself, are available so that testing, training, and development can be done on a PC without a target hardware. It is supported by popular SSL/TLS libraries such as wolfSSL. See also ThreadX References External links , TRON Forum Sakamura home page ITRON Project Archive Introducing the μT-Kernel Information about T-Engine, T-Kernel, and μT-Kernel Programming Embedded operating systems TRON project

Operating System (OS)

AmigaOS version history AmigaOS is the proprietary native operating system of the Amiga personal computer. Since its introduction with the launch of the Amiga 1000 in 1985, there have been four major versions and several minor revisions of the operating system. Initially the Amiga operating system had no strong name and branding, as it was simply considered an integral part of the Amiga system as a whole. Early names used for the Amiga operating system included "CAOS" and "AmigaDOS". Another non-official name was "Workbench", from the name of the Amiga desktop environment, which was included on a floppy disk named "Amiga Workbench". Version 3.1 of the Amiga operating system was the first version to be officially referred to as "Amiga OS" (with a space between "Amiga" and "OS") by Commodore. Version 4.0 of the Amiga operating system was the first version to be branded as a less generic "AmigaOS" (without the space). What many consider the first versions of AmigaOS (Workbench 1.0 up to 3.0) are here indicated with the Workbench name of their original disks. Kickstart/Workbench 1.0, 1.1, 1.2, 1.3 Workbench 1.0 was released for the first time in October 1985. The 1.x series of Workbench defaults to a distinctive blue and orange color scheme, designed to give high contrast on even the worst of television screens (the colors can be changed by the user). Version 1.1 consists mostly of bug fixes and, like version 1.0, was distributed only for the Amiga 1000. The entire Workbench operating system consisted of three floppy disks: Kickstart, Workbench and ABasic by MetaComCo. The Amiga 1000 needed a Kickstart disk to be inserted into floppy drive to boot up. An image of a simple illustration of a hand on a white screen, holding a blue Kickstart floppy, invited the user to perform this operation. After the kickstart was loaded into a special section of memory called the writable control store (WCS), the image of the hand appeared again, this time inviting the user to insert the Workbench disk. Workbench version 1.2 was the first to support Kickstart stored in a ROM. A Kickstart disk was still necessary for Amiga 1000 models; it was no longer necessary for Amiga 500 or 2000, but the users of these systems had to change the ROMs (which were socketed) to change the Kickstart version. Workbench now spanned two floppy disks, and supported installing and booting from hard drive (assuming the Amiga was equipped with one), the name of the main disk was still named "Workbench" (which is also the user interface portion of the operating system). The second disk was the Extras disk. The system now shipped with AmigaBasic by Microsoft, the only software Microsoft ever wrote for the Amiga. Kickstart version 1.2 corrected various flaws and added AutoConfig support. AutoConfig is a protocol similar to and is the predecessor of Plug and Play, in that it can configure expansion boards without user intervention. Kickstart version 1.3 improved little on its predecessor, the most notable change being auto booting from hard drives. Workbench 1.3, on the other hand, users can find several significant improvements to Workbench, including FFS a faster file system for hard disks storage which resolved the problem of old Amiga filesystem which wasted too much hard disk space due to the fact it could store only 488 bytes in any block of 512 bytes keeping 24 bytes for checksums. Many improvements were made to the CLI (command line interface) of Amiga which was now a complete text based Shell, named AmigaShell, and various additional tools and programs. Kickstart/Workbench 1.4 Kickstart/Workbench 1.4 was a beta version of the upcoming 2.0 update and never released, but the Kickstart part was shipped in very small quantities with early Amiga 3000 computers, where it is often referred to as the "Superkickstart ROM". In these machines it is only used to bootstrap the machine and load the Kickstart that will be used to actually boot the system. The appearance of a very early first release of 1.4 was similar to 1.3, but with colors slightly changed. A second version was similar to that of 2.0 and higher, with just minor differences. It is, however, possible to dump out of the OS selection screen by clicking where one would expect to see a close gadget. This will cause the machine to boot Kickstart 1.4 using either the wb_2.x: partition, or from a floppy. Workbench 2.0, 2.04, 2.05, 2.1 Workbench 2.0 was released in 1990 and introduced a lot of improvements and major advances to the GUI of the overall Amiga operating system. The harsh blue and orange colour scheme was replaced with a much easier on the eye grey and light blue with 3D aspect in the border of the windows. The Workbench was no longer tied to the 640×256 (PAL) or 640×200 (NTSC) display modes, and much of the system was improved with an eye to making future expansion easier. For the first time, a standardised "look and feel" was added. This was done by creating the Amiga Style Guide, and including libraries and software which assisted developers in making conformant software. Technologies included the GUI element creation library gadtools, the software installation scripting language Installer, and the AmigaGuide hypertext help system. Workbench 2.04 introduced ARexx, a system-wide scripting language. Programmers could add so-called "ARexx ports" to their programs, which allowed them to be controlled from ARexx scripts. Using ARexx, you could make two completely different programs from different vendors work together seamlessly. For example, you could batch-convert a directory of files to thumbnail images with an ARexx-capable image-manipulation program, create and index HTML table of the thumbnails linking to the original images, and display it in a web browser, all from one script. ARexx became very popular, and was widely adopted by programmers. The AmigaDOS, previously written in BCPL and very difficult to develop for beyond basic file manipulation, was mostly rewritten in C. Unfortunately, some badly written software – especially games – failed to run with 2.x, and so a lot of people were upset with this update. Most often, the failure occurred because programmers had used directly manipulated private structures maintained by the operating system, rather than using official function calls. Many users circumvented the problem by installing so-called "kickstart switchers", a small circuit board which held both a Kickstart 1.3 and 2.0 chip, with which they could switch between Kickstart versions. 2.x shipped with the A500+ (2.04), A600 (2.05), A3000 and A3000T. Workbench 2.1 was the last in this series, and only released as a software update. It included useful features such as CrossDOS, to support working with floppy disks formatted for PCs. Since 2.1 was a software-only release, there was no Kickstart 2.1 ROM. 2.x also introduced PCMCIA card support, for the slot on the A600. Workbench 2.1 introduced also a standard hypertext markup language for easily building guides for the user or help files, or manuals. It was called AmigaGuide. Release 2.1 was also the first Workbench release to feature a system-standard localization system, allowing the user to make an ordered list of preferred languages; when a locale-aware application runs, it asks the operating system to find the catalog (a file containing translations of the application's strings) best matching the user's preferences. Amiga OS 3.0, 3.1 Amiga OS 3.0 was released in 1992 and version 3.1 between 1993 (for the CD32) and 1994 (for other Amiga models). Amiga OS 3.1 was the last version released by Commodore. The 3.x series added support for new Amiga models. Other new features included: A universal data system, known as DataTypes, that allowed programs to load pictures, sound, text and other content in formats they didn't understand directly, through the use of standard plugs (see object-oriented operating system) (3.0) Better color remapping for high-color display modes and support for the new AGA chipset. (3.0) Improved visual appearance for Workbench desktop. (3.0) CD-ROM support as required for Amiga CD32. (3.1) 3.x shipped with the CD32, A1200, A4000 and A4000T. AmigaOS 3.1.4, 3.2 AmigaOS 3.1.4 was released in September 2018 by Hyperion Entertainment with many fixes and enhancements. In particular, support of larger hard drives including at bootup; the entire line of Motorola 680x0 CPUs up to (and including) the Motorola 68060; and a modernized Workbench with a new, optional icon set. The version number caused some confusion in the community as it was released after AmigaOS 3.5, 3.9, and even 4.x, but relates to the fact that the codebase is a clean slate building from the original 3.1 source code from Commodore. The source code for both 3.5 and 3.9 by Haage & Partner could not legally be used due to licensing reasons, and 4.x is built and reserved for the PowerPC platform. Unlike AmigaOS 3.5, AmigaOS 3.1.4 still supports the Motorola 68000 CPU, thus the complete range of classic Amiga computers. In May 2021, Hyperion Entertainment released AmigaOS 3.2, which includes all features of the previous version (3.1.4.1) and adds several new improvements such as support for ReAction GUI, management of Amiga Disk File images, help system and improved datatypes. AmigaOS 3.5, 3.9 After the demise of Commodore, Workbench 3.5 was released on 18 October 1999 and Workbench 3.9 in December 2000 by German company Haage & Partner, which was granted the license to update the Amiga operating system by its new owners. Whereas all previous OS releases ran on Motorola 68000, AmigaOS 3.5 onwards required a 68020 or better, CD-ROM and at least 4 MB RAM. Unlike previous releases, 3.5 and 3.9 were released on CD-ROM. Kickstart 3.1 was also required, as the operating system didn't include the new ROM. Updates included: Supplied with TCP/IP stack (unregistered time-limited free MiamiDX demo in 3.5, unrestricted AmiTCP in 3.9), web browser (AWeb), and e-mail client Improved GUI and new toolkit called "ReAction" AVI/MPEG movie player (OS3.9) New partitioning software to support hard disks larger than 4 GB HTML documentation in English and German MP3 and CD audio player (OS3.9) Dock program (OS3.9) Improved Workbench with asynchronous features Find utility (OS3.9) Unarchiving system called XAD (OS3.9) WarpOS PowerPC kernel to support PowerUP accelerator boards AmigaOS 4 A new version of AmigaOS was released on December 24, 2006 after five years of development by Hyperion Entertainment (Belgium) under license from Amiga, Inc. for AmigaOne registered users. During the five years of development, users of AmigaOne machines could download from Hyperion repository Pre-Release Versions of AmigaOS 4.0 as long as these were made available. As witnessed by many users into Amiga discussion forum sites, these versions were stable and reliable, despite the fact that they are technically labeled as "pre-releases". Last stable version of AmigaOS 4.0 for AmigaOne computers is the "July 2007 Update", released for download 18 July 2007 to the registered users of AmigaOne machines. AmigaOS 4 Classic was released commercially for older Amiga computers with CyberstormPPC and BlizzardPPC accelerator cards in November 2007. It had previously been available only to developers and beta-testers. Version 4.0 The new version is PowerPC-native, finally abandoning the Motorola 68k processor. AmigaOS 4.0 will run on some PowerPC hardware, which currently only includes A1200, A3000 and A4000 with PowerPC accelerator boards and AmigaOne motherboards. Amiga, Inc.'s distribution policies for AmigaOS 4.0 and any later versions require that for third-party hardware the OS must be bundled with it, with the sole exception of Amigas with Phase 5 PowerPC accelerator boards, for which the OS will be sold separately. AmigaOS 4.0 Final introduced a new memory system based on the slab allocator. Features, among others: Fully skinnable GUI Virtualized memory Integrated viewer for PDF and other document formats Support for PowerPC (native) and 68k (interpreted/JIT) applications New drivers for various hardware New memory allocation system Support for file sizes larger than 2 GB Integrated Picasso 96 2D Graphics API Integrated Warp3D 3D Graphics API Version 4.1 AmigaOS 4.1 was presented to the public July 11, 2008, and went on sale September 2008. This is a new version and not only a simple update as it features, among others: Memory paging JXFS filesystem with the support for drives and partitions of multiple terabyte size Hardware compositing engine (Radeon R1xx and R2xx family) Implementation of the Cairo device-independent 2D rendering library New and improved DOS functionality (full 64 bit support, universal notification support, automatic expunge and reload of updated disk resources) Improved 3D hardware accelerated screen-dragging See also Kickstart versions References AmigaOS First Update Release announcement at Hyperion site. AmigaOS new memory system revisited article on OS4.Hyperion site AmigaOS new system for allocating memory article on OS4.Hyperion site AmigaOS 4.0 image included in this article is intended for fair use. In the past, neither Hyperion VOF (Belgium), nor Amiga Inc. (USA) were opposed to publishing in internet sites of AmigaOS 4.0 screenshots kindly donated by users. Owners of copyrights are free to register and write in the talk page of this article to ask for the removing of this image from article, and to ask also for its deletion. Hyperion Entertainment announces Amiga OS 4.1 AmigaOS Software version histories

Operating System (OS)

NOS/VE NOS/VE (Network Operating System / Virtual Environment) is a discontinued operating system with time-sharing capabilities, written by Control Data Corporation in the 1980s. It is a virtual memory operating system, employing the 64-bit virtual mode of the CDC Cyber 180 series computers. NOS/VE replaced the earlier NOS and NOS/BE operating systems of the 1970s. Commands The command shell interface for NOS/VE is called the System Command Language, or SCL for short. In order to be callable from SCL, command programs must declare their parameters; this permits automatic usage summaries, passing of parameters by name or by position, and type checking on the parameter values. All standard NOS/VE commands further follow a particular naming convention, where the form of the command is verb{_adjective}_noun; these commands could be abbreviated with the first three characters of the verb followed by the first character(s) of all further words. Examples: Inspired by addressing structure-members in various programming languages, the catalog separator is the dot. Subsystems like FTP integrate into the command shell. They change the prompt and add commands like get_file. Thereby statements like flow-control stay the same and subsystems can be mixed in procedures (scripts). Parameters Commands could take parameters such as the create_connection command: crec telnet sd='10.1.2.3' would connect you to IP address 10.1.2.3 with telnet service. See also NOS CDC Kronos NOS/BE External links User's Guide for NOS/VE on the CDC Cyber 960 Computer history - NOS/VE (Most of this information was extracted from a CDC NOS/VE information leaflet) NOS/VE Operating System NOS/VE Command Language Syntax List of NOS/VE Commands NOS/VE Utilities CDC operating systems Discontinued operating systems Time-sharing operating systems

Operating System (OS)

UNIX System V Unix System V (pronounced: "System Five") is one of the first commercial versions of the Unix operating system. It was originally developed by AT&T and first released in 1983. Four major versions of System V were released, numbered 1, 2, 3, and 4. System V Release 4 (SVR4) was commercially the most successful version, being the result of an effort, marketed as Unix System Unification, which solicited the collaboration of the major Unix vendors. It was the source of several common commercial Unix features. System V is sometimes abbreviated to SysV. , the AT&T-derived Unix market is divided between four System V variants: IBM's AIX, Hewlett Packard Enterprise's HP-UX and Oracle's Solaris, plus the free-software illumos forked from OpenSolaris. Overview Introduction System V was the successor to 1982's UNIX System III. While AT&T developed and sold hardware that ran System V, most customers ran a version from a reseller, based on AT&T's reference implementation. A standards document called the System V Interface Definition outlined the default features and behavior of implementations. AT&T support During the formative years of AT&T's computer business, the division went through several phases of System V software groups, beginning with the Unix Support Group (USG), followed by Unix System Development Laboratory (USDL), followed by AT&T Information Systems (ATTIS), and finally Unix System Laboratories (USL). Rivalry with BSD In the 1980s and early-1990s, UNIX System V and the Berkeley Software Distribution (BSD) were the two major versions of UNIX. Historically, BSD was also commonly called "BSD Unix" or "Berkeley Unix". Eric S. Raymond summarizes the longstanding relationship and rivalry between System V and BSD during the early period: While HP, IBM and others chose System V as the basis for their Unix offerings, other vendors such as Sun Microsystems and DEC extended BSD. Throughout its development, though, System V was infused with features from BSD, while BSD variants such as DEC's Ultrix received System V features. AT&T and Sun Microsystems worked together to merge System V with BSD-based SunOS to produce Solaris, one of the primary System V descendants still in use today. Since the early 1990s, due to standardization efforts such as POSIX and the success of Linux, the division between System V and BSD has become less important. Releases SVR1 System V, known inside Bell Labs as Unix 5.0, succeeded AT&T's previous commercial Unix called System III in January, 1983. Unix 4.0 was never released externally, which would have been designated as System IV. This first release of System V (called System V.0, System V Release 1, or SVR1) was developed by AT&T's UNIX Support Group (USG) and based on the Bell Labs internal USG UNIX 5.0. System V also included features such as the vi editor and curses from 4.1 BSD, developed at the University of California, Berkeley; it also improved performance by adding buffer and inode caches. It also added support for inter-process communication using messages, semaphores, and shared memory, developed earlier for the Bell-internal CB UNIX. SVR1 ran on DEC PDP-11 and VAX minicomputers. SVR2 AT&T's UNIX Support Group (USG) transformed into the UNIX System Development Laboratory (USDL), which released System V Release 2 in 1984. SVR2 added shell functions and the SVID. SVR2.4 added demand paging, copy-on-write, shared memory, and record and file locking. The concept of the "porting base" was formalized, and the DEC VAX-11/780 was chosen for this release. The "porting base" is the so-called original version of a release, from which all porting efforts for other machines emanate. Educational source licenses for SVR2 were offered by AT&T for US$800 for the first CPU, and $400 for each additional CPU. A commercial source license was offered for $43,000, with three months of support, and a $16,000 price per additional CPU. Apple Computer's A/UX operating system was initially based on this release. SCO XENIX also used SVR2 as its basis. The first release of HP-UX was also an SVR2 derivative. Maurice J. Bach's book, The Design of the UNIX Operating System, is the definitive description of the SVR2 kernel. SVR3 AT&T's UNIX System Development Laboratory (USDL) was succeeded by AT&T Information Systems (ATTIS), which distributed UNIX System V, Release 3, in 1987. SVR3 included STREAMS, Remote File Sharing (RFS), the File System Switch (FSS) virtual file system mechanism, a restricted form of shared libraries, and the Transport Layer Interface (TLI) network API. The final version was Release 3.2 in 1988, which added binary compatibility to Xenix on Intel platforms (see Intel Binary Compatibility Standard). User interface improvements included the "layers" windowing system for the DMD 5620 graphics terminal, and the SVR3.2 curses libraries that offered eight or more color pairs and other at this time important features (forms, panels, menus, etc.). The AT&T 3B2 became the official "porting base." SCO UNIX was based upon SVR3.2, as was ISC 386/ix. Among the more obscure distributions of SVR3.2 for the 386 were ESIX 3.2 by Everex and "System V, Release 3.2" sold by Intel themselves; these two shipped "plain vanilla" AT&T's codebase. IBM's AIX operating system is an SVR3 derivative. SVR4 System V Release 4.0 was announced on October 18, 1988 and was incorporated into a variety of commercial Unix products from early 1989 onwards. A joint project of AT&T Unix System Laboratories and Sun Microsystems, it combined technology from: SVR3 4.3BSD Xenix SunOS New features included: From BSD: TCP/IP support, sockets, UFS, support for multiple groups, C shell. From SunOS: the virtual file system interface (replacing the File System Switch in System V release 3), NFS, new virtual memory system including support for memory mapped files, an improved shared library system based on the SunOS 4.x model, the OpenWindows GUI environment, External Data Representation (XDR) and ONC RPC. From Xenix: x86 device drivers, binary compatibility with Xenix (in the x86 version of System V). KornShell. ANSI X3J11 C compatibility. Multi-National Language Support (MNLS). Better internationalization support. An application binary interface (ABI) based on Executable and Linkable Format (ELF). Support for standards such as POSIX and X/Open. Many companies licensed SVR4 and bundled it with computer systems such as workstations and network servers. SVR4 systems vendors included Atari (Atari System V), Commodore (Amiga Unix), Data General (DG/UX), Fujitsu (UXP/DS), Hitachi (HI-UX), Hewlett-Packard (HP-UX), NCR (Unix/NS), NEC (EWS-UX, UP-UX, UX/4800, SUPER-UX), OKI (OKI System V), Pyramid Technology (DC/OSx), SGI (IRIX), Siemens (SINIX), Sony (NEWS-OS), Sumitomo Electric Industries (SEIUX), and Sun Microsystems (Solaris) with illumos in the 2010s as the only open-source platform. Software porting houses also sold enhanced and supported Intel x86 versions. SVR4 software vendors included Dell (Dell UNIX), Everex (ESIX), Micro Station Technology (SVR4), Microport (SVR4), and UHC (SVR4). The primary platforms for SVR4 were Intel x86 and SPARC; the SPARC version, called Solaris 2 (or, internally, SunOS 5.x), was developed by Sun. The relationship between Sun and AT&T was terminated after the release of SVR4, meaning that later versions of Solaris did not inherit features of later SVR4.x releases. Sun would in 2005 release most of the source code for Solaris 10 (SunOS 5.10) as the open-source OpenSolaris project, creating, with its forks, the only open-source (albeit heavily modified) System V implementation available. After Oracle took over Sun, Solaris was forked into proprietary release, but illumos as the continuation project is being developed in open-source. A consortium of Intel-based resellers including Unisys, ICL, NCR Corporation, and Olivetti developed SVR4.0MP with multiprocessing capability (allowing system calls to be processed from any processor, but interrupt servicing only from a "master" processor). Release 4.1 ES (Enhanced Security) added security features required for Orange Book B2 compliance and Access Control Lists and support for dynamic loading of kernel modules. SVR4.2 / UnixWare In 1992, AT&T USL engaged in a joint venture with Novell, called Univel. That year saw the release System V.4.2 as Univel UnixWare, featuring the Veritas File System. Other vendors included UHC and Consensys. Release 4.2MP, completed late 1993, added support for multiprocessing and it was released as UnixWare 2 in 1995. Eric S. Raymond warned prospective buyers about SVR4.2 versions, as they often did not include on-line man pages. In his 1994 buyers guide, he attributes this change in policy to Unix System Laboratories. SVR5 / UnixWare 7 The Santa Cruz Operation (SCO), owners of Xenix, eventually acquired the UnixWare trademark and the distribution rights to the System V Release 4.2 codebase from Novell, while other vendors (Sun, IBM, HP) continued to use and extend System V Release 4. Novell transferred ownership of the Unix trademark to The Open Group. System V Release 5 was developed in 1997 by the Santa Cruz Operation (SCO) as a merger of SCO OpenServer (an SVR3-derivative) and UnixWare, with a focus on large-scale servers. It was released as SCO UnixWare 7. SCO's successor, The SCO Group, also based SCO OpenServer 6 on SVR5, but the codebase is not used by any other major developer or reseller. SVR6 (cancelled) System V Release 6 was announced by SCO to be released by the end of 2004, but was apparently cancelled. It was supposed to support 64-bit systems. SCO also discontinued Smallfoot in 2004. The industry has coalesced around The Open Group's Single UNIX Specification version 3 (UNIX 03). Market position Availability during the 1990s on x86 platforms In the 1980s and 1990s, a variety of SVR4 versions of Unix were available commercially for the x86 PC platform. However, the market for commercial Unix on PCs declined after Linux and BSD became widely available. In late 1994, Eric S. Raymond discontinued his PC-clone UNIX Software Buyer's Guide on USENET, stating, "The reason I am dropping this is that I run Linux now, and I no longer find the SVr4 market interesting or significant." In 1998, a confidential memo at Microsoft stated, "Linux is on track to eventually own the x86 UNIX market", and further predicted, "I believe that Linux – moreso than NT – will be the biggest threat to SCO in the near future." An InfoWorld article from 2001 characterized SCO UnixWare as having a "bleak outlook" due to being "trounced" in the market by Linux and Solaris, and IDC predicted that SCO would "continue to see a shrinking share of the market". Project Monterey Project Monterey was started in 1998 to combine major features of existing commercial Unix platforms, as a joint project of Compaq, IBM, Intel, SCO, and Sequent Computer Systems. The target platform was meant to be Intel's new IA-64 architecture and Itanium line of processors. However, the project was abruptly canceled in 2001 after little progress. System V and the Unix market By 2001, several major Unix variants such as SCO UnixWare, Compaq Tru64 UNIX, and SGI IRIX were all in decline. The three major Unix versions doing well in the market were IBM AIX, Hewlett-Packard's HP-UX, and Sun's Solaris. In 2006, when SGI declared bankruptcy, analysts questioned whether Linux would replace proprietary Unix altogether. In a 2006 article written for Computerworld by Mark Hall, the economics of Linux were cited as a major factor driving the migration from Unix to Linux: The article also cites trends in high-performance computing applications as evidence of a dramatic shift from Unix to Linux: In a November 2015 survey of the top 500 supercomputers, Unix was used by only 1.2% (all running IBM AIX), while Linux was used by 98.8%; the same survey in November 2017 reports 100% of them using Linux. System V derivatives continued to be deployed on some proprietary server platforms. The principal variants of System V that remain in commercial use are AIX (IBM), Solaris (Oracle), and HP-UX (HP). According to a study done by IDC, in 2012 the worldwide Unix market was divided between IBM (56%), Oracle (19.2%), and HP (18.6%). No other commercial Unix vendor had more than 2% of the market. Industry analysts generally characterize proprietary Unix as having entered a period of slow but permanent decline. OpenSolaris and illumos distributions OpenSolaris and its derivatives are the only SVR4 descendants that are open-source software. Core system software continues to be developed as illumos used in illumos distributions such as SmartOS, Omniosce, OpenIndiana and others. System V compatibility The System V interprocess communication mechanisms are available in Unix-like operating systems not derived from System V; in particular, in Linux (a reimplementation of Unix) as well as the BSD derivative FreeBSD. POSIX 2008 specifies a replacement for these interfaces. FreeBSD maintains a binary compatibility layer for the COFF format, which allows FreeBSD to execute binaries compiled for some SVR3.2 derivatives such as SCO UNIX and Interactive UNIX. Modern System V, Linux, and BSD platforms use the ELF file format for natively compiled binaries. References External links PC-clone UNIX Software Buyer's Guide by Eric S. Raymond (posted to USENET in 1994) Unix FAQ - history A Unix History Diagram - The original and continuously updated version of the Unix history, as published by O'Reilly Unix distributions 1983 software

Operating System (OS)

DOS (disambiguation) DOS is shorthand for the MS-DOS and IBM PC DOS family of operating systems. DOS may also refer to: Computing Data over signalling (DoS), multiplexing data onto a signalling channel Denial-of-service attack (DoS), an attack on a communications network Disk operating system List of disk operating systems, Apple DOS, Atari DOS, DOS/360, etc. Distributed operating system Music Albums Dos (Altered State album) Dos (Dos album) Dos (Fanny Lú album) Dos (Gerardo album) Dos (Malo album), 1972 Dos (Myriam Hernández album), 1989 Dos, album by Wooden Shjips, 2009 ¡Dos!, album by Green Day Other uses in music Dos (band), an American band DOS (concert), by Filipino singer Daniel Padilla Organisations Democratic Opposition of Serbia, a former political alliance Department of Space, India Deutscher Olympischer Sportbund Directorate of Overseas Surveys, UK 1957–1984 Dominus Obsequious Sororium, within cult NXIVM United States Department of State Places Dos, a village in Vidra Commune, Romania Science Density of states in physics DOS-1 etc., Russian space station designation in the Salyut programme Dioctyl sebacate, an organic chemical Diversity oriented synthesis in chemistry Sports DOS Kampen, a Dutch football club VV DOS, a past Dutch football club now part of FC Utrecht Other uses Dos (card game) Dos, an Ancient Roman dowry Day of Silence See also Doss (disambiguation)

Operating System (OS)

Hardware-dependent software Hardware-dependent software (HDS or HdS), the part of an operating system that varies across microprocessor boards and is comprised notably of device drivers and of boot code which performs hardware initialization. HDS does not comprise code which is only specific to a processor family and can run unchanged on various members of it. The HDS is alternatively called the BSP, for Board Support Package, especially in the world of commercial operating systems where the processor family code is distributed in binary form only. Often software that runs on operating systems may be hardware dependent at first, but emulators can reduce dependencies for specific hardware. See also Basic Input/Output System (BIOS) DeviceKit Embedded systems Firmware HAL (software) Hardware abstraction layer Machine-dependent software Programmable logic References Computing terminology

Operating System (OS)

Chromium OS Chromium OS is a free and open-source operating system designed for running web applications and browsing the World Wide Web. It is the open-source version of Chrome OS, a Linux distribution made by Google. Like Chrome OS, Chromium OS is based on the Linux kernel, but its principal user interface is the Chromium web browser rather than the Google Chrome browser. Chromium OS also includes the Portage package manager, which was originally developed for Gentoo Linux. Because Chromium OS and Chrome OS use a web browser engine for the user interface, they are oriented toward web applications rather than desktop applications or mobile apps. Google first published the Chromium OS source code in late 2009. Architecture Chromium's architecture is three-tiered, consisting of "three major components": The Chromium-based browser and the window manager System-level software and user-land services: the Linux kernel, drivers, connection manager, and so on Firmware Availability Chromium OS was first made available in compiled form by hobbyists. More organized efforts have emerged over time, including a few manufacturers that have shipped devices with the operating system pre-installed. Builds and forks By May 2010, compiled versions of the work-in-progress source code had been downloaded from the Internet more than a million times. The most popular version, entitled "Chromium OS Flow", was created by Liam McLoughlin, a then 17-year-old college student in Liverpool, England, posting under the name "Hexxeh". McLoughlin's build boots from a USB memory stick and included features that Google engineers had not yet implemented, such as support for the Java programming language. While Google did not expect that hobbyists would use and evaluate Chromium OS ahead of its official release, Sundar Pichai, Google's vice president of product management (now the CEO) said that "what people like Hexxeh are doing is amazing to see." Pichai said the early releases were an unintended consequence of open source development. "If you decide to do open-source projects, you have to be open all the way." Hexxeh's work continued into the following year. He announced "Chromium OS Lime" in December 2010, and in January 2011, released "Luigi", an application designed to "jailbreak"/"root" the Google Cr-48 "Mario" prototype hardware and install a generic BIOS. The developer made the builds available in virtual machine format on March 13, 2011. With no official build of Chromium OS forthcoming from Google, Hexxeh's "vanilla" nightly builds of Chromium OS were the principal resource for people wanting to try Chromium OS. Hexxeh stopped uploading his builds on April 20, 2013. More recent versions of Chromium OS are available from Arnoldthebat, who maintains daily and weekly builds along with usage guidelines and help. In July 2012, Chromium Build Kit was released. It automatically compiles a developer build and installs Chromium OS on a USB drive. In 2015, New York City-based Neverware produced a Chromium OS fork called CloudReady aimed at the educational market, with the intention of extending the life of older PCs and laptops. A subsequent version can dual-boot Neverware and the Windows operating system (until v64). In 2020, Neverware was acquired by Google, and a similar "Chrome OS Flex" was released into beta in February 2022. In 2016, Nexedi released NayuOS, a fork of Chromium OS precompiled for several Chromebook computers. The operating system provides Chrome OS-like capabilities without storing data on Google servers. It optionally removes the Google login and provides additional developer tools. Also in 2016, a London/Beijing-based startup produced a line of Chromium OS fork named Flint OS, targeting a wider range of platforms, including 64-bit PCs, Raspberry Pi, Tinker Board, Firefly development boards, and VMware virtual machines. The OS was later renamed Fyde OS. Hardware Some devices have shipped with Chromium OS preinstalled. In May 2011, Dell also released a new build for the Dell Inspiron Mini 10v netbook, following up on an earlier build released almost 18 months earlier. The build did not support audio, but was bootable from a USB drive. Other devices include the Kogan Agora Chromium Laptop by the Australian company Kogan and the Xi3 Modular Computer, introduced by the company of the same name. In late 2015, a team headed by Dylan Callahan released a beta Chromium OS port to the Raspberry Pi 2 single-board computer. In 2016, Flint Innovations released a Chromium OS port for the latest Raspberry Pi 3/B model named Flint OS for RPi. Subsequently, this project has been fully open-sourced at GitHub, with all the files and detailed instructions to re-create the build. Trademark dispute In June 2011, ISYS Technologies, based in Salt Lake City, sued Google in a Utah district court, claiming rights to the name "Chromium" and, by default, Chromebook and Chromebox. The suit sought to stop Google and its hardware and marketing partners from selling Chromebooks. The suit was later dismissed and, as part of an undisclosed settlement between Google and ISYS, ISYS abandoned its trademark efforts. See also Android (operating system) App Runtime for Chrome CoreOS Chromium (web browser) Google Fuchsia Firefox OS Google Chrome Chrome OS Webconverger an operating system based on Firefox Gentoo Linux References External links ARM operating systems Google Chrome Google software X86 operating systems Operating systems based on the Linux kernel Linux distributions without systemd 2009 software Linux distributions Gentoo Linux derivatives

Operating System (OS)

Windows Embedded Automotive Windows Embedded Automotive (formerly Microsoft Auto, Windows CE for Automotive, Windows Automotive, and Windows Mobile for Automotive) was an operating system subfamily of Windows Embedded based on Windows CE for use on computer systems in automobiles. The operating system is developed by Microsoft through the Microsoft Automotive Business Unit that formed in August 1995. The first automotive product built by Microsoft's Automotive Business Unit debuted on December 4, 1998 as the AutoPC, and also includes Ford Sync, Kia Uvo, and Blue&Me. Microsoft's Automotive Business Unit has built both the software platforms used for automotive devices as well as the devices themselves. The current focus is on the software platforms and includes two products, Microsoft Auto and Windows Automotive. History The Windows Embedded Automotive operating system was originally shipped with the AutoPC that was jointly developed by Microsoft and Clarion. The system was released in December 1998, and referred to the operating system itself as "Auto PC". Microsoft's Auto PC platform was based on Windows CE 2.0, and had been announced in January of that year. On October 16, 2000, Microsoft officially announced the next version of the platform. This version of the operating system was renamed to "Windows CE for Automotive" and had new applications preinstalled like the Microsoft Mobile Explorer. On October 21, 2002, Microsoft announced that the platform would be renamed to "Windows Automotive". The version added support for development using the .NET Compact Framework. Windows Automotive 4.2 reached General Availability on June 1, 2003 and Windows Automotive 5.0 reached GA on August 8, 2005. With the release of Ford Sync, Microsoft renamed the platform from "Windows Mobile for Automotive" to "Microsoft Auto". Microsoft again renamed the operating system as "Windows Embedded Automotive", and updated its version to 7 on October 19, 2010. This is the latest in MS Auto category, and is based on the Windows CE platform. Windows Embedded Automotive 7 reached GA on March 1, 2011. In December 2014, Ford announced that the company would be replacing Microsoft Auto with BlackBerry Limited's QNX. References External links Windows Embedded Automotive official website Windows CE

Operating System (OS)