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PCLinuxOS PCLinuxOS, often shortened to PCLOS, is an x86-64 Linux distribution, with KDE Plasma Desktop, MATE and XFCE as its default user interfaces. It is a primarily free software operating system for personal computers aimed at ease of use. It is considered a rolling release. History The precursor to PCLinuxOS was a set of RPM packages created to improve successive versions of Mandrake Linux (later Mandriva Linux). These packages were created by Bill Reynolds, a packager better known as Texstar. From 2000 to 2003, Texstar maintained his repository of RPM packages in parallel with the PCLinuxOnline site. In an interview, Reynolds said he started PCLinuxOS "to provide an outlet for [his] crazy desire to package source code without having to deal with egos, arrogance and politics." In October 2003, Texstar created a fork of Mandrake Linux 9.2. Working closely with The Live CD Project, Texstar has since developed that fork independently into a full-fledged distribution. The initial releases were successively numbered as "previews": p5, p7, p8 up to p81a, then p9, p91, p92, and p93. Although it retains a similar "look and feel" to Mandriva Linux, PCLinuxOS has diverged significantly. The code was officially forked from Mandrake 9.2 into an independent project in 2003. After three years of continuous development, the developers took advantage of further development in (the renamed) Mandriva late in 2006 for PCLinuxOS 2007. In the releases before 2007, it was normally necessary to perform a re-installation. PCLinuxOS 2007 For 2007, PCLinuxOS used a one-time source code snapshot from Mandriva to produce a new independent code base (no longer a fork of Mandriva). This implied a shift to a more modern code, which required a complete reinstallation to this version. The new version featured a new look and built-in 3D effects. A new logo was also designed for the new version, and was incorporated into the boot screen. A new login screen was designed, entitled "Dark". The final/official PCLinuxOS 2007 version was released on May 21, 2007. PCLinuxOS 2009 The last version of the 2009 Live CD, PCLinuxOS 2009.2, was released on June 30, 2009. Improvements included bug fixes, new backgrounds, sounds, and start-up screen, as well as quicker start-up times. It was the last PCLinuxOS live CD to ship with K Desktop Environment 3, and the last of the PCLinuxOS 2007 backward compatible series. Remasters of PCLinuxOS, featuring the Xfce (Phoenix), LXDE (PCLinuxOS-LXDE), and Gnome (PCLinuxOS-Gnome) desktops were also made available. PCLinuxOS 2010 The 2010 version of the Live CD was released on April 19, 2010. It includes the new KDE SC 4.4.2, a new graphical theme and a new version of the Linux Kernel (Kernel 2.6.32.11). It is also the first PCLinuxOS Live CD to include the ext4 file system support. This version required a complete reinstall of the operating system. While a version of PCLinuxOS that features the GNOME desktop environment was introduced in 2008, the 2010 version is the first one to not only offer the KDE Plasma and GNOME versions, but also versions with Xfce, LXDE, Enlightenment, and Openbox. PCLinuxOS 2010.1 Version 2010.1 was released on May 5, 2010. Changes made since last version: [The] Kernel has been updated to version 2.6.32.12-bfs. KDE Plasma Desktop has been upgraded to version 4.4.3. Support has been added for Realtek RTL8191SE/RTL8192SE WiFi cards and Microdia webcams. Vim console text editor and udftools has been added. Fixed CD-ROM ejection when using the Copy to RAM feature. Fixed KDE new widget download. Updated nVIDIA (195.36.24) and ATi fglrx (8.723) drivers. Updated all supporting applications and libraries from the software repository which include security updates and bug fixes. PCLinuxOS 2011.6 PCLinuxOS 2011.6 version was released on June 27, 2011. PCLinuxOS 2012 PCLinuxOS 2012.02 version was released on February 22, 2012. Later another maintenance release was made on August 22, 2012. Major changes compared to 2011 release are: Kernel has been updated to version 3.2 KDE version 4.8.2 nVIDIA and ATi fglrx driver support. PCLinuxOS 2013 64-bit PCLinuxOS 2013 64-bit first version was released on April 10, 2013. It featured: Kernel 3.2.18-pclos2.bfs for maximum desktop performance. Full KDE 4.10.1 Desktop. nVIDIA and ATi fglrx driver support. Multimedia playback support for many popular formats. Wireless support for many network devices. Printer support for many local and networked printer devices. Addlocale: allows you to translate PCLinuxOS into over 60 languages. LibreOffice preinstalled. LibreOffice Manager can install LibreOffice supporting over 100 languages. MyLiveCD allows you to take a snapshot of your installation and burn it to a LiveCD/DVD. PCLinuxOS-liveusb – allows you to install PCLinuxOS on a USB key disk. PCLinuxOS 2014.7 The new version was released on July 7, 2014. Features: kernel 3.15.4 for maximum desktop performance. Full KDE 4.12.3 Desktop. Nvidia and ATI fglrx driver support. Multimedia playback support for many popular formats. Wireless support for many network devices. Printer support for many local and networked printer devices. Addlocale allows you to convert PCLinuxOS into over 60 languages. LibreOffice Manager can install LibreOffice supporting over 100 languages. MyLiveCD allows you to take a snapshot of your installation and burn it to a LiveCD/DVD. PCLinuxOS-liveusb – allows you to install PCLinuxOS on a USB key disk Features PCLinuxOS places specific emphasis on desktop computing, concentrating its efforts for home or small business environments, hence paying less attention to other more "traditional" uses, like servers, although packages for most server tasks are available. PCLinuxOS is distributed as a Live CD, which can also be installed to a local hard disk drive or USB flash drive. Since version 2009.1, provides a USB installer to create a Live USB, where the user's configuration and personal data can be saved if desired. A live USB of older versions of PCLinuxOS can be created manually or with UNetbootin. The entire CD can be run from memory, assuming the system has sufficient RAM. PCLinuxOS uses APT-RPM, based on APT (Debian), a package management system (originally from the Debian distribution), together with Synaptic Package Manager, a GUI to APT, in order to add, remove or update packages. If there is enough memory on the machine, and an active network connection, the Live CD can update packages. PCLinuxOS is also designed to be easy to remaster after installation, creating one's own personalized Live CD, using the mylivecd tool. PCLinuxOS maintains its own software repository, available via the Advanced Packaging Tool (APT) and its Synaptic front-end, completely replacing Mandriva's urpmi. This means that an installation could be continuously updated to the latest versions of packages, hence sometimes forgoing the need to re-install the entire distribution upon each successive release. Other differences include its own menu arrangement, custom graphics, and icon sets. End of official support for 32bit version On May 10, 2016 main developer Texstar announced the end of support for 32bit versions of PCLinuxOS. As a result, 32bit ISOs of the distribution, official 32bit package updates and forum support ceased availability. While this doesn't prevent unofficial support, following the announcement only 64bit ISO images and package updates are available through the official webpage and channels. Other versions There are several community projects associated with PCLinuxOS. KDE Fullmonty (FM) edition (Discontinued) KDE FullMonty (Live & Install DVD) is a regular PCLinuxOS KDE installation, but is modified to include a special desktop layout and many additional applications and drives preinstalled. It is available as either a 32- or 64-bit edition. FM applies a new concept: activity-focused virtual desktop layout, which aims to address typical user-needs/tasks, make their life easy, and working on the computer straightforward and fun. It has 6 virtual desktops: The idea of the FM concept is to provide the best out-of-the-box experience in an intuitive, thematically organized desktop setup. FM is designed for Linux beginners and newcomers from other operating systems. The typical user is provided with a cream of the crop selection of activity-related applications available in PCLinuxOS. The most popular ones are easily accessible from the respective virtual desktop and many more applications can be accessed from the PCmenu. The variety of applications in FM serves several purposes: advertising those applications to users; stimulating the comparative usage of these applications in the forum, learning about and discussing specific application features, and finally helping deciding on and providing constructive feedback on finding the most popular application for a given task. FM should facilitate the entry into the Linux desktop experience and provide an intuitive and easy to use working environment. Trinity edition The Trinity edition of PCLinuxOS comes in 2 flavours, a mini-me that is a minimalist iso for those that want to customize their desktop with only the programs they want. The Other is Big Daddy, which includes all the codecs for multimedia, office tools and more out of the box programs. LXQt edition Xfce edition PCLOS community edition featuring XFCE desktop in a rolling release offers easy installation and setup, easy to update and works out of the box without systemd..a lot like MX-17 but non expiring. Bluetooth easiest working distro. MATE edition The newest edition of PCLinuxOS incorporates the MATE desktop environment, announced on the 3rd July 2013. PCLinuxOS Mate ISO is available in 64bit flavor only. This ISO is small enough to fit on a standard 700 mb CD or a small USB key. Features: Mate Desktop 1.6.x, Kernel 3.4.52, Pulse Audio enabled by default, Udisks2, Hal daemon turn off but still available as a service if needed. All of the Mate desktop applications plus Firefox, Thunderbird, Pidgin and Skype. Clementine and VLC multimedia players. PysolFC for recreation. Third-party distributions Because PCLinuxOS includes the mklivecd script, there have been several third-party distributions over the years based on PCLinuxOS, though they may only mention that connection if they follow strict guidelines. Release history Almost all major releases have been accompanied by new boot-up and login screens, along with some changes in icon sets, and login sounds. See also APT-RPM Mandriva Linux Rolling release References External links PCLinuxOS Magazine PCLinuxOS Zen mini archive PCLinuxOS on OpenSourceFeed Gallery KDE Live CD Live USB Mandriva Linux Operating system distributions bootable from read-only media RPM-based Linux distributions Linux distributions without systemd X86-64 Linux distributions Rolling Release Linux distributions Linux distributions

Operating System (OS)

List of BSD operating systems There are a number of Unix-like operating systems under active development, descended from the Berkeley Software Distribution (BSD) series of UNIX variants developed (originally by Bill Joy) at the University of California, Berkeley Electrical Engineering and Computer Science department. there were four major BSD operating systems, and an increasing number of other OSs derived from these, that add or remove certain features but generally remain compatible with their originating OS—and so are not really forks of them. This is a list of those that have been active since 2014, and their websites. FreeBSD-based FreeBSD is a free Unix-like operating system descended from AT&T UNIX via the Berkeley Software Distribution (BSD). FreeBSD currently has more than 200 active developers and thousands of contributors. Other notable derivatives include DragonFly BSD, which was forked from FreeBSD 4.8, and Apple Inc.'s macOS, with its Darwin base including a large amount of code derived from FreeBSD. DragonFly BSD-based NetBSD-based NetBSD is a freely redistributable, open source version of the Unix-derivative Berkeley Software Distribution (BSD) computer operating system. It was the second open source BSD descendant to be formally released, after 386BSD, and continues to be actively developed. Noted for its portability and quality of design and implementation, it is often used in embedded systems and as a starting point for the porting of other operating systems to new computer architectures. OpenBSD-based OpenBSD is a Unix-like computer operating system descended from Berkeley Software Distribution (BSD), a Unix derivative developed at the University of California, Berkeley. It was forked from NetBSD in 1995. OpenBSD includes a number of security features absent or optional in other operating systems and has a tradition of developers auditing the source code for software bugs and security problems. Historic BSD BSD was originally derived from Unix, using the complete source code for Sixth Edition Unix for the PDP-11 from Bell Labs as a starting point for the First Berkeley Software Distribution, or 1BSD. A series of updated versions for the PDP-11 followed (the 2.xBSD releases). A 32-bit version for the VAX platform was released as 3BSD, and the 4.xBSD series added many new features, including TCP/IP networking. For many years, the primary developer and project leader was Bill Joy, who was a graduate student at the time; funding for this project was provided by DARPA. DARPA was interested in obtaining a programming platform and programmer's interface which would provide a robust, general purpose, time-sharing computing platform which would not become obsolete every time computing hardware was or is replaced. Such an operating system would allow US Department of Defense software, especially for intricate, long-term finance and logistics operations, to be quickly ported to new hardware as it became available. As time went on, code was later ported both from and to Unix System III and still later Unix System V. Unix System V Revision 4 (SVR4), released circa 1992, contained much code which was ported from BSD version up to and including 4.3BSD. See also Comparison of BSD operating systems Commercial products based on FreeBSD References External links MiniOS - List of small OSes, with a section on BSD-based ones - MaheshaBSD in the BSD Magazine StarBSD List Lightweight Unix-like systems BSD operating systems BSD

Operating System (OS)

L4 microkernel family L4 is a family of second-generation microkernels, used to implement a variety of types of operating systems (OS), though mostly for Unix-like, Portable Operating System Interface (POSIX) compliant types. L4, like its predecessor microkernel L3, was created by German computer scientist Jochen Liedtke as a response to the poor performance of earlier microkernel-based OSes. Liedtke felt that a system designed from the start for high performance, rather than other goals, could produce a microkernel of practical use. His original implementation in hand-coded Intel i386-specific assembly language code in 1993 sparked intense interest in the computer industry. Since its introduction, L4 has been developed to be cross-platform and to improve security, isolation, and robustness. There have been various re-implementations of the original binary L4 kernel application binary interface (ABI) and its successors, including L4Ka::Pistachio (Karlsruhe Institute of Technology), L4/MIPS (University of New South Wales (UNSW)), Fiasco (Dresden University of Technology (TU Dresden)). For this reason, the name L4 has been generalized and no longer refers to only Liedtke's original implementation. It now applies to the whole microkernel family including the L4 kernel interface and its different versions. L4 is widely deployed. One variant, OKL4 from Open Kernel Labs, shipped in billions of mobile devices. Design paradigm Specifying the general idea of a microkernel, Liedtke states: A concept is tolerated inside the microkernel only if moving it outside the kernel, i.e., permitting competing implementations, would prevent the implementation of the system's required functionality. In this spirit, the L4 microkernel provides few basic mechanisms: address spaces (abstracting page tables and providing memory protection), threads and scheduling (abstracting execution and providing temporal protection), and inter-process communication (for controlled communication across isolation boundaries). An operating system based on a microkernel like L4 provides services as servers in user space that monolithic kernels like Linux or older generation microkernels include internally. For example, to implement a secure Unix-like system, servers must provide the rights management that Mach included inside the kernel. History The poor performance of first-generation microkernels, such as Mach, led a number of developers to re-examine the entire microkernel concept in the mid-1990s. The asynchronous in-kernel-buffering process communication concept used in Mach turned out to be one of the main reasons for its poor performance. This induced developers of Mach-based operating systems to move some time-critical components, like file systems or drivers, back inside the kernel. While this somewhat ameliorated the performance issues, it plainly violates the minimality concept of a true microkernel (and squanders their major advantages). Detailed analysis of the Mach bottleneck indicated that, among other things, its working set is too large: the IPC code expresses poor spatial locality; that is, it results in too many cache misses, of which most are in-kernel. This analysis gave rise to the principle that an efficient microkernel should be small enough that the majority of performance-critical code fits into the (first-level) cache (preferably a small fraction of said cache). L3 Jochen Liedtke set out to prove that a well designed thinner inter-process communication (IPC) layer, with careful attention to performance and machine-specific (in contrast to cross-platform software) design could yield large real-world performance improvements. Instead of Mach's complex IPC system, his L3 microkernel simply passed the message with no added overhead. Defining and implementing the required security policies were considered to be duties of the user space servers. The role of the kernel was only to provide the needed mechanism to enable the user-level servers to enforce the policies. L3, developed in 1988, proved itself a safe and robust operating system, used for many years for example by Technischer Überwachungsverein (Technical Inspection Association). L4 After some experience using L3, Liedtke came to the conclusion that several other Mach concepts were also misplaced. By simplifying the microkernel concepts even further he developed the first L4 kernel which was primarily designed for high performance. To extract every bit of performance, the whole kernel was written in assembly language, and its IPC was 20 times faster than Mach's. Such dramatic performance increases are a rare event in operating systems, and Liedtke's work triggered new L4 implementations and work on L4-based systems at a number of universities and research institutes, including IBM, where Liedtke started to work in 1996, TU Dresden and UNSW. At IBM's Thomas J. Watson Research Center Liedtke and his colleagues continued research on L4 and microkernel based systems in general, especially the Sawmill OS. L4Ka::Hazelnut In 1999, Liedtke took over the Systems Architecture Group at the University of Karlsruhe, where he continued the research into microkernel systems. As a proof of concept that a high performance microkernel could also be constructed in a higher level language, the group developed L4Ka::Hazelnut, a C++ version of the kernel that ran on IA-32- and ARM-based machines. The effort was a success, performance was still acceptable, and with its release, the pure assembly language versions of the kernels were effectively discontinued. L4/Fiasco In parallel to the development of L4Ka::Hazelnut, in 1998 the Operating Systems Group TUD:OS of the TU Dresden started to develop their own C++ implementation of the L4 kernel interface, named L4/Fiasco. In contrast to L4Ka::Hazelnut, which allows no concurrency in the kernel, and its successor L4Ka::Pistachio, which allows interrupts in the kernel only at specific preemption points, L4/Fiasco was fully preemptible (with the exception of extremely short atomic operations) to achieve a low interrupt latency. This was considered necessary because L4/Fiasco is used as the basis of DROPS, a hard real-time computing capable operating system, also developed at the TU Dresden. However, the complexities of a fully preemptible design prompted later versions of Fiasco to return to the traditional L4 approach of running the kernel with interrupts disabled, except for a limited number of preemption points. Cross-platform L4Ka::Pistachio Up until the release of L4Ka::Pistachio and newer versions of Fiasco, all L4 microkernels had been inherently tied close to the underlying CPU architecture. The next big shift in L4 development was the development of a cross-platform (platform-independent) application programming interface (API) that still retained the high performance characteristics despite its higher level of portability. Although the underlying concepts of the kernel were the same, the new API provided many significant changes relative to prior L4 versions, including better support for multi-processor systems, looser ties between threads and address spaces, and the introduction of user-level thread control blocks (UTCBs) and virtual registers. After releasing the new L4 API (version X.2 a.k.a. version 4) in early 2001, the System Architecture Group at the University of Karlsruhe implemented a new kernel, L4Ka::Pistachio, completely from scratch, now with focus on both high performance and portability. It was released under the two-clause BSD license. Newer Fiasco versions The L4/Fiasco microkernel has also been extensively improved over the years. It now supports several hardware platforms ranging from x86 through AMD64 to several ARM platforms. Notably, a version of Fiasco (Fiasco-UX) can run as a user-level application on Linux. L4/Fiasco implements several extensions to the L4v2 API. Exception IPC enables the kernel to send CPU exceptions to user-level handler applications. With the help of alien threads, it is possible to perform fine-grained control over system calls. X.2-style UTCBs have been added. Also, Fiasco contains mechanisms for controlling communication rights and kernel-level resource use. On Fiasco, a collection of basic user level services are developed (named L4Env) that among others are used to para-virtualise the current Linux version (4.19 ) (named L4Linux). University of New South Wales and NICTA Development also occurred at the University of New South Wales (UNSW), where developers implemented L4 on several 64-bit platforms. Their work resulted in L4/MIPS and L4/Alpha, resulting in Liedtke's original version being retrospectively named L4/x86. Like Liedtke's original kernels, the UNSW kernels (written in a mix of assembly and C) were unportable and each implemented from scratch. With the release of the highly portable L4Ka::Pistachio, the UNSW group abandoned their own kernels in favor of producing highly tuned ports of L4Ka::Pistachio, including the fastest-ever reported implementation of message passing (36 cycles on the Itanium architecture). The group has also demonstrated that device drivers can perform equally well at user-level as in-kernel, and developed Wombat, a highly portable version of Linux on L4 that runs on x86, ARM, and MIPS processors. On XScale processors, Wombat context-switching costs are up to 50 times lower than in native Linux. Later the UNSW group, at their new home at NICTA (formerly National ICT Australia, Ltd.), forked L4Ka::Pistachio into a new L4 version named NICTA::L4-embedded. As the name implies, it was for use in commercial embedded systems, and consequently the implementation trade-offs favored small memory size and reduced complexity. The API was modified to keep almost all system calls short enough that they need no preemption points to ensure high real-time responsiveness. Commercial deployment In November 2005, NICTA announced that Qualcomm was deploying NICTA's L4 version on their Mobile Station Modem chipsets. This led to the use of L4 in mobile phone handsets on sale from late 2006. In August 2006, ERTOS leader and UNSW professor Gernot Heiser spun out a company named Open Kernel Labs (OK Labs) to support commercial L4 users and further develop L4 for commercial use under the brand name OKL4, in close collaboration with NICTA. OKL4 Version 2.1, released in April 2008, was the first generally available version of L4 which featured capability-based security. OKL4 3.0, released in October 2008, was the last open-source version of OKL4. More recent versions are closed source and based on a rewrite to support a native hypervisor variant named the OKL4 Microvisor. OK Labs also distributed a paravirtualized Linux named OK:Linux, a descendant of Wombat, and paravirtualized versions of SymbianOS and Android. OK Labs also acquired the rights to seL4 from NICTA. OKL4 shipments exceeded 1.5 billion in early 2012, mostly on Qualcomm wireless modem chips. Other deployments include automotive infotainment systems. Apple A series processors beginning with the A7 contain a Secure Enclave coprocessor running an L4 operating system based on the L4-embedded kernel developed at NICTA in 2006. This implies that L4 is now shipping on all iOS devices, the total shipment of which is estimated at 310 million for the year 2015. High assurance: seL4 In 2006, the NICTA group commenced a from-scratch design of a third-generation microkernel, named seL4, with the aim of providing a basis for highly secure and reliable systems, suitable for satisfying security requirements such as those of Common Criteria and beyond. From the beginning, development aimed for formal verification of the kernel. To ease meeting the sometimes conflicting requirements of performance and verification, the team used a middle-out software process starting from an executable specification written in Haskell. seL4 uses capability-based security access control to enable formal reasoning about object accessibility. A formal proof of functional correctness was completed in 2009. The proof provides a guarantee that the kernel's implementation is correct against its specification, and implies that it is free of implementation bugs such as deadlocks, livelocks, buffer overflows, arithmetic exceptions or use of uninitialised variables. seL4 is claimed to be the first-ever general-purpose operating-system kernel that has been verified. seL4 takes a novel approach to kernel resource management, exporting the management of kernel resources to user level and subjects them to the same capability-based access control as user resources. This model, which was also adopted by Barrelfish, simplifies reasoning about isolation properties, and was an enabler for later proofs that seL4 enforces the core security properties of integrity and confidentiality. The NICTA team also proved correctness of the translation from the programming language C to executable machine code, taking the compiler out of the trusted computing base of seL4. This implies that the high-level security proofs hold for the kernel executable. seL4 is also the first published protected-mode OS kernel with a complete and sound worst-case execution time (WCET) analysis, a prerequisite for its use in hard real-time computing. On 29 July 2014, NICTA and General Dynamics C4 Systems announced that seL4, with end to end proofs, was now released under open-source licenses. The kernel source code and proofs are licensed under GNU General Public License version 2 (GPLv2), and most libraries and tools are under the BSD 2-clause. In April 2020, it was announced that the seL4 Foundation was created under the umbrella of the Linux Foundation to accelerate development and deployment of seL4. The researchers state that the cost of formal software verification is lower than the cost of engineering traditional "high-assurance" software despite providing much more reliable results. Specifically, the cost of one line of code during the development of seL4 was estimated at around , compared to for traditional high-assurance systems. Under the Defense Advanced Research Projects Agency (DARPA) High-Assurance Cyber Military Systems (HACMS) program, NICTA together with project partners Rockwell Collins, Galois Inc, the University of Minnesota and Boeing developed a high-assurance drone using seL4, along with other assurance tools and software, with planned technology transfer onto the optionally piloted autonomous Boeing AH-6 Unmanned Little Bird helicopter being developed by Boeing. Final demonstration of the HACMS technology took place in Sterling, VA in April 2017. DARPA also funded several Small Business Innovative Research (SBIR) contracts related to seL4 under a program started by Dr. John Launchbury. Small businesses receiving an seL4-related SBIR included: DornerWorks, Techshot, Wearable Inc, Real Time Innovations, and Critical Technologies. Other research and development Osker, an OS written in Haskell, targeted the L4 specification; although this project focused mainly on the use of a functional programming language for OS development, not on microkernel research. CodeZero is an L4 microkernel for embedded systems with a focus on virtualization and implementation of native OS services. There is a GPL-licensed version, and a version that was relicensed by B Labs Ltd., acquired by Nvidia, as closed source and forked in 2010. F9 microkernel, a BSD-licensed L4 implementation, is dedicated to ARM Cortex-M processors for deeply embedded devices with memory protection. The NOVA OS Virtualization Architecture is a research project with focus on constructing a secure and efficient virtualization environment with a small trusted computing base. NOVA consists of a microhypervisor, a user level hypervisor (virtual machine monitor), and an unprivileged componentised multi-server user environment running on it named NUL. NOVA runs on ARMv8-A and x86-based multi-core systems. WrmOS is a real-time operating system based on L4 microkernel. It has own implementations of kernel, standard libraries, and network stack, supporting ARM, SPARC, x86, and x86-64 architectures. There is the paravirtualized Linux kernel (w4linux) working on WrmOS. See also PikeOS References Further reading (on L4 kernel and compiler) Evolution of L4 design and implementation approaches External links , seL4 The L4 microkernel family, overview of L4 implementations, documentation, projects Official TUD:OS Wiki L4Ka: Implementations L4Ka::Pistachio and L4Ka::Hazelnut UNSW: Implementations for DEC Alpha and MIPS architecture : Commercial L4 version from Trustworthy Systems Group at CSIRO's Data61: Present home of the former NICTA group that developed seL4 Genode Operating System Framework: An offspring of the L4 community Capability systems Microkernels Assembly language software

Operating System (OS)

The Unix System The Unix System () is a book by Stephen R. Bourne. Published in 1982, it was the first widely available general introduction to the Unix operating system. It included some historical material on Unix, as well as material on using the system, editing, the software tools concept, C programming using the Unix API, data management with the shell and awk, and typesetting with troff. 1982 non-fiction books Addison-Wesley books Computer books Unix books

Operating System (OS)

The Linux Schools Project The Linux Schools Project (formerly Karoshi, which can be translated literally as "death from overwork" in Japanese) is an operating system designed for schools. It is a Linux distribution based on Ubuntu (operating system). The project maintains two custom distributions, with one designed for use on servers and the other for use with the server version on client machines. The server distribution is the official Karoshi, while the client is known as Karoshi Client. TLSP uses prepackaged GUI scripts in order to simplify the install and configuration process for inexperienced users. History TLSP was originally developed using Red Hat, early in the 2000s with the aim of making Linux adoption easier for schools in the UK. Linux, at the time, was considered difficult to use in educational environments where computing expertise mainly came from teachers who were not dedicated IT staff. With version 5.1.x, TLSP moved to the PCLinuxOS platform - but has since adopted Ubuntu in its place. The current production version of TLSP is 12.1. Features TLSP is downloadable from their homepage. The installation steps require an initial install of Ubuntu, which the Live CD prompts to initiate. Following the machine reboot after installation of Ubuntu, the install of the TLSP system is initiated automatically. Educational TLSP is primarily aimed at educational environments, but is also suitable for use in a Small to Medium Enterprise (SME) business environment. The included systems are suitable for use as file and print, email, web and e-learning servers. By leveraging these technologies, it is possible to administer a complete network using the integrated web tools and by using some form of remote desktop technology. Server Distribution Primary Domain Controller Capability The TLSP system is a scalable single or multi server system, comprising many features. Chief among these are the ability to act as a Primary Domain Controller in a Windows network. TLSP uses built in Samba and LDAP servers to store user, group and computer information, and emulates a Microsoft Windows NT 4.0 server system using these technologies, providing computer and user authentication, along with file and print services on the local network. TLSP creates a standard Windows domain for the local network, and names it linuxgrid. KiXtart TLSP uses KiXtart scripts to set up Windows XP clients on the domain, providing mandatory profiles to most users on the system. Roaming profiles can be used, but are not recommended, due to the heavy network overhead involved. Using mandatory profiles and folder redirection to mapped file shares on the server, allows every user to store his own files in his "My Documents" folder. Servers TLSP includes the Moodle e-learning package, and several website content management systems, including Joomla! and Website Baker. eGroupWare and SquirrelMail are built into the system, allowing for full calendar and email facilities. These can be installed on a standalone machine in the DMZ section, thus providing increased security on systems that are directly exposed to the internet. WPKG Particularly interesting is the inclusion of WPKG, which enables the remote installation of software on Windows clients. By using a machine profile stored on the server, it is possible to install software packages, hotfixes, and security updates in the background. It is also very helpful in terms of creating machine profiles, allowing a 'blank' Windows XP machine to be updated automatically to a particular WPKG profile, once the machine is added to the domain. This type of technology can be compared to the group policy mechanism in Windows Server 2003, particularly from a machine administration perspective. It is by no means a replacement for group policy, but is a step in the right direction. Client Distribution The first version of Karoshi Client was based on PCLinuxOS. Further upgrades to the system as a whole led to the client using a modified version of Ubuntu 10.04 LTS with a GUI similar to the Microsoft Windows interface. The interface was designed to be fast, as to run well on older hardware. In June 2012 work was started on Karoshi Client version 2, which would have an interface closer to Gnome 2 than Windows. Development of the client release was given to Robin McCorkell - a student of Dover Grammar School for Boys. On 21 July 2012 Karoshi Client 2 was uploaded to Sourceforge.net. Technical Karoshi Client contains many applications which were deemed necessary for school work. Media production software (including music production, image manipulation, and video editing software) are included, along with programming tools and visualization software. Many IDEs are installed by default, mainly set for use with Java, but also supporting C/C++ programming or other languages. The C++ compiler and standard libraries are installed by default, along with the Boost libraries, ncurses and Mesa libraries for OpenGL programming. The Java Development Kit is installed, and integrated with the installed IDEs. Xfce is used as the desktop manager, with a customized theme and panel layout. The developer ported the Clearlooks GTK2 theme to GTK3 so that Gnome 3 applications like gEdit would display correctly. The panel layout is similar to the Gnome 2 environment. Compositing effects have been enabled by default for the environment. The interface settings are locked down in the Xfce configuration files due to the need for suitability in a school environment, where children may try and play with the settings. The KDE greeter for LightDM is used for the log in screen, due to problems with KDM and Ubiquity. This version of Karoshi Client is more integrated with the server distribution than the previous client releases, with most of the custom configuration files pulled down from a primary domain controller on boot up. A server patch that added in the correct files for the client was released on 23 July 2012. Limitations It used to be difficult to integrate TLSP into an existing Windows network, without changing the address space to the standard one that is used by the TLSP system. This was only a limitation in early versions and no longer applies. Future Plans Kerberos support is planned for the Karoshi server and client system, providing single sign on to all services provided by the Karoshi distribution. This will be unfeasible until Samba 4 is released due to the complexities surrounding integration of user resolution and file access across multiple operating systems, such as those that do not support the Active Directory protocols. Some integration has occurred already with a working client system that authenticates using Kerberos, then authenticates successfully with Moodle, Samba and Squid using Kerberos credentials. References External links WPKG Homepage Debian-based distributions Linux distributions

Operating System (OS)

ISIS (operating system) ISIS, short for Intel System Implementation Supervisor, is an operating system for early Intel microprocessors like the 8080. It was originally developed by Ken Burgett and Jim Stein under the management of Steve Hanna and Terry Opdendyk for the Intel Microprocessor Development System with two 8" floppy drives, starting in 1975, and later adopted as ISIS-II as the operating system for the PL/M compiler, assembler, link editor, and In-Circuit Emulator (developed by Steve Morse). The ISIS operating system was developed on an early prototype of the MDS 800 computer, the same type of hardware that Gary Kildall used to develop CP/M. Overview Communication with the user is terminal-like. Its user interface is somewhat CP/M-like, even from the program interface point of view. For file opening, the program sends the name of file and gets back a handle. Each device has a name, which is entered between a pair of colons (:F0: and :F1: are floppies, :LP: is printer, etc.). Each diskette has one directory and no subdirectories. ISIS-II has been distributed as part of the Intel Microprocessor Development System and includes standard operating system commands (COPY, DELETE, DIR, RENAME, FORMAT) and debugging software (assembler, linker and debugger for external debugging in the developed device). There are two editors, one of which, AEDIT, contains editing macros support. File editing is provided directly on diskette (a .BAK file is always created). The other editor is CREDIT. ISIS-II needed at least 32 kilobytes of RAM, the 8080/8085 CPU maximum address space was 64 kilobytes. In the MDS-800 and Series-II, the Monitor occupied F800h to FFFFh. Floppy disk format was 8-inch single-sided, 250 KB single-sided, single-density FM, or 500 KB single-sided, double-density MMFM. ISIS-PDS was also software and media incompatible and unique, it came on 720 KB DSDD 5¼-inch floppies with the Intel personal development system (iPDS-100). The ISIS-IV operating system was another incompatible (even with other Intel development systems) that ran on the iMDX-430 Series-IV Network Development System-II. Intel ASM80, PLM-80, BASIC-80, COBOL-80, FORTRAN-80 were all available for ISIS-II. ASM86, ASM48, ASM51 were available as well. Commands The following list of commands are supported by the ISIS-II console. IDISK FORMAT FIXMAP DEBUG SUBMIT DIR COPY HDCOPY DELETE RENAME ATTRIB BINOBJ HEXOBJ OBJHEX EDIT LIB LINK LOCATE See also CONV86 CP/M RMX (operating system) or iRMX References External links ISIS-MDS Obsolete ISIS SW, MDS HW Retrieved 2016-11-24 Intel MDS 80 - Microcomputer Development System Joe's Intel MDS web page ISIS II Users Guide Intel ISIS Command-Video Reverse engineered source Additional reverse engineered source ISX - An ISIS-II emulator Intel software Microcomputer software Disk operating systems Floppy disk-based operating systems

Operating System (OS)

CherryOS CherryOS was a PowerPC G4 processor emulator for x86 Microsoft Windows platforms, which allowed various Apple Inc. programs to be operated on Windows XP. Announced and made available for pre-orders on October 12, 2004, it was developed by Maui X-Stream (MXS), a startup company based in Lahaina, Hawaii and a subsidiary of Paradise Television. The program encountered a number of launch difficulties its first year, including a poorly-reviewed soft launch in October 2004, wherein Wired Magazine argued that CherryOS used code grafted directly from PearPC, an older open-source emulator. Lead developer Arben Kryeziu subsequently stated that PearPC had provided the inspiration for CherryOS, but "not the work, not the architecture. With their architecture I'd never get the speed." After further development, CherryOS 1.0 was released in its final form on March 8, 2005, with support for CD, DVD, USB, FireWire, and Ethernet. It was described as automatically detecting "hardware and network connections" and allowing "for the use of virtually any OS X-ready application," including Safari and Mail. Estimated to be compatible with approximately 70 percent of PCs, MXS again fielded accusations that CherryOS 1.0 incorporated code from PearPC. MXS argued CherryOS was "absolutely not" a knockoff," and that though "certain generic code strings and screen verbiage used in Pear PC are also used in CherryOS... they are not proprietary to the Pear PC product." Shortly afterwards the creators of PearPC were reported to be "contemplating" litigation against Maui X-Stream, and on April 6, 2005, CherryOS was announced to be on hold. A day later, CherryOS announced that "due to overwhelming demand, Cherry open source project launches May 1, 2005." History Background and development On October 12, 2004, the emulator CherryOS was announced by Maui X-Stream (MXS), a startup company based in Lahaina, Hawaii and a subsidiary of Paradise Television. At the time MXS was best known for developing software for video streaming, particularly their VX3 encoder. As a new emulator intended to allow Mac OS X to be utilized on x86 computer architecture, CherryOS was advertised as working on Windows 98, Windows 2000 or Windows XP, with features such as allowing files to be dragged from PC to Mac, the creation of multiple profiles, and support for networking and sound. With development led by MXS employee and software developer Arben Kryeziu, CherryOS was made available for pre-order on the MXS website. Some articles hailed CherryOS as a new potential competitor for programs such as MacWindows, while the Irish Times would later write that certain groups of consumers "were suspicious as to how a little-known Hawaii-based outfit... could suddenly do something that had evaded much larger firms." In explaining the suspicion, Ars Technica later noted that emulators by small developers like PearPC had reputations for working extremely slowly, meaning CherryOS's claim of operating 80 percent of the host PC's speed would have been "a major breakthrough" in the industry. When asked by the Star Bulletin, at this point Kryeziu denied any possibility that CherryOS would contain code from a rival program like Apple, MacWindows, Emulators.com, or PearPC, stating that "our lawyers have looked at this and say we're in the clear. We wrote this from scratch and we're clean as a whistle." According to the Star Bulletin, suspicions that CherryOS might be a hoax "were fanned" by glitches on the CherryOS home website, and three days after the site opened for pre-sales it crashed after taking 300,000 daily hits. MXS president Jim Kartes crediting the crash on both unexpected high traffic and Mac "purists" who had hacked and destroyed the servers, and though MXS continued to accept non-digital pre-orders, by October 19 the CherryOS website was offline entirely as MXS switched to a new web host. Pre-release version Initially the company did not offer a trial version of CherryOS, citing concerns the code might be pirated. However, "as a direct result of the overwhelming response to our October 12 announcement," as of October 15 the company was readying a free beta version with a projected release date of November 25, 2004. On October 18, Kryeziu stated that a free public demo would be released within a week, and CherryOS was first registered to be trademarked in the United States on October 19, 2004. On October 19, however, Kryeziu withheld a timetable for the CherryOS release, stating the company had been pre-emptive in releasing the earlier "soft launch" version, and that CherryOS still had too many software bugs to predict a release date. Wired News reviewed a pre-release version around this time, reporting on October 22 that an expert had found distinguishing "watermarks" from PearPC's source code in CherryOS. Moreover, the pre-release version was reviewed to run at the same slow speed as PearPC, though Wired noted "they've actually done some work on it. They've written a whole graphical interface that makes [PearPC] easier to use." In response to the article, MXS stated that the edition tested by Wired had been a "very bad...premature version" that "is not CherryOS," and that one of the CherryOS programmers had since been fired for directly grafting elements of PearPC code into the release. A competing emulator, PearPC been released the year before under the GNU General Public License, which allows commercial products to use the software for profit under "certain conditions, such as acknowledging previous work." Kryeziu stated PearPC had provided the inspiration for CherryOS, but "not the work, not the architecture. With their architecture I'd never get the speed I got." He argued that some similarities between CherryOS and PearPC were a result of "the fact that they were designed to perform similar functions," and that "there are some functionalities that can only be done a certain way, and names are going to be similar or identical." Wired senior editor Leander Kahney posited that if the final CherryOS release did contain PearPC code, PearPC would be unlikely to sue Maui X-Stream for "a cut of any profits since open-source codes are protected more by an honor system than any legal basis." By October 22, Kryeziu stated to Wired that he'd been contacted by Apple Computer for an undisclosed reason that "wasn't bad." CherryOS 1.0 release After a delay, CherryOS 1.0 was released in its final form on March 8, 2005. Maui-X Stream initially offered a free copy for evaluation on its website, with 14 boot allowances and five free days per copy. According to MXS president Jim Kartes, within the first few days the free version was downloaded 100,000 times. Stated Kartes to the Mac Observer on March 8, 2005, "there has been a lot of misinformation about this product... I think we have proven those skeptics wrong." Initial reports of certain computers encountering slow speeds and glitches were explained by MXS as "expected," as "it's got bugs. That is why we're offering a free trial download. If it doesn't work, they shouldn't buy it.... we will use the testing of consumers to improve its stability and performance." Kartes extrapolated that after development, somewhere between "60% and 70% of all PC owners" would be able to use the CherryOS product. MXS announced plans to market CherryOS throughout the summer of 2005, but withheld specifics on when it would be released for sale. BetaNews.com reviewed CherryOS upon its public release, arguing that there were again similarities between CherryOS and PearPC, including specific non-generic lines of code. Maui X-Stream president Jim Kartes denied that CherryOS had grafted in PearPC code, and on March 24, 2005, a spokesperson for CherryOS stated to the Irish Times that CherryOS 1.0 was "absolutely not" a knockoff of Pear PC, as "there are considerable differences between the two products: Both products emulate the Apple operating system but the similarity ends there." The spokesperson further explained that "certain generic code strings and screen verbiage used in Pear PC are also used in CherryOS. They are not proprietary to the Pear PC product. For example, Pear tops out at G3 emulation and CherryOS is the only stable G4 emulator on the market today. CherryOS uses multithreading architecture for speed and ease of use. Pear employs a step-by-step approach; CherryOS features a shared-drive emulator, a drag-and-drop option allows you to connect the Windows drive to a Mac environment and CherryOS is the only emulator to support sound." Kartes further stated that although PearPC introduced their code before CherryOS, that "doesn't give them a claim on certain technical aspects of our product." On March 30, 2005, Ars Technica reported that the creators of PearPC were "contemplating" litigation against Maui X-Stream. On April 6, 2005, Cherry OS was announced by its developers to be on hold "until further notice." A day later, CherryOS announced on its website that it would no longer be a commercial product, and that "due to overwhelming demand, Cherry open source project launches May 1, 2005." The trademark for CherryOS was filed as abandoned as of June 21, 2006. Technical features Overview CherryOS was a PowerPC G4 processor emulator for x86 Microsoft Windows platforms. Originally written to work with Windows 98, Windows 2000 or Windows XP, among other features Cherry OS purported to allow files to be dragged from PC to Mac, the creation of multiple profiles, support skins, and support for networking and sound. In October 2004, the program's developer announced CherryOS as having "full network capabilities" and "complete access to the host computer's hardware resources - hard drive, CPU, RAM, FireWire, USB, PCI, PCMCIA bus, Ethernet networking and modem." By October 21, 2004, the program was reported to be a 7 MB download with Velocity Engine included. At the time, MMX stated they were developing 3D acceleration for CherryOS. The program was publicly released on March 8, 2005, with support for CD, DVD, USB, FireWire, and Ethernet. It was described as automatically detecting "hardware and network connections" and allowing "for the use of virtually any OS X-ready application," including Safari and Mail by Apple. Estimated to be compatible with approximately 70 percent of PCs, the CherryOS system required a Pentium 4 1.6 gigahertz (GHz) CPU or equivalent hardware and Windows XP, as well as 512 megabytes of memory and 3 gigabytes of hard drive space. After the initial March 8 release, speed of CherryOS 1.0 was reported to be variable. Karol McGuire of MXS stated that speed was depended on computer processor, as "a processor that has inadequate space on the hard drive or that runs at less than optimum operating speeds will not allow CherryOS to perform as designed." Following the public launch, the company announced that Kryeziu would be overseeing development on "sound support and network bridging, as well as improving speed." Kryeziu explained "we think we'll have the first two issues solved fairly soon. It's the type of product that will be continually updated as we go along. We think we can make it faster than it is right now, but this will take time." Apple TOS For its year in development, there was some question in the press as to the legality of CherryOS in relation to Apple's "Use and Restrictions" agreement, which only allows Apple programs to be used on a singular "Apple-labeled computer" at one time. The publication Ars Technica notes, however, that "a PPC emulator [like CherryOS or PearPC] isn't just for violating ToS agreements and bringing down the wrath of Apple Legal. It has legitimate uses too... you could use an emulator to run a PPC version of Linux on x86 hardware, and you could even use a P2P network to get that distribution of Linux, justifying two technologies with one rationalization." Despite this fact, the Irish Times pointed out that CherryOS was marketed exclusively to run Mac OSX, which it argued was "clear" violation of the OS X license agreement. Versions See also List of computer simulation software List of emulators Comparison of platform virtualization software References External links "CherryOS goes open source" - article by Jim Dalrymple for MacWorld (April 2005) Windows emulation software Virtualization software Vaporware PowerPC emulators Discontinued software Free emulation software

Operating System (OS)

Open-source hardware Open-source hardware (OSH) consists of physical artifacts of technology designed and offered by the open-design movement. Both free and open-source software (FOSS) and open-source hardware are created by this open-source culture movement and apply a like concept to a variety of components. It is sometimes, thus, referred to as FOSH (free and open-source hardware). The term usually means that information about the hardware is easily discerned so that others can make it – coupling it closely to the maker movement. Hardware design (i.e. mechanical drawings, schematics, bills of material, PCB layout data, HDL source code and integrated circuit layout data), in addition to the software that drives the hardware, are all released under free/libre terms. The original sharer gains feedback and potentially improvements on the design from the FOSH community. There is now significant evidence that such sharing can drive a high return on investment for the scientific community. It is not enough to merely use an open-source license; an open source product or project will follow open source principles, such as modular design and community collaboration. Since the rise of reconfigurable programmable logic devices, sharing of logic designs has been a form of open-source hardware. Instead of the schematics, hardware description language (HDL) code is shared. HDL descriptions are commonly used to set up system-on-a-chip systems either in field-programmable gate arrays (FPGA) or directly in application-specific integrated circuit (ASIC) designs. HDL modules, when distributed, are called semiconductor intellectual property cores, also known as IP cores. Open-source hardware also helps alleviate the issue of proprietary device drivers for the free and open-source software community, however, it is not a pre-requisite for it, and should not be confused with the concept of open documentation for proprietary hardware, which is already sufficient for writing FLOSS device drivers and complete operating systems. The difference between the two concepts is that OSH includes both the instructions on how to replicate the hardware itself as well as the information on communication protocols that the software (usually in the form of device drivers) must use in order to communicate with the hardware (often called register documentation, or open documentation for hardware), whereas open-source-friendly proprietary hardware would only include the latter without including the former. History The first hardware-focused "open source" activities were started around 1997 by Bruce Perens, creator of the Open Source Definition, co-founder of the Open Source Initiative, and a ham radio operator. He launched the Open Hardware Certification Program, which had the goal of allowing hardware manufacturers to self-certify their products as open. Shortly after the launch of the Open Hardware Certification Program, David Freeman announced the Open Hardware Specification Project (OHSpec), another attempt at licensing hardware components whose interfaces are available publicly and of creating an entirely new computing platform as an alternative to proprietary computing systems. In early 1999, Sepehr Kiani, Ryan Vallance and Samir Nayfeh joined efforts to apply the open-source philosophy to machine design applications. Together they established the Open Design Foundation (ODF) as a non-profit corporation and set out to develop an Open Design Definition. However, most of these activities faded out after a few years. A "Free Hardware" organization, known as FreeIO, was started in the late 1990s by Diehl Martin, who also launched a FreeIO website in early 2000. In the early to mid 2000s, FreeIO was a focus of free/open hardware designs released under the GNU General Public License. The FreeIO project advocated the concept of Free Hardware and proposed four freedoms that such hardware provided to users, based on the similar freedoms provided by free software licenses. The designs gained some notoriety due to Martin's naming scheme in which each free hardware project was given the name of a breakfast food such as Donut, Flapjack, Toast, etc. Martin's projects attracted a variety of hardware and software developers as well as other volunteers. Development of new open hardware designs at FreeIO ended in 2007 when Martin died of pancreatic cancer but the existing designs remain available from the organization's website. By the mid 2000s open-source hardware again became a hub of activity due to the emergence of several major open-source hardware projects and companies, such as OpenCores, RepRap (3D printing), Arduino, Adafruit and SparkFun. In 2007, Perens reactivated the openhardware.org website. Following the Open Graphics Project, an effort to design, implement, and manufacture a free and open 3D graphics chip set and reference graphics card, Timothy Miller suggested the creation of an organization to safeguard the interests of the Open Graphics Project community. Thus, Patrick McNamara founded the Open Hardware Foundation (OHF) in 2007. The Tucson Amateur Packet Radio Corporation (TAPR), founded in 1982 as a non-profit organization of amateur radio operators with the goals of supporting R&D efforts in the area of amateur digital communications, created in 2007 the first open hardware license, the TAPR Open Hardware License. The OSI president Eric S. Raymond expressed some concerns about certain aspects of the OHL and decided to not review the license. Around 2010 in context of the Freedom Defined project, the Open Hardware Definition was created as collaborative work of many and is accepted as of 2016 by dozens of organizations and companies. In July 2011, CERN (European Organization for Nuclear Research) released an open-source hardware license, CERN OHL. Javier Serrano, an engineer at CERN's Beams Department and the founder of the Open Hardware Repository, explained: "By sharing designs openly, CERN expects to improve the quality of designs through peer review and to guarantee their users – including commercial companies – the freedom to study, modify and manufacture them, leading to better hardware and less duplication of efforts". While initially drafted to address CERN-specific concerns, such as tracing the impact of the organization's research, in its current form it can be used by anyone developing open-source hardware. Following the 2011 Open Hardware Summit, and after heated debates on licenses and what constitutes open-source hardware, Bruce Perens abandoned the OSHW Definition and the concerted efforts of those involved with it. Openhardware.org, led by Bruce Perens, promotes and identifies practices that meet all the combined requirements of the Open Source Hardware Definition, the Open Source Definition, and the Four Freedoms of the Free Software Foundation Since 2014 openhardware.org is not online and seems to have ceased activity. The Open Source Hardware Association (OSHWA) at oshwa.org acts as hub of open-source hardware activity of all genres, while cooperating with other entities such as TAPR, CERN, and OSI. The OSHWA was established as an organization in June 2012 in Delaware and filed for tax exemption status in July 2013. After some debates about trademark interferences with the OSI, in 2012 the OSHWA and the OSI signed a co-existence agreement. FSF's Replicant project suggested in 2016 an alternative "free hardware" definition, derived from the FSF's four freedoms. Forms of open-source hardware The term hardware in open-source hardware has been historically used in opposition to the term software of open-source software. That is, to refer to the electronic hardware on which the software runs (see previous section). However, as more and more non-electronic hardware products are made open source (for example WikiHouse, OpenBeam or Hovalin), this term tends to be used back in its broader sense of "physical product". The field of open-source hardware has been shown to go beyond electronic hardware and to cover a larger range of product categories such as machine tools, vehicles and medical equipment. In that sense, hardware refers to any form of tangible product, be it electronic hardware, mechanical hardware, textile or even construction hardware. The Open Source Hardware (OSHW) Definition 1.0 defines hardware as "tangible artifacts — machines, devices, or other physical things". Computers Due to a mixture of privacy, security, and environmental concerns, a number of projects have started that aim to deliver a variety of open-source computing devices. Examples include the EOMA68 (SBC in a PCMCIA form-factor, intended to be plugged into a laptop or desktop chassis), Novena (bare motherboard with optional laptop chassis), and GnuBee (series of Network Attached Storage devices). Several retrocomputing hobby groups have created numerous recreations or adaptations of the early home computers of the 1970s and 80s, some of which include improved functionality and more modern components (such as surface-mount ICs and SD card readers). Some hobbyists have also developed add-on cards (such as drive controllers, memory expansion, and sound cards) to improve the functionality of older computers. Miniaturised recreations of vintage computers have also been created. Electronics Electronics is one of the most popular types of open-source hardware. There are many companies that provide large varieties of open-source electronics such as Sparkfun, Adafruit and Seeed. In addition, there are NPOs and companies that provide a specific open-source electronic component such as the Arduino electronics prototyping platform. There are many examples of specialty open-source electronics such as low-cost voltage and current GMAW open-source 3-D printer monitor and a robotics-assisted mass spectrometry assay platform. Open-source electronics finds various uses, including automation of chemical procedures. Mecha(tro)nics A large range of open-source mechatronic products have been developed, including mechanical components, machine tools, vehicles, musical instruments, and medical equipment. Examples of open-source machine tools include 3D printers such as RepRap, Prusa, and Ultimaker, 3D printer filament extruders such as polystruder XR3 and as well as the laser cutter Lasersaur. Open-source vehicles have also been developed including bicycles like XYZ Space Frame Vehicles and cars such as the Tabby OSVehicle. Examples of open source medical equipment include open-source ventilators, the echostethoscope echOpen, and a wide range of prosthetic hands listed in the review study by Ten Kate et.al. (e.g. OpenBionics’ Prosthetic Hands). Other Examples of open-source hardware products can also be found to a lesser extent in construction (Wikihouse), textile (Kit Zéro Kilomètres), and firearms (3D printed firearm, Defense Distributed). Licenses Rather than creating a new license, some open-source hardware projects use existing, free and open-source software licenses. These licenses may not accord well with patent law. Later, several new licenses were proposed, designed to address issues specific to hardware design. In these licenses, many of the fundamental principles expressed in open-source software (OSS) licenses have been "ported" to their counterpart hardware projects. New hardware licenses are often explained as the "hardware equivalent" of a well-known OSS license, such as the GPL, LGPL, or BSD license. Despite superficial similarities to software licenses, most hardware licenses are fundamentally different: by nature, they typically rely more heavily on patent law than on copyright law, as many hardware designs are not copyrightable. Whereas a copyright license may control the distribution of the source code or design documents, a patent license may control the use and manufacturing of the physical device built from the design documents. This distinction is explicitly mentioned in the preamble of the TAPR Open Hardware License: Noteworthy licenses include: The TAPR Open Hardware License: drafted by attorney John Ackermann, reviewed by OSS community leaders Bruce Perens and Eric S. Raymond, and discussed by hundreds of volunteers in an open community discussion Balloon Open Hardware License: used by all projects in the Balloon Project Although originally a software license, OpenCores encourages the LGPL Hardware Design Public License: written by Graham Seaman, admin of Opencollector.org In March 2011 CERN released the CERN Open Hardware License (OHL) intended for use with the Open Hardware Repository and other projects. The Solderpad License is a version of the Apache License version 2.0, amended by lawyer Andrew Katz to render it more appropriate for hardware use. The Open Source Hardware Association recommends seven licenses which follow their open-source hardware definition. From the general copyleft licenses the GNU General Public License (GPL) and Creative Commons Attribution-ShareAlike license, from the hardware-specific copyleft licenses the CERN Open Hardware License (OHL) and TAPR Open Hardware License (OHL) and from the permissive licenses the FreeBSD license, the MIT license, and the Creative Commons Attribution license. Openhardware.org recommended in 2012 the TAPR Open Hardware License, Creative Commons BY-SA 3.0 and GPL 3.0 license. Organizations tend to rally around a shared license. For example, OpenCores prefers the LGPL or a Modified BSD License, FreeCores insists on the GPL, Open Hardware Foundation promotes "copyleft or other permissive licenses", the Open Graphics Project uses a variety of licenses, including the MIT license, GPL, and a proprietary license, and the Balloon Project wrote their own license. Development The adjective "open-source" not only refers to a specific set of freedoms applying to a product, but also generally presupposes that the product is the object or the result of a "process that relies on the contributions of geographically dispersed developers via the Internet." In practice however, in both fields of open-source hardware and open-source software, products may either be the result of a development process performed by a closed team in a private setting or by a community in a public environment, the first case being more frequent than the second which is more challenging. Establishing a community-based product development process faces several challenges such as: to find appropriate product data management tools, document not only the product but also the development process itself, accepting losing ubiquitous control over the project, ensure continuity in a context of fickle participation of voluntary project members, among others. One of the major differences between developing open-source software and developing open-source hardware is that hardware results in tangible outputs, which cost money to prototype and manufacture. As a result, the phrase "free as in speech, not as in beer", more formally known as Gratis versus Libre, distinguishes between the idea of zero cost and the freedom to use and modify information. While open-source hardware faces challenges in minimizing cost and reducing financial risks for individual project developers, some community members have proposed models to address these needs Given this, there are initiatives to develop sustainable community funding mechanisms, such as the Open Source Hardware Central Bank. Extensive discussion has taken place on ways to make open-source hardware as accessible as open-source software. Providing clear and detailed product documentation is an essential factor facilitating product replication and collaboration in hardware development projects. Practical guides have been developed to help practitioners to do so. Another option is to design products so they are easy to replicate, as exemplified in the concept of open-source appropriate technology. The process of developing open-source hardware in a community-based setting is alternatively called open design, open source development or open source product development. All these terms are examples of the open-source model applicable for the development of any product, including software, hardware, cultural and educational. See here for a delineation of these terms. A major contributor to the production of open-source hardware product designs is the scientific community. There has been considerable work to produce open-source hardware for scientific hardware using a combination of open-source electronics and 3-D printing. Other sources of open-source hardware production are vendors of chips and other electronic components sponsoring contests with the provision that the participants and winners must share their designs. Circuit Cellar magazine organizes some of these contests. Open-source labs A guide has been published (Open-Source Lab (book) by Joshua Pearce) on using open-source electronics and 3D printing to make open-source labs. Today, scientists are creating many such labs. Examples include: Boston Open Source Science Laboratory, Somerville, Massachusetts BYU Open Source Lab, Brigham Young University Michigan Tech National Tsing Hua University OSU Open Source Lab, Oregon State University Open Source Research Lab, University of Texas at El Paso Business models Open hardware companies are experimenting with business models. For example, littleBits implements open-source business models by making available the circuit designs in each littleBits module, in accordance with the CERN Open Hardware License Version 1.2. Another example is Arduino, which registered its name as a trademark; others may manufacture products from Arduino designs but cannot call the products Arduino products. There are many applicable business models for implementing some open-source hardware even in traditional firms. For example, to accelerate development and technical innovation, the photovoltaic industry has experimented with partnerships, franchises, secondary supplier and completely open-source models. Recently, many open-source hardware projects were funded via crowdfunding on Indiegogo or Kickstarter. Especially popular is Crowd Supply for crowdfunding open hardware projects. Reception and impact Richard Stallman, the founder of the free software movement, was in 1999 skeptical on the idea and relevance of free hardware (his terminology for what is now known as open-source hardware). In a 2015 article in Wired Magazine, he modified this attitude; he acknowledged the importance of free hardware, he still saw no ethical parallel with free software. Also, Stallman prefers the term free hardware design over open source hardware, a request which is consistent with his earlier rejection of the term open source software (see also Alternative terms for free software). Other authors, such as Professor Joshua Pearce have argued there is an ethical imperative for open-source hardware – specifically with respect to open-source appropriate technology for sustainable development. In 2014, he also wrote the book Open-Source Lab: How to Build Your Own Hardware and Reduce Research Costs, which details the development of free and open-source hardware primarily for scientists and university faculty. Pearce in partnership with Elsevier introduced a scientific journal HardwareX. It has featured many examples of applications of open-source hardware for scientific purposes. See also Computer numeric control (CNC) Fab lab Hardware backdoor HardwareX Open innovation Open manufacturing Open Source Ecology Open-source robotics Rapid prototyping Reuse RISC-V—an open-source computer instruction set architecture Simputer NVDLA References Further reading Building Open Source Hardware: DIY Manufacturing for Hackers and Makers by Alicia Gibb, Addison Wesley, 7 Dec. 2014, Open Source Hardware A Complete Guide by Gerardus Blokdyk, 5STARCooks, 15 Mar. 2021, Open Source Hardware Technology Paperback by Fouad Soliman, Sanaa A. Kamh, Karima A. Mahmoud, Publisher : Lap Lambert Academic Publishing, 24 Mar. 2020, Open-Source Lab: How to Build Your Own Hardware and Reduce Research Costs by Joshua M. Pearce, Elsevier, 17 Dec. 2013, External links Open Source Hardware Association Proposed Open Source Hardware (OSHW) Statement of Principles and Definition v1.0 Repositories OpenHardware.io Open Hardware Repository Free culture movement Open-source economics

Operating System (OS)

Operating system Wi-Fi support Operating system Wi-Fi support is the support in the operating system for Wi-Fi and usually consists of two pieces: driver level support, and configuration and management support. Driver support is usually provided by multiple manufacturers of the chip set hardware or end manufacturers. Also available are Unix clones such as Linux, sometimes through open source projects. Configuration and management support consists of software to enumerate, join, and check the status of available Wi-Fi networks. This also includes support for various encryption methods. These systems are often provided by the operating system backed by a standard driver model. In most cases, drivers emulate an Ethernet device and use the configuration and management utilities built into the operating system. In cases where built in configuration and management support is non-existent or inadequate, hardware manufacturers may include their own software to handle the respective tasks. Microsoft Windows Microsoft Windows has comprehensive driver-level support for Wi-Fi, the quality of which depends on the hardware manufacturer. Hardware manufactures almost always ship Windows drivers with their products. Windows ships with very few Wi-Fi drivers and depends on the original equipment manufacturers (OEMs) and device manufacturers to make sure users get drivers. Configuration and management depend on the version of Windows. Earlier versions of Windows, such as 98, ME and 2000 do not have built-in configuration and management support and must depend on software provided by the manufacturer Microsoft Windows XP has built-in configuration and management support. The original shipping version of Windows XP included rudimentary support which was dramatically improved in Service Pack 2. Support for WPA2 and some other security protocols require updates from Microsoft. Many hardware manufacturers include their own software and require the user to disable Windows’ built-in Wi-Fi support. Windows Vista, Windows 7, Windows 8, and Windows 10 have improved Wi-Fi support over Windows XP with a better interface and a suggestion to connect to a public Wi-Fi when no other connection is available. macOS and Classic Mac OS Apple was an early adopter of Wi-Fi, introducing its AirPort product line, based on the 802.11b standard, in July 1999. Apple later introduced AirPort Extreme, an implementation of 802.11g. All Apple computers, starting with the original iBook in 1999, either included AirPort 802.11 networking or were designed specifically to provide 802.11 networking with only the addition of the internal AirPort Card (or, later, an AirPort Extreme Card), connecting to the computer's built-in antennae. All Intel-based Macs either come with built-in AirPort Extreme or a slot for an AirPort card, and all portable Macs (all MacBooks and the earlier iBooks and PowerBooks) have included Wi-Fi for several years. In late 2006, Apple began shipping Macs with Broadcom Wi-Fi chips that also supported the Draft 802.11n standard, but this capability was disabled and Apple did not claim or advertise the hardware's capability until some time later when the draft had progressed further. At the January 2007 Macworld Expo, Apple announced that their computers would begin shipping with Draft 802.11n support. Systems shipped with this hidden capability can easily be unlocked through software, but due to the accounting requirements of Sarbanes-Oxley, Apple cannot freely add features to already-sold hardware and so must nominally sell an upgrade. This "upgrade" is included in the price of an AirPort Extreme Base Station for all computers owned by the purchaser, and Apple sells the "upgrade" separately (as the "AirPort Extreme 802.11n Enabler for Mac") for about US$2 in the United States and at similar prices elsewhere. Apple produces the operating system, the computer hardware, the accompanying drivers, AirPort Wi-Fi base stations, and configuration and management software, simplifying Wi-Fi integration, set-up, and maintenance (including security updates). The built-in configuration and management is integrated throughout many of the operating system's applications and utilities. Mac OS X has Wi-Fi support, including WPA2, and ships with drivers for all of Apple's current and past AirPort Extreme and AirPort cards. Many third-party manufacturers make compatible hardware along with the appropriate drivers which work with Mac OS X's built-in configuration and management software. Other manufacturers distribute their own software. Apple's older Mac OS 9 supported AirPort and AirPort Extreme as well, and drivers exist for other equipment from other manufacturers, providing Wi-Fi options for earlier systems not designed for AirPort cards. Versions of Mac OS before Mac OS 9 predate Wi-Fi and do not have any Wi-Fi support, although some third-party hardware manufacturers have made drivers and connection software that allows earlier OSes to use Wi-Fi. Open-source Unix-like systems Linux, FreeBSD and similar Unix-like clones have much coarser support for Wi-Fi. Due to the open source nature of these operating systems, many different standards have been developed for configuring and managing Wi-Fi devices. The open source nature also fosters open source drivers which have enabled many third party and proprietary devices to work under these operating systems. See Comparison of Open Source Wireless Drivers for more information on those drivers. Linux has patchy Wi-Fi support. This is especially true for older kernel versions, such as the 2.6 series, which is still widely used by enterprise distributions. Native drivers for many Wi-Fi chipsets are available either commercially or at no cost, although some manufacturers don't produce a Linux driver, only a Windows one. Consequently, many popular chipsets either don't have a native Linux driver at all, or only have a half-finished one. For these, the freely available NdisWrapper and its commercial competitor DriverLoader allow Windows x86 and 64 bit variants NDIS drivers to be used on x86-based Linux systems and 86_64 architectures as of January 6, 2005. As well as the lack of native drivers, some Linux distributions do not offer a convenient user interface and configuring Wi-Fi on them can be a clumsy and complicated operation compared to configuring wired Ethernet drivers. This is changing with the adoption of utilities such as NetworkManager and wicd that allow users to automatically switch between networks, without root access or command-line invocation of the traditional wireless tools. But some distributions include a large number of preinstalled drivers, like Ubuntu. FreeBSD has Wi-Fi support similar to Linux. FreeBSD 7.0 introduced full support for WPA and WPA2, although in some cases this is driver dependent. FreeBSD comes with drivers for many wireless cards and chipsets, including those made by Atheros, Intel Centrino, Ralink, Cisco, D-link, and Netgear, and provides support for others through the ports collection. FreeBSD also has "Project Evil", which provides the ability to use Windows x86 NDIS drivers on x86-based FreeBSD systems as NdisWrapper does on Linux, and Windows amd64 NDIS drivers on amd64-based systems. NetBSD, OpenBSD, and DragonFly BSD have Wi-Fi support similar to FreeBSD. Code for some of the drivers, as well as the kernel framework to support them, is mostly shared among the 4 BSDs. Haiku has preliminary Wi-Fi support since September 2009. Solaris and OpenSolaris have the Wireless Networking Project to provide Wi-Fi drivers and support. Android has built in support for WiFi, with it being preferred over Mobile telephony networks. Unison OS has built in support for embedded WiFi for a broad set of modules, with it being preferred over Mobile telephony networks (which also have off the shelf support). Mixed WiFi and Bluetooth for embedded systems is also provided. See also List of WLAN channels Wireless access point References External links Wi-Fi Alliance IEEE 802.11 Computer networking Wi-Fi

Operating System (OS)

Pinguy OS Pinguy OS is a free computer operating system (a Linux distribution) for x86-based PCs, based on Ubuntu Linux. General info Pinguy OS is an Ubuntu-based distribution with many applications and tweaks installed by default. Such software includes ZRam and Preload. According to Distrowatch.com Pinguy OS "features numerous user-friendly enhancements, out-of-the-box support for multimedia codecs and browser plugins, a heavily tweaked GNOME user interface with enhanced menus, panels and dockbars, and a careful selection of popular desktop applications for many common computing tasks." Although the distribution comes with many pre-installed applications, browser plugins, multimedia codecs and system utilities, many users could perceive this as unnecessary bloat, given that Ubuntu and many of its descendants come with a lot of useful software as well, without retaining a large memory and storage footprint. Features The following features are found in the Pinguy OS distribution: Installation: Graphical (GUI) Default Desktop: modified GNOME 3 (as of 14.04) Package Management: DEB (Ubuntu Software Center and Synaptic Package Manager installed) Processor Architecture: i686, x86-64 Journaled File Systems: ext3, ext4, JFS, ReiserFS, XFS Multilingual: Yes Release history The following is the release history for Pinguy OS Beta: The 6 month Pinguy OS releases will be missing features that will be in the final LTS, but the release will be very usable. Availability Pinguy OS is available in both 32-bit and 64-bit versions. See also Linux distribution Ubuntu Linux References External links Ubuntu derivatives X86-64 Linux distributions Linux distributions

Operating System (OS)

Architecture of Windows 9x The Windows 9x series of operating systems refers to the kernel which lies at the heart of Windows 9x. Its architecture is monolithic. The basic code is similar in function to MS-DOS. As a 16-/32-bit hybrid, it requires MS-DOS support to operate. Critical files Windows 95 boots using the following set of files: 32-bit shell and command line interpreter: SHELL.DLL and SHELL32.DLL – Shell API EXPLORER.EXE – Windows shell and file manager COMMAND.COM – command line shell executable Windows 95 Core: KERNEL32.DLL and KRNL386.EXE – Windows API for Windows resources ADVAPI32.DLL Functionality additional to the kernel. Includes functions for the Windows registry and shutdown and restart functions GDI32.DLL and GDI.EXE - Graphic device interface USER32.DLL and USER.EXE - GUI implementation COMMCTRL.DLL and COMCTL32.DLL - Common controls (user interface) DDEML.DLL Dynamic Data Exchange Management Library (DDEML) provides an interface that simplifies the task of adding DDE capability to an application MSGSRV32.EXE Acts as a 32-bit message server and will never appear in the Windows task list WIN.COM - responsible for loading the GUI and the Windows portion of the system Registry and other configuration files: SYSTEM.DAT, USER.DAT - contains the Windows Registry MSDOS.SYS - contains some low-level boot settings and resources such as disabling double-buffering and the GUI logo WIN.INI and SYSTEM.INI - configuration files from Windows 3.1, processed in Windows 9x also Virtual Machine Manager and configuration manager: VMM32.VXD - Virtual machine manager and default drivers. It takes over from io.sys as kernel Installable file System Manager: IFSHLP.SYS - enables Windows to make direct file system calls bypassing MS-DOS methods IFSMGR.VXD - 32-bit driver for the installable file system IOS.VXD I/O Supervisor that controls and manages all protected-mode file system and block device drivers MPREXE.EXE MPRSERV.DLL and MPR.DLL - Multiple Provider Router, required for network authentication and user profiles MSPWL32.DLL Password list management library Device drivers: IO.SYS - executable handling all of the basic functions, such as I/O routines and also serves as kernel until vmm32.vxd takes over HIMEM.SYS - DOS device driver which allows DOS programs to store data in extended memory via the Extended Memory Specification SYSTEM.DRV, MMSOUND.DRV, COMM.DRV , VGA.DRV, MOUSE.DRV, BIGMEM.DRV, KEYBOARD.DRV - 16-bit drivers CP 1252.NLS, CP 437.NLS, UNICODE.NLS, LOCALE.NLS - keyboard layouts RMM.PDR Real Mode Mapper Virtual Device The system may also use CONFIG.SYS, which contains settings and commands executed before loading the command interpreter) and AUTOEXEC.BAT, which is a batch file automatically executed after loading COMMAND.COM. However, these two files are not critical to the boot process, as IO.SYS contains a default setting for both, in case of absence from the system. In Windows ME, CONFIG.SYS and AUTOEXEC.BAT are not processed and LOGO.SYS may be used as a splash screen. Boot sequence The Windows 9x startup process consists of 6 phases. The first two of these steps are common to any operating system booting using the traditional combination of BIOS and Master Boot Record. Phase 1 - The ROM BIOS bootstrap process The ROM BIOS starts the execution at the physical memory address FFFF0h. During this phase, BIOS first executes the Power-on self-test, then checks for the existence of a boot disk on drive A. If it is not found in drive A, the ROM BIOS checks for a hard disk. If the computer has a Plug and Play BIOS, in addition, BIOS checks the RAM for I/O port addresses, interrupt lines and DMA channels for Plug and Play devices, disables found devices, creates maps of used and unused resources and re-enables devices. Phase 2 - The master boot record and boot sector The Master boot record is loaded at address 7C00h and loads the boot sector of the Windows Disk partition. The boot sector contains the disk boot program and BIOS Parameter Block table which searches for the location of the root directory and IO.SYS file, which then loads the IO.SYS file into memory. Phase 3 - IO.SYS file initialization IO.SYS initializes the minimal File Allocation Table driver and loads MSDOS.SYS into memory. It then displays "Starting Windows" depending on the BootDelay line in the MSDOS.SYS file. It then loads the LOGO.SYS file and displays a startup image on the screen. If the DRVSPACE.INI or DBLSPACE.INI file exists, it also loads drivers for compressed disks. Windows then attempts to open the registry file SYSTEM.DAT. If that fails, it attempts to open SYSTEM.DA0. If configured in MSDOS.SYS or in the registry, double buffering is also enabled. Phase 4 - CONFIG.SYS and real mode configuration Windows 95 to Windows 98 now analyze CONFIG.SYS and load MS-DOS real mode drivers. Windows ME ignores this. If the CONFIG.SYS file does not exist, the IO.SYS file loads the drivers IFSHLP.SYS, HIMEM.SYS and SETVER.EXE. Windows reserves all upper memory blocks for Windows 95 operating system use or for expanded memory. Windows 95 to Windows 98 execute COMMAND.COM to process AUTOEXEC.BAT. It loads terminate and stay resident programs into memory. Windows ME ignores this step, as Real Mode DOS support is disabled and TSRs being loaded can compromise system stability. Phase 5 - initialize drivers IO.SYS now runs WIN.COM. WIN.COM loads the VMM32.VXD file into memory or accesses it from the hard disk. This file contains the most important drivers and the 9x kernel. The real-mode virtual device driver loader checks for duplicate virtual device drivers that exist both in the Windows\System\Vmm32 folder and the VMM32.VXD file. In a case of duplicates, the driver in the Windows\System\Vmm32 directory will be loaded. Windows 95 to 98 now query real mode drivers calling INT 2Fh and search for drivers in registry entry HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD marked to be loaded as an external file. Vmm32 then analyzes the [386 Enh] section of the Windows\System.ini file and loads drivers listed there. Some important drivers are loaded even if they are not listed in the Windows Registry, SYSTEM.INI or in the Windows\System\Vmm32 directory. Once the real-mode virtual device drivers are loaded, driver initialization on Windows 95 to Windows 98 occurs. Vmm32 then switches the CPU from real mode to protected mode. The next step is the initialization of protected mode drivers, executed in three phases for each device: a critical part of initialization (while interrupts are disabled), device initialization (when file I/O is allowed) and InitComplete phase. After initialization of the display driver, Windows switches to graphical mode. Phase 6 - Win32 initialization Once all of the drivers are loaded, the Kernel32.dll, gdi32.dll, Gdi.exe, user32.dll, User.exe, shell32.dll and Explorer.exe files are loaded. The next step in the startup process is to load the network environment. The user is prompted to log on to the network that is configured. When a user logs on, their desktop settings are loaded from the registry, or the desktop configuration uses a default desktop. Windows then starts programs defined in the StartUp folder, WIN.INI and programs defined in registry keys Run, RunOnce, RunServices and RunServicesOnce inside the branches HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion and HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\. After each program in the RunOnce registry key is started, the program is removed from the key. Kernel The Windows 9x kernel is a 32-bit kernel with virtual memory. Drivers are provided by .VXD files or, since Windows 98, the newer WDM drivers can be used. However, the MS-DOS kernel stays resident in memory. Windows will use the old MS-DOS 16-bit drivers if they are installed, except on Windows Me. In Windows Me, DOS is still running, but Windows will ignore any attempt to load its device drivers when parsing the AUTOEXEC.BAT, and will move the environment variables that it still recognizes from the CONFIG.SYS into the Windows Registry. See also Architecture of Windows NT Microsoft Windows Caldera v. Microsoft WinGlue FreeWin95 References Further reading (xviii+856+vi pages, 3.5"-floppy) Errata: (NB. Also on MS-DOS 7+ HMA usage and \WINDOWS\IOS.LOG.) External links Monolithic kernels Windows 9x Windows 95 Windows 98 Windows ME

Operating System (OS)

Cray Operating System The Cray Operating System (COS) is a Cray Research operating system for its now-discontinued Cray-1 (1976) and Cray X-MP supercomputers. It succeeded the Chippewa Operating System (shipped with earlier Control Data Corporation CDC 6000 series and 7600 computer systems), and was the Cray main OS until replaced by UNICOS in the late 1980s. COS was delivered with Cray Assembly Language (CAL), Cray FORTRAN (CFT), and Pascal. Design As COS was written by ex-Control Data employees, its command language and internal organization bore strong resemblance to the CDC SCOPE operating system on the CDC 7600 and before that EXEC*8 from CDC's earlier ERA/Univac pedigree. User jobs were submitted to COS via front-end computers via a high-speed channel interface, and so-called station software. Front end stations were typically large IBM or Control Data mainframes. However the DEC VAX was also a very popular front-end. Interactive use of COS was possible through the stations, but most users simply submitted batch jobs. Disk-resident datasets used by a user program were 'local' to the individual job. Once a job completed, its local datasets would be released and space reclaimed. In order to retain the data between jobs, datasets had to be explicitly made 'permanent'. Magnetic tape datasets were also supported on Cray systems which were equipped with an I/O Subsystem. COS also provided job scheduling and checkpoint/restart facilities to manage large workloads, even across system downtimes (both scheduled and unscheduled.) Internally, COS was divided into a very small message-passing EXEC, and a number of System Task Processors (STP tasks). Each STP task was similar in nature to the peripheral processor programs in earlier Control Data operating systems, but since the Cray machines did not have peripheral processors, the main central processor executed the operating system code. List of STP tasks While the source for version 1.13 was released as public domain, 1.17 is available at archive.org. See also Cray Time Sharing System Timeline of operating systems References 1975 software Cray software Discontinued operating systems Supercomputer operating systems

Operating System (OS)

AROS Research Operating System AROS Research Operating System (AROS, pronounced "AR-OS") is a free and open-source multi media centric implementation of the AmigaOS 3.1 application programming interface (API). Designed to be portable and flexible. , Ports are available for x86-based and PowerPC-based personal computers (PCs) in native and hosted flavors, with other architectures in development. In a show of full circle development, AROS was also ported to the Motorola 68000 series (m68k) based Amiga 1200, and there is also an ARM port for the Raspberry Pi series. Name and identity AROS originally stood for Amiga Research Operating System, but to avoid any trademark issues with the Amiga name, it was changed to the recursive acronym AROS Research Operating System. The mascot of AROS is an anthropomorphic cat named Kitty, created by Eric Schwartz and officially adopted by the AROS Team in December 2, 2002. Used in the core AROS About and installer tools, it was also adopted by several AROS community sites and early distributions. Other AROS identifiable symbols and logos are based around the cat shape, such as the Icaros logo, which is a stylised cat's eye, or AFA (Aros for Amiga). Current status The project, begun in 1995, has over the years become an almost "feature complete" implementation of AmigaOS which, as of May 2017, only lacks a few areas of functionality. This was achieved by the efforts of a small team of developers. It can be installed on most IBM PC compatibles, and features native graphics drivers for video cards such as the GeForce range made by Nvidia. As of May 2007 USB keyboards and mice are also supported. AROS has been ported to the Sam440ep PowerPC board and a first test version for the Efika was released in 2009. While the OS is still lacking in applications, a few have been ported, including E-UAE, an emulation program that allows m68k-native AmigaOS applications to run. Some AROS-specific applications have also been written. AROS has TCP/IP networking support, and has available an experimental version of AMosaic web browser, for test purposes, among other Internet-related applications. The Poseidon USB stack has been ported to AROS. AROS is designed to be source-compatible with AmigaOS. On m68k Amiga hardware it is also binary-compatible, so binaries already compiled for AmigaOS 3 can be run on AROS. On x86 IA-32 32-bit platforms Janus-UAE, an enhanced E-UAE, integrates Amiga emulation directly into AROS to run AmigaOS m68k binaries nearly transparent to the user. , original AmigaOS 3 operating system files are needed for the emulation. The aim of AROS is to remain aloof of the legal and political spats that have plagued other AmigaOS implementations by being independent of hardware and of any central control. The de facto motto of AROS, "No schedule and rocking" both lampoons the infamous words "On Schedule and Rockin" from Amiga, Inc. CEO Bill McEwen, and declares a lack of the formal deadlines. A workable AmigaOS Kickstart clone for the Motorola 68000 processor was released on March 31, 2011 as part of a programming bounty. The memory requirement is 2 MB Chip RAM and 1 MB Fast RAM. This software is a complete free open-source alternative to AmigaOS. Distributions The main AROS system files can be downloaded in many flavors from the project website. These files are compiled straight from the SVN source tree at night time, and are available as nightly builds. Nightlies also include some third party applications to allow people using the system to perform some very basic tasks. For final/average user, like Linux, there are several distributions available: Icaros Desktop Since April 2009, the name VMWAros has been changed into "Icaros Desktop" to avoid ambiguities with any existing copyrighted Virtual Machine of any kind. Amiga 68K emulation integration, 3D acceleration for Nvidia cards and latest updates of applications can be found there. The latest version of Icaros Desktop is version 2.3 (released 22 December, 2020). Broadway Broadway is a distribution of AROS begun late 2009. The goal has been to provide a simple and complete introduction to what AROS has to offer. Also added was commercial software like a media center, a cloud storage service, and an appstore. Last version is 1.0 preview 5, released April 16, 2016. AspireOS AspireOS is a distribution, begun in 2011, by Nikos Tomatsidis, which is focused on Dell Latitude D520 and Acer Aspire One 110, 150 computers. Latest version is 2.2, codenamed "Obitus", released November 2018. AROS Vision AROS Vision is a native m68k distribution, which can run on both real hardware or in emulators like UAE. Apollo OS ApolloOS is an active m68k distribution, crafted specially for the Vampire V4 Standalone FPGA-based system. Influence on AmigaOS and MorphOS Haage & Partner used little parts of AROS source code for AmigaOS 3.5 and 3.9. Large parts of MorphOS (AmigaDOS, Intuition and more) have been ported from AROS. System requirements x86 CPU, newer than Intel 80486 (recommended minimum clockspeed of 700 MHz for desktops and 1 GHz for laptops/notebooks/netbooks) Floating Point Unit (FPU) 256 MB RAM See also Zune (GUI toolkit) AmigaOS 4 Emulator Virtual machine Porting Open source software MorphOS List of computing mascots :Category:Computing mascots References External links Icaros Desktop AROS Broadway AEROS AspireOS Wikibooks Hardware Compatibility Old AROS Bootable CD screenshots sourceforge.net – AROS download 1996 software Free software operating systems Hobbyist operating systems PowerPC operating systems X86 operating systems Microkernel-based operating systems Microkernels Window-based operating systems

Operating System (OS)

TOPS-20 The TOPS-20 operating system by Digital Equipment Corporation (DEC) was a proprietary OS used on some of DEC's 36-bit mainframe computers. The Hardware Reference Manual was described as for "DECsystem-10/DECSYSTEM-20 Processor" (meaning the DEC PDP-10 and the DECSYSTEM-20). TOPS-20 began in 1969 as the TENEX operating system of Bolt, Beranek and Newman (BBN) and shipped as a product by DEC starting in 1976. TOPS-20 is almost entirely unrelated to the similarly named TOPS-10, but it was shipped with the PA1050 TOPS-10 Monitor Calls emulation facility which allowed most, but not all, TOPS-10 executables to run unchanged. As a matter of policy, DEC did not update PA1050 to support later TOPS-10 additions except where required by DEC software. TOPS-20 competed with TOPS-10, ITS and WAITS—all of which were notable time-sharing systems for the PDP-10 during this timeframe. TENEX TOPS-20 was based upon the TENEX operating system, which had been created by Bolt Beranek and Newman for Digital's PDP-10 computer. After Digital started development of the KI-10 version of the PDP-10, an issue arose: by this point TENEX was the most popular customer-written PDP-10 operating systems, but it would not run on the new, faster KI-10s. To correct this problem, the DEC PDP-10 sales manager purchased the rights to TENEX from BBN and set up a project to port it to the new machine. In the end, very little of the original TENEX code remained, and Digital ultimately named the resulting operating system TOPS-20. PA1050 Some of what came with TOPS-20 was merely an emulation of the TOPS-10 Operating System's calls. These were known as UUO's, standing for Unimplemented User Operation, and were needed both for compilers, which were not 20-specific, to run, as well as user-programs written in these languages. The package that was mapped into a user's address space was named PA1050: PA as in PAT as in compatibility; 10 as in DEC or PDP 10; 50 as in a PDP 10 Model 50, 10/50, 1050. Sometimes PA1050 was referred to as PAT, a name that was a good fit to the fact that PA1050, "was simply unprivileged user-mode code" that "performed the requested action, using JSYS calls where necessary." TOPS-20 capabilities The major ways to get at TOPS-20 capabilities, and what made TOPS-20 important, were Commands entered via the command processor, EXEC.EXE JSYS (Jump to System) calls from MACro-language (.MAC) programs The "EXEC" accomplished its work primarily using internal code, including calls via JSYS requesting services from "GALAXY" components (e.g. spoolers) Command processor Rather advanced for its day were some TOPS-20-specific features: Command completion Dynamic help in the form of noise-words - typing DIR and then pressing the ESCape key resulted in DIRectory (of files) typing and pressing the key resulted in Information (about) One could then type to find out what operands were permitted/required. Pressing displays status information. Commands The following list of commands are supported by the TOPS-20 Command Processor. ACCESS ADVISE APPEND ARCHIVE ASSIGN ATTACH BACKSPACE BLANK BREAK BUILD CANCEL CLOSE COMPILE CONNECT CONTINUE COPY CREATE CREF CSAVE DAYTIME DDT DEASSIGN DEBUG DEFINE DELETE DEPOSIT DETACH DIRECTORY DISABLE DISCARD DISMOUNT EDIT ENABLE END-ACCESS EOF ERUN EXAMINE EXECUTE EXPUNGE FDIRECTORY FORK FREEZE GET HELP INFORMATION KEEP LOAD LOGIN LOGOUT MERGE MODIFY MOUNT PERUSE PLOT POP PRINT PUNCH PUSH R RECEIVE REENTER REFUSE REMARK RENAME RESET RETRIEVE REWIND RUN SAVE SEND SET SET HOST SKIP START SUBMIT SYSTAT TAKE TALK TDIRECTORY TERMINAL TRANSLATE TYPE UNATTACH UNDELETE UNKEEP UNLOAD VDIRECTORY JSYS features JSYS stands for Jump to SYStem. Operands were at times memory addresses. "TOPS-20 allows you to use 18-bit or 30-bit addresses. Some monitor calls require one kind, some the other; some calls accept either kind. Some monitor calls use only 18 bits to hold an address. These calls interpret 18-bit addresses as locations in the current section." Internally, files were first identified, using a GTJFN (Get Job File Number) JSYS, and then that JFN number was used to open (OPENF) and manipulate the file's contents. PCL (Programmable Command Language) PCL (Programmable Command Language) is a programming language that runs under TOPS-20. PCL source programs are, by default, stored with Filetype .PCL, and enable extending the TOPS-20 EXEC via a verb named DECLARE. Newly compiled commands then become functionally part of the EXEC. PCL language features PCL includes: flow control: DO While/Until, CASE/SELECT, IF-THEN-ELSE, GOTO character string operations (length, substring, concatenation) access to system information (date/time, file attributes, device characteristics) TOPS-20 today Paul Allen maintained several publicly accessible historic computer systems before his death, including an XKL TOAD-2 running TOPS-20. See also SDF Public Access Unix System. See also Time-sharing system evolution References "DIGITAL Computing Timeline". Further reading Storage Organization and Management in TENEX. Daniel L. Murphy. AFIPS Proceedings, 1972 FJCC. Implementation of TENEX on the KI10. Daniel L. Murphy. TENEX Panel Session, NCC 1974. Origins and Development of TOPS-20. Daniel L. Murphy, 1989. "TOPS-20 User's Guide." 1988. "DECSYSTEM-20 Assembly Language Guide." Frank da Cruz and Chris Ryland, 1980. "Running TOPS-20 V4.1 under the SIMH Emulator." External links Origins and Development of TOPS-20 is an excellent longer history. Panda TOPS-20 distribution. SDF Public Access TWENEX. SIMH Simulator capable of simulating the PDP-10 and running TOPS-20. Manuals for DEC 36-bit computers. PDP-10 Software Archive. 36-bits Forever. Request a login to Living Computers: Museum + Labs TOAD-2 running TOPS-20. DEC operating systems Time-sharing operating systems 1969 software

Operating System (OS)

Linux adoption Linux adoption is the adoption of Linux computer operating systems (OS) by households, nonprofit organizations, businesses, and governments. Many factors have resulted in the expanded use of Linux systems by traditional desktop users as well as operators of server systems, including the desire to minimize software costs, increase network security and support for open-source philosophical principles. In recent years several governments, at various levels, have enacted policies shifting state-owned computers to Linux from proprietary software regimes. In August 2010, Jeffrey Hammond, principal analyst at Forrester Research, declared, "Linux has crossed the chasm to mainstream adoption," a statement attested by the large number of enterprises that had transitioned to Linux during the late-2000s recession. In a company survey completed in the third quarter of 2009, 48% of surveyed companies reported using an open-source operating system. The Linux Foundation regularly releases publications regarding the Linux kernel, Linux OS distributions, and related themes. One such publication, "Linux Adoption Trends: A Survey of Enterprise End Users," is freely available upon registration. Traditionally, the term Linux adoption, refers to adoption of a Linux OS made for "desktop" computers, the original intended use (or adoption on servers, that is essentially the same form of OS). Adoption of that form on personal computers is still low relatively, while adoption of the Android operating system is very high. The term Linux adoption, often overlooks that operating system or other uses such as in Chrome OS that also use the Linux kernel (but have almost nothing else in common, not even the name – Linux – usually applied; while Android is the most popular variant – in fact the most popular operating system in the world). Linux adopters Outside of traditional web services, Linux powers many of the biggest Internet properties (e.g., Google, Amazon, Facebook, eBay, Twitter or Yahoo!). Hardware platforms with graphical user interface Linux is used on desktop computers, servers and supercomputers, as well as a wide range of devices. Desktop and Nettop computers and Laptops Measuring desktop adoption Because Linux desktop distributions are not usually distributed by retail sale, there are no sales numbers that indicate the number of users. One downloaded file may be used to create many CDs and each CD may be used to install the operating system on multiple computers. On the other hand, the file might be used only for a test and the installation erased soon after. Due to these factors estimates of current Linux desktop often rely on webpage hits by computers identifying themselves as running Linux. The use of these statistics has been criticized as unreliable and as underestimating Linux use. Using webpage hits as a measure, until 2008, Linux accounted for only about 1% of desktop market share, while Microsoft Windows operating systems held more than 90%. This might have been because Linux was not seen at that time as a direct replacement for Windows. , W3Counter estimated "Linux" web browser market share to be 4.63%, while "Android" versions 6, 5 and 4 combined (which is based on the Linux kernel) were estimated to be 33.77%. In September 2014 Pornhub released usage statistics of their website and reported 1.7% Linux users. The Unity game engine gathers user statistics and showed in March 2016 0.4% Linux users. Similarly, the Steam client tracks usage and reported in May 2015 around 1% Linux users. In April 2009, Aaron Seigo of KDE indicated that most web-page counter methods produce Linux adoption numbers that are far too low given the system's extensive penetration into non-North American markets, especially China. He stated that the North American-based web-measurement methods produce high Windows numbers and ignore the widespread use of Linux in other parts of the world. In estimating true worldwide desktop adoption and accounting for the Windows-distorted environment in the US and Canada he indicated that at least 8% of the world desktops run Linux distributions and possibly as high as 10–12% and that the numbers are rising quickly. Other commentators have echoed this same belief, noting that competitors are expending a lot of effort to discredit Linux, which is incongruent with a tiny market share: In May 2009, Preston Gralla, contributing editor to Computerworld.com, in reacting to the Net Applications web hit numbers showing that Linux use was over 1%, said that "Linux will never become an important desktop or notebook operating system". He reasoned that the upsurge in Linux desktop use recently seen was due to Linux netbooks, a trend he saw as already diminishing and which would be further eroded when Windows 7 became available (and indeed, Linux netbooks did fall by the wayside, though whether they were solely responsible for the upsurge in Linux usage is open to question). He concluded: "As a desktop operating system, Linux isn't important enough to think about. For servers, it's top-notch, but you likely won't use it on your desktop – even though it did finally manage to crack the 1% barrier after 18 years". In 2009, Microsoft then-CEO Steve Ballmer indicated that Linux had a greater desktop market share than Mac, stating that in recent years Linux had "certainly increased its share somewhat". Just under a third of all Dell netbook sales in 2009 had Linux installed. Caitlyn Martin, researching retail market numbers in the summer of 2010 also concluded that the traditional numbers mentioned for Linux desktop adoption were far too low: Reasons for adoption Reasons to change from other operating systems to Linux include better system stability, better malware protection, low or no cost, that most distributions come complete with application software and hardware drivers, simplified updates for all installed software, free software licensing, availability of application repositories and access to the source code. Linux desktop distributions also offer multiple desktop workspaces, greater customization, free and unlimited support through forums, and an operating system that doesn't slow down over time. Environmental reasons are also cited, as Linux operating systems usually do not come in boxes and other retail packaging, but are downloaded via the Internet. The lower system specifications also mean that older hardware can be kept in use instead of being recycled or discarded. Linux distributions also get security vulnerabilities patched much more quickly than non-free operating systems and improvements in Linux have been occurring at a faster rate than those in Windows. A report in The Economist in December 2007 said: Further investments have been made to improve desktop Linux usability since that 2007 report. Indian bulk computer purchaser the Electronics Corporation of Tamil Nadu (ELCOT) started recommending only Linux in June 2008. Following testing they stated: "ELCOT has been using SUSE Linux and Ubuntu Linux operating systems on desktop and laptop computers numbering over 2,000 during the past two years and found them far superior as compared to other operating systems, notably the Microsoft Windows Operating System." In many developing nations, such as China, where, due to widespread software piracy, Microsoft Windows can be easily obtained for free, Linux distributions are gaining a high level of adoption. Hence in these countries where there is essentially no cost barrier to obtaining proprietary operating systems, users are adopting Linux based on its merit, rather than on price. In January 2001, Microsoft then-CEO Bill Gates explained the attraction of adopting Linux in an internal memo that was released in the Comes vs Microsoft case. He said: Barriers to adoption The greatest barrier to Linux desktop adoption is probably that few desktop PCs come with it from the factory. A.Y. Siu asserted in 2006 that most people use Windows simply because most PCs come with Windows pre-installed; they didn't choose it. Linux has much lower market penetration because in most cases users have to install it themselves, a task that is beyond the capabilities of many PC users: "Most users won’t even use Windows restore CDs, let alone install Windows from scratch. Why would they install an unfamiliar operating system on their computers?" TechRepublic writer Jack Wallen expands on this barrier, saying in August 2008: Linus Torvalds stated, in his June 2012 interaction with students at Aalto University, that although Linux was originally conceived as a desktop system, that has been the only market where it has not flourished. He suggested that the key reason that keeps Linux from getting a substantial presence in the desktop market is that the average desktop user does not want to install an operating system, so getting manufacturers to sell computers with Linux pre-installed would be the missing piece to fulfill the vision of Linux in the desktop market. He added that Chromebooks, by shipping with the Linux-based Chrome OS, could provide the key turning point in such a transition, much like Android allowed Linux to spread in the mobile space. In September 2012, GNOME developer Michael Meeks also indicated that the main reason for the lack of adoption of Linux desktops is the lack of manufacturers shipping computers with it pre-installed, supporting Siu's arguments from six years earlier. Meeks also indicated that users wouldn't embrace desktop Linux until there is a wider range of applications and developers won't create that wider range of applications until there are more users, a classic Catch-22 situation. In an openSUSE survey conducted in 2007, 69.5% of respondents said they dual booted a Microsoft Windows operating system in addition to a Linux operating system. In early 2007 Bill Whyman, an analyst at Precursor Advisors, noted that "there still isn't a compelling alternative to the Microsoft infrastructure on the desktop." Application support, the quality of peripheral support, and end user support were at one time seen as the biggest obstacles to desktop Linux adoption. According to a 2006 survey by The Linux Foundation, these factors were seen as a "major obstacle" for 56%, 49%, and 33% of respondents respectively at that time. Application support The November 2006 Desktop Linux Client Survey identified the foremost barrier for deploying Linux desktops was that users were accustomed to Windows applications which had not been ported to Linux and which they "just can't live without". These included Microsoft Office, Adobe Photoshop, Autodesk AutoCAD, Microsoft Project, Visio and Intuit QuickBooks. This creates a chicken or the egg situation where developers make programs for Windows due to its market share, and consumers use Windows due to availability of said programs. In a DesktopLinux.com survey conducted in 2007, 72% of respondents said they used ways to run Windows applications on Linux. 51% of respondents to the 2006 Linux Foundation survey, believed that cross-distribution Linux desktop standards should be the top priority for the Linux desktop community, highlighting the fact that the fragmented Linux market is preventing application vendors from developing, distributing and supporting the operating system. In May 2008, Gartner predicted that "version control and incompatibilities will continue to plague open-source OSs and associated middleware" in the 2013 timeframe. By 2008, the design of Linux applications and the porting of Windows and Apple applications had progressed to the point where it was difficult to find an application that did not have an equivalent for Linux, providing adequate or better capabilities. An example of application progress can be seen comparing the main productivity suite for Linux, OpenOffice.org, to Microsoft Office. With the release of OpenOffice.org 3.0 in October 2008 Ars Technica assessed the two: Peripheral support In the past the availability and quality of open source device drivers were issues for Linux desktops. Particular areas which were lacking drivers included printers as well as wireless and audio cards. For example, in early 2007, Dell did not sell specific hardware and software with Ubuntu 7.04 computers, including printers, projectors, Bluetooth keyboards and mice, TV tuners and remote controls, desktop modems and Blu-ray drives, due to incompatibilities at that time, as well as legal issues. By 2008, most Linux hardware support and driver issues had been adequately addressed. In September 2008, Jack Wallen's assessment was: End-user support Some critics have stated that compared to Windows, Linux is lacking in end-user support. Linux has traditionally been seen as requiring much more technical expertise. Dell's website described open source software as requiring intermediate or advanced knowledge to use. In September 2007, the founder of the Ubuntu project, Mark Shuttleworth, commented that "it would be reasonable to say that this is not ready for the mass market." In October 2004, Chief Technical Officer of Adeptiva Linux, Stephan February, noted at that time that Linux was a very technical software product, and few people outside the technical community were able to support consumers. Windows users are able to rely on friends and family for help, but Linux users generally use discussion boards, which can be uncomfortable for consumers. In 2005, Dominic Humphries summarized the difference in user tech support: More recently critics have found that the Linux user support model, using community-based forum support, has greatly improved. In 2008 Jack Wallen stated: In addressing the question of user support, Manu Cornet said: Other factors Linux's credibility has also been under attack at times, but as Ron Miller of LinuxPlanet points out: There is continuing debate about the total cost of ownership of Linux, with Gartner warning in 2005 that the costs of migration may exceed the cost benefits of Linux. Gartner reiterated the warning in 2008, predicting that "by 2013, a majority of Linux deployments will have no real software total cost of ownership (TCO) advantage over other operating systems." However, in the Comes v. Microsoft lawsuit, Plaintiff's exhibit 2817 revealed that Microsoft successfully lobbied Gartner for changing their TCO model in favour of Microsoft in 1998. Organizations that have moved to Linux have disagreed with these warnings. Sterling Ball, CEO of Ernie Ball, the world's leading maker of premium guitar strings and a 2003 Linux adopter, said of total cost of ownership arguments: "I think that's propaganda...What about the cost of dealing with a virus? We don't have 'em...There's no doubt that what I'm doing is cheaper to operate. The analyst guys can say whatever they want." In the SCO-Linux controversies, the SCO Group had alleged that UNIX source code donated by IBM was illegally incorporated into Linux. The threat that SCO might be able to legally assert ownership of Linux initially caused some potential Linux adopters to delay that move. The court cases bankrupted SCO in 2007 after it lost its four-year court battle over the ownership of the UNIX copyrights. SCO's case had hinged on showing that Linux included intellectual property that had been misappropriated from UNIX, but the case failed when the court discovered that Novell and not SCO was the rightful owner of the copyrights. During the legal process, it was revealed that SCO's claims about Linux were fraudulent and that SCO's internal source code audits had showed no evidence of infringement. A rival operating system vendor, Green Hills Software, has called the open source paradigm of Linux "fundamentally insecure". The US Army does not agree that Linux is a security problem. Brigadier General Nick Justice, the Deputy Program Officer for the Army's Program Executive Office, Command, Control and Communications Tactical (PEO C3T), said in April 2007: Netbooks In 2008, Gartner analysts predicted that mobile devices like Netbooks with Linux could potentially break the dominance of Microsoft's Windows as operating system provider, as the netbook concept focuses on OS-agnostic applications built as Web applications and browsing. Until 2008 the netbook market was dominated by Linux-powered devices; this changed in 2009 after Windows XP became available as option. One of the reasons given was that many customers returned Linux-based netbooks as they were still expecting a Windows-like environment, despite the netbook vision: a web-surfing and web-application device. Web thin clients In 2011, Google introduced the Chromebook, a web thin client running the Linux-based Chrome OS, with the ability to use web applications and remote desktop in to other computers running Windows, Mac OS X, a traditional Linux distribution or Chrome OS, using Chrome Remote Desktop. In 2012 Google and Samsung introduced the first version of the Chromebox, a small-form-factor desktop equivalent to the Chromebook. By 2013, Chromebooks had captured 20–25% of the sub-$300 US laptop market. Mobile devices Note: The term "mobile devices" in the computing context refers to cellphones and tablets; , the term does not include regular laptops, despite the fact that they have always been designed to be mobile. Android, which is based on Linux and is open source, is the most popular mobile platform. During the second quarter of 2013, 79.3% of smartphones sold worldwide were running Android. Android tablets are also available. Discontinued Linux-based mobile operating systems Firefox OS was another open source Linux-based mobile operating system, which has now been discontinued. Nokia previously produced some phones running a variant of Linux (e.g. the Nokia N900), but in 2013, Nokia's handset division was bought by Microsoft. Other embedded systems with graphical user interface Smartphones are gradually replacing these kinds of embedded devices, but they still exist. An example are the Portable media players. Some of the OEM firmware is Linux based. A community-driven fully free and open-source project is Rockbox. In-vehicle infotainment hardware usually involves some kind of display, either built into the Dashboard or additional displays. The GENIVI Alliance works on a Linux-based open platform to run the IVI. It may have an interface to some values delivered by the Engine control unit but is albeit completely separate system. There will be a special variant of Tizen for IVI, different for the Tizen for smartphones in several regards. Hardware platforms without graphical user interface Embedded systems without graphical user interface Linux is often used in various single- or multi-purpose computer appliances and embedded systems. Customer-premises equipment are a group of devices that are embedded and have no graphical user interface in the common sense. Some are remotely operated via Secure Shell or via some Web-based user interface running on some lightweight web server software. Most of the OEM firmware is based on the Linux kernel and other free and open-source software, e.g. Das U-Boot and Busybox. There are also a couple of community driven projects, e.g. OpenWrt. Smaller scale embedded network-attached storage-devices are also mostly Linux-driven. Servers Linux became popular in the Internet server market particularly due to the LAMP software bundle. In September 2008 Steve Ballmer (Microsoft CEO) claimed 60% of servers run Linux and 40% run Windows Server. According to IDC's report covering Q2 2013, Linux was up to 23.2% of worldwide server revenue although this does compensate for the potential price disparity between Linux and non-Linux servers. In May 2014, W3Techs estimated that 67.5% of the top 10 million (according to Alexa) websites run some form of Unix, and Linux is used by at least 57.2% of all those websites which use Unix. Web servers Linux-based solution stacks come with all the general advantages and benefits of free and open-source software. Some more commonly known examples are: LAMP MEAN stack According to the Netcraft, , nginx had the highest market share. LDAP servers There are various freely available implementations of LDAP servers. Additionally, Univention Corporate Server, as an integrated management system based on Debian, supports the functions provided by Microsoft Active Directory for the administration of computers running Microsoft Windows. Routers Free routing software available for Linux includes BIRD, B.A.T.M.A.N., Quagga and XORP. Whether on Customer-premises equipment, on Personal computer hardware or on server-hardware, the mainline Linux kernel or an adapted highly optimized Linux kernel is capable of doing routing at rates that are limited by the hardware bus throughput. Supercomputers Linux is the most popular operating system among supercomputers due to the general advantages and benefits of free and open-source software, like superior performance, flexibility, speed and lower costs. In November 2008 Linux held an 87.8 percent share of the world's top 500 supercomputers. As of November 2021, the operating systems used on the world's top 500 supercomputers were: In January 2010, Weiwu Hu, chief architect of the Loongson family of CPUs at the Institute of Computing Technology, which is part of the Chinese Academy of Sciences, confirmed that the new Dawning 6000 supercomputer will use Chinese-made Loongson processors and will run Linux as its operating system. The most recent supercomputer the organization built, the Dawning 5000a, which was first run in 2008, used AMD chips and ran Windows HPC Server 2008. Advocacy Many organizations advocate for Linux adoption. The foremost of these is the Linux Foundation which hosts and sponsors the key kernel developers, manages the Linux trademark, manages the Open Source Developer Travel Fund, provides legal aid to open source developers and companies through the Linux Legal Defense Fund, sponsors kernel.org and also hosts the Patent Commons Project. The International Free and Open Source Software Foundation (iFOSSF) is a nonprofit organization based in Michigan, USA dedicated to accelerating and promoting the adoption of FOSS worldwide through research and civil society partnership networks. The Open Invention Network was formed to protect vendors and customers from patent royalty fees while using OSS. Other advocates for Linux include: IBM through its Linux Marketing Strategy Linux User Groups Asian Open Source Centre (AsiaOSC) The Brazilian government, under president Luiz Inácio Lula da Silva Software Livre Brasil, a Brazilian organization promoting Linux adoption in schools, public departments, commerce, industry and personal desktops. FOSS: Free and Open Source Software Foundations of India and China. History Gartner claimed that Linux-powered personal computers accounted for 4% of unit sales in 2008. However, it is common for users to install Linux in addition to (as a dual boot arrangement) or in place of a factory-installed Microsoft Windows operating system. Timeline 1983 (September): GNU project announced publicly 1991 (September): First version of the Linux kernel released to the Internet mid-1990s: Linux runs on cluster computers at NASA and elsewhere late 1990s: Dell, IBM and Hewlett-Packard offer commercial support for Linux on their hardware; Red Hat and VA Linux have initial public offerings 1999: EmperorLinux started shipping specially configured laptops running modified Linux distributions to ensure usability 2001 (second quarter): Linux server unit shipments recorded a 15% annual growth rate 2004: Linux shipped on approximately 50% of the worldwide server blade units, and 20% of all rack-optimized servers 2005: System76, a Linux-only computer OEM, starts selling Ubuntu pre-installed on laptops and desktops. 2007 Dell announced it would ship select models with Ubuntu Linux pre-installed ZaReason is founded as a Linux only hardware OEM. Lenovo announced it would ship select models with SUSE Linux Enterprise Desktop pre-installed HP announced that it would begin shipping computers preinstalled with Red Hat Enterprise Linux in Australia ASUS launched the Linux-based ASUS Eee PC 2008 Dell announced it would begin shipping Ubuntu-based computers to Canada and Latin America. Dell began shipping systems with Ubuntu pre-installed in China. Acer launched the Linux-based Acer Aspire One. In June 2008, the Electronics Corporation of Tamil Nadu (ELCOT), a bulk computer buyer for students in the Indian state of Tamil Nadu, decided to switch entirely to supplying Linux after Microsoft attempted to use its monopoly position to sell the organization Windows bundled with Microsoft Office. ELCOT declined the offer stating "Any such bundling could result in serious exploitation of the consumer." In August 2008, IBM cited market disillusionment with Microsoft Vista in announcing a new partnership arrangement with Red Hat, Novell and Canonical to offer "Microsoft-free" personal computers with IBM application software, including Lotus Notes and Lotus Symphony. 2009 In January 2009, the New York Times stated: "More than 10 million people are estimated to run Ubuntu today". In mid-2009, Asus, as part of its It's better with Windows campaign, stopped offering Linux, for which they received strong criticism. The company claimed that competition from other netbook makers drove them to offer only Windows XP. Writing in May 2010 ComputerWorld columnist Steven J. Vaughan-Nichols said "I'm sure that the real reason is Microsoft has pressured Asus into abandoning Linux. On ASUS' site, you'll now see the slogan 'ASUS recommends Windows 7' proudly shown. Never mind that, while Windows 7 is a good operating system, Windows 7 is awful on netbooks." In May 2009, Fedora developer Jef Spaleta estimated on the basis of IP addresses of update downloads and statistics from the voluntary user hardware registration service Smolt that there are 16 million Fedora systems in use. No effort was made to estimate how much the Fedora installed base overlaps with other Linux distributions (enthusiasts installing many distributions on the same system). In June 2009, ZDNet reported "Worldwide, there are 13 million active Ubuntu users with use growing faster than any other distribution." 2010 In April 2010, Chris Kenyon, vice president for OEM at Canonical Ltd., estimated that there were 12 million Ubuntu users. In June 2010, a Quebec Superior Court Judge Denis Jacques ruled that the provincial government broke the law when it spent Cdn$720,000, starting in the fall of 2006 to migrate 800 government workstations to Microsoft Windows Vista and Office 2007 without carrying out a "serious and documented search" for alternatives. The search for alternatives was legally required for any expenditures over Cdn$25,000. The court case was brought by Savoir Faire Linux, a small Montreal-based company that had hoped to bid Linux software to replace the government's aging Windows XP. The judge dismissed the government's contention that Microsoft software was chosen because employees were already familiar with Windows and that switching to a different operating system would have cost more. In October 2010, a statistics company stated that Android, Google's version of Linux for smartphones (and tablets), had become the most popular operating system among new buyers. 2012 In November 2012, Top500.org's November 2012 list has all Top 10 Supercomputers as running a distribution of Linux as their Operating System. 2013 In February 2013, Dice and the Linux Foundation released a survey that showed Linux skills in high demand among employers. Valve announces its Linux-based SteamOS for video game consoles. Supercomputers, Japan's bullet trains, traffic control, Toyota IVI, NYSE, CERN, FAA air traffic control, nuclear submarines and top websites all use Linux. In December 2013, the city of Munich announced that it successfully migrated 12,000 of its 15,000 computers to LiMux Linux and that the savings in 2013 alone were about 10 million euros. 2014 In September 2014, the Italian city of Turin, the capital of Piedmont, decided to switch to Linux. In October 2014, the city of Gummersbach announced that their IT infrastructure now is based on 300 thin clients and 6 servers that run SuSe Linux. June 2014, France's National Gendarmerie has completed the migration of 65,000 to Linux "GendBuntu". In November 2014 Purism was founded as an OEM Linux manufacturer. 2017 In November 2017, all 500 of the world's top supercomputers ran Linux. 2018 In April 2018, Microsoft announced Azure Sphere, a Linux-based operating system for Internet of Things applications. In May 2018, pre-orders began for Atari VCS, a gaming console that is powered by the Linux kernel. 2019 In May 2019, Microsoft announced Windows Subsystem for Linux 2, which will rely on a pre-installed Linux kernel built by Microsoft. This marks the first time that the Linux kernel has shipped with a Microsoft operating system. In May 2019, South Korea announced that it was looking to migrate its major government systems to Linux, due to the pending end of support for Windows 7. 2021 In January 2021 the government of the Argentinian province of Misiones announced that it had developed , a distribution based on the Devuan operating system, specially designed for government offices. In February 2021 Linux was first used on Mars when NASA's Perseverance rover landed on 18 February. See also References External links O/S market share monthly estimations, based on internet traffic Operating System Market Share Worldwide | StatCounter Global Stats LinuxWorld: What's Driving Global Linux Adoption? OSDL Desktop Linux Client Survey Canadian Provincial Medical Association To Use Open Source Platform For EMR Project IDC: Latin America Linux Migration Trends 2005 OSDL Claims Linux Making Major Gains in Global Retail Sector Linux Advocacy mini-HOWTO Measuring total cost of ownership Gartner: Open source will quietly take over IDC: Linux-Related Spending Could Top $49B by 2011 Red Hat – Open Source Activity Map Linux Linux-based devices Operating system advocacy Technological change

Operating System (OS)

Windows 7 Windows 7 is a major release of the Windows NT operating system developed by Microsoft. It was released to manufacturing on July 22, 2009, and became generally available on October 22, 2009. It is the successor to Windows Vista, released nearly three years earlier. It remained an operating system for use on personal computers, including home and business desktops, laptops, tablet PCs and media center PCs, and itself was replaced in November 2012 by Windows 8, the name spanning more than three years of the product. Until April 9, 2013, Windows 7 original release includes updates and technical support, after which installation of Service Pack 1 is required for users to receive support and updates. Windows 7's server counterpart, Windows Server 2008 R2, was released at the same time. The last supported version of Windows based on this operating system was released on July 1, 2011, entitled Windows Embedded POSReady 7. Extended support ended on January 14, 2020, over ten years after the release of Windows 7, after which the operating system ceased receiving further support. A support program is currently available for enterprises, providing security updates for Windows 7 for up to four years since the official end of life. However, Windows Embedded POSReady 7, the last Windows 7 variant, continued to receive security updates until October 2021. Windows 7 was intended to be an incremental upgrade to Microsoft Windows, addressing Windows Vista's poor critical reception while maintaining hardware and software compatibility. Windows 7 continued improvements on Windows Aero user interface with the addition of a redesigned taskbar that allows pinned applications, and new window management features. Other new features were added to the operating system, including libraries, the new file-sharing system HomeGroup, and support for multitouch input. A new "Action Center" was also added to provide an overview of system security and maintenance information, and tweaks were made to the User Account Control system to make it less intrusive. Windows 7 also shipped with updated versions of several stock applications, including Internet Explorer 8, Windows Media Player, and Windows Media Center. Unlike Vista, Windows 7 received critical acclaim, with critics considering the operating system to be a major improvement over its predecessor because of its improved performance, its more intuitive interface, fewer User Account Control popups, and other improvements made across the platform. Windows 7 was a major success for Microsoft; even before its official release, pre-order sales for the operating system on the online retailer Amazon.com had surpassed previous records. In just six months, over 100 million copies had been sold worldwide, increasing to over 630 million licenses by July 2012. By January 2018, Windows 10 surpassed Windows 7 as the most popular version of Windows worldwide. , 12.76% of traditional PCs running Windows are running Windows 7. It still remains popular in countries such as Syria, China, India, and Venezuela. Development history Originally, a version of Windows codenamed "Blackcomb" was planned as the successor to Windows XP and Windows Server 2003 in 2000. Major features were planned for Blackcomb, including an emphasis on searching and querying data and an advanced storage system named WinFS to enable such scenarios. However, an interim, minor release, codenamed "Longhorn," was announced for 2003, delaying the development of Blackcomb. By the middle of 2003, however, Longhorn had acquired some of the features originally intended for Blackcomb. After three major malware outbreaks—the Blaster, Nachi, and Sobig worms—exploited flaws in Windows operating systems within a short time period in August 2003, Microsoft changed its development priorities, putting some of Longhorn's major development work on hold while developing new service packs for Windows XP and Windows Server 2003. Development of Longhorn (Windows Vista) was also restarted, and thus delayed, in August 2004. A number of features were cut from Longhorn. Blackcomb was renamed Vienna in early 2006, and was later canceled in 2007 due to the scope of the project. When released, Windows Vista was criticized for its long development time, performance issues, spotty compatibility with existing hardware and software at launch, changes affecting the compatibility of certain PC games, and unclear assurances by Microsoft that certain computers shipping with XP before launch would be "Vista Capable" (which led to a class-action lawsuit), among other critiques. As such, the adoption of Vista in comparison to XP remained somewhat low. In July 2007, six months following the public release of Vista, it was reported that the next version of Windows would then be codenamed Windows 7, with plans for a final release within three years. Bill Gates, in an interview with Newsweek, suggested that Windows 7 would be more "user-centric". Gates later said that Windows 7 would also focus on performance improvements. Steven Sinofsky later expanded on this point, explaining in the Engineering Windows 7 blog that the company was using a variety of new tracing tools to measure the performance of many areas of the operating system on an ongoing basis, to help locate inefficient code paths and to help prevent performance regressions. Senior Vice President Bill Veghte stated that Windows Vista users migrating to Windows 7 would not find the kind of device compatibility issues they encountered migrating from Windows XP. An estimated 1,000 developers worked on Windows 7. These were broadly divided into "core operating system" and "Windows client experience", in turn organized into 25 teams of around 40 developers on average. In October 2008, it was announced that Windows 7 would also be the official name of the operating system. There has been some confusion over naming the product Windows 7, while versioning it as 6.1 to indicate its similar build to Vista and increase compatibility with applications that only check major version numbers, similar to Windows 2000 and Windows XP both having 5.x version numbers. The first external release to select Microsoft partners came in January 2008 with Milestone 1, build 6519. Speaking about Windows 7 on October 16, 2008, Microsoft CEO Steve Ballmer confirmed compatibility between Windows Vista and Windows 7, indicating that Windows 7 would be a refined version of Windows Vista. At PDC 2008, Microsoft demonstrated Windows 7 with its reworked taskbar. On December 27, 2008, the Windows 7 Beta was leaked onto the Internet via BitTorrent. According to a performance test by ZDNet, Windows 7 Beta beat both Windows XP and Vista in several key areas, including boot and shutdown time and working with files, such as loading documents. Other areas did not beat XP, including PC Pro benchmarks for typical office activities and video editing, which remain identical to Vista and slower than XP. On January 7, 2009, the x64 version of the Windows 7 Beta (build 7000) was leaked onto the web, with some torrents being infected with a trojan. At CES 2009, Microsoft CEO Steve Ballmer announced the Windows 7 Beta, build 7000, had been made available for download to MSDN and TechNet subscribers in the format of an ISO image. The stock wallpaper of the beta version contained a digital image of the Betta fish. The release candidate, build 7100, became available for MSDN and TechNet subscribers, and Connect Program participants on April 30, 2009. On May 5, 2009, it became available to the general public, although it had also been leaked onto the Internet via BitTorrent. The release candidate was available in five languages and expired on June 1, 2010, with shutdowns every two hours starting March 1, 2010. Microsoft stated that Windows 7 would be released to the general public on October 22, 2009, less than three years after the launch of its predecessor. Microsoft released Windows 7 to MSDN and Technet subscribers on August 6, 2009. Microsoft announced that Windows 7, along with Windows Server 2008 R2, was released to manufacturing in the United States and Canada on July 22, 2009. Windows 7 RTM is build 7600.16385.090713-1255, which was compiled on July 13, 2009, and was declared the final RTM build after passing all Microsoft's tests internally. Features New and changed Among Windows 7's new features are advances in touch and handwriting recognition, support for virtual hard disks, improved performance on multi-core processors, improved boot performance, DirectAccess, and kernel improvements. Windows 7 adds support for systems using multiple heterogeneous graphics cards from different vendors (Heterogeneous Multi-adapter), a new version of Windows Media Center, a Gadget for Windows Media Center, improved media features, XPS Essentials Pack and Windows PowerShell being included, and a redesigned Calculator with multiline capabilities including Programmer and Statistics modes along with unit conversion for length, weight, temperature, and several others. Many new items have been added to the Control Panel, including ClearType Text Tuner Display Color Calibration Wizard, Gadgets, Recovery, Troubleshooting, Workspaces Center, Location and Other Sensors, Credential Manager, Biometric Devices, System Icons, and Display. Windows Security Center has been renamed to Windows Action Center (Windows Health Center and Windows Solution Center in earlier builds), which encompasses both security and maintenance of the computer. ReadyBoost on 32-bit editions now supports up to 256 gigabytes of extra allocation. Windows 7 also supports images in RAW image format through the addition of Windows Imaging Component-enabled image decoders, which enables raw image thumbnails, previewing and metadata display in Windows Explorer, plus full-size viewing and slideshows in Windows Photo Viewer and Windows Media Center. Windows 7 also has a native TFTP client with the ability to transfer files to or from a TFTP server. The taskbar has seen the biggest visual changes, where the old Quick Launch toolbar has been replaced with the ability to pin applications to the taskbar. Buttons for pinned applications are integrated with the task buttons. These buttons also enable Jump Lists to allow easy access to common tasks, and files frequently used with specific applications. The revamped taskbar also allows the reordering of taskbar buttons. To the far right of the system clock is a small rectangular button that serves as the Show desktop icon. By default, hovering over this button makes all visible windows transparent for a quick look at the desktop. In touch-enabled displays such as touch screens, tablet PCs, etc., this button is slightly (8 pixels) wider in order to accommodate being pressed by a finger. Clicking this button minimizes all windows, and clicking it a second time restores them. Window management in Windows 7 has several new features: Aero Snap maximizes a window when it is dragged to the top, left, or right of the screen. Dragging windows to the left or right edges of the screen allows users to snap software windows to either side of the screen, such that the windows take up half the screen. When a user moves windows that were snapped or maximized using Snap, the system restores their previous state. Snap functions can also be triggered with keyboard shortcuts. Aero Shake hides all inactive windows when the active window's title bar is dragged back and forth rapidly. Windows 7 includes 13 additional sound schemes, titled Afternoon, Calligraphy, Characters, Cityscape, Delta, Festival, Garden, Heritage, Landscape, Quirky, Raga, Savanna, and Sonata. Internet Spades, Internet Backgammon and Internet Checkers, which were removed from Windows Vista, were restored in Windows 7. Users are able to disable or customize many more Windows components than was possible in Windows Vista. New additions to this list of components include Internet Explorer 8, Windows Media Player 12, Windows Media Center, Windows Search, and Windows Gadget Platform. A new version of Microsoft Virtual PC, newly renamed as Windows Virtual PC was made available for Windows 7 Professional, Enterprise, and Ultimate editions. It allows multiple Windows environments, including Windows XP Mode, to run on the same machine. Windows XP Mode runs Windows XP in a virtual machine, and displays applications within separate windows on the Windows 7 desktop. Furthermore, Windows 7 supports the mounting of a virtual hard disk (VHD) as a normal data storage, and the bootloader delivered with Windows 7 can boot the Windows system from a VHD; however, this ability is only available in the Enterprise and Ultimate editions. The Remote Desktop Protocol (RDP) of Windows 7 is also enhanced to support real-time multimedia application including video playback and 3D games, thus allowing use of DirectX 10 in remote desktop environments. The three application limit, previously present in the Windows Vista and Windows XP Starter Editions, has been removed from Windows 7. All editions include some new and improved features, such as Windows Search, Security features, and some features new to Windows 7, that originated within Vista. Optional BitLocker Drive Encryption is included with Windows 7 Ultimate and Enterprise. Windows Defender is included; Microsoft Security Essentials antivirus software is a free download. All editions include Shadow Copy, which—every day or so—System Restore uses to take an automatic "previous version" snapshot of user files that have changed. Backup and restore have also been improved, and the Windows Recovery Environment—installed by default—replaces the optional Recovery Console of Windows XP. A new system known as "Libraries" was added for file management; users can aggregate files from multiple folders into a "Library." By default, libraries for categories such as Documents, Pictures, Music, and Video are created, consisting of the user's personal folder and the Public folder for each. The system is also used as part of a new home networking system known as HomeGroup; devices are added to the network with a password, and files and folders can be shared with all other devices in the HomeGroup, or with specific users. The default libraries, along with printers, are shared by default, but the personal folder is set to read-only access by other users, and the Public folder can be accessed by anyone. Windows 7 includes improved globalization support through a new Extended Linguistic Services API to provide multilingual support (particularly in Ultimate and Enterprise editions). Microsoft also implemented better support for solid-state drives, including the new TRIM command, and Windows 7 is able to identify a solid-state drive uniquely. Native support for USB 3.0 is not included because of delays in the finalization of the standard. At WinHEC 2008 Microsoft announced that color depths of 30-bit and 48-bit would be supported in Windows 7 along with the wide color gamut scRGB (which for HDMI 1.3 can be converted and output as xvYCC). The video modes supported in Windows 7 are 16-bit sRGB, 24-bit sRGB, 30-bit sRGB, 30-bit with extended color gamut sRGB, and 48-bit scRGB. For developers, Windows 7 includes a new networking API with support for building SOAP-based web services in native code (as opposed to .NET-based WCF web services), new features to simplify development of installation packages and shorten application install times. Windows 7, by default, generates fewer User Account Control (UAC) prompts because it allows digitally signed Windows components to gain elevated privileges without a prompt. Additionally, users can now adjust the level at which UAC operates using a sliding scale. Removed Certain capabilities and programs that were a part of Windows Vista are no longer present or have been changed, resulting in the removal of certain functionalities; these include the classic Start Menu user interface, some taskbar features, Windows Explorer features, Windows Media Player features, Windows Ultimate Extras, Search button, and InkBall. Four applications bundled with Windows Vista—Windows Photo Gallery, Windows Movie Maker, Windows Calendar and Windows Mail—are not included with Windows 7 and were replaced by Windows Live-branded versions as part of the Windows Live Essentials suite. Editions Windows 7 is available in six different editions, of which the Home Premium, Professional, and Ultimate were available at retail in most countries, and as pre-loaded software on most new computers. Home Premium and Professional were aimed at home users and small businesses respectively, while Ultimate was aimed at enthusiasts. Each edition of Windows 7 includes all of the capabilities and features of the edition below it, and adds additional features oriented towards their market segments; for example, Professional adds additional networking and security features such as Encrypting File System and the ability to join a domain. Ultimate contained a superset of the features from Home Premium and Professional, along with other advanced features oriented towards power users, such as BitLocker drive encryption; unlike Windows Vista, there were no "Ultimate Extras" add-ons created for Windows 7 Ultimate. Retail copies were available in "upgrade" and higher-cost "full" version licenses; "upgrade" licenses require an existing version of Windows to install, while "full" licenses can be installed on computers with no existing operating system. The remaining three editions were not available at retail, of which two were available exclusively through OEM channels as pre-loaded software. The Starter edition is a stripped-down version of Windows 7 meant for low-cost devices such as netbooks. In comparison to Home Premium, Starter has reduced multimedia functionality, does not allow users to change their desktop wallpaper or theme, disables the "Aero Glass" theme, does not have support for multiple monitors, and can only address 2GB of RAM. Home Basic was sold only in emerging markets, and was positioned in between Home Premium and Starter. The highest edition, Enterprise, is functionally similar to Ultimate, but is only sold through volume licensing via Microsoft's Software Assurance program. All editions aside from Starter support both IA-32 and x86-64 architectures, Starter only supports 32-bit systems. Retail copies of Windows 7 are distributed on two DVDs: one for the IA-32 version and the other for x86-64. OEM copies include one DVD, depending on the processor architecture licensed. The installation media for consumer versions of Windows 7 are identical, the product key and corresponding license determines the edition that is installed. The Windows Anytime Upgrade service can be used to purchase an upgrade that unlocks the functionality of a higher edition, such as going from Starter to Home Premium, and Home Premium to Ultimate. Most copies of Windows 7 only contained one license; in certain markets, a "Family Pack" version of Windows 7 Home Premium was also released for a limited time, which allowed upgrades on up to three computers. In certain regions, copies of Windows 7 were only sold in, and could only be activated in a designated region. Support lifecycle Support for Windows 7 without Service Pack 1 ended on April 9, 2013, requiring users to update in order to continue receiving updates and support after 3 years, 8 months, and 18 days. Microsoft ended the sale of new retail copies of Windows 7 in October 2014, and the sale of new OEM licenses for Windows 7 Home Basic, Home Premium, and Ultimate ended on October 31, 2014. OEM sales of PCs with Windows 7 Professional pre-installed ended on October 31, 2016. The sale of non-Professional OEM licenses was stopped on October 31, 2014. Support for Windows Vista ended on April 11, 2017, requiring users to upgrade in order to continue receiving updates and support. Mainstream support for Windows 7 ended on January 13, 2015. Extended support for Windows 7 ended on January 14, 2020. In August 2019, Microsoft announced it will be offering a 'free' extended security updates to some business users. On September 7, 2018, Microsoft announced a paid "Extended Security Updates" service that will offer additional updates for Windows 7 Professional and Enterprise for up to three years after the end of extended support. Variants of Windows 7 for embedded systems and thin clients have different support policies: Windows Embedded Standard 7 support ended in October 2020. Windows Thin PC and Windows Embedded POSReady 7 had support until October 2021. Windows Embedded Standard 7 and Windows Embedded POSReady 7 also get Extended Security Updates for up to three years after their end of extended support date. However, these embedded edition updates aren't able to be downloaded on non-embedded Windows 7 editions with a simple registry hack, unlike Windows XP with its embedded editions updates. Instead, a more complex patching tool, that allows the installation of pirated Extended Security Updates, ended up being the only solution to allow consumer variants to continue to receive updates. The Extended Security Updates service on Windows Embedded POSReady 7 will expire on October 14, 2024. This will mark the final end of the Windows NT 6.1 product line after 15 years, 2 months, and 17 days. In March 2019, Microsoft announced that it would display notifications to users informing users of the upcoming end of support, and direct users to a website urging them to purchase a Windows 10 upgrade or a new computer. In August 2019, researchers reported that "all modern versions of Microsoft Windows" may be at risk for "critical" system compromise because of design flaws of hardware device drivers from multiple providers. In the same month, computer experts reported that the BlueKeep security vulnerability, , that potentially affects older unpatched Microsoft Windows versions via the program's Remote Desktop Protocol, allowing for the possibility of remote code execution, may now include related flaws, collectively named DejaBlue, affecting newer Windows versions (i.e., Windows 7 and all recent versions) as well. In addition, experts reported a Microsoft security vulnerability, , based on legacy code involving Microsoft CTF and ctfmon (ctfmon.exe), that affects all Windows versions from the older Windows XP version to the most recent Windows 10 versions; a patch to correct the flaw is currently available. As of January 15, 2020, Windows Update is blocked from running on Windows 7. In September 2019, Microsoft announced that it would provide free security updates for Windows 7 on federally-certified voting machines through the 2020 United States elections. System requirements Additional requirements to use certain features: Windows XP Mode (Professional, Ultimate and Enterprise): Requires an additional 1 GB of RAM and additional 15 GB of available hard disk space. The requirement for a processor capable of hardware virtualization has been lifted. Windows Media Center (included in Home Premium, Professional, Ultimate and Enterprise), requires a TV tuner to receive and record TV. Extent of hardware support Physical memory The maximum amount of RAM that Windows 7 supports varies depending on the product edition and on the processor architecture, as shown in the following table. Processor limits Windows 7 Professional and up support up to 2 physical processors (CPU sockets), whereas Windows 7 Starter, Home Basic, and Home Premium editions support only 1. Physical processors with either multiple cores, or hyper-threading, or both, implement more than one logical processor per physical processor. The x86 editions of Windows 7 support up to 32 logical processors; x64 editions support up to 256 (4 x 64). In January 2016, Microsoft announced that it would no longer support Windows platforms older than Windows 10 on any future Intel-compatible processor lines, citing difficulties in reliably allowing the operating system to operate on newer hardware. Microsoft stated that effective July 17, 2017, devices with Intel Skylake CPUs were only to receive the "most critical" updates for Windows 7 and 8.1, and only if they have been judged not to affect the reliability of Windows 7 on older hardware. For enterprise customers, Microsoft issued a list of Skylake-based devices "certified" for Windows 7 and 8.1 in addition to Windows 10, to assist them in migrating to newer hardware that can eventually be upgraded to 10 once they are ready to transition. Microsoft and their hardware partners provide special testing and support for these devices on 7 and 8.1 until the July 2017 date. On March 18, 2016, in response to criticism from enterprise customers, Microsoft delayed the end of support and non-critical updates for Skylake systems to July 17, 2018, but stated that they would also continue to receive security updates through the end of extended support. In August 2016, citing a "strong partnership with our OEM partners and Intel", Microsoft retracted the decision and stated that it would continue to support Windows 7 and 8.1 on Skylake hardware through the end of their extended support lifecycle. However, the restrictions on newer CPU microarchitectures remain in force. In March 2017, a Microsoft knowledge base article announced which implies that devices using Intel Kaby Lake, AMD Bristol Ridge, or AMD Ryzen, would be blocked from using Windows Update entirely. In addition, official Windows 7 device drivers are not available for the Kaby Lake and Ryzen platforms. Security updates released since March 2018 contain bugs which affect processors that do not support SSE2 extensions, including all Pentium III processors. Microsoft initially stated that it would attempt to resolve the issue, and prevented installation of the affected patches on these systems. However, on June 15, 2018, Microsoft retroactively modified its support documents to remove the promise that this bug would be resolved, replacing it with a statement suggesting that users obtain a newer processor. This effectively ends future patch support for Windows 7 on these systems. Updates Service Pack 1 Windows 7 Service Pack 1 (SP1) was announced on March 18, 2010. A beta was released on July 12, 2010. The final version was released to the public on February 22, 2011. At the time of release, it was not made mandatory. It was available via Windows Update, direct download, or by ordering the Windows 7 SP1 DVD. The service pack is on a much smaller scale than those released for previous versions of Windows, particularly Windows Vista. Windows 7 Service Pack 1 adds support for Advanced Vector Extensions (AVX), a 256-bit instruction set extension for processors, and improves IKEv2 by adding additional identification fields such as E-mail ID to it. In addition, it adds support for Advanced Format 512e as well as additional Identity Federation Services. Windows 7 Service Pack 1 also resolves a bug related to HDMI audio and another related to printing XPS documents. In Europe, the automatic nature of the BrowserChoice.eu feature was dropped in Windows 7 Service Pack 1 in February 2011 and remained absent for 14 months despite Microsoft reporting that it was still present, subsequently described by Microsoft as a "technical error." As a result, in March 2013, the European Commission fined Microsoft €561 million to deter companies from reneging on settlement promises. Platform Update The Platform Update for Windows 7 SP1 and Windows Server 2008 R2 SP1 was released on February 26, 2013 after a pre-release version had been released on November 5, 2012. It is also included with Internet Explorer 10 for Windows 7. It includes enhancements to Direct2D, DirectWrite, Direct3D, Windows Imaging Component (WIC), Windows Advanced Rasterization Platform (WARP), Windows Animation Manager (WAM), XPS Document API, H.264 Video Decoder and JPEG XR decoder. However support for Direct3D 11.1 is limited as the update does not include DXGI/WDDM 1.2 from Windows 8, making unavailable many related APIs and significant features such as stereoscopic frame buffer, feature level 11_1 and optional features for levels 10_0, 10_1 and 11_0. Disk Cleanup update In October 2013, a Disk Cleanup Wizard addon was released that lets users delete outdated Windows updates on Windows 7 SP1, thus reducing the size of the WinSxS directory. This update backports some features found in Windows 8. Windows Management Framework 5.0 Windows Management Framework 5.0 includes updates to Windows PowerShell 5.0, Windows PowerShell Desired State Configuration (DSC), Windows Remote Management (WinRM), Windows Management Instrumentation (WMI). It was released on February 24, 2016 and was eventually superseded by Windows Management Framework 5.1. Convenience rollup In May 2016, Microsoft released a "Convenience rollup update for Windows 7 SP1 and Windows Server 2008 R2 SP1," which contains all patches released between the release of SP1 and April 2016. The rollup is not available via Windows Update, and must be downloaded manually. This package can also be integrated into a Windows 7 installation image. Since October 2016, all security and reliability updates are cumulative. Downloading and installing updates that address individual problems is no longer possible, but the number of updates that must be downloaded to fully update the OS is significantly reduced. Monthly update rollups (July 2016-January 2020) In June 2018, Microsoft announced that they'll be moving Windows 7 to a monthly update model beginning with updates released in September 2018 - two years after Microsoft switched the rest of their supported operating systems to that model. With the new update model, instead of updates being released as they became available, only two update packages were released on the second Tuesday of every month until Windows 7 reached its end of life - one package containing security and quality updates, and a smaller package that contained only the security updates. Users could choose which package they wanted to install each month. Later in the month, another package would be released which was a preview of the next month's security and quality update rollup. Installing the preview rollup package released for Windows 7 on March 19, 2019, or any later released rollup package, that makes Windows more reliable. This change was made so Microsoft could continue to service the operating system while avoiding “version-related issues”. Microsoft announced in July 2019 that the Microsoft Internet Games services on Windows XP and Windows Me would end on July 31, 2019 (and for Windows 7 on January 22, 2020). The last non-extended security update rollup packages were released on January 14, 2020, the last day that Windows 7 had extended support. End of support (after January 14, 2020) On January 14, 2020, Windows 7 support ended with Microsoft no longer providing security updates or fixes after that date, except for subscribers of the Windows 7 Extended Security Updates. However, there have been two updates that have been issued to non-ESU subscribers: In February 2020, Microsoft released an update via Windows Update to fix a black wallpaper issue caused by the January 2020 update for Windows 7. In June 2020, Microsoft released an update via Windows Update to roll out the new Chromium-based Microsoft Edge to Windows 7 and 8.1 machines that are not connected to Active Directory. Users, e.g. those on Active Directory, can download Edge from Microsoft's website. In a support document, Microsoft has stated that a full-screen upgrade warning notification would be displayed on Windows 7 PCs on all editions except the Enterprise edition after January 15. The notification does not appear on machines connected to Active Directory, machines in kiosk mode, or machines subscribed for Extended Security Updates. Reception Critical reception Windows 7 received critical acclaim, with critics noting the increased usability and functionality when compared with its predecessor, Windows Vista. CNET gave Windows 7 Home Premium a rating of 4.5 out of 5 stars, stating that it "is more than what Vista should have been, [and] it's where Microsoft needed to go". PC Magazine rated it a 4 out of 5 saying that Windows 7 is a "big improvement" over Windows Vista, with fewer compatibility problems, a retooled taskbar, simpler home networking and faster start-up. Maximum PC gave Windows 7 a rating of 9 out of 10 and called Windows 7 a "massive leap forward" in usability and security, and praised the new Taskbar as "worth the price of admission alone." PC World called Windows 7 a "worthy successor" to Windows XP and said that speed benchmarks showed Windows 7 to be slightly faster than Windows Vista. PC World also named Windows 7 one of the best products of the year. In its review of Windows 7, Engadget said that Microsoft had taken a "strong step forward" with Windows 7 and reported that speed is one of Windows 7's major selling points—particularly for the netbook sets. Laptop Magazine gave Windows 7 a rating of 4 out of 5 stars and said that Windows 7 makes computing more intuitive, offered better overall performance including a "modest to dramatic" increase in battery life on laptop computers. TechRadar gave Windows 7 a rating of 5 out of 5 stars, concluding that "it combines the security and architectural improvements of Windows Vista with better performance than XP can deliver on today's hardware. No version of Windows is ever perfect, but Windows 7 really is the best release of Windows yet." USA Today and The Telegraph also gave Windows 7 favorable reviews. Nick Wingfield of The Wall Street Journal wrote, "Visually arresting," and "A pleasure." Mary Branscombe of Financial Times wrote, "A clear leap forward." of Gizmodo wrote, "Windows 7 Kills Snow Leopard." Don Reisinger of CNET wrote, "Delightful." David Pogue of The New York Times wrote, "Faster." J. Peter Bruzzese and Richi Jennings of Computerworld wrote, "Ready." Some Windows Vista Ultimate users have expressed concerns over Windows 7 pricing and upgrade options. Windows Vista Ultimate users wanting to upgrade from Windows Vista to Windows 7 had to either pay $219.99 to upgrade to Windows 7 Ultimate or perform a clean install, which requires them to reinstall all of their programs. The changes to User Account Control on Windows 7 were criticized for being potentially insecure, as an exploit was discovered allowing untrusted software to be launched with elevated privileges by exploiting a trusted component. Peter Bright of Ars Technica argued that "the way that the Windows 7 UAC 'improvements' have been made completely exempts Microsoft's developers from having to do that work themselves. With Windows 7, it's one rule for Redmond, another one for everyone else." Microsoft's Windows kernel engineer Mark Russinovich acknowledged the problem, but noted that malware can also compromise a system when users agree to a prompt. Sales In July 2009, in only eight hours, pre-orders of Windows 7 at amazon.co.uk surpassed the demand which Windows Vista had in its first 17 weeks. It became the highest-grossing pre-order in Amazon's history, surpassing sales of the previous record holder, the seventh Harry Potter book. After 36 hours, 64-bit versions of Windows 7 Professional and Ultimate editions sold out in Japan. Two weeks after its release its market share had surpassed that of Snow Leopard, released two months previously as the most recent update to Apple's Mac OS X operating system. According to Net Applications, Windows 7 reached a 4% market share in less than three weeks; in comparison, it took Windows Vista seven months to reach the same mark. As of February 2014, Windows 7 had a market share of 47.49% according to Net Applications; in comparison, Windows XP had a market share of 29.23%. On March 4, 2010, Microsoft announced that it had sold more than 90 million licenses. By April 23, 2010, more than 100 million copies were sold in six months, which made it Microsoft's fastest-selling operating system. As of June 23, 2010, Windows 7 has sold 150 million copies which made it the fastest selling operating system in history with seven copies sold every second. Based on worldwide data taken during June 2010 from Windows Update 46% of Windows 7 PCs run the 64-bit edition of Windows 7. According to Stephen Baker of the NPD Group during April 2010 in the United States 77% of PCs sold at retail were pre-installed with the 64-bit edition of Windows 7. As of July 22, 2010, Windows 7 had sold 175 million copies. On October 21, 2010, Microsoft announced that more than 240 million copies of Windows 7 had been sold. Three months later, on January 27, 2011, Microsoft announced total sales of 300 million copies of Windows 7. On July 12, 2011, the sales figure was refined to over 400 million end-user licenses and business installations. As of July 9, 2012, over 630 million licenses have been sold; this number includes licenses sold to OEMs for new PCs. Antitrust concerns As with other Microsoft operating systems, Windows 7 was studied by United States federal regulators who oversee the company's operations following the 2001 United States v. Microsoft Corp. settlement. According to status reports filed, the three-member panel began assessing prototypes of the new operating system in February 2008. Michael Gartenberg, an analyst at Jupiter Research, said, "[Microsoft's] challenge for Windows 7 will be how can they continue to add features that consumers will want that also don't run afoul of regulators." In order to comply with European antitrust regulations, Microsoft proposed the use of a "ballot" screen containing download links to competing web browsers, thus removing the need for a version of Windows completely without Internet Explorer, as previously planned. Microsoft announced that it would discard the separate version for Europe and ship the standard upgrade and full packages worldwide, in response to criticism involving Windows 7 E and concerns from manufacturers about possible consumer confusion if a version of Windows 7 with Internet Explorer were shipped later, after one without Internet Explorer. As with the previous version of Windows, an N version, which does not come with Windows Media Player, has been released in Europe, but only for sale directly from Microsoft sales websites and selected others. See also BlueKeep, a security vulnerability discovered in May 2019 that affected most Windows NT-based computers up to Windows 7 References Further reading External links Windows 7 Service Pack 1 (SP1) Windows 7 SP1 update history 2009 software IA-32 operating systems 7 X86-64 operating systems

Operating System (OS)

OS X El Capitan OS X El Capitan ( ) () is the twelfth major release of macOS (named OS X at the time of El Capitan's release), Apple Inc.'s desktop and server operating system for Macintosh. It focuses mainly on performance, stability, and security. Following the Northern California landmark-based naming scheme introduced with OS X Mavericks, El Capitan was named after a rock formation in Yosemite National Park. El Capitan is the final version to be released under the name OS X. OS X El Capitan received far better reviews than did Yosemite. The first beta of OS X El Capitan was released to developers shortly following the WWDC keynote on June 8, 2015. The first public beta was made available on July 9, 2015. There were multiple betas released after the keynote. OS X El Capitan was released to end users on September 30, 2015, as a free upgrade through the Mac App Store. System requirements All Macintosh computers that can run Mountain Lion, Mavericks, or Yosemite can run El Capitan, although not all of its features will work on older computers. For example, Apple notes that the newly available Metal API is available on "all Macs since 2012". These computers can run El Capitan, provided they have at least 2GB of RAM: MacBook: Late 2008 or newer MacBook Air: Late 2008 or newer MacBook Pro: Mid 2007 or newer Mac Mini: Early 2009 or newer iMac: Mid 2007 or newer Mac Pro: Early 2008 or newer Xserve: Early 2009 Of these computers, the following models were equipped with 1GB RAM as the standard option on the base model when they were shipped originally. They can only run OS X El Capitan if they have at least 2GB of RAM. iMac: Mid 2007 - Early 2008 Mac Mini: Early 2009 The following computers support features such as Handoff, Instant Hotspot, AirDrop between Mac computers and iOS devices, as well as the new Metal API: iMac: Late 2012 or newer MacBook: Early 2015 or newer MacBook Air: Mid 2012 or newer MacBook Pro: Mid 2012 or newer Mac Mini: Late 2012 or newer Mac Pro: Late 2013 The upgrade varies in size depending upon which Apple Mac computer it is being installed on; in most scenarios, it will require about 6 GB of disk space. Features OS X El Capitan includes features to improve the security, performance, design and usability of OS X. Compared to OS X Yosemite, Apple says that opening PDFs is four times faster, app switching and viewing messages in Mail is twice as fast and launching apps is 40% faster. The maximum amount of memory that could be allocated to the graphics processor has been increased from 1024 MB to 1536 MB on Macs with an Intel HD 4000 GPU. OS X El Capitan supports Metal, Apple's graphics API introduced in iOS 8 to speed up performance in games and professional applications. Apple's typeface San Francisco replaces Helvetica Neue as the system typeface. OS X El Capitan also adopts LibreSSL in replacement of OpenSSL used in previous versions. Window management OS X El Capitan introduces new window management features such as creating a full-screen split screen limited to two app windows side by side in full screen by pressing the green button on left upper corner of the window or Control+Cmd+F keyboard shortcut, then snapping any supported other window to that full screen application. This feature is slightly similar to, although less extensive than, the snap-assist feature in Windows 7 (and later) and several Linux desktop environments, such as GNOME. OS X El Capitan improves Mission Control to incorporate this feature across multiple spaces. It also enables users to spot the pointer more easily by enlarging it by shaking the mouse or swiping a finger back and forth on the trackpad. Applications Messages and Mail OS X El Capitan adds multi-touch gestures to applications like Mail and Messages that allow a user to delete or mark emails or conversations by swiping a finger on a multi-touch device, such as a trackpad. OS X also analyzes the contents of individual emails in Mail and uses the gathered information in other applications, such as Calendar. For example, an invitation in Mail can automatically be added as a Calendar event. Maps Apple Maps in El Capitan shows public transit information similar to Maps in iOS 9. This feature was limited to a handful of cities upon launch: Baltimore, Berlin, Chicago, London, Los Angeles, Mexico City, New York City, Paris, Philadelphia, San Francisco, Shanghai, Toronto and Washington D.C. Notes The Notes application receives an overhaul, similar to Notes in iOS 9. Both applications have more powerful text-processing capabilities, such as to-do lists (like in the Reminders application), inline webpage previews, photos and videos, digital sketches, map locations and other documents and media types. Notes replaces traditional IMAP-based syncing with iCloud, which offers better end-to-end encryption and faster syncing. Safari Safari in El Capitan lets users pin tabs for frequently accessed websites to the tab bar, similar to Firefox and Google Chrome. Users are able to quickly identify and mute tabs that play audio without having to search for individual tabs. Safari supports AirPlay video streaming to an Apple TV without the need to broadcast the entire webpage. Safari extensions are now hosted and signed by Apple as part of the updated Apple Developer program and they received native support for content blocking, allowing developers to block website components (such as advertisements) without JavaScript injection. The app also allows the user to customize the font and background of the Reader mode. Spotlight Spotlight is improved with more contextual information such as the weather, stocks, news and sports scores. It is also able to process queries in natural language. For example, users can type "Show me pictures that I took in Yosemite National Park in July 2014" and Spotlight will use that request to bring up the corresponding info. The app can now be resized and moved across the screen. Photos Photos introduced editing extensions, which allow Photos to use editing tools from other apps. Other applications found in OS X 10.11 El Capitan AirPort Utility App Store Archive Utility Audio MIDI Setup Automator Bluetooth File Exchange Boot Camp Assistant Calculator Calendar Chess ColorSync Utility) Console Contacts Dictionary Digital Color Meter Disk Utility DVD Player FaceTime Font Book Game Center GarageBand (may not be pre-installed) Grab Grapher iBooks (now Apple Books) iMovie (may not be pre-installed) iTunes Image Capture Ink (can only be accessed by connecting a graphics tablet to your Mac) Keychain Access Keynote (may not be pre-installed) Migration Assistant Numbers (may not be pre-installed) Pages (may not be pre-installed) Photo Booth Preview QuickTime Player Reminders Script Editor Stickies System Information Terminal TextEdit Time Machine VoiceOver Utility X11/XQuartz (may not be pre-installed) System Integrity Protection OS X El Capitan has a new security feature called System Integrity Protection (SIP, sometimes referred to as "rootless") that protects certain system processes, files and folders from being modified or tampered with by other processes even when executed by the root user or by a user with root privileges (sudo). Apple says that the root user can be a significant risk factor to the system's security, especially on systems with a single user account on which that user is also the administrator. System Integrity Protection is enabled by default, but can be disabled. Reception Upon release, OS X El Capitan was met with positive reception from both users and critics, with praise mostly going towards the overall functionality of the new features and improved stability. Dieter Bohn of The Verge awarded the operating system a score of 8.5 out of 10; while Jason Snell of Macworld was also positive, rating it 4.5 out of 5. Many people criticized Apple's native apps for not having improved beyond third-party applications. Issues After the 10.11.4 update, many users started reporting that their MacBooks were freezing, requiring a hard reboot. This issue mostly affects Early 2015 MacBook Pro computers, although many others have reported freezes in other models. Several users created videos on YouTube which showed the freezes. Soon after this, Apple released the 10.11.5 update, which contained stability improvements. Apple later acknowledged these problems, recommending their users to update to the last point release. After the December 13, 2016, release of Security Update 2016–003, users reported problems with the WindowServer process becoming unresponsive, causing the GUI to freeze and sometimes necessitating a hard reboot to fix. In response, on January 17, 2017, Apple released Security Update 2016-003 Supplemental (10.11.6) to fix "a kernel issue that may cause your Mac to occasionally become unresponsive" and at the same time released an updated version of Security Update 2016-003 which includes the fix released in the supplemental. Users who have not previously installed Security Update 2016-003 are advised to install the updated version to reach build 15G1217, while users who have already installed the December 13, 2016 Security Update 2016-003 only need to install the supplemental update. Release history References External links – official site OS X El Capitan download page at Apple 11 X86-64 operating systems 2015 software Computer-related introductions in 2015

Operating System (OS)

Whitix Whitix is a desktop computer operating system written from scratch for the x86 architecture by Matthew Whitworth and others. The project aims to combine proven system technology (a Unix-like kernel), while "offering a consistent and clear interface and a new way to navigate the desktop." The operating system runs on a custom open source kernel written by Whitworth; new features include IcFs, a dynamic configuration filesystem that replaces ioctl. The modular kernel of Whitix is licensed under the GNU General Public License, and is a fully preemptive multitasking kernel with multithreading. It supports a number of filesystems, including the FAT family of filesystems, ext3 (with journaling), Reiserfs and ISO9660. Whitix is available as a live CD for download, and can be installed to the hard drive, beginning with version 0.2. The userspace comprises a native shell, Burn, and text editor, Fruity, and a range of ported applications. A C-based and BSD-licensed software development kit is available, with bindings for various languages. Whitix contains a POSIX compatibility library (libposix), but does not aim for full POSIX compliance. Whitix's windowing environment is Xynth, a lightweight windowing environment developed by Alper Akcan. Software The custom userspace software for Whitix consists of a range of third party applications, Burn (a non-POSIX shell), Fruity (a simple text editor) and several filesystem utilities. Software ported to Whitix includes the Mono runtime environment and C# compiler, Python, the GNU Compiler Collection, Lua, mplayer and other ports. The operating system has been self-hosting since October 2008, when it was built with the GNU build chain. For 0.3, a port of GTK and several Linux applications is planned. Whitix also adopts a centralized approach to userland configuration, similar to the Windows registry. Although not widely used by Whitix software at the moment, it includes settings for the operating system's software. It will also be linked into the Whitix package management system, which is currently in development. Programming on Whitix Whitix supports several programming languages, using utilities ported from other operating systems. The most common collection of utilities for building both Whitix applications and operating system programs is found within the GNU toolchain, which includes the GNU Compiler Collection (GCC) and the GNU Build System. Amongst others, GCC provides compilers for Ada, C, C++ and Fortran. The Whitix kernel itself is designed to be built with GCC. Ports for languages such as Python, Lua and other dynamic languages are available as ports. The .NET languages are also supported, as Mono has been ported to the platform. Applications in the planned Blaze platform will be built with managed code. Releases The development team issue releases "when it's ready". However, no versions of Whitix have been declared stable for general use. The latest release is 0.2b, which was released on 1 March 2009. The timing of each release depends on the stability of features planned to be included, although a monthly release pattern of minor versions and improvements is an aim for the developers at Whitix.org. Notes and references External links Free software operating systems Unix variants

Operating System (OS)

System Information (Windows) System Information (msinfo32.exe) is a system profiler included with Microsoft Windows that displays diagnostic and troubleshooting information related to the operating system, hardware and software. It has been bundled with Windows since Windows NT 4.0. It compiles technical information on the overall system, hardware resources (including memory, I/O, etc.), physical hardware components (CD-ROM, sound, network, etc.), and the Windows environment as well (drivers, environment variables, services, etc.). It can export this information in the plain text format or in files with a .nfo extension, which can be used to diagnose problems. In addition, System Information can be used to gather technical information on a remote computer on the same network. See also Systeminfo.exe MSConfig References Windows components

Operating System (OS)

System virtual machine In computing, a system virtual machine is a virtual machine that provides a complete system platform and supports the execution of a complete operating system (OS). These usually emulate an existing architecture, and are built with the purpose of either providing a platform to run programs where the real hardware is not available for use (for example, executing on otherwise obsolete platforms), or of having multiple instances of virtual machines leading to more efficient use of computing resources, both in terms of energy consumption and cost effectiveness (known as hardware virtualization, the key to a cloud computing environment), or both. A VM was originally defined by Popek and Goldberg as "an efficient, isolated duplicate of a real machine". System virtual machines System virtual machine advantages: Multiple OS environments can co-exist on the same primary hard drive, with a virtual partition that allows sharing of files generated in either the "host" operating system or "guest" virtual environment. Adjunct software installations, wireless connectivity, and remote replication, such as printing and faxing, can be generated in any of the guest or host operating systems. Regardless of the system, all files are stored on the hard drive of the host OS. Application provisioning, maintenance, high availability and disaster recovery are inherent in the virtual machine software selected. Can provide emulated hardware environments different from the host's instruction set architecture (ISA), through emulation or by using just-in-time compilation. The main disadvantages of VMs are: A virtual machine is less efficient than an actual machine when it accesses the host hard drive indirectly. When multiple VMs are concurrently running on the hard drive of the actual host, adjunct virtual machines may exhibit a varying and/or unstable performance (speed of execution and malware protection). This depends on the data load imposed on the system by other VMs, unless the selected VM software provides temporal isolation among virtual machines. Malware protections for VMs are not necessarily compatible with the "host", and may require separate software. Multiple VMs running their own guest operating system are frequently engaged for server consolidation in order to avoid interference from separate VMs on the same actual machine platform. The desire to run multiple operating systems was the initial motivation for virtual machines, so as to allow time-sharing among several single-tasking operating systems. In some respects, a system virtual machine can be considered a generalization of the concept of virtual memory that historically preceded it. IBM's CP/CMS, the first systems to allow full virtualization, implemented time sharing by providing each user with a single-user operating system, the CMS. Unlike virtual memory, a system virtual machine entitled the user to write privileged instructions in their code. This approach had certain advantages, such as adding input/output devices not allowed by the standard system. As technology evolves virtual memory for purposes of virtualization, new systems of memory overcommitment may be applied to manage memory sharing among multiple virtual machines on one actual computer operating system. It may be possible to share "memory pages" that have identical contents among multiple virtual machines that run on the same physical machine, what may result in mapping them to the same physical page by a technique known as Kernel SamePage Merging. This is particularly useful for read-only pages, such as those that contain code segments; in particular, that would be the case for multiple virtual machines running the same or similar software, software libraries, web servers, middleware components, etc. The guest operating systems do not need to be compliant with the host hardware, thereby making it possible to run different operating systems on the same computer (e.g., Microsoft Windows, Linux, or previous versions of an operating system) to support future software. The use of virtual machines to support separate guest operating systems is popular in regard to embedded systems. A typical use would be to run a real-time operating system simultaneously with a preferred complex operating system, such as Linux or Windows. Another use would be for novel and unproven software still in the developmental stage, so it runs inside a sandbox. Virtual machines have other advantages for operating system development, and may include improved debugging access and faster reboots. Techniques Different virtualization techniques are used, based on the desired usage. Native execution is based on direct virtualization of the underlying raw hardware, thus it provides multiple "instances" of the same architecture a real machine is based on, capable of running complete operating systems. Some virtual machines can also emulate different architectures and allow execution of software applications and operating systems written for another CPU or architecture. Operating-system-level virtualization allows the resources of a computer to be partitioned via kernel's support for multiple isolated user space instances, which are usually called containers and may look and feel like real machines to the end users. Some computer architectures are capable of hardware-assisted virtualization, which enables efficient full virtualization by using virtualization-specific hardware capabilities, primarily from the host CPUs. Virtualization of the underlying raw hardware (native execution) This approach is described as full virtualization of the hardware, and can be implemented using a type 1 or type 2 hypervisor: a type 1 hypervisor runs directly on the hardware, and a type 2 hypervisor runs on another operating system, such as Linux or Windows. Each virtual machine can run any operating system supported by the underlying hardware. Users can thus run two or more different "guest" operating systems simultaneously, in separate "private" virtual computers. The pioneer system using this concept was IBM's CP-40, the first (1967) version of IBM's CP/CMS (1967–1972) and the precursor to IBM's VM family (1972–present). With the VM architecture, most users run a relatively simple interactive computing single-user operating system, CMS, as a "guest" on top of the VM control program (VM-CP). This approach kept the CMS design simple, as if it were running alone; the control program quietly provides multitasking and resource management services "behind the scenes". In addition to CMS communication and other system tasks are performed by multitasking VMs (RSCS, GCS, TCP/IP, UNIX), and users can run any of the other IBM operating systems, such as MVS, even a new CP itself or now z/OS. Even the simple CMS could be run in a threaded environment (LISTSERV, TRICKLE). z/VM is the current version of VM, and is used to support hundreds or thousands of virtual machines on a given mainframe. Some installations use Linux on IBM Z to run Web servers, where Linux runs as the operating system within many virtual machines. Full virtualization is particularly helpful in operating system development, when experimental new code can be run at the same time as older, more stable, versions, each in a separate virtual machine. The process can even be recursive: IBM debugged new versions of its virtual machine operating system, VM, in a virtual machine running under an older version of VM, and even used this technique to simulate new hardware. The standard x86 instruction set architecture as used in the modern PCs does not actually meet the Popek and Goldberg virtualization requirements. Notably, there is no execution mode where all sensitive machine instructions always trap, which would allow per-instruction virtualization. Despite these limitations, several software packages have managed to provide virtualization on the x86 architecture, even though dynamic recompilation of privileged code, as first implemented by VMware, incurs some performance overhead as compared to a VM running on a natively virtualizable architecture such as the IBM System/370 or Motorola MC68020. By now, several other software packages such as Virtual PC, VirtualBox, Parallels Workstation and Virtual Iron manage to implement virtualization on x86 hardware. Intel and AMD have introduced features to their x86 processors to enable virtualization in hardware. As well as virtualization of the resources of a single machine, multiple independent nodes in a cluster can be combined and accessed as a single virtual NUMA machine. Emulation of a non-native system Virtual machines can also perform the role of an emulator, allowing software applications and operating systems written for another computer processor architecture to be run. Operating-system-level virtualization Operating-system-level virtualization is a server virtualization technology which virtualizes servers on an operating system (kernel) layer. It can be thought of as partitioning: a single physical server is sliced into multiple small partitions (otherwise called virtual environments (VE), virtual private servers (VPS), guests, zones, etc.); each such partition looks and feels like a real server, from the point of view of its users. For example, Solaris Zones supports multiple guest operating systems running under the same operating system such as Solaris 10. Guest operating systems can use the same kernel level with the same operating system version, or can be a separate copy of the operating system with a different kernel version using Solaris Kernel Zones. Solaris native Zones also requires that the host operating system is a version of Solaris; other operating systems from other manufacturers are not supported. However, Solaris Branded Zones would need to be used to have other operating systems as zones. Another example is System Workload Partitions (WPARs), introduced in version 6.1 of the IBM AIX operating system. System WPARs are software partitions running under one instance of the global AIX OS environment. The operating system level architecture has low overhead that helps to maximize efficient use of server resources. The virtualization introduces only a negligible overhead and allows running hundreds of virtual private servers on a single physical server. In contrast, approaches such as full virtualization (like VMware) and paravirtualization (like Xen or UML) cannot achieve such level of density, due to overhead of running multiple kernels. From the other side, operating system-level virtualization does not allow running different operating systems (i.e., different kernels), although different libraries, distributions, etc. are possible. Different virtualization techniques are used, based on the desired usage. Native execution is based on direct virtualization of the underlying raw hardware, thus it provides multiple "instances" of the same architecture a real machine is based on, capable of running complete operating systems. Some virtual machines can also emulate different architectures and allow execution of software applications and operating systems written for another CPU or architecture. Operating-system-level virtualization allows the resources of a computer to be partitioned via kernel's support for multiple isolated user space instances, which are usually called containers and may look and feel like real machines to the end users. Some computer architectures are capable of hardware-assisted virtualization, which enables efficient full virtualization by using virtualization-specific hardware capabilities, primarily from the host CPUs. Virtualization-enabled hardware Examples of virtualization-enabled hardware include the following: Alcatel-Lucent 3B20D/3B21D emulated on commercial off-the-shelf computers with 3B2OE or 3B21E system ARM TrustZone Boston Circuits gCore (grid-on-chip) with 16 ARC 750D cores and Time-machine hardware virtualization module. Freescale PowerPC MPC8572 and MPC8641D IBM System/360 Model 67, System/370, System/390, and zSeries mainframes IBM Power Systems x86: AMD-V (formerly code-named Pacifica) Intel VT-x (formerly code-named Vanderpool) HP vPAR and cell based nPAR GE and Honeywell Multics systems Honeywell 200/2000 systems Liberator replacing IBM 14xx systems Honeywell Level 62/64/66 IBM System/360 and System/370 models with emulators supporting programs for older IBM systems Honeywell Level 6 minicomputers emulated predecessor 316/516/716 minis Oracle Corporation (previously Sun Microsystems) SPARC sun4v (SPARC M6, T5, T4, T3, UltraSPARC T1 and T2) utilized by Oracle VM Server for SPARC, also known as "Logical Domains" Xerox Sigma 6 CPUs were modified to emulate GE/Honeywell 600/6000 systems See also Amazon Machine Image Linux containers Storage hypervisor Universal Turing machine Virtual appliance Virtual backup appliance Virtual disk image Virtual machine escape Notes References Further reading James E. Smith, Ravi Nair, Virtual Machines: Versatile Platforms For Systems And Processes, Morgan Kaufmann, May 2005, , 656 pages (covers both process and system virtual machines) Craig, Iain D. Virtual Machines. Springer, 2006, , 269 pages (covers only process virtual machines) External links The Reincarnation of Virtual Machines, Article on ACM Queue by Mendel Rosenblum, Co-Founder, VMware Operating system technology

Operating System (OS)

Mac OS 8 Mac OS 8 is an operating system that was released by Apple Computer, Inc. on July 26, 1997. It includes the largest overhaul of the classic Mac OS experience since the release of System 7, approximately six years before. It places a greater emphasis on color than prior versions. Released over a series of updates, Mac OS 8 represents an incremental integration of many of the technologies which had been developed from 1988 to 1996 for Apple's overly ambitious OS named Copland. Mac OS 8 helped modernize the Mac OS while Apple developed its next-generation operating system, Mac OS X (renamed in 2012 to OS X and then in 2016 to macOS). Mac OS 8 is one of Apple's most commercially successful software releases, selling over 1.2 million copies in the first two weeks. As it came at a difficult time in Apple's history, many pirate groups refused to traffic in the new OS, encouraging people to buy it instead. Mac OS 8.0 introduces the most visible changes in the lineup, including the Platinum interface and a native PowerPC multithreaded Finder. Mac OS 8.1 introduces a new, more efficient file system named HFS Plus. Mac OS 8.5 is the first version of the Mac OS to require a PowerPC processor. It features PowerPC native versions of QuickDraw, AppleScript, and the Sherlock search utility. Its successor, Mac OS 9, was released on October 23, 1999. Copland Starting in 1988, Apple's next-generation operating system, which it originally envisioned to be "System 8" was codenamed Copland. It was announced in March 1994 alongside the introduction of the first PowerPC Macs. Apple intended Copland as a fully modern system, including native PowerPC code, intelligent agents, a microkernel, a customizable interface named Appearance Manager, a hardware abstraction layer, and a relational database integrated into the Finder. Copland was to be followed by Gershwin, which promised memory protection spaces and full preemptive multitasking. The system was intended to be a full rewrite of the Mac OS, and Apple hoped to beat Microsoft Windows 95 to market with a development cycle of only one year. The Copland development was hampered by many missed deadlines. The release date was first pushed back to the end of 1995, then to mid-1996, late 1996, and finally to the end of 1997. With a dedicated team of 500 software engineers and an annual budget of $250 million, Apple executives began to grow impatient with the project continually falling behind schedule. At the Worldwide Developers Conference in January 1997, Apple chief executive officer (CEO) Gil Amelio announced that, rather than release Copland as one monolithic release, Copland features would be phased into the Mac OS following a six-month release cycle. These updates began with Mac OS 7.6, released during WWDC. Mac OS 8.0, released six months later, continued to integrate Copland technologies into the Mac OS. In August 1996, Apple chief technology officer Ellen Hancock froze development of Copland and Apple began a search for an operating system developed outside the company. This ultimately led to Apple buying NeXT and developing Rhapsody which would eventually evolve into Mac OS X in 2001 (now named macOS). Mac OS 8.0 Developed under the codename "Tempo", Mac OS 8.0 was released on July 26, 1997. (after being introduced a few days earlier on July 22) The early beta releases of the product which were circulated to developers and Apple internal audiences, were branded as Mac OS 7.7, superseding the then-current release, Mac OS 7.6. The software was renamed Mac OS 8 before final release. Major changes in this version included the Platinum theme, a Finder which was PowerPC-native and multithreaded, and greater customization of the user interface. Other features introduced in Mac OS 8.0 include the following: Customization of system fonts and increased use of the user-set accent color. Pop-up context menus, accessed via ctrl-click with a one-button mouse. Pop-up (or tabbed) windows in the Finder. Spring-loaded folders. Live scrolling. WindowShade widget in window titlebars. Multithreaded Finder — file copy operations run in a separate thread and don't block the Finder UI. Redesigned color picker. Desktop Pictures control panel, allowing photographs to be set as the desktop background; not only tiled patterns. Simple Finder, an option which reduces Finder menus to basic operations, to avoid overwhelming new users. Relocation of the 'Help' menu from an icon at the right end of the menu bar to a standard textual menu positioned after the application's menus. A faster Apple Guide, featuring HTML help pages. Native support of Apple Filing Protocol over IP. Performance improvements to virtual memory, AppleScript execution and system startup times. Faster desktop rebuilding. Mac OS 8.1 Released on January 19, 1998, Mac OS 8.1 was the last version of the Mac OS to run on Motorola 68000 series processors. It addressed performance and reliability improvements. It introduced a new file system named HFS+, also named Mac OS Extended, which supported large file sizes and made more efficient use of larger hard drives via using a smaller block size. To upgrade, users must reformat the hard drive, which deletes the entire contents of the drive. Some third-party utilities later appeared that preserved the user's data while upgrading to HFS+. The 68040 systems do not support booting from HFS+ disks; the boot drive must be HFS. Mac OS 8.1 was the first system to have a Universal Disk Format (UDF) driver, allowing for DVD support on the Mac for the first time. It also shipped with the new Java runtime (JDK 1.13). Mac OS 8.1 also included an enhanced version of PC Exchange, allowing Macintosh users to see the long file names (up to 255 characters) on files that were created on PCs running Microsoft Windows, and supporting FAT32. Mac OS 8.1 is the earliest version of the Mac OS that can run Carbon applications. Carbon support requires a PowerPC processor and installation of the CarbonLib software from Apple's website; it is not a standard component of Mac OS 8.1. Applications needing later versions of CarbonLib will not run on Mac OS 8.1. More recent versions of CarbonLib require Mac OS 8.6. As part of Apple's agreement with Microsoft, 8.1 included Internet Explorer 3 initially, but soon switched to Internet Explorer 4 as its default browser. Mac OS 8.1 was free for Mac OS 8 owners and was available in February 1998 via the apple.com website. Mac OS 8.5 Released October 17, 1998, Mac OS 8.5 was the first version of the Mac OS to run solely on Macs equipped with a PowerPC processor. If Mac OS 8.5 is installed on a 68k system, the Sad Mac error screen will appear. As such, it replaced some, but not all, of the 680x0 code with PowerPC code, improving system performance by relying less on 680x0 emulation. It introduced the Sherlock search utility. This allowed users to search the contents of documents on hard drives (if the user had let it index the drive), or extend a search to the Internet. Sherlock plug-ins started appearing at this time; these allowed users to search the contents of other websites. Mac OS 8.5 includes several performance improvements. Copying files over a network was faster than prior versions and Apple advertised it as being "faster than Windows NT". AppleScript was also rewritten to use only PowerPC code, which improved AppleScript execution speed significantly. Font Smoothing, system-wide antialiasing for type was also introduced. The HTML format for online help, first adopted by the Finder's Info Center in Mac OS 8, was now used throughout. This made it easier for software companies to write online help systems. The PPP control panel was removed and replaced with Remote Access, which provides the same functionality but also allows connections to AppleTalk Remote Access (ARA) servers. The installation process was simplified considerably in Mac OS 8.5. In earlier versions the installer worked in segments and often required a user to click to continue in between stages of the installation. This was a holdover from the days when the OS was distributed on multiple floppy disks, disk swapping promoting a natural segmentation model. The Mac OS 8.5 installer generally required very little user interaction once it was started. Customisation options were also much more detailed yet simpler to manage. From Mac OS 8.5 onward, MacLinkPlus document translation software is no longer bundled as part of the Mac OS. Mac OS 8.5 was the first version of the Mac OS to support themes, or skins, which could change the default Apple Platinum look of the Mac OS to "Gizmo" or "HiTech" themes. This radical changing of the computer's appearance was removed at the last minute, and appeared only in beta versions, though users could still make (and share) their own themes and use them with the OS. The Appearance control panel was also updated to support proportional scroll bars, and added the option for both scroll arrows to be placed at the bottom of a scroll bar. Along with themes support, 8.5 was the first version to support 32-bit icons. Icons now had 24-bit color (16.7 million colors) and an 8-bit alpha channel, allowing for transparency-translucency effects. The application palette made its debut with 8.5 – the application menu at the right side of the menu bar could be resized to show the active application's name, or 'torn off' into a palette of buttons. This palette could be customized in many ways, by removing the window frame and changing the size and layout of the buttons. Apple provided no user interface to set these options, instead making them available via AppleScript and Apple Events and relying on third parties to provide a user interface for the task. By setting it to display horizontally and turning off the window border, the palette's look and function could be configured to resemble the Windows 95 task bar. Mac OS 8.5.1 Mac OS 8.5.1, released December 7, 1998, was a minor update to Mac OS 8.5 that fixes several bugs that caused crashes and data corruption. Mac OS 8.6 Released May 10, 1999, Mac OS 8.6 added support to the Mac OS nanokernel to handle preemptive tasks via the Multiprocessing Services 2.x and later developer API. This update improved PowerBook battery life and added Sherlock 2.1. This free update for Mac users running 8.5 and 8.5.1 was faster and much more stable than either version of 8.5.x and was also the first version of Mac OS to display the version number as part of the startup screen. However, there was still no process separation; the system still used cooperative multitasking between processes, and even a process that is Multiprocessing Services-aware still had a portion that ran in the "blue task", which also ran all programs that were unaware of it, and was the only task that could run 68k code. Versions Compatibility See also List of Apple operating systems Notes References External links from apple.com from apple.com from apple.com from apple.com Mac OS 8 Hardware Compatibility 1997 software Classic Mac OS PowerPC operating systems Microkernel-based operating systems Microkernels

Operating System (OS)

MSDOS.SYS MSDOS.SYS is a system file in MS-DOS and Windows 9x operating systems. In versions of MS-DOS from 1.1x through 6.22, the file comprises the MS-DOS kernel and is responsible for file access and program management. MSDOS.SYS is loaded by the DOS BIOS IO.SYS as part of the boot procedure. In some OEM versions of MS-DOS, the file is named MSDOS.COM. In Windows 95 (MS-DOS 7.0) through Windows ME (MS-DOS 8.0), the DOS kernel has been combined with the DOS BIOS into a single file, IO.SYS (aka WINBOOT.SYS), while MSDOS.SYS became a plain text file containing boot configuration directives instead. If a WINBOOT.INI file exists, the system will retrieve these configuration directives from WINBOOT.INI rather than from MSDOS.SYS. When Windows 9x is installed over a preexisting DOS install, the Windows file may be temporarily named MSDOS.W40 for as long as Windows' dual-boot feature has booted the previous OS. Likewise, the MSDOS.SYS of the older system is named MSDOS.DOS for as long as Windows 9x is active. Some DOS utilities expect the MSDOS.SYS file to have a minimal file size of at least 1 KB. This is the reason why a large dummy comment is typically found in the MSDOS.SYS configuration file since Windows 95. By default, the file is located in the root directory of the bootable drive/partition (normally C:\ for hard disks) and has the hidden, read-only, and system file attributes set. The MS-DOS derivative (DCP) by the former East-German VEB Robotron used a filename instead. IBM PC DOS as well as DR DOS since 5.0 (with the exception of DR-DOS 7.06) used the file IBMDOS.COM for the same purpose, whereas DR DOS 3.31 to 3.41 used DRBDOS.SYS instead. FreeDOS uses the file KERNEL.SYS for the same purpose. Windows NT-based operating systems (NT 3.1–4, 2000, XP, and 2003) use the NTLDR file and NT 6+ operating systems (Vista, 2008, 7, 8, 8.1, and 10) use bootmgr instead, as they have a different boot sequence. See also IO.SYS IBMDOS.COM DRBDOS.SYS COMMAND.COM List of DOS system files Architecture of Windows 9x Notes References External links MSDOS.SYS in Windows 9x (95/98/ME): Microsoft Knowledge Base (MSKB): List of MSDOS.SYS articles MDGx: Windows 95/98/ME Complete MSDOS.SYS Reference UKT Support: Contents of the MSDOS.SYS File Computer Hope: Information about Window MSDOS.SYS file MDGx: WINBOOT.INI DOS kernel DOS files DOS configuration files

Operating System (OS)

Ntoskrnl.exe In computing ntoskrnl.exe (short for Windows NT operating system kernel executable), also known as kernel image, provides the kernel and executive layers of the Microsoft Windows NT kernel space, and is responsible for various system services such as hardware abstraction, process and memory management, thus making it a fundamental part of the system. It contains the cache manager, the executive, the kernel, the security reference monitor, the memory manager, and the scheduler (Dispatcher). Overview This system binary is not a native application (in that it is not linked against ntdll.dll), instead containing a standard 'start' entry point in its-own, a function that calls the architecture-independent kernel initialization function. While ntoskrnl.exe is not linked against ntdll.dll, it is linked against bootvid.dll, hal.dll and kdcom.dll. Because it requires a static copy of C Runtime objects it depends on, the executable is usually about 10 MB in size. Overall, there are four kernel image files for each revision of Windows, and two kernel image files for each Windows system. Multiprocessor or uniprocessor files are selected at install time, and PAE or non-PAE files are selected by boot.ini or BCD option, according to the processor's features. In recent versions of Windows, there is only one ntoskrnl.exe, that covers both SMP and uniprocessor scenarios. Routines in ntoskrnl use prefixes on their names to indicate in which component of ntoskrnl they are defined. The following table lists some of them. Initialization When the kernel receives control, it gets a pointer to a structure as parameter. This structure is passed by the bootloader and contains information about the hardware, the path to the registry file, kernel parameters containing boot preferences or options that change the behavior of the kernel, path of the files loaded by the bootloader (SYSTEM Registry hive, nls for character encoding conversion and vga font). The definition of this structure can be retrieved by using the kernel debugger or downloading it from the Microsoft symbol database. In the x86 architecture, the kernel receives the system already in protected mode, with the GDT, IDT and TSS ready. But since it does not know the address of each one, it has to load them one by one to fill the PCR structure. The main entry point of ntoskrnl.exe performs some system dependent initialization then calls a system independent initialization then enters an idle loop. Interrupt handling Modern operating systems use interrupts instead of I/O port polling to wait for information from devices. In the x86 architecture, interrupts are handled through the Interrupt Dispatch Table (IDT). When a device triggers an interrupt and the interrupt flag (IF) in the FLAGS register is set, the processor's hardware looks for an interrupt handler in the table entry corresponding to the interrupt number to which in turn has been translated from IRQ by PIC chips, or in more modern hardwares, APIC. Interrupt handlers usually save some subset of the state of registers before handling it and restore them back to their original values when done. The interrupt table contains handlers for hardware interrupts, software interrupts, and exceptions. For some IA-32 versions of the kernel, one example of such a software interrupt handler (of which there are many) is in its IDT table entry 2E16 (hexadecimal; 46 in decimal), used in assembly language as INT 2EH for system calls. In the real implementation the entry points to an internal subroutine named (as per symbol information published by Microsoft) KiSystemService. For newer versions, different mechanisms making use of SYSENTER instruction and in x86-64 SYSCALL instruction are used instead. One notable feature of NT's interrupt handling is that interrupts are usually conditionally masked based on their priority (called "IRQL"), instead of disabling all IRQs via the interrupt flag. This permits various kernel components to carry on critical operations without necessarily blocking services of peripherals and other devices. Memory manager Microsoft Windows divides virtual address space into two regions. The lower part, starting at zero, is instantiated separately for each process and is accessible from both user and kernel mode. Application programs run in processes and supply code that runs in user mode. The upper part is accessible only from kernel mode, and with some exceptions, is instantiated just once, system-wide. Ntoskrnl.exe is mapped into this region, as are several other kernel mode components. This region also contains data used by kernel mode code, such as the kernel mode heaps and the file system cache. The entire physical memory (RAM) address range is broken into many small (usually 4 KB) blocks. A few of the properties of each block are stored in structures called page table entries, which are managed by the OS and accessed by the processor's hardware. Page tables are organized into a tree structure, and the physical page number of the top-level table is stored in control register 3 (CR3). Registry Windows Registry is a repository for configuration and settings information for the operating system and for other software, such as applications. It can be thought of as a filesystem optimized for small files. However, it is not accessed through file system-like semantics, but rather through a specialized set of APIs, implemented in kernel mode and exposed to user mode. The registry is stored on disk as several different files called "hives." One, the System hive, is loaded early in the boot sequence and provides configuration information required at that time. Additional registry hives, providing software-specific and user-specific data, are loaded during later phases of system initialization and during user login, respectively. Drivers The list of drivers to be loaded from the disk are retrieved from the Services key of the current control set's key in the SYSTEM registry hive. That key stores device drivers, kernel processes and user processes. They are all collectively called "services" and are all stored mixed on the same place. During initialization or upon driver load request, the kernel traverses that tree looking for services tagged as kernel services. See also Architecture of Windows NT Windows NT Startup Process Notes References Further reading External links Inside the Windows Vista Kernel (TechNet Magazine) struct LOADER_PARAMETER_BLOCK Driver Development Part 1: Introduction to Drivers Windows NT kernel Windows files

Operating System (OS)

GEOS (16-bit operating system) GEOS (later renamed GeoWorks Ensemble, NewDeal Office, and Breadbox Ensemble) is a computer operating environment, graphical user interface (GUI), and suite of application software. Originally released as PC/GEOS, it runs on DOS-based, IBM PC compatible computers. Versions for some handheld platforms were also released and licensed to some companies. PC/GEOS was first created by Berkeley Softworks, which later became GeoWorks Corporation. Version 4.0 was developed in 2001 by Breadbox Computer Company, limited liability company (LLC), and was renamed Breadbox Ensemble. In 2015, Frank Fischer, the CEO of Breadbox, died and efforts on the operating system stopped until later in 2017 when it was bought by blueway.Softworks. PC/GEOS should not be confused with the 8-bit GEOS product from the same company, which runs on the Commodore 64 and Apple II. PC/GEOS GeoWorks Ensemble In 1990, GeoWorks released PC/GEOS for IBM PC compatible systems. Commonly referred to as GeoWorks Ensemble, it was incompatible with the earlier 8-bit versions of GEOS for Commodore and Apple II computers, but provided numerous enhancements, including scalable fonts and multitasking on IBM PC XT- and AT-class PC clones. GeoWorks saw a market opportunity to provide a graphical user interface for the 16 million older model PCs that were unable to run Microsoft Windows 2.x. GEOS was packaged with a suite of productivity applications. Each had a name prefixed by "Geo": GeoWrite, GeoDraw; GeoManager; GeoPlanner; GeoDex, and GeoComm. It was also bundled with many PCs at the time, but like other GUI environments for the PC platform, such as Graphics Environment Manager (GEM), it ultimately proved less successful in the marketplace than Windows. Former CEO of GeoWorks claims that GEOS faded away "because Microsoft threatened to withdraw supply of MS-DOS to hardware manufacturers who bundled Geoworks with their machines". In December 1992, NEC and Sony bundled an original equipment manufacturer (OEM) version of GeoWorks named the CD Manager with their respective CD-ROM players that sold as retail box add-on peripherals for consumers. The NEC Bundle retailed for around $500.00 with a 1x external CD-ROM, Small Computer System Interface (SCSI) interface controller, Labtec CD-150 amplified stereo speakers and 10 software titles. A scaled-down version of GeoWorks was used by America Online for their DOS-based AOL client software from the time of introduction on IBM compatible PCs until the late 1990s when America Online dropped development for graphical DOS in favor of Microsoft Windows. During that time, the popular single 3.5" self-booting disk that AOL was distributing could be hacked to boot the GeoWorks environment. IBM released the PC/GEOS-based EduQuest SchoolView network management tool for K-12 schools in 1994. Negotiations to make PC/GEOS an integral part of PC DOS 7.0 failed. GeoWorks attempted to get third-party developers but was unable to get much support due to expense of the developer kit, which cost $1,000 for the manuals only, and the difficult programming environment, which required a second PC networked via serial port to run the debugger. Even though PC/GEOS is referred to as an "operating system", it still requires DOS in load. GEOS and its applications were written in a mix of 8086 assembly language (Espire) and C (GEOS Object C: GOC), both with non-standard language extensions to support the object-oriented design. Under DR DOS 6.0, if TASKMAX was loaded before PC/GEOS, PC/GEOS registered as graphical menu system for TASKMAX. This still worked under the pre-emptive multitasker (EMM386 /MULTI + TASKMGR) provided by Novell DOS 7, OpenDOS 7.01 and DR-DOS 7.02 (and higher), allowing for multiple GEOS and DOS applications to run concurrently. After release of Ensemble 2.01, GeoWorks ended support for the desktop version to focus on handhelds and smart devices. Geoworks Ensemble won the 1991 Software Publishers Association Excellence in Software Award for Best Consumer Program. NewDeal Office A newer version of PC/GEOS was marketed in the late 1990s as NewDeal Office from NewDeal Inc. in hopes of creating a market among owners of i386, i486 and Pentium PCs that could not run Windows 95 or Windows 98 effectively. NewDeal released 3 new versions of NewDeal Office (NewDeal Office 2.5, NewDeal Office 3/98 and NewDeal Office 2000) until it went bankrupt in 2000. NDO or NDO 2000 came with a webbrowser named Skipper or Skipper 2000, respectively. Breadbox Ensemble After "NewDeal Inc." went out of business, Breadbox purchased the rights in the software from GeoWorks in 2001. Their newest PC/GEOS, 4.x, is now a full productivity and internet suite, including web browser (named WebMagick) as well as email. Other essential programs such as word processing, spreadsheet, flat file database and graphics applications are integrated into this package. On 14 November 2015, Frank S. Fischer, the CEO and owner of Breadbox Ensemble LLC, died of a heart attack, some while after announcing plans to bring GEOS to Android. Versions 1990: OS/90 beta version 1990: geoDOS beta version 1990: GeoWorks 1.0 1991: GeoWorks 1.2 1992: GeoWorks 1.2 Pro (with Borland Quattro Pro for DOS with PC/GEOS "Look and Feel") 1992: GeoWorks DTP 1992: GeoWorks CD Manager 1993: GeoWorks Ensemble 2.0 (new kernel PC/GEOS 2.0) 1993: Geopublish 2.0 1994: Geoworks Ensemble 2.01 1996: NewDeal Office 2.2 1996: NewDeal Office 2.5 1996: NewDeal Publish 2.5 shareware version 1997: NewDeal Office 97 1998: NewDeal Office 98 1999: NewDeal Office release 3 (new kernel PC/GEOS 3.0) 1999: NewDeal Office release 3 evaluation 1999: NewDeal Office 3.2 2000: NewDeal Office 3.2d (German patch) 2000: NewDeal Office 2000 (new kernel PC/GEOS 4.0) 2000: NewDeal Office 2000 for (for a Surf´n´Office PC from Ted Turner IV (MyTurn, Inc.) with help from CNN) 2001: BreadBox Ensemble beta version 4.0.1.1 2001: BreadBox Ensemble beta version 4.0.1.x 2002: Breadbox Ensemble beta version 4.0.2.0 2005–March: Breadbox Ensemble version 4.1.0.0 2005–November: Breadbox Ensemble version 4.1.2.0 2009–August: Breadbox Ensemble version 4.1.3.0 PEN/GEOS PEN/GEOS 1.0 was the new name for PC/GEOS 2.0 when GeoWorks released it on 9 April 1992. PEN/GEOS 1.0 was a pioneering personal digital assistant (PDA) technology. GEOS was also used in the low-end GeoBook laptop from Brother Industries and in several Nokia Communicator models (GEOS 3.0 in models 9000, 9110). PEN/GEOS 2.0 was released in 1992, and version 3.0 was released in 1995. Zoomer devices; Tandy Z-PDA, AST GRiDPad 2390, Casio Z-7000 & XL 7000 PEN/GEOS 1.0 was used as the operating system for the Tandy Corporation Z-PDA, which was introduced shortly after the first Apple Newton MessagePad. Palm Computing had been incorporated to create software for this device and shipped its first handwriting recognition software, PalmPrint, personal information manager, Palm Organizer, and synchronization software, PalmConnect, on the Z-PDA. Palm Organizer included the PalmSchedule date book, PalmAddress address book, PalmNotes notebook, a dictionary, calculator, clock, forms calculator, 26 language translation dictionary, on-line help, holiday, and travel information. The device was also sold under license as the AST GRiDPad 2390 and as the Casio Z-7000 which was the best selling version. In the US, Casio sold it under the name XL-7000 without the multi-lingual interface, but added an AOL client and some USA specific help files. These devices were all named Zoomer and were the first PDAs with a connection to the online services CompuServe and AOL. This was made possible through the pre-installed dial-up software CompuServeAOL. HP OmniGo 100 & 120 In 1993, GeoWorks released PEN/GEOS 2.0, again based on PC/GEOS 2.0. In 1995, this version of GEOS appeared (running on top of DOS) on the HP OmniGo 100. It featured Graffiti handwriting recognition. The OmniGo is a flip-around clamshell handheld computer powered by a Vadem VG230 integrated PC-on-a-chip. The VG230 chip includes an Intel 80186-instruction set compatible NEC V30 core. It was soon followed by the HP OmniGo 120, which added a high-contrast screen. Brother LW-Writing System Brother LW-screen typewriters use PEN/GEOS and are the only version of the operating system that ships with vendor-provided drivers for scanner and it included a GEOS scanning application. In Germany, the Brother LW750ic system is equipped with PEN/GEOS. Brother GeoBook In 1997, Brother, in collaboration with IBM, brought the GeoBook series of notebooks to market. GeoBook models NB-60, NB-80C, and PN-9100GR used a modified version of PEN/GEOS using the Yago user interface. The GeoBook series was marketed mainly in education and was part of the IBM Eduquest School View strategy. Nokia Communicator 9000(i) and 9110(i) In 1996, the Nokia 9000 Communicator smartphone was introduced. This phone uses PEN/GEOS 3.0 and established the smartphone market. Nokia followed with Communicator models 9000i, 9110, and 9110i. GEOS-SC GEOS-SC was a 32-bit reduced instruction set computer (RISC) CPU smartphone, OS, and GUI for the Japanese cellphone market. It was released in 1997. Originally built as GeoWorks' planned future OS and codenamed 'Liberty', GEOS-SC became the basis for cellphones designed by Mitsubishi Electric Company (MELCO) of Japan. GEOS-SE Alongside this, GEOS-SE which was an OS designed and developed by Eden Ltd., a UK-based company acquired in 1997 by Geoworks. It became the basis of several other devices, most notably the Seiko Epson Locatio which was a multifunction device incorporating browser, PIM software, phone, GPS and Camera. It was launched in Japan in 1998. FreeGEOS Since 2016, the source code of PC/GEOS has been made available as FreeGEOS and can be compiled and edited freely. References Further reading GEOWORKS. (1990). "Product Packaging (a printed card box with corrugated card liner) Part number: 16-2001-0101 Bar Code: 0 14233 20010 6". GeoWorks, Berkeley, CA 94704. Oerttel, Burkhard. Das große Buch zu GeoWorks Pro, Ensemble & DTP, Data Becker GmbH, 1992, . Oerttel, Burkhard. Das große Buch zu GeoWorks 2.0, Data Becker GmbH, 1994, . Wegen, Andreas. GeoWorks DTP, Pro, Ensemble, te-wi Verlag bzw. TLC The Learning Companie, Series: Grundlagen und Praxis - Betriebssysteme, 1992, . Wegen, Andreas. GeoWorks 2.0 - Bedienung, Applikationen, Beispiele, Tips, Interna, Referenz, te-wi Verlag, 1993, . Seibert, Axel. GeoWorks - Ensemble Erfolgreich starten - sicher nutzen, Markt & Technik Verlag München, Series: Workshop - PC, 1991, . Roßkamp, Alfred. GeoWorks Ensemble - Einführung in die Benutzerschnittstelle, Deutscher Taschenbuch Verlag (dtv), Series: Beck EDV-Berater im dtv (Basiswissen - GeoWorks), 1993, . Bartel, Rainer. GeoWorks 1.2 & Pro - Der Einstieg in 20 Schritten, Sybex Verlag Düsseldorf, Series: Quick Start, 1992, . Schölles, Reiner. GeoWorks 2.0 - Schnellanleitung, Data Becker GmbH, 1994, . External links Usenet Breadbox Computer Company, former developer and publisher of GEOS GEOS FAQ GEOS-InfoBase blueway.Softworks DOS software Formerly proprietary software Graphical user interfaces Mobile operating systems Operating system APIs Software using the Apache license Assembly language software Window-based operating systems X86 operating systems 1990 software cs:GEOS

Operating System (OS)

PenPoint OS The PenPoint OS was a product of GO Corporation and was one of the earliest operating systems written specifically for graphical tablets and personal digital assistants. It ran on AT&T Corporation's EO Personal Communicator as well as a number of Intel x86 powered tablet PCs including IBM's ThinkPad 700T series, NCR's 3125, 3130 and some of GRiD Systems' pen-based portables. It was never widely adopted. Developers of the PenPoint OS included Robert Carr, who was involved with the Alto computer at Xerox PARC. He commissioned Dr. Tinker, the naming service company of Mark Beaulieu who generated the name 'PenPoint', using proprietary algorithms. Awards and innovation Byte magazine awarded PenPoint best Operating System in the 1992 Byte Awards. PenPoint won in the Standards and Operating Systems category in PC Magazine's 1991 Technical Excellence awards. The PenPoint operating system had novel early implementations of several computing advances, including: a large set of gestures such as circle to edit, X to delete, and caret to insert using the same gestures at all levels of the operating system and applications press and hold for moving any selection, which showed the selection as a floating icon to be dropped into a destination a rich notebook user interface metaphor: Documents existed as pages in a notebook with tabs (this was not new in PenPoint, but PenPoint was the first to make it a primary OS interface; Microsoft later did it in Windows for Pen Computing) a document architecture where each document was a directory nested in another document's directory (in some sense, this was an extension of the document architecture on Multics) dynamic toolkit layout: this allowed applications to rescale for landscape and portrait orientation a system-wide pluggable address book In April 2008, as part of a larger federal court case, the gesture features of the Windows/Tablet PC operating system and hardware were found to infringe on a patent by GO Corp. concerning user interfaces for the PenPoint OS. Third-party applications The novel user interface of PenPoint and the mobile form factor of pen computers inspired many startup software companies, including: Inkwriter by Aha! Software which was purchased by Microsoft and became the basis for Microsoft's Windows Journal FutureWave Software (SmartSketch, a vector-drawing program that evolved into Adobe Flash) Glyphic Technology (Glyphic Script prototype-based programming language, with Codeworks direct interactive programming environment) PenMagic (Numero spreadsheet and LetterExpress document fill-in templates) Pensoft (Perspective personal data manager, winner of a BYTE award in 1992). Pensoft was acquired by Eo. Slate (several pen applications). Slate's founders included industry luminaries Dan Bricklin and Bob Frankston. Gaia Software (Personal Media personal productivity applications) Conic Systems (LocatorGIS survey/mapping application that briefly went into production at Ordnance Survey in the UK) Ink Development released InkWare NoteTaker and InkWare Photo. Pierre Omidyar and Greg Stein were two of the founders. Ink Development renamed themselves eShop when they pivoted to electronic commerce software and was later acquired by Microsoft. Marathon Development created QuikScript, the original script handwriting word processor. QuikScript was later ported to Palm and Windows devices under the name PenScript. Patents acquired by Microsoft. References Further reading External links Thoughts on The Power of PenPoint Archive Startup: A Silicon Valley Adventure Barbarians led by Bill Gates — Contains two chapters dealing with the story of GO Corporation and the PenPoint OS from a view inside Microsoft. Microsoft found to infringe PenPoint gesture patent Annotated bibliography of references to handwriting recognition and tablet and touch computers Personal digital assistant software Handwriting recognition 1991 software

Operating System (OS)

OpenVMS OpenVMS, often referred to as just VMS, is a multi-user, multiprocessing virtual memory-based operating system designed to support time-sharing, batch processing, transaction processing and workstation applications. It was first announced by Digital Equipment Corporation (DEC) as VAX/VMS (Virtual Address eXtension/Virtual Memory System) alongside the VAX-11/780 minicomputer in 1977. OpenVMS has subsequently been ported to run on DEC Alpha systems, the Itanium-based HPE Integrity Servers, and select x86-64 hardware and hypervisors. Since 2014, OpenVMS is developed and supported by a company named VMS Software Inc. (VSI). OpenVMS offers high availability through clustering and the ability to distribute the system over multiple physical machines. This allows clustered applications and data to remain continuously available while operating system software and hardware maintenance and upgrades are performed, or when a whole data center is destroyed. VMS cluster uptimes of 17 years have been reported. Customers using OpenVMS include banks and financial services, hospitals and healthcare, telecommunications operators, network information services, and industrial manufacturers. During the 1990s and 2000s, there were approximately half a million VMS systems in operation worldwide. History Origin and name changes In April 1975, Digital Equipment Corporation embarked on a hardware project, code named Star, to design a 32-bit virtual address extension to its PDP-11 computer line. A companion software project, code named Starlet, was started in June 1975 to develop a totally new operating system, based on RSX-11M, for the Star family of processors. These two projects were tightly integrated from the beginning. Gordon Bell was the VP lead on the VAX hardware and its architecture. Roger Gourd was the project lead for the Starlet program, with software engineers Dave Cutler (who would later lead development of Microsoft's Windows NT), Dick Hustvedt, and Peter Lipman acting as the technical project leaders, each having responsibility for a different area of the operating system. The Star and Starlet projects culminated in the VAX-11/780 computer and the VAX/VMS operating system. The Starlet name survived in VMS as a name of several of the main system libraries, including STARLET.OLB and STARLET.MLB. In September 1984, Digital created a dedicated distribution of VMS named MicroVMS for the MicroVAX and VAXstation, which had significantly less memory and disk space than larger VAX systems of the time. MicroVMS split up VAX/VMS into multiple kits, which a customer could use to install a subset of VAX/VMS tailored to their specific requirements. MicroVMS also differed by various simplifications to the setup and management of the operating system, and came with a condensed documentation set. MicroVMS kits were released on TK50 tapes and RX50 floppy disks, corresponding to VAX/VMS V4.0 to V4.7. MicroVMS was merged back into VAX/VMS in the V5.0 release, by which time the ability to customize a VAX/VMS installation had advanced to a point where MicroVMS became redundant. Beginning in 1989, a short lived distribution of VMS named Desktop-VMS was sold with VAXstation systems. It consisted of a single CD-ROM containing a bundle of VMS, DECwindows, DECnet, VAXcluster support, and a setup process designed for non-technical users. Desktop-VMS could either be run directly from the CD, or could be installed onto a hard drive. Desktop-VMS had its own versioning scheme beginning with V1.0, which corresponded to the V5.x releases of VMS. With the V5.0 release in April 1988, DEC began to refer to VAX/VMS as simply VMS in its documentation. In July 1992, DEC renamed VAX/VMS to OpenVMS as an indication for its support of "open systems" industry standards such as POSIX and Unix compatibility, and to drop the VAX connection since the port to Alpha was underway. The OpenVMS name was first used with the OpenVMS AXP V1.0 release in November 1992. DEC began using the OpenVMS VAX name with the V6.0 release in June 1993. Port to DEC Alpha During the 1980s, DEC planned to replace the VAX platform and the VMS operating system with the PRISM architecture and the MICA operating system. When these projects were cancelled in 1988, a team was set up to design new VAX/VMS systems of comparable performance to RISC-based Unix systems. After a number of failed attempts to design a faster VAX-compatible processor, the group demonstrated the feasibility of porting VMS and its applications to a RISC architecture based on PRISM. This led to the creation of the Alpha architecture. The project to port VMS to Alpha began in 1989, and first booted on a prototype Alpha EV3-based Alpha Demonstration Unit in early 1991. Prior to the availability of Alpha hardware, the Alpha port was developed and booted on an emulator named Mannequin, which implemented many of the Alpha instructions in custom microcode on a VAX 8800 system. The main challenge in porting VMS to a new architecture was that VMS and the VAX were designed together, meaning that VMS was dependent on certain details of the VAX architecture. Furthermore, a significant amount of the VMS kernel, layered products, and customer-developed applications were implemented in VAX MACRO assembly code. Some of the changes needed to decouple VMS from the VAX architecture included: The creation of the MACRO-32 compiler, which treated VAX MACRO as a high-level language, and compiled it to Alpha object code. The creation of a VAX to Alpha binary translator, known as the VAX Environment Software Translator (VEST), which was capable of translating VAX executables when it was not possible to recompile the code for Alpha. The emulation of certain low-level details of the VAX architecture in PALcode, such as interrupt handling and atomic queue instructions. This decreased the amount of VAX-dependent code which had to be rewritten for Alpha. The conversion of the VMS compilers, many of which had their own bespoke VAX code generators, to use a common compiler backend named GEM. The VMS port to Alpha resulted in the creation of two separate source code libraries (based on a source code management tool known as the VMS Development Environment, or VDE) for VAX, and for Alpha. The Alpha code library was based on a snapshot of the VAX/VMS code base circa V5.4-2. 1992 saw the release of the first version of OpenVMS for Alpha AXP systems, designated OpenVMS AXP V1.0. In 1994, with the release of OpenVMS V6.1, feature (and version number) parity between the VAX and Alpha variants was achieved, this was the so-called Functional Equivalence release. The decision to use the 1.x version numbering stream for the pre-production quality releases of OpenVMS AXP caused confusion for some customers, and was not repeated in the subsequent ports of OpenVMS to new platforms. When VMS was ported to Alpha, it was initially left as a 32-bit only operating system. This was done to ensure backwards compatibility with software written for the 32-bit VAX. 64-bit addressing was first added for Alpha in the V7.0 release. In order to allow 64-bit code to interoperate with older 32-bit code, OpenVMS does not create a distinction between 32-bit and 64-bit executables, but instead allows for both 32-bit and 64-bit pointers to be used within the same code. This is known as mixed pointer support. The 64-bit OpenVMS Alpha releases support a maximum virtual address space size of 8TiB (a 43-bit address space), which is the maximum supported by the Alpha 21064 and Alpha 21164. One of the more noteworthy Alpha-only features of OpenVMS was OpenVMS Galaxy - which allowed the partitioning of a single SMP server to run multiple instances of OpenVMS. Galaxy supported dynamic resource allocation to running partitions, and the ability to share memory between partitions. Port to Intel Itanium In 2001, prior to its acquisition by Hewlett-Packard, Compaq announced the port of OpenVMS to the Intel Itanium architecture. The Itanium port was the result of Compaq's decision to discontinue future development of the Alpha architecture in favour of adopting the then-new Itanium architecture. The porting began in late 2001, and the first boot on took place on the 31st of January 2003. The first boot consisted of booting a minimal system configuration on a HP i2000 workstation, logging in as the SYSTEM user, and running the DIRECTORY command. The Itanium port of OpenVMS supports specific models and configurations of HPE Integrity Servers. The Itanium releases were originally named HP OpenVMS Industry Standard 64 for Integrity Servers, although the names OpenVMS I64 or OpenVMS for Integrity Servers are more commonly used. The Itanium port was accomplished using source code maintained in common within the OpenVMS Alpha source code library, with the addition of conditional code and additional modules where changes specific to Itanium were required. Whereas the VAX and Alpha architectures were specifically designed to support the low-level needs of OpenVMS, Itanium was not. This required certain architectural dependencies of OpenVMS to be replaced, or emulated in software. Some of the changes included: The Extensible Firmware Interface (EFI) is used to boot OpenVMS on Integrity hardware, taking over the role of the System Reference Manual (SRM) firmware on Alpha. Support for ACPI was also added to OpenVMS, since this is used to discover and manage hardware devices on the Integrity platform. For Itanium, the functionality which was implemented using PALcode for Alpha was moved into a component of the OpenVMS kernel named the Software Interrupt Services (SWIS). The Itanium port adopted a new calling standard based on Intel's Itanium calling convention, with extensions to support the OpenVMS Common Language Environment. Furthermore, it replaced the OpenVMS-specific executable formats used on the VAX and Alpha with the standard Executable and Linking Format (ELF) and DWARF formats. IEEE 754 was adopted as the default floating point format, replacing the VAX floating point format that was the default on both the VAX and Alpha architectures. For backwards compatibility, it is possible to compile code on Itanium to use the VAX floating point format, but it relies on software emulation. The operating system was modified to support the 50-bit physical addressing available on Itanium, allowing 1PiB of memory to be addressed. The Itanium port otherwise retained the mixed 32-bit/64-bit pointer architecture which was introduced in OpenVMS Alpha V7.0. As with the VAX to Alpha port, a binary translator for Alpha to Itanium was made available, allowing user mode OpenVMS Alpha software to be ported to Itanium in situations where it was not possible to recompile the source code. This translator is known as the Alpha Environment Software Translator (AEST), and it also supported translating VAX executables which had already translated with VEST. Two pre-production releases, OpenVMS I64 V8.0 and V8.1, were available on June 30, 2003 and on December 18, 2003. These releases were intended for HP organizations and third-party vendors involved with porting software packages to OpenVMS I64. The first production release, V8.2, was released in February 2005. V8.2 was also released for Alpha, subsequent V8.x releases of OpenVMS have maintained feature parity between the Alpha and Itanium architectures. Port to x86-64 When VMS Software Inc. (VSI) announced that they had secured the rights to develop the OpenVMS operating system from HP, they also announced their intention to port OpenVMS to the x86-64 architecture. The porting effort ran concurrently with the establishment of the company, as well as the development of VSI's own Itanium and Alpha releases of OpenVMS V8.4-x. The x86-64 port is targeted for specific servers from HPE and Dell, as well as certain virtual machine hypervisors. Initial support was targeted for KVM and VirtualBox. Support for VMware was announced in 2020, and Hyper-V has been described as a future target. In 2021, the x86-64 port was demonstrated running on an Intel Atom-based single-board computer. The x86-64 port is built from the same source code library as the Alpha and Itanium architectures, using conditional compilation to manage the architecture-specific code needed to support the x86-64 platform. As with the Alpha and Itanium ports, the x86-64 port made some changes to simplify porting and supporting OpenVMS on the new platform: VSI adopted the open source LLVM compiler backend, replacing the proprietary GEM backend used in the Alpha and Itanium ports. A translator was developed to map the GEM IR to LLVM IR, allowing the existing compiler frontends to be reused. In addition, the open source Clang compiler was adopted as the officially supported C++ compiler for OpenVMS under x86-64. On x86-64, OpenVMS makes more extensive use of UEFI and ACPI to detect and initialize hardware on boot. As part of this, VMS is now booted from a memory disk, instead of the traditional VMS boot mechanism – which relied on boot drivers containing a basic implementation of the filesystem, and which was tied to specific hardware devices. The changes to the boot process necessitated the creation of a Dump Kernel – this is a secondary kernel which is loaded in the background at boot time, and is invoked in case OpenVMS needs to write a crash dump to disk. OpenVMS assumes the presence of four hardware-provided privilege levels to provide isolation between user applications, and various parts of the operating system. While x86-64 nominally provides four privilege levels, they are only equivalent to two of the privilege levels on the VAX, Alpha and Itanium. In the x86-64 port, the Software Interrupt Services (SWIS) module of the kernel is extended to emulate the missing privilege levels. As with the Itanium port, the calling standard for x86-64 is an extension of the platform's standard calling convention, specifically the System V AMD64 ABI. Certain characteristics of the x86-64 architecture created challenges for defining a suitable calling standard. For example, due to the small number of general purpose registers for x86-64, the MACRO-32 compiler has to store the contents of the emulated VAX registers in an in-memory "pseudo registers" structure instead of using the processor's hardware registers as is done on Alpha and Itanium. The first boot was announced on 14 May 2019. This involved booting OpenVMS on VirtualBox, and successfully running the DIRECTORY command. Later in 2019, the first "real boot" was announced - this consisted of the operating system booting in a completely standard manner, a user logging into the system, and running the DIRECTORY command. In May 2020, the V9.0 Early Adopter's Kit release was made available to a small number of customers. This consisted of the OpenVMS operating system running in a VirtualBox VM with certain limitations - most significantly, few layered products were available, and code can only be compiled for x86-64 using cross compilers which run on Itanium-based OpenVMS systems. Following the V9.0 release, VSI released a series of updates on a monthly or bimonthly basis which added additional functionality and hypervisor support. These were designated V9.0-A through V9.0-H. In June 2021, VSI released the V9.1 Field Test, which is available to VSI's customers and partners. V9.1 shipped as an ISO image which can be installed onto a variety of hypervisors, and onto HPE ProLiant DL380 servers starting with the V9.1-A release. Architecture The OpenVMS operating system has a layered architecture, consisting of a privileged Executive, a Command Language Interpreter which runs at an intermediate level of privilege, and utilities and run-time libraries (RTLs) which run in an unprivileged mode, but can potentially run at a higher level of privilege if authorized to do so. Unprivileged code typically invokes the functionality of the Executive through system services (equivalent to system calls in other operating systems). OpenVMS' layers and mechanisms are built around certain features of the VAX architecture, including: The availability of four processor access modes (named Kernel, Executive, Supervisor and User, in order of decreasing privilege). Each mode has its own stack, and each memory page can have memory protections specified per-mode. A virtual address space which is partitioned between process-private space sections, and system space sections which are common to all processes. 32 interrupt priority levels which are used for synchronization. Hardware support for delivering asynchronous system traps to processes. These VAX architecture mechanisms are implemented on Alpha, Itanium and x86-64 by either mapping to corresponding hardware mechanisms on those architectures, or through emulation (via PALcode on Alpha, or in software on Itanium and x86-64). Executive and Kernel The OpenVMS Executive comprises the privileged code and data structures which reside in the system space. The Executive is further subdivided between the Kernel, which consists of the code which runs at the kernel access mode, and the less-privileged code outside of the Kernel which runs at the executive access mode. The components of the Executive which run at executive access mode include the Record Management Services, and certain system services such as image activation. The main distinction between the kernel and executive access modes is that most of the operating system's core data structures can be read from executive mode, but require kernel mode to be written to. Code running at executive mode can switch to kernel mode at will, meaning that the barrier between the kernel and executive modes is intended as a safeguard against accidental corruption as opposed to a security mechanism. The Kernel comprises the operating system's core data structures (e.g. page tables, the I/O database and scheduling data), and the routines which operate on these structures. The Kernel is typically described as having three major subsystems: I/O, Process and Time Management, Memory Management. In addition, other functionality such as logical name management, synchronization and system service dispatch are implemented inside the Kernel. Extension mechanisms OpenVMS allows user mode code with suitable privileges to switch to executive or kernel mode using the $CMEXEC and $CMKRNL system services, respectively. This allows code outside of system space to have direct access to the Executive's routines and system services. In addition to allowing third-party extensions to the operating system, Privileged Images are used by core operating system utilities to manipulate operating system data structures through undocumented interfaces. OpenVMS also allows Shareable Images (i.e. shared libraries) to be granted privilege, allowing the creation of user-written system services, which are privileged routines which can be linked into a non-privileged program. User written system services are invoked using the same mechanism as standard system services, which prevents the unprivileged program from gaining the privileges of the code in the Privileged Shareable Image. Despite what the name may suggest, user-written system services are also used to implement infrequently-used operating system functionality such as volume mounting. OpenVMS provides a device driver interface, which allows support for new I/O devices to be added to the operating system. File system The typical user and application interface into the file system is the Record Management Services (RMS), although applications can interface directly with the underlying file system through the QIO system services. RMS supports multiple record-oriented file access methods and record formats (including fixed length, variable length, and a stream format where the file is treated as a stream of bytes, similar to Unix). RMS also supports remote file access via DECnet, and optional support for journaling. The file systems supported by VMS are referred to as the Files-11 On-Disk Structures (ODS), which provide disk quotas, access control lists and file versioning. The most significant structure levels are ODS-2, which is the original VMS file system, and ODS-5, which extends ODS-2 with support for Unicode file names, case sensitivity, hard links and symbolic links. VMS is also capable of accessing files on ISO 9660 CD-ROMs and magnetic tape with ANSI tape labels. Alongside the OpenVMS Alpha V7.0 release in 1995, DEC released a log-structured file system named Spiralog which was intended as a potential successor to Files-11. Spiralog shipped as an optional product, and was discontinued at the release of OpenVMS Alpha 7.2. Spiralog's discontinuation was due to a variety of problems, including issues with handling full volumes. The developers of Spiralog began work on a new file system in 1996, which was put on hold and later resumed by VSI in 2016 as the VMS Advanced File System (VAFS, not to be confused with DEC's AdvFS for Tru64). VAFS no longer appears on recent roadmaps, and instead VSI have discussed porting the open source GFS2 file system to OpenVMS. One of the major motivations for replacing the Files-11 structures is that they are limited to 2TiB volumes. Command Language Interpreter An OpenVMS Command Language Interpreter (CLI) implements a command line interface for OpenVMS; responsible for executing individual commands, as well as command procedures (equivalent to shell scripts or batch files). The standard CLI for OpenVMS is the DIGITAL Command Language, although other options are available as well. Unlike Unix shells, which typically run in their own isolated process and behave like any other user mode program, OpenVMS CLIs are an optional component of a process, which exist alongside any executable image which that process may run. Whereas a Unix shell will typically run executables by creating a separate process using fork-exec, an OpenVMS CLI will typically load the executable image into the same process, transfer control to the image, and ensure that control is transferred back to CLI once the image has exited and that the process is returned to its original state. A CLI gets mapped into a process' private address space through execution of the LOGINOUT image, which can either be executed manually, or automatically by certain system services for process creation. Due to the fact that the CLI is loaded into the same address space as user code, and that the CLI is responsible for invoking image activation and image rundown, the CLI is mapped into the process address space at supervisor access mode. This is in order to prevent accidental or malicious manipulation of the CLI's code and data structures by user mode code. Features Clustering OpenVMS supports clustering (first called VAXcluster and later VMScluster), where multiple systems run their own instance of the operating system, but share disk storage, processing, a distributed lock manager, a common management and security domain, job queues and print queues, providing a single system image abstraction. The systems are connected either by proprietary specialized hardware (Cluster Interconnect) or an industry-standard Ethernet LAN. OpenVMS supports up to 96 nodes in a single cluster, and allows mixed-architecture clusters, where VAX and Alpha systems, or Alpha and Itanium systems can co-exist in a single cluster. VMS clusters allow the creation of applications which can withstand planned or unplanned outages of part of the cluster. Networking The DECnet protocol suite is tightly integrated into VMS, allowing remote logins, as well as transparent access to files, printers and other resources on VMS systems over a network. Modern versions of VMS support both the traditional Phase IV DECnet protocol, as well as the OSI-compatible Phase V (also known as DECnet-Plus). Support for TCP/IP is provided by the optional TCP/IP Services for OpenVMS layered product (originally known as the VMS/ULTRIX Connection, then as the ULTRIX Communications Extensions or UCX). TCP/IP Services is based on a port of the BSD network stack to OpenVMS, along with support for common protocols such as SSH, DHCP, FTP and SMTP. Due to the fact that the official TCP/IP stack was not introduced until 1988, and the limited feature set of the early versions, multiple third party TCP/IP stacks were created for VMS. DEC sold a software package named PATHWORKS (originally known as the Personal Computer Systems Architecture or PCSA) which allowed personal computers running MS-DOS, Microsoft Windows or OS/2, or the Apple Macintosh to serve as a terminal for VMS systems, or to use VMS systems as a file or print server. PATHWORKS was based on LAN Manager and supported either DECnet or TCP/IP as a transport protocol. PATHWORKS was later renamed to Advanced Server for OpenVMS, and was eventually replaced with a VMS port of Samba at the time of the Itanium port. DEC provided the Local Area Transport (LAT) protocol which allowed remote terminals and printers to be attached to a VMS system through a terminal server such as one of the DECserver family. Programming DEC (and its successor companies) provided a wide variety of programming languages for VMS. Officially supported languages on VMS, either current or historical, include: VAX MACRO BLISS C DCL Fortran Pascal COBOL BASIC C++ Java Common Lisp APL Ada PL/I DIBOL CORAL OPS5 RPG II MUMPS MACRO-11 DECTPU VAX SCAN Among OpenVMS's notable features is the Common Language Environment, a strictly defined standard that specifies calling conventions for functions and routines, including use of stacks, registers, etc., independent of programming language. Because of this, it is possible to call a routine written in one language (for example, Fortran) from another (for example, COBOL), without needing to know the implementation details of the target language. OpenVMS itself is implemented in a variety of different languages and the common language environment and calling standard supports freely mixing these languages. DEC created a tool named the Structure Definition Language (SDL), which allowed data type definitions to be generated for different languages from a common definition. Development Tools DEC provided a collection of software development tools in a layered product named DECset (originally named VAXset). This consisted of the Language-Sensitive Editor (LSE), a version control system (the Code Management System or CMS), a build tool (the Module Management System or MMS), a static analyzer (the Source Code Analyzer or SCA), a profiler (the Performance and Coverage Analyzer or PCA) as well as a test manager (the Digital Test Manager or DTM). In addition, a number of text editors are included in the operating system, including EDT, EVE and TECO. The OpenVMS Debugger supports all DEC compilers and many third party languages. It allows breakpoints, watchpoints and interactive runtime program debugging either using a command line or graphical user interface. A pair of lower-level debuggers, named DELTA and XDELTA, can be used to debug privileged code in additional to normal application code. In 2019, VSI released an officially-supported Integrated Development Environment for VMS based on Visual Studio Code. This allows VMS applications to be developed and debugged remotely from a Microsoft Windows, macOS or Linux workstation. Database management DEC created a number of optional database products for VMS, some of which were marketed as the VAX Information Architecture family. These products included: Rdb – A relational database system which originally used the proprietary Relational Data Operator (RDO) query interface, but later gained SQL support. DBMS – A database management system which uses the CODASYL network model and Data Manipulation Language (DML). Digital Standard MUMPS (DSM) – an integrated programming language and key-value database. Common Data Dictionary (CDD) – a central database schema repository, which allowed schemas to be shared between different applications, and data definitions to be generated for different programming languages. DATATRIEVE – a query and reporting tool which could access data from RMS files as well as Rdb and DBMS databases. Application Control Management System (ACMS) – A transaction processing monitor, which allows applications to be created using a high-level Task Description Language (TDL). Individual steps of a transaction can be implemented using DCL commands, or Common Language Environment procedures. User interfaces can be implemented using TDMS, DECforms or Digital's ALL-IN-1 office automation product. RALLY, DECadmire – Fourth-generation programming languages (4GLs) for generating database-backed applications. DECadmire featured integration with ACMS, and later provided support for generating Visual Basic client-server applications for Windows PCs. In 1994, DEC sold Rdb, DBMS and CDD to Oracle, where they remain under active development. In 1995, DEC sold DSM to InterSystems, who renamed it Open M, and eventually replaced it with their Caché product. Examples of third-party database management systems for OpenVMS include MariaDB, Mimer SQL and System 1032. User interfaces VMS was originally designed to be used and managed interactively using DEC's text-based video terminals such as the VT100, or hardcopy terminals such as the DECwriter series. Since the introduction of the VAXstation line in 1984, VMS has optionally supported graphical user interfaces for use with workstations or X terminals such as the VT1000 series. Text-based user interfaces The DIGITAL Command Language (DCL), has served as the primary command language interpreter (CLI) of OpenVMS since the first release. Other official CLIs available for VMS include the RSX-11 MCR (VAX only), and various Unix shells. DEC provided tools for creating text-based user interface applications – the Form Management System (FMS) and Terminal Data Management System (TDMS), later succeeded by DECforms. A lower level interface named Screen Management Services (SMG$), comparable to Unix curses, also exists. Graphical user interfaces Over the years, VMS has gone through a number of different GUI toolkits and interfaces: The original graphical user interface for VMS was a proprietary windowing system known as the VMS Workstation Software (VWS), which was first released for the VAXstation I in 1984. It exposed an API called the User Interface Services (UIS). It ran on a limited selection of VAX hardware. In 1989, DEC replaced VWS with a new X11-based windowing system named DECwindows. It was first included in VAX/VMS V5.1. Early versions of DECwindows featured an interface built on top of a proprietary toolkit named the X User Interface (XUI). A layered product named UISX was provided to allow VWS/UIS applications to run on top of DECwindows. Parts of XUI were subsequently used by the Open Software Foundation as the foundation of the Motif toolkit. In 1991, DEC replaced XUI with the Motif toolkit, creating DECwindows Motif. As a result, the Motif Window Manager became the default DECwindows interface in OpenVMS V6.0, although the XUI window manager remained as an option. In 1996, as part of OpenVMS V7.1, DEC released the New Desktop interface for DECwindows Motif, based on the Common Desktop Environment (CDE). On Alpha and Itanium systems, it is still possible to select the older MWM-based UI (referred to as the "DECwindows Desktop") at login time. The New Desktop was never ported to the VAX releases of OpenVMS. Versions of VMS running on DEC Alpha workstations in the 1990s supported OpenGL and Accelerated Graphics Port (AGP) graphics adapters. VMS also provides support for older graphics standards such as GKS and PHIGS. Modern versions of DECwindows are based on X.Org Server. Security OpenVMS provides various security features and mechanisms, including security identifiers, resource identifiers, subsystem identifiers, ACLs, intrusion detection and detailed security auditing and alarms. Specific versions evaluated at Trusted Computer System Evaluation Criteria Class C2 and, with the SEVMS security enhanced release at Class B1. OpenVMS also holds an ITSEC E3 rating (see NCSC and Common Criteria). Passwords are hashed using the Purdy Polynomial. Vulnerabilities Early versions of VMS included a number of privileged user accounts (including SYSTEM, FIELD, SYSTEST and DECNET) with default passwords which were often left unchanged by system managers. A number of computer worms for VMS including the WANK worm and the Father Christmas worm exploited these default passwords to gain access to nodes on DECnet networks. This issue was also described by Clifford Stoll in The Cuckoo's Egg as a means by which Markus Hess gained unauthorized access to VAX/VMS systems. In V5.0, the default passwords were removed, and it became mandatory to provide passwords for these accounts during system setup. A 33-year-old vulnerability in VMS on VAX and Alpha was discovered in 2017 and assigned the CVE ID . On the affected platforms, this vulnerability allowed an attacker with access to the DCL command line to carry out a privilege escalation attack. The vulnerability relies on exploiting a buffer overflow bug in the DCL command processing code, the ability for a user to interrupt a running image (program executable) with and return to the DCL prompt, and the fact that DCL retains the privileges of the interrupted image. The buffer overflow bug allowed shellcode to be executed with the privileges of an interrupted image. This could be used in conjunction with an image installed with higher privileges than the attacker's account to bypass system security. Cross platform compatibility VAX/VMS originally included an RSX-11M compatibility layer named the RSX Application Migration Executive (RSX AME) which allowed user mode RSX-11M software to be run unmodified on top of VMS. This relied on the PDP-11 compatibility mode implemented in the VAX-11 processors. The RSX AME played an important role on early versions of VAX/VMS, which used re-used certain RSX-11M user space utilities before native VAX versions had been developed. This was discontinued in VAX/VMS V3.0 when all compatibility mode utilities were replaced with native implementations. In VAX/VMS V4.0, RSX AME was removed from the base system, and replaced with an optional layered product named VAX-11 RSX, which relied on software emulation to run PDP-11 code on newer VAX processors. A VAX port of the RTEM compatibility layer for RT-11 applications was also available from DEC. Various official Unix and POSIX compatibility layers were created for VMS. The first of which was DEC/Shell - which was a layered product consisting of ports of the Version 7 Unix Bourne shell and several other Unix utilities to VAX/VMS. In 1992, DEC released the POSIX for OpenVMS layered product, which included a shell based on the Korn Shell. POSIX for OpenVMS was later replaced by the open source GNV (GNU's not VMS) project, which was first included in OpenVMS media in 2002. Amongst other GNU tools, GNV includes a port of the Bash shell to VMS. Examples of third party Unix compatibility layers for VMS include Eunice. DEC licensed SoftPC (and later SoftWindows), and sold it as a layered product for both the VAX and Alpha architectures, allowing Windows and DOS applications to run on top of VMS. Hobbyist programs In 1997 OpenVMS and a number of layered products were made available free of charge for hobbyist, non-commercial use as part of the OpenVMS Hobbyist Program. Since then, several companies producing OpenVMS software have made their products available under the same terms, such as Process Software. Prior to the x86-64 port, the age and cost of hardware capable of running OpenVMS made emulators such as SIMH a common choice for hobbyist installations. In March 2020, HPE announced the end of the OpenVMS Hobbyist Program. This was followed by VSI's announcement of the Community License Program (CLP) in April 2020, which was intended as a replacement for the HPE Hobbyist Program. The CLP was launched in July 2020, and provides licenses for VSI OpenVMS releases on Alpha and Integrity systems. OpenVMS x86-64 licenses will be made available when a stable version is released for this architecture. OpenVMS for VAX is not covered by the CLP, since there are no VSI releases of OpenVMS VAX, and the old versions are still owned by HPE. Open source applications There are a number of community projects to port open source software to VMS, including VMS-Ports and GNV (GNU's Not VMS). Some of the open source applications which have been ported to OpenVMS, both by community groups and the developers of VMS, include: Samba Apache HTTP Server Apache Tomcat Info-Zip GNU Privacy Guard Perl Python Ruby Lua PHP git Subversion MariaDB Apache ActiveMQ OpenSSL Redis ZeroMQ SWIG Wget cURL OpenJDK Apache Axis Scala Gearman Memcached Firefox Xpdf Erlang RabbitMQ OpenSSH Influence During the 1980s, the MICA operating system for the PRISM architecture was intended to be the eventual successor to VMS. MICA was designed to maintain backwards compatibility with VMS applications while also supporting Ultrix applications on top of the same kernel. MICA was ultimately cancelled along with the rest of the PRISM platform, leading Dave Cutler to leave DEC for Microsoft. At Microsoft, Cutler led the creation of the Windows NT operating system, which was heavily inspired by the architecture of MICA. As a result, VMS is considered an ancestor of Windows NT, together with RSX-11, VAXELN and MICA, and many similarities exist between VMS and NT. This lineage is made clear in Cutler's foreword to "Inside Windows NT" by Helen Custer. A now-defunct project named FreeVMS attempted to develop an open source operating system following VMS conventions. FreeVMS was built on top of the L4 microkernel and supported the x86-64 architecture. Prior work investigating the implementation of VMS using a microkernel-based architecture had previously been undertaken as a prototyping exercise by DEC employees with assistance from Carnegie Mellon University using the Mach 3.0 microkernel ported to VAXstation 3100 hardware, adopting a multiserver architectural model. An unofficial derivative of VAX/VMS named MOS VP () was created in the Soviet Union during the 1980s for the SM 1700 line of VAX clone hardware. The main difference between MOS VP and the official DEC releases was the translation of commands, messages and documentation into Russian, and support for the Cyrillic script using KOI-8 encoding. Similarly modified derivatives of MicroVMS known as MicroMOS VP () or MOS-32M () were also created. Release history See also Comparison of operating systems Terry Shannon Event flag References Further reading Getting Started with OpenVMS, Michael D. Duffy, Introduction to OpenVMS, 5th Edition, Lesley Ogilvie Rice, OpenVMS Alpha Internals and Data Structures: Memory Management, Ruth Goldenberg, OpenVMS Alpha Internals and Data Structures : Scheduling and Process Control : Version 7.0, Ruth Goldenberg, Saro Saravanan, Denise Dumas, VAX/VMS Internals and Data Structures: Version 5.2 ("IDSM"), Ruth Goldenberg, Saro Saravanan, Denise Dumas, Writing Real Programs in DCL, second edition, Stephen Hoffman, Paul Anagnostopoulos, Writing OpenVMS Alpha Device Drivers in C, Margie Sherlock, Leonard Szubowicz, OpenVMS Performance Management, Joginder Sethi, Getting Started with OpenVMS System Management, 2nd Edition, David Donald Miller, Stephen Hoffman, Lawrence Baldwin, The OpenVMS User's Guide, Second Edition, Patrick Holmay, Using DECwindows Motif for OpenVMS, Margie Sherlock, The hitchhiker's guide to VMS : an unsupported-undocumented-can-go-away-at-any-time feature of VMS, Bruce Ellis, External links VMS Software: Current Roadmap and Future Releases VMS Software: Documentation Hoffmanlabs.org HP OpenVMS FAQ comp.os.vms Usenet group, archives on Google Groups OpenVMS OpenVMS software 1977 software Cluster computing High-availability cluster computing Fault-tolerant computer systems Digital Equipment Corporation DEC operating systems HP software Compaq software Parallel computing X86-64 operating systems Proprietary operating systems Time-sharing operating systems

Operating System (OS)

Spring (operating system) Spring is a discontinued project in building an experimental microkernel-based object-oriented operating system (OS) developed at Sun Microsystems in the early 1990s. Using technology substantially similar to concepts developed in the Mach kernel, Spring concentrated on providing a richer programming environment supporting multiple inheritance and other features. Spring was also more cleanly separated from the operating systems it would host, divorcing it from its Unix roots and even allowing several OSes to be run at the same time. Development faded out in the mid-1990s, but several ideas and some code from the project was later re-used in the Java programming language libraries and the Solaris operating system. History Spring started in a roundabout fashion in 1987, as part of Sun and AT&T's collaboration to create a merged UNIX. Both companies decided it was also a good opportunity to "reimplement UNIX in an object-oriented fashion". However, after only a few meetings, this part of the project died. Sun decided to keep their team together and instead explore a system on the leading edge. Along with combining Unix flavours, the new system would also be able to run almost any other system, and in a distributed fashion. The system was first running in a "complete" fashion in 1993, and produced a series of research papers. In 1994, a "research quality" release was made under a non-commercial license, but it is unclear how widely this was used. The team broke up and moved to other projects within Sun, using some of the Spring concepts on a variety of other projects. Background The Spring project began soon after the release of Mach 3. In earlier versions Mach was simply a modified version of existing BSD kernels, but in Mach 3 the Unix services were separated out and run as a user-space program like any other, a concept Mach referred to as a server. Data which would normally be private in the kernel under a traditional Unix system was now passed between the servers and user programs using an inter-process communication (IPC) system, ending in ports which both programs held. Mach implemented these ports in the kernel, using virtual memory to move data from program to program, relying on the memory management unit (MMU) and the copy on write algorithm to do so with reasonable performance. In its ultimate development, an OS on Mach would consist of a number of such servers, each handling a specific task. Examples would include the file system or network stack. The operating system server in such a system would be quite small, providing services unique to that OS, and forwarding most other calls to other servers. Since the OS was running on top of single set of common servers, several OS servers could be run at the same time, allowing a single system to "natively" support DOS, Unix and other operating systems at the same time. This capability was particularly exciting to companies like IBM, who were already supporting several different systems, and saw Mach as a way to combine these with common underlying code. In fact this was not so easy. Mach made several decisions at a low-level which made any system running on it Unix-like to some degree. Most notable was a security system which was modelled on fairly inflexible inherited model of Unix programs. Additionally the IPC system proved to be a major performance problem, although the nature of this issue didn't become clear until later. The performance was so poor that many commercial projects to port existing operating systems to Mach, notably IBM's Workplace OS, were eventually abandoned. Rationale Although Sun was also interested in supporting multiple operating systems, their needs were nowhere as pressing as IBM or Apple. By this point in time they had already moved platforms from their early 68k-based machines to their SPARC-based lineup, and their UNIX System V-based Solaris operating system was taking over from their BSD-based SunOS. Sun's concerns were somewhat more subtle: keeping developers interested in Sun's version of Unix; and, allowing their system to scale downwards onto smaller devices such as set-top boxes. A microkernel-based system would be particularly useful in this latter role. Spring concentrated on "programmability"; making the system easier to develop on. The primary addition in this respect was the development of a rich interface definition language (IDL), which exported interfaces with considerably more information than the one used in Mach. In addition to functions and their parameters, Spring's interfaces also included information about what errors can be raised and the namespace they belong to. Given a proper language, programs, including operating system servers, could import multiple interfaces and combine them as if they were objects native to that language — notably C++. Some time later the Spring IDL was adopted with minor changes as the CORBA IDL. Spring also explored a number of specific software advances in file systems, virtual memory and IPC performance. The result was a single Unix-like system with much better performance than Mach. Some of these changes are detailed below. Description The Sun engineers used non-standard terminology for a number of common components, which makes discussing the system somewhat confusing. For instance, Mach tasks are referred to as domains, ports as doors, and the kernel as the nucleus. The nucleus The Spring kernel was divided into two parts: a virtual memory system and the nucleus. Although the nucleus is equivalent to only one portion of the Mach kernel, the kernels of each OS are analogous enough to be considered to perform the same function. The Spring kernel includes only the most basic functionality and state needed to support user-side applications. Primarily this includes state to maintain lists of running programs (domains) and their threads, as well as the communications links between them (doors). The Spring kernel is not multi-threaded. Normally this would preclude it from use in realtime settings, but it is not clear that is the case. Normally kernels need to be threaded in order to ensure a long-running task such as disk I/O won't tie up the system and prevent a subsequent call from being serviced in time; under Spring the kernel almost immediately hands off the vast majority of requests to the servers, so under this model it is only the servers which, in theory, need to be threaded. IPC model One major difference between Mach and Spring was the IPC system. In Mach, the system was arranged as a set of one-way asynchronous pipes (ports) between programs, a concept derived from Unix pipes. In programming, however, the most common method of communications is the procedure call, or call/return, which Mach did not support directly. Call/return semantics could only be supported via additional code in higher-level libraries based on the underlying ports mechanism, thereby adding complexity. Spring instead directly supported call/return semantics in the basic communications system. This resulted in a change of terminology from ports in Mach, to doors in Spring. Doors were known to the kernel only; programs were handed a "handle" to the door with an identifier which was unique to that program. The system worked similarly to ports for the initial message; messages sent to a door were examined by the nucleus in order to find the target application and translate the door handle, but the nucleus then recorded small amounts of information from the caller in order to be able to return data quickly. This sped up the return by about 40%. Additionally, the Mach model was asynchronous — the call would return if and when the server had data. This followed the original Unix model of pipes, which allowed other programs to run if the server was busy. However, for a call/return system this has serious drawbacks, because the task scheduler has to run to select the next program to be serviced. Hopefully this was the server the call was requesting data from, but it this was not guaranteed. Under Spring, IPC is synchronous; control is immediately passed to the server without running the scheduler, improving the round trip time in the common case when the server can immediately return. Under Mach, the virtual memory system, supported by the memory management unit (MMU), was expected to provide a lightweight solution to copying data, by simply mapping the same data in memory into the two programs. In reality this solution was not at all efficient, as many MMUs had design features which made this mapping slow or even impossible. Unlike Mach's one-size-fits-all solution to IPC, Spring used a variety of methods to physically pass data between programs. One of these, the bulk-path, was basically identical to Mach's ports and messages, but in practice the bulk-path was the least common message type. For smaller messages Spring provided the vanilla-path, which directly copied the data from one space to another, something which proved to be faster than memory mapping in the real world for less than 5k of data. The fast-pathallowed for extremely fast invocations — at least when running on SPARC-based platforms. The fast-path used a unique "half-trap" to avoid much of the context switching overhead which plagued Mach systems. Instead of saving out all of the processor state—the normal procedure in the case of a trap into the kernel—Spring only saved out the top 16 SPARC registers, a number which was defined by specific implementation details of the SPARC architecture. The other portions of the register stack were rendered invisible to the receiver using the SPARC's WIM instruction, providing some level of security. The fast-path strongly resembles a classic procedure call within a single application, which uses register windows on the SPARC, adding some MMU work to move the context from one program to another. The fast-path was only available for calls passing simple values which didn't have to be translated (no door references, for instance) with up to 16 values in total. Although this would seem to be quite limiting, the fast-path is actually used by the vast majority of calls in Spring—generally over 80% of the calls and about 60% of the returns. Returns often respond with large blocks of data, for instance, a disk block, explaining why the returns more often used the other IPC systems. On 32-bit SPARC V8 systems, a complete round-trip call using the fast-path took just over 100 instructions, making it many times faster than a typical Mach call. It remains unclear whether or not the fast-path could be implemented on other machines, so the overall performance improvement of Spring is difficult to compare with Mach, which was typically measured on IA-32 systems. Specifically, a full syscall took under 20 µs on a 486DX-50 for existing BSD Unix systems, and 114 µs under Mach. This led to a performance hit of 50% or more, and doomed most Mach projects. In contrast, Spring using the fast-path boasted an IPC time of only 11 µs on a SPARCstation 2. Virtual memory Another key area of improvement in Spring was the implementation of the virtual memory (VM) system, also part of the kernel. Virtual memory is a system which ties together the physical random-access memory (RAM) in a machine, the MMU, and the disk system to create the illusion that every program on the system has its own block of RAM equal to the maximum the machine and operating system can support. The most prevalent memory addressing model in computers and operating systems in use in the 1980s and 1990s, was 32-bit, providing access to a theoretical limit of 4 GiB of memory, but until the early 2000s, only relatively expensive computers would have that much physical RAM. The VM system creates the illusion of more by using the hard disk as a backing store, an area of much slower memory used to offload inactive portions of RAM. In traditional Unix systems VM is a part of the kernel, as are the disk and memory handlers it ties together. Under Mach the decision of where to place the VM system is not so obvious—although the kernel is in control of RAM and the MMU, the disk handlers are part of external client programs. To solve this problem Mach 3 introduced a new two-layer VM system, with control of the actual VM system in the kernel, which would then ask an external client-space pager to interact with the disk system to physically copy memory around. Unfortunately this proved to be a serious performance issue, requiring several trips in and out of the kernel (with resulting context switches along with it) as the various layers of the VM system called each other. The Spring team had the advantage of being able to examine what went wrong with the Mach model and fix it. The result was a much more cleanly separated system of address spaces in programs, mapped by the VM into various memory objects, which were in turn managed by a pager for backing store handling. When a program made a request for data the request was passed to the VM system in the kernel, which would find the appropriate pager and ask it to create and set up an appropriate memory object. In exchange the pager was passed a cache manager from the VM, which was responsible for keeping track of clean/dirty status of the local cache of that memory object. Implementation details added considerable complexity to this model, but most of this was hidden. In the end the basic system had pagers which were in charge of the memory, and address spaces which were in charge of the caches. The two had well-defined interfaces allowing them to pass commands back and forth to keep their data in sync. This split in duties led to one very real performance improvement. Since programs could share the memory objects, and microkernel systems like Spring are based on the idea of copying memory around, Spring allowed programs sharing memory in this fashion to share it in the VM system as well. Thus under Mach if a network file server is handing data to a program both programs will end up using up memory in the VM system, whereas under Spring the two would naturally share the same memory objects, as the pager implementing that memory object would simply return another handle to the same memory. Only inside the VM would they be considered different objects, and would be handled by separate cache managers. Therefore, the data would only be cached in RAM once. In theory this could lead to considerably better real-world RAM usage. Additionally, the use of external pagers with a well defined API allowed the system to be cleanly separated when this was needed. Spring also allowed programs themselves to state which pager would be best suited to their needs, including themselves, allowing Spring programs to easily implement private VM systems for known workloads. For applications like file servers, web servers and database management systems, custom VMs and file systems often lead to dramatically improved performance. Name service Most operating systems include a variety of naming services. The most basic example is a file system, in which the files are internally referred to by a "handle", a small number, while a separate directory gives the files names with which the users interact. The same kind of name/identifier dichotomy occurs many other parts of the typical Unix system; printers are named in the etc/printcap file, small numbers and strings in the environment variables, and network locations in DNS. Each of these systems provided its own names, with a custom API, making the different objects appear completely different even in concept. Other systems had attempted to add naming systems to existing Unix systems, but generally these were "covers" over the existing functionality which simply collected up all the names from these various services and presented them in one collection. Due to the fact they relied on knowing about the underlying system layout they tended to be rather inflexible, not making it easy for new services to be added. These seem to have seen little use. Only in a completely new operating system could one hope to provide a universal service. For instance, Plan 9 used the file system as a universal naming service; everything from printers to windows could be accessed by name through the file system. This is an extension of the original Unix concept, one which had slowly disappeared as more and more functionality had been added over the years. Mach did not have a naming service of any sort for its ports. This proved to be a serious problem, because programs had to know in advance what servers they had to call in order to ask the kernel to provide a port. This meant that replacing functionality was much more difficult than it should have been; a new printer server needed to sit on the same ports as the old one for instance: there would be no way to run two side by side for development. If ports were instead referred to by name, servers could sit on different ports and simply use the same name. This functionality, provided by a name server, was considered highly important under Spring. Spring's approach essentially inverted the Plan 9 system: under Spring the file system was one example of a server which used the single unified name service. The same service could be used to name files on disk, environment variables, hardware devices, programs and even objects inside programs. The system was hierarchical, only the system namespace was directly supported, by a server which started at boot time. Other servers would then "bind" the names they knew into the system, the printer server would produce a list of printers, the file system would bind in the directories of attached disks. In this way a mapping of all the objects on the system was built up, potentially at runtime, and could be accessed in a file-like fashion very similar to Plan 9. All of these could be accessed using a single API, although the system also provided a variety of stub libraries to make it appear as classical services as well, notably in the Unix emulation server. The name service was also the central location for security and permissioning. Since doors, the real accessors in Spring, were handed out by the name service, the server included a complete access control list-based permission checking system. So in addition to providing permissions on the file system, under Spring any object could be controlled using the same set of permissions and user interface. Contrast this with Windows NT for instance, which includes about a dozen permissioning systems (file system, DCOM, SQL access, IIS, etc.), all of which have to be set up separately. In order to improve performance, the system included the concept of trust, allowing nameservers to assume requests from other servers were valid. For instance, if a user asked the file server to access a file, the system nameserver would pass along the request to the file system, which would immediately honor it. However, since the user was not known, the ACL's would be check against the file being accessed. Groups of related names were known as contexts. Contexts were also names, and thus similar to the file system concept of a directory. Users could build their own contexts out of seemingly unrelated objects; printers using completely separate drivers (servers) could be collected into a single list, a file could have different names in different places (or for different users), or a single domain could be built up containing every personal file in it for searching purposes. In this manner Spring allowed file directories to be "unioned", a useful feature lacking from traditional Unixen. Spring did not include a built-in object persistence system, but the name service was persistent and could be used to find objects in this sort of manner. To some degree the series of servers started during boot time provided a persistent name space which survived boots, as they copied their names into the same server. In theory the system could allow the name server to provide a "lazy launch" system, not starting the networking server until someone requests it for instance, but it does not appear it included this functionality. In fact the separation of name spaces would allow this to be separated out to the service which actually implemented the naming of doors, making implementation considerably easier. File system As stated earlier, the Spring VM allowed any program to define what pager it should use. Additionally the Spring system was based on a single universal naming system. These two concepts were combined to produce the Spring file system. Key to the Spring file system's operation was tight integration with the VM system. Since it was "known" that the VM system would be managing the local cache of the data from the file system, the file system was reduced to a command structure only, and was its own pager. That is, the file system was responsible for loading and saving data from memory objects when needed, but caching of that data would be handled for it by the VM. As mentioned before, this means that under Spring a file only exists in RAM in one place, no matter how it is being shared by the programs in the system. Spring used two sorts of file systems, a local file system which was similar to most common Unix systems, as well as a caching file system for network devices. The caching system demonstrates the utility of Spring's VM/pager split, using the same physical memory from the VM which it would have to use normally, the CFS short-circuited all read requests to the local cache, and did lazy write-backs every 30 seconds to the source file system. This would be particularly notable if common Unix directories were being loaded over the network, the normal setup for labs of workstations. Most Unix systems use similar caching mechanisms for the same performance reasons, but would end up using RAM twice, once in the cache, and again in the programs using it. The CFS also cached names from the remote system, making the initial directory traversal and open requests much faster. The Spring file system is also a name service context provider, lazily mapping directories from the on-disk structure into new contexts in the name service. These could then be accessed using the universal naming API, or alternately via a Unix emulation library which presented them as a traditional unix file system. Note that Spring's use of the term file system is somewhat confusing. In normal usage the term refers to a particular way to physically store files on a disk. Unix emulation Spring also needed to support existing Unix applications, the basis of Sun's business. To do this, Spring also shipped with two key extensions: a Unix process server which mimicked a full Unix, and a re-write of the standard libc library called libue which redirected Unix kernel requests to various servers. For instance, a Unix application which required file or network services would be directed to the associated Spring server, while one which wanted to list the currently running programs would be directed to the Unix process server. The process server was also responsible for handling signals, a concept which had no analog under Spring – nor was it really needed other than for backward compatibility, since signals are essentially an inflexible single-purpose IPC mechanism. Running a Unix application under Spring required that it be re-linked against libue; the system shipped with the majority of basic Unix utilities and an X11 server relinked and ready to use. However this method of compatibility was neither invisible nor guaranteed to work; Spring documents note that "many" applications will run unmodified (presumably other than relinking), but fail to mention what sort of problem areas the developer should expect if they do not. Subcontracts Although not directly related to Spring per se, the Sun engineers working on the project found that existing mechanisms for supporting different flavors of calls were not well defined. In order to provide a richer interface, they developed the concepts of subcontracts. Other systems Sun has added a "Unixified" version of Doors to Solaris. In the years since the Spring system work ended, work on operating systems in general has essentially ended. With the market quickly stratifying into a world dominated by Windows and Unix-like operating systems, there appear to be only niche markets open for any other system. Additionally, the poor performance of Mach 3 seems to have taken the wind out of the sails of many projects. Nevertheless, there have been some newer systems. One in particular, the L4 microkernel, shares many features with Spring's kernel. In particular it also uses a synchronous call/return system for IPC, and has a similar VM model. L4 has, so far, concentrated almost solely on the kernel itself; there is nothing analogous to Spring's naming service, security model, or file system. References An Overview of the Spring System (PDF) The Spring Nucleus: A Microkernel for Objects (PDF) The Spring Name Service (PostScript) The Spring Virtual Memory System (PDF) Microkernels Microkernel-based operating systems Object-oriented operating systems Proprietary operating systems Sun Microsystems software 1993 software

Operating System (OS)

Cromemco DOS Cromemco DOS or CDOS (an abbreviation for Cromemco Disk Operating System) is a CP/M-like operating system by Cromemco designed to allow users of Cromemco microcomputer systems to create and manipulate disk files using symbolic names. Overview CDOS was written in Zilog Z80 machine code. Due to the number of available programs available to run under Digital Research CP/M at that time, CDOS was designed to be upwards CP/M-compatible. Many programs written for CP/M versions up to and including version 1.33 run without modification under CDOS. However, programs written for CDOS generally do not run under CP/M. The Cromemco Z-2 had the ability to run Cromemco DOS. Besides CP/M 2.2 and Cromix, the Cromemco System One can also run Cromemco DOS. The Cromemco C-10 personal computer, introduced in 1982, also ran CDOS. An emulator for a Cromemco CDOS system exists. Commands The following list of commands are supported by Cromemco DOS. Intrinsic commands BYE DIR ERA REN SAVE TYPE Later versions also support the ATTR command. Extrinsic command programs @ (Batch) DUMP EDIT INIT (Initialize) STAT (Disk Status) WRTSYS (Write System) XFER (Transfer) Later versions also support the MEMTEST command. See also Harry Garland Roger Melen References External links x:\static\S100\cromemco\CDOS Discontinued operating systems Disk operating systems Microcomputer software Proprietary operating systems Cromemco

Operating System (OS)

Stratus VOS Stratus VOS (Virtual Operating System) is a proprietary operating system running on Stratus Technologies fault-tolerant computer systems. VOS is available on Stratus's ftServer and Continuum platforms. VOS customers use it to support high-volume transaction processing applications which require continuous availability. VOS is notable for being one of the few operating systems which run on fully lockstepped hardware. During the 1980s, an IBM version of Stratus VOS existed and was called the System/88 Operating System. History VOS was designed from its inception as a high-security transaction-processing environment tailored to fault-tolerant hardware. It incorporates much of the design experience that came out of the MIT/Bell-Laboratories/General-Electric (later Honeywell) Multics project. In 1984, Stratus added a UNIX System V implementation called Unix System Facilities (USF) to VOS, integrating Unix and VOS at the kernel level. In recent years, Stratus has added POSIX-compliance, and many open source packages can run on VOS. Like competing proprietary operating systems, VOS has seen its market share shrink steadily in the 1990s and early 2000s. Development Programming for VOS VOS provides compilers for PL/I, COBOL, Pascal, FORTRAN, C (with the VOS C and GCC compilers), and C++ (also GCC). Each of these programming languages can make VOS system calls (e.g. s$seq_read to read a record from a file), and has extensions to support varying-length strings in PL/I style. Developers typically code in their favourite VOS text editor, or offline, before compiling on the system; there are no VOS IDE applications. In its history, Stratus has offered hardware platforms based on the Motorola 68000 microprocessor family ("FT" and "XA" series), the Intel i860 microprocessor family ("XA/R" series), the HP PA-RISC processor family ("Continuum" series), and the Intel Xeon x86 processor family ("V Series"). All versions of VOS offer compilers targeted at the native instruction set, and some versions of VOS offer cross-compilers. Stratus added support for the POSIX API in VOS Release 14.3 (on Continuum), and added support for the GNU C/C++ compiler, GNU gdb debugger, and many POSIX commands in VOS Release 14.4. Each additional release of VOS has added more POSIX.1 capabilities, to the point where many user-mode open-source packages can now be successfully built. For this reason, beginning with Release 17.0, Stratus renamed VOS to OpenVOS. Stratus offers supported ports of Samba, OpenSSL, OpenSSH, GNU Privacy Guard, OpenLDAP, Berkeley DB, MySQL Community Server, Apache, IBM WebSphere MQ, and the community edition of Java. Numeric values in VOS are always big endian, regardless of the endianness of the underlying hardware platform. On little endian servers with x86 processors, the compilers do a byte swap before reading or writing values to memory to transform the data to or from the native little endian format. Command Macro Language VOS has a fairly complete command macro language which can be used to create menu systems, automate tasks etc. VOS command macros accept arguments on the command-line or via a user interface "form". Arguments are defined at the beginning of the command macro in a "parameters" section. The language supports a range of statements, including if/then/else, boolean operations, "while" loops, "goto" and excellent error reporting. The command macro language can be executed in interactive and non-interactive (batch or started process) modes. It can be used to automate programs, capturing prompts and sending appropriate responses. This has led Stratus to limit the capabilities of the command macro language. The macro language lacks support for user-defined functions and does not easily support include files. The string handling is prone to errors, especially with embedded control characters. Overview VOS was coded mainly in PL/I with a small amount of assembly language before it was migrated to ftServer series. As of 1991, the system was written in PL/I and C, with only 3% in assembly. Its overall structure has much in common with Multics, and many of the system's features can be traced back to Multics to varying degrees. The system exposes a number of fundamental abstractions to the software designer or programmer, most notable being Processes Devices Hard Disks Various IPC mechanisms Tasks A process is the scheduled entity in VOS and each process has a set of attributes that govern how it is manipulated by the system. For example, processes have a user name and process name. The former is used by VOS to determine the process's access rights to external devices and items with the file system. Of fundamental significance is a process's privileged flag, which is a binary attribute. Privileged processes may perform privileged operations. This mechanism is used to restrict certain potentially powerful operations that can have system wide consequences (e.g. shutting down the system, dismounting a hard disk etc.). Distribution VOS is distributed only by Stratus Technologies. The distribution media is a 3.5 mm DAT tape for Continuum, and an SDLT tape for early V Series platforms. As of OpenVOS Release 17.0, Stratus offers support for distributing OpenVOS on a DVD or by downloading a release file. Software installations may be done by the Stratus Field Engineer or by the customer's system administrator. Interface The command-line interface is the main, and most powerful, user interface for a VOS system. Users may be locked into "form" based sub-system by command macro scripts if required, although a skilled user would be able to break out of this and get command-line access. (It is, in fact, possible for a Stratus system administrator to set up a user's account such that an attempt to break out of FMS—the Stratus Forms Management System—to the command line results in the user being logged out.) Command macros and programs can be invoked with an argument to display a form listing all the available parameters, which the user can navigate using the "tab" key. Each parameter is generally restricted to control what the user can input. This includes lists of valid values, numeric-only, text-only, etc. Parameters can also be hidden using a "secret" tag, or made mandatory. All commands in VOS are defined in full with underbars to separate words. For example, changes the working directory. The VOS help system uses this convention to assist users who are looking for a subset of possible commands; for instance, those referring to "change" are found by . Users may customize their command interface by means of a file that contains abbreviations for commands. Command abbreviations are conventionally named after the first letters of the command they represent, so may be expanded to . Applications System applications VOS is used on Continuum and ftServer systems, both of which are designed to be highly fault-tolerant. As such, these systems are typically used in safety-critical or mission-critical applications, typically banks, hospitals, telecommunications and transaction processing companies. Communications VOS supports the following protocols TCP/IP X.25 SNA SDLC/QLLC Async Bisync LAPB Poll/Select RJE/HASP ALC/SLC Visa, S.W.I.F.T., NASDAQ, FAS, CHIPS, AMEX MQ Series Older versions of VOS implemented a non-OSI standard TCP/IP known as OS TCP/IP (Operating System TCP/IP.) VOS since version 14.x has implemented OSI-compliant Streams-TCP. Older applications using OS TCP/IP have to be ported in order to use STCP. This can mean a loss of functionality as OS TCP/IP supported several functions that are not OSI-compliant and have therefore been abandoned. The ftServer hardware that V Series runs on only supports TCP/IP and X.25 (X.25 only when equipped with the optional NIO.) Websphere MQ 6.0 (a.k.a. MQ Series) is TCP/IP based; so, that is also supported by ftServer hardware. Devices supporting the legacy protocols run on the Continuum hardware and may be accessed from current hardware over the Open StrataLINK network. Fault tolerance Fault tolerance is built into VOS from the bottom up. On a hardware level, major devices are run in lockstepped duplex mode, meaning that there are two identical devices performing the same action at the same time. (In addition, each device, or board, is also duplexed in order to identify internal board failures at a hardware level, which is why Stratus hardware can be defined as "lock stepped".) These boards are actively monitored by the operating system which can correct any minor inconsistencies (such as bad disk-writes or reads). Any boards which report an unacceptable number of faults are removed from service by the system; the duplexed board will continue operation until the problem is resolved via a hot-fix. This includes CPUs, disk drives, and any other device that can logically be duplexed (which by definition, excludes communications devices). The system will continue processing as normal and will automatically raise a fault ticket with Stratus Customer Service via RSN (the Remote Service Network). Stratus Customer Service will then dial into the system using RSN to investigate the problem and dispatch replacement parts. The operating system is designed to avoid crashes due to a simplexed hardware failure. File system VOS supports a number of unique file types: Stream files: a stream of binary data, corresponding directly with the concept of a file on other operating systems. Fixed files: a sequence of records of a fixed size. Relative files: a sequence of records of a fixed file supporting random access Sequential files: a sequence of records of variable size Queue files: file-system based backup for message queues Pipes: named pipes for inter-process communication Transaction files: these provide support for journal based rollback The VOS API allows the creation of multiple indexes per file, sorting according to the contents of a record, or an external key, or an internal key, or a well-defined set of multiple keys. A VOS file with one or more indexes can be used as a C-ISAM database table. VOS uses a proprietary file naming syntax which includes the system name, module name, disk number, and directory, with components separated by the ">" symbol. Typically the system disk will be housed in the same module as the CPU, #m1, so a system file for a VOS cluster would be referenced as (%system)#m1_d01>system>devices.table VOS disk allocation and memory is organised in "blocks", each block being 4,096 bytes. Memory takes the form of RAM or paging. VOS systems support paging partitions and paging files. In modern versions of VOS, paging files can be created dynamically by the SysAdmin (but not removed without a reboot). These paging files can in theory consist of more than one extent (which is viewed by the kernel as a mini-paging partition) which may or may not be contiguous. However, non-contiguous extents are NOT recommended as they greatly increase disk activity. Admin should create the largest possible extent for the paging files as early as possible after the system has been booted. File system security VOS supports write, read, execute, and null (no) access to all files, directories and devices (although directories and files have slightly different access lists). Access can be assigned to users, groups, or the world. Only read access is required to run an executable program, provided that the user has "status" access for the directory in which that program resides. VOS inherited access control lists from Multics and also implements directory access control lists. If a file does not have an access control list, the containing directory's default access control list applies. Access to devices is typically controlled by creating a file which is linked to the device by the administrator. (This may be true in OpenVOS, but does not apply to the original operating system.) Access is then given to this file, and this sets the access on the device. Open StrataLINK VOS has always been a network-aware operating system. Virtually every system call in the native API has a parameter that determines what computer the operation affects. If the operation isn't local, it is redirected to the target computer via remote subroutine call. For example, file names are parsed to indicate which computer the file resides on. The StrataLINK networking model has a two level hierarchy for naming computers: Each computer is called a module and modules are aggregated into systems. Each system is administered as a unit. In other words, all of the modules in a system are aware of all the disks and hardware devices on that system. The result of this is that a file name that begins with the system name refers to files on other computers and can be opened without the need for any special networking. The same is true for devices. Other system entities, such as processes, are referenced using module names which are written %system#module. The VOS system and module names have no defined relationship with IP addresses or domain names—The VOS API was developed in late 1980—before the Internet was widely adopted and long before URLs were even invented. Historically, StrataLINK was a proprietary 10Mb CSMA/CD ring network which allowed high performance (for the time) with very low memory overhead and CPU utilization. This was never developed beyond 10Mb and was dropped in favor of using TCP/IP because Ethernet became the dominant networking standard and because memory and CPU processing got cheaper. Open StrataLINK can also use X.25 for wide area communications. Using the Open StrataLINK protocols for wide area communications is also referred to as StrataNET. See also Comparison of command shells Tandem Computers References External links Official OpenVOS website Comp.Sys.Stratus Stratus Public FTP Server Stratus Documentation Site Proprietary operating systems Fault-tolerant computer systems Multics-like

Operating System (OS)

SUSE Linux Enterprise SUSE Linux Enterprise (often abbreviated to SLE) is a Linux-based operating system developed by SUSE. It is available in two editions, suffixed with Server (SLES) for servers and mainframes, and Desktop (SLED) for workstations and desktop computers. Its major versions are released at an interval of 3–4 years, while minor versions (called "Service Packs") are released about every 12 months. SUSE Linux Enterprise products receive more intense testing than the upstream openSUSE community product, with the intention that only mature, stable versions of the included components will make it through to the released enterprise product. It is developed from a common code base with other SUSE Linux Enterprise products. IBM's Watson was built on IBM's POWER7 systems using SLES. In March 2018, SUSE Product Manager Jay Kruemcke wrote in SUSE blog that SUSE Linux Enterprise developers have ported it to Raspberry Pi. SUSE Linux Enterprise Server SLES was developed based on SUSE Linux by a small team led by Marcus Kraft and Bernhard Kaindl as principal developer who were supported by Joachim "Jos" Schröder. It was first released on October 31, 2000 as a version for IBM S/390 mainframe machines. In December 2000, the first enterprise client (Telia) was made public. In April 2001, the first SLES for x86 was released. From a business perspective, SLES is not only a technical offering, but also has entangled a commercial offering (services and support). The initial business model was inspired by recurrent charges established in the mainframe world at this time, and innovated by Jürgen Geck and Malcom Yates. Based on customer needs and feedback as well as other evolving Linux based offerings the business model has been reworked by different people in the subsequent years until today. SUSE Linux Enterprise Server 9 (SLES 9) was released in August 2004. Service Pack 4 was released in December 2007. It was supported by hardware vendors including IBM, HP, Sun Microsystems, Dell, SGI, Lenovo, and Fujitsu Siemens Computers. SUSE Linux Enterprise Server 10 (SLES 10) was released in July 2006, and is also supported by the major hardware vendors. Service pack 4 was released in April 2011. SLES 10 shared a common codebase with SUSE Linux Enterprise Desktop 10—Novell's desktop distribution for business use—and other SUSE Linux Enterprise products. SUSE Linux Enterprise Server 11 (SLES 11) was released on March 24, 2009 and included Linux kernel 2.6.27, Oracle Cluster File System Release 2, support for the OpenAIS cluster communication protocol for server and storage clustering, and Mono 2.0. SLES 11 SP1 (released May 2010) rebased the kernel version to 2.6.32. In February 2012, SLES 11 SP2 was released, based on kernel version 3.0.10. SLES 11 SP2 included a Consistent Network Device Naming feature for Dell servers. SUSE Linux Enterprise Server 12 (SLES 12) beta was made available on February 25, 2014, and the final version was released on October 27, 2014. SLES 12 SP1 was released on December 18, 2015. SP1 added Docker, Shibboleth, Network Teaming, and JeOS images. SP2 was released November 11, 2016. SP3 was released September 7, 2017. The SLES 13 and SLES 14 version numbers were skipped due to superstitions associated with those numbers in certain cultures. SUSE Linux Enterprise Server 15 (SLES 15) beta 1 was released on October 18, 2017, and the final version was released on July 16, 2018. SLES 15 SP2, which updates the kernel, PostgreSQL, Samba, Salt and many other parts of the operating system, was released on July 21, 2020. SUSE Linux Enterprise Desktop SUSE Linux Enterprise Desktop (SLED), introduced as Novell Linux Desktop (NLD), targeted at the business market, it is developed from a common codebase with SUSE Linux Enterprise Server (SLES) and other SUSE Linux Enterprise (SLE) products. SLED includes the GNOME Shell, LibreOffice, Evolution and many other popular open source packages such as Dia, TigerVNC, and lftp. Like SLES, SLED is based on openSUSE Tumbleweed and shares a common codebase with openSUSE Leap. SLED since version 12 has included a modified version of the GNOME Classic Shell to include a layout with one panel on the bottom of the screen, traditional application menus, and desktop icons for traditional desktop users. It also includes LibreOffice, Mozilla Firefox, and Evolution along with many standard GNOME utilities, such as GNOME Documents and GNOME Files. As well, the YaST Control Center allows end users to make advanced changes to the system from the command line. HP offers business notebooks with SLED 11 preinstalled, under both its own brand and the Compaq brand. Micro-Star International offered MSI Wind Netbooks with SLED 10 preinstalled. Sun Microsystems previously licensed SLED as the basis of the Linux version of Java Desktop System. History SUSE Linux Enterprise Desktop has been developed while SUSE was under the ownership of several different parent companies. SUSE was owned by and conducted business as Novell from SLED's first release as Novell Linux Desktop in 2004 until 2011 when The Attachmate Group purchased Novell and created SUSE as an autonomous subsidiary. Micro Focus in turn purchased The Attachmate Group in 2014 and made SUSE an autonomous business unit, before selling it to EQT Partners in 2019. EQT Partners is a private equity group that develops new companies before divesting them as independent companies. Novell Linux Desktop 9 Novell Linux Desktop (NLD) 9 was originally released November 8, 2004, less than a year after Novell's acquisition of SUSE. There were a number of Service Packs (SP's) released for NLD 9. SP1 was released on February 11, 2005 and contained many updates. After that, SP2 was released on August 9, 2005, containing all the released updates and bugfixes since August 2004. SP3 was released on December 22, 2005. NLD 9 was based on SUSE Linux 9.1 and offered a more conservative offering of desktop applications for businesses. Its desktop included common end user applications like Mozilla Firefox, OpenOffice.org. NLD also included software developed by Novell and its 2003 acquisition Ximian, such as the Red Carpet software management tool from Ximian and Novell's system management tool ZenWorks. SUSE Linux Enterprise Desktop 10 With SLED 10, Novell increased the focus on features for a broader range of corporate users by focusing on meeting the needs for basic office workers, positioning SLED as a competitor to Microsoft Windows. Basic office workers were defined in this context as users who need basic desktop functionality, including an office suite, a collaboration client, a web browser, and instant messaging. Novell attempts to meet these needs by concentrating on making these components very compatible with existing enterprise infrastructure, such as Microsoft Office data files, Microsoft Active Directory, and Microsoft Exchange Server or Novell GroupWise collaboration systems. It also included the Beagle desktop search tool, similar to Spotlight in Mac OS X v10.4. The Xgl+Compiz support enables a variety of advanced graphical effects in the user interface, such as "application tiling" (similar to Exposé). Other features include making it easier for Linux beginners to connect digital cameras to the computer and play audio files such as MP3s using Helix Banshee. The version of GNOME included this release was highly customized, and debuted the slab application menu on a one panel layout. SLED 10 was originally released June 17, 2006. The last service pack for SLED 10 was Service Pack 4, released April 15, 2011. SUSE Linux Enterprise Desktop 11 SLED 11, based on openSUSE 11.1, was released March 24, 2009. It included an upgrade to GNOME and was the first release to ship KDE 4, with version 4.1.3. Several improvements were made to improve Microsoft Active Directory and Microsoft Exchange Server integration, and the Novell OpenOffice.org version was upgraded to version 3.0. SLED continued to include some proprietary components such as Adobe Flash, as well as open-source implementations of closed sourced plugins and runtimes such as Moonlight and Mono. Four service packs were released for SLED 11, with Service Pack 2 notably bringing BtrFS commercial support to the enterprise Linux market and including the snapper tool to manage BtrFS snapshots. The most current service pack, SP 4, was released July 17, 2015. SUSE Linux Enterprise Desktop 12 On October 28, 2014, SUSE (now an independent business unit) released SLED 12 built on openSUSE 13.1. SLED 12 introduced several new technological upgrades, including systemd, GNOME 3, GRUB 2, plymouth, and the in-house built wicked wireless network manager. SLED 12 also included further stability and integration with BtrFS. With the transition to GNOME 3, the GNOME Classic Shell, the vanilla GNOME Shell, and a SLE Classic Shell with a design that more closely mimics the slab layout were included. KDE, the default desktop environment in openSUSE, and support for 32-bit x86 processors were dropped from the enterprise distribution. SLE 12 Service Pack 1 was the first to be the basis for openSUSE's more conservative Leap series, with openSUSE Leap 42.1 sharing its codebase with SLE 12 SP 1. Leap 42.2 and 42.3 were built from the same codebase as SLE 12 SP 2 and SLE SP 3 respectively. SLED 12's underlying base, SUSE Linux Enterprise Server 12, was the first version of SLE to be offered on the Microsoft Store to be run on the Windows Subsystem for Linux. SUSE Linux Enterprise Desktop 15 SLE skipped over versions 13 and 14, realigning the versions of openSUSE Leap and SLE at version 15. SLE 15 was released June 25, 2018 with the same codebase as openSUSE Leap 15.0. SLED 15 included major upgrades to GNOME 3.26, LibreOffice 6.0, GCC 7 and LTS kernel version 4.12. Version 15 also made the Wayland implementation of GNOME the default. SLES and SLED can now also be installed from the same media. SLED 15 offers the same GNOME Desktop options as SLED 12. SLE 15 SP 1 shares a common codebase with openSUSE Leap 15.1. SLE 15 SP 1 includes improvements to the ability to migrate from openSUSE Leap to SLE, increased 64-bit Arm System on a Chip (SoC) supported processor options, transactional updates, and various other features. SLE 15 SP 3 features a unified repository with same source code and binary packages with openSUSE Leap 15.3. People Novell's effort on SUSE Linux Enterprise Desktop 10 was led by Nat Friedman, one of the two founders of Ximian. Nat was aided by a host of former Ximian and SUSE developers, with product manager Guy Lunardi and engineering manager Kelli Frame. Derivatives Through SUSE Studio Express, users can create custom appliances based on SUSE Linux Distributions including SLED. Options for SLE allow for the creation of derivative distributions as custom Kiwi and docker containers with customized package choices and configuration parameters. Features SUSE's work on SUSE Linux Enterprise Desktop brings several unique features to its implementation of desktop enterprise Linux. Desktop Effects Desktop Effects was built upon Xgl and Compiz to enable a variety of advanced graphical effects in the user interface, such as "application tiling" (similar to Exposé) and a spinning cube that interactively switches between desktops. The now included GNOME 3 Shell includes several graphical desktop effects by default. Device and Application Support SLED also includes the ability to connect digital cameras and iPods to a computer, and have an appropriate application automatically start when this happens. YaST Control Center YaST is the primary configuration tool in the SUSE Linux distributions, including SLED. YaST is an installation and administration program which can handle hard disk partitioning, system setup, RPM package management, online updates, network and firewall configuration, user administration and more in an integrated interface consisting of various modules for each administrative task. SUSE Package Hub SUSE Package Hub gives SLE users the option to install packages that are not an official part of the SUSE Linux Enterprise distribution or are more up to date than those included with the latest version of SLE. SUSE Package Hub is unofficial, and the software installed from its repositories does not receive commercial support from SUSE. Currently about 9,000 packages are available from SUSE Package Hub for SLE 12 and 15 with packages available for AArch64, ppc64le, s390x, and x86-64. End-of-support schedule Legacy versions of SUSE Linux Enterprise (SLES 9 and 10) had a ten year product lifecycle. Newer versions have a thirteen year product lifecycle (SLES 11, 12, and 15). The current support model consists of 10 years of general support from time of First Customer Shipment (FCS), followed by 3 years of Long Term Service Pack Support (LTSS). Version history Release dates of SUSE Linux Enterprise Server versions: SuSE Linux Enterprise Server for S/390, October 31, 2000 for Sparc and IA-32, April 2001 SUSE Linux Enterprise Server 7 (For first time, common codebase for all architectures (IA-32, Itanium, iSeries and pSeries, S/390 and zSeries 31-bit, zSeries 64-bit)) Initial release, October 13, 2001 SUSE Linux Enterprise Server 8 Initial release, October 2002 SP1 SP2 SP2a SP3 SP4 SUSE Linux Enterprise Server 9 Initial release, 2004-08-03 SP1, 2005-01-19 SP2, 2005-07-07 SP3, 2005-12-22 SP4, 2007-12-12 SUSE Linux Enterprise Server 10 Initial release, 2006-06-17 SP1, 2007-06-18 SP2, 2008-05-19 SP3, 2009-10-12 SP4, 2011-04-12 SUSE Linux Enterprise Server 11 Initial release, 2009-03-24 SP1, 2010-06-02 SP2, 2012-02-15 SP3, 2013-07-01 SP4, 2015-07-16 SUSE Linux Enterprise Server 12 Initial release, 2014-10-27 SP1, 2016-01-12 SP2, 2016-11-11 SP3, 2017-09-07 SP4, 2018-12-11 SP5, 2019-12-09 SUSE Linux Enterprise Server 13 Skipped SUSE Linux Enterprise Server 14 Skipped SUSE Linux Enterprise Server 15 Initial release, 2018-07-16 SP1, 2019-06-24 SP2, 2020-07-21 SP3, 2021-06-23 See also SUSE Linux Linux on PowerPC Linux on IBM Z List of Linux distributions Comparison of Linux distributions Red Hat Enterprise Linux References Further reading Server Desktop External links SUSE Linux Enterprise Desktop product page SUSE Linux Enterprise Desktop cool solutions tips & tricks, guides, tools and other resources submitted by the SUSE Linux Enterprise community Example story of SLED 10 use in an educational environment Interview with Novell's Ted Haeger on NLD News about the next Novell Linux Desktop Novell aims rebranded SUSE Linux 10 at enterprise desktops - DesktopLinux.com news item about upcoming SUSE Linux Enterprise Desktop 10 Enterprise Linux distributions Power ISA Linux distributions RPM-based Linux distributions SUSE Linux X86-64 Linux distributions ARM Linux distributions Linux distributions Linux distributions used in appliances

Operating System (OS)

MacOS Sierra macOS Sierra (version 10.12) is the thirteenth major release of macOS (formerly known as and ), Apple Inc.'s desktop and server operating system for Macintosh computers. The name "macOS" stems from the intention to uniform the operating system's name with that of iOS, watchOS and tvOS. Sierra is named after the Sierra Nevada mountain range in California and Nevada. Its major new features concern Continuity, iCloud, and windowing, as well as support for Apple Pay and Siri. The first beta of macOS Sierra was released to developers shortly following the 2016 WWDC keynote on June 13, 2016. The first public-beta release followed on July 7, 2016. It was released to end users on September 20, 2016, as a free upgrade through the Mac App Store and it was succeeded by macOS High Sierra on September 25, 2017. System requirements macOS Sierra requires at least 2 GB of RAM and 8 GB of storage space and will run on: iMac: Late 2009 or newer MacBook and MacBook 12-inch: Late 2009 or newer MacBook Pro: Mid 2010 or newer MacBook Air: Late 2010 or newer Mac Mini: Mid 2010 or newer Mac Pro: Mid 2010 or newer Xserve is no longer compatible. Sierra is the first version of macOS since OS X Mountain Lion, released in 2012, that does not run on all computers that the previous version supported. Developers have created workarounds to install macOS Sierra on some Mac computers that are no longer officially supported as long as they are packed with a CPU that supports SSE4.1. This requires using a patch to modify the install image. Changes The default desktop picture is an image of Lone Pine Peak. System features Siri The user can access the Siri intelligent assistant via the Dock, the menu bar or a keyboard shortcut and results are shown in a window in the upper-right corner. Siri can send messages, search the web, find files and adjust settings. Results can be dropped into other applications or pinned to Notification Center. For instance, pictures from search results can be dragged into a document. iCloud Drive and Optimized Storage iCloud Drive can upload the user's documents and desktop directories and sync them to other devices. The System Information application has a new section that gives the user detailed information about space usage per application or file and provides tools and suggestions for freeing up space. For instance, the user can let the system upload old files to iCloud Drive and remove their local copies, keeping them available on-demand in Finder. It can also remove old files from trash automatically. iTunes can delete watched, purchased films and TV programs from its library. Auto Unlock and Universal Clipboard Building upon Continuity, an "umbrella term [for] features that facilitate the communication between [Apple devices]" using Bluetooth and Wi-Fi, Sierra adds two features. With Auto Unlock, the user can unlock their user account by holding a paired Apple Watch close to the device. Time of flight is used to prevent relay attacks. Auto Unlock requires a Mac that was introduced in 2013 or later. With Universal Clipboard, the user can share the clipboard for cut, copy and paste between macOS Sierra and iOS 10 devices, including text and rich content, such as pictures or videos. Tabs and Picture-in-Picture Applications that support multiple windows can support multiple tabs within a single window, allowing the user to keep windows organized similarly to Safari. With Picture-in-Picture, videos can be played in a window that follows the user across the system. Apple File System Apple released a preview of a new file system in Sierra, called Apple File System (APFS), to overcome the limitations of HFS Plus. It is intended for solid-state drives and flash memory and will adopt several features found in modern file systems, such as snapshots and cloning, as well as native support for features that Apple already provides in HFS Plus through supplementary software, such as file-system encryption and TRIM support. The file system was released in macOS High Sierra. Night Shift Night Shift is new in macOS 10.12.4, with the same functionality as its iOS counterpart. Night Shift reduces blue light at night to aid sleep. This can be scheduled in the System Preferences app (in the Displays menu) and can be toggled on or off in the Notification Center or using Siri. Since this feature relies on the Metal framework, Night Shift is not available on all systems that support macOS Sierra. Application features Photos Apple says it has improved the face recognition of the Photos application, adding object and scene recognition. It groups similar pictures together using faces, locations and object recognition to create "memories". Memories contain picture slideshows with transitions and music selected by the algorithm, which can be modified to the user's liking. The "People" album organizes photos by the people in them, and Places shows all photos on a world map. Safari and Apple Pay Safari provides an "extension point" which enables developers to bundle Safari extensions within their Cocoa applications and communicate with them directly from the applications. Safari conceals the presence of installed "legacy" plug-ins, such as Adobe Flash Player, Java applets, Microsoft Silverlight, and QuickTime – from websites and requires the user to enable a specific plug-in on a per-use or per-website basis. Apple Pay allows vendors to embed an Apple Pay button on their websites. In Safari, users can click the Apple Pay button to check out, then complete a purchase using an iPhone or Apple Watch. Apple Pay requires a Mac that supports Continuity (2012 or later models) and either an iPhone 6 or later with iOS 10, or an Apple Watch with watchOS 3. Messages The Messages app adds aesthetic effects to messages, such as three times bigger emojis and click back with hearts or thumbs-up on a message bubble. The ability to play YouTube videos and preview links in a conversation was introduced. Users can view interactive content added to iMessage in iOS 10. The app also allows you to turn on or off read receipts on a conversation by conversation basis. iTunes Apple Music within iTunes has been redesigned, making it simpler to find favorite songs and discover new ones. A new "For You" tab has been added, which suggests new music the user might like (similar to the existing Genius). A refined MiniPlayer with the ability to view lyrics while listening has also been introduced. Notes The Notes app allows the user to share and collaborate on notes. This is done by clicking on a share button at the top of the window. Other changes Disk Utility regains the ability to format and manage RAID sets, after it was removed in El Capitan. Finder has an option to show folders always at the top of the view hierarchy, for instance in list views. Mail adds a control to the top of email lists to quickly filter them, for instance, by read status or the presence of attachments. 13 & 15-inch Retina MacBook Pros now default to integer scaled over nearest-neighbor scaled resolutions to fit more content. Other applications found on macOS 10.12 Sierra AirPort Utility App Store Archive Utility Audio MIDI Setup Automator Bluetooth File Exchange Boot Camp Assistant Calculator Calendar Chess ColorSync Utility) Console Contacts Dictionary Digital Color Meter DVD Player FaceTime Font Book Game Center GarageBand (may not be pre-installed) Grab Grapher iBooks (now Apple Books) iMovie (may not be pre-installed) iTunes Image Capture Ink (can only be accessed by connecting a graphics tablet to your Mac) Keychain Access Keynote (may not be pre-installed) Migration Assistant Numbers (may not be pre-installed) Pages (may not be pre-installed) Photo Booth Preview QuickTime Player Reminders Script Editor Stickies System Information Terminal TextEdit Time Machine VoiceOver Utility X11/XQuartz (may not be pre-installed) Security improvements Gatekeeper macOS Sierra slightly changes the Gatekeeper user interface and adds two new mechanisms. A new default in System Preferences hides the "Anywhere" option which allows the user to disable the mechanism and execute programs from any source without needing to approve each new one individually. The first new mechanism allows developers to code-sign disk images that can be verified as a unit by the system. This allows developers to guarantee the integrity of external files that are distributed alongside the application bundle on the same disk image. An attacker could infect these external files with malicious code and with them exploit a vulnerability in the application, without having to break the signature of the application bundle itself. By signing the disk image, the developer can prevent tampering and force an attacker to repackage the files onto a new disk image, requiring a valid developer certificate to pass Gatekeeper without a warning. The second new mechanism is "path randomization", which executes application bundles from a random, hidden path and prevents them from accessing external files relative to their location. To avoid this, the developer has to distribute the application bundle and its external files on a signed disk image or in a signed installer package. The user can avoid this mechanism by moving the application bundle without its external files to a new location. Directory permissions and sudo The Unix permissions for writing to the /Volumes directory are now restricted to root and no longer "world-writable". Apple expanded System Integrity Protection to , a directory that contains a list of applications that are allowed to "control the computer", and restricts write access to programs which were signed with an Apple "private entitlement". The file-hosting service Dropbox has been criticized for manipulating the directory to add their Dropbox application to the list, rather than asking the user to do it for them explicitly in System Preferences. The sudo command-line utility with which a user can execute a command as another user, typically as root, is configured with the "tty_tickets" flag by default, restricting the session timeout to the terminal session (such as a window or tab) in which the user authenticated the program. Removed functionality Sierra removes support for garbage collection from the Objective-C runtime, a memory-management system that was added in Mac OS X Leopard (version 10.5) and declared deprecated in favor of Automatic Reference Counting in OS X Mountain Lion (version 10.8). Applications that have been compiled with garbage collection will no longer run. Apple removed native support for the VPN protocol PPTP and made recommendations for alternatives that it considers more secure. The "time remaining" estimate has been removed in the 10.12.2 update after complaints of the battery life of 2016 MacBook Pros. The Game Center app has been removed. However, the service still exists. Reinstallation Following the download of macOS Sierra (10.12) from the Mac App Store, the installer does not show under a users' "Purchased" tab in the Mac App Store app. Users can still re-download the Sierra installer by visiting the macOS Sierra page on the Mac App Store. Reception macOS Sierra has received generally positive reviews. Users and critics have praised its functionality, including the addition of Siri and support for Apple Pay in Safari. Macworld gave it 4.5 stars out of 5. Engadget gave it a rating of 87 out of 100 praising the new features such as Siri integration, Universal Clipboard, and Apple Pay while criticizing the unreliability of Auto Unlock, that "Siri isn't always smart enough" and some of the Messages features are only available on iOS 10. Developers of apps that rely on the PDFKit library built into macOS have complained that radical changes to PDFKit introduced in Sierra are causing instability and potential data corruption. Release history References External links – official site macOS Sierra download page at Apple 12 X86-64 operating systems 2016 software Computer-related introductions in 2016

Operating System (OS)

PRIMOS PRIMOS is a discontinued operating system developed during the 1970s by Prime Computer for its minicomputer systems. It rapidly gained popularity and by the mid-1980s was a serious contender as a mainline minicomputer operating system. With the advent of PCs and the decline of the minicomputer industry, Prime was forced out of the market in the early 1990s, and by the end of 2010 the trademarks for both PRIME and PRIMOS no longer existed. Prime had also offered a customizable real-time OS called RTOS. Internals One feature of PRIMOS was that it, like UNIX, was largely written in a high level language (with callable assembly language library functions available). At first, this language was FORTRAN IV, which was an odd choice from a pure computer science standpoint: no pointers, no if-then-else, no native string type, etc. FORTRAN was, however, the language most known to engineers, and engineers were a big market for Prime in their early years. The unusual choice of FORTRAN for the OS programming language had to do with the people who founded Prime. They had worked for Honeywell on a NASA project. FORTRAN was the language they had used both at NASA and, for many of them, at MIT. Honeywell, at that time, was uninterested in minicomputers, so they left and founded Prime, "taking" the code with them. They developed hardware optimized to run FORTRAN, including machine instructions that directly implemented FORTRAN's distinctive 3-way branch operation. Since Prime's hardware did not perform byte addressing, there was no impetus to create a C compiler. Late models of the hardware were eventually modified to support I-mode, and programs compiled in C. Later, around version 18, a version of PL/1, called PL/P, became the high level language of choice within PRIMOS, and the PL/P and Modula-2 languages were used in the Kernel. Furthermore, some new PRIMOS utilities were written in SP/L, which was similar to PL/P. The source code to PRIMOS was available to customers and, thanks to FORTRAN and PL/P, customers could reasonably modify PRIMOS as needed. For example, around 1990, the University of Salford in the UK, modified the PRIMOS running on its five 9955 systems so that undergraduates could no longer use the MESSAGE command, that wrapped the PRIMOS SMSG$() call, to send messages to other undergraduates, because online "chatting" using that command was becoming rife, tying up terminals from the limited pool available. Messaging using that command was akin to SMS text messaging today, except a maximum of 80 characters could be sent per message. Very early versions of PRIMOS (revision 6) were originally called DOS (PRIMOS 2) and later DOSVM (PRIMOS 3), but starting with PRIMOS 4, on the P400 system, PRIMOS was the name that stuck. There were many major releases of PRIMOS. The last official revision (24.0.0.R52) was released July 3, 1997. By this time, a company called Peritus (which employed a number of ex-Prime engineers) was maintaining PRIMOS. From Revision 19, major portions of PRIMOS were written in the languages SPL and Modula-2, the usage of the Prime Macro Assembler _(PMA), FORTRAN IV and PL/P declined considerably around this time. Programs were guaranteed to run on all current Prime processors (subject to sufficient resources being available), as well as all subsequent Prime processors. In the versions of PRIMOS ca. 1977 and later, the filesystem included a distinctive construct known as the Segment Directory. Unlike more traditional directories, the files anchored in a segment directory were located using an integer index, effectively reducing searches of the directory to a simple hash function. Segment Directories were used in their Keyed-Index/Direct Access (KI/DA) file access system and in later versions of the system loader. Data access Indexed data could be stored in a MIDAS file: Multi-Indexed Data Access System and be accessed via COBOL or FORTRAN. Among the third party tools was a package named Queo, which was more powerful than COBOL despite being less verbose. The PRIMOS character set was basically ASCII but with the 8th bit inverted. The original 7-bit standard for ASCII left the 8th bit unspecified, but on the commonly available Teletype Model 33 ASR, the bit was customarily set to 1, and this became Prime's standard. This is vital to realize when transferring data from PRIMOS to almost any other system. User tools By the time of Prime Computer's demise, a list of languages supported by Primos included: Also available, but relatively uncommon, were: DBASIC Interpreted BASIC with double-precision arithmetic RPG Compiles an RPG II program (non-virtual) SPL Compiles an SPL program VRPG Compiles an RPG II program (virtual) Scripting Late versions of PRIMOS included a scripting language, CPL (Command Processing Language) that ESRI used as a basis for its platform-independent scripting languages AML (for ArcInfo) and SML (PC-ARC/INFO). This was a step beyond what already was available via: COMI Command input (.COMI filetype) COMO Command output similar to a batch log file, but also usable interactively PHANTOMS vs JOBS "Phantoms" were a form of unattended background processes that immediately began to run in the background when initiated by the PHANTOM command. "Conventional" batch jobs were initiated via the JOB command, including the ability to schedule them for a particular time. Networking Primes's main offerings, each covering a specific need, were: PRIMENET RINGNET RJE PRIMENET Prime's PRIMENET software was designed to enable "transparent access to any system in the network without burdening the user with extra commands." With PRIMENET, a user on System A could access files on System B as if they were on System A, or even log into another system using the RLOGIN (Remote Login) command. RINGNET Released similar timing to PRIMENET, it enabled high-speed Local Area Networking. RJE 2780/3790 emulation was included. Primix In 1985, Prime's port of AT&T's UNIX System V, called Primix, became available with Primos Release 19.4.2 that was modified to include Unix functions. It co-existed with PRIMOS, allowing users to switch back and forth. See also List of operating systems Timeline of operating systems References External links Sourcecode Rev 19 Usenet post of Jim Wilcoxson about the Prime 50-series emulator he created, running PRIMOS 19.2 (7 April 2007) Prime Computer FAQ from comp.sys.prime Usenet group Documentation Software Proprietary operating systems Discontinued operating systems Multics-like 1972 software

Operating System (OS)

WebOS webOS, also known as LG webOS and previously known as Open webOS, HP webOS and Palm webOS, is a Linux kernel-based multitasking operating system for smart devices such as smart TVs that has also been used as a mobile operating system. Initially developed by Palm, Inc. (which was acquired by Hewlett-Packard), HP made the platform open source, at which point it became Open webOS. The operating system was later sold to LG Electronics, and was made primarily a smart TV operating system for LG televisions as a successor to LG Netcast. In January 2014, Qualcomm announced that it had acquired technology patents from HP, which included all the webOS and Palm patents; LG licenses them to use in their devices. Various versions of webOS have been featured on several devices since launching in 2009, including Pre, Pixi, and Veer smartphones, TouchPad tablet, LG's smart TVs since 2014, LG's smart refrigerators and smart projectors since 2017. History 2009–2010: Launched by Palm Palm launched webOS, then called Palm webOS, in January 2009 as the successor to Palm OS. The first webOS device was the original Palm Pre, released by Sprint in June 2009. The Palm Pixi followed. Upgraded "Plus" versions of both Pre and Pixi were released on Verizon and AT&T. 2010–2013: Acquired by HP; the launch of Open webOS In April 2010, HP acquired Palm. The acquisition of Palm was initiated while Mark Hurd was CEO, however he resigned shortly after the acquisition was completed. Later, webOS was described by new HP CEO Leo Apotheker as a key asset and motivation for the purchase. The $1.2 billion acquisition finalized in June. HP indicated its intention to develop the webOS platform for use in multiple new products, including smartphones, tablets, and printers. In February 2011, HP announced that it would use webOS as the universal platform for all its devices. However, HP also made the decision that the Palm Pre, Palm Pixi, and the "Plus" revisions would not receive over-the-air updates to webOS 2.0, despite a previous commitment to an upgrade "in coming months." HP announced several webOS devices, including the HP Veer and HP Pre 3 smartphones, running webOS 2.2, and the HP TouchPad, a tablet computer released in July 2011 that runs webOS 3.0. In March 2011, HP announced plans for a version of webOS by the end of 2011 to run within Windows, and to be installed on all HP desktop and notebook computers in 2012. Neither ever materialized, although work had begun on an x86 port around this time involving a team in Fort Collins, Colorado; work was scrapped later in the year. In August 2011, HP announced that it was interested in selling its Personal Systems Group, responsible for all of its consumer PC products, including webOS, and that webOS device development and production lines would be halted. It remained unclear whether HP would consider licensing webOS software to other manufacturers. When HP reduced the price of the Touchpad to $99, the existing inventory quickly sold out. The HP Pre 3 was launched in select areas of Europe, and US-based units were available only through unofficial channels (both AT&T and Verizon canceled their orders just prior to delivery after Apotheker's (HP's CEO at the time) announcement. Notably, these US Pre 3 units, having been released through unofficial channels, lacked both warranties and carried no support obligation from HP; as a result parts are nearly impossible to come by. HP announced that it would continue to issue updates for the HP Veer and HP TouchPad, but these updates have failed to materialize for the former, and the latter saw a final, unofficial release called "webOS CE" that contained only open-sourced components of webOS meant for what remained of the developer community rather than a conventional, user-centric update to the operating system. The last HP webOS version, 3.0.5, was released on January 12, 2012. In December 2011, after abandoning the TouchPad and the proposed sale of the HP Personal Systems Group, HP announced it would release webOS source code in the near future under an open-source license. In August 2012, code specific to the existing devices was released as webOS Community Edition (CE), with support for the existing HP hardware. Open webOS includes open source libraries designed to target a wider range of hardware. HP renamed its webOS unit as "Gram". In February 2012, HP released Isis, a new web browser for Open webOS. Growth and decline of HP App Catalog The HP App Catalog was an app store for apps for the mobile devices running webOS. On June 6, 2009, webOS launched on the Palm Pre with 18 available apps. The number of apps grew to 30 by June 17, 2009, with 1 million cumulative downloads by June 27, 2009; 30 official and 31 unofficial apps by July 13, 2009; 1,000 official apps by January 1, 2010; 4,000 official apps September 29, 2010; and 10,002 official apps on December 9, 2011. Subsequently, the number of available apps decreased because many apps were withdrawn from the App Catalog by their owners. Examples include the apps for The New York Times and Pandora Radio. After a Catalog splash screen on November 11, 2014 announcing its deprecation, the HP App Catalog servers were permanently shut down on March 15, 2015. The number of functional apps remaining at that time is unknown but was probably much lower due to the imminent abandonment of the project. 2013–present: Acquired by LG; open-source edition launched On February 25, 2013, HP announced that it was selling webOS to LG Electronics for use on its web-enabled smart TVs, replacing its previous NetCast platform. Under the agreement LG Electronics owns the documentation, source code, developers and all related websites. However, HP would still hold on to patents from Palm as well as cloud-based services such as the App Catalog. In 2014, HP sold its webOS patents to Qualcomm. As well as its use as an OS for smart TVs, LG has expanded its use to various IoT devices. As a starting point, LG showcased a LG Wearable Platform OS (webOS) smartwatch in early 2015. At CES 2017, LG announced a smart refrigerator with webOS. On March 19, 2018, LG announced an open-source edition of webOS. This edition would allow developers to download the source code for free as well as take advantage of related tools, guides, and forums on its new open source website to become more familiar with webOS and its inherent benefits as a smart device's platform. LG hopes that this will help its goal of advancing its philosophy of open platform, open partnership and open connectivity. Features The webOS mobile platform introduced some innovative features, such as the cards interface, that are still in use by Apple, Microsoft and Google on their mobile operating systems iOS, Windows Phone, and Android, respectively. HP/Palm webOS Multitasking interface Navigation uses multi-touch gestures on the touchscreen. The interface uses "cards" to manage multitasking and represent apps. The user switches between running apps with a flick from left and right on the screen. Apps are closed by flicking a "card" up—and "off"—the screen. The app "cards" can be rearranged for organization. webOS 2.0 introduced 'stacks', where related cards could be "stacked" together. Synergy Palm referred to integration of information from many sources as "Synergy." Users can sign into multiple email accounts from different providers and integrate all of these sources into a single list. Similar capabilities pull together calendars and also instant messages and SMS text messages from multiple sources. Over-the-air updates The OS can be updated without docking to a PC, instead receiving OS updates over the carrier connection. Notifications The notification area is located on the bottom portion of the screen on phones, and on the top status bar area on tablets. On phones, when a notification comes in, it slides in from the bottom of the screen. Due to the resizable nature of the Mojo and Enyo application frameworks, the app usually resizes itself to allow unhindered use while the notification is displayed. After the notification slides away, it usually remains as an icon. The user can then tap on the icons to expand them. Notifications can then be dismissed (sliding off the screen), acted upon (tapping), or left alone. Sync By default, data sync uses a cloud-based approach rather than using a desktop sync client. The first version of webOS shipped with the ability to sync with Apple's iTunes software by masquerading as an Apple device, but this feature was disabled by subsequent iTunes software updates. Third-party applications On HP webOS, officially vetted third-party apps are accessible to be installed on the device from the HP App Catalog. As HP webOS replaced Palm OS, Palm commissioned MotionApps to code and develop an emulator called Classic, to enable backward compatibility to Palm OS apps. This operates with webOS version 1.0. Palm OS emulation was discontinued in WebOS version 2.0. MotionApps disengaged from Classic in 2010, citing HP Palm as "disruptive." Another source of applications is homebrew software. Homebrew apps are not directly supported by HP. Programs used to distribute homebrew webOS apps include webOS Quick Install (Java-based sideloader for desktop computers) and Preware (a homebrew webOS app catalog, which must be sideloaded). If software problems do occur after installing homebrew programs, "webOS Doctor" (provided by HP) can restore a phone back to factory settings and remove changes made by homebrew apps and patches. LG webOS Smart TV features LG has redesigned the UI of webOS, maintaining the card UI as a feature called "Simple switching" between open TV apps. The other two features promoted by the company are a simple connection (using an animated Clippy-like character called Beanbird to aid the user through setup), and simple discovery. Platform Underneath the graphical user interface, webOS has much in common with mainstream Linux distributions. Versions 1.0 to 2.1 use a patched Linux 2.6.24 kernel. The list of open-source components used by the different releases of webOS, as well as the source code of and patches applied to each component, is available at the Palm Open Source webpage. This page also serves as a reference listing of the versions of webOS that have been publicly released. In 2011, Enyo replaced Mojo, released in June 2009, as the software development kit (SDK). Hardware See also List of smart TV platforms and middleware software Enyo Mobile platform Access Linux Platform LuneOS List of WebOS devices References External links webOS Open Source Edition (LG) LG Software Solutions webOS Developer Center LG webOS TV Developer Center webOS Auto Developer Center webOS Internals Wiki 2009 software ARM operating systems LG Electronics Mobile Linux Mobile operating systems Palm, Inc. Smartphones Smart TV Software based on WebKit Tablet operating systems HP software

Operating System (OS)

Universe (Unix) In some versions of the Unix operating system, the term universe was used to denote some variant of the working environment. During the late 1980s, most commercial Unix variants were derived from either System V or BSD. Most versions provided both BSD and System V universes and allowed the user to switch between them. Each universe, typically implemented by separate directory trees or separate filesystems, usually included different versions of commands, libraries, man pages, and header files. While such a facility offered the ability to develop applications portable across both System V and BSD variants, the requirements in disk space and maintenance (separate configuration files, twice the work in patching systems) gave them a problematic reputation. Systems that offered this facility included Harris/Concurrent's CX/UX, Convex's Convex/OS, Apollo's Domain/OS (version 10 only), Pyramid's DC/OSx (dropped in SVR4-based version 2), Concurrent's Masscomp/RTU, MIPS Computer Systems' RISC/os and Siemens' SINIX. Some versions of System V Release 4 retain a system similar to Dual Universe concept, with BSD commands (which behave differently from classic System V commands) in , BSD header files in and library files in . can also be found in NeXTSTEP and OPENSTEP, as well as Solaris. External links Sven Mascheck, DYNIX 3.2.0 and SINIX V5.20 Universes Unix

Operating System (OS)

Windows IoT Windows IoT, formerly Windows Embedded, is a family of operating systems from Microsoft designed for use in embedded systems. Microsoft currently has three different subfamilies of operating systems for embedded devices targeting a wide market, ranging from small-footprint, real-time devices to point of sale (POS) devices like kiosks. Windows Embedded operating systems are available to original equipment manufacturers (OEMs), who make it available to end users preloaded with their hardware, in addition to volume license customers in some cases. In April 2018, Microsoft released Azure Sphere, another operating system designed for IoT applications running on the Linux kernel. The IoT family Microsoft rebranded "Windows Embedded" to "Windows IoT" starting with the release of embedded editions of Windows 10. Enterprise Windows 10 IoT Enterprise branded editions, version 1809 and older, are binary identical to their respective Windows 10 Enterprise editions – Long-Term Servicing Branch (LTSB), Current Branch for Business (CBB), Semi-Annual Channel (SAC), and Long-Term Servicing Channel (LTSC) – but are licensed exclusively for use in embedded devices. This brand replaces the Embedded Industry, Embedded Standard, and "For Embedded Systems" (FES) brands/subfamilies. Plain unlabeled, Retail/Thin Client, Tablet, and Small Tablet SKUs are available, again differing only in licensing. Starting with version 1903, Windows 10 IoT Enterprise has become its own unique edition, and is no longer 100% binary identical to its respective Windows 10 Enterprise edition. It now contains a minor change that allows the use of smaller storage devices, with the possibility of more changes being made in the future. In addition, starting with the LTSC edition of version 21H2, Windows 10 IoT Enterprise LTSC will gain an extra five years of support compared to Windows 10 Enterprise LTSC. Windows 10 IoT Enterprise 2015 (value based pricing): SKU 6EU-00124 - Windows 10 IoT Enterprise 2015 LTSB - High End Edition (Intel Core i7 | Intel XEON | AMD FX) SKU 6EU-00125 - Windows 10 IoT Enterprise 2015 LTSB - Value Edition (Intel Core i3/i5 | AMD R-Series, A10, A8) SKU 6EU-00126 - Windows 10 IoT Enterprise 2015 LTSB- Entry Edition (Intel Atom/Celeron | AMD E1, E2, A4, A6) Windows 10 IoT Enterprise 2016 (value based pricing): SKU 6EU-00034 - Windows 10 IoT Enterprise 2016 LTSB - High End Edition (Intel Core i7 | Intel XEON | AMD FX) SKU 6EU-00035 - Windows 10 IoT Enterprise 2016 LTSB - Value Edition (Intel Core i3/i5 | AMD R-Series, A10, A8) SKU 6EU-00036 - Windows 10 IoT Enterprise 2016 LTSB - Entry Edition (Intel Atom/Celeron | AMD E1, E2, A4, A6) Windows 10 IoT Enterprise 2016 (category based pricing): SKU 6F6-00036 - Windows 10 IoT Enterprise 2016 CBB - High End Edition (Intel Core i7 | Intel XEON | AMD FX) SKU 6F6-00037 - Windows 10 IoT Enterprise 2016 CBB - Value Edition (Intel Core i3/i5 | AMD R-Series, A10, A8) SKU 6F6-00038 - Windows 10 IoT Enterprise 2016 CBB - Entry Edition (Intel Atom/Celeron | AMD E1, E2, A4, A6) SKU 6F6-00036 - Windows 10 IoT Enterprise 2016 SAC - High End Edition (Intel Core i7 | Intel XEON | AMD FX) SKU 6F6-00037 - Windows 10 IoT Enterprise 2016 SAC - Value Edition (Intel Core i3/i5 | AMD R-Series, A10, A8) SKU 6F6-00038 - Windows 10 IoT Enterprise 2016 SAC - Entry Edition (Intel Atom/Celeron | AMD E1, E2, A4, A6) Windows 10 IoT Enterprise 2019 (value based pricing): SKU MUT-00013 - Windows 10 IoT Enterprise 2019 LTSC - High End Edition (Intel Core i7 | Intel XEON | AMD FX) SKU MUU-00005 - Windows 10 IoT Enterprise 2019 LTSC - Value Edition (Intel Core i3/i5 | AMD R-Series, A10, A8) SKU MUV-00005 - Windows 10 IoT Enterprise 2019 LTSC - Entry Edition (Intel Atom/Celeron | AMD E1, E2, A4, A6) Windows 10 IoT Enterprise 2019 (category based pricing): SKU 6F6-00036 - Windows 10 IoT Enterprise 2019 SAC - High End Edition (Intel Core i7 | Intel XEON | AMD FX) SKU 6F6-00037 - Windows 10 IoT Enterprise 2019 SAC - Value Edition (Intel Core i3/i5 | AMD R-Series, A10, A8) SKU 6F6-00038 - Windows 10 IoT Enterprise 2019 SAC - Entry Edition (Intel Atom/Celeron | AMD E1, E2, A4, A6) Mobile Windows 10 IoT Mobile also known as Windows 10 IoT Mobile Enterprise; Unsupported as of January 14, 2020. A binary equivalent of Windows 10 Mobile Enterprise licensed for IoT applications. The successor to Embedded Handheld. Core Windows 10 IoT Core is considered by some to be the successor to Windows Embedded Compact, although it maintains very little compatibility with it. Optimized for smaller and lower-cost industry devices, it is also provided free of charge for use in devices like the Raspberry Pi for hobbyist use. Core Pro Windows 10 IoT Core Pro provides the ability to defer and control updates and is licensed only via distributors; it is otherwise identical to the normal IoT Core edition. Server Windows Server IoT 2019 is a full, binary equivalent version of Windows Server 2019, intended to aggregate data from many 'things'. Like the IoT Enterprise variants, it remains identical in behavior to its regularly licensed counterpart, but differs only in licensing terms. It also is offered in both LTSC and SAC options. Embedded family Embedded Compact Windows Embedded Compact (previously known as Windows Embedded CE or Windows CE) is the variant of Windows Embedded for very small computers and embedded systems, including consumer electronics devices like set-top boxes and video game consoles. Windows Embedded Compact is a modular real-time operating system with a specialized kernel that can run in under 1 MB of memory. It comes with the Platform Builder tool that can be used to add modules to the installation image to create a custom installation, depending on the device used. Windows Embedded Compact is available for ARM, MIPS, SuperH and x86 processor architectures. Microsoft made available a specialized variant of Windows Embedded Compact, known as Windows Mobile, for use in mobile phones. It is a customized image of Windows Embedded Compact along with specialized modules for use in Mobile phones. Windows Mobile was available in four editions: Windows Mobile Classic (for Pocket PC), Windows Mobile Standard (for smartphones) and Windows Mobile Professional (for PDA/Pocket PC Phone Edition) and Windows Mobile for Automotive (for communication/entertainment/information systems used in automobiles). Modified variants of Windows Mobile were used for Portable Media Centers. In 2010, Windows Mobile was replaced by Windows Phone 7, which was also based on Windows Embedded Compact, but was not compatible with any previous products. Windows Embedded Compact 2013 is a real-time operating system which runs on ARM, x86, SH, and derivatives of those architectures. It included .NET Framework, UI framework, and various open source drivers and services as 'modules'. Embedded Standard Windows Embedded Standard is the brand of Windows Embedded operating systems designed to provide enterprises and device manufacturers the freedom to choose which capabilities will be part of their industry devices and intelligent system solutions, intended to build ATMs and devices for the healthcare and manufacturing industries, creating industry-specific devices. This brand consists of Windows NT 4.0 Embedded, Windows XP Embedded, Windows Embedded Standard 2009 (WES09), Windows Embedded 7 Standard (WES7, known as Windows Embedded Standard 2011 prior to release), and Windows Embedded 8 Standard. It provides the full Win32 API. Windows Embedded Standard 2009 includes Silverlight, .NET Framework 3.5, Internet Explorer 7, Windows Media Player 11, RDP 6.1, Network Access Protection, Microsoft Baseline Security Analyzer and support for being managed by Windows Server Update Services and System Center Configuration Manager. Windows Embedded 7 Standard is based on Windows 7 and was previously codenamed Windows Embedded 'Quebec'. Windows Embedded 7 Standard includes Windows Vista and Windows 7 features such as Aero, SuperFetch, ReadyBoost, Windows Firewall, Windows Defender, address space layout randomization, Windows Presentation Foundation, Silverlight 2, Windows Media Center among several other packages. It is available in IA-32 and x64 variants and was released in 2010. It has a larger minimum footprint (~300 MB) compared to 40 MB of XPe and also requires product activation. Windows Embedded 7 Standard was released on April 27, 2010. Windows Embedded 8 Standard was released on March 20, 2013. IE11 for this edition of Windows was released in April 2019, with support for IE10 ending on January 31, 2020. For Embedded Systems (FES) Binary identical variants of the editions as are available in retail, but licensed exclusively for use in embedded devices. They are available for both IA-32 as well as x64 processors. Subfamily is known to include Windows for Workgroups 3.11, Windows 95 to 98, Windows NT Workstation, Windows 2000 Professional, Windows ME, Windows XP Professional, Windows Vista Business and Ultimate, Windows 7 Professional and Ultimate, Windows 8 Pro and Enterprise, and Windows 8.1 Pro and Enterprise. This subfamily originally simply had Embedded tacked onto the end of the SKU name until sometime around the release of Windows XP when the naming scheme changed to FES. Examples of this include Windows NT Workstation Embedded, Windows 2000 Pro Embedded, and Windows ME Embedded. Microsoft changed the moniker for FES products again starting with some Windows 8/8.1 based SKUs, simply labeling them Windows Embedded before the Windows version and edition. Two examples of this are Windows Embedded 8 Pro and Windows Embedded 8.1 Enterprise. Server Windows Embedded Server FES products include Server, Home Server, SQL Server, Storage Server, DPM Server, ISA Server, UAG Server, TMG Server, and Unified Data Storage Server etc. of various years including 2000, 2003, 2003 R2, 2004, 2005, 2006, 2007, 2008, 2008 R2, 2012, and 2012 R2 etc. Embedded Industry Windows Embedded Industry is the brand of Windows Embedded operating systems for industry devices and once only for point of sale systems. This brand was originally limited to the Windows Embedded for Point of Service operating system released in 2006, which is based on Windows XP with SP2. Since, Microsoft has released an updated version of Windows Embedded for Point of service named Windows Embedded POSReady 2009, this time based on Windows XP with SP3. In 2011 Windows Embedded 7 POSReady based on Windows 7 SP1 was released, which succeeded POSReady 2009. Microsoft has since changed the name of this product from "Windows Embedded POSReady" to "Windows Embedded Industry". Microsoft released Windows Embedded 8 Industry in April 2013, followed by 8.1 Industry in October 2013. Embedded NAVReady Windows Embedded NAVReady also called as Navigation Ready which is plug-in component for Windows CE 5.0 and useful for building portable handheld navigation devices. Embedded Automotive Windows Embedded Automotive, formerly Microsoft Auto, Windows CE for Automotive, Windows Automotive, and Windows Mobile for Automotive, is an embedded operating system based on Windows CE for use on computer systems in automobiles. The latest release, Windows Embedded Automotive 7 was announced on October 19, 2010. Embedded Handheld On January 10, 2011, Microsoft announced Windows Embedded Handheld 6.5. The operating system has compatibility with Windows Mobile 6.5 and is presented as an enterprise handheld device, targeting retailers, delivery companies, and other companies that rely on handheld computing. Windows Embedded Handheld retains backward compatibility with legacy Windows Mobile applications. Windows Embedded 8.1 Handheld was released for manufacturing on April 23, 2014. Known simply as Windows Embedded 8 Handheld (WE8H) prior to release, it was designed as the next generation of Windows Embedded Handheld for line-of-business handheld devices and built on Windows Phone 8.1, which it also has compatibility with. Five Windows Embedded 8.1 Handheld devices have been released; Manufactured by Bluebird, Honeywell and Panasonic as listed below. References Further reading External links Embedded Embedded operating systems ARM operating systems

Operating System (OS)

Xenix Xenix is a discontinued version of the Unix operating system for various microcomputer platforms, licensed by Microsoft from AT&T Corporation in the late 1970s. The Santa Cruz Operation (SCO) later acquired exclusive rights to the software, and eventually replaced it with SCO UNIX (now known as SCO OpenServer). In the mid-to-late 1980s, Xenix was the most common Unix variant, measured according to the number of machines on which it was installed. Microsoft chairman Bill Gates said at Unix Expo in 1996 that, for a long time, Microsoft had the highest-volume AT&T Unix license. History Bell Labs, the developer of UNIX, was part of the regulated Bell System and could not sell UNIX directly to most end users (academic and research institutions excepted); it could, however, license it to software vendors who would then resell it to end users (or their own resellers), combined with their own added features. Microsoft, which expected that UNIX would be its operating system of the future when personal computers became powerful enough, 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, the company gave it an original name. Microsoft called XENIX "a universal operating environment". It did not sell XENIX directly to end users, but licensed the software to OEMs such as IBM, Intel, Management Systems Development, Tandy, Altos, SCO, and Siemens (SINIX) which then ported it to their own proprietary computer architectures. In 1981, Microsoft said the first version of XENIX was "very close to the original UNIX version 7 source" on the PDP-11, and later versions were to incorporate its own fixes and improvements. The company stated that it intended to port the operating system to the Zilog Z8000 series, Digital LSI-11, Intel 8086 and 80286, Motorola 68000, and possibly "numerous other processors", and provide Microsoft's "full line of system software products", including BASIC and other languages. The first port was for the Z8001 16-bit processor: the first customer ship was January 1981 for Central Data Corporation of Illinois, followed in March 1981 by Paradyne Corporation's Z8001 product. The first 8086 port was for the Altos Computer Systems' non-PC-compatible 8600-series computers (first customer ship date Q1 1982). Intel sold complete computers with XENIX under their Intel System 86 brand (with specific models such as 86/330 or 86/380X); they also offered the individual boards that made these computers under their iSBC brand. This included processor boards like iSBC 86/12 and also MMU boards such as the iSBC 309. The first Intel XENIX systems shipped in July 1982. Tandy more than doubled the XENIX installed base when it made TRS-XENIX the default operating system for its TRS-80 Model 16 68000-based computer in early 1983, and was the largest UNIX vendor in 1984. Seattle Computer Products also made (PC-incompatible) 8086 computers bundled with XENIX, like their Gazelle II, which used the S-100 bus and was available in late 1983 or early 1984. There was also a port for IBM System 9000. SCO had initially worked on its own PDP-11 port of V7, called Dynix, but then struck an agreement with Microsoft for joint development and technology exchange on XENIX in 1982. Microsoft and SCO then further engaged Human Computing Resources Corporation (HCR) in Canada, and a software products group within Logica plc in the United Kingdom, as part of making further improvements to XENIX and porting XENIX to other platforms. In doing so, Microsoft gave HCR and Logica the rights to do XENIX ports and to license XENIX binary distributions in those territories. In 1984, a port to the 68000-based Apple Lisa 2 was jointly developed by SCO and Microsoft and it was the first shrink-wrapped binary product sold by SCO. The Multiplan spreadsheet was released for it. In its 1983 OEM directory, Microsoft said the difficulty in porting to the various 8086 and Z8000-based machines had been the lack of a standardized memory management unit and protection facilities. Hardware manufacturers compensated by designing their own hardware, but the ensuing complexity made it "extremely difficult if not impossible for the very small manufacturer to develop a computer capable of supporting a system such as XENIX from scratch," and "the XENIX kernel must be custom-tailored to each new hardware environment." A generally available port to the unmapped Intel 8086/8088 architecture was done by The Santa Cruz Operation around 1983. SCO XENIX for the PC XT shipped sometime in 1984 and contained some enhancement from 4.2BSD; it also supported the Micnet local area networking. The later 286 version of XENIX leveraged the integrated MMU present on this chip, by running in 286 protected mode. The 286 XENIX was accompanied by new hardware from XENIX OEMs. For example, the Sperry PC/IT, an IBM PC AT clone, was advertised as capable of supporting eight simultaneous dumb terminal users under this version. While XENIX 2.0 was still based on Version 7 UNIX, version 3.0 was upgraded to a UNIX System III code base, a 1984 Intel manual for XENIX 286 noted that the XENIX kernel had about 10,000 lines at this time. It was followed by a System V R2 codebase in XENIX 5.0 (a.k.a. XENIX System V). "Microsoft hopes that XENIX will become the preferred choice for software production and exchange", the company stated in 1981. Microsoft referred to its own MS-DOS as its "single-user, single-tasking operating system", and advised customers that wanted multiuser or multitasking support to buy XENIX. It planned to over time improve MS-DOS so it would be almost indistinguishable from single-user XENIX, or XEDOS, which would also run on the 68000, Z8000, and LSI-11; they would be upwardly compatible with XENIX, which BYTE in 1983 described as "the multi-user MS-DOS of the future". Microsoft's Chris Larson described MS-DOS 2.0's XENIX compatibility as "the second most important feature". His company advertised DOS and XENIX together, listing the shared features of its "single-user OS" and "the multi-user, multi-tasking, UNIX-derived operating system", and promising easy porting between them. AT&T started selling System V, however, after the breakup of the Bell System. Microsoft, believing that it could not compete with UNIX's developer, decided to abandon XENIX. The decision was not immediately transparent, which led to the term vaporware. It agreed with IBM to develop OS/2, and the XENIX team (together with the best MS-DOS developers) was assigned to that project. In 1987, Microsoft transferred ownership of XENIX to SCO in an agreement that left Microsoft owning slightly less than 20% of SCO (this amount prevented both companies from having to disclose the exact amount in the event of an SCO IPO). And SCO would acquire both of the other companies that had XENIX rights, Logica's software products group in 1986 and HCR in 1990. When Microsoft eventually lost interest in OS/2 as well, the company based its further high-end strategy on Windows NT. In 1987, SCO ported XENIX to the 386 processor, a 32-bit chip, after securing knowledge from Microsoft insiders that Microsoft was no longer developing XENIX. XENIX System V Release 2.3.1 introduced support for i386, SCSI and TCP/IP. SCO's XENIX System V/386 was the first 32-bit operating system available on the market for the x86 CPU architecture. Microsoft continued to use XENIX internally, submitting a patch to support functionality in UNIX to AT&T in 1987, which trickled down to the code base of both XENIX and SCO UNIX. Microsoft is said to have used XENIX on Sun workstations and VAX minicomputers extensively within their company as late as 1988. All internal Microsoft email transport was done on XENIX-based 68000 systems until 1995–1996, when the company moved to its own Exchange Server product. SCO released its SCO UNIX as a higher-end product, based on System V R3 and offering a number of technical advances over XENIX; XENIX remained in the product line. In the meantime, AT&T and Sun Microsystems completed the merge of XENIX, BSD, SunOS and System V R3 into System V R4. The last version of SCO XENIX/386 itself was System V R2.3.4, released in 1991. Features Aside from its AT&T UNIX base, XENIX incorporated elements from BSD, notably the vi text editor and its supporting libraries (termcap and curses). Its kernel featured some original extensions by Microsoft, notably file locking and semaphores, while to the userland Microsoft added a "visual shell" for menu-driven operation instead of the traditional UNIX shell. A limited form of local networking over serial lines (RS-232 ports) was possible through the "micnet" software, which supported file transfer and electronic mail, although UUCP was still used for networking via modems. OEMs often added further modifications to the XENIX system. Trusted XENIX Trusted XENIX was a variant initially developed by IBM, under the name Secure XENIX; later versions, under the Trusted XENIX name, were developed by Trusted Information Systems. It incorporated the Bell-LaPadula model of multilevel security, and had a multilevel secure interface for the STU-III secure communications device (that is, an STU-III connection would be made available only to those applications running at the same privilege level as the key loaded in the STU-III). It was evaluated by formal methods and achieved a B2 security rating under the DoD's Trusted Computer System Evaluation Criteria—the second highest rating ever achieved by an evaluated operating system. Version 2.0 was released in January 1991, version 3.0 in April 1992, and version 4.0 in September 1993. It was still in use as late as 1995. See also AT&T 6300 Plus PC/IX Venix Concurrent DOS Notes References Further reading ; review of the beta SCO XENIX on an XT Covers and compares PC/IX, XENIX and VENIX. External links XENIX timeline XENIX documentation and books for Download XENIX man pages Intel Multibus System 320 for XENIX (or iRMX86) Welcome to comp.unix.xenix.sco (v1.64) https://groups.google.com/d/msg/comp.sys.tandy/UbeLIMssHsE/9isYZrRW-LgJ 1980 software Discontinued Microsoft operating systems Lightweight Unix-like systems Microsoft operating systems UNIX System V Unix variants Discontinued operating systems

Operating System (OS)

Windows 2000 Windows 2000 is a major release of the Windows NT operating system developed by Microsoft and oriented towards businesses. It was the direct successor to Windows NT 4.0, and was released to manufacturing on December 15, 1999, and was officially released to retail on February 17, 2000. It was Microsoft's business operating system until the introduction of Windows XP in 2001. Windows 2000 introduced NTFS 3.0, Encrypting File System, as well as basic and dynamic disk storage. Support for people with disabilities was improved over Windows NT 4.0 with a number of new assistive technologies, and Microsoft increased support for different languages and locale information. The Windows 2000 Server family has additional features, most notably the introduction of Active Directory, which in the years following became a widely used directory service in business environments. Four editions of Windows 2000 were released: Professional, Server, Advanced Server, and Datacenter Server; the latter was both released to manufacturing and launched months after the other editions. While each edition of Windows 2000 was targeted at a different market, they shared a core set of features, including many system utilities such as the Microsoft Management Console and standard system administration applications. Microsoft marketed Windows 2000 as the most secure Windows version ever at the time; however, it became the target of a number of high-profile virus attacks such as Code Red and Nimda. For ten years after its release, it continued to receive patches for security vulnerabilities nearly every month until reaching the end of its lifecycle on July 13, 2010. Windows 2000 and Windows 2000 Server were succeeded by Windows XP and Windows Server 2003, released in 2001 and 2003, respectively. Windows 2000's successor, Windows XP, became the minimum supported OS for most Windows programs up until Windows 7 replaced it, and unofficial methods were made to run these programs on Windows 2000. Windows 2000 is the final version of Windows which supports PC-98, I486 and SGI Visual Workstation 320 and 540, as well as Alpha, MIPS and PowerPC in alpha, beta, and release candidate versions. Its successor, Windows XP, requires a processor in any supported architecture (IA-32 for 32-bit CPUs and x86-64 and Itanium for 64-bit CPUs). History Windows 2000 is a continuation of the Microsoft Windows NT family of operating systems, replacing Windows NT 4.0. The original name for the operating system was Windows NT 5.0 and the prep beta builds were compiled between March to August 1997, these builds were identical to Windows NT 4.0. The first official beta was released in September 1997, followed by Beta 2 in August 1998. On October 27, 1998, Microsoft announced that the name of the final version of the operating system would be Windows 2000, a name which referred to its projected release date. Windows 2000 Beta 3 was released in May 1999. NT 5.0 Beta 1 was similar to NT 4.0, including a very similarly themed logo. NT 5.0 Beta 2 introduced a new 'mini' boot screen, and removed the 'dark space' theme in the logo. The NT 5.0 betas had very long startup and shutdown sounds, though these were changed in the early Windows 2000 beta, but during Beta 3, a new piano-made startup and shutdown sounds were made, featured in the final version as well as in Windows Me. The new login prompt from the final version made its first appearance in Beta 3 build 1946 (the first build of Beta 3). The new, updated icons (for My Computer, Recycle Bin etc.) first appeared in Beta 3 build 1964. The Windows 2000 boot screen in the final version first appeared in Beta 3 build 1983. Windows 2000 did not have an actual codename because, according to Dave Thompson of Windows NT team, "Jim Allchin didn't like codenames". Windows 2000 Service Pack 1 was codenamed "Asteroid" and Windows 2000 64-bit was codenamed "Janus." During development, there was a build for the Alpha which was abandoned in the final stages of development (between RC1 and RC2) after Compaq announced they had dropped support for Windows NT on Alpha. From here, Microsoft issued three release candidates between July and November 1999, and finally released the operating system to partners on December 12, 1999, followed by manufacturing three days later on December 15. The public could buy the full version of Windows 2000 on February 17, 2000. Three days before this event, which Microsoft advertised as "a standard in reliability," a leaked memo from Microsoft reported on by Mary Jo Foley revealed that Windows 2000 had "over 63,000 potential known defects." After Foley's article was published, she claimed that Microsoft blacklisted her for a considerable time. However, Abraham Silberschatz et al. claim in their computer science textbook that "Windows 2000 was the most reliable, stable operating system Microsoft had ever shipped to that point. Much of this reliability came from maturity in the source code, extensive stress testing of the system, and automatic detection of many serious errors in drivers." InformationWeek summarized the release "our tests show the successor to NT 4.0 is everything we hoped it would be. Of course, it isn't perfect either." Wired News later described the results of the February launch as "lackluster." Novell criticized Microsoft's Active Directory, the new directory service architecture, as less scalable or reliable than its own Novell Directory Services (NDS) alternative. Windows 2000 was initially planned to replace both Windows 98 and Windows NT 4.0. However, this changed later, as an updated version of Windows 98 called Windows 98 SE was released in 1999. On or shortly before February 12, 2004, "portions of the Microsoft Windows 2000 and Windows NT 4.0 source code were illegally made available on the Internet." The source of the leak was later traced to Mainsoft, a Windows Interface Source Environment partner. Microsoft issued the following statement: "Microsoft source code is both copyrighted and protected as a trade secret. As such, it is illegal to post it, make it available to others, download it or use it." Despite the warnings, the archive containing the leaked code spread widely on the file-sharing networks. On February 16, 2004, an exploit "allegedly discovered by an individual studying the leaked source code" for certain versions of Microsoft Internet Explorer was reported. On April 15, 2015, GitHub took down a repository containing a copy of the Windows NT 4.0 source code that originated from the leak. Microsoft planned to release a 64-bit version of Windows 2000, which would run on 64-bit Intel Itanium microprocessors, in 2000. However, the first officially released 64-bit version of Windows was Windows XP 64-Bit Edition, released alongside the 32-bit editions of Windows XP on October 25, 2001, followed by the server versions Windows Datacenter Server Limited Edition and later Windows Advanced Server Limited Edition, which were based on the pre-release Windows Server 2003 (then known as Windows .NET Server) codebase. These editions were released in 2002, were shortly available through the OEM channel and then were superseded by the final versions of Server 2003. New and updated features Windows 2000 introduced many of the new features of Windows 98 and 98 SE into the NT line, such as the Windows Desktop Update, Internet Explorer 5 (Internet Explorer 6, which followed in 2001, is also available for Windows 2000), Outlook Express, NetMeeting, FAT32 support, Windows Driver Model, Internet Connection Sharing, Windows Media Player, WebDAV support etc. Certain new features are common across all editions of Windows 2000, among them NTFS 3.0, the Microsoft Management Console (MMC), UDF support, the Encrypting File System (EFS), Logical Disk Manager, Image Color Management 2.0, support for PostScript 3-based printers, OpenType (.OTF) and Type 1 PostScript (.PFB) font support (including a new font—Palatino Linotype—to showcase some OpenType features), the Data protection API (DPAPI), an LDAP/Active Directory-enabled Address Book, usability enhancements and multi-language and locale support. Windows 2000 also introduced USB device class drivers for USB printers, Mass storage class devices, and improved FireWire SBP-2 support for printers and scanners, along with a Safe removal applet for storage devices. Windows 2000 SP4 has added the native USB 2.0 support. Windows 2000 is also the first Windows version to support hibernation at the operating system level (OS-controlled ACPI S4 sleep state) unlike Windows 98 which required special drivers from the hardware manufacturer or driver developer. A new capability designed to protect critical system files called Windows File Protection was introduced. This protects critical Windows system files by preventing programs other than Microsoft's operating system update mechanisms such as the Package Installer, Windows Installer and other update components from modifying them. The System File Checker utility provides users the ability to perform a manual scan of the integrity of all protected system files, and optionally repair them, either by restoring from a cache stored in a separate "DLLCACHE" directory, or from the original install media. Microsoft recognized that a serious error (a Blue Screen of Death or stop error) could cause problems for servers that needed to be constantly running and so provided a system setting that would allow the server to automatically reboot when a stop error occurred. Also included is an option to dump any of the first 64 KB of memory to disk (the smallest amount of memory that is useful for debugging purposes, also known as a minidump), a dump of only the kernel's memory, or a dump of the entire contents of memory to disk, as well as write that this event happened to the Windows 2000 event log. In order to improve performance on servers running Windows 2000, Microsoft gave administrators the choice of optimizing the operating system's memory and processor usage patterns for background services or for applications. Windows 2000 also introduced core system administration and management features as the Windows Installer, Windows Management Instrumentation and Event Tracing for Windows (ETW) into the operating system. Plug and Play and hardware support improvements The most notable improvement from Windows NT 4.0 is the addition of Plug and Play with full ACPI and Windows Driver Model support. Similar to Windows 9x, Windows 2000 supports automatic recognition of installed hardware, hardware resource allocation, loading of appropriate drivers, PnP APIs and device notification events. The addition of the kernel PnP Manager along with the Power Manager are two significant subsystems added in Windows 2000. Windows 2000 introduced version 3 print drivers (user mode printer drivers) based on Unidrv, which made it easier for printer manufacturers to write device drivers for printers. Generic support for 5-button mice is also included as standard and installing IntelliPoint allows reassigning the programmable buttons. Windows 98 lacked generic support. Driver Verifier was introduced to stress test and catch device driver bugs. Shell Windows 2000 introduces layered windows that allow for transparency, translucency and various transition effects like shadows, gradient fills and alpha-blended GUI elements to top-level windows. Menus support a new Fade transition effect. The Start menu in Windows 2000 introduces personalized menus, expandable special folders and the ability to launch multiple programs without closing the menu by holding down the SHIFT key. A Re-sort button forces the entire Start Menu to be sorted by name. The Taskbar introduces support for balloon notifications which can also be used by application developers. Windows 2000 Explorer introduces customizable Windows Explorer toolbars, auto-complete in Windows Explorer address bar and Run box, advanced file type association features, displaying comments in shortcuts as tooltips, extensible columns in Details view (IColumnProvider interface), icon overlays, integrated search pane in Windows Explorer, sort by name function for menus, and Places bar in common dialogs for Open and Save. Windows Explorer has been enhanced in several ways in Windows 2000. It is the first Windows NT release to include Active Desktop, first introduced as a part of Internet Explorer 4.0 (specifically Windows Desktop Update), and only pre-installed in Windows 98 by that time. It allowed users to customize the way folders look and behave by using HTML templates, having the file extension HTT. This feature was abused by computer viruses that employed malicious scripts, Java applets, or ActiveX controls in folder template files as their infection vector. Two such viruses are VBS/Roor-C and VBS.Redlof.a. The "Web-style" folders view, with the left Explorer pane displaying details for the object currently selected, is turned on by default in Windows 2000. For certain file types, such as pictures and media files, the preview is also displayed in the left pane. Until the dedicated interactive preview pane appeared in Windows Vista, Windows 2000 had been the only Windows release to feature an interactive media player as the previewer for sound and video files, enabled by default. However, such a previewer can be enabled in previous versions of Windows with the Windows Desktop Update installed through the use of folder customization templates. The default file tooltip displays file title, author, subject and comments; this metadata may be read from a special NTFS stream, if the file is on an NTFS volume, or from an OLE structured storage stream, if the file is a structured storage document. All Microsoft Office documents since Office 4.0 make use of structured storage, so their metadata is displayable in the Windows 2000 Explorer default tooltip. File shortcuts can also store comments which are displayed as a tooltip when the mouse hovers over the shortcut. The shell introduces extensibility support through metadata handlers, icon overlay handlers and column handlers in Explorer Details view. The right pane of Windows 2000 Explorer, which usually just lists files and folders, can also be customized. For example, the contents of the system folders aren't displayed by default, instead showing in the right pane a warning to the user that modifying the contents of the system folders could harm their computer. It's possible to define additional Explorer panes by using DIV elements in folder template files. This degree of customizability is new to Windows 2000; neither Windows 98 nor the Desktop Update could provide it. The new DHTML-based search pane is integrated into Windows 2000 Explorer, unlike the separate search dialog found in all previous Explorer versions. The Indexing Service has also been integrated into the operating system and the search pane built into Explorer allows searching files indexed by its database. NTFS 3.0 Microsoft released the version 3.0 of NTFS (sometimes incorrectly called "NTFS 5" in relation to the kernel version number) as part of Windows 2000; this introduced disk quotas (provided by QuotaAdvisor), file-system-level encryption, sparse files and reparse points. Sparse files allow for the efficient storage of data sets that are very large yet contain many areas that only have zeros. Reparse points allow the object manager to reset a file namespace lookup and let file system drivers implement changed functionality in a transparent manner. Reparse points are used to implement volume mount points, junctions, Hierarchical Storage Management, Native Structured Storage and Single Instance Storage. Volume mount points and directory junctions allow for a file to be transparently referred from one file or directory location to another. Windows 2000 also introduces a Distributed Link Tracking service to ensure file shortcuts remain working even if the target is moved or renamed. The target object's unique identifier is stored in the shortcut file on NTFS 3.0 and Windows can use the Distributed Link Tracking service for tracking the targets of shortcuts, so that the shortcut file may be silently updated if the target moves, even to another hard drive. Encrypting File System The Encrypting File System (EFS) introduced strong file system-level encryption to Windows. It allows any folder or drive on an NTFS volume to be encrypted transparently by the user. EFS works together with the EFS service, Microsoft's CryptoAPI and the EFS File System Runtime Library (FSRTL). To date, its encryption has not been compromised. EFS works by encrypting a file with a bulk symmetric key (also known as the File Encryption Key, or FEK), which is used because it takes less time to encrypt and decrypt large amounts of data than if an asymmetric key cipher were used. The symmetric key used to encrypt the file is then encrypted with a public key associated with the user who encrypted the file, and this encrypted data is stored in the header of the encrypted file. To decrypt the file, the file system uses the private key of the user to decrypt the symmetric key stored in the file header. It then uses the symmetric key to decrypt the file. Because this is done at the file system level, it is transparent to the user. For a user losing access to their key, support for recovery agents that can decrypt files is built into EFS. A Recovery Agent is a user who is authorized by a public key recovery certificate to decrypt files belonging to other users using a special private key. By default, local administrators are recovery agents however they can be customized using Group Policy. Basic and dynamic disk storage Windows 2000 introduced the Logical Disk Manager and the diskpart command line tool for dynamic storage. All versions of Windows 2000 support three types of dynamic disk volumes (along with basic disks): simple volumes, spanned volumes and striped volumes: Simple volume, a volume with disk space from one disk. Spanned volumes, where up to 32 disks show up as one, increasing it in size but not enhancing performance. When one disk fails, the array is destroyed. Some data may be recoverable. This corresponds to JBOD and not to RAID-1. Striped volumes, also known as RAID-0, store all their data across several disks in stripes. This allows better performance because disk reads and writes are balanced across multiple disks. Like spanned volumes, when one disk in the array fails, the entire array is destroyed (some data may be recoverable). In addition to these disk volumes, Windows 2000 Server, Windows 2000 Advanced Server, and Windows 2000 Datacenter Server support mirrored volumes and striped volumes with parity: Mirrored volumes, also known as RAID-1, store identical copies of their data on 2 or more identical disks (mirrored). This allows for fault tolerance; in the event one disk fails, the other disk(s) can keep the server operational until the server can be shut down for replacement of the failed disk. Striped volumes with parity, also known as RAID-5, functions similar to striped volumes/RAID-0, except "parity data" is written out across each of the disks in addition to the data. This allows the data to be "rebuilt" in the event a disk in the array needs replacement. Accessibility With Windows 2000, Microsoft introduced the Windows 9x accessibility features for people with visual and auditory impairments and other disabilities into the NT-line of operating systems. These included: StickyKeys: makes modifier keys (ALT, CTRL and SHIFT) become "sticky": a user can press the modifier key, and then release it before pressing the combination key. (Activated by pressing Shift five times quickly.) FilterKeys: a group of keyboard-related features for people with typing issues, including: Slow Keys: Ignore any keystroke not held down for a certain period. Bounce Keys: Ignore repeated keystrokes pressed in quick succession. Repeat Keys: lets users slow down the rate at which keys are repeated via the keyboard's key-repeat feature. Toggle Keys: when turned on, Windows will play a sound when the CAPS LOCK, NUM LOCK or SCROLL LOCK key is pressed. SoundSentry: designed to help users with auditory impairments, Windows 2000 shows a visual effect when a sound is played through the sound system. MouseKeys: lets users move the cursor around the screen via the numeric keypad. SerialKeys: lets Windows 2000 support speech augmentation devices. High contrast theme: to assist users with visual impairments. Microsoft Magnifier: a screen magnifier that enlarges a part of the screen the cursor is over. Additionally, Windows 2000 introduced the following new accessibility features: On-screen keyboard: displays a virtual keyboard on the screen and allows users to press its keys using a mouse or a joystick. Microsoft Narrator: introduced in Windows 2000, this is a screen reader that utilizes the Speech API 4, which would later be updated to Speech API 5 in Windows XP Utility Manager: an application designed to start, stop, and manage when accessibility features start. This was eventually replaced by the Ease of Access Center in Windows Vista. Accessibility Wizard: a control panel applet that helps users set up their computer for people with disabilities. Languages and locales Windows 2000 introduced the Multilingual User Interface (MUI). Besides English, Windows 2000 incorporates support for Arabic, Armenian, Baltic, Central European, Cyrillic, Georgian, Greek, Hebrew, Indic, Japanese, Korean, Simplified Chinese, Thai, Traditional Chinese, Turkic, Vietnamese and Western European languages. It also has support for many different locales. Games Windows 2000 included version 7.0 of the DirectX API, commonly used by game developers on Windows 98. The last version of DirectX that was released for Windows 2000 was DirectX 9.0c (Shader Model 3.0), which shipped with Windows XP Service Pack 2. Microsoft published quarterly updates to DirectX 9.0c through the February 2010 release after which support was dropped in the June 2010 SDK. These updates contain bug fixes to the core runtime and some additional libraries such as D3DX, XAudio 2, XInput and Managed DirectX components. The majority of games written for versions of DirectX 9.0c (up to the February 2010 release) can therefore run on Windows 2000. Windows 2000 included the same games as Windows NT 4.0 did: FreeCell, Minesweeper, Pinball, and Solitaire. System utilities Windows 2000 introduced the Microsoft Management Console (MMC), which is used to create, save, and open administrative tools. Each of these is called a console, and most allow an administrator to administer other Windows 2000 computers from one centralised computer. Each console can contain one or many specific administrative tools, called snap-ins. These can be either standalone (with one function), or an extension (adding functions to an existing snap-in). In order to provide the ability to control what snap-ins can be seen in a console, the MMC allows consoles to be created in author mode or user mode. Author mode allows snap-ins to be added, new windows to be created, all portions of the console tree to be displayed and consoles to be saved. User mode allows consoles to be distributed with restrictions applied. User mode consoles can grant full access to the user for any change, or they can grant limited access, preventing users from adding snapins to the console though they can view multiple windows in a console. Alternatively users can be granted limited access, preventing them from adding to the console and stopping them from viewing multiple windows in a single console. The main tools that come with Windows 2000 can be found in the Computer Management console (in Administrative Tools in the Control Panel). This contains the Event Viewer—a means of seeing events and the Windows equivalent of a log file, a system information utility, a backup utility, Task Scheduler and management consoles to view open shared folders and shared folder sessions, configure and manage COM+ applications, configure Group Policy, manage all the local users and user groups, and a device manager. It contains Disk Management and Removable Storage snap-ins, a disk defragmenter as well as a performance diagnostic console, which displays graphs of system performance and configures data logs and alerts. It also contains a service configuration console, which allows users to view all installed services and to stop and start them, as well as configure what those services should do when the computer starts. CHKDSK has significant performance improvements. Windows 2000 comes with two utilities to edit the Windows registry, REGEDIT.EXE and REGEDT32.EXE. REGEDIT has been directly ported from Windows 98, and therefore does not support editing registry permissions. REGEDT32 has the older multiple document interface (MDI) and can edit registry permissions in the same manner that Windows NT's REGEDT32 program could. REGEDIT has a left-side tree view of the Windows registry, lists all loaded hives and represents the three components of a value (its name, type, and data) as separate columns of a table. REGEDT32 has a left-side tree view, but each hive has its own window, so the tree displays only keys and it represents values as a list of strings. REGEDIT supports right-clicking of entries in a tree view to adjust properties and other settings. REGEDT32 requires all actions to be performed from the top menu bar. Windows XP is the first system to integrate these two programs into a single utility, adopting the REGEDIT behavior with the additional NT features. The System File Checker (SFC) also comes with Windows 2000. It is a command line utility that scans system files and verifies whether they were signed by Microsoft and works in conjunction with the Windows File Protection mechanism. It can also repopulate and repair all the files in the Dllcache folder. Recovery Console The Recovery Console is run from outside the installed copy of Windows to perform maintenance tasks that can neither be run from within it nor feasibly be run from another computer or copy of Windows 2000. It is usually used to recover the system from problems that cause booting to fail, which would render other tools useless, like Safe Mode or Last Known Good Configuration, or chkdsk. It includes commands like fixmbr, which are not present in MS-DOS. It has a simple command-line interface, used to check and repair the hard drive(s), repair boot information (including NTLDR), replace corrupted system files with fresh copies from the CD, or enable/disable services and drivers for the next boot. The console can be accessed in either of the two ways: Booting from the Windows 2000 CD, and choosing to start the Recovery Console from the CD itself instead of continuing with setup. The Recovery Console is accessible as long as the installation CD is available. Preinstalling the Recovery Console on the hard disk as a startup option in Boot.ini, via WinNT32.exe, with the /cmdcons switch. In this case, it can only be started as long as NTLDR can boot from the system partition. Windows Scripting Host 2.0 Windows 2000 introduced Windows Script Host 2.0 which included an expanded object model and support for logon and logoff scripts. Networking Starting with Windows 2000, the Server Message Block (SMB) protocol directly interfaces with TCP/IP. In Windows NT 4.0, SMB requires the NetBIOS over TCP/IP (NBT) protocol to work on a TCP/IP network. Windows 2000 introduces a client-side DNS caching service. When the Windows DNS resolver receives a query response, the DNS resource record is added to a cache. When it queries the same resource record name again and it is found in the cache, then the resolver does not query the DNS server. This speeds up DNS query time and reduces network traffic. Server family features The Windows 2000 Server family consists of Windows 2000 Server, Windows 2000 Advanced Server, Windows 2000 Small Business Server, and Windows 2000 Datacenter Server. All editions of Windows 2000 Server have the following services and features built in: Routing and Remote Access Service (RRAS) support, facilitating dial-up and VPN connections using IPsec, L2TP or L2TP/IPsec, support for RADIUS authentication in Internet Authentication Service, network connection sharing, Network Address Translation, unicast and multicast routing schemes. Remote access security features: Remote Access Policies for setup, verify Caller ID (IP address for VPNs), callback and Remote access account lockout Autodial by location feature using the Remote Access Auto Connection Manager service Extensible Authentication Protocol support in IAS (EAP-MD5 and EAP-TLS) later upgraded to PEAPv0/EAP-MSCHAPv2 and PEAP-EAP-TLS in Windows 2000 SP4 DNS server, including support for Dynamic DNS. Active Directory relies heavily on DNS. IPsec support and TCP/IP filtering Smart card support Microsoft Connection Manager Administration Kit (CMAK) and Connection Point Services Support for distributed file systems (DFS) Hierarchical Storage Management support including remote storage, a service that runs with NTFS and automatically transfers files that are not used for some time to less expensive storage media Fault tolerant volumes, namely Mirrored and RAID-5 Group Policy (part of Active Directory) IntelliMirror, a collection of technologies for fine-grained management of Windows 2000 Professional clients that duplicates users' data, applications, files, and settings in a centralized location on the network. IntelliMirror employs technologies such as Group Policy, Windows Installer, Roaming profiles, Folder Redirection, Offline Files (also known as Client Side Caching or CSC), File Replication Service (FRS), Remote Installation Services (RIS) to address desktop management scenarios such as user data management, user settings management, software installation and maintenance. COM+, Microsoft Transaction Server and Distributed Transaction Coordinator MSMQ 2.0 TAPI 3.0 Integrated Windows Authentication (including Kerberos, Secure channel and SPNEGO (Negotiate) SSP packages for Security Support Provider Interface (SSPI)). MS-CHAP v2 protocol Public Key Infrastructure (PKI) and Enterprise Certificate Authority support Terminal Services and support for the Remote Desktop Protocol (RDP) Internet Information Services (IIS) 5.0 and Windows Media Services 4.1 Network quality of service features A new Windows Time service which is an implementation of Simple Network Time Protocol (SNTP) as detailed in IETF . The Windows Time service synchronizes the date and time of computers in a domain running on Windows 2000 Server or later. Windows 2000 Professional includes an SNTP client. The Server editions include more features and components, including the Microsoft Distributed File System (DFS), Active Directory support and fault-tolerant storage. Distributed File System The Distributed File System (DFS) allows shares in multiple different locations to be logically grouped under one folder, or DFS root. When users try to access a network share off the DFS root, the user is really looking at a DFS link and the DFS server transparently redirects them to the correct file server and share. A DFS root can only exist on a Windows 2000 version that is part of the server family, and only one DFS root can exist on that server. There can be two ways of implementing a DFS namespace on Windows 2000: either through a standalone DFS root or a domain-based DFS root. Standalone DFS allows for only DFS roots on the local computer, and thus does not use Active Directory. Domain-based DFS roots exist within Active Directory and can have their information distributed to other domain controllers within the domain – this provides fault tolerance to DFS. DFS roots that exist on a domain must be hosted on a domain controller or on a domain member server. The file and root information is replicated via the Microsoft File Replication Service (FRS). Active Directory A new way of organizing Windows network domains, or groups of resources, called Active Directory, is introduced with Windows 2000 to replace Windows NT's earlier domain model. Active Directory's hierarchical nature allowed administrators a built-in way to manage user and computer policies and user accounts, and to automatically deploy programs and updates with a greater degree of scalability and centralization than provided in previous Windows versions. User information stored in Active Directory also provided a convenient phone book-like function to end users. Active Directory domains can vary from small installations with a few hundred objects, to large installations with millions. Active Directory can organise and link groups of domains into a contiguous domain name space to form trees. Groups of trees outside of the same namespace can be linked together to form forests. Active Directory services could always be installed on a Windows 2000 Server Standard, Advanced, or Datacenter computer, and cannot be installed on a Windows 2000 Professional computer. However, Windows 2000 Professional is the first client operating system able to exploit Active Directory's new features. As part of an organization's migration, Windows NT clients continued to function until all clients were upgraded to Windows 2000 Professional, at which point the Active Directory domain could be switched to native mode and maximum functionality achieved. Active Directory requires a DNS server that supports SRV resource records, or that an organization's existing DNS infrastructure be upgraded to support this. There should be one or more domain controllers to hold the Active Directory database and provide Active Directory directory services. Volume fault tolerance Along with support for simple, spanned and striped volumes, the Windows 2000 Server family also supports fault-tolerant volume types. The types supported are mirrored volumes and RAID-5 volumes: Mirrored volumes: the volume contains several disks, and when data is written to one it is also written to the other disks. This means that if one disk fails, the data can be totally recovered from the other disk. Mirrored volumes are also known as RAID-1. RAID-5 volumes: a RAID-5 volume consists of multiple disks, and it uses block-level striping with parity data distributed across all member disks. Should a disk fail in the array, the parity blocks from the surviving disks are combined mathematically with the data blocks from the surviving disks to reconstruct the data on the failed drive "on-the-fly." Deployment Windows 2000 can be deployed to a site via various methods. It can be installed onto servers via traditional media (such as CD) or via distribution folders that reside on a shared folder. Installations can be attended or unattended. During a manual installation, the administrator must specify configuration options. Unattended installations are scripted via an answer file, or a predefined script in the form of an INI file that has all the options filled in. An answer file can be created manually or using the graphical Setup manager. The Winnt.exe or Winnt32.exe program then uses that answer file to automate the installation. Unattended installations can be performed via a bootable CD, using Microsoft Systems Management Server (SMS), via the System Preparation Tool (Sysprep), via the Winnt32.exe program using the /syspart switch or via Remote Installation Services (RIS). The ability to slipstream a service pack into the original operating system setup files is also introduced in Windows 2000. The Sysprep method is started on a standardized reference computer – though the hardware need not be similar – and it copies the required installation files from the reference computer to the target computers. The hard drive does not need to be in the target computer and may be swapped out to it at any time, with the hardware configured later. The Winnt.exe program must also be passed a /unattend switch that points to a valid answer file and a /s file that points to one or more valid installation sources. Sysprep allows the duplication of a disk image on an existing Windows 2000 Server installation to multiple servers. This means that all applications and system configuration settings will be copied across to the new installations, and thus, the reference and target computers must have the same HALs, ACPI support, and mass storage devices – though Windows 2000 automatically detects "plug and play" devices. The primary reason for using Sysprep is to quickly deploy Windows 2000 to a site that has multiple computers with standard hardware. (If a system had different HALs, mass storage devices or ACPI support, then multiple images would need to be maintained.) Systems Management Server can be used to upgrade multiple computers to Windows 2000. These must be running Windows NT 3.51, Windows NT 4.0, Windows 98 or Windows 95 OSR2.x along with the SMS client agent that can receive software installation operations. Using SMS allows installations over a wide area and provides centralised control over upgrades to systems. Remote Installation Services (RIS) are a means to automatically install Windows 2000 Professional (and not Windows 2000 Server) to a local computer over a network from a central server. Images do not have to support specific hardware configurations and the security settings can be configured after the computer reboots as the service generates a new unique security ID (SID) for the machine. This is required so that local accounts are given the right identifier and do not clash with other Windows 2000 Professional computers on a network. RIS requires that client computers are able to boot over the network via either a network interface card that has a Pre-Boot Execution Environment (PXE) boot ROM installed or that the client computer has a network card installed that is supported by the remote boot disk generator. The remote computer must also meet the Net PC specification. The server that RIS runs on must be Windows 2000 Server and it must be able to access a network DNS Service, a DHCP service and the Active Directory services. Editions Microsoft released various editions of Windows 2000 for different markets and business needs: Professional, Server, Advanced Server and Datacenter Server. Each was packaged separately. Windows 2000 Professional was designed as the desktop operating system for businesses and power users. It is the client version of Windows 2000. It offers greater security and stability than many of the previous Windows desktop operating systems. It supports up to two processors, and can address up to 4GB of RAM. The system requirements are a Pentium processor (or equivalent) of 133MHz or greater, at least 32MB of RAM, 650MB of hard drive space, and a CD-ROM drive (recommended: Pentium II, 128MB of RAM, 2GB of hard drive space, and CD-ROM drive). However, despite the official minimum processor requirements, it is still possible to install Windows 2000 on 4th-generation x86 CPUs such as the 80486. Windows 2000 Server shares the same user interface with Windows 2000 Professional, but contains additional components for the computer to perform server roles and run infrastructure and application software. A significant new component introduced in the server versions is Active Directory, which is an enterprise-wide directory service based on LDAP (Lightweight Directory Access Protocol). Additionally, Microsoft integrated Kerberos network authentication, replacing the often-criticised NTLM (NT LAN Manager) authentication system used in previous versions. This also provided a purely transitive-trust relationship between Windows 2000 Server domains in a forest (a collection of one or more Windows 2000 domains that share a common schema, configuration, and global catalog, being linked with two-way transitive trusts). Furthermore, Windows 2000 introduced a Domain Name Server which allows dynamic registration of IP addresses. Windows 2000 Server supports up to 4 processors and 4GB of RAM, with a minimum requirement of 128MB of RAM and 1GB hard disk space, however requirements may be higher depending on installed components. Windows 2000 Advanced Server is a variant of Windows 2000 Server operating system designed for medium-to-large businesses. It offers the ability to create clusters of servers, support for up to 8 CPUs, a main memory amount of up to 8GB on Physical Address Extension (PAE) systems and the ability to do 8-way SMP. It supports TCP/IP load balancing and builds on Microsoft Cluster Server (MSCS) in Windows NT Enterprise Server 4.0, adding enhanced functionality for two-node clusters. System requirements are similar to those of Windows 2000 Server, however they may need to be higher to scale to larger infrastructure. Windows 2000 Datacenter Server is a variant of Windows 2000 Server designed for large businesses that move large quantities of confidential or sensitive data frequently via a central server. Like Advanced Server, it supports clustering, failover and load balancing. Its minimum system requirements are normal, but it was designed to be capable of handing advanced, fault-tolerant and scalable hardware—for instance computers with up to 32 CPUs and 32GBs RAM, with rigorous system testing and qualification, hardware partitioning, coordinated maintenance and change control. System requirements are similar to those of Windows 2000 Server Advanced, however they may need to be higher to scale to larger infrastructure. Windows 2000 Datacenter Server was released to manufacturing on August 11, 2000 and launched on September 26, 2000. This edition was based on Windows 2000 with Service Pack 1 and was not available at retail. Service packs Windows 2000 has received four full service packs and one rollup update package following SP4, which is the last service pack. Microsoft phased out all development of its Java Virtual Machine (JVM) from Windows 2000 in SP3. Internet Explorer 5.01 has also been upgraded to the corresponding service pack level. Service Pack 4 with Update Rollup was released on September 13, 2005, nearly four years following the release of Windows XP and sixteen months prior to the release of Windows Vista. Microsoft had originally intended to release a fifth service pack for Windows 2000, but Microsoft cancelled this project early in its development, and instead released Update Rollup 1 for SP4, a collection of all the security-related hotfixes and some other significant issues. The Update Rollup does not include all non-security related hotfixes and is not subjected to the same extensive regression testing as a full service pack. Microsoft states that this update will meet customers' needs better than a whole new service pack, and will still help Windows 2000 customers secure their PCs, reduce support costs, and support existing computer hardware. Upgradeability Several Windows 2000 components are upgradable to latest versions, which include new versions introduced in later versions of Windows, and other major Microsoft applications are available. These latest versions for Windows 2000 include: ActiveSync 4.5 DirectX 9.0c (5 February 2010 Redistributable) Internet Explorer 6 SP1 and Outlook Express 6 SP1 Microsoft Agent 2.0 Microsoft Data Access Components 2.81 Microsoft NetMeeting 3.01 and Microsoft Office 2003 on Windows 2000 SP3 and SP4 (and Microsoft Office XP on Windows 2000 versions below SP3.) MSN Messenger 7.0 (Windows Messenger) MSXML 6.0 SP2 .NET Framework 2.0 SP2 Tweak UI 1.33 Visual C++ 2008 Visual Studio 2005 Windows Desktop Search 2.66 Windows Script Host 5.7 Windows Installer 3.1 Windows Media Format Runtime and Windows Media Player 9 Series (including Windows Media Encoder 7.1 and the Windows Media 8 Encoding Utility) Security During the Windows 2000 period, the nature of attacks on Windows servers changed: more attacks came from remote sources via the Internet. This has led to an overwhelming number of malicious programs exploiting the IIS services – specifically a notorious buffer overflow tendency. This tendency is not operating-system-version specific, but rather configuration-specific: it depends on the services that are enabled. Following this, a common complaint is that "by default, Windows 2000 installations contain numerous potential security problems. Many unneeded services are installed and enabled, and there is no active local security policy." In addition to insecure defaults, according to the SANS Institute, the most common flaws discovered are remotely exploitable buffer overflow vulnerabilities. Other criticized flaws include the use of vulnerable encryption techniques. Code Red and Code Red II were famous (and much discussed) worms that exploited vulnerabilities of the Windows Indexing Service of Windows 2000's Internet Information Services (IIS). In August 2003, security researchers estimated that two major worms called Sobig and Blaster infected more than half a million Microsoft Windows computers. The 2005 Zotob worm was blamed for security compromises on Windows 2000 machines at ABC, CNN, the New York Times Company, and the United States Department of Homeland Security. On September 8, 2009, Microsoft skipped patching two of the five security flaws that were addressed in the monthly security update, saying that patching one of the critical security flaws was "infeasible." According to Microsoft Security Bulletin MS09-048: "The architecture to properly support TCP/IP protection does not exist on Microsoft Windows 2000 systems, making it infeasible to build the fix for Microsoft Windows 2000 Service Pack 4 to eliminate the vulnerability. To do so would require re-architecting a very significant amount of the Microsoft Windows 2000 Service Pack 4 operating system, there would be no assurance that applications designed to run on Microsoft Windows 2000 Service Pack 4 would continue to operate on the updated system." No patches for this flaw were released for the newer Windows XP (32-bit) and Windows XP Professional x64 Edition either, despite both also being affected; Microsoft suggested turning on Windows Firewall in those versions. Support lifecycle Windows 2000 and Windows 2000 Server were superseded by newer Microsoft operating systems: Windows 2000 Server products by Windows Server 2003, and Windows 2000 Professional by Windows XP Professional. The Windows 2000 family of operating systems moved from mainstream support to the extended support phase on June 30, 2005. Microsoft says that this marks the progression of Windows 2000 through the Windows lifecycle policy. Under mainstream support, Microsoft freely provides design changes if any, service packs and non-security related updates in addition to security updates, whereas in extended support, service packs are not provided and non-security updates require contacting the support personnel by e-mail or phone. Under the extended support phase, Microsoft continued to provide critical security updates every month for all components of Windows 2000 (including Internet Explorer 5.0 SP4) and paid per-incident support for technical issues. Because of Windows 2000's age, updated versions of components such as Windows Media Player 11 and Internet Explorer 7 have not been released for it. In the case of Internet Explorer, Microsoft said in 2005 that, "some of the security work in IE 7 relies on operating system functionality in XP SP2 that is non-trivial to port back to Windows 2000." While users of Windows 2000 Professional and Server were eligible to purchase the upgrade license for Windows Vista Business or Windows Server 2008, neither of these operating systems can directly perform an upgrade installation from Windows 2000; a clean installation must be performed instead or a two-step upgrade through XP/2003. Microsoft has dropped the upgrade path from Windows 2000 (and earlier) to Windows 7. Users of Windows 2000 must buy a full Windows 7 license. Although Windows 2000 is the last NT-based version of Microsoft Windows which does not include product activation, Microsoft has introduced Windows Genuine Advantage for certain downloads and non-critical updates from the Download Center for Windows 2000. Windows 2000 reached the end of its lifecycle on July 13, 2010 (alongside Service Pack 2 of Windows XP). It will not receive new security updates and new security-related hotfixes after this date. In Japan, over 130,000 servers and 500,000 PCs in local governments were affected; many local governments said that they will not update as they do not have funds to cover a replacement. As of 2011, Windows Update still supports the Windows 2000 updates available on Patch Tuesday in July 2010, e.g., if older optional Windows 2000 features are enabled later. Microsoft Office products under Windows 2000 have their own product lifecycles. While Internet Explorer 6 for Windows XP did receive security patches up until it lost support, this is not the case for IE6 under Windows 2000. The Windows Malicious Software Removal Tool installed monthly by Windows Update for XP and later versions can be still downloaded manually for Windows 2000. Microsoft in 2020 announced that it would disable the Windows Update service for SHA-1 endpoints and since Windows 2000 did not get an update for SHA-2, Windows Update Services are no longer available on the OS as of late July 2020. However, as of April 2021, the old updates for Windows 2000 are still available on the Microsoft Update Catalog. Total cost of ownership In October 2002, Microsoft commissioned IDC to determine the total cost of ownership (TCO) for enterprise applications on Windows 2000 versus the TCO of the same applications on Linux. IDC's report is based on telephone interviews of IT executives and managers of 104 North American companies in which they determined what they were using for a specific workload for file, print, security and networking services. IDC determined that the four areas where Windows 2000 had a better TCO than Linux – over a period of five years for an average organization of 100 employees – were file, print, network infrastructure and security infrastructure. They determined, however, that Linux had a better TCO than Windows 2000 for web serving. The report also found that the greatest cost was not in the procurement of software and hardware, but in staffing costs and downtime. While the report applied a 40% productivity factor during IT infrastructure downtime, recognizing that employees are not entirely unproductive, it did not consider the impact of downtime on the profitability of the business. The report stated that Linux servers had less unplanned downtime than Windows 2000 servers. It found that most Linux servers ran less workload per server than Windows 2000 servers and also that none of the businesses interviewed used 4-way SMP Linux computers. The report also did not take into account specific application servers – servers that need low maintenance and are provided by a specific vendor. The report did emphasize that TCO was only one factor in considering whether to use a particular IT platform, and also noted that as management and server software improved and became better packaged the overall picture shown could change. See also Architecture of Windows NT BlueKeep (security vulnerability) Comparison of operating systems DEC Multia, one of the DEC Alpha computers capable of running Windows 2000 beta Microsoft Servers, Microsoft's network server software brand Windows Neptune, a cancelled consumer edition based on Windows 2000 References Further reading Bolosky, William J.; Corbin, Scott; Goebel, David; & Douceur, John R. "Single Instance Storage in Windows 2000." Microsoft Research & Balder Technology Group, Inc. (white paper). Bozman, Jean; Gillen, Al; Kolodgy, Charles; Kusnetzky, Dan; Perry, Randy; & Shiang, David (October 2002). "Windows 2000 Versus Linux in Enterprise Computing: An assessment of business value for selected workloads." IDC, sponsored by Microsoft Corporation. White paper. Finnel, Lynn (2000). MCSE Exam 70–215, Microsoft Windows 2000 Server. Microsoft Press. . Microsoft. Running Nonnative Applications in Windows 2000 Professional . Windows 2000 Resource Kit. Retrieved May 4, 2005. Microsoft. "Active Directory Data Storage." Retrieved May 9, 2005. Minasi, Mark (1999). Installing Windows 2000 of Mastering Windows 2000 Server. Sybex. Chapter 3 – Installing Windows 2000 On Workstations with Remote Installation Services. Russinovich, Mark (October 1997). "Inside NT's Object Manager." Windows IT Pro. Russinovich, Mark (2002). "Inside Win2K NTFS, Part 1." Windows IT Pro (formerly Windows 2000 Magazine). Saville, John (January 9, 2000). "What is Native Structure Storage?." Windows IT Pro (formerly Windows 2000 Magazine). Siyan, Kanajit S. (2000). "Windows 2000 Professional Reference." New Riders. . Solomon, David; & Russinovich, Mark E. (2000). Inside Microsoft Windows 2000 (Third Edition). Microsoft Press. . Tanenbaum, Andrew S. (2001), Modern Operating Systems (2nd Edition), Prentice-Hall Trott, Bob (October 27, 1998). "It's official: NT 5.0 becomes Windows 2000." InfoWorld. Wallace, Rick (2000). MCSE Exam 70–210, Microsoft Windows 2000 Professional. Microsoft Press. . External links Windows 2000 End-of-Life Windows 2000 Service Pack 4 Windows 2000 Update Rollup 1 Version 2 1999 software 2000 software Products and services discontinued in 2010 IA-32 operating systems 2000

Operating System (OS)

OBDuino OBDuino is an open source trip computer design based on the Arduino platform. An OBDuino may be assembled and customised by an electronics hobbyist; it displays information such as instantaneous fuel economy (e.g. miles per gallon, L/100 km or kilometres per litre), engine tuning parameters etc. on an LCD. OBDuino utilises the On-Board Diagnostics interface found in most modern cars. Features Most OBD-II PIDs or derived values may be displayed. Common values include Fuel: cost, used or remaining, wasted while idling, consumption, measured in mpg or l/100 km Engine: load, RPM Temperatures: coolant, air intake Vehicle speed Tank distance Remaining distance that can be travelled on the current tank of fuel Throttle position Battery voltage CAN status, for CAN protocol only, display TX and RX error Displays instantaneous values, average, maximum and minimum values calculated per trip, per outing, or per tank of fuel Menu system for configuring parameters Relatively cheap compared to commercial alternatives Customisable and extendable OBDuino does not display or reset engine fault codes (which are available over the OBD interface). Design The key components of the design are: A microcontroller. One of the various AVR-based Arduino kits is typically used for this, although one of several Atmel AVR microcontrollers may be used directly in a custom OBDuino circuit. An interface to the car's management system, using the On-Board Diagnostics (OBD) connector found in most modern cars. This requires a cable and a circuit. There are several variations of this circuit depending on the particular OBD protocol implemented: ISO 9141/ISO 9141-2/ISO 14230, using Freescale MCZ33290EF CAN, using MCP2515 and MCP2551 Generic (SAE J1850 PWM & VPW/ISO 9141/ISO 9141-2/ISO 14230/CAN protocols), using an ELM327 from ELM Electronics. Although this gives a more versatile trip computer compatible with most modern vehicles, the ELM327 chip adds significant cost to the circuit and requires a significant supporting circuit for different protocols. It removes the complexity of interpreting the various OBD protocols. STN1110 which is software compatible with the ELM327. Unfortunately, this IC is not pin-compatible with the ELM327, therefore the circuit would require some changes. An LCD and three input buttons. A typical LCD is 2 rows x 16 characters or 4x20 character, based on the HD44780, with a circuit based on the mpguino circuit. Microcontroller code. This is a C++ program based on the Arduino framework, called a Sketch in Arduino terminology. This is loaded on the microcontroller over a USB or serial interface using the free Arduino integrated development environment. Many Arduino-based projects have either custom printed circuit boards available which include the AVR microcontroller (removing the need for an Arduino board), or extension boards that contain the extra circuit and that plug directly into the standard Arduino circuit board. No such PCBs are available for the OBDuino as of September 2009. Project The OBDuino project was started in 2008 based on the MPGuino project, with the desire to simplify wiring to the vehicle, instead of using the standard OBD-II socket that does not directly wire to the vehicle's fuel injection system and digital vehicle speed sensor, and to access the wide range of engine management data available using OBD. The project is centred on the discussion forum on ecomodder.com and the wiki and code hosting provided by Google code, project is released under the GPL license. The main OBDuino thread on the eccomoder forum was started by jmonroe on 1 June 2008 as a fork of MPGuino discussions. Magister posted an OBDuino announcement to the Arduino forum on 4 December 2008. As of September 2009, the OBDuino32K code credits these developers: Main coding/ISO/ELM: Frédéric (aka Magister on ecomodder.com) LCD part: Dave (aka dcb on ecomodder.com), optimized by Frédéric ISO Communication Protocol: Russ, Antony, Mike Features: Mike, Antony Bugs & Fixes: Antony, Frédéric, Mike The 32K in the obduino32K name differentiates the code targeted at the Atmega328 with 32k flash memory (i.e. Arduino 2009) version from the Atmega168 16k (Arduino 2008) version. Variations An OBDuino variant is described in the book Practical Arduino (2009) by Jonathan Oxer and Hugh Blemings. Based on the Arduino Mega, the OBDuino is extended to log GPS and OBD data to a USB stick. A Graphical OBD MPGuino graphs values such as miles per gallon and OBD-II PIDs, etc., on a 128*64 pixel LCD. OBDuino author Magister is working on a commercial prototype with a CAN-only protocol. Related alternatives Scangauge is a commercial trip computer using the OBD interface. In addition to the trip-computer-style features in OBDuino, the Scangauge also includes features for displaying and resetting engine fault codes. The mpguino is another Arduino-based trip computer, and is mainly limited to fuel usage measurement. It may be used in any vehicle which has an electric fuel injection system and digital vehicle speed sensor. The mpguino links directly to these sensors so it doesn't require an OBD2 interface. It can report instant and tank MPG, remaining miles till the tank is empty etc. The mpguino is available in kit form from several suppliers. The SuperMID is an enthusiast/hobbyist trip computer, designed originally for the Toyota Prius, although it may be used in any vehicle which has an electric fuel injection system and digital vehicle speed sensor. The SuperMID interfaces directly to the engine ECU or sensors, rather than using a standard OBDII connector. Bruce D. Lightner's entry won a 2004 Circuit Cellar design contest. Lightner's design uses an AVR microcontroller connected to an OBD-II interface to drive an analogue gauge displaying fuel consumption in mpg. This only implements the SAE J1850 VPW variant of the OBD-II protocol suite (so it only works with mostly GM cars that use VPW). An OBD II Car Computer design is described by NerdKits using their AVR-based microcontroller kit. This implements the SAE J1850 VPW variant of the OBD-II protocol suite (so it only works with certain cars that use VPW) and displays RPMs, Coolant Temperature, Vehicle Speed and Percent Throttle on an LCD. This is partly derived from Bruce D. Lightner's design. OBD2-LCD is an AVR based OBD-II trip computer, designed by Florian Schäffer. It implements the ISO 9141 and ISO 14230 (KW 2000) OBD-II variants, with design and code published and available in kit form. The new kit supports CAN (ISO 15765) too. See also Arduino Trip computer Carputer On-Board Diagnostics OBD-II PIDs ELM327 very common chip used in OBD interfaces References External links STN1110 emulates ELM327 Atmel AT90CAN microcontroller like ATmega328 with CAN support OBD II ScanTool, Linux-based open source OBD interface chips from ELM Electronics Auto parts Arduino Hacker culture

Operating System (OS)

Order management system An order management system, or OMS, is a computer software system used in a number of industries for order entry and processing. Electronic commerce and catalogers Orders can be received from businesses, consumers, or a mix of both, depending on the products. Offers and pricing may be done via catalogs, websites, or [broadcast network] advertisements. An integrated order management system may encompass these modules: Product information (descriptions, attributes, locations, quantities) Inventory available to promise (ATP) and sourcing Vendors, purchasing, and receiving Marketing (catalogs, promotions, pricing) Customers and prospects Order entry and customer service (including returns and refunds) Financial processing (credit cards, billing, payment on account) Order processing (selection, printing, picking, packing, shipping) There are several business domains which use OMS for different purposes but the core reasons remain the same: Telecom – To keep track of customers, accounts, credit verification, product delivery, billing, etc. Retail – Large retail companies use OMS to keep track of orders from customers, stock level maintenance, packaging and shipping and to synchronize orders across various channels. For example, if a customer orders online and picks up in store. Pharmaceuticals and healthcare Automotive – to keep track of parts sourced through OEMs Financial services Order management requires multiple steps in a sequential process like capture, validation, fraud check, payment authorization, sourcing, backorder management, pick, pack, ship and associated customer communications. Order management systems usually have workflow capabilities to manage this process. Financial securities Another use for Order Management Systems is as a software-based platform that facilitates and manages the order execution of securities, typically through the FIX protocol. Order Management Systems, sometimes known in the financial markets as Trade Order Management Systems, are used on both the buy-side and the sell-side, although the functionality provided by buy-side and sell-side OMS differs slightly. Typically only exchange members can connect directly to an exchange, which means that a sell-side OMS usually has exchange connectivity, whereas buy-side an OMS is concerned with connecting to sell-side firms. Buy-side vs sell-side An OMS allows firms to input orders to the system for routing to the pre-established destinations. They also allow firms to change, cancel and update orders. When an order is executed on the sell-side, the sell-side OMS must then update its state and send an execution report to the order's originating firm. An OMS should also allow firms to access information on orders entered into the system, including detail on all open orders and on previously completed orders. The development of multi-asset functionality is a pressing concern for firms developing OMS software. The Order Management System supports Portfolio Management by translating intended Asset Allocation actions into marketable orders for the buy-side. This typically falls into four categories: Re-balance – The periodic reallocation of a fund's asset allocation / market exposures to correct for market valuation fluctuations and cash flows Tracking – Periodic adjustment to align an Index Fund or SMA with its target Discretionary – Adhoc reallocation initiated by Portfolio Managers and Analysts Tactical Asset Allocation – Reallocation made to capture temporary inefficiencies TAA How an OMS works Changes in positional allocation often affect multiple accounts creating hundreds or thousands of small orders, which are typically grouped into aggregate market orders and crossing orders to avoid the legitimate fear of front running. When reallocation involves contradictory operations, trade crossing can sometimes be done. Crossing orders involve moving shares and cash between internal accounts, and then potentially publishing the resulting "trade" to the listing exchange. Aggregate orders, on the other hand, are traded together. The details of which accounts are participating in the market order are sometimes divulged with the trade (OTC trading) or post-execution (FIX and/or through the settlement process.) In some circumstances, such as equities in the United States, an average price for the aggregate market order can be applied to all of the shares allocated to the individual accounts which participated in the aggregate market order. In other circumstances, such as Futures or Brazilian markets, each account must be allocated specific prices at which the market order is executed. Identifying the price that an account received from the aggregate market order is regulated and scrutinized post-trade process of trade allocation. An additional wrinkle to the trade allocation process is that aggregate market order may not be fully satisfied. If, for example, a limit order is used to control slippage, then it may take weeks to fully implement a discretionary asset allocation change. This adds a participation fairness issue in trade allocation in addition to price fairness. The two aspects are compound since the market may move against your position under the pressure of your large pending aggregate market order (even if implemented as a dark-pool Program Trade.) Some Order Management Systems go a step further in their trade allocation process by providing tax lot assignment. Because investment managers are graded on unrealized profit & loss, but the investor needs to pay capital gains on realized profit & loss; it is often beneficial for the investor that the exact share/contract uses in a closing trade be carefully chosen. For example, selling older shares rather than newly acquired shares may reduce the effective tax rate. This information does not need to be finalized until capital gains are to be paid or until taxes are to be filed, OMS tax lot assignments are considered usually tentative. The tax lot assignments remade or recorded within the Accounting System are considered definitive. Compliance An OMS is a data-rich source of information which is able to communicate to the front and back office systems (or modules in the case of a single platform software). Prices, number of shares, volumes, date, time, financial instrument, share class, exchange are all key data values which allows the asset/investment manager to maintain an accurate and true positional view of their portfolio ensures all investment guidelines are met and any potential breaches are avoided or resolved in a timely manner. Guidelines between the investor and investment manager are stated in the Investment Policy Statement, IPS, and can be understood as constraints on the asset allocation of the portfolio to ensure the manager does not drift from the stated investment strategy over time at an attempt of TAA. For example, an agreed guideline may include a set portion of the portfolio should constitute of cash and cash equivalents to maintain liquidity levels. Reporting An outcome of an OMS successfully communicating to an asset manager's systems is the ease of producing accurate and timely reporting. All data can be seamlessly interpreted to create valuable information about the portfolio's performance and composition, as well as investment activities, fees and cash flows to a granular level. As investors are demanding increasingly detailed and frequent reporting, an asset manager can benefit from the correct set up of an OMS to deliver information whilst focusing on core activities. Increasing financial regulations are also causing managers to allocate more resources to ensure firstly, they are able to obtain the correct data on their trades and then they are compliant to the new metrics. For example, if a predetermined percent of the portfolio can hold a certain asset class or risk exposure to the asset class or market, the investment manager must be able to report this was satisfied during the reporting period. Types Order management systems can be standalone systems like Multiorders or modules of an ERP system such as Megaventory, Ordoro, Fishbowl or Cloud Commerce Pro. Another difference is whether the system is an on-premises software or a cloud-based software. Their basic difference is that the on-premises ERP solutions are installed locally on a company's own computers and servers and managed by their own IT staff, while a cloud software is hosted on the vendor's servers and accessed through a web browser. Order management systems for financial securities can also be used as a standalone system or modules of a PMS system, to process trade orders simultaneously across a number of funds, the IT infrastructure lowers operational risk. See also Execution management system Order fulfillment Purchase order Sales order References Enterprise resource planning terminology Electronic trading systems

Operating System (OS)

System 10 System 10 or System Ten may refer to: Computing DECsystem-10, the mainframe line by Digital Equipment Corporation Singer System 10, the business minicomputer IBM System z10, the mainframe line by IBM Namco System 10, the arcade system board Tandy 10 Business Computer System, the business minicomputer Operating systems Android 10, the Google operating system BlackBerry 10, the BlackBerry operating system Linux operating system distributive versions: Debian 10, the Debian Project distributive (2019) Fedora 10, the RedHat-based distributive (2008) Gentoo 10, she special release of Gentoo distributive (2009) Mandriva 10, the Mandriva distributive (2004) Mint 10, the Ubuntu-based distributive (2010) openSUSE 10, the openSUSE Project distributive (2005) Ubuntu 10.4 and Ubuntu 10.10, the Canonical distributive (2010) Mac OS X 10, the Apple operating system TOPS-10, the Digital Equipment Corporation operating system FTOS, the Force10 operating system FreeBSD 10, the FreeBSD Project operating system Version 10 Unix, the last version of the original Unix of Bell Labs Windows 10, the Microsoft operating system Sports 10-point must system, the boxing strategy Perfect 10 (gymnastics), the scoring system Other Base-ten number system, the decimal numeral system ICD-10 Procedure Coding System, the system of medical classification Pentax System 10, the Pentax single-lens camera STS-10 (Space Transportation System-10), a cancelled Space Shuttle mission See also System X (disambiguation) OS 10

Operating System (OS)

TRSDOS TRSDOS (which stands for the Tandy Radio Shack Disk Operating System) is the operating system for the Tandy TRS-80 line of eight-bit Zilog Z80 microcomputers that were sold through Radio Shack from 1977 through 1991. Tandy's manuals recommended that it be pronounced triss-doss. TRSDOS should not be confused with Tandy DOS, a version of MS-DOS licensed from Microsoft for Tandy's x86 line of personal computers (PCs). With the original TRS-80 Model I of 1977, TRSDOS was primarily a way of extending the MBASIC (BASIC in ROM) with additional I/O (input/output) commands that worked with disk files rather than the cassette tapes that were used by non-disk Model I systems. Later disk-equipped Model III computers used a completely different version of TRSDOS by Radio Shack which culminated in 1981 with TRSDOS Version 1.3. From 1983 disk-equipped TRS-80 Model 4 computers used TRSDOS Version 6, which was a development of Model III LDOS by Logical Systems, Inc. This last was updated in 1987 and released as LS-DOS 6.3. Completely unrelated was a version of TRSDOS by Radio Shack for its TRS-80 Model II professional computer from 1979, also based on the Z80 and equipped with 8-inch disk drives. The later machines in this line, the Models 12, 16 and 6000, used the Z80 as an alternate CPU to its main Motorola 68000 chip and could run this version of TRSDOS for backwards compatibility with older Z80 applications software. History Tandy Corporation's TRS-80 microcomputer did not have a disk drive or disk operating system at release. The first version of TRSDOS, by Randy Cook, was so buggy that others wrote alternatives, including NewDOS and LDOS. After disputes with Cook over ownership of the source code, Tandy hired Logical Systems, LDOS's developer, to continue TRSDOS development. TRSDOS 6, shipped with the TRS-80 Model 4 in 1983, is identical to LDOS 6.00. Dates May 8, 1979 – Radio Shack releases TRSDOS 2.3 May 1, 1981 – Radio Shack releases Model III TRSDOS 1.3 April 26, 1983 – Radio Shack introduces TRSDOS Version 6.0 with the new Model 4s 1984 – Radio Shack releases Version 6.2, the definitive version for the Model 4 1984 – Logical Systems publishes The Source, the commented assembler source code to TRSDOS 6.2 Late 1986 – Logical Systems releases LS-DOS 6.3, the functionally equivalent update to TRSDOS 6.2. From this date, Tandy/Radio Shack ships it with the Model 4D. Features and capabilities RadioShack's Z80-based line of TRS-80 computers (Models I/III and Model 4) support up to four physical floppy (mini-diskette) drives which (as sold) use 5¼-inch diskettes. The original TRSDOS for the Model I supported only single-sided disks with 35 tracks formatted in single density (sectors are encoded using the frequency modulation technique). Model III TRSDOS (culminating in version 1.3) supported 40-track disks formatted in double density (using modified frequency modulation). Model Is retrofitted with double density controllers and Models I/III equipped with 80-track drives or double-sided drives could not use TRSDOS; RadioShack sold Logical System's LDOS operating system which could control these types of drives. The Model 4's TRSDOS 6 is a development of LDOS and has the same capabilities. Hard disk drives (then also known as winchester drives) required custom driver software supplied by their manufacturers. These drivers permitted any TRSDOS installation to access them with up to eight possible drive partitions, each assigned to drive numbers zero through seven. Actually, a large hard drive could be formatted with more than eight partitions, but TRSDOS can only access eight during any one session. Hard drives could have some partitions formatted under TRSDOS and others under the CP/M OS. Each floppy drive in the system would also take up one drive number assignment. The Model 4, with its ability to set up a ramdisk (Memdisk), also required a drive number assignment for this. All versions of TRSDOS use overlays to satisfy most system requests and disk directories are not maintained in memory. This has two implications for system performance. First, upon initial file access the DOS always references the disk directory to obtain information giving the physical mapping of disk space allocated to the file (including its extents, if any). After the initial access this information is maintained in a File Control Block, the memory space for which is supplied by the calling application. Further references do not need to read the disk directory (unless the file is written to and more disk space needs to be allocated). For this reason system performance depends greatly on how close a file's allocated disk space(s) is/are to the directory cylinder, and how fragmented (extents located in non-contiguous space(s)) the file is as a whole. The farther away the directory cylinder is, the more the drive's read/write head will need to move, which slows disk access and produces more mechanical wear on the drive. TRSDOS has commands permitting the user to optimize placement of particular files on the disk's physical space, and the command to display a map of a file's physical placement on a drive. The second implication of the overlay-based architecture is that a disk containing TRSDOS system files (file extension /SYS) must always be present in whichever drive is assigned as logical drive number zero. (On the Model 4 this may be the Memdisk, thus freeing physical drive zero be used for a non-system data disk). LDOS and TRSDOS 6 have a SYSRES command which loads selected system files into Z80 RAM, thus freeing space on the system disk for non-system data. All versions have variants of the SYSTEM command which can reassign logical drive numbers to physical drives. It is possible to assign drive numbers such that a physical drive is unassigned a logical drive number; this is sometimes useful to guarantee that the drive cannot be accessed for security or safety (write protection) purposes. Drives may be set to be write protected by the DOS, also. Disk management The primary function of any disk operating system is to provide the user with a facility for managing and accessing files stored on disk storage devices. Since the user must not be burdened with the physical details of the storage devices themselves, it is the operating system's responsibility to translate file record access requests into specific drive, track, sector, and head parameters that pinpoint the storage location of each record. The system also maintains in Z80 memory within TRSDOS a Drive Control Table that stores the parameters associated with each of the eight logical drives. Disk drive parameters refer to how the total storage space on a drive is divided up into addressable units. The layer(s) of magnetic particles on the surface of the disk media are magnetized (during the format process) into concentric circles of storage areas called TRACKS. Each track is divided into 256-byte sub-areas called SECTORS. Each sector is uniquely identified by a pattern of information preceding each sector called an ID FIELD. Although the number of sectors per track may vary from one media type to another, the number of sectors in each track of the same media (and in each granule) must always be a constant. Disks are organized as follows: each track is formatted into a specific number of 256-byte sectors with a maximum capacity of 32 sectors per track. Sectors are grouped into blocks called granules which vary in size according to total track capacity of the disk media, though granule size for each disk format is constant. For forty-cylinder disks formatted in double density, standard for the drives installed in the TRS-80 Models III and 4, the granule size is six 256-byte sectors, or 1.5 KB. Each track has three granules for 4.5 KB of storage. Each side (surface) of the disk is normally formatted with 40 tracks, yielding 180 KB per side. The Model 4D, with its double-sided drives, yields 360 KB of storage. Whenever additional disk space is needed for a file (such as extending a file while being written to), an additional granule is allocated. The granule thus becomes the minimum size storage unit. TRSDOS assigns numbers to every sector, every track, and every surface. Surfaces are numbered consecutively starting from zero. Tracks are numbered consecutively starting from zero at the outermost edge of the disk giving the innermost track the highest number. Where multiple headed drives are in use, the track numbers on a surface are duplicated on each surface with all similarly numbered tracks constituting a cylinder. For a double-sided floppy disk as formatted on a Model 4D, track zero of surface zero and track zero of surface one are grouped together into cylinder zero. Cylinder capacities also have an upper limit of 256 sectors per cylinder or eight granules per cylinder, while the system supports (for hard drives with multiple platters of storage media) a maximum of eight heads per drive. The disk's directory cylinder is placed during the format process on the middle-numbered cylinder; thus a standard 40 cylinder disk has its directory installed on cylinder 20. This reduces the average distance (and access time) that the drive's read/write head must move to access the directory. The first sector of the disk directory contains the Granule Allocation Table (GAT). The GAT is bit mapped to each granule of space on the drive. Other fields in the GAT contain the PACK NAME, DATE of creation (when the disk was formatted), pack PASSWORD, and data pertaining to the configuration of the drive. When a file is to be opened for access, the system needs to search the directory for its directory record. Search time is minimized by using a hashing technique to reduce the 11-character string formed from the file name and extension to a one byte value. The hash code for each file is stored in a Hash Index Table (HIT) which is the second sector of the directory. Each position in this table corresponds to a specific directory entry record. The hash table, being one sector in length, can index a maximum of 256 directory records or files. The directory itself is sized according to disk capacity by being a maximum of one cylinder (up to 34 sectors). Thus, the larger the disk storage capacity, the larger its directory, and the greater the number of file names that can be stored on the disk. The directory record contains information such as the date the file was last modified, its update and access password codes, its access level, and other attributes such as whether it is a SYStem or PDS (Partitioned Data Set) file and if a backup has been made, the relative number of the last sector in the file, and the last byte within the last sector (or End Of File). The record also contains the physical area(s) in use by the file, by pointing to the cylinder, relative starting granule, and number of contiguous granules for each extent comprising the file. When a file has more than four extents, additional directory records are used as required with forward and backward pointers linking each record of each file. Thus the theoretical maximum of 256 files possible on a floppy diskette is realizable only if there is no file fragmentation. When TRSDOS formats a disk, all of the parameters associated with the diskette are predetermined. Thus the number of sectors per track, number of sectors per granule and thus the granules per track, number of sides (surfaces), and number of cylinders are all designated, as well as the density of the media. Some of these figures (density, sides, granules per track) are written to fields in the Granule Allocation Table which is part of the disk directory. Others (sectors per track, sectors per granule, in addition to the former quantities) are part of the Drive Control Table fields. When the system attempts to open a file on a disk, it uses the @CKDRV SVC to ascertain the availability of the disk, and then logs the disk once it finds it available. This "logging" function will update the DIRCYL field, then update the DBLBIT and MAXCYL fields based on information stored in the GAT. This procedure frees the user from having to manually log a newly inserted disk; he is at liberty to change differently formatted disks in any drive without concern that the system will incorrectly access it. The SVC disk primitives are funneled through common system routines contained in the driver software installed for each type of disk storage device. The driver for Model III or Model 4 floppy drives is named "$FD" and is located in the TRSDOS low memory region. Hard disk drives are supplied with their own driver software, and are usually installed in high memory (main 64K Z80 RAM) above the system HIGH$ pointer, since room in the low memory region is usually insufficient (especially on the Model 4 since software needed to access its external memory banks cannot reside in high Z80 RAM memory because that region exists in the banked RAM swap area). These driver routines establish a linkage protocol between the application requesting disk access and the computer's Floppy Disk Controller hardware. TRS-80s use controller chips from the Western Digital series: the WD1791 in the Model 4 non-gate array version, and the WD1773 in the Model 4 Gate Array version. When an I/O request is invoked by a higher level SVC, such as a request to READ a file record, the request is translated to that disk primitive (FDC command or status report) needed to satisfy the function request. The linkage protocol is uniform across all disk devices that are connected to the system. This makes the access of files transparent to size or nature of the disk device within the scope of the parameters stored in the DCT for that drive. File management Disk files are supported with two types of access: Record I/O and character I/O. Logical records of from one to 256 bytes in length can be read or written using the @READ or @WRITE SVC requests. Record I/O can be random access (by position SVC requests prior to READ/WRITE) or sequential access using repetitive READs or WRITEs. Character (or byte) I/O is accomplished by @GET and @PUT SVC requests and is essentially the same as record I/O with a Logical Record Length (LRL) equal to one. (Physical access to a disk storage device is always in units of 256 byte sectors. This is fixed by the TRS-80 disk controller hardware). However, if GET or PUT are used to implement sequential access, then a file can be considered a character I/O device just like a printer, a serial port, or a video display device. A byte I/O request is therefore independent of the physical device "connected" to the control block which is requesting the I/O. This makes the system "device independent". Filenames are limited to eight alphanumeric characters (the first character must be alpha) which are case insensitive (only capital letters are used; any lowercase letters entered are capitalized). File extensions are up to three characters and obey the same rules. File passwords are up to eight characters obeying the same rules (TRSDOS 6 versions up to 6.2 support both owner and user passwords). Entire diskettes can also be assigned master passwords, which may limit user access via the BACKUP and PURGE commands. Under TRSDOS and LDOS the system is never "logged in" to any current drive as with CP/M, PC DOS and MS-DOS. The system prompt is always . All file access requests (whether issued by the user at the console or a program being executed) are satisfied by searching the directory of the first drive specified (taken as drive zero if no drive number is given) and, if the requested file is not found, then searching the next (higher numbered) drive in the system. This continues until the file is found or all the drives in the system have been searched (but see below for variations on this rule). Drive numbers are specified with a colon followed immediately with the drive number. The colon is optional unless the drive specification is used as a suffix for a filename. Using the directory command as an example: displays all files starting with logical drive zero, then drive one, and so on. or searches logical drive four (for all files, as always when no filename is given). or searches logical drives four, five, and six. or searches logical drives four, five, six and seven. searches for FILENAME on logical drive two. searches for FILENAME on all logical drives starting from drive two. As seen, the dash character is used to specify a range of drive numbers. The and (catalog) commands display all file specifications (filespecs) matching the query on all drives. Other commands/utilities such as , and , and drive searches initiated by programs being executed, stop searching at the first drive found to match. If the same filespec exists on multiple drives, then those files on higher-numbered drives will be excluded. File access by partial filenames (partspecs), file extensions, and file dates are supported. For example: will select files SAMPLE, SAMPLE1, SAMPLE23 and SAMPLEIT. will select files SAMPLE/BAS, TEST/BAS, EXAMPLE/BAS, etc. As with the example earlier, drive specifications (drivespecs) may be appended to filespecs. These examples assume the selected files have not be made invisible in the disk directory. File access requests issued by applications programs running under TRSDOS work the same way. Command-line interface Under TRSDOS/LS-DOS 6.x, the standard system command interpreter (SYS1/SYS) can be functionally replaced with a custom interpreter by copying the new interpreter to the system file SYS13/SYS (which in an unmodified installation is a dummy file). This can be any machine code /CMD program file. This is referred to in the documentation as an "Extended Command Interpreter" or ECI. TRSDOS/LS-DOS 6.x support wildcard characters in filenames, both the single character ? and multicharacter *. TRSDOS (version II) was notable for the inclusion of noise words, similar to the 1959 COBOL specification. These made commands more English-like. For example, the following commands functioned identically: COPY filea fileb COPY filea TO fileb Since TRSDOS does not have the notion of redirection for disk files as UNIX/Linux and MS-DOS do, the APPEND command is somewhat different in concept than the UNIX or MS-DOS notion of appending via output redirection. TRSDOS/LS-DOS 6.x do provide I/O redirection for system devices (keyboard *KI, display screen *DO, printer *PR, serial port *CL), as well as for between devices and disk files. The DEVICE command displays a map of I/O links and routes. Under DOS and UNIX printing a file can be done with redirection; under UNIX it is normally done by spooling the file to the "line printer" (using the lpr command) because UNIX is conventionally a multi-user system. TRSDOS/LS-DOS 6.x print jobs can be redirected (such as to a disk file) by applying the LINK or ROUTE commands to the system *PR device. TRSDOS/LS-DOS 6.x do not support subdirectories or user areas. However, the DIR and CAT (Catalog) commands for displaying file data support the usual partial filenames, suffixes, and file dates. Under TRSDOS/LS-DOS 6.x files can be made invisible to the DIR and CAT commands, and can be displayed with the INV parameter (unless any files are password protected and the correct p/w is not given). TRSDOS/LS-DOS 6.3 can dump the video screen to the line printer by pressing . Many versions support a simple password security for files and programs, with separate Read/Execute and full access capabilities. ex: filename/ext.password:drive#. TRSDOS 6.x supports both Owner and User passwords (8 characters max) for disk files. LS-DOS 6.3 uses the space for the User password for its extended dating scheme (past December 31, 1987). Both Model 4 OSes can set various file access levels and permit software write protection for disk files and entire disks. Commands Although MS-DOS owes its heritage most closely to CP/M and thence to TOPS-10, many of the file manipulation commands are similar to those of TRSDOS. Some of the following TRSDOS commands exist on disk as distinct program files (DIR/CMD, FORMAT/CMD, BACKUP/CMD) while all others exist as modules condensed into the library files (technically Partitioned Data Sets or PDSs) SYS6/SYS, SYS7/SYS and SYS8/SYS; these include the TRSDOS commands CAT, COPY, LIST, REMOVE, RENAME etc. Some typical TRSDOS utilities: References External links TRSDOS/LS-DOS 6.x user command summary TRS-80 Error Messages TRS-80 Revived Site Model III Home Page (with list of TRSDOS alternatives on the TRS-80 Model III) Matthew Reed's TRS-80 Emulator Software Runs under MS-DOS; requires the extraction of a ROM image xtrs A TRS-80 emulator for UNIX and X11; similar ROM issues apply TRSdisk, TRSDOS utilities for UNIX TRS-80 Virtual Floppy Disk Manager TRSDOS Applications Disk operating systems TRS-80 Discontinued operating systems 1977 software

Operating System (OS)

Macintosh The Macintosh (mainly Mac since 1998) is a family of personal computers designed, manufactured, and sold by Apple Inc. (originally as Apple Computer, Inc.) since January 1984. The original Macintosh is the first successful mass-market all-in-one desktop personal computer to have featured a graphical user interface, built-in screen, and mouse. Apple sold the Macintosh alongside its popular Apple II, Apple IIGS, Apple III, and Apple Lisa families of computers until the other models were discontinued in the 1990s. Early Macintosh models were relatively expensive, hindering competitiveness in a market dominated by the much cheaper Commodore 64 for consumers, as well as the IBM Personal Computer and its accompanying clone market for businesses, although they were less expensive than the Xerox Alto and other computers with graphical user interfaces that predated the Mac, except Atari ST. Macintosh systems were successful in education and desktop publishing, making Apple the second-largest PC manufacturer for the next decade. In the early 1990s, Apple introduced the Macintosh LC II and Color Classic which were price-competitive with Wintel machines at the time. However, the introduction of Windows 3.1 and Intel's Pentium processor, which beat the Motorola 68040 used in then-current Macintoshes in most benchmarks, gradually took market share from Apple, and by the end of 1994 Apple was relegated to third place as Compaq became the top PC manufacturer. Even after the transition to the superior PowerPC-based Power Macintosh line in the mid-1990s, the falling prices of commodity PC components, poor inventory management with the Macintosh Performa, and the release of Windows 95 contributed to continued decline of the Macintosh user base. Upon his return to the company, Steve Jobs led Apple to consolidate the complex line of nearly twenty Macintosh models in mid-1997 (including models made for specific regions) down to four in mid-1999: the Power Macintosh G3, iMac G3, 14.1" PowerBook G3, and 12" iBook. All four products were critically and commercially successful due to their high performance, competitive prices, and aesthetic designs, and helped return Apple to profitability. Around this time, Apple phased out the Macintosh name in favor of "Mac", a nickname that had been in common use since the development of the first model. After their transition to Intel processors in 2006, the complete lineup was Intel-based. This changed in 2020 when the M1 chip was introduced to the MacBook Air, entry level MacBook Pro and Mac Mini. Its current lineup includes three desktops (the all-in-one iMac and the desktop Mac Mini and Mac Pro), and two notebooks (the MacBook Air and MacBook Pro). Its Xserve server was discontinued in 2011 in favor of the Mac Mini and Mac Pro. Apple has developed a series of Macintosh operating systems. The first versions initially had no name but came to be known as the "Macintosh System Software" in 1988, "Mac OS" in 1997 with the release of Mac OS 7.6, and retrospectively called "Classic Mac OS". Apple produced a Unix-based operating system for the Macintosh called A/UX from 1988 to 1995, which closely resembled contemporary versions of the Macintosh system software. Apple does not license macOS for use on non-Apple computers, however, System 7 was licensed to various companies through Apple's Macintosh clone program from 1995 to 1997. Only one company, UMAX Technologies, was legally licensed to ship clones running Mac OS 8. In 2001, Apple released Mac OS X, a modern Unix-based operating system which was later rebranded to simply OS X in 2012, and then macOS in 2016. Its final version was macOS Catalina, as Apple went on to release macOS Big Sur in 2020. The current version is macOS Monterey, first released on June 7, 2021. Intel-based Macs can run native third party operating systems such as Linux, FreeBSD, and Microsoft Windows with the aid of Boot Camp or third-party software. (The same feat has been accomplished on ARM-based Apple silicon, but it requires an operating system built for it.) Volunteer communities have customized Intel-based macOS to run illicitly on non-Apple computers. The Macintosh family of computers has used a variety of different CPU architectures since its introduction. Originally they used the Motorola 68000 series of microprocessors. In the mid-1990s they transitioned to PowerPC processors, and again in the mid-2000s they began to use 32- and 64-bit Intel x86 processors. Apple began transitioning CPU architectures to its own ARM based Apple silicon for use in the Macintosh beginning in 2020. Etymology The Macintosh project began in 1979 when Jef Raskin, an Apple employee, envisioned an easy-to-use, low-cost computer for the average consumer. He wanted to name the computer after his favorite type of apple, the McIntosh ( ), but the spelling was changed to "Macintosh" for legal reasons as the original was the same spelling as that used by McIntosh Laboratory, Inc., an audio equipment manufacturer. Steve Jobs requested that McIntosh Laboratory give Apple a release for the newly spelled name, thus allowing Apple to use it. The request was denied, forcing Apple to eventually buy the rights to use this name. A 1984 Byte magazine article suggested Apple changed the spelling only after "early users" misspelled "McIntosh". However, Jef Raskin had adopted the "Macintosh" spelling by 1981, when the Macintosh computer was still a single prototype machine in the lab. History 1978–84: Development and introduction In 1978 Apple began to organize the Apple Lisa project, aiming to build a next-generation machine similar to an advanced Apple II or the yet-to-be-introduced IBM PC. In 1979 Steve Jobs learned of the advanced work on graphical user interfaces (GUI) taking place at Xerox PARC. He arranged for Apple engineers to be allowed to visit PARC to see the systems in action. The Apple Lisa project was immediately redirected to use a GUI, which at that time was well beyond the state of the art for microprocessor abilities; the Xerox Alto required a custom processor that spanned several circuit boards in a case which was the size of a small refrigerator. Things had changed dramatically with the introduction of the 16/32-bit Motorola 68000 in 1979, which offered at least an order of magnitude better performance than existing designs and made a software GUI machine a practical possibility. The basic layout of the Lisa was largely complete by 1982, at which point Jobs's continual suggestions for improvements led to him being kicked off the project. At the same time that the Lisa was becoming a GUI machine in 1979, Jef Raskin began the Macintosh project. The design at that time was for a low-cost, easy-to-use machine for the average consumer. Instead of a GUI, it intended to use a text-based user interface that allowed several programs to be running and easily switched between, and special command keys on the keyboard that accessed standardized commands in the programs. Raskin was authorized to start hiring for the project in September 1979, and he immediately asked his long-time colleague, Brian Howard, to join him. His initial team would eventually consist of himself, Howard, Joanna Hoffman, Burrell Smith, and Bud Tribble. The rest of the original Mac team would include Bill Atkinson, Bob Belleville, Steve Capps, George Crow, Donn Denman, Chris Espinosa, Andy Hertzfeld, Bruce Horn, Susan Kare, Larry Kenyon, and Caroline Rose with Steve Jobs leading the project. In a 2013 interview, Steve Wozniak insinuated that he had been leading the initial design and development phase of the Macintosh project until 1981 when he experienced a traumatic airplane crash and temporarily left the company, at which point Jobs took over. In that same interview, Wozniak said that the original Macintosh "failed" under Jobs and that it was not until Jobs left that it became a success. He attributed the eventual success of the Macintosh to people like John Sculley "who worked to build a Macintosh market when the Apple II went away". Smith's first Macintosh board was built to Raskin's design specifications: it had 64 kilobytes (kB) of random-access memory (RAM), used the 8-bit Motorola 6809E microprocessor, and could support a 256×256-pixel black and white raster graphics (bitmap) display. Bud Tribble, a member of the Mac team, was interested in running the Apple Lisa's graphical programs on the Macintosh and asked Smith whether he could incorporate Lisa's 68000 microprocessor into the Mac while still keeping the production cost down. By December 1980, Smith had succeeded in designing a board that not only used the 68000 but increased its speed from Lisa's 5 MHz to 8 MHz; this board also had the capacity to support a 384×256-pixel display. Smith's design used fewer RAM chips than the Lisa, which made the production of the board significantly more cost-efficient. The final Mac design was self-contained and had the complete QuickDraw picture language and interpreter in 64 KB of ROM – far more than most other computers which typically had around 4 to 8 KB of ROM; it had 128 kB of RAM, in the form of sixteen 64-kilobit (kb) RAM chips soldered to the logicboard. Although there were no memory slots, its RAM was expandable to 512 kB by means of soldering sixteen IC sockets to accept 256 kb RAM chips in place of the factory-installed chips. The final product's screen was a , 512x342 pixel monochrome display, exceeding the size of the planned screen. Burrell's innovative design, combining the low production cost of an Apple II with the computing power of Lisa's Motorola 68000 CPU, began to receive Jobs's attentions. InfoWorld in September 1981 reported on the existence of the secret Lisa and "McIntosh" projects at Apple. Stating that they and another computer "are all scheduled to be ready for release within a year", it described McIntosh as a portable computer with the 68000 and 128KB memory, and possibly battery-powered. Realizing that the Macintosh was more marketable than the Lisa, Jobs began to focus his attention on the project. Raskin left the team in 1981 over a personality conflict with Jobs. After development had completed, team member Andy Hertzfeld said that the final Macintosh design is closer to Jobs's ideas than Raskin's. When Jobs was forced out of the Lisa team in 1982, he devoted his entire attention to the Macintosh. Jobs commissioned industrial designer Hartmut Esslinger to work on the Macintosh line, resulting in the "Snow White" design language; although it came too late for the earliest Macs, it was implemented in most other mid- to late-1980s Apple computers. 1984: Debut In 1982 Regis McKenna was brought in to shape the marketing and launch of the Macintosh. Later the Regis McKenna team grew to include Jane Anderson, Katie Cadigan and Andy Cunningham, who eventually led the Apple account for the agency. Cunningham and Anderson were the primary authors of the Macintosh launch plan. The launch of the Macintosh pioneered many different tactics that are used today in launching technology products, including the "multiple exclusive," event marketing (credited to John Sculley, who brought the concept over from Pepsi), creating a mystique about a product and giving an inside look into a product's creation. After the Lisa's announcement, John Dvorak discussed rumors of a mysterious "MacIntosh" project at Apple in February 1983. The company announced the Macintosh 128K—manufactured at an Apple factory in Fremont, California—in October 1983, followed by an 18-page brochure included with various magazines in December. The Macintosh was introduced by a US$1.5 million Ridley Scott television commercial, "1984". It aired during the third quarter of Super Bowl XVIII on January 22, 1984, and is now considered a "watershed event" and a "masterpiece". McKenna called the ad "more successful than the Mac itself." "1984" used an unnamed heroine to represent the coming of the Macintosh (indicated by a Picasso-style picture of the computer on her white tank top) as a means of saving humanity from the "conformity" of IBM's attempts to dominate the computer industry. The ad alludes to George Orwell's novel Nineteen Eighty-Four which described a dystopian future ruled by a televised "Big Brother." Two days after "1984" aired, the Macintosh went on sale, and came bundled with two applications designed to show off its interface: MacWrite and MacPaint. It was first demonstrated by Steve Jobs in the first of his famous Mac keynote speeches, and though the Mac garnered an immediate, enthusiastic following, some labeled it a mere "toy." Because the operating system was designed largely for the GUI, existing text-mode and command-driven applications had to be redesigned and the programming code rewritten. This was a time-consuming task that many software developers chose not to undertake, and could be regarded as a reason for an initial lack of software for the new system. In April 1984, Microsoft's MultiPlan migrated over from MS-DOS, with Microsoft Word following in January 1985. In 1985 Lotus Software introduced Lotus Jazz for the Macintosh platform after the success of Lotus 1-2-3 for the IBM PC, although it was largely a flop. Apple introduced the Macintosh Office suite the same year with the "Lemmings" ad. Infamous for insulting its own potential customers, the ad was not successful. Apple spent $2.5 million purchasing all 39 advertising pages in a special, post-election issue of Newsweek, and ran a "Test Drive a Macintosh" promotion, in which potential buyers with a credit card could take home a Macintosh for 24 hours and return it to a dealer afterwards. While 200,000 people participated, dealers disliked the promotion, the supply of computers was insufficient for demand, and many were returned in such a bad condition that they could no longer be sold. This marketing campaign caused CEO John Sculley to raise the price from $1,995 to $2,495 (). The computer sold well, nonetheless, reportedly outselling the IBM PCjr which also began shipping early that year; one dealer reported a backlog of more than 600 orders. By April 1984 the company sold 50,000 Macintoshes, and hoped for 70,000 by early May and almost 250,000 by the end of the year. 1984–90: Desktop publishing Most Apple II sales had once been to companies, but the IBM PC caused small businesses, schools, and some homes to become Apple's main customers. Jobs stated during the Macintosh's introduction "we expect Macintosh to become the third industry standard", after Apple II and IBM PC. Macintosh at first outsold every other computer; it was so compelling that one dealer described it as "the first $2,500 impulse item". The computer nonetheless did not meet expectations during the first year, especially among business customers. Only about ten applications including MacWrite and MacPaint were widely available, although many non-Apple software developers participated in the introduction and Apple promised that 79 companies including Lotus, Digital Research, and Ashton-Tate were creating products for the new computer. After one year for each computer, the Macintosh had less than one-quarter of the PC's software selection—including one word processor, two databases, and one spreadsheet—although Apple had sold 280,000 Macintoshes compared to IBM's first-year sales of fewer than 100,000 PCs. MacWrite's inclusion with the Macintosh discouraged developers from creating other word processing software. Although Macintosh excited software developers—Doug Carlston said that Broderbund programmers fought over their Macintosh while PCjr was "in some closet"—they were required to learn how to write software that used the graphic user interface, and early in the computer's history needed a Lisa 2 or Unix system to write Macintosh software. Infocom had developed the only third-party games for the Mac's launch by replacing the buggy early operating system with the company's own minimal bootable game platform. Despite standardizing on Pascal for software development Apple did not release a native-code Pascal compiler. Until third-party Pascal compilers appeared, developers had to write software in other languages while still learning enough Pascal to understand Inside Macintosh. The Macintosh 128K, originally released as the Apple Macintosh, is the original Apple Macintosh personal computer. Its beige case consisted of a 9 in (23 cm) CRT monitor and came with a keyboard and mouse. A handle built into the top of the case made it easier for the computer to be lifted and carried. This was synonymous with the release of the iconic 1984 TV Advertisement by Apple. This model and the 512k released in September of the same year had signatures of the core team embossed inside the hard plastic cover and soon became collector pieces. In 1985 the combination of the Mac, Apple's LaserWriter printer, and Mac-specific software like Boston Software's MacPublisher and Aldus PageMaker enabled users to design, preview, and print page layouts complete with text and graphics—an activity to become known as desktop publishing. Initially, desktop publishing was unique to the Macintosh, but eventually became available for other platforms. Later, applications such as Macromedia FreeHand, QuarkXPress, and Adobe's Photoshop and Illustrator strengthened the Mac's position as a graphics computer and helped to expand the emerging desktop publishing market. The Macintosh's minimal memory became apparent, even compared with other personal computers in 1984, and could not be expanded easily. It also lacked a hard disk drive or the means to easily attach one. Many small companies sprang up to address the memory issue. Suggestions revolved around either upgrading the memory to 512 KB or removing the computer's 16 memory chips and replacing them with larger-capacity chips, a tedious and difficult operation. In October 1984 Apple introduced the Macintosh 512K, with quadruple the memory of the original, at a price of US$3,195. It also offered an upgrade for 128k Macs that involved replacing the logic board. Apple released the Macintosh Plus on January 10, 1986, for a price of US$2,600. It offered one megabyte of RAM, easily expandable to four megabytes by the use of socketed RAM boards. It also featured a SCSI parallel interface, allowing up to seven peripherals—such as hard drives and scanners—to be attached to the machine. Its floppy drive was increased to an 800 kB capacity. The Mac Plus was an immediate success and remained in production, unchanged, until October 15, 1990; on sale for just over four years and ten months, it was the longest-lived Macintosh in Apple's history until the 2nd generation Mac Pro that was introduced on December 19, 2013, surpassed this record on September 18, 2018. In September 1986 Apple introduced the Macintosh Programmer's Workshop, or MPW, an application that allowed software developers to create software for Macintosh on Macintosh, rather than cross compiling from a Lisa. In August 1987, Apple unveiled HyperCard and MultiFinder, which added cooperative multitasking to the operating system. Apple began bundling both with every Macintosh. Updated Motorola CPUs made a faster machine possible, and in 1987 Apple took advantage of the new Motorola technology and introduced the Macintosh II at $5500, powered by a Motorola 68020 processor. The primary improvement in the Macintosh II was Color QuickDraw in ROM, a color version of the graphics language which was the heart of the machine. Among the many innovations in Color QuickDraw were the ability to handle any display size, any color depth, and multiple monitors. The Macintosh II marked the start of a new direction for the Macintosh, as now for the first time it had an open architecture with several NuBus expansion slots, support for color graphics and external monitors, and a modular design similar to that of the IBM PC. It had an internal hard drive and a power supply with a fan, which was initially fairly loud. One third-party developer sold a device to regulate fan speed based on a heat sensor, but it voided the warranty. Later Macintosh computers had quieter power supplies and hard drives. The Macintosh SE was released at the same time as the Macintosh II for $2900 (or $3900 with hard drive), as the first compact Mac with a 20 MB internal hard drive and an expansion slot. The SE's expansion slot was located inside the case along with the CRT, potentially exposing an upgrader to high voltage. For this reason, Apple recommended users bring their SE to an authorized Apple dealer to have upgrades performed. The SE also updated Jerry Manock and Terry Oyama's original design and shared the Macintosh II's Snow White design language, as well as the new Apple Desktop Bus (ADB) mouse and keyboard that had first appeared on the Apple IIGS some months earlier. In 1987 Apple spun off its software business as Claris. It was given the code and rights to several applications, most notably MacWrite, MacPaint, and MacProject. In the late 1980s, Claris released a number of revamped software titles; the result was the "Pro" series, including MacDraw Pro, MacWrite Pro, and FileMaker Pro. To provide a complete office suite, Claris purchased the rights to the Informix Wingz spreadsheet program on the Mac, renaming it Claris Resolve, and added the new presentation software Claris Impact. By the early 1990s, Claris applications were shipping with the majority of consumer-level Macintoshes and were extremely popular. In 1991 Claris released ClarisWorks, which soon became their second best-selling application. When Claris was reincorporated back into Apple in 1998, ClarisWorks was renamed AppleWorks beginning with version 5.0. In 1988 Apple sued Microsoft and Hewlett-Packard on the grounds that they infringed Apple's copyrighted GUI, citing (among other things) the use of rectangular, overlapping, and resizable windows. After four years, the case was decided against Apple, as were later appeals. Apple's actions were criticized by some in the software community, including the Free Software Foundation (FSF), who felt Apple was trying to monopolize on GUIs in general, and boycotted GNU software for the Macintosh platform for seven years. With the new Motorola 68030 processor came the Macintosh IIx in 1988, which had benefited from internal improvements, including an on-board MMU. It was followed in 1989 by the Macintosh IIcx, a more compact version with fewer slots and a version of the Mac SE powered by the 68030, the Macintosh SE/30. Later that year, the Macintosh IIci, running at , was the first Mac to be "32-bit clean." This allowed it to natively support more than 8 MB of RAM, unlike its predecessors, which had "32-bit dirty" ROMs (8 of the 32 bits available for addressing were used for OS-level flags). System 7 was the first Macintosh operating system to support 32-bit addressing. The following year, the Macintosh IIfx, starting at US$9,900, was unveiled. Apart from its fast 68030 processor, it had significant internal architectural improvements, including faster memory and two Apple II CPUs (6502s) dedicated to input/output (I/O) processing. 1990–98: Decline and transition to PowerPC The third version of Microsoft Windows, Windows 3.0, was released in May 1990. Although still a graphical wrapper that relied upon MS-DOS, 3.0 was the first iteration of Windows which had a feature set and performance comparable to the much more expensive Macintosh platform. While the Macintosh was still mainly regarded as superior to Windows at the time, by this point, Windows "was good enough for the average user". It also did not help matters that during the previous year Jean-Louis Gassée had steadfastly refused to lower the profit margins on Mac computers. Finally, there was a component shortage that rocked the exponentially-expanding PC industry in 1989, forcing Apple USA head Allan Loren to cut prices, which dropped Apple's margins. In response, Apple introduced a range of relatively inexpensive Macs in October 1990. The Macintosh Classic, essentially a less expensive version of the Macintosh SE, was the least expensive Mac offered until early 2001. The 68020-powered Macintosh LC, in its distinctive "pizza box" case, offered color graphics and was accompanied by a new, low-cost 512×384 pixel monitor. The Macintosh IIsi was essentially a IIci with only one expansion slot. All three machines sold well, although Apple's profit margin on them was considerably lower than that on earlier models. Apple improved Macintosh computers by introducing models equipped with newly available processors from the 68k lineup. The Macintosh Classic II and Macintosh LC II, which used a 68030 CPU, were joined in 1991 by the Macintosh Quadra 700 and 900, the first Macs to employ the faster Motorola 68040 processor. Apple released their first portable computer, the Macintosh Portable in 1989. Although due to considerable design issues, it was soon replaced in 1991 with the first of the PowerBook line: the PowerBook 100, a miniaturized portable; the 68030 PowerBook 140; and the 68030 PowerBook 170. They were the first portable computers with the keyboard behind a palm rest and a built-in pointing device (a trackball) in front of the keyboard. The 1993 PowerBook 165c was Apple's first portable computer to feature a color screen, displaying 256 colors with -pixel resolution. The second generation of PowerBooks, the 68040-equipped 500 series, introduced trackpads, integrated stereo speakers, and built-in Ethernet to the laptop form factor in 1994. As for Mac OS, System 7 introduced a form of virtual memory, improved the performance of color graphics, and gained standard co-operative multitasking. Also during this time, the Macintosh began to shed the "Snow White" design language, along with the expensive consulting fees they were paying to Frog design. Apple instead brought the design work in-house by establishing the Apple Industrial Design Group, which took on responsibility for crafting a new look for all Apple products. Intel had tried unsuccessfully to push Apple to migrate the Macintosh platform to Intel chips. Apple concluded that Intel's complex instruction set computer (CISC) architecture ultimately would be unable to compete against reduced instruction set computer (RISC) processors. While the Motorola 68040 offered the same features as the Intel 80486 and could on a clock-for-clock basis significantly outperform the Intel chip, the 486 had the ability to be clocked significantly faster without suffering from overheating problems, especially the clock-doubled i486DX2 which ran the CPU logic at twice the external bus speed, giving such equipped IBM compatible systems a significant performance lead over their Macintosh equivalents. Apple's product design and engineering did not help matters as they restricted the use of the '040 to their expensive Quadras for a time while the 486 was readily available to OEMs as well as enthusiasts who put together their own machines. In late 1991, as the higher-end Macintosh desktop lineup transitioned to the '040, Apple was unable to offer the '040 in their top-of-the-line PowerBooks until early 1994 with the PowerBook 500 series, several years after the first 486-powered IBM compatible laptops hit the market which cost Apple considerable sales. In 1993 Intel rolled out the Pentium processors as the successor to the 486, while the Motorola 68050 was never released, leaving the Macintosh platform a generation behind IBM compatibles in the latest CPU technology. In 1994 Apple abandoned Motorola CPUs for the RISC PowerPC architecture developed by the AIM alliance of Apple Computer, IBM, and Motorola. The Power Macintosh line, the first to use the new chips, proved to be highly successful, with over a million PowerPC units sold in nine months. However, in the long run, spurning Intel for the PowerPC was a mistake as the commoditization of Intel-architecture chips meant Apple could not compete on price against "the Dells of the world". Notwithstanding these technical and commercial successes on the Macintosh, the falling costs of components made IBM PC compatibles cheaper and accelerated their adoption, over Macintosh systems that remained fairly expensive. A successful price war initiated by Compaq vaulted them from third place to first among PC manufacturers in 1994, overtaking a struggling IBM and relegating Apple to third place. Furthermore, Apple had created too many similar models that confused potential buyers. At one point, its product lineup was subdivided into Classic, LC, II, Quadra, Performa, and Centris models, with essentially the same computer being sold under a number of different names. These models competed against Macintosh clones, hardware manufactured by third parties to whom Apple had licensed System 7. This succeeded in increasing the Macintosh's market share somewhat and provided cheaper hardware for consumers, but hurt Apple financially as existing Apple customers began to buy cheaper clones which cannibalized the sales of Apple's higher-margin Macintosh systems, while Apple continued to bear the burden of developing Mac OS. Apple's market share further struggled due to the release of the Windows 95 operating system, which unified Microsoft's formerly separate MS-DOS and Windows products. Windows 95 significantly enhanced the multimedia ability and performance of IBM PC compatible computers and brought the abilities of Windows substantially nearer to parity with Mac OS. When Steve Jobs returned to Apple in 1997 following the company's purchase of NeXT, he ordered that the OS that had been previewed as System 7.7 be branded Mac OS 8, a name Apple had previously wished to preserve for the never-to-appear next generation Copland OS. This maneuver effectively ended the clone lines, as Apple had only licensed System 7 to clone manufacturers, not Mac OS 8. The decision caused significant financial losses for companies like Motorola, who produced the StarMax; Umax, who produced the SuperMac; and Power Computing, who offered several lines of Mac clones, including the PowerWave, PowerTower, and PowerTower Pro. These companies had invested substantial resources in creating their own Mac-compatible hardware. Apple bought out Power Computing's license but allowed Umax to continue selling Mac clones until their license expired, as they had a sizeable presence in the lower-end segment that Apple did not. In September 1997 Apple extended Umax's license allowing them to sell clones with Mac OS 8, the only clone maker to do so, but with the restriction that they only sell low-end systems. Without the higher profit margins of high-end systems, however, Umax judged this would not be profitable and exited the Mac clone market in May 1998, having lost US$36 million on the program. 1998–2005: Revival In 1998 Apple introduced its new iMac which, like the original 128K Mac, was an all-in-one computer. Its translucent plastic case, originally Bondi blue and later various additional colors, is considered an industrial design landmark of the late 1990s. The iMac did away with most of Apple's standard (and usually proprietary) connections, such as SCSI and ADB, in favor of two USB ports. It replaced a floppy disk drive with a CD-ROM drive for installing software, but could not write to CDs or other media without external third-party hardware. The iMac proved to be phenomenally successful, with 800,000 units sold in 139 days. It made the company an annual profit of US$309 million, Apple's first profitable year since Michael Spindler took over as CEO in 1995. This aesthetic was applied to the Power Macintosh G3 and later the iBook, Apple's first consumer-level notebook computer, filling the missing quadrant of Apple's "four-square product matrix" (desktop and portable products for both consumers and professionals). More than 140,000 pre-orders were placed before it began shipping in September, and by October proved to be a large success. The iMac also marked Apple's transition from the "Macintosh" name to the more simplistic "Mac". Apple completed the elimination of the Macintosh product name in 1999 when "Power Macintosh" was retired with the introduction of the Power Mac G4. In early 2001 Apple began shipping computers with CD-RW drives and emphasized the Mac's ability to play DVDs by including DVD-ROM and DVD-RAM drives as standard. Steve Jobs admitted that Apple had been "late to the party" on writable CD technology, but felt that Macs could become a "digital hub" that linked and enabled an "emerging digital lifestyle". Apple would later introduce an update to its iTunes music player software that enabled it to burn CDs, along with a controversial "Rip, Mix, Burn" advertising campaign that some felt encouraged media piracy. This accompanied the release of the iPod, Apple's first successful handheld device. Apple continued to launch products, such as the unsuccessful Power Mac G4 Cube, the education-oriented eMac, and the titanium (and later aluminum) PowerBook G4 notebook for professionals. The original iMac used a PowerPC G3 processor, but G4 and G5 chips were soon added, both accompanied by complete case redesigns that dropped the array of colors in favor of white plastic. As of 2007, all iMacs use aluminum cases. On January 11, 2005, Apple announced the Mac Mini, priced at US$499, making it the cheapest Mac. Mac OS continued to evolve up to version 9.2.2, including retrofits such as the addition of a nanokernel and support for Multiprocessing Services 2.0 in Mac OS 8.6, though its dated architecture made replacement necessary. From its beginnings on an 8 MHz machine with 128 KB of RAM, it had grown to support Apple's latest 1 GHz G4-equipped Macs. Since its architecture was first established, the lack of base features that were already common on Apple's competition, like preemptive multitasking and protected memory, reached a critical mass. As such, Apple introduced Mac OS X, a fully overhauled Unix-based successor to Mac OS 9. OS X uses Darwin, XNU, and Mach as foundations, and is based on NeXTSTEP. It was released to the public in September 2000 as the Mac OS X Public Beta, featuring a revamped user interface called "Aqua". At US$29.99, it allowed adventurous Mac users to sample Apple's new operating system and provide feedback for the actual release. The initial version of Mac OS X, 10.0 "Cheetah", was released on March 24, 2001. Older Mac OS applications could still run under early Mac OS X versions, using an environment called "Classic". Subsequent releases of Mac OS X included 10.1 "Puma" (2001), 10.2 "Jaguar" (2002), 10.3 "Panther" (2003) and 10.4 "Tiger" (2005). 2005–2011: Switch to Intel processors and unibody redesign Apple discontinued the use of PowerPC processors in 2006. At WWDC 2005, Steve Jobs announced this transition, revealing that Mac OS X was always developed to run on both the Intel and PowerPC architectures. This was done to make the company's computer more modern, keeping pace with Intel's low power Pentium M chips, especially for heat-sensitive laptops. The PowerPC G5 chip's heavy power consumption and heat output (the Power Mac G5 had to be liquid-cooled) also prevented its use in Mac notebook computers (as well as the original Mac mini), which were forced to use the older and slower PowerPC G4 chip. These shortcomings of the PowerPC chips were the main reasons behind the Mac's transition to Intel processors, and the brand was revitalized by the subsequent boost in processing power available due to greater efficiency and the ability to implement multiple cores in Mac CPUs. All Macs now used x86-64 processors made by Intel, and some were renamed as a result. Intel-based Macs running OS X 10.6 and below (support has been discontinued since 10.7) can run pre-existing software developed for PowerPC using an emulator named Rosetta, although at noticeably slower speeds than native programs. However, the Classic environment is now unavailable on the Intel architecture. Intel chips introduced the potential to run the Microsoft Windows operating system natively on Apple hardware, without emulation software such as Virtual PC. In March 2006 a group of hackers announced that they were able to run Windows XP on an Intel-based Mac. The group released their software as open source and has posted it for download on their website. On April 5, 2006, Apple announced the availability of the public beta of Boot Camp, software that allows owners of Intel-based Macs to install Windows XP on their machines; later versions added support for Windows Vista and Windows 7. Classic was discontinued in Mac OS X 10.5, and Boot Camp became a standard feature on Intel-based Macs. Starting in 2006, Apple's industrial design shifted to favor aluminum, which was used in the construction of the first MacBook Pro. Glass was added in 2008 with the introduction of the unibody MacBook Pro. These materials are billed as environmentally friendly. The iMac, MacBook Pro, MacBook Air, and Mac Mini lines currently all use aluminum enclosures, and are now made of a single unibody. Chief designer Sir Jonathan Ive guided products towards a minimalist and simple feel, including the elimination of replaceable batteries in notebooks. Multi-touch gestures from the iPhone's interface have been applied to the Mac line in the form of touch pads on notebooks and the Magic Mouse and Magic Trackpad for desktops. On February 24, 2011, Apple became the first company to bring to market a computer that used Intel's new Thunderbolt (codename Light Peak) I/O interface. Using the same physical interface as a Mini DisplayPort, and backwards compatible with that standard, Thunderbolt boasts two-way transfer speeds of 10 Gbit/s. 2011-2016: Post-Jobs era The iMac was redesigned in 2012 to feature significantly thinner side edges, faster processors, and the removal of the SuperDrive. At WWDC 2012, the new MacBook Pro with Retina display was announced, with a thinner body, faster CPUs and GPUs, a higher pixel density display similar to the iPhone's, MagSafe 2, and quieter impeller fans on the 15” model. It received mostly positive reviews, with Nilay Patel of The Verge calling it “one of the best displays to ever ship on a laptop”, although other reviewers criticized the lack of some ports and the removal of the SuperDrive. On WWDC 2013, the new Mac Pro was unveiled, with Phil Schiller saying “Can't innovate anymore, my ass!” in response to critics stating that Apple without Jobs could not innovate. It had an entirely new design, being much smaller, with a glossy dark gray cylindrical body, with a thermal core in the middle, with the components of the Mac built around it. It was released to generally positive reviews, although some criticized the lack of much upgradability. Apple released a service program in 2015 to let users of 2011 15” MacBook Pros get their logic board replaced, due to a fatal flaw where the AMD dedicated GPU becomes overheated and generates artifacts on the display, or refuses to function entirely. The MacBook was brought back in 2015 with a completely redesigned aluminum unibody chassis, with a 12” display, low power Intel Core M processors, a much more smaller logic board, tiered batteries to maximize use of the space, lack of any fans, a new Butterfly keyboard, a single USB-C port, and a solid-state Force Touch trackpad with pressure sensitivity. It was praised for its portability, but criticized for the lack of performance, and the need to use adapters to use most USB peripherals, and high starting price, the same as the 13” MacBook Pro's. In the same year, the MacBook Pro was updated to have more battery life, faster flash storage and the same Force Touch trackpad from the MacBook, being completely still in usage, with a Taptic Engine linear oscillator simulating the feel of a standard trackpad. 2016–2019: Critical reviews and lack of quality The 4th generation MacBook Pro was released at an Apple Special Event in October 2016, with a thinner design, the replacement of all ports except the headphone jack with USB-C ports, the Butterfly keyboard from the MacBook, P3 wide color gamut display, and the Touch Bar, an touchscreen OLED display strip replacing the function keys and the escape key on some models of the MacBook Pro, with a UI that changes and adapts depending on the application being used. It also replaces the power button with a Touch ID sensor on models with the Touch Bar. It was released to mixed reviews, with most reviewers criticizing the Touch Bar, which made it harder to use the function keys by feel, as it had no tactile feedback. The Verge's Miranda Nielsen described it as “I felt like a kid learning how to type again.”, with Dana Wollman from Engadget hitting the Touch Bar when she meant to hit the delete key. The USB-C ports were also a source of frustration for many users, especially the professional demographic of the MacBook Pro, requiring users to buy adapters or “dongles” to connect USB-A and SD card devices. A few months later many users reported the Butterfly keyboard on the MacBook and MacBook Pro getting stuck, or not registering letters. The problem was identified as dust or small foreign objects such as sand and food crumbs getting under the keyboard, jamming it and requiring customers to take it to an Apple Store or authorized service center to repair it. After years had gone by without the Mac Pro getting any meaningful updates, VP of marketing Phil Schiller admitted in 2017 that the current Mac Pro did not meet expectations and in an interview with tech reporters, said the following: “We know there are a number of customers who continue to buy our current Mac Pros. To be clear, our current Mac Pro has met the needs of some of our customers, and we know clearly not all of our customers. None of this is black and white, it’s a wide variety of customers. Some… it’s the kind of system they wanted; others, it was not.” “-As we’ve said, we made something bold that we thought would be great for the majority of our Mac Pro users. And what we discovered was that it was great for some and not others. Enough so that we need to take another path. One of the good things, hopefully, with Apple through the years has been a willingness to say when something isn’t quite what we wanted it to be, didn’t live up to expectations, to not be afraid to admit it and look for the next answer.” Craig Federighi, SVP of software engineering, also admitted in the same interview: “ I think we designed ourselves into a bit of a thermal corner, if you will. We designed a system with the kind of GPUs that at the time we thought we needed, and that we thought we could well serve with a two GPU architecture. That that was the thermal limit we needed, or the thermal capacity we needed. But workloads didn’t materialize to fit that as broadly as we hoped.” The iMac Pro was revealed at WWDC 2017 by John Ternus with Intel Xeon W processors and Radeon Vega graphics. It was partly a stopgap for professional users until the next generation Mac Pro arrived. In 2018, Apple refreshed the MacBook Pro with faster processors and a third-generation Butterfly keyboard, and the redesigned MacBook Air with a Retina display released in the same year added silicone gaskets to prevent dust and small objects from getting in, and launched a program to repair affected keyboards free of charge, but users continued to be affected by the issue. Some models of the 2018 MacBook Pro 15” had a flaw where the Core i9 processor would get uncomfortably hot, with YouTuber Dave Lee recording a maximum temperature of 93 degrees Celsius under load, and thermal throttled to the point it was slower than the 2017 15” MacBook Pro with a Core i7 CPU. Apple patched this issue by releasing a supplemental update to High Sierra, and stated: “Following extensive performance testing under numerous workloads, we’ve identified that there is a missing digital key in the firmware that impacts the thermal management system and could drive clock speeds down under heavy thermal loads on the new MacBook Pro. A bug fix is included in today’s macOS High Sierra 10.13.6 Supplemental Update and is recommended.” After installing the patch, Dave Lee noted that the MacBook Pro alleviated the issues, now not being nearly as hot. The MacBook Air was redesigned with a Retina display, Butterfly keyboard, Force Touch Trackpad, and removed all ports save for the headphone jack and replaced them with 2 Thunderbolt 3 USB-C ports. 2019–2020: Fixing flaws and focus on professionals The 2019 MacBook Pro and MacBook Air refreshes both removed the Butterfly keyboard and replaced them with what Apple dubbed the “Magic Keyboard”, which is largely identical to the scissor-switch mechanism used in MacBooks prior to 2016. The Touch Bar and Touch ID was also made standard on all MacBook Pros, with the Touch ID/power button now separated and moved more to the right, and the escape key now made physical and detached from the Touch Bar too. At WWDC 2019, then VP of hardware engineering John Ternus revealed the all-new Mac Pro, with a new design more akin to the Power Macs than the cylindrical design of the previous Mac Pro, with far more upgradability with Apple's own custom-designed PCIe expansion cards, the MPX modules, although standard PCIe devices such as AMD graphics cards work as well, although compatibility differs depending on the card. Almost every part is user-replaceable, with iFixit giving it a 9/10 repairability score. It gained positive reviews, with reviewers praising the modularity and upgradability, and quiet cooling, while also meeting the demands of professionals who were unsatisfied with the previous generation Mac Pro. 2020–present: Transition to Apple silicon In April 2018, Bloomberg published rumors stating that Apple intended to drop Intel chips and replace them with ARM processors similar to those used in its phones, causing Intel's shares to fall 6%. The Verge, commenting on the rumors, stated that such a decision made sense, as Intel was failing to make any significant improvements to its lineup and could not compete for battery life with ARM chips. At WWDC 2020, Tim Cook announced the transition to in-house SoCs, built upon an ARM architecture, over a two-year timeline. On November 10, 2020, Apple announced the first Macs to ship with Apple silicon: the MacBook Air, Mac Mini, and the 13" MacBook Pro. The MacBook Air was the only Mac to move exclusively to Apple silicon with this announcement, as the 13" MacBook Pro and the Mac Mini are still being sold with the option of an Intel processor. Paralleling the transition from PowerPC to Intel, Macs with Apple silicon can run software designed for Intel chips using an emulator called Rosetta 2. Apple allowed select developers to rent a Developer Transition Kit (DTK) for $500, with the agreement that they would return it after a year. The DTK was a Mac Mini with the iPad Pro's A12Z Bionic chip inside instead of a more traditional x86 Intel processor, to help developers optimize their apps for the upcoming Arm Macs. At an online November 2020 special event, Apple unveiled the first batch of ARM Macs, the MacBook Air, the 13” MacBook Pro, and the Mac Mini. They all had a custom-designed Apple M1 system on a chip (SoC), faster than any ARM processor ever produced by Apple, featuring 4 high-performance cores and 4 low-power cores, a 7-core GPU option in the MacBook Air or an 8-core GPU on more expensive models of the Air, and as standard on the Pro and Mini. Furthermore, they have a 16-core neural engine for up to 11 times faster machine-learning performance. As these chips are a lot less power-hungry, the MacBook Pro 13" has a battery life of up to 20 hours. It was released to immensely positive reviews, with most reviewers saying that it had longer battery life, was much cooler, and much faster than the Intel chips used in the previous generation. The Rosetta 2 translation software also worked with most Intel applications, with not much of a performance decrease, and much faster performance and adoption than Windows and Microsoft’s Surface Pro X. The iMac Pro was quietly discontinued in March 6, 2021 after only receiving 2 minor updates. On April 20, 2021, the new 24” iMac was revealed, coming in 7 new colors and the Apple M1 chip. The entire enclosure is now made from 100% recycled aluminum and is 11.5mm thin. The screen was upgraded from a 21.5” size to 24” 4.5K Retina display, with thinner white bezels. The new MacBook Pros were revealed on October 18, 2021, featuring a design similar to Apple’s Titanium PowerBook G4s and 2012 Retina MacBook Pros, bringing back the MagSafe, HDMI, and SD card ports, in addition to 3 Thunderbolt 4 USB-C ports and a high-impedance headphone jack. The displays now come in 14” and 16” configurations, featuring a mini-LED display with a 120Hz variable refresh rate screen. They sport either a M1 Pro or M1 Max chip, with up to 70% faster CPU performance than the M1, according to Apple. Current product line Hardware Apple contracts hardware production to Asian original equipment manufacturers such as Foxconn and Pegatron, maintaining a high degree of control over the end product. By contrast, most other companies (including Microsoft) create software that can be run on hardware produced by a variety of third parties such as Dell, HP Inc./Hewlett-Packard/Compaq, and Lenovo. Consequently, the Macintosh buyer has comparably fewer options but has superior integration compared to a Microsoft buyer. Most of the current Mac product family uses Intel x86-64 processors. The MacBook Air, some models of the MacBook Pro 13”, the iMac 24", and Mac Mini use Apple-designed M1 chips. Apple introduced an emulator during the transition from PowerPC chips (called Rosetta), much as it did during the transition from Motorola 68000 architecture a decade earlier. The Macintosh is the only mainstream computer platform to have successfully transitioned to a new CPU architecture, and has done so twice. All current Mac models ship with at least 8 GB of RAM as standard. Current Mac computers use AMD Radeon graphics cards as well as Intel graphics built into the main CPU. M1 Macs use an Apple-designed 7 or 8 core GPU. Previous Mac models have shipped with an optical media drive that includes a dual-function DVD/CD burner, referred to by Apple as a SuperDrive. However, Apple no longer ships any Macs with a built-in SuperDrive. Current Macs include two standard data transfer ports: USB and Thunderbolt (except for the Retina MacBook, which only has a USB-C port and headphone port). MacBook Pro, iMac, MacBook Air, and Mac Mini computers now also feature the "Thunderbolt" port, which Apple says can transfer data at speeds up to 10 gigabits per second. USB was introduced in the 1998 iMac G3 and is ubiquitous today, while FireWire was mainly reserved for high-performance devices such as hard drives or video cameras. Starting with the then-new iMac G5, released in October 2005, Apple began including built-in iSight cameras on appropriate models, and a media center interface called Front Row that can be operated by an Apple Remote or keyboard for accessing media stored on the computer. Front Row has been discontinued , however, and the Apple Remote is no longer bundled with new Macs. Apple was initially reluctant to embrace mice with multiple buttons and scroll wheels. Macs did not natively support pointing devices that featured multiple buttons, even from third parties, until Mac OS X arrived in 2001. Apple continued to offer only single button mice, in both wired and Bluetooth wireless versions, until August 2005, when it introduced the Mighty Mouse. While it looked like a traditional one-button mouse, it actually had four buttons and a scroll ball, capable of independent x- and y-axis movement. A Bluetooth version followed in July 2006. In October 2009, Apple introduced the Magic Mouse, which uses multi-touch gesture recognition (similar to that of the iPhone) instead of a physical scroll wheel or ball. It is available only in a wireless configuration, but the wired Mighty Mouse (re-branded as "Apple Mouse") was still available as an alternative until its discontinuation in 2017. Since 2010, Apple has also offered the Magic Trackpad as a means to control Macintosh desktop computers in a way similar to laptops. Software The original Macintosh was the first successful personal computer to use a graphical user interface devoid of a command line. It uses a desktop metaphor, depicting real-world objects like documents and a trash can as icons on-screen. Now known as the classic Mac OS, the System software was introduced in 1984 with the first Macintosh, renamed Mac OS in 1997, and continued to evolve until version 9.2.2. Originally, the hardware architecture was so closely tied to the classic Mac OS system that it was impossible to boot an alternative operating system. The most common workaround, is to boot into Mac OS and then to hand over control to a Mac OS-based bootloader application. Used even by Apple for A/UX and MkLinux, this technique is no longer necessary since the introduction of Open Firmware-based PCI Macs, though it was formerly used for convenience on many Old World ROM systems due to bugs in the firmware implementation. Since then, Mac hardware boots directly from Open Firmware in most PowerPC-based Macs or EFI in all Intel-based Macs. In 2001, Apple introduced Mac OS X (renamed OS X in 2012 and macOS in 2016), based on Darwin and NeXTSTEP; its new features included the Dock and the Aqua user interface. During the transition, Apple included a virtual machine subsystem known as Classic, allowing users to run Mac OS 9 applications under Mac OS X 10.4 and earlier on PowerPC machines. Because macOS is a Unix operating system that borrows heavily from FreeBSD, many applications written for Linux or BSD run on it, often using X11. There are many popular Macintosh software applications; many of those from large developers, such as Microsoft Office and Adobe Photoshop are actively developed for both macOS and Windows. A large amount of open-source software applications, such as the Firefox web browser and the LibreOffice office suite, are cross-platform, and thereby also run natively on macOS. Following the release of Intel-based Macs, third-party platform virtualization software such as Parallels Desktop, VMware Fusion, and VirtualBox began to emerge. These programs allow users to run Microsoft Windows or previously Windows-only software on Macs at near-native speed. Apple also released Boot Camp and Mac-specific Windows drivers that help users to install Windows XP, Vista, 7, 8, 8.1 or 10 and natively dual boot between Mac OS X and Windows. Although not condoned by Apple, it is possible to run the Linux operating system using Boot Camp or other virtualization workarounds. Unlike most PCs, however, Macs are unable to run many legacy PC operating systems. In particular, Intel-based Macs lack the A20 gate. Market share and user demographics 1984–97: Success and decline Since the introduction of the Macintosh, Apple has struggled to gain a significant share of the personal computer market. At first, the Macintosh 128K suffered from a dearth of available software compared to IBM's PC, resulting in disappointing sales in 1984 and 1985. It took 74 days for 50,000 units to sell. Although Apple was not able to overcome the tidal wave of IBM PCs and its clones, Macintosh systems found success in education and desktop publishing. Notwithstanding these technical and commercial successes on the Macintosh platform, their systems remained fairly expensive, making them less competitive in light of the falling costs of components that made IBM PC compatibles cheaper and accelerated their adoption. In 1989, Jean-Louis Gassée had steadfastly refused to lower the profit margins on Mac computers, then there was a component shortage that rocked the exponentially-expanding PC industry that year, forcing Apple USA head Allan Loren to cut prices which dropped Apple's margins. Microsoft Windows 3.0 was released in May 1990, the first iteration of Windows which had a feature set and performance comparable to the significantly costlier Macintosh. Furthermore, Apple had created too many similar models that confused potential buyers; at one point the product lineup was subdivided into Classic, LC, II, Quadra, Performa, and Centris models, with essentially the same computer being sold under a number of different names. Compaq, who had previously held the third-place spot among PC manufacturers during the 1980s and early/mid-1990s, initiated a successful price war in 1994 that vaulted them to the biggest by the year-end, overtaking a struggling IBM and relegating Apple to third place. Apple's market share further struggled due to the release of the Windows 95 operating system, which unified Microsoft's formerly separate MS-DOS and Windows products. Windows 95 significantly enhanced the multimedia capability and performance of IBM PC compatible computers, and brought the abilities of Windows to parity with the Mac OS GUI. 1997–2007: Comeback In 1997, upon return to Apple as interim CEO, Steve Jobs terminated the Macintosh clone program while simplifying the computer product lines. If measuring market share by installed base, there were more than 20 million Mac users by 1997, compared to an installed base of around 340 million Windows PCs. In 1998, the release of the iMac G3 all-in-one was a great success, selling 800,000 units in 139 days, providing a much needed boost to the ailing Macintosh platform. The introduction of the Power Macintosh G3 and iBook notebook completed "four-square product matrix" (desktop and portable products for both consumers and professionals), with the iBook ranking as the most popular laptop in the U.S. market for 1999. In 2000, Apple released the Power Mac G4 Cube, their first desktop since the discontinued Power Macintosh G3, to slot between the iMac G3 and the Power Mac G4. Even with its innovative design, it was initially priced US$200 higher than the comparably-equipped and more-expandable base Power Mac G4, while also not including a monitor, making it too expensive and resulting in slow sales. Apple sold just 29,000 Cubes in Q4 of 2000 which was one third of expectations, compared to 308,000 Macs during that same quarter, and Cube sales dropped to 12,000 units in Q1 of 2001. A price drop and hardware upgrades could not offset the earlier perception of the Cube's reduced value compared to the iMac and Power Mac G4 lineup, and it was discontinued in July 2001. Starting in 2002, Apple moved to eliminate CRT displays from its product line as part of aesthetic design and space-saving measures with the iMac G4. However, the new iMac with its flexible LCD flat-panel monitor was considerably more expensive on its debut than the preceding iMac G3, largely due to the higher cost of the LCD technology at the time. To keep the Macintosh affordable for the education market and due to the obsolescence of the iMac G3, Apple created the eMac in April 2002 as the intended successor. However, the eMac's CRT made it relatively bulky and somewhat outdated, while its all-in-one construction meant it could not be expanded to meet consumer demand for larger monitors. The iMac G4's relatively high prices were approaching that of laptops which were portable and had higher resolution LCD screens. Meanwhile, Windows PC manufacturers could offer desktop configurations with LCD flat-panel monitors at prices comparable to the eMac and at a much lower cost than the iMac G4. The flop of the Power Mac G4 Cube, along with the more expensive iMac G4 and heavy eMac, meant that Macintosh desktop sales never reached the market share attained by the previous iMac G3. For the next half-decade while Macintosh sales held steady, it would instead be the iPod portable music player and iTunes music download service that would drive Apple's sales growth. Statistics from late 2003 indicate that Apple had 2.06 percent of the desktop share in the United States that had increased to 2.88 percent by Q4 2004. As of October 2006, research firms IDC and Gartner reported that Apple's market share in the U.S. had increased to about 6 percent. Figures from December 2006, showing a market share around 6 percent (IDC) and 6.1 percent (Gartner) are based on a more than 30 percent increase in unit sale from 2005 to 2006. The installed base of Mac computers is hard to determine, with numbers ranging from 5% (estimated in 2009) to 16% (estimated in 2005). 2007–present: "Post-PC" era In recent years, market share of the personal computer market is measured by browser hits, sales and installed base. If using the browser metric, Mac market share increased substantially in 2007. Mac OS X's share of the OS market increased from 7.31% in December 2007 to 9.63% in December 2008, which is a 32% increase in market share during 2008, compared with a 22% increase during 2007. From 2001 to 2008, Mac sales increased continuously on an annual basis. Apple reported worldwide sales of 3.36 million Macs during the 2009 holiday season. As of Mid-2011, the Macintosh continues to enjoy rapid market share increase in the US, growing from 7.3% of all computer shipments in 2010 to 9.3% in 2011. According to IDC's quarterly PC tracker, globally, in 3rd quarter of 2014, Apple's PC market share increased 5.7 percent year over year, with record sales of 5.5 million units. Apple now sits in the number five spot, with a global market share of about 6% during 2014, behind Lenovo, HP, Dell and Acer. By March 2011, the market share of OS X in North America had increased to slightly over 14%. Whether the size of the Mac's market share and installed base is relevant, and to whom, is a hotly debated issue. Industry pundits have often called attention to the Mac's relatively small market share to predict Apple's impending doom, particularly in the early and mid-1990s when the company's future seemed bleakest. Others argue that market share is the wrong way to judge the Mac's success. Apple has positioned the Mac as a higher-end personal computer, and so it may be misleading to compare it to a budget PC. Because the overall market for personal computers has grown rapidly, the Mac's increasing sales numbers are effectively swamped by the industry's expanding sales volume as a whole. Apple's small market share, then, gives the impression that fewer people are using Macs than did ten years ago, when exactly the opposite is true. Soaring sales of the iPhone and iPad mean that the portion of Apple's profits represented by the Macintosh has declined in 2010, dropping to 24% from 46% two years earlier. Others try to de-emphasize market share, citing that it is rarely brought up in other industries. Regardless of the Mac's market share, Apple has remained profitable since Steve Jobs's return and the company's subsequent reorganization. Notably, a report published in the first quarter of 2008 found that Apple had a 14% market share in the personal computer market in the US, with 66% of all computers over $1,000. Market research indicates that Apple draws its customer base from a higher-income demographic than the mainstream personal computer market. The sales breakdown of the Macintosh have seen sales of desktop Macs stayed mostly constant while being surpassed by that of Mac notebooks whose sales rate has grown considerably; seven out of ten Macs sold were notebooks in 2009, a ratio projected to rise to three out of four by 2010. The change in sales of form factors is due to the desktop iMac moving from affordable (iMac G3) to upscale (iMac G4) and subsequent releases are considered premium all-in-ones. By contrast, the MSRP of the MacBook notebook lines have dropped through successive generations such that the MacBook Air and MacBook Pro constitute the lowest price of entry to a Mac, with the exception of the even more inexpensive Mac Mini (the only sub-$1000 offering from Apple, albeit without a monitor and keyboard), not surprisingly the MacBooks are the top-selling form factors of the Macintosh platform today. The use of Intel microprocessors has helped Macs more directly compete with their Windows counterparts on price and performance, and by the 2010s Apple was receiving Intel's latest CPUs first before other PC manufacturers. In recent years, Apple has seen a significant boost in sales of Macs. This has been attributed, in part, to the success of the iPod and the iPhone, a halo effect whereby satisfied iPod or iPhone owners purchase more Apple products, and Apple has since capitalized on that with the iCloud cloud service that allows users to seamlessly sync data between these devices and Macs. Nonetheless, like other personal computer manufacturers, the Macintosh lines have been hurt by consumer trend towards smartphones and tablet computers (particularly Apple's own iPhone and iPad, respectively) as the computing devices of choice among consumers. Although the PC market declined, Apple still managed to ship 2.8 million MacBooks in Q2 2012 (the majority of which are the MacBook Air) compared to 500,000 total Ultrabooks, although there were dozens of Ultrabooks from various manufacturers on the market while Apple only offered 11-inch and 13-inch models of the MacBook Air. The Air has been the best-selling ultra-portable in certain countries over Windows Ultrabooks, particularly the United States. While several Ultrabooks were able to claim individual distinctions such as being the lightest or thinnest, the Air was regarded by reviewers as the best all-around subnotebook/ultraportable in regard to "OS X experience, full keyboard, superior trackpad, Thunderbolt connector and the higher-quality, all-aluminum unibody construction". The Air was among the first to receive Intel's latest CPUs before other PC manufacturers, and OS X has gained market share on Windows in recent years. Through July 1, 2013, the MacBook Air took in 56 percent of all Ultrabook sales in the United States, although being one of the higher-priced competitors, though several Ultrabooks with better features were often more expensive than the MacBook Air. The competitive pricing of MacBooks was particularly effective when rivals charged more for seemingly equivalent Ultrabooks, as this contradicted the established "elitist aura" perception that Apple products cost more but were higher quality, which made these most expensive Ultrabooks seem exorbitant no matter how valid their higher prices were. Apple has generally dominated the premium PC market, having a 91 percent market share for PCs priced at more than $1,000 in 2009, according to NPD. The Macintosh took 45 percent of operating profits in the PC industry during Q4 2012, compared to 13 percent for Dell, seven percent for Hewlett Packard, six percent for Lenovo and Asus, and one percent for Acer. While sales of the Macintosh have largely held steady, in comparison to Apple's sales of the iPhone and iPad which increased significantly during the 2010s, Macintosh computers still enjoy high margins on a per unit basis, with the majority being their MacBooks that are focused on the ultraportable niche that is the most profitable and only growing segment of PCs. It also helped that the Macintosh lineup is simple, updated on a yearly schedule, and consistent across both Apple retail stores, and authorized resellers where they have a special "store within a store" section to distinguish them from Windows PCs. In contrast, Windows PC manufacturers generally have a wide range of offerings, selling only a portion through retail with a full selection on the web, and often with limited-time or region-specific models. The Macintosh ranked third on the "list of intended brands for desktop purchases" for the 2011 holiday season, then moved up to second in 2012 by displacing Hewlett Packard, and in 2013 took the top spot ahead of Dell. See also References Further reading This is an interview about the introduction of the Macintosh. External links Macintosh computers Computer-related introductions in 1984 68000-based home computers Macintosh platform Apple computers Sealed computers Steve Jobs

Operating System (OS)

BIOS In computing, BIOS (, ; Basic Input/Output System, also known as the System BIOS, ROM BIOS, BIOS ROM or PC BIOS) is firmware used to provide runtime services for operating systems and programs and to perform hardware initialization during the booting process (power-on startup). The BIOS firmware comes pre-installed on an IBM PC or IBM PC compatible's system board and exists in UEFI-based systems too. The name originates from the Basic Input/Output System used in the CP/M operating system in 1975. The BIOS originally proprietary to the IBM PC has been reverse engineered by some companies (such as Phoenix Technologies) looking to create compatible systems. The interface of that original system serves as a de facto standard. The BIOS in modern PCs initializes and tests the system hardware components (Power-on self-test), and loads a boot loader from a mass storage device which then initializes an operating system. In the era of DOS, the BIOS provided BIOS interrupt calls for the keyboard, display, storage, and other input/output (I/O) devices that standardized an interface to application programs and the operating system. More recent operating systems do not use the BIOS interrupt calls after startup. Most BIOS implementations are specifically designed to work with a particular computer or motherboard model, by interfacing with various devices especially system chipset. Originally, BIOS firmware was stored in a ROM chip on the PC motherboard. In later computer systems, the BIOS contents are stored on flash memory so it can be rewritten without removing the chip from the motherboard. This allows easy, end-user updates to the BIOS firmware so new features can be added or bugs can be fixed, but it also creates a possibility for the computer to become infected with BIOS rootkits. Furthermore, a BIOS upgrade that fails could brick the motherboard. The last version of Microsoft Windows running on PCs which uses BIOS firmware is Windows 10. Unified Extensible Firmware Interface (UEFI) is a successor to the legacy PC BIOS, aiming to address its technical limitations. History The term BIOS (Basic Input/Output System) was created by Gary Kildall and first appeared in the CP/M operating system in 1975, describing the machine-specific part of CP/M loaded during boot time that interfaces directly with the hardware. (A CP/M machine usually has only a simple boot loader in its ROM.) Versions of MS-DOS, PC DOS or DR-DOS contain a file called variously "IO.SYS", "IBMBIO.COM", "IBMBIO.SYS", or "DRBIOS.SYS"; this file is known as the "DOS BIOS" (also known as the "DOS I/O System") and contains the lower-level hardware-specific part of the operating system. Together with the underlying hardware-specific but operating system-independent "System BIOS", which resides in ROM, it represents the analogue to the "CP/M BIOS". The BIOS originally proprietary to the IBM PC has been reverse engineered by some companies (such as Phoenix Technologies) looking to create compatible systems. With the introduction of PS/2 machines, IBM divided the System BIOS into real- and protected-mode portions. The real-mode portion was meant to provide backward compatibility with existing operating systems such as DOS, and therefore was named "CBIOS" (for "Compatibility BIOS"), whereas the "ABIOS" (for "Advanced BIOS") provided new interfaces specifically suited for multitasking operating systems such as OS/2. User interface The BIOS of the original IBM PC and XT had no interactive user interface. Error codes or messages were displayed on the screen, or coded series of sounds were generated to signal errors when the power-on self-test (POST) had not proceeded to the point of successfully initializing a video display adapter. Options on the IBM PC and XT were set by switches and jumpers on the main board and on expansion cards. Starting around the mid-1990s, it became typical for the BIOS ROM to include a "BIOS configuration utility" (BCU) or "BIOS setup utility", accessed at system power-up by a particular key sequence. This program allowed the user to set system configuration options, of the type formerly set using DIP switches, through an interactive menu system controlled through the keyboard. In the interim period, IBM-compatible PCsincluding the IBM ATheld configuration settings in battery-backed RAM and used a bootable configuration program on floppy disk, not in the ROM, to set the configuration options contained in this memory. The floppy disk was supplied with the computer, and if it was lost the system settings could not be changed. The same applied in general to computers with an EISA bus, for which the configuration program was called an EISA Configuration Utility (ECU). A modern Wintel-compatible computer provides a setup routine essentially unchanged in nature from the ROM-resident BIOS setup utilities of the late 1990s; the user can configure hardware options using the keyboard and video display. The modern Wintel machine may store the BIOS configuration settings in flash ROM, perhaps the same flash ROM that holds the BIOS itself. Operation System startup Early Intel processors started at physical address 000FFFF0h. Systems with later processors provide logic to start running the BIOS from the system ROM. If the system has just been powered up or the reset button was pressed ("cold boot"), the full power-on self-test (POST) is run. If Ctrl+Alt+Delete was pressed ("warm boot"), a special flag value stored in nonvolatile BIOS memory ("CMOS") tested by the BIOS allows bypass of the lengthy POST and memory detection. The POST identifies, tests and initializes system devices such as the CPU, chipset, RAM, motherboard, video card, keyboard, mouse, hard disk drive, optical disc drive and other hardware, including integrated peripherals. Early IBM PCs had a routine in the POST that would download a program into RAM through the keyboard port and run it. This feature was intended for factory test or diagnostic purposes. Boot process After the option ROM scan is completed and all detected ROM modules with valid checksums have been called, or immediately after POST in a BIOS version that does not scan for option ROMs, the BIOS calls INT 19h to start boot processing. Post-boot, programs loaded can also call INT 19h to reboot the system, but they must be careful to disable interrupts and other asynchronous hardware processes that may interfere with the BIOS rebooting process, or else the system may hang or crash while it is rebooting. When INT 19h is called, the BIOS attempts to locate boot loader software on a "boot device", such as a hard disk, a floppy disk, CD, or DVD. It loads and executes the first boot software it finds, giving it control of the PC. The BIOS uses the boot devices set in Nonvolatile BIOS memory (CMOS), or, in the earliest PCs, DIP switches. The BIOS checks each device in order to see if it is bootable by attempting to load the first sector (boot sector). If the sector cannot be read, the BIOS proceeds to the next device. If the sector is read successfully, some BIOSes will also check for the boot sector signature 0x55 0xAA in the last two bytes of the sector (which is 512 bytes long), before accepting a boot sector and considering the device bootable. When a bootable device is found, the BIOS transfers control to the loaded sector. The BIOS does not interpret the contents of the boot sector other than to possibly check for the boot sector signature in the last two bytes. Interpretation of data structures like partition tables and BIOS Parameter Blocks is done by the boot program in the boot sector itself or by other programs loaded through the boot process. A non-disk device such as a network adapter attempts booting by a procedure that is defined by its option ROM or the equivalent integrated into the motherboard BIOS ROM. As such, option ROMs may also influence or supplant the boot process defined by the motherboard BIOS ROM. With the El Torito optical media boot standard, the optical drive actually emulates a 3.5" high-density floppy disk to the BIOS for boot purposes. Reading the "first sector" of a CD-ROM or DVD-ROM is not a simply defined operation like it is on a floppy disk or a hard disk. Furthermore, the complexity of the medium makes it difficult to write a useful boot program in one sector. The bootable virtual floppy disk can contain software that provides access to the optical medium in its native format. Boot priority The user can select the boot priority implemented by the BIOS. For example, most computers have a hard disk that is bootable, but sometimes there is a removable-media drive that has higher boot priority, so the user can cause a removable disk to be booted. In most modern BIOSes, the boot priority order can be configured by the user. In older BIOSes, limited boot priority options are selectable; in the earliest BIOSes, a fixed priority scheme was implemented, with floppy disk drives first, fixed disks (i.e. hard disks) second, and typically no other boot devices supported, subject to modification of these rules by installed option ROMs. The BIOS in an early PC also usually would only boot from the first floppy disk drive or the first hard disk drive, even if there were two drives installed. Boot failure On the original IBM PC and XT, if no bootable disk was found, ROM BASIC was started by calling INT 18h. Since few programs used BASIC in ROM, clone PC makers left it out; then a computer that failed to boot from a disk would display "No ROM BASIC" and halt (in response to INT 18h). Later computers would display a message like "No bootable disk found"; some would prompt for a disk to be inserted and a key to be pressed to retry the boot process. A modern BIOS may display nothing or may automatically enter the BIOS configuration utility when the boot process fails. Boot environment The environment for the boot program is very simple: the CPU is in real mode and the general-purpose and segment registers are undefined, except SS, SP, CS, and DL. CS:IP always points to physical address 0x07C00. What values CS and IP actually have is not well defined. Some BIOSes use a CS:IP of 0x0000:0x7C00 while others may use 0x07C0:0x0000. Because boot programs are always loaded at this fixed address, there is no need for a boot program to be relocatable. DL may contain the drive number, as used with INT 13h, of the boot device. SS:SP points to a valid stack that is presumably large enough to support hardware interrupts, but otherwise SS and SP are undefined. (A stack must be already set up in order for interrupts to be serviced, and interrupts must be enabled in order for the system timer-tick interrupt, which BIOS always uses at least to maintain the time-of-day count and which it initializes during POST, to be active and for the keyboard to work. The keyboard works even if the BIOS keyboard service is not called; keystrokes are received and placed in the 15-character type-ahead buffer maintained by BIOS.) The boot program must set up its own stack, because the size of the stack set up by BIOS is unknown and its location is likewise variable; although the boot program can investigate the default stack by examining SS:SP, it is easier and shorter to just unconditionally set up a new stack. At boot time, all BIOS services are available, and the memory below address 0x00400 contains the interrupt vector table. BIOS POST has initialized the system timers, interrupt controller(s), DMA controller(s), and other motherboard/chipset hardware as necessary to bring all BIOS services to ready status. DRAM refresh for all system DRAM in conventional memory and extended memory, but not necessarily expanded memory, has been set up and is running. The interrupt vectors corresponding to the BIOS interrupts have been set to point at the appropriate entry points in the BIOS, hardware interrupt vectors for devices initialized by the BIOS have been set to point to the BIOS-provided ISRs, and some other interrupts, including ones that BIOS generates for programs to hook, have been set to a default dummy ISR that immediately returns. The BIOS maintains a reserved block of system RAM at addresses 0x00400–0x004FF with various parameters initialized during the POST. All memory at and above address 0x00500 can be used by the boot program; it may even overwrite itself. Extensions (option ROMs) Peripheral cards such as hard disk drive host bus adapters and video cards have their own firmware, and BIOS extension option ROM may be a part of the expansion card firmware, which provide additional functionality to BIOS. Code in option ROMs runs before the BIOS boots the operating system from mass storage. These ROMs typically test and initialize hardware, add new BIOS services, or replace existing BIOS services with their own services. For example, a SCSI controller usually has a BIOS extension ROM that adds support for hard drives connected through that controller. An extension ROM could in principle contain operating system, or it could implement an entirely different boot process such as network booting. Operation of an IBM-compatible computer system can be completely changed by removing or inserting an adapter card (or a ROM chip) that contains a BIOS extension ROM. The motherboard BIOS typically contains code for initializing and bootstrapping integrated display and integrated storage. In addition, plug-in adapter cards such as SCSI, RAID, network interface cards, and video cards often include their own BIOS (e.g. Video BIOS), complementing or replacing the system BIOS code for the given component. Even devices built into the motherboard can behave in this way; their option ROMs can be a part of the motherboard BIOS. An add-in card requires an option ROM if the card is not supported by the motherboard BIOS and the card needs to be initialized or made accessible through BIOS services before the operating system can be loaded (usually this means it is required in the boot process). An additional advantage of ROM on some early PC systems (notably including the IBM PCjr) was that ROM was faster than main system RAM. (On modern systems, the case is very much the reverse of this, and BIOS ROM code is usually copied ("shadowed") into RAM so it will run faster.) Boot procedure If an expansion ROM wishes to change the way the system boots (such as from a network device or a SCSI adapter) in a cooperative way, it can use the BIOS Boot Specification (BBS) API to register its ability to do so. Once the expansion ROMs have registered using the BBS APIs, the user can select among the available boot options from within the BIOS's user interface. This is why most BBS compliant PC BIOS implementations will not allow the user to enter the BIOS's user interface until the expansion ROMs have finished executing and registering themselves with the BBS API. Also, if an expansion ROM wishes to change the way the system boots unilaterally, it can simply hook INT 19h or other interrupts normally called from interrupt 19h, such as INT 13h, the BIOS disk service, to intercept the BIOS boot process. Then it can replace the BIOS boot process with one of its own, or it can merely modify the boot sequence by inserting its own boot actions into it, by preventing the BIOS from detecting certain devices as bootable, or both. Before the BIOS Boot Specification was promulgated, this was the only way for expansion ROMs to implement boot capability for devices not supported for booting by the native BIOS of the motherboard. Initialization After the motherboard BIOS completes its POST, most BIOS versions search for option ROM modules, also called BIOS extension ROMs, and execute them. The motherboard BIOS scans for extension ROMs in a portion of the "upper memory area" (the part of the x86 real-mode address space at and above address 0xA0000) and runs each ROM found, in order. To discover memory-mapped option ROMs, a BIOS implementation scans the real-mode address space from 0x0C0000 to 0x0F0000 on 2 KB (2,048 bytes) boundaries, looking for a two-byte ROM signature: 0x55 followed by 0xAA. In a valid expansion ROM, this signature is followed by a single byte indicating the number of 512-byte blocks the expansion ROM occupies in real memory, and the next byte is the option ROM's entry point (also known as its "entry offset"). If the ROM has a valid checksum, the BIOS transfers control to the entry address, which in a normal BIOS extension ROM should be the beginning of the extension's initialization routine. At this point, the extension ROM code takes over, typically testing and initializing the hardware it controls and registering interrupt vectors for use by post-boot applications. It may use BIOS services (including those provided by previously initialized option ROMs) to provide a user configuration interface, to display diagnostic information, or to do anything else that it requires. It is possible that an option ROM will not return to BIOS, pre-empting the BIOS's boot sequence altogether. An option ROM should normally return to the BIOS after completing its initialization process. Once (and if) an option ROM returns, the BIOS continues searching for more option ROMs, calling each as it is found, until the entire option ROM area in the memory space has been scanned. Physical placement Option ROMs normally reside on adapter cards. However, the original PC, and perhaps also the PC XT, have a spare ROM socket on the motherboard (the "system board" in IBM's terms) into which an option ROM can be inserted, and the four ROMs that contain the BASIC interpreter can also be removed and replaced with custom ROMs which can be option ROMs. The IBM PCjr is unique among PCs in having two ROM cartridge slots on the front. Cartridges in these slots map into the same region of the upper memory area used for option ROMs, and the cartridges can contain option ROM modules that the BIOS would recognize. The cartridges can also contain other types of ROM modules, such as BASIC programs, that are handled differently. One PCjr cartridge can contain several ROM modules of different types, possibly stored together in one ROM chip. Operating system services The BIOS ROM is customized to the particular manufacturer's hardware, allowing low-level services (such as reading a keystroke or writing a sector of data to diskette) to be provided in a standardized way to programs, including operating systems. For example, an IBM PC might have either a monochrome or a color display adapter (using different display memory addresses and hardware), but a single, standard, BIOS system call may be invoked to display a character at a specified position on the screen in text mode or graphics mode. The BIOS provides a small library of basic input/output functions to operate peripherals (such as the keyboard, rudimentary text and graphics display functions and so forth). When using MS-DOS, BIOS services could be accessed by an application program (or by MS-DOS) by executing an INT 13h interrupt instruction to access disk functions, or by executing one of a number of other documented BIOS interrupt calls to access video display, keyboard, cassette, and other device functions. Operating systems and executive software that are designed to supersede this basic firmware functionality provide replacement software interfaces to application software. Applications can also provide these services to themselves. This began even in the 1980s under MS-DOS, when programmers observed that using the BIOS video services for graphics display were very slow. To increase the speed of screen output, many programs bypassed the BIOS and programmed the video display hardware directly. Other graphics programmers, particularly but not exclusively in the demoscene, observed that there were technical capabilities of the PC display adapters that were not supported by the IBM BIOS and could not be taken advantage of without circumventing it. Since the AT-compatible BIOS ran in Intel real mode, operating systems that ran in protected mode on 286 and later processors required hardware device drivers compatible with protected mode operation to replace BIOS services. In modern PCs running modern operating systems (such as Windows and Linux) the BIOS interrupt calls is used only during booting and initial loading of operating systems. Before the operating system's first graphical screen is displayed, input and output are typically handled through BIOS. A boot menu such as the textual menu of Windows, which allows users to choose an operating system to boot, to boot into the safe mode, or to use the last known good configuration, is displayed through BIOS and receives keyboard input through BIOS. Many modern PCs can still boot and run legacy operating systems such as MS-DOS or DR-DOS that rely heavily on BIOS for their console and disk I/O, providing that the system has a BIOS, or a CSM-capable UEFI firmware. Processor microcode updates Intel processors have reprogrammable microcode since the P6 microarchitecture. AMD processors have reprogrammable microcode since the K7 microarchitecture. The BIOS contain patches to the processor microcode that fix errors in the initial processor microcode; microcode is loaded into processor's SRAM so reprogramming is not persistent, thus loading of microcode updates is performed each time the system is powered up. Without reprogrammable microcode, an expensive processor swap would be required; for example, the Pentium FDIV bug became an expensive fiasco for Intel as it required a product recall because the original Pentium processor's defective microcode could not be reprogrammed. Operating systems can update main processor microcode also. Identification Some BIOSes contain a software licensing description table (SLIC), a digital signature placed inside the BIOS by the original equipment manufacturer (OEM), for example Dell. The SLIC is inserted into the ACPI data table and contains no active code. Computer manufacturers that distribute OEM versions of Microsoft Windows and Microsoft application software can use the SLIC to authenticate licensing to the OEM Windows Installation disk and system recovery disc containing Windows software. Systems with a SLIC can be preactivated with an OEM product key, and they verify an XML formatted OEM certificate against the SLIC in the BIOS as a means of self-activating (see System Locked Preinstallation, SLP). If a user performs a fresh install of Windows, they will need to have possession of both the OEM key (either SLP or COA) and the digital certificate for their SLIC in order to bypass activation. This can be achieved if the user performs a restore using a pre-customised image provided by the OEM. Power users can copy the necessary certificate files from the OEM image, decode the SLP product key, then perform SLP activation manually. Cracks for non-genuine Windows distributions usually edit the SLIC or emulate it in order to bypass Windows activation. Overclocking Some BIOS implementations allow overclocking, an action in which the CPU is adjusted to a higher clock rate than its manufacturer rating for guaranteed capability. Overclocking may, however, seriously compromise system reliability in insufficiently cooled computers and generally shorten component lifespan. Overclocking, when incorrectly performed, may also cause components to overheat so quickly that they mechanically destroy themselves. Modern use Some older operating systems, for example MS-DOS, rely on the BIOS to carry out most input/output tasks within the PC. Calling real mode BIOS services directly is inefficient for protected mode (and long mode) operating systems. BIOS interrupt calls are not used by modern multitasking operating systems after they initially load. In 1990s, BIOS provided some protected mode interfaces for Microsoft Windows and Unix-like operating systems, such as Advanced Power Management (APM), Plug and Play BIOS, Desktop Management Interface (DMI), VESA BIOS Extensions (VBE), e820 and MultiProcessor Specification (MPS). Starting from the 2000, most BIOSes provide ACPI, SMBIOS, VBE and e820 interfaces for modern operating systems. After operating systems load, the System Management Mode code is still running in SMRAM. Since 2010, BIOS technology is in a transitional process toward UEFI. Configuration Setup utility Historically, the BIOS in the IBM PC and XT had no built-in user interface. The BIOS versions in earlier PCs (XT-class) were not software configurable; instead, users set the options via DIP switches on the motherboard. Later computers, including all IBM-compatibles with 80286 CPUs, had a battery-backed nonvolatile BIOS memory (CMOS RAM chip) that held BIOS settings. These settings, such as video-adapter type, memory size, and hard-disk parameters, could only be configured by running a configuration program from a disk, not built into the ROM. A special "reference diskette" was inserted in an IBM AT to configure settings such as memory size. Early BIOS versions did not have passwords or boot-device selection options. The BIOS was hard-coded to boot from the first floppy drive, or, if that failed, the first hard disk. Access control in early AT-class machines was by a physical keylock switch (which was not hard to defeat if the computer case could be opened). Anyone who could switch on the computer could boot it. Later, 386-class computers started integrating the BIOS setup utility in the ROM itself, alongside the BIOS code; these computers usually boot into the BIOS setup utility if a certain key or key combination is pressed, otherwise the BIOS POST and boot process are executed. A modern BIOS setup utility has a text user interface (TUI) or graphical user interface (GUI) accessed by pressing a certain key on the keyboard when the PC starts. Usually, the key is advertised for short time during the early startup, for example "Press DEL to enter Setup". The actual key depends on specific hardware. Features present in the BIOS setup utility typically include: Configuring, enabling and disabling the hardware components Setting the system time Setting the boot order Setting various passwords, such as a password for securing access to the BIOS user interface and preventing malicious users from booting the system from unauthorized portable storage devices, or a password for booting the system Hardware monitoring A modern BIOS setup screen often features a PC Health Status or a Hardware Monitoring tab, which directly interfaces with a Hardware Monitor chip of the mainboard. This makes it possible to monitor CPU and chassis temperature, the voltage provided by the power supply unit, as well as monitor and control the speed of the fans connected to the motherboard. Once the system is booted, hardware monitoring and computer fan control is normally done directly by the Hardware Monitor chip itself, which can be a separate chip, interfaced through I2C or SMBus, or come as a part of a Super I/O solution, interfaced through Industry Standard Architecture (ISA) or Low Pin Count (LPC). Some operating systems, like NetBSD with envsys and OpenBSD with sysctl hw.sensors, feature integrated interfacing with hardware monitors. However, in some circumstances, the BIOS also provides the underlying information about hardware monitoring through ACPI, in which case, the operating system may be using ACPI to perform hardware monitoring. Reprogramming In modern PCs the BIOS is stored in rewritable EEPROM or NOR flash memory, allowing the contents to be replaced and modified. This rewriting of the contents is sometimes termed flashing. It can be done by a special program, usually provided by the system's manufacturer, or at POST, with a BIOS image in a hard drive or USB flash drive. A file containing such contents is sometimes termed "a BIOS image". A BIOS might be reflashed in order to upgrade to a newer version to fix bugs or provide improved performance or to support newer hardware. Hardware The original IBM PC BIOS (and cassette BASIC) was stored on mask-programmed read-only memory (ROM) chips in sockets on the motherboard. ROMs could be replaced, but not altered, by users. To allow for updates, many compatible computers used re-programmable BIOS memory devices such as EPROM, EEPROM and later flash memory (usually NOR flash) devices. According to Robert Braver, the president of the BIOS manufacturer Micro Firmware, Flash BIOS chips became common around 1995 because the electrically erasable PROM (EEPROM) chips are cheaper and easier to program than standard ultraviolet erasable PROM (EPROM) chips. Flash chips are programmed (and re-programmed) in-circuit, while EPROM chips need to be removed from the motherboard for re-programming. BIOS versions are upgraded to take advantage of newer versions of hardware and to correct bugs in previous revisions of BIOSes. Beginning with the IBM AT, PCs supported a hardware clock settable through BIOS. It had a century bit which allowed for manually changing the century when the year 2000 happened. Most BIOS revisions created in 1995 and nearly all BIOS revisions in 1997 supported the year 2000 by setting the century bit automatically when the clock rolled past midnight, 31 December 1999. The first flash chips were attached to the ISA bus. Starting in 1998, the BIOS flash moved to the LPC bus, following a new standard implementation known as "firmware hub" (FWH). In 2006, the BIOS flash memory moved to the SPI bus. The size of the BIOS, and the capacity of the ROM, EEPROM, or other media it may be stored on, has increased over time as new features have been added to the code; BIOS versions now exist with sizes up to 32 megabytes. For contrast, the original IBM PC BIOS was contained in an 8 KB mask ROM. Some modern motherboards are including even bigger NAND flash memory ICs on board which are capable of storing whole compact operating systems, such as some Linux distributions. For example, some ASUS notebooks included Splashtop OS embedded into their NAND flash memory ICs. However, the idea of including an operating system along with BIOS in the ROM of a PC is not new; in the 1980s, Microsoft offered a ROM option for MS-DOS, and it was included in the ROMs of some PC clones such as the Tandy 1000 HX. Another type of firmware chip was found on the IBM PC AT and early compatibles. In the AT, the keyboard interface was controlled by a microcontroller with its own programmable memory. On the IBM AT, that was a 40-pin socketed device, while some manufacturers used an EPROM version of this chip which resembled an EPROM. This controller was also assigned the A20 gate function to manage memory above the one-megabyte range; occasionally an upgrade of this "keyboard BIOS" was necessary to take advantage of software that could use upper memory. The BIOS may contain components such as the Memory Reference Code (MRC), which is responsible for the memory initialization (e.g. SPD and memory timings initialization). Modern BIOS includes Intel Management Engine or AMD Platform Security Processor firmware. Vendors and products IBM published the entire listings of the BIOS for its original PC, PC XT, PC AT, and other contemporary PC models, in an appendix of the IBM PC Technical Reference Manual for each machine type. The effect of the publication of the BIOS listings is that anyone can see exactly what a definitive BIOS does and how it does it. In May 1984 Phoenix Software Associates released its first ROM-BIOS, which enabled OEMs to build essentially fully compatible clones without having to reverse-engineer the IBM PC BIOS themselves, as Compaq had done for the Portable, helping fuel the growth in the PC-compatibles industry and sales of non-IBM versions of DOS. And the first American Megatrends (AMI) BIOS was released on 1986. New standards grafted onto the BIOS are usually without complete public documentation or any BIOS listings. As a result, it is not as easy to learn the intimate details about the many non-IBM additions to BIOS as about the core BIOS services. Most PC motherboard suppliers licensed a BIOS "core" and toolkit from a commercial third party, known as an "independent BIOS vendor" or IBV. The motherboard manufacturer then customized this BIOS to suit its own hardware. For this reason, updated BIOSes are normally obtained directly from the motherboard manufacturer. Former major BIOS vendors included American Megatrends (AMI), Insyde Software, Phoenix Technologies, Byosoft, Award Software, and Microid Research. Microid Research and Award Software were acquired by Phoenix Technologies in 1998; Phoenix later phased out the Award brand name. General Software, which was also acquired by Phoenix in 2007, sold BIOS for embedded systems based on Intel processors. The open-source community increased their effort to develop a replacement for proprietary BIOSes and their future incarnations with an open-sourced counterpart through the libreboot, coreboot and OpenBIOS/Open Firmware projects. AMD provided product specifications for some chipsets, and Google is sponsoring the project. Motherboard manufacturer Tyan offers coreboot next to the standard BIOS with their Opteron line of motherboards. Security EEPROM and Flash memory chips are advantageous because they can be easily updated by the user; it is customary for hardware manufacturers to issue BIOS updates to upgrade their products, improve compatibility and remove bugs. However, this advantage had the risk that an improperly executed or aborted BIOS update could render the computer or device unusable. To avoid these situations, more recent BIOSes use a "boot block"; a portion of the BIOS which runs first and must be updated separately. This code verifies if the rest of the BIOS is intact (using hash checksums or other methods) before transferring control to it. If the boot block detects any corruption in the main BIOS, it will typically warn the user that a recovery process must be initiated by booting from removable media (floppy, CD or USB flash drive) so the user can try flashing the BIOS again. Some motherboards have a backup BIOS (sometimes referred to as DualBIOS boards) to recover from BIOS corruptions. There are at least five known BIOS attack viruses, two of which were for demonstration purposes. The first one found in the wild was Mebromi, targeting Chinese users. The first BIOS virus was BIOS Meningitis, which instead of erasing BIOS chips it infected them. BIOS Meningitis has relatively harmless, compared to a virus like CIH. The second BIOS virus was CIH, also known as the "Chernobyl Virus", which was able to erase flash ROM BIOS content on compatible chipsets. CIH appeared in mid-1998 and became active in April 1999. Often, infected computers could no longer boot, and people had to remove the flash ROM IC from the motherboard and reprogram it. CIH targeted the then-widespread Intel i430TX motherboard chipset and took advantage of the fact that the Windows 9x operating systems, also widespread at the time, allowed direct hardware access to all programs. Modern systems are not vulnerable to CIH because of a variety of chipsets being used which are incompatible with the Intel i430TX chipset, and also other flash ROM IC types. There is also extra protection from accidental BIOS rewrites in the form of boot blocks which are protected from accidental overwrite or dual and quad BIOS equipped systems which may, in the event of a crash, use a backup BIOS. Also, all modern operating systems such as FreeBSD, Linux, macOS, Windows NT-based Windows OS like Windows 2000, Windows XP and newer, do not allow user-mode programs to have direct hardware access. As a result, as of 2008, CIH has become essentially harmless, at worst causing annoyance by infecting executable files and triggering antivirus software. Other BIOS viruses remain possible, however; since most Windows home users without Windows Vista/7's UAC run all applications with administrative privileges, a modern CIH-like virus could in principle still gain access to hardware without first using an exploit. The operating system OpenBSD prevents all users from having this access and the grsecurity patch for the Linux kernel also prevents this direct hardware access by default, the difference being an attacker requiring a much more difficult kernel level exploit or reboot of the machine. The third BIOS virus was a technique presented by John Heasman, principal security consultant for UK-based Next-Generation Security Software. In 2006, at the Black Hat Security Conference, he showed how to elevate privileges and read physical memory, using malicious procedures that replaced normal ACPI functions stored in flash memory. The fourth BIOS virus was a technique called "Persistent BIOS infection." It appeared in 2009 at the CanSecWest Security Conference in Vancouver, and at the SyScan Security Conference in Singapore. Researchers Anibal Sacco and Alfredo Ortega, from Core Security Technologies, demonstrated how to insert malicious code into the decompression routines in the BIOS, allowing for nearly full control of the PC at start-up, even before the operating system is booted. The proof-of-concept does not exploit a flaw in the BIOS implementation, but only involves the normal BIOS flashing procedures. Thus, it requires physical access to the machine, or for the user to be root. Despite these requirements, Ortega underlined the profound implications of his and Sacco's discovery: "We can patch a driver to drop a fully working rootkit. We even have a little code that can remove or disable antivirus." Mebromi is a trojan which targets computers with AwardBIOS, Microsoft Windows, and antivirus software from two Chinese companies: Rising Antivirus and Jiangmin KV Antivirus. Mebromi installs a rootkit which infects the Master boot record. In a December 2013 interview with 60 Minutes, Deborah Plunkett, Information Assurance Director for the US National Security Agency claimed the NSA had uncovered and thwarted a possible BIOS attack by a foreign nation state, targeting the US financial system. The program cited anonymous sources alleging it was a Chinese plot. However follow-up articles in The Guardian, The Atlantic, Wired and The Register refuted the NSA's claims. Newer Intel platforms have Intel Boot Guard (IBG) technology enabled, this technology will check the BIOS digital signature at startup, and the IBG public key is fused into the PCH. End users can't disable this function. Alternatives and successors Unified Extensible Firmware Interface (UEFI) supplements the BIOS in many new machines. Initially written for the Intel Itanium architecture, UEFI is now available for x86 and ARM architecture platforms; the specification development is driven by the Unified EFI Forum, an industry Special Interest Group. EFI booting has been supported in only Microsoft Windows versions supporting GPT, the Linux kernel 2.6.1 and later, and macOS on Intel-based Macs. , new PC hardware predominantly ships with UEFI firmware. The architecture of the rootkit safeguard can also prevent the system from running the user's own software changes, which makes UEFI controversial as a legacy BIOS replacement in the open hardware community. Also, Windows 11 requires UEFI to boot. Other alternatives to the functionality of the "Legacy BIOS" in the x86 world include coreboot and libreboot. Some servers and workstations use a platform-independent Open Firmware (IEEE-1275) based on the Forth programming language; it is included with Sun's SPARC computers, IBM's RS/6000 line, and other PowerPC systems such as the CHRP motherboards, along with the x86-based OLPC XO-1. As of at least 2015, Apple has removed legacy BIOS support from MacBook Pro computers. As such the BIOS utility no longer supports the legacy option, and prints "Legacy mode not supported on this system". In 2017, Intel announced that it would remove legacy BIOS support by 2020. Since 2019, new Intel platform OEM PCs no longer support the legacy option. See also Double boot Extended System Configuration Data (ESCD) Input/Output Control System Advanced Configuration and Power Interface (ACPI) Ralf Brown's Interrupt List (RBIL) interrupts, calls, interfaces, data structures, memory and port addresses, and processor opcodes for the x86 architecture System Management BIOS (SMBIOS) Unified Extensible Firmware Interface (UEFI) Notes References Further reading BIOS Disassembly Ninjutsu Uncovered, 1st edition, a freely available book in PDF format More Power To Firmware, free bonus chapter to the Mac OS X Internals: A Systems Approach book External links CP/M technology DOS technology Windows technology

Operating System (OS)

OpenServer Xinuos OpenServer, previously SCO UNIX and SCO Open Desktop (SCO ODT), is a closed source computer operating system developed by Santa Cruz Operation (SCO), later acquired by SCO Group, and now owned by Xinuos. Early versions of OpenServer were based on UNIX System V, while the later OpenServer 10 is based on FreeBSD 10. History SCO UNIX/SCO Open Desktop SCO UNIX was the successor to the Santa Cruz Operation's variant of Microsoft Xenix, derived from UNIX System V Release 3.2 with an infusion of Xenix device drivers and utilities. SCO UNIX System V/386 Release 3.2.0 was released in 1989, as the commercial successor to SCO Xenix. The base operating system did not include TCP/IP networking or X Window System graphics; these were available as optional extra-cost add-on packages. Shortly after the release of this bare OS, SCO shipped an integrated product under the name of SCO Open Desktop, or ODT. 1994 saw the release of SCO MPX, an add-on SMP package. At the same time, AT&T completed its merge of Xenix, BSD, SunOS, and UNIX System V Release 3 features into UNIX System V Release 4. SCO UNIX remained based on System V Release 3, but eventually added home-grown versions of most of the features of Release 4. The 1992 releases of SCO UNIX 3.2v4.0 and Open Desktop 2.0 added support for long file names and symbolic links. The next major version, OpenServer Release 5.0.0, released in 1995, added support for ELF executables and dynamically linked shared objects, and made many kernel structures dynamic. SCO OpenServer SCO OpenServer 5, released in 1995, would become SCO's primary product and serve as the basis for products like PizzaNet (the first Internet-based food delivery system done in partnership with Pizza Hut) and SCO Global Access, an Internet gateway server based on Open Desktop Lite. Due to its large installed base, SCO OpenServer 5 continues to be actively maintained by SCO with major updates having occurred as recently as April 2009. SCO OpenServer 6, based on the merging of AT&T UNIX System V Release 4.2MP and UnixWare 7, was initially released by The SCO Group in 2005. It includes support for large files, increased memory, and multi-threaded kernel (light-weight processes). This merged codebase is referred to as UNIX System V Release 5 (SVR5) and was used only by SCO for OpenServer 6; SVR5 is not used by any other major developer or reseller. SCO OpenServer 6 contains the UnixWare 7's SVR5 kernel integrated with SCO OpenServer 5 application and binary compatibility, OpenServer 5 system administration, and OpenServer 5 user environments. SCO OpenServer has primarily been sold into the small and medium business (SMB) market. It is widely used in small offices, point of sale (POS) systems, replicated sites, and backoffice database server deployments. Prominent larger SCO OpenServer customers include McDonald's, Taco Bell, Big O Tires, Pizza Hut, Costco pharmacy, NASDAQ, The Toronto Stock Exchange, Banco do Brasil, many banks in Russia and China, and the railway system of India. UnixWare merger SCO purchased the right to distribute the UnixWare system and its System V Release 4 code base from Novell in 1995. SCO was eventually able to re-use some code from that version of UnixWare in later releases of OpenServer. Until Release 6, this came primarily in the compilation system and the UDI driver framework and the USB subsystem written to it. By the end of the 1990s, there were around 15,000 value-added resellers (VARs) around the world who provided solutions for customers of SCO's Unix systems. SCO announced on August 2, 2000, that it would sell its Server Software and Services Divisions, as well as UnixWare and OpenServer technologies, to Caldera Systems, Inc. The purchase was completed in May 2001. The remaining part of the SCO company, the Tarantella Division, changed its name to Tarantella, Inc., while Caldera Systems became Caldera International, and subsequently in 2002, the SCO Group. Under The SCO Group The SCO Group continued the development and maintenance of OpenServer. On June 22, 2005, OpenServer 6.0 was released, codenamed "Legend", the first release in the new 6.0.x branch. SCO OpenServer 6 is based on the UNIX System V Release 5 kernel, a merged codebase of UNIX System V Release 4.2MP and UnixWare 7. OpenServer 6.0 features multi-threading application support for C, C++, and Java applications through the POSIX interface. OpenServer 6 features kernel-level threading (not found in 5.0.x). Some improvements over OpenServer 5 include improved SMP support (support for up to 32 processors), support for files over a terabyte on a partition (larger network files supported through NFSv3), better file system performance, and support for up to 64GB of memory. OpenServer 6.0 maintains backward-compatibility for applications developed for Xenix 286 onwards. The SCO Group went bankrupt in 2011, after a long series of legal battles. UnXis / Xinuos (2011–present) The rights to OpenServer, as well as UnixWare, were acquired by UnXis in 2011, which was later renamed Xinuos. In June 2015, Xinuos announced OpenServer 10, which is based on the FreeBSD 10 operating system. Simultaneously, Xinuos introduced a migration path for existing customers using older OS products. In December 2015, Xinuos released "definitive" versions of OpenServer 5, OpenServer 6, and UnixWare 7. In December 2017, Xinuos released "Definitive 2018" versions of OpenServer 6 and UnixWare 7, and in October 2018 OpenServer 5 Definitive 2018 was released. The "Definitive 2018" releases were a commitment by Xinuos to keep the legacy OS's updated and supported protecting the applications that customers need to continue to run. The Definitive 2018 products contain major updates over the Definitive releases and a soon to be announced updated development kit which will make it easier to compile current packages for the Definitive 2018 products. Xinuos has continued to provide updates for the new flagship operating system OpenServer 10. Versions See also Santa Cruz Operation SCO v. Novell References External links SCO OpenServer 6.0 (deprecated) home page SCO OpenServer 5.0.7 (deprecated) home page SCO OS FAQ (3.2v4.2 and 3.2v5.0.x) Review in Linux Journal FreeBSD UNIX System V

Operating System (OS)

OpenSolaris for System z OpenSolaris for System z is a discontinued port of the OpenSolaris operating system to the IBM System z line of mainframe computers. History OpenSolaris is based on Solaris, which was originally released by Sun Microsystems in 1991. Sun released the bulk of the Solaris system source code in OpenSolaris on 14 June 2005, which made it possible for developers to create other OpenSolaris distributions. Sine Nomine Associates began a project to bring OpenSolaris to the IBM mainframe in July, 2006. The project was named Sirius (in analogy to the Polaris project to port OpenSolaris to PowerPC). In April, 2007, Sine Nomine presented an initial progress report at IBM's System z Technical Expo conference. At the Gartner Data Center Conference in Las Vegas, Nevada in late 2007, Sine Nomine demonstrated OpenSolaris running on IBM System z under z/VM. It was there that David Boyes of Sine Nomine stated that OpenSolaris for System z would be available "soon." At the SHARE conference on 13 August 2008, Neale Ferguson of Sine Nomine Associates presented an update on the progress of OpenSolaris for System z. This presentation included a working demonstration of OpenSolaris for System z. During this presentation he stated that while OpenSolaris is "not ready for prime-time" they hoped to have a version available to the public for testing "in a matter of weeks rather than months." In October, 2008, Sine Nomine Associates released the first "prototype" (it lacks a number of features such as DTrace, Solaris Containers and the ability to act as an NFS server) of OpenSolaris for System z to the public. OpenSolaris for System z has a project page at OpenSolaris.org. OpenSolaris for System z is available for download at no charge, and is governed by the same open source license terms as OpenSolaris for other platforms. All source code is available; there are no OCO (object code only) modules. The port uses z/Architecture 64-bit addressing and therefore requires an IBM System z mainframe. Because the port depends on recently defined z/Architecture processor instructions, it requires a System z9 or later mainframe model and will not run on older machines. It also will not run on the release version of Hercules mainframe emulator, the needed changes are included in the SVN version 5470 of Hercules. It also requires the paravirtualization features provided by z/VM; it will not run on "bare metal" or in a logical partition (LPAR) without the z/VM hypervisor at Version 5.3 level or later. Also, because OpenSolaris uses a new network DIAGNOSE instruction, PTF VM64466 or VM64471 must be applied to z/VM to provide support for that instruction. On 18 November 2008, IBM authorized the use of IFL processors to run OpenSolaris for System z workloads. The Register reported in March 2010 an email from an insider saying that: See also Linux on IBM Z UTS (Mainframe UNIX) References External links OpenSolaris Project: System z (source code and project home) Sine Nomine Associates OpenSolaris for System z Distribution (binary code download site) [!Page Not Found!] OpenSolaris IBM mainframe operating systems VM (operating system)

Operating System (OS)

Oracle Solaris Solaris is a proprietary Unix operating system originally developed by Sun Microsystems. After the Sun acquisition by Oracle in 2010, it was renamed Oracle Solaris. Solaris superseded the company's earlier SunOS in 1993, and became known for its scalability, especially on SPARC systems, and for originating many innovative features such as DTrace, ZFS and Time Slider. Solaris supports SPARC and x86-64 workstations and servers from Oracle and other vendors. Solaris was registered as compliant with UNIX 03 until 29 April 2019. Historically, Solaris was developed as proprietary software. In June 2005, Sun Microsystems released most of the codebase under the CDDL license, and founded the OpenSolaris open-source project. With OpenSolaris, Sun wanted to build a developer and user community around the software. After the acquisition of Sun Microsystems in January 2010, Oracle decided to discontinue the OpenSolaris distribution and the development model. In August 2010, Oracle discontinued providing public updates to the source code of the Solaris kernel, effectively turning Solaris 11 back into a closed source proprietary operating system. Following that, OpenSolaris was forked as illumos and is alive through several illumos distributions. In 2011, the Solaris 11 kernel source code leaked to BitTorrent. Through the Oracle Technology Network (OTN), industry partners can gain access to the in-development Solaris source code. Solaris is developed under a proprietary development model, and only the source for open-source components of Solaris 11 is available for download from Oracle. History In 1987, AT&T Corporation and Sun announced that they were collaborating on a project to merge the most popular Unix variants on the market at that time: Berkeley Software Distribution, UNIX System V, and Xenix. This became Unix System V Release 4 (SVR4). On September 4, 1991, Sun announced that it would replace its existing BSD-derived Unix, SunOS 4, with one based on SVR4. This was identified internally as SunOS 5, but a new marketing name was introduced at the same time: Solaris 2. The justification for this new overbrand was that it encompassed not only SunOS, but also the OpenWindows graphical user interface and Open Network Computing (ONC) functionality. Although SunOS 4.1.x micro releases were retroactively named Solaris 1 by Sun, the Solaris name is used almost exclusively to refer only to the releases based on SVR4-derived SunOS 5.0 and later. For releases based on SunOS 5, the SunOS minor version is included in the Solaris release number. For example, Solaris 2.4 incorporates SunOS 5.4. After Solaris 2.6, the 2. was dropped from the release name, so Solaris 7 incorporates SunOS 5.7, and the latest release SunOS 5.11 forms the core of Solaris 11.4. Although SunSoft stated in its initial Solaris 2 press release their intent to eventually support both SPARC and x86 systems, the first two Solaris 2 releases, 2.0 and 2.1, were SPARC-only. An x86 version of Solaris 2.1 was released in June 1993, about 6 months after the SPARC version, as a desktop and uniprocessor workgroup server operating system. It included the Wabi emulator to support Windows applications. At the time, Sun also offered the Interactive Unix system that it had acquired from Interactive Systems Corporation. In 1994, Sun released Solaris 2.4, supporting both SPARC and x86 systems from a unified source code base. On September 2, 2017, Simon Phipps, a former Sun Microsystems employee not hired by Oracle in the acquisition, reported on Twitter that Oracle had laid off the Solaris core development staff, which many interpreted as sign that Oracle no longer intended to support future development of the platform. While Oracle did have a large layoff of Solaris development engineering staff, development continued and Solaris 11.4 was released in 2018. Supported architectures Solaris uses a common code base for the platforms it supports: SPARC and i86pc (which includes both x86 and x86-64). Solaris has a reputation for being well-suited to symmetric multiprocessing, supporting a large number of CPUs. It has historically been tightly integrated with Sun's SPARC hardware (including support for 64-bit SPARC applications since Solaris 7), with which it is marketed as a combined package. This has led to more reliable systems, but at a cost premium compared to commodity PC hardware. However, it has supported x86 systems since Solaris 2.1 and 64-bit x86 applications since Solaris 10, allowing Sun to capitalize on the availability of commodity 64-bit CPUs based on the x86-64 architecture. Sun has heavily marketed Solaris for use with both its own "x64" workstations and servers based on AMD Opteron and Intel Xeon processors, as well as x86 systems manufactured by companies such as Dell, Hewlett-Packard, and IBM. As of 2009, the following vendors support Solaris for their x86 server systems: Dell – will "test, certify, and optimize Solaris and OpenSolaris on its rack and blade servers and offer them as one of several choices in the overall Dell software menu" Intel Hewlett Packard Enterprise – distributes and provides software technical support for Solaris on BL, DL, and SL platforms Fujitsu Siemens Other platforms Solaris 2.5.1 included support for the PowerPC platform (PowerPC Reference Platform), but the port was canceled before the Solaris 2.6 release. In January 2006, a community of developers at Blastwave began work on a PowerPC port which they named Polaris. In October 2006, an OpenSolaris community project based on the Blastwave efforts and Sun Labs' Project Pulsar, which re-integrated the relevant parts from Solaris 2.5.1 into OpenSolaris, announced its first official source code release. A port of Solaris to the Intel Itanium architecture was announced in 1997 but never brought to market. On November 28, 2007, IBM, Sun, and Sine Nomine Associates demonstrated a preview of OpenSolaris for System z running on an IBM System z mainframe under z/VM, called Sirius (in analogy to the Polaris project, and also due to the primary developer's Australian nationality: HMS Sirius of 1786 was a ship of the First Fleet to Australia). On October 17, 2008, a prototype release of Sirius was made available and on November 19 the same year, IBM authorized the use of Sirius on System z Integrated Facility for Linux (IFL) processors. Solaris also supports the Linux platform application binary interface (ABI), allowing Solaris to run native Linux binaries on x86 systems. This feature is called Solaris Containers for Linux Applications (SCLA), based on the branded zones functionality introduced in Solaris 10 8/07. Installation and usage options Solaris can be installed from various pre-packaged software groups, ranging from a minimalistic Reduced Network Support to a complete Entire Plus OEM. Installation of Solaris is not necessary for an individual to use the system. Additional software, like Apache, MySQL, etc. can be installed as well in a packaged form from sunfreeware and OpenCSW. Solaris can be installed from physical media or a network for use on a desktop or server, or be used without installing on a desktop or server. Desktop environments Early releases of Solaris used OpenWindows as the standard desktop environment. In Solaris 2.0 to 2.2, OpenWindows supported both NeWS and X applications, and provided backward compatibility for SunView applications from Sun's older desktop environment. NeWS allowed applications to be built in an object-oriented way using PostScript, a common printing language released in 1982. The X Window System originated from MIT's Project Athena in 1984 and allowed for the display of an application to be disconnected from the machine where the application was running, separated by a network connection. Sun's original bundled SunView application suite was ported to X. Sun later dropped support for legacy SunView applications and NeWS with OpenWindows 3.3, which shipped with Solaris 2.3, and switched to X11R5 with Display Postscript support. The graphical look and feel remained based upon OPEN LOOK. OpenWindows 3.6.2 was the last release under Solaris 8. The OPEN LOOK Window Manager (olwm) with other OPEN LOOK specific applications were dropped in Solaris 9, but support libraries were still bundled, providing long term binary backwards compatibility with existing applications. The OPEN LOOK Virtual Window Manager (olvwm) can still be downloaded for Solaris from sunfreeware and works on releases as recent as Solaris 10. Sun and other Unix vendors created an industry alliance to standardize Unix desktops. As a member of the Common Open Software Environment (COSE) initiative, Sun helped co-develop the Common Desktop Environment (CDE). This was an initiative to create a standard Unix desktop environment. Each vendor contributed different components: Hewlett-Packard contributed the window manager, IBM provided the file manager, and Sun provided the e-mail and calendar facilities as well as drag-and-drop support (ToolTalk). This new desktop environment was based upon the Motif look and feel and the old OPEN LOOK desktop environment was considered legacy. CDE unified Unix desktops across multiple open system vendors. CDE was available as an unbundled add-on for Solaris 2.4 and 2.5, and was included in Solaris 2.6 through 10. In 2001, Sun issued a preview release of the open-source desktop environment GNOME 1.4, based on the GTK+ toolkit, for Solaris 8. Solaris 9 8/03 introduced GNOME 2.0 as an alternative to CDE. Solaris 10 includes Sun's Java Desktop System (JDS), which is based on GNOME and comes with a large set of applications, including StarOffice, Sun's office suite. Sun describes JDS as a "major component" of Solaris 10. The Java Desktop System is not included in Solaris 11 which instead ships with a stock version of GNOME. Likewise, CDE applications are no longer included in Solaris 11, but many libraries remain for binary backwards compatibility. The open source desktop environments KDE and Xfce, along with numerous other window managers, also compile and run on recent versions of Solaris. Sun was investing in a new desktop environment called Project Looking Glass since 2003. The project has been inactive since late 2006. License Traditional operating system license (1982 to 2004) For versions up to 2005 (Solaris 9), Solaris was licensed under a license that permitted a customer to buy licenses in bulk, and install the software on any machine up to a maximum number. The key license grant was: In addition, the license provided a "License to Develop" granting rights to create derivative works, restricted copying to only a single archival copy, disclaimer of warranties, and the like. The license varied only little through 2004. Open source (2005 until March 2010) From 2005–10, Sun began to release the source code for development builds of Solaris under the Common Development and Distribution License (CDDL) via the OpenSolaris project. This code was based on the work being done for the post-Solaris 10 release (code-named "Nevada"; eventually released as Oracle Solaris 11). As the project progressed, it grew to encompass most of the necessary code to compile an entire release, with a few exceptions. Post-Oracle closed source (March 2010 to present) When Sun was acquired by Oracle in 2010, the OpenSolaris project was discontinued after the board became unhappy with Oracle's stance on the project. In March 2010, the previously freely available Solaris 10 was placed under a restrictive license that limited the use, modification and redistribution of the operating system. The license allowed the user to download the operating system free of charge, through the Oracle Technology Network, and use it for a 90-day trial period. After that trial period had expired the user would then have to purchase a support contract from Oracle to continue using the operating system. With the release of Solaris 11 in 2011, the license terms changed again. The new license allows Solaris 10 and Solaris 11 to be downloaded free of charge from the Oracle Technology Network and used without a support contract indefinitely; however, the license only expressly permits the user to use Solaris as a development platform and expressly forbids commercial and "production" use. Educational use is permitted in some circumstances. From the OTN license: When Solaris is used without a support contract it can be upgraded to each new "point release"; however, a support contract is required for access to patches and updates that are released monthly. Version history Notable features of Solaris include DTrace, Doors, Service Management Facility, Solaris Containers, Solaris Multiplexed I/O, Solaris Volume Manager, ZFS, and Solaris Trusted Extensions. Updates to Solaris versions are periodically issued. In the past, these were named after the month and year of their release, such as "Solaris 10 1/13"; as of Solaris 11, sequential update numbers are appended to the release name with a period, such as "Oracle Solaris 11.4". In ascending order, the following versions of Solaris have been released: A more comprehensive summary of some Solaris versions is also available. Solaris releases are also described in the Solaris 2 FAQ. Development release The underlying Solaris codebase has been under continuous development since work began in the late 1980s on what was eventually released as Solaris 2.0. Each version such as Solaris 10 is based on a snapshot of this development codebase, taken near the time of its release, which is then maintained as a derived project. Updates to that project are built and delivered several times a year until the next official release comes out. The Solaris version under development by Sun since the release of Solaris 10 in 2005, was codenamed Nevada, and is derived from what is now the OpenSolaris codebase. In 2003, an addition to the Solaris development process was initiated. Under the program name Software Express for Solaris (or just Solaris Express), a binary release based on the current development basis was made available for download on a monthly basis, allowing anyone to try out new features and test the quality and stability of the OS as it progressed to the release of the next official Solaris version. A later change to this program introduced a quarterly release model with support available, renamed Solaris Express Developer Edition (SXDE). In 2007, Sun announced Project Indiana with several goals, including providing an open source binary distribution of the OpenSolaris project, replacing SXDE. The first release of this distribution was OpenSolaris 2008.05. The Solaris Express Community Edition (SXCE) was intended specifically for OpenSolaris developers. It was updated every two weeks until it was discontinued in January 2010, with a recommendation that users migrate to the OpenSolaris distribution. Although the download license seen when downloading the image files indicates its use is limited to personal, educational and evaluation purposes, the license acceptance form displayed when the user actually installs from these images lists additional uses including commercial and production environments. SXCE releases terminated with build 130 and OpenSolaris releases terminated with build 134 a few weeks later. The next release of OpenSolaris based on build 134 was due in March 2010, but it was never fully released, though the packages were made available on the package repository. Instead, Oracle renamed the binary distribution Solaris 11 Express, changed the license terms and released build 151a as 2010.11 in November 2010. Open source derivatives Current illumos – A fully open source fork of the project, started in 2010 by a community of Sun OpenSolaris engineers and Nexenta OS. 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 de facto OpenSolaris distribution installed on production servers where security and bug fixes are required free of charge." SchilliX – The first LiveCD released after OpenSolaris code was opened to public. napp-it – A webmanaged ZFS storage appliance based on Solaris and the free forks like OmniOS with a Free and Pro edition. NexentaStor – Optimized for storage workloads, based on Nexenta OS. Dyson – illumos kernel with GNU userland and packages from Debian. Project is no longer active and the website is offline. SmartOS – Virtualization centered derivative from Joyent. Discontinued OpenSolaris – A project initiated by Sun Microsystems, discontinued after the acquisition by Oracle. Nexenta OS (discontinued October 31, 2012) – First distribution based on Ubuntu userland with Solaris-derived kernel. StormOS (discontinued September 14, 2012) – A lightweight desktop OS based on Nexenta OS and Xfce. MartUX – The first SPARC distribution of OpenSolaris, with an alpha prototype released by Martin Bochnig in April 2006. It was distributed as a Live CD but is later available only on DVD as it has had the Blastwave community software added. Its goal was to become a desktop operating system. The first SPARC release was a small Live CD, released as marTux_0.2 Live CD in summer of 2006, the first straight OpenSolaris distribution for SPARC (not to be confused with GNOME metacity theme). It was later re-branded as MartUX and the next releases included full SPARC installers in addition to the Live media. Much later, MartUX was re-branded as OpenSXCE when it moved to the first OpenSolaris release to support both SPARC and Intel architectures after Sun was acquired by Oracle. MilaX – A small Live CD/Live USB with minimal set of packages to fit a 90 MB image. EON ZFS Storage – A NAS implementation targeted at embedded systems. Jaris OS – Live DVD and also installable. Pronounced according to the IPA but in English as Yah-Rees. This distribution has been heavily modified to fully support a version of Wine called Madoris that can install and run Windows programs at native speed. Jaris stands for "Japanese Solaris". Madoris is a combination of the Japanese word for Windows "mado" and Solaris. OpenSXCE – An OpenSolaris distribution release for both 32-bit and 64-bit x86 platforms and SPARC microprocessors, initially produced from OpenSolaris source code repository, ported to the illumos source code repository to form OpenIndiana's first SPARC distribution. Notably, the first OpenSolaris distribution with illumos source for SPARC based upon OpenIndiana, OpenSXCE finally moved to a new source code repository, based upon DilOS. Reception Robert Lipschutz and Gregg Harrington from PC Magazine reviewed Solaris 9 in 2002: Robert Lipschutz also reviewed Solaris 10: Tom Henderson reviewed Solaris 10 for Network World: Robert Escue for OSNews: Thomas Greene for The Register: See also IBM AIX HP-UX illumos Trusted Solaris Oracle VM Server for SPARC References External links Solaris Documentation Lifetime Support Policy: Oracle and Sun System Software and Operating Systems SunHELP – Sun/Solaris News, References, and Information Nikolai Bezroukov. Solaris vs. Linux: Ecosystem-based Approach and Framework for the Comparison in Large Enterprise Environments – Large Softpanorama article comparing Solaris 10 and Linux 2.6 – Solaris information site by Michael Holve 1993 software Formerly free software OpenSolaris Oracle Corporation Oracle software Proprietary operating systems Sun Microsystems software UNIX System V X86 operating systems

Operating System (OS)

OS X Yosemite OS X Yosemite ( ; version 10.10) is the eleventh major release of macOS, Apple Inc.'s desktop and server operating system for Macintosh computers. OS X Yosemite was announced and released to developers on June 2, 2014, at WWDC 2014 and released to public beta testers on July 24, 2014. Yosemite was released to consumers on October 16, 2014. Following the Northern California landmark-based naming scheme introduced with OS X Mavericks, Yosemite is named after the national park. System requirements All Macintosh products capable of running OS X Mountain Lion (v10.8.x) are able to run Yosemite as the two operating systems have the same requirements. However, to take full advantage of the Handoff feature, additional minimum system requirements include a Mac with Bluetooth LE (Bluetooth 4.0). As with Mavericks and Mountain Lion, 2GB of RAM, 8GB of available storage, and OS X 10.6.8 (Snow Leopard) or later are required. These are the models that are compatible with OS X Yosemite (with exceptions): iMac (Mid 2007 or later) MacBook (Aluminum Late 2008 and Early 2009 or later) MacBook Pro (13-inch, Mid 2009 or later; 15-inch, Mid/Late 2007 or later; 17-inch, Late 2007 or later) MacBook Air (Late 2008 or later) Mac Mini (Early 2009 or later) Mac Pro (Early 2008 or later) (Can run on a mid-2006 version if one upgrades to a supported graphics chip and utilizes a custom bootloader) Xserve (Early 2009) These are the models that support new features such as Handoff, Instant Hotspot as well as AirDrop between Mac computers and iOS devices: MacBook Air (Mid 2012 or later) MacBook Pro (Mid 2012 or later) iMac (Late 2012 or later) Mac Mini (Late 2012 or later) Mac Pro (Late 2013) Features Design Yosemite introduced a major overhaul of OS X's user interface, emphasizing flat graphic design over skeuomorphism, following the aesthetic introduced with iOS 7. It is the first major redesign of the OS X user interface since 10.5 Leopard. Other changes include thinner fonts and blurred translucency effects. Some icons have been changed to correspond with those of iOS 7 and iOS 8. Yosemite maintains the OS X desktop metaphor. Other design changes include new icons, light and dark color schemes, and the replacement of Lucida Grande with Helvetica Neue as the default system typeface. It was the only macOS version to use Helvetica Neue as the default typeface, as in El Capitan it was again changed, this time to Apple's own, newly-designed San Francisco typeface. The Dock is now a 2D translucent rectangle instead of a skeuomorphic glass shelf, reminiscent of the Dock design used in early versions of OS X through Tiger and in iOS since iOS 7. Continuity Many of Yosemite's new features focus on the theme of continuity, increasing its integration with other Apple platforms and services such as iOS and iCloud. The Handoff functionality allows the operating system to integrate with iOS 8 devices over Bluetooth LE and Wi-Fi; users can place and answer phone calls using their iPhone as a conduit, send and receive text messages, activate personal hotspots, or load items being worked on in a mobile app (such as Mail drafts or Numbers spreadsheets) directly into their desktop equivalent. Notification Center Notification Center features a new "Today" view, similar to that in iOS. The Today view can display information and updates from various sources, along with widgets. The widgets in the Today view are similar to those of iOS 8. Photos As of OS X 10.10.3, Photos replaces both iPhoto and Aperture. It uses iCloud Photo Library to upload all the user's photos across their devices. Applications found on OS X 10.10 Yosemite AirPort Utility App Store Archive Utility Audio MIDI Setup Automator Bluetooth File Exchange Boot Camp Assistant Calculator Calendar Chess ColorSync Utility Console Contacts Dictionary Digital Color Meter Disk Utility DVD Player FaceTime Font Book Game Center GarageBand (may not be pre-installed) Grab Grapher iBooks (now Apple Books) iMovie (may not be pre-installed) iTunes Image Capture Ink (can only be accessed by connecting a graphics tablet to your Mac) Keychain Access Keynote (may not be pre-installed) Maps Messages Migration Assistant Notes Notification Center Numbers (may not be pre-installed) Pages (may not be pre-installed) Photo Booth Preview QuickTime Player Reminders Script Editor Stickies System Information Terminal TextEdit Time Machine VoiceOver Utility X11/XQuartz (may not be pre-installed) Other Spotlight is a more prominent part of the operating system; it now displays its search box in the center of the screen and can include results from online sources, including Bing, Maps, and Wikipedia. Stock applications such as Safari and Mail have been updated. In particular, many security features have been added to Safari, such as a custom history clearing option that lets users clear history, cookies, and other data from the previous hour, day, or two days. In addition, Apple added DuckDuckGo to its search offerings, a non-tracking search engine that doesn’t store users’ data. Safari allows you to remotely close tabs from an iOS device. Safari now supports browsing in private browsing mode with certain windows (as opposed to all the windows having to be either in or out of private browsing). The green "zoom" button on windows now has a different function in applications that support full-screen mode. Instead of simply enlarging the window, the button now enters full-screen mode, eliminating the full-screen button at the top-right corner of windows that has been present since Mac OS X Lion. However, holding the Option key (⌥) while clicking the zoom button or double-clicking on the window chrome continues to invoke the original behavior. JavaScript for Automation (JXA) is the new system-wide support for scripting with JavaScript, built upon JavaScriptCore and the Open Scripting Architecture. It features an Objective-C bridge which enables entire Cocoa applications to be programmed in JavaScript. Along with other framework changes, CloudKit was integrated in this release. CloudKit functions as a Mobile Backend as a Service (MBaaS) and is one method for app developers to integrate access to Apple’s iCloud servers into their apps. There is a "dark mode" in System Preferences which makes the Dock and menu bar darker. Beta testing Apple initiated a new public beta program for OS X, a practice not seen with its operating systems since 2000's Mac OS X Public Beta, which had preceded the release of Mac OS X v10.0. Yosemite is part of the OS X Beta Seed Program, a public program that allows the first 1 million users to download and test the Yosemite beta at no charge. Beta testers are required to acknowledge the potential risks involved with prerelease software, and sign a non-disclosure agreement (NDA). The program began releasing Public Betas on July 24, 2014. Six public betas of Yosemite were released. Reception On release, Yosemite received positive reviews, with users praising the simplified user interface. Programmer John Siracusa, who had reviewed every OS release, wrote for Ars Technica that "Yosemite is an aesthetic one-way valve... switching back to Mavericks after a week or two in Yosemite is like returning to iOS 6. Everything looks embarrassingly chunky, glossy, and gaudy." Macworlds review generally praised Yosemite for its design, but noted that it had found WiFi network issues and that Continuity had proved unreliable. Criticism Yosemite faced problems with network stability and the discoveryd DNS system. Because of this, Apple replaced discoveryd with the mDNSResponder system (used in Mavericks) in 10.10.4. Another notable bug experienced on Yosemite was the 'Unicode of death' problem, following a similar bug in 2013, in which a meaningless Arabic text string could crash applications using the system text-display APIs. Some users who upgraded to Yosemite complained that the Finder fails to show the contents of folders. Software developers and users have argued that Apple's yearly release schedule and development practices have compromised stability, and mean that no version of OS X is truly recommendable for users prioritizing reliability over new user interface design and features. Spotlight on Yosemite by default reports the user's current location (at the city level) and all their search queries to Apple and third parties. Reporting by Spotlight can be disabled by the user, although, even if this is done, the Safari web browser will continue to send search terms to Apple unless the function is separately disabled. Release history References External links OS X Yosemite: The Ars Technica Review 10 X86-64 operating systems 2014 software Computer-related introductions in 2014

Operating System (OS)

List of Microsoft Windows versions This is a list of Microsoft Windows versions. Microsoft Windows is a major computer operating system developed by Microsoft. Personal computer versions In this section, a client version of Windows is a version that end-users or OEMs can install on personal computers, including desktop computers, laptops, and workstations. Mobile versions Mobile versions refer to versions of Windows that can run on smartphones or personal digital assistants. Server versions Windows MultiPoint Server Windows MultiPoint Server was an operating system based on Windows Server. The final release of the operating system was Windows MultiPoint Server 2012; it was succeeded by the MultiPoint Services role in Windows Server 2016. Beginning with Windows Server version 1803, Microsoft announced that the MultiPoint Services role was no longer being developed. Device versions ARM-based tablets In 2012 and 2013, Microsoft released versions of Windows specially designed to run on ARM-based tablets; these versions of Windows were based on Windows 8 and Windows 8.1, respectively, although the standard versions could run on x86-based tablets without modification. Upon the release of Windows 10 in 2015, the ARM-specific version for large tablets was discontinued; large tablets (such as the Surface Pro 4) were only released with x86 processors and could run the full version of Windows 10. Windows 10 Mobile had the ability to be installed on smaller tablets (up to eight inches); however, very few such tablets were released, and Windows 10 Mobile mainly ended up only running on smartphones until its discontinuation. In 2017, the full version of Windows 10 gained the ability to run on ARM, rendering a specific version of Windows for ARM-based tablets unnecessary. Mixed reality and virtual reality headsets Surface Hub Windows XP-based tablets Two versions of Windows XP were released that were optimized for tablets. Beginning with Windows Vista, all tablet-specific components were included in the main version of the operating system. Embedded versions Windows CE 1.0 (November 1996) Windows CE 2.0 (September 1997) Windows CE 2.1 (1998 July) Windows CE 2.11 (1998 October) Windows CE 2.12 (1999 August) Windows CE 3.0 (June 2000), with version for smartphones and PDAs sold as Pocket PC 2000 Windows CE 4.0 (2002), with version for smartphones and PDAs sold as Pocket PC 2002 Windows CE 4.1 (2003), with version for smartphones and PDAs sold as Pocket PC 2003 Windows CE 4.2 (2004), with version for smartphones and PDAs sold as Windows Mobile 2003 SE Windows CE 5.0 (2005), with version for smartphones and PDAs sold as Windows Mobile 5.0 Windows Embedded CE 6.0 (2006) Windows Embedded Compact Windows Embedded Compact 7 Windows Embedded Compact 2013 Windows Embedded Windows NT 4.0 Embedded – Abbreviated NTe, it is an edition of Windows NT 4.0 that was aimed at computer-powered major appliances, vending machines, ATMs and other devices that cannot be considered computers per se. It is the same system as the standard Windows NT 4.0, but it comes packaged in a database of components and dependencies, from which a developer can choose individual components to build customized setup CDs and hard disk boot images. Windows NT 4.0 Embedded includes Service Pack 5. Windows XP Embedded Windows Embedded Industry Windows Embedded Automotive Windows Embedded 8 Cancelled versions Cancelled personal computer versions Cancelled mobile versions See also Microsoft Windows version history List of Microsoft codenames Comparison of Microsoft Windows versions List of Microsoft operating systems Windows 10 version history Notes References Windows Windows

Operating System (OS)

DEC BATCH-11/DOS-11 BATCH-11/DOS-11, also known simply as DOS-11, is a discontinued operating system by Digital Equipment Corporation (DEC) of Maynard, Massachusetts. The first version of DOS-11 (V08-02) was released in 1970 and was the first operating system to run on the Digital PDP-11 minicomputer. DOS-11 was not known to be easy to use even in its day and became much less used in 1973 with the release of the RT-11 operating system. Features DOS-11 included: DOS-Monitor Edit-11 (text editor) FORTRAN IV (programming language) Libr-11 (librarian) Link-11 (linker) ODT-11R (debugging program) PAL-11R (assembler) PIP (file utility package) DOS-11 came with XXDP, a diagnostics and monitor program for the PDP-11. Like other Digital operating systems, DOS-11 also had a FORTRAN-IV (Ansi-66) compiler. FORTRAN-IV was not supported on PDP-11 systems with less than 12K of memory. DOS-11 systems running in 8K and 12K configurations ran a limited version of the MACRO-11 Assembler (PAL-11R in overlaid form). The DOS-11 operating system kernel was one file called MONLIB.LCL. The LCL extension was the acronym for LInked Core Image Library (or LICIL). An LICIL could be stored on any type of media that the DOS-11 operating system was distributed on (disk, DECtape, punched tape or magnetic tape). When the LICIL file was installed (Hooked) onto a disk drive as a contiguous file, the monitor library name is changed to MONLIBCIL which could then be booted. The CIL extension was the acronym for Core Image Library. Core, was the term for the core memory systems common to the PDP-11. A Core Image Library could be created with the CILUS (Core Image Library Update and Save) program. A MONLIBCIL typically contained the resident monitor (RMON), the keyboard command routine, device drivers, EMT routines, the clock routines and the transient monitor. Legacy DOS-11 was used to compile and install early versions of the RSTS-11 and RSTS/E operating systems however it is an ancestor to the RSX-11 family of operating systems. References DEC operating systems PDP-11 Real-time operating systems 1970 software

Operating System (OS)

LOGO.SYS LOGO.SYS is a core system file used by Windows 9x operating systems to display its boot-up message. It is present and used in the Windows 95, Windows 98, and Windows ME products, instead of the Windows NT family of operating systems, such as Windows XP, Windows 2000 etc. There are three variants of the file: LOGO.SYS: is the "Starting Windows" message, with the Windows logo. The file is located in the root directory of the boot drive. This is usually , but with drive compression, like DriveSpace, this is the host drive (often ). The default LOGO.SYS file is also stored in IO.SYS and used by MS-DOS during startup if LOGO.SYS could not be found. The display of the logo can be disabled by adding a LOGO=0 setting to the Options section in the MS-DOS 7 configuration file MSDOS.SYS. LOGOW.SYS: is the "Please wait while your computer shuts down" (later "Windows is shutting down") message. The file is located in the Windows directory, which by default is . The Windows logo is shown only in Windows 95 and 98 (in Windows 95, only the Microsoft Windows 95 wordmark is displayed). Windows ME computer monitors either cut to the LOGOS.SYS screen or simply cut to black after shutting down. No error will be shown if the file cannot be found. LOGOS.SYS: is the "It is now safe to turn off your computer" message. The file is located in the Windows directory. This message is displayed when Windows has successfully shut down to MS-DOS but is not configured to return to the prompt (COMMAND.COM) again. On systems with proper ACPI support and ATX power supply, the PC may power down instead. If the file cannot be found, the same message is displayed in text mode. No error will be shown if the file cannot be found. LOGO.SYS is in fact an 8-bit RLE-encoded Windows bitmap file with a resolution of exactly 320×400 pixels at 256 colors. This is displayed in the otherwise little-used 320x400 VGA graphics mode, a compromise to allow the display of a 256-color image with high vertical (but not horizontal) resolution on all compatible systems, even those with plain VGA cards (which could only show 16 colors with high horizontal resolution) and without needing any additional graphics drivers. The mode appears, to any attached monitor, to be identical to the more common 640x400 graphics or 720x400 text modes, and is therefore stretched to a standard 4:3 aspect ratio (meaning the pixels appear to be 1.67x (2/1.2) wider than they are tall, instead of square - as they would be on a full 640x480 VGA display) on a typical 4:3 monitor of the time, and on monitors of other shapes (5:4, 16:9, etc.) when set to display standard video modes in their original aspects with letterbox borders. This lent the startup screens a peculiar, characteristic "feel" and made them more suited to certain subjects (which disguised the horizontal blockiness or made good use of the vertical resolution) than others (which accentuated it), meaning some skill was needed in choosing an image that would still be aesthetically pleasing - or even clear enough to be properly interpreted - once resized. For LOGO.SYS or the equivalent embedded image in IO.SYS, Windows will also animate the image's color information using palette rotation; the image is static, but may have the illusion of movement as colors are changed. As the files are standard RLE-compressed .BMPs (with an entirely optional custom tag segment) renamed to ".SYS", they may be opened and edited using image editing tools such as MS Paint, and the contents replaced with user-selected pictures; the only conversion needed is to change the file extension, and to ensure they are in the correct resolution and color depth (with dithering if needed). However, the process is not foolproof: Ensuring the aspect ratio is correct can be confusing, as it is usually displayed in a horizontally compressed form on a screen with square pixels (the most reliable method being to edit at full size, crop to 4:3, then resize to 320x400) The loading indicator animation was created using palette rotation. The number of palette entries to rotate is determined by the otherwise seldom used biClrImportant field of the BITMAPINFOHEADER structure. Image editing software usually discarded this data, so it was often not possible to retain it. Some logo creation utilities were specifically created to restore the cycling function and allow creating custom animations. Just like the bootsplash screens in earlier versions of Windows, there was a hard but poorly documented limit on how large the compressed file could be, because of the very limited memory available during the boot process (the very reason that RLE was used in the first place - a plain BMP would have been 125kb and thus entirely too large; the default images are around 10 to 70kb each). If the file was too large, it would either simply fail to display or cause the system to crash, which required the user to reboot and drop into DOS mode before the logo had a chance to load, and either delete it or rename it to prevent the system trying to display it again before it could be fixed or replaced. Staying below, and moreover editing an image to bring it below this limit was an imprecise science that mostly required taking advantage of the particular characteristics of RLE, e.g. ensuring there were sufficient areas of the screen with long horizontal runs of the same color, by reducing the dither quality or color reduction mode, shrinking it slightly and adding a black border a few pixels wide all around, etc. Each run allowed a two byte code to represent a strip many pixels wide, and hence blank spaces or areas of flat color compressed very tightly, whereas regions with no repeated colors at all were at best uncompressed, at worst slightly larger than they would otherwise have been. References Replace the Ugly Startup and Shutdown Screens (archived version) External links MSKB (de): Individuelle Bilder bei Start und Beenden von Windows 98 anzeigen Windows components DOS files

Operating System (OS)

Clear Linux OS Clear Linux OS is a Linux distribution, developed and maintained on Intel's 01.org open-source platform, and optimized for Intel's microprocessors with an emphasis on performance and security. Its optimizations also affect AMD-systems. Clear Linux OS follows a rolling release model. Clear Linux OS is not intended to be a general-purpose Linux distribution; it is designed to be used by IT professionals for DevOps, AI application development, cloud computing, and containers. It currently is the fastest available Linux implementation. History In 2015, Intel introduced Clear Linux OS at OpenStack Summit 2015, Vancouver initially, it was limited to cloud usage. Intel began the Clear Containers project to address container security. In 2015, originally, Clear Linux OS was deployed as a single monolithic unit. In May 2019, Clear Linux OS released a new Desktop Installer and started a Help Forum. Clear Linux OS is available via Microsoft Azure marketplace, and Amazon Web Services marketplace. Requirements Clear Linux OS supports Sandy Bridge CPUs and later, including 2nd Generation Intel® Core™, Intel® Xeon® Processor E3, Intel® Atom™ processor C2000 (Q3 2013 or later), Intel® Atom™ processor E3800 (Q4 2013 or later). An installed system is booted via the EFI boot loader or via systemd-boot. A minimum system requires Intel SSE4 and CLMUL (carry-less multiplication), as well as UEFI. Features Clear Linux OS uses reference stacks to install images that are optimized and tested together for specific use-cases. It also utilizes a strict separation between User data and System config files, called stateless, so that even a misconfigured system will still boot correctly and then perform a factory reset so you can reconfigure. Desktop By default, Clear Linux OS ships with the GNOME desktop environment, but instead of Wayland it uses X11 by default and most graphical effects are disabled. KDE Plasma and Xfce are also available for installation. Package management Packages are usually installed and updated through bundles with the help of swupd, which is described as an OS-level software update program, using delta updates to minimize update size. Flatpak is also being preinstalled and can be used to install and use packages. Mixer is the tool for creating 3rd-party-bundles, which can then be installed using swupd. Competitors For containers: Fedora CoreOS RancherOS Snappy Ubuntu Core Mesosphere DC/OS VMware Project Photon OS Windows Nano Server SmartOS ResinOS openSUSE MicroOS Nano Server Bare Metal Container Name Clear Linux was referred to in early documentation as Clear Linux OS, later as Clear Linux* OS with a corresponding footnote acknowledging that the rights to "Linux" may be possessed by others. Clear Linux OS has been referred to, in the literature, as Clear Linux OS, Clear Linux* OS, Clear Linux OS, Clear Linux*, Clear Linux. References Further reading External links Enterprise Linux distributions X86-64 Linux distributions Linux distributions

Operating System (OS)

GEORGE (operating system) GEORGE was the name given to a series of operating systems released by International Computers and Tabulators (ICT) in the 1960s, for the ICT 1900 series of computers. These included GEORGE 1, GEORGE 2, GEORGE 3, and GEORGE 4. Initially the 1900 series machines, like the Ferranti-Packard 6000 on which they were based, ran a simple operating system known as Executive which allowed the system operator to load and run programs from a Teletype Model 33 ASR based system console. In December 1964 ICT set up an Operating Systems Branch to develop a new operating system for the 1906/7. The branch was initially staffed with people being released by the end of work on the OMP operating system for the Ferranti Orion. The initial design of the new system, named George after George E. Felton head of the Basic Programming Division, was based on ideas from the Orion and the spooling system of the Atlas computer. (In public it was claimed that George stood for GEneral ORGanisational Environment, but contemporary sources say that was a backronym). In July 1965 a team from ICT was present at a seminar at NPL describing the CTSS operating system developed for MIT's Project MAC. They decided that the ICT would need to provide multi-access facilities, known to ICT as MOP, "Multiple Online Processing". In November 1965 H. P. Goodman, head of the Operating Systems Branch attended the Fall Joint Computer Conference in Las Vegas where plans for Multics were initially described. Some of the Multics features discussed influenced future development of George, notably the tree structured filestore. Towards the end of 1965 ICT marketing requested that a simpler operating system be made available quickly, especially for the smaller members of the range. It was decided that two smaller systems, known as George 1 and George 2 be released rapidly, and the larger operating system was renamed George 3. GEORGE 1 & 2 George 1 was a simple batch processing system, Job descriptions were read from cards or paper tape which controlled the loading and running of programs, either loaded from cards or paper tape or magnetic tape. The job control language allowed definition of the peripherals and files to be used and handling of exception conditions. The job description would be checked for errors before the job was run. George used the trusted program facilities provided by executive to run the user programs. George 2 added the concept of off line peripheral handling (spooling). Several different modules, running in parallel, allowed overlapping of input, processing and output operations: Jobs were read from cards or paper tape to temporary files on magnetic disk or tape by an input module. A central module executed the user programs, taking input from the temporary input files and writing program output to temporary files. An output module wrote the temporary output files to physical printers and punches. A module was also available for entering jobs from remote job entry stations, the output of the job could be printed on the remote printer. If the installation was large enough multiple copies of the central module could be run, allowing multiple jobs to be processed in parallel. The George 2 job control language allowed use of stored macros with conditional facilities. George 2 provided no file system, the system and user programs relied on the facilities provided by executive. Files on disk were accessed by unique 12 character names and no security other than a "do not erase" bit was provided. MINIMOP could be run simultaneously with GEORGE 2 on the same machine, to provide on-line time-sharing facilities. Example George 2 batch job Here is a, somewhat artificial, example batch for George 2: The batch starts with a job description which specifies a job name, the account code used by George for billing and a user name: JOB PLAN4JOB,30174,BRIAN The job first loads the program #XPLT from a disk file named PROGRAM COMP (XPLT is the assembler). The document SOURCE is used as input to #XPLT on a virtual card reader CR0. IN ED(PROGRAM COMP) LOAD #XPLT IN CR0(SOURCE) ENTER 1 If #XPLT finishes with the message HALT OK then the job continues at label 1A, otherwise the job displays COMPILATION ERRORS and jumps to 5END. AT HALTED OK,GO TO 1A DISPLAY 'COMPILATION ERRORS' GO TO 5END At label 1A the program #XPCK is loaded and run with an in-line document available on its virtual card reader. (XPCK is the linker, or "consolidator" in ICL terminology). (The in-line document is the text between the line IN CR0/JD and the terminator ???*). 1A IN ED(PROGRAM COMP) LOAD #XPCK IN CR0/JD *IN ED(SEMICOMPILED) *OUT ED(PROGRAM TEST) *LIST ???* ENTER 1 AT DELETED HH,GO TO 2A DISPLAY 'CONSOLIDATION ERRORS' GO TO 5END If #XPCK finishes without error then the program #HWLD is run. 2A IN ED(PROGRAM TEST) LOAD #HWLD ENTER 0 5END END **** After the job a source document is read in, this will be used as input to the job. DOC SOURCE PROG(HWLD) STEER(LIST,OBJECT) OUTE(SEMICOMPILED(0)) WSF(HWLD) PLAN(CR) #PRO HWLD40/TEST #LOW MESS 12HHELLO WORLD #PRO #ENT 0 DISTY '11/MESS' DEL 2HOK #END ENDPROG **** Finally the end of batch is signaled. At this point all the jobs in the batch will be run in order. All output from the batch will be printed on the system printer. END BATCH In a real application the job would probably use a stored macro and be much simpler, this example has been written out longhand in an effort to show some of the features of the JCL. GEORGE 3 & 4 GEORGE 3 was the main version of the operating system series for the larger machines of the 1900 series. Initially it was released for the 1906/7; eventually it was made available for models down to the 1902T. In contrast to George 1 & 2 which ran as user-mode programs under executive, George 3 was a full operating system, leaving only low-level peripheral and interrupt handling to a cut-down version of executive. George 3 was implemented as a small memory-resident part and a collection of chapters (overlays) which were loaded into and removed from memory as needed. Chapters were strictly location-independent, allowing best use of memory. Internally George used cooperative multitasking; context switches could take place at any chapter change (call from one chapter to another), or at other specified places in the code. User-level code was run using preemptive multitasking; context switches were forced on I/O operations or clock ticks. George was written in a special assembler, GIN (George INput), which had richer conditional compilation and macro facilities than the standard PLAN assembler. Macros were heavily used by the code to reduce the effort of programming such a large system in assembly language. In later versions the macro features of GIN were used to add structured programming features to the code. Writing the system was estimated to have taken 75 programmer-years of effort. Job control George 3 was a mixed batch and online system. Jobs could be run from cards or tape in the same manner as George 2, or interactively from MOP (Multiple Online Processing) terminals, either simple Teletype Model 33 ASR terminals or block mode VDU terminals. The job control language was the same on terminals or in batch jobs and included conditional operations and macro operations. In contrast to Unix systems the job control language was part of the operating system rather than being a user level shell process. A job could only have one program loaded in to memory at a time, but one job could start other jobs to run concurrently, if system resources and site policy would permit. The system would swap user programs out of memory while they were waiting for input or output if other activities required memory to run. Filestore George 3 provided a tree structured Filestore, inspired in part by Multics. Every user of the system had a home directory with as many sub directories as needed under it. A users home directory could be accessed directly, for example the directory for user JOHN could be referred to as :JOHN, or by a full path, for example if JOHN was in the computer science department his home directory might be :MANAGER.USERS.COMPSCI.JOHN. Access control lists were used for security, a user could permit or deny any user or group of users access to his files or directories. File data storage was two-level: files could be either currently on disk, or, if the system was low on disk space they could be automatically relegated to magnetic tape. If an attempt was made to access a currently off line file the job would be suspended and the operators requested to load the appropriate tape. When the tape was made available the file would be brought back to disk and the job resumed. The underlying disc storage mechanism George 3, in 1968, was probably the earliest commercial version of a Copy-On-Write file system. The way this worked was that all modified blocks would be written to blocks on a "free" list. Blocks containing metadata were also treated in the same way but were, together with data blocks, physically written in an order in such a way that, when the final "master" block had been written, the file was committed. If the machine failed at any point, it was guaranteed by the hardware that the file would be in either its original, unmodified, form or fully up to date. Another useful feature was that the Filestore could emulate all the standard peripherals, such as card readers and punches, magnetic tapes and discs. This allowed older George 1 & 2 programs that required these physical devices, to be run under George 3 without modification. This could speed up jobs that required many tape or disc changes on George 1 & 2 to be automated to the extent - that something that required two operators; several 10s of tapes changes and five hours - now required no operators, further than mounting two work tapes for the results, and finished in 45 minutes. George 4 Starting with the 1904A, a paging unit was available for larger 1900 processors and George 4 was written to take advantage of it. George 4 remained compatible with George 3. It was common to alternate George 3 and 4 on the same machine and filestore, running George 3 during the day for small, interactive workloads and George 4 at night for large, memory intensive, jobs. George 4 introduced the concept of a sparse program, a program that had an addressing space larger than its allocated memory and read-only (pure) data and code regions. New versions of the consolidator (linker) and compilers were provided to use these facilities. The source code of George 3 and 4 were the same; conditional compilation facilities of the GIN assembler were used to select which version of the system was being compiled. As the 1900 paging feature was not emulated by the 2900 series machines used by later George installations, George 4 fell out of use before George 3. Examples Here are some simple examples of George use Example batch job The job is modelled on the George 2 job above, and like that job is somewhat artificial as in real use most of the work would be done by a pre-stored macro command. The job would be read in from a card or paper tape reader. With minor changes (removal of the first "JB" command) it could be stored in a file and run from an interactive (MOP) terminal. As with the George 2 example the job starts with a JOB command (all built-in commands had a long form and a two letter abbreviation, here "JB" is the abbreviation for "JOB"). The JOB command gives a job name, the user to bill for the job, :BRIAN, and the terminator for the job, "####". JB PLAN4JOB,:BRIAN,T#### WHENEVER (WE) a command fails with error the job will continue at label 5CE for error recovery. The MAXSIZE (MZ) of memory used by this job will be 20K words. WE COMERR,GO 5CE MZ 20K The CREATE (CE) command is used to make a file, in this case a temporary workfile, "!". The INPUT (IN) command then copies all text up to the terminator, "////" into the workfile. CE ! IN !,T//// PROG(HWLD) STEER(LIST,OBJECT) OUTE(SEMICOMPILED) WSF(HWLD) PLAN(CR) #PRO HWLD40/TEST #LOW MESS 12HHELLO WORLD #PRO #ENT 0 DISTY '11/MESS' DEL 2HOK #END ENDPROG //// The LOAD (LO) command loads PROGRAM XPLT (the assembler) from the directory :LIB, it is then started by the RESUME (RM) command. If the run does not HALT with the output LD the job continues at label 1F for error handling. LO :LIB.PROGRAM XPLT RM IF NOT HAL(LD),GO 1F The ASSIGN (AS) command is used to connect virtual card reader unit 0 to the workfile created above, which is then erased by the ERASE (ER) command. (The erase will be delayed until the file is closed). AS *CR0,! ER ! A new workfile is created and the virtual line printer unit 0 assigned to it. CE ! AS *LP0,! When PROGRAM XPLT is run it will try to open the disk file in the OUTE directive, We want it to use a temporary workfile so we ask George to MONITOR the open, stopping execution and allowing us to provide the workfile: MN ON, OPEN The program in memory (PROGRAM XPLT) is started at location 21. EN 1 IF NOT MONITOR(OPEN), GO 1F A new, direct access, workfile is created with 128 word buckets and an initial size of 40K words. The virtual disk channel *DA2 is assigned to it. The program is RESUMED. CE !(*DA,BUCK1,KWOR40) AS *DA2,!(WRITE) RM If it HALTs with the output OK the job continues at label 1A, if not an error message is displayed and the job exits. IF HAL(OK),GO 1A 1F DP 0,COMPILATION ERRORS GO 5EX The DELETE (DL) command deletes the assembler from memory. 1A DL Yet another workfile is created to hold the instructions for the linker. As the linker instructions must end with a line "****" the default terminator is used for the INPUT command. CE ! IN ! *IN ED(SEMICOMPILED) *OUT ED(PROGRAM TEST) *LIST **** The linker, :LIB.PROGRAM XPCK is loaded and initialised. LO :LIB.PROGRAM XPCK RM IF NOT HAL(LD),GO 2F The virtual card reader is attached to the workfile holding the linker instructions, which is then erased. AS *CR0,! ER ! The virtual lineprinter is then assigned in append mode to the last but one workfile created and not yet erased (workfiles are held in a stack, "!" is the top of the stack, "!1" the one under that and so on). The LISTFILE (LF) command is used to print the file on the system printer (the listing will start when the file is closed). The file is then erased (the erase will be delayed until the listing is finished). The virtual disk channel *DA1 is assigned to the top workfile (holding the assembler output) and yet another workfile is created for the linker. AS *LP0,!1(APPEND) LF !1,*LP,PA ER !1 AS *DA1,! ER ! CE !(*DA,BUCK1,KWOR10) AS *DA13,!(WRITE) ER ! A file is created to hold the linker output and attached to virtual disk channel *DA14. The linker is then started at location 21 and if it finishes with the message HH the job continues at label 2A, otherwise an error message is displayed and the job exits. CE PROGRAM HWLD(*DA,BUCK1,KWOR5) AS *DA14,PROGRAM HWLD(WRITE) EN 1 IF DEL(HH),GO 2A 2F DP 0,CONSOLIDATION ERRORS GO 5EX At label 2A the program written by the linker is loaded into memory and run starting at location 20, a success message is displayed and the job exits. 2A LO PROGRAM HWLD EN 0 DP 0,JOB COMPLETED GO 5EX If any command failed the WHENEVER command given at the start of the job will force a jump to label 5CE which displays an error message and exits. 5CE DP 0,COMMAND ERROR IN JOB When the job gets to label 5EX if it has a currently loaded program it is deleted from memory and the ENDJOB (EJ) command terminates the job. 5EX IF COR,DL EJ ALL The end of the job is signalled by the terminator string defined by the JOB command. #### Example MOP session All user input is shown in lower case. All output from George is in upper case. The user types control-A on an idle Teletype attached to George, George replies with its identification banner and prompt (the time, followed by the invitation to type, a back-arrow. The user then logs in using the LOGIN (LN) command. He is prompted for his password, which will be echoed as the terminal is connected in half duplex mode with local echo. The job then starts. THIS IS GEORGE 3 MARK 8.67 ON 21MAR11 21.21.23← ln :john,mopjob TYPE PASSWORD← password STARTED :JOHN,MOPJOB,21MAR11, 21.21.35 TYPE:MOP A directory is created with the MAKEDIR (MK) command and the current directory is changed to the new one with the DIRECTORY (DY) command. 21.21.35← mk hellodir 21.28.10← dy hellodirThe system macro NEWCOPYIN is used to read from the tape serial number 123457. As the NEWCOPYIN macro loads a program the session becomes fully started (if the system was heavily loaded it might wait at this point). 21.28.16← newcopyin (123457) 21.28.32 JOB IS NOW FULLY STARTED 21.28.32 0.03 CORE GIVEN 4736 WAITING FOR MT 123457 Apparently the system operator couldn't find the tape and used the CANTDO command to refuse to load it, the NEWCOPYIN fails. ERROR IN PARAMETER 2 IN OL IN NEWCOPYIN: MT (123457) CORRECTLY IDENTIFI ED BUT NOT AVAILABLE DISPLAY: ERROR IN NEWCOPYIN . MACRO ABANDONED 21.28.58 FREE *CR0, 0 TRANSFERS 21.28.58 0.05 DELETED,CLOCKED 0.00 0.05 :DELETED END OF MACRO The user tries again with the correct serial number this time. When the tape becomes available he is prompted for the file to load. The list of files is terminated by "****". 21.28.58← newcopyin (123456) 21.32.21 0.06 CORE GIVEN 4736 WAITING FOR MT 123456 21.32.34 USED U31 AS *MT0, MT (123456,HELLOTAPE(0/0)) ← hello,hello(/plan) ← **** 21.32.52 FREE *CR0, 2 TRANSFERS DISPLAY : 1 PARAMETER ACCEPTED DISPLAY 0.08: MONITOR DISPLAY : INPUT TAPE * 123456. DISPLAY 0.08: MONITOR 21.32.52 FREE *FH0, 1 TRANSFERS 21.32.52 FREE U31,8 TRANSFERS 0.10 :DELETED : OK 21.32.52 0.10 DELETED,CLOCKED 0.00 END OF MACRO The file has been loaded from tape. The LISTFILE (LF) command is used to examine its contents 21.32.52← lf hello #PRO HWLD40/TEST #LOW MESS 12HHELLO WRLD #PRO #ENT 0 DISTY '11/MESS' DEL 2HOK #END There seems to be an error, so the user uses the EDIT (ED) command to fix it. The editor subcommand TC is used to position to the line containing "WRLD", the R command replaces "WRLD" by "WORLD", then the E command writes out the file. 21.33.01← ed hello EDITOR IS READY 0.0← tc/wrld/ 2.0← r/wrld/world/ 2.29← eThe system macro PLANCOMP is used to compile the file HELLO(/PLAN) to PROGRAM HELO 21.43.46← plancomp *cr hello(/plan),*idhelo FILES ALREADY ONLINE: :LIB.SUBGROUPS-RS(1/V3) :LIB.PROGRAM XPCK(1/V12K) :LIB.PROGRAM XPLT(1/V8C) 21.43.58 0.58 CORE GIVEN 18944 0.58 :HALTED : LD DISPLAY : START JOB HELO, OPEN *DA2 N CA 1641 M=#00100 FN=SEMICOMPILED 1.00: MONITOR 21.43.58 FREE *CR0, 8 TRANSFERS DISPLAY : COMP OK 84 #HELO 21.43.58 FREE *DA2, 9 TRANSFERS 1.01 :DELETED : FI #XPCK 21.43.58 FREE *TR0, 7 TRANSFERS 21.43.58 FREE *LP0, 83 TRANSFERS 21.43.58 1.01 DELETED,CLOCKED 0.00 21.43.59 1.07 CORE GIVEN 11392 21.43.59 FREE *CR0, 5 TRANSFERS 21.43.59 FREE *DA14,20 TRANSFERS 21.43.59 FREE *DA1, 9 TRANSFERS 21.43.59 FREE *DA2, 2 TRANSFERS 21.43.59 FREE *DA13,7 TRANSFERS 1.07 :DELETED : HH 21.43.59 FREE *LP0, 32 TRANSFERS 21.43.59 FREE *DA15,0 TRANSFERS 21.43.59 1.07 DELETED,CLOCKED 0.00 DISPLAY: PLAN COMPILATION/CONSOLIDATION OKAY END OF MACRO The newly compiled PROGRAM HELO is loaded into memory by the LOAD (LD) command, then started with the ENTER (EN) command. It displays the traditional message then deletes itself from memory. 21.43.59← lo program helo 21.44.06← en 21.44.07 1.09 CORE GIVEN 64 DISPLAY : HELLO WORLD 1.09 :DELETED : OK 21.44.07 1.09 DELETED,CLOCKED 0.00 Today's arduous work being finished, the user logs out with the LOGOUT (LT) command. The mill time and money used and remaining are displayed. 21.44.07← lt MAXIMUM ONLINE BS USED 252 KWORDS 21.44.12 1.09 FINISHED : 0 LISTFILES BUDGET USED LEFT TIME(M) 70 -97797 MONEY 35 80327 21.44.12← Source code George was distributed in a form that allowed a site to modify large parts of the system. A compilation of the system was started, then interrupted just before the end and dumped to magnetic tape. The GIN compiler allowed the compilation to be continued from this point at the user site, possibly modifying code already compiled. Versions of George 3 before release 8 were provided in binary form. Any modifications needed to the system were made as binary patches. To simplify the process most George chapters included an empty MEND area at the end. Starting with release 8 the source of George was distributed with the binary, both on magnetic tape and microfiche. A system of source level patches, known as MENDITS'' was used to modify the system and an existing chapter could be completely replaced by the new modified chapter. The George user group set up a "MEND exchange scheme" to share interesting modifications to George. Some modifications were distributed freely, others were available for a fee. When ICL produced a new version of George they would sometimes include modifications produced by the users. For the last released version, 8.67, most of the patches from the MEND exchange scheme were included in the standard George source, switched off by conditional compilation. They can be turned on as part of the standard process of tailoring George for a site. Documentation GEOrge was well documented internally in a series of looseleaf folders, distributed as an initial version plus amendments. Eventually all the original pages were replaced, so any new copy of the manuals consisted of a box of empty looseleaf folders and a pile of amendments. The first amendment was a list of contributors, and the technical reason for the amendment was described as "to keep everyone happy". Modified Versions A modified version of George 3 was supplied to the University of Manchester Regional Computer Centre (UMRCC). This linked George 3 to a CDC Cyber machine, to which George supplied the offline I/O and Job queueing functions. Online support was supplied by both ICL and Cyber for both hardware and software. The Cyber support team worked in an office with the name "Cybermen" on the door. End of life Obsolescence With the release of ICL's "new range", the 2900 series with its VME operating system, George became obsolete. However, due to the legacy of investment in software for George, ICL released options to run 1900 series software, including George, on 2900 series machines, initially the Direct Machine Environment (DME), later the Concurrent Machine Environment (CME) which allowed simultaneous running of 1900 and 2900 code on the same system. New versions of George 3 continued to be released for the 2900. The last version was 8.67, released in 1983. As of 2005 at least one site in Russia was still running George 3 under DME. In November 2014 George 3 was run on a reconditioned ICL 2966 at the National Museum of Computing. Emulation David Holdsworth and Delwyn Holroyd obtained copies of George 3 issue tapes when the last live site in the UK, at British Steel Corporation, was being decommissioned and wrote an emulator for the 1900 hardware and executive that allows running of George on Microsoft Windows and Linux as part of a project for the Computer Conservation Society. The emulator includes an emulation of Executive and a Java emulation of an ICL7903 Communications Processor making it possible to run MOP sessions by telnetting to (in this case) port 2023. George 3 Executive Emulator by David Holdsworth & Delwyn Holroyd Build: May 15 2014 Memory size: 256K Exec command: DA GEORGE3A Waiting for a console telnet connection on port 1900 ICL 7903 Communications Controller emulator by David Holdsworth & Delwyn Holroyd Build: Feb 23 2014 -? for usage info Listening for TTY connections on port 2023 - 4 available Listening for VDU connections on port 7181 - 4 available Listening for host connection on port 7903 Tests with the emulator show that George 3 is Y2K compliant. References Further reading ICL operating systems Multics-like

Operating System (OS)

System76 System76 is an American computer manufacturer based in Denver, Colorado, specializing in the sale of notebooks, desktops, and servers. The company supports and has always supported free and open-source software, and offers either Ubuntu or their own Ubuntu-based Linux distribution Pop!_OS as the preinstalled operating system. History System76 was founded by Carl Richell and Erik Fetzer. In 2003, Fetzer registered the domain system76.com to sell computers with the Linux operating system preinstalled. The idea was not pursued until two years later. In mid-2005, Richell and Fetzer's most important and challenging question in the early stages of the company was that of which Linux distribution to use. Their quest to bring Linux to the mass market required choosing the best distribution for their customers. Red Hat Enterprise Linux, openSUSE, Yoper and other distributions were considered and dismissed. Ubuntu was initially dismissed, but Richell and Fetzer changed their mind quickly after giving it a more thorough evaluation. Furthermore, Richell was particularly fond of Canonical’s business model: completely free software, which was backed by commercial support as necessary. The first computers sold by System76 shipped with Ubuntu 5.10 Breezy Badger preinstalled. In response to Canonical Ltd. switching to GNOME for future releases of Ubuntu, System76 announced in May 2017 a new shell theme called Pop. To further their efforts in making Ubuntu fit more with System76's vision, the company announced in June 2017 that it would be creating its own Linux distribution based on Ubuntu called Pop!_OS. Company name The number 76 in the company name alludes to the year 1776, when the American Revolution took place. The company founders likewise hope to ignite an open source revolution, ultimately leading to a situation in which consumers do not rely primarily on proprietary software. Products System76's products are typically named after the fauna of Africa. Laptops Lemur Lemur Pro Gazelle Kudu Pro Galago Pro Oryx Pro Bonobo WS Serval WS Darter Pro Pangolin Desktops Meerkat Thelio Thelio Major Thelio Massive Thelio Mega Past systems Wild Dog Pro Leopard WS Silverback WS Servers The servers sold by System76 were some of the first servers to offer the Ubuntu Linux distribution pre-installed. Recent models, as of 2012, have garnered generally positive reviews, which cite value and hardware compatibility as primary advantages. Jackal 1U Jackal Pro 1U Jackal Pro 2U Ibex Pro GPU Starling Pro ARM Pop!_OS Pop!_OS is a Linux distribution developed by System76, based on Ubuntu by Canonical Ltd. and using the GNOME Desktop Environment. It is intended for use by "developers, makers, and computer science professionals". Pop!_OS provides full disk encryption by default as well as streamlined window management, workspaces, and keyboard shortcuts for navigation. Community relations The company has a history of sponsoring the Ubuntu Developer Summit, Southern California Linux Expo, and other Open Source/Linux events and conferences. Their official support forums are hosted by Canonical Ltd., the primary developer of Ubuntu. System76 is an active member in the Colorado Ubuntu Community, serving as the corporate sponsor for Ubuntu LoCo events and release parties in downtown Denver. See also Framework Computer Linux adoption Purism (company) Pine64 References External links Companies based in Denver Computer companies of the United States Computer hardware companies Consumer electronics brands Online retailers of the United States Ubuntu

Operating System (OS)

BS2000 BS2000 is a mainframe computer operating system developed in the 1970s by Siemens (Data Processing Department EDV) and from early 2000s onward by Fujitsu Technology Solutions. Unlike other mainframe systems, BS2000 provides exactly the same user and programming interface in all operating modes (batch, interactive and online transaction processing) and regardless of whether it is running natively or as a guest system in a virtual machine. This uniformity of the user interface and the entire BS2000 software configuration makes administration and automation particularly easy. Currently, it is mainly used in Germany - making up to 83% of its total user base - as well as in the United Kingdom (8%), Belgium (4,8%) and other European countries (4,2%). History BS2000 has its roots in the Time Sharing Operating System (TSOS) first developed by RCA for the /46 model of the Spectra/70 series, a computer family of the late 1960s related in its architecture to IBM's /360 series. It was an early operating system which used virtual addressing and a segregated address space for the programs of different users. From the outset TSOS also allowed data peripherals to be accessed only via record- or block-oriented file interfaces, thereby preventing the necessity to implement device dependencies in user programs. The same operating system was also sold to Sperry Univac when it bought most of RCA's computer division. Univac's "fork" of TSOS would become VS/9, which used many of the same concepts. 1970s In 1973, BS2000 V1.0 was a port of the TSOS operating system to models of the Siemens system 7.700 In June 1975, Siemens shipped the enhanced BS2000 V2.0 version of the TSOS operating system for the models of the Siemens 7.700 mainframe series for the first time under the name BS2000. This first version supported disk paging and three different operating modes in the same system: interactive dialog, batch, and transaction mode, a precursor of online transaction processing. In 1977, the TRANSDATA communication system used computer networking. In 1978, multiprocessor technology was introduced. The operating system had the ability to cope with a processor failure. At the same time the new technology considerably extended the performance range of the system. In 1979, a transaction processing monitor, the Universal Transaction Monitor (UTM), was introduced, providing support for online transaction processing as an additional operating mode. 1980s In 1980, Siemens introduced the system 7.500 hardware family, ranging from desk size models for use in office environments to large models with water cooling. In 1987, BS2000 V9.0 was ported to the /370 architecture supported 2GB address spaces, 512 processes and the XS channel system (Dynamic Channel Subsystem). BS2000 was subdivided into subsystems decoupled from one another. 1990s With the advent of the VM2000 virtual machine in 1990, multiple BS2000 systems, of the same or different versions, can run in parallel on the same computer. The hierarchical storage management system (HSMS) swapped out infrequently used data to cheaper storage media. When the data is needed again, it is restored to high-speed access media. The ROBAR tape archiving system supported robot systems. In 1991, the Security evaluation to F2/Q3 was completed. From 1992 through 1995, BS2000/OSD V1.0 was made open to application software and was renamed BS2000/OSD (Open Server Dimension). Full support of the XPG4 standard was achieved in 1995 after the porting of the POSIX interfaces in 1992. In 1996, BS2000/OSD was ported to the MIPS architecture. Although the operating system ran on different hardware architectures (S servers with /390 architecture and SR2000 servers for the MIPS architecture), applications produced for /390 can be used on computers based on MIPS architecture without recompilation due an emulation layer for legacy code. In 1997, WebTransactions allowed applications to use the Internet. In 1999, BS2000/OSD was the first operating system to be awarded Internet Branding by The Open Group. 2000s In 2002, BS2000/OSD was ported to the SPARC architecture, leading to the Fujitsu Siemens Computers' SX server line. In 2004, support for storage area networks based on Fibre Channel technology was introduced. In 2006, BS2000/OSD V7.0 introduced support for new server generations, Unicode support, and improved SAN integration. In 2008, BS2000/OSD was ported to the x86 architecture, and the SQ server line was introduced. 2010s In 2012, BS2000/OSD version 9.0 was released. Pilot release of version 10.0 started in November 2014, and it was released in May 2015. Pilot release of version 11.0 started in March 2017, and it was released in July 2017. See also Timeline of operating systems VS/9 References External links BS2000 Mainframes BS2000 Operating System BS2000 Documentation BS2000 Germany 1975 software Proprietary operating systems Mainframe computers MIPS operating systems

Operating System (OS)

Language-based system A language-based system is a type of operating system that uses language features to provide security, instead of or in addition to hardware mechanisms. In such systems, code referred to as the trusted base is responsible for approving programs for execution, assuring they cannot perform operations detrimental to the system's stability without first being detected and dealt with. A very common strategy of guaranteeing that such operations are impossible is to base the system around a high-level language, such as Java, whose design precludes dangerous constructs; many are entirely written in such a language, with only the minimum amount of low-level code being used. Since language-based systems can assure ahead of time that they cannot do things that can damage the system (such as corrupting memory by dereferencing dangling pointers), it is possible for them to avoid expensive address space switches needed by traditional OSes; because of this, microkernels are more popular than traditional systems. A more extreme form of this is a high-level language computer architecture, where the trusted base is pushed into hardware, and the entire system is written in a high-level language. Examples Burroughs MCP Cosmos Emerald Inferno JX Lisp machine Midori Oberon Singularity Smalltalk UCSD P-system Verve See also High-level language computer architecture References A Sabelfeld, AC Myers Language-based information-flow security IEEE Journal on Selected Areas in Communications, 2003 Volume 21, Issue 1 pp. 5–19 V Haldar, D Chandra, M Franz Semantic remote attestation—a virtual machine directed approach to trusted computing USENIX Virtual Machine Research and Technology Symposium, 2004 Giacobazzi, Mastroeni Abstract non-interference: parameterizing non-interference by abstract interpretation Proceedings of the 31st ACM SIGPLAN-SIGACT symposium on Principles of programming languages pp 186–97 (2004) Algis Rudys, Dan S. Wallach Termination in language-based systems ACM Transactions on Information and System Security (TISSEC) Volume 5, Issue 2 (May 2002) pp. 138–68 Operating system kernels

Operating System (OS)

Windows X Windows X may refer to: X Window System, a windowing system for bitmap displays, common on UNIX-like computers An implementation of the X server for Microsoft Windows; see Windows 10, a Microsoft operating system See also Windows key Windows XP Windows 9x List of Microsoft Windows versions Windows (disambiguation)

Operating System (OS)

Mac OS X Public Beta The Mac OS X Public Beta (internally code named "Kodiak") was the first publicly available version of Apple Computer's Mac OS X (now named macOS) operating system to feature the Aqua user interface. It was released to the public on September 13, 2000 for US$29.95. Its release was significant as the first publicly available evidence of Apple's ability to ship the long-awaited "next-generation Mac operating system" after the Copland failure. It allowed software developers and early adopters to test a preview of the upcoming operating system and develop software for the forthcoming operating system before its final release. It is the only public version of Mac OS X to have a code name not based on a big cat until the release of 10.9 Mavericks in 2013. The US version had a build number of 1H39 and the international version had build number 2E14. Successor OS The Public Beta succeeded Mac OS X Server 1.0, the first public release of Apple's new NeXT OPENSTEP-based operating system, which used a variant of the classic Mac OS's "Platinum" user interface look and feel. The Public Beta introduced the Aqua user interface to the world. Fundamental user interface changes were revealed with respect to fonts, the Dock, the menu bar (with an Apple logo at the center that was later repositioned to the left of the menu bar and made an active interface element). System icons were much larger and more detailed, and new interface eye candy was prevalent. Technical changes The beta's arrival marked some fundamental technical changes, most courtesy of an open source Darwin 1.2.1 core, including two features that Mac users and developers had been anticipating for almost a decade: preemptive multitasking and protected memory. To illustrate the benefits of the latter, at the MacWorld Expo in June 2000, Apple CEO Steve Jobs demonstrated Bomb.app, a test application intended to crash. Native software The Public Beta included many of the standard programs bundled with macOS for decades to come, such as TextEdit, Preview, Mail, QuickTime Player and Terminal. Also included with the Public Beta, but not in any subsequent versions of Mac OS X, were a simple MP3 player (iTunes had not yet been introduced), Sketch, a basic vector drawing program demonstrating features of Quartz, and HTMLEdit, a WYSIWYG HTML editor inherited from WebObjects. Native shrinkware applications were few and far between. Early adopters had to turn to open source or shareware alternatives, giving rise to an active homebrew software community around the new operating system. Many programs in use on early Mac OS X systems were inherited from OPENSTEP or Rhapsody developer releases (e.g. OmniWeb or Fire), or were simple wrapper apps that provided a graphical interface to a command-line Unix program. The poor state of the Carbon API contrasted with the relative maturity of Cocoa gave rise to an anti-Carbon bias among Mac OS X users. Expiration The Mac OS X Public Beta was expired on May 14, 2001; approximately two months after the release of Mac OS X 10.0, the completed version of the operating system released in March 2001. As a result, it will not run on later PowerPC-based Macintosh computers released after early 2001, nor on current Macintosh hardware, which uses the x86 or ARM64 processor architectures. Using the Mac OS X Public Beta on compatible equipment today requires setting the hardware clock to a date prior to the expiration date. The expiration date forced users to purchase a copy of the final release rather than continuing to use the Public Beta, as well as reassured industry observers skeptical after the Copland and Rhapsody failures that Apple would actually release a next-generation operating system this time. Owners of the Public Beta version were entitled to a $30 discount on the price of the first full version of Mac OS X 10.0. Only the Aqua GUI and related components of the Public Beta were subject to expiry; the underlying Darwin command-line based OS continued to function. References 2000 software MacOS PowerPC operating systems

Operating System (OS)

Option ROM An Option ROM for the PC platform (i.e. the IBM PC and derived successor computer systems) is a piece of firmware that resides in ROM on an expansion card (or stored along with the main system BIOS), which gets executed to initialize the device and (optionally) add support for the device to the BIOS. In its usual use, it is essentially a driver that interfaces between the BIOS API and hardware. Technically, an option ROM is firmware is executed by the BIOS after POST (the testing and initialization of basic system hardware) and before the BIOS boot process, gaining complete control of the system and generally unrestricted in what it can do. The BIOS relies on each option ROM to return control to the BIOS so that it can either call the next option ROM or commence the boot process. For this reason, it is possible (but not usual) for an option ROM to keep control and preempt the BIOS boot process. The BIOS (at least as originally designed by IBM) generally scans for and initializes (by executing) option ROMs in ascending address order at 2 KB address intervals within two different address ranges above address C0000h in the conventional (20-bit) memory address space; later systems may also scan additional address ranges in the 24-bit or 32-bit extended address space. Option ROMs are necessary to enable non-Plug and Play peripheral devices to boot and to extend the BIOS to provide support for any non-Plug and Play peripheral device in the same way that standard and motherboard-integrated peripherals are supported. Option ROMs are also used to extend the BIOS or to add other firmware services to the BIOS. In principle, an option ROM could provide any sort of firmware extension, such as a library of video graphics subroutines, or a set of PCM audio processing services, and cause it to be installed into the system RAM and optionally the CPU interrupt system before boot time. A common option ROM is the video BIOS which gets loaded very early on in the boot process and hooks INT 10h so that output from the power-on self-test (POST) can be displayed. The video BIOS is almost always located in the 32 kB memory segment beginning at C0000h, the start of the memory area reserved for option ROMs; this is because when the motherboard has a built-in VGA controller, the option ROM will reside in the BIOS – the BIOS knows where it is and shadows it into RAM at a fixed time. Other ROMs can be located from segments C8000h all the way up to F4000h in early PCs. The final search address was limited to segment DFFFFh in later products and eventually to EFFFFh in modern products. The BIOS Boot Specification requires that option ROMs be aligned to 2 kB boundaries (e.g. segments C8000h, C8800h, C9000h, C9800h, etc.). The first two bytes of the ROM must be 55 AA.The third byte indicates the ROM size, and the fourth byte is where the BIOS begins execution of the option ROM to initialize it before the system boots. Original usage of Option ROMs for booting through expansion cards Prior to the development and ubiquitous adoption of the Plug and Play BIOS standard, an add-on device such as a hard disk controller or a network adapter card (NIC) was generally required to include an option ROM in order to be bootable, as the motherboard BIOS did not include any support for the device and so could not incorporate it into the BIOS's boot protocol. Such an option ROM would hook INT 19h, the BIOS boot interrupt, to preempt the BIOS boot loader and substitute their own boot loader. The boot loader on the option ROM would attempt to boot from a disk, network, or other boot program source attached to or installed on the adapter card; if that boot attempt failed, it would pass control to the previous boot loader (to which INT 19h pointed before the option ROM hooked it), allowing the system to boot from another device as a fallback strategy. Some adapters cards, such as certain SCSI adapters (e.g. some made by Adaptec), were available in versions that differed only in the presence or absence of the option ROM to enable booting from attached SCSI devices. As a result of the option ROM scanning protocol, the highest-addressed option ROM is the last one to be initialized and so the last one to hook any interrupts and the first one in those interrupt service routine (ISR) chains; thus the addresses of the option ROMs completely determine the boot priority between adapter cards that are enabled for booting, and the boot devices supported by the motherboard BIOS collectively have lowest priority, i.e. the system will attempt to boot from them only after attempting to boot from all boot-enabled adapter cards. BIOS Boot Specification The BIOS Boot Specification (BBS) was developed by a consortium comprising Compaq, Intel and Phoenix Technologies to standardize the initialization sequence of Plug and Play (PnP) BIOS option ROMs, and legacy option ROMs not conforming to the PnP BIOS standard, and the order in which they hook interrupts. The standard presents the notion of a Boot Connection Vector (BCV) table and BCV priority. The core principles of the standard make behaviour more defined and debuggable and gives BIOS manufacturers room to further dynamise boot device selection for the user, beyond the suggestions of the standard. After the basic POST checks are complete, the BBS specifies that the BIOS will detect and shadow all option ROMs that reside in the BIOS into the aforementioned region and it will traverse the PCI configuration space, filling in XROMBARs and copying the expansion card option ROMs from MMIO space to the region. The BIOS then scans the region, and if the option ROM has a PnP Expansion header, it does a far call to offset +03h in the option ROM header to initialize it. It then rescans the region after all the PnP option ROMs have been initialized (because, as appendix E states, the option ROM initialization routine may have chained more PnP expansion headers for individual disks the device owns). It adds the BCV pointer (if present) in the PnP Expansion headers it finds the BCV Table or the BEV pointer (if present) to the IPL priority table. The BCV entries in the BCV table are then called according to priority settable in NVRAM. The BCV table is full of BCV function pointers but has a fixed entry representing legacy option ROMs which is a pointer to a BIOS routine which calls +03h in all the remaining option ROMs that don't have a PnP Expansion header. The BCV function initializes the INT 13h and INT 19h hooks, which the BBS stipulates must not be done in the initialization routine at +03h. If a device has no PnP Expansion header, it may perform any hook in the routine at +03h, as it is a legacy card. In the initial initialization routine, as the Option ROM points to a PCI data structure (not the same as the configuration space), the option ROM code knows the device and vendor ID is at a fixed offset from RIP. This allows it to scan the PCI configuration space to find the correct device and BARs it needs to use. To prevent this scan, and in case of two identical cards in the system, the BIOS passes the PFA (bus/device/function) to the initialization routine in AX, and the card select number (CSN) for ISA option ROMs is passed in BX. It can then interact with the device using PMIO / MMIO to see how many disks it has and which ones are bootable by reading the MBR. The BIOS will have already combed the configuration space, allocated the BARs and filled in the ACPI table prior to the initialization routine call, so the option ROM would use the addresses allocated to its BARs. The BCV, however, hooks interrupt routines which interact with the device which are adjusted based on a base MMIO address location, disk information ascertained in the option ROM initialization routine and the current disk number in the BDA. The BIOS INT 19h procedure then uses the IPL table priority in NVRAM to decide whether to call an entry containing a boot handler which will read the MBR of 00h (floppy disk BAID; the first device in the BCV table to register disk 00h), an entry containing a boot handler which will read the MBR of 80h (the hard drive BAID; the first device in the BCV Table to register disk 80h) or one of the BEV entries in the table. A device only has a BEV or a BCV if it is a bootable device. SCSI A SCSI controller card may hook INT 13h which is responsible for providing disk services. It will do so in its BCV if it is a PnP card. Once it has done this, any subsequent calls to INT 13h will be "caught" by the SCSI option ROM (or "SCSI BIOS"), allowing it to respond for disks that may exist on the SCSI bus. Before it had hooked the interrupt there may have been no disks on the system, but by intercepting the interrupt and altering the values returned, the SCSI BIOS can make all the disks on the SCSI bus visible to the system. In this particular case, the BIOS itself may call INT 13h to provide a list of possible boot devices to the user, and because the SCSI BIOS has hooked the interrupt the user will be able to choose not only which standard system devices to boot from, but also which SCSI disks as well. This is because, as suggested in Appendix D of the Boot BIOS Specification, the BIOS could populate the IPL table with device and vendor information from INT 13h calls to the different disks, paired with the Hard Disk Number (80h, 81h ...), to allow any hard disk device to be booted from, rather than just the first disk of the first controller to hook INT 13h (the highest priority item in the BCV table), referred to as a BIOS Aware IPL Device (BAID) in the specification. Multiple controllers can hook INT 13h at once. For instance, after the SCSI controller, an AHCI controller can also hook INT 13h by putting a call to the previous handler, which was stored in the IDT at entry 13h by the SCSI controller, at the end of its own handler, before it puts the address of its own handler into the IDT at entry 13h. The first controller to hook INT 13h will see that 0 disks have been installed by checking the byte at 0040:0075, which resides in the BIOS Data Area (BDA), and if it has 4 disks to enumerate, it will assign the range of disk numbers 80h–83h and store '4' in the BDA. If the second controller to hook INT 13h has 2 disks, it will read '4' from the BDA, assign the disk numbers 84h and 85h, and store '6' in place of the '4'. Now if INT 13h is called with DL = 83h, then the handler of the second controller, which did not assign disk number 83h, will relay the call to the previous handler; that handler, which did assign disk number 83h, will handle the call itself. With any number of controllers' ISRs hooked into INT 13h, the ISRs will each pass control to the next one until the one that assigned the specified drive number recognizes the number, handles the call, and returns from the interrupt. Network boot ROM Another common option ROM is a network boot ROM. The option ROM contains the program required to download the boot code. The original IBM Personal Computer ROMs hooked INT 18H (originally to invoke Cassette BASIC) and INT 19H, as these two interrupts were used for the boot process. INT 19h is called to initiate the boot process, and INT 18h was called to start Cassette BASIC from ROM when the boot process found that none of the possible boot devices was bootable. Originally, by hooking INT 18h, the network adapter ROM would try to boot from the network when all other boot devices (floppy drives, hard drives, etc.) had failed. By hooking INT 19H, the network adapter ROM would attempt to boot from the network before any other devices. The BBS specifies that the NIC option ROM does not hook INT 19h, but instead the BIOS 19h handler should call the BEV, which will then download the boot code. Video The Video BIOS provides some basic display services for BIOS and operating systems, for example INT 10H (Legacy BIOS), VBE (Legacy BIOS) and UEFI GOP. The original IBM PC BIOS included integrated support for the IBM CGA and MDA video adapters (and did not support option ROMs at all), so those video cards had no option ROMs. The CGA and MDA support in the BIOS proper was maintained through the IBM PC XT and PC AT product lines (which did support option ROMs), so that those cards worked (with full BIOS support) in those machines. The first PC video adapter card that had an option ROM was the IBM EGA, introduced in 1984 with the IBM PC AT. (The Hercules Graphics Card had no option ROM and no BIOS support except for its MDA-compatible features, for which it relied in the IBM-supplied MDA support in the main BIOS.) Most subsequent PC video adapters were supported by option ROMs, although VGA and MCGA integrated onto PS/2 motherboards may have used integrated BIOS support. Once integrated Super VGAs (SVGAs), integrated on clone PC motherboards, were being provided by separate companies than the systems themselves, it became common for the SVGA vendor-provided video BIOS to be included as a separate option ROM module on the same BIOS chip as the main system BIOS (provided by a third separate company). UEFI Option ROMs The PCI spec allows multiple option ROM images on the same device. These option ROMs could be Legacy x86 & UEFI. If the Option ROM format is set to "UEFI Compatible" in the UEFI Setup, the DXE stage will load the newer UEFI Option ROM if one is present and the legacy Option ROM if one is not. UEFI can use legacy option ROMs when a Compatibility Support Module (CSM) is enabled. Note that when Secure Boot is enabled, execution of the Compatibility Support Module and legacy option ROMs is prohibited because legacy firmware drivers do not support authentication, which is a security hole. See also BIOS UEFI Booting Legacy Plug and Play PCI configuration space Read-only memory (ROM) Preboot eXecution Environment (PXE) References BIOS

Operating System (OS)

Windows 8 Windows 8 is a major release of the Windows NT operating system developed by Microsoft. The product was released to manufacturing on August 1, 2012, and generally to retail on October 26, 2012. Windows 8 was made available for download via MSDN and TechNet. Windows 8 is the first version of Windows to support the ARM architecture, under the Windows RT branding. Microsoft released Windows 8.1 in October 2013, addressing some aspects of Windows 8 that were criticized by reviewers and early adopters and incorporated additional improvements to various aspects of the operating system. Windows 8 was ultimately succeeded by Windows 10 in July 2015. Support for IE10 on Windows Server 2012 and Windows Embedded 8 Standard ended on January 31, 2020. Market share had fallen to 1.06% by October 2020. Windows 8 introduced major changes to the operating system's platform and user interface intended to improve its user experience on tablets, where Windows was now competing with mobile operating systems, including Android and iOS. In particular, these changes included a touch-optimized Windows shell based on Microsoft's Metro design language and the Start screen, a new platform for developing apps with an emphasis on touchscreen input, integration with online services, and Windows Store, an online distribution for downloading and purchasing new software, and a new keyboard shortcut for screenshots. Many of these features were adopted from Windows Phone. Windows 8 added support for USB 3.0, Advanced Format hard drives, near field communications, and cloud computing. Additional security features were introduced, such as built-in antivirus software, integration with Microsoft SmartScreen phishing filtering service and support for UEFI Secure Boot on supported devices. Windows 8 was released to a mixed critical reception. Although reaction towards its performance improvements, security enhancements, and improved support for touchscreen devices was positive, the new user interface of the operating system was widely criticized for being potentially confusing and difficult to learn, especially when used with a keyboard and mouse instead of a touchscreen. Despite these shortcomings, 60 million Windows 8 licenses were sold through January 2013, a number that included both upgrades and sales to OEMs for new PCs. In August 2019, computer experts reported that the BlueKeep security vulnerability, , that potentially affects older unpatched Microsoft Windows versions via the program's Remote Desktop Protocol, allowing for the possibility of remote code execution, may now include related flaws, collectively named DejaBlue, affecting newer Windows versions (i.e., Windows 7 and all recent versions). In addition, experts reported a Microsoft security vulnerability, , based on legacy code involving ctfmon.exe that affects all Windows versions from the older Windows XP version to the most recent Windows 10 versions; a patch to correct the flaw is currently available. Development history Early development Windows 8 development started before Windows 7 had shipped in 2009. At the Consumer Electronics Show in January 2011, it was announced that the next version of Windows would add support for ARM system-on-chips alongside the existing x86 processors produced by vendors, especially AMD and Intel. Windows division president Steven Sinofsky demonstrated an early build of the port on prototype devices, while Microsoft CEO Steve Ballmer announced the company's goal for Windows to be "everywhere on every kind of device without compromise." Details also began to surface about a new application framework for Windows 8 codenamed "Jupiter", which would be used to make "immersive" applications using XAML (similarly to Windows Phone and Silverlight) that could be distributed via a new packaging system and a rumored application store. The earliest build of Windows 8 is build 7700, compiled in January 2010. The build was identical to Windows 7 except for the wallpaper being different - the same one from the Beta and Release Candidate. In addition, there were references to Windows 8 in this build. In late 2010, an optional 3D desktop user interface for high-end systems named "Wind" was rumored. Two milestone releases of Windows 8 and one of Windows Server 2012 leaked to the general public. Milestone 1, Build 7850, was leaked on April 12, 2011. It was the first build where the text of a window was written centered instead of aligned to the left. It was also probably the first appearance of the Metro-style font, and its wallpaper had the text shhh. let's not leak our hard work. However, its detailed build number reveals that the build was created on September 22, 2010. The leaked copy was Enterprise edition, with other editions leaking later. In 2020, it was discovered that Metro existed in this build, after enabling the 'Redpill'. The start screen was very primitive, being a white screen with gray tiles. The charms bar was also included, but was unusable. The OS still reads as "Windows 7". Milestone 2, Build 7955, was leaked on April 25, 2011. The traditional Blue Screen of Death (BSoD) was replaced by a new black screen, although it was later reverted to a different blue color. This build introduced a new ribbon in Windows Explorer. The "Windows 7" logo was temporarily replaced with text displaying "Microsoft Confidential". Both builds 7850 and 7955 leaked alongside Windows Server 2012 build 7959. On June 17, 2011, build 7989 64-bit edition was leaked. It introduced a new boot screen featuring the same Betta fish as the default Windows 7 Beta wallpaper, which was later replaced, and the circling dots as featured in the final (although the final version comes with smaller circling dots throbber). It also had the text Welcome below them, although this was scrapped. The boot screen was not new to this build though - it came from build 7973, a slightly earlier build. It is worth mentioning that most of these leaks "hid" the main Metro UI features that were to come in tweak known as Redlock in order to prevent relevant leaks. A patch named Redpill was necessary to reveal the new Metro UI as well as the redesigned Start Screen, Lock Screen and apps. Several applications have tried to replicate this patch as closely as possible, although one called Redlock is the most accurate, supporting the enabling of builds' Metro UI from 7850-8056. It also worked on the Developer Preview. This build also leaked in the x86 architecture as a debug build, with the setup having a slight change - the theme was now Windows Basic in setup, rather than Classic. Build 8008 was the first build to remove the User Tile. A new wallpaper was introduced and Metro was updated to be more like the final version of Windows 8. On June 1, 2011, Microsoft unveiled Windows 8's new user interface, as well as additional features at both Computex Taipei and the D9: All Things Digital conference in California. The "Building Windows 8" blog launched on August 15, 2011, featuring details surrounding Windows 8's features and its development process. Previews As Windows 8 transitioned away from being in the Milestone phase of development, the Developer Preview was beginning to take shape. Build 8032 changed the branding to Windows Developer Preview and was the last build to use Windows 7 branding anywhere. Build 8056 introduced several changes to the interface and small stability improvements. Metro was updated to be more like the Metro in Developer Preview (although it was still different) and a new wallpaper was introduced. Microsoft unveiled more Windows 8 features and improvements on the first day of the Build conference on September 13, 2011. Microsoft released the first public beta build of Windows 8, Windows Developer Preview (build 8102) at the event. A Samsung tablet running the build was also distributed to conference attendees. The build was released for download later that day in standard 32-bit and 64-bit variants, plus a special 64-bit variant which included SDKs and developer tools (Visual Studio Express and Expression Blend) for developing Metro-style apps. The Windows Store was announced during the presentation, but was not available in this build. According to Microsoft, there were about 535,000 downloads of the developer preview within the first 12 hours of its release. Originally set to expire on March 11, 2012, in February 2012 the Developer Preview's expiry date was changed to January 15, 2013. The next step was the Consumer Preview, sometimes called Windows 8 Beta in the builds before it. Build 8118 is the earliest leaked post-Developer Preview build. This build disables Redpill, and Metro can be manually enabled through the editing of system files. Build 8128 removed Redpill, and Metro was enabled by default with no way to disable it (although build 8102 is being distributed by Microsoft with Redpill already applied and can be disabled with a registry key). Build 8176 featured new branding - Windows 8 Beta. The Consumer Preview wallpapers have now been added, and the setup color has been changed to be the same as the final Consumer Preview. Build 8195 is largely the same as 8176, although it removes the Start Button from the taskbar. While the start button could be removed in early Milestone 2 (and this persisted through Windows 8 development) with a registry key, this build disabled it by default with no way to turn it back on. The branding is now identical to the Consumer Preview. On February 17, 2012, Microsoft unveiled a new logo to be adopted for Windows 8. Designed by Pentagram partner Paula Scher, the Windows logo was changed to resemble a set of four window panes. Additionally, the entire logo is now rendered in a single solid color. On February 29, 2012, Microsoft released Windows 8 Consumer Preview, the beta version of Windows 8, build 8250. Alongside other changes, the build brought over the big change from build 8195: removing the Start button from the taskbar for the first time in a public build since its debut on Windows 95; according to Windows manager Chaitanya Sareen, the Start button was removed to reflect their view that on Windows 8, the desktop was an "app" itself, and not the primary interface of the operating system. Windows president Steven Sinofsky said more than 100,000 changes had been made since the developer version went public. The day after its release, Windows 8 Consumer Preview had been downloaded over one million times. Like the Developer Preview, the Consumer Preview expired on January 15, 2013. Development on the third and final preview of Windows 8, the Release Preview, began shortly after Consumer Preview (note: build 8277 was compiled on February 8, 2012, before 8250). Build 8330 was a build in between the Consumer and Release Previews. This build includes a new default wallpaper and several changes, such as the new logo replacing the old one and appearing in the About Windows dialog box. Many other builds may exist or were released until Japan's Developers Day conference when Steven Sinofsky announced that Windows 8 Release Preview (build 8400) would be released during the first week of June. On May 28, 2012, Windows 8 Release Preview (Standard Simplified Chinese x64 edition, not China-specific variant, build 8400) was leaked online on various Chinese and BitTorrent websites. On May 31, 2012, Windows 8 Release Preview was released to the public by Microsoft. Major items in the Release Preview included the addition of Sports, Travel, and News apps, along with an integrated variant of Adobe Flash Player in Internet Explorer. Like the Developer Preview and the Consumer Preview, the release preview expired on January 15, 2013. Release With the Release Preview of Windows 8 finished, Microsoft began work on the final release. Build 8423 is the last leaked build to contain Aero. It was dropped in build 8432 and seen for two builds after 8423. Build 8438 removed Desktop Gadgets. It was identical to 8432, which removed Aero. This build and the x86 variant of build 8330 were built in the interestingly named 'fbl_ie_longhorn' branch. Build 8888 was leaked in December 2014, and was identical to the RTM with the exception of the timebomb and missing apps. On August 1, 2012, Windows 8 (build 9200) was released to manufacturing with the build number 6.2.9200.16384. Microsoft planned to hold a launch event on October 25, 2012 and release Windows 8 for general availability on the next day. However, only a day after its release to manufacturing, a copy of the final version of Windows 8 Enterprise N (a variant for European markets which lacks bundled media players to comply with an antitrust ruling) leaked online, followed by leaks of the final versions of Windows 8 Pro and Enterprise a few days later. On August 15, 2012, Windows 8 was made available to download for MSDN and TechNet subscribers. Windows 8 was made available to Software Assurance customers on August 16, 2012. Windows 8 was made available for students with a DreamSpark Premium subscription on August 22, 2012, earlier than advertised. Windows 8 became generally available for download to all MSDN and TechNet customers on August 15 and for retail purchase on October 26, 2012. Relatively few changes were made from the Release Preview to the final version; these included updated versions of its pre-loaded apps, the renaming of Windows Explorer to File Explorer, the replacement of the Aero Glass theme from Windows Vista and 7 with a new flat and solid-color theme as seen in build 8432, and the addition of new background options for the Start screen, lock screen, and desktop. Prior to its general availability on October 26, 2012, updates were released for some of Windows 8's bundled apps, and a "General Availability Cumulative Update" (which included fixes to improve performance, compatibility, and battery life) was released on Tuesday, October 9, 2012. Microsoft indicated that due to improvements to its testing infrastructure, general improvements of this nature are to be released more frequently through Windows Update instead of being relegated to OEMs and service packs only. Microsoft began an advertising campaign centered around Windows 8 and its Surface tablet in October 2012, starting with its first television advertisement premiering on October 14, 2012. Microsoft's advertising budget of US$1.5–1.8 billion was significantly larger than the US$200 million campaign used to promote Windows 95. As part of its campaign, Microsoft set up 34 pop-up stores inside malls to showcase the Surface product line, provided training for retail employees in partnership with Intel, and collaborated with the electronics store chain Best Buy to design expanded spaces to showcase devices. In an effort to make retail displays of Windows 8 devices more "personal", Microsoft also developed a character known in English-speaking markets as "Allison Brown", whose fictional profile (including personal photos, contacts, and emails) is also featured on demonstration units of Windows 8 devices. All Windows 7 PCs plan to offer a new Windows 8 upgrade on December 31, 2012, and Microsoft upgraded it as a product of currently supported Windows 7 PCs in January 2013 via Windows Update. In May 2013, Microsoft launched a new television campaign for Windows 8 illustrating the capabilities and pricing of Windows 8 tablets in comparison to the iPad, which featured the voice of Siri remarking on the iPad's limitations in a parody of Apple's "Get a Mac" advertisements. On June 12, 2013 during game 1 of the 2013 Stanley Cup Finals, Microsoft premiered the first ad in its "Windows Everywhere" campaign, which promoted Windows 8, Windows Phone 8, and the company's suite of online services as an interconnected platform. New and changed features New features and functionality in Windows 8 include a faster startup through UEFI integration and the new "Hybrid Boot" mode (which hibernates the Windows kernel on shutdown to speed up the subsequent boot), a new lock screen with a clock and notifications, and the ability for enterprise users to create live USB variants of Windows (known as Windows To Go). Windows 8 also adds native support for USB 3.0 devices, which allow for faster data transfers and improved power management with compatible devices, and hard disk 4KB Advanced Format support, as well as support for near field communication to facilitate sharing and communication between devices. Windows Explorer, which has been renamed File Explorer, now includes a ribbon in place of the command bar. File operation dialog boxes have been updated to provide more detailed statistics, the ability to pause file transfers, and improvements in the ability to manage conflicts when copying files. A new "File History" function allows incremental revisions of files to be backed up to and restored from a secondary storage device, while Storage Spaces allows users to combine different sized hard disks into virtual drives and specify mirroring, parity, or no redundancy on a folder-by-folder basis. For easier management of files and folders, Windows 8 introduces the ability to move selected files or folders via drag and drop from a parent folder into a subfolder listed within the breadcrumb hierarchy of the address bar in File Explorer. Task Manager has been redesigned, including a new processes tab with the option to display fewer or more details of running applications and background processes, a heat map using different colors indicating the level of resource usage, network and disk counters, grouping by process type (e.g. applications, background processes and Windows processes), friendly names for processes and a new option which allows users to search the web to find information about obscure processes. Additionally, the Blue Screen of Death has been updated with a simpler and modern design with less technical information displayed. Safety and security New security features in Windows 8 include two new authentication methods tailored towards touchscreens (PINs and picture passwords), the addition of antivirus capabilities to Windows Defender (bringing it in parity with Microsoft Security Essentials). SmartScreen filtering integrated into Windows, Family Safety offers Parental controls, which allows parents to monitor and manage their children's activities on a device with activity reports and safety controls. Windows 8 also provides integrated system recovery through the new "Refresh" and "Reset" functions, including system recovery from USB drive. Windows 8's first security patches would be released on November 13, 2012; it would contain three fixes deemed "critical" by the company. Windows 8 supports a feature of the UEFI specification known as "Secure boot", which uses a public-key infrastructure to verify the integrity of the operating system and prevent unauthorized programs such as bootkits from infecting the device's boot process. Some pre-built devices may be described as "certified" by Microsoft; these must have secure boot enabled by default, and provide ways for users to disable or re-configure the feature. ARM-based Windows RT devices must have secure boot permanently enabled. Online services and functionality Windows 8 provides heavier integration with online services from Microsoft and others. A user can now log into Windows with a Microsoft account, which can be used to access services and synchronize applications and settings between devices. Windows 8 also ships with a client app for Microsoft's SkyDrive cloud storage service, which also allows apps to save files directly to SkyDrive. A SkyDrive client for the desktop and File Explorer is not included in Windows 8, and must be downloaded separately. Bundled multimedia apps are provided under the Xbox brand, including Xbox Music, Xbox Video, and the Xbox SmartGlass companion for use with an Xbox 360 console. Games can integrate into an Xbox Live hub app, which also allows users to view their profile and Gamerscore. Other bundled apps provide the ability to link Flickr and Facebook. Due to Facebook Connect service changes, Facebook support is disabled in all bundled apps effective June 8, 2015. Internet Explorer 10 is included as both a desktop program and a touch-optimized app, and includes increased support for HTML5, CSS3, and hardware acceleration. The Internet Explorer app does not support plugins or ActiveX components, but includes a variant of Adobe Flash Player that is optimized for touch and low power usage. Initially, Adobe Flash would only work on sites included on a "Compatibility View" whitelist; however, after feedback from users and additional compatibility tests, an update in March 2013 changed this behavior to use a smaller blacklist of sites with known compatibility issues instead, allowing Flash to be used on most sites by default. The desktop variant does not contain these limitations. Windows 8 also incorporates improved support for mobile broadband; the operating system can now detect the insertion of a SIM card and automatically configure connection settings (including APNs and carrier branding), and reduce its Internet usage to conserve bandwidth on metered networks. Windows 8 also adds an integrated airplane mode setting to globally disable all wireless connectivity as well. Carriers can also offer account management systems through Windows Store apps, which can be automatically installed as a part of the connection process and offer usage statistics on their respective tile. Windows Store apps Windows 8 introduces a new style of application, Windows Store apps. According to Microsoft developer Jensen Harris, these apps are to be optimized for touchscreen environments and are more specialized than current desktop applications. Apps can run either in a full-screen mode or be snapped to the side of a screen. Apps can provide toast notifications on screen or animate their tiles on the Start screen with dynamic content. Apps can use "contracts"; a collection of hooks to provide common functionality that can integrate with other apps, including search and sharing. Apps can also provide integration with other services; for example, the People app can connect to a variety of different social networks and services (such as Facebook, Skype, and People service), while the Photos app can aggregate photos from services such as Facebook and Flickr. Windows Store apps run within a new set of APIs known as Windows Runtime, which supports programming languages such as C, C++, Visual Basic .NET, C#, along with HTML5 and JavaScript. If written in some "high-level" languages, apps written for Windows Runtime can be compatible with both Intel and ARM variants of Windows, otherwise they are not binary code compatible. Components may be compiled as Windows Runtime Components, permitting consumption by all compatible languages. To ensure stability and security, apps run within a sandboxed environment, and require permissions to access certain functionality, such as accessing the Internet or a camera. Retail variants of Windows 8 are only able to install these apps through Windows Store — a namesake distribution platform that offers both apps, and listings for desktop programs certified for comparability with Windows 8. A method to sideload apps from outside Windows Store is available to devices running Windows 8 Enterprise and joined to a domain; Windows 8 Pro and Windows RT devices that are not part of a domain can also sideload apps, but only after special product keys are obtained through volume licensing. The term "Immersive app" had been used internally by Microsoft developers to refer to the apps prior to the first official presentation of Windows 8, after which they were referred to as "Metro-style apps" in reference to the Metro design language. The term was phased out in August 2012; a Microsoft spokesperson denied rumors that the change was related to a potential trademark issue, and stated that "Metro" was only a codename that would be replaced prior to Windows 8's release. Following these reports, the terms "Modern UI-style apps", "Windows 8-style apps" and "Windows Store apps" began to be used by various Microsoft documents and material to refer to the new apps. In an interview on September 12, 2012, Soma Somasegar (vice president of Microsoft's development software division) confirmed that "Windows Store apps" would be the official term for the apps. An MSDN page explaining the Metro design language uses the term "Modern design" to refer to the language as a whole. Web browsers Exceptions to the restrictions faced by Windows Store apps are given to web browsers. The user's default browser can distribute a Metro-style web browser in the same package as the desktop variant, which has access to functionality unavailable to other apps, such as being able to permanently run in the background, use multiple background processes, and use Windows API code instead of WinRT (allowing for code to be re-used with the desktop variant, while still taking advantage of features available to Windows Store apps, such as charms). Microsoft advertises this exception privilege "New experience enabled" (formerly "Metro-style enabled"). The developers of both Chrome and Firefox committed to developing Metro-style variants of their browsers; while Chrome's "Windows 8 mode" (discontinued on Chrome version 49) uses a full-screen version of the existing desktop interface, Firefox's variant (which was first made available on the "Aurora" release channel in September 2013) uses a touch-optimized interface inspired by the Android variant of Firefox. In October 2013, Chrome's app was changed to mimic the desktop environment used by Chrome OS. Development of the Firefox app for Windows 8 has since been cancelled, citing a lack of user adoption for the beta versions. Interface and desktop Windows 8 introduces significant changes to the operating system's user interface, many of which are aimed at improving its experience on tablet computers and other touchscreen devices. The new user interface is based on Microsoft's Metro design language and uses a Start screen similar to that of Windows Phone 7 as the primary means of launching applications. The Start screen displays a customizable array of tiles linking to various apps and desktop programs, some of which can display constantly updated information and content through "live tiles". As a form of multi-tasking, apps can be snapped to the side of a screen. Alongside the traditional Control Panel, a new simplified and touch-optimized settings app known as "PC Settings" is used for basic configuration and user settings. It does not include many of the advanced options still accessible from the normal Control Panel. A vertical toolbar known as the charms (accessed by swiping from the right edge of a touchscreen, swiping from the right edge of a touchpad, or pointing the cursor at hotspots in the right corners of a screen) provides access to system and app-related functions, such as search, sharing, device management, settings, and a Start button. The traditional desktop environment for running desktop applications is accessed via a tile on the Start screen. The Start button on the taskbar from previous versions of Windows has been converted into a hotspot (or "hot corner") in the lower-left corner of the screen, which displays a large tooltip displaying a thumbnail of the Start screen. However, Windows 8.1 added the start button back to the taskbar after many complaints, but removed the preview thumbnail. Swiping from the left edge of a touchscreen or clicking in the top-left corner of the screen allows one to switch between apps and Desktop. Pointing the cursor in the top-left corner of the screen and moving down reveals a thumbnail list of active apps. Aside from the removal of the Start button and the replacement of the Aero Glass theme with a flatter and solid-colored design, the desktop interface on Windows 8 is similar to that of Windows 7. Removed features Several notable features were removed in Windows 8; support for playing DVD-Video was removed from Windows Media Player due to the cost of licensing the necessary decoders (especially for devices which do not include optical disc drives at all) and the prevalence of online streaming services. For the same reasons, Windows Media Center is not included by default on Windows 8, but Windows Media Center and DVD playback support could be purchased in the "Pro Pack" (which upgrades the system to Windows 8 Pro) or "Media Center Pack" add-on for Windows 8 Pro. As with prior versions, third-party DVD player software can still be used to enable DVD playback. Backup and Restore, the backup component of Windows, was deprecated. It still shipped with Windows 8 and continues to work on preset schedules, but it was pushed to the background and can only be accessed through a Control Panel applet called "Windows 7 File Recovery". Shadow Copy, a component of Windows Explorer that once saved previous versions of changed files, no longer protects local files and folders. It can only access previous versions of shared files stored on a Windows Server computer. The subsystem on which these components worked, however, is still available for other software to use. Hardware requirements PCs The minimum system requirements for Windows 8 are slightly higher than those of Windows 7. The CPU must support the Physical Address Extension (PAE), NX bit, and SSE2. Windows Store apps require a screen resolution of 1024×768 or higher to run; a resolution of 1366×768 or higher is required to use the snap functionality. To receive certification, Microsoft requires candidate x86 systems to resume from standby in 2 seconds or less. Microsoft's Connected Standby specification, which hardware vendors may optionally comply with, sets new power consumption requirements that extend above the above minimum specifications. Included in this standard are a number of security-specific requirements designed to improve physical security, notably against Cold Boot Attacks. 32-bit SKUs of Windows 8 only support a maximum of 4 GB of RAM. 64-bit SKUs, however support more: Windows 8 x64 supports 128 GB while Windows 8 Pro and Enterprise x64 support 512 GB. In January 2016, Microsoft announced that it would no longer support Windows 8.1 or 7 on devices using Intel's Skylake CPU family effective July 17, 2018, and that all future CPU microarchitectures, as well as Skylake systems after this date, would only be supported on Windows 10. After the deadline, only critical security updates were to be released for users on these platforms. After this new policy faced criticism from users and enterprise customers, Microsoft partially retracted the change and stated that both operating systems would remain supported on Skylake hardware through the end of their Extended support lifecycle. Windows 8.1 remains officially unsupported on all newer CPU families, and neither AMD or Intel will provide official chipset drivers for Windows operating systems other than Windows 10. However, on August 2016, Microsoft again extended the Skylake support policy until the end of support for Windows 7 and 8.1 (2020 and 2023, respectively). Tablets and convertibles Microsoft released minimum hardware requirements for tablet and laplet devices to be "certified" for Windows 8 and defined a convertible form factor as a standalone device that combines the PC, display, and rechargeable power source with a mechanically attached keyboard and pointing device in a single chassis. A convertible can be transformed into a tablet where the attached input devices are hidden or removed leaving the display as the only input mechanism. On March 12, 2013, Microsoft amended its certification requirements to only require that screens on tablets have a minimum resolution of 1024×768 (down from the previous 1366×768). The amended requirement is intended to allow "greater design flexibility" for future products. Updated certification requirements were implemented to coincide with Windows 8.1. As of 2014, all certified devices with integrated displays must contain a 720p webcam and higher quality speakers and microphones, while all certified devices that support Wi-Fi must support Bluetooth as well. As of 2015, all certified devices must contain Trusted Platform Module 2.0 chips. Editions Windows 8 is available in three different editions, of which the lowest edition, branded simply as Windows 8, and Windows 8 Pro, were sold at retail in most countries, and as pre-loaded software on new computers. Each edition of Windows 8 includes all of the capabilities and features of the edition below it, and add additional features oriented towards their market segments. For example, Pro added BitLocker, Hyper-V, the ability to join a domain, and the ability to install Windows Media Center as a paid add-on. Users of Windows 8 can purchase a "Pro Pack" license that upgrades their system to Windows 8 Pro through Add features to Windows. This license also includes Windows Media Center. Windows 8 Enterprise contains additional features aimed towards business environments, and is only available through volume licensing. A port of Windows 8 for ARM architecture, Windows RT, is marketed as an edition of Windows 8, but was only included as pre-loaded software on devices specifically developed for it. Windows 8 was distributed as a retail box product on DVD, and through a digital download that could be converted into DVD or USB install media. As part of a launch promotion, Microsoft offered Windows 8 Pro upgrades at a discounted price of US$39.99 online, or $69.99 for retail box from its launch until January 31, 2013; afterward the Windows 8 price has been $119.99 and the Pro price $199.99. Those who purchased new PCs pre-loaded with Windows 7 Home Basic, Home Premium, Professional, or Ultimate between June 2, 2012 and January 31, 2013 could digitally purchase a Windows 8 Pro upgrade for US$14.99. Several PC manufacturers offered rebates and refunds on Windows 8 upgrades obtained through the promotion on select models, such as Hewlett-Packard (in the U.S. and Canada on select models), and Acer (in Europe on selected Ultrabook models). During these promotions, the Windows Media Center add-on for Windows 8 Pro was also offered for free. Unlike previous versions of Windows, Windows 8 was distributed at retail in "Upgrade" licenses only, which require an existing version of Windows to install. The "full version software" SKU, which was more expensive but could be installed on computers without an eligible OS or none at all, was discontinued. In lieu of full version, a specialized "System Builder" SKU was introduced. The "System Builder" SKU replaced the original equipment manufacturer (OEM) SKU, which was only allowed to be used on PCs meant for resale but added a "Personal Use License" exemption that officially allowed its purchase and personal use by users on homebuilt computers. Retail distribution of Windows 8 has since been discontinued in favor of Windows 8.1. Unlike 8, 8.1 is available as "full version software" at both retail and online for download that does not require a previous version of Windows in order to be installed. Pricing for these new copies remain identical. With the retail release returning to full version software for Windows 8.1, the "Personal Use License" exemption was removed from the OEM SKU, meaning that end users building their own PCs for personal use must use the full retail variant in order to satisfy the Windows 8.1 licensing requirements. Windows 8.1 with Bing is a special OEM-specific SKU of Windows 8.1 subsidized by Microsoft's Bing search engine. Software compatibility The three desktop editions of Windows 8 support 32-bit and 64-bit architectures; retail copies of Windows 8 include install DVDs for both architectures, while the online installer automatically installs the variant corresponding with the architecture of the system's existing Windows installation. The 32-bit variant runs on CPUs compatible with x86 architecture 3rd generation (known as IA-32) or newer, and can run 32-bit and 16-bit applications, although 16-bit support must be enabled first. (16-bit applications are developed for CPUs compatible with x86 2nd generation, first conceived in 1978. Microsoft started moving away from this architecture after Windows 95.) The 64-bit variant runs on CPUs compatible with x86 8th generation (known as x86-64, or x64) or newer, and can run 32-bit and 64-bit programs. 32-bit programs and operating system are restricted to supporting only of memory while 64-bit systems can theoretically support of memory. 64-bit operating systems require a different set of device drivers than those of 32-bit operating systems. Windows RT, the only edition of Windows 8 for systems with ARM processors, only supports applications included with the system (such as a special variant of Office 2013), supplied through Windows Update, or Windows Store apps, to ensure that the system only runs applications that are optimized for the architecture. Windows RT does not support running IA-32 or x64 applications. Windows Store apps can either support both the x86 and ARM architectures, or compiled to support a specific architecture. Reception Pre-release Following the unveiling of Windows 8, Microsoft faced criticism (particularly from free software supporters) for mandating that devices receiving its optional certification for Windows 8 have secure boot enabled by default using a key provided by Microsoft. Concerns were raised that secure boot could prevent or hinder the use of alternate operating systems such as Linux. In a post discussing secure boot on the Building Windows 8 blog, Microsoft developer Tony Mangefeste indicated that vendors would provide means to customize secure boot, stating that "At the end of the day, the customer is in control of their PC. Microsoft's philosophy is to provide customers with the best experience first, and allow them to make decisions themselves." Microsoft's certification guidelines for Windows 8 ultimately revealed that vendors would be required to provide means for users to re-configure or disable secure boot in their device's UEFI firmware. It also revealed that ARM devices (Windows RT) would be required to have secure boot permanently enabled, with no way for users to disable it. However, Tom Warren of The Verge noted that other vendors have implemented similar hardware restrictions on their own ARM-based tablet and smartphone products (including those running Microsoft's own Windows Phone platform), but still argued that Microsoft should "keep a consistent approach across ARM and x86, though, not least because of the number of users who'd love to run Android alongside Windows 8 on their future tablets." No mandate is made regarding the installation of third-party certificates that would enable running alternative programs. Several notable video game developers criticized Microsoft for making its Windows Store a closed platform subject to its own regulations, as it conflicted with their view of the PC as an open platform. Markus "Notch" Persson (creator of the indie game Minecraft), Gabe Newell (co-founder of Valve and developer of software distribution platform Steam), and Rob Pardo from Activision Blizzard voiced concern about the closed nature of the Windows Store. However, Tom Warren of The Verge stated that Microsoft's addition of the Store was simply responding to the success of both Apple and Google in pursuing the "curated application store approach." Critical reception Reviews of the various editions of Windows 8 were mixed to negative. Tom Warren of The Verge said that although Windows 8's emphasis on touch computing was significant and risked alienating desktop users, he felt that Windows 8 tablets "[make] an iPad feel immediately out of date" due to the capabilities of the operating system's hybrid model and increased focus on cloud services. David Pierce of The Verge described Windows 8 as "the first desktop operating system that understands what a computer is supposed to do in 2012" and praised Microsoft's "no compromise" approach and the operating system's emphasis on Internet connectivity and cloud services. Pierce also considered the Start Screen to be a "brilliant innovation for desktop computers" when compared with "folder-littered desktops on every other OS" because it allows users to interact with dynamic information. In contrast, an ExtremeTech article said it was Microsoft "flailing" and a review in PC Magazine condemned the Metro-style user interface. Some of the included apps in Windows 8 were considered to be basic and lacking in functionality, but the Xbox apps were praised for their promotion of a multi-platform entertainment experience. Other improvements and features (such as File History, Storage Spaces, and the updated Task Manager) were also regarded as positive changes. Peter Bright of Ars Technica wrote that while its user interface changes may overshadow them, Windows 8's improved performance, updated file manager, new storage functionality, expanded security features, and updated Task Manager were still positive improvements for the operating system. Bright also said that Windows 8's duality towards tablets and traditional PCs was an "extremely ambitious" aspect of the platform as well, but criticized Microsoft for emulating Apple's model of a closed distribution platform when implementing the Windows Store. The interface of Windows 8 has been the subject of negative reaction. Bright wrote that its system of hot corners and edge swiping "wasn't very obvious" due to the lack of instructions provided by the operating system on the functions accessed through the user interface, even by the video tutorial added on the RTM release (which only instructed users to point at corners of the screen or swipe from its sides). Despite this "stumbling block", Bright said that Windows 8's interface worked well in some places, but began to feel incoherent when switching between the "Metro" and desktop environments, sometimes through inconsistent means. Tom Warren of The Verge wrote that the new interface was "as stunning as it is surprising", contributing to an "incredibly personal" experience once it is customized by the user, but had a steep learning curve, and was awkward to use with a keyboard and mouse. He noted that while forcing all users to use the new touch-oriented interface was a risky move for Microsoft as a whole, it was necessary in order to push development of apps for the Windows Store. Others, such as Adrian Kingsley-Hughes from ZDNet, considered the interface to be "clumsy and impractical" due to its inconsistent design (going as far as considering it "two operating systems unceremoniously bolted together"), and concluded that "Windows 8 wasn't born out of a need or demand; it was born out of a desire on Microsoft's part to exert its will on the PC industry and decide to shape it in a direction—touch and tablets – that allows it to compete against, and remain relevant in the face of Apple's iPad." In 2013, Frank X. Shaw, a Microsoft corporate vice president, said that while many of the negative reviews were extreme, it was a "good thing" that Microsoft was "listening to feedback and improving a product". The American Customer Satisfaction Index (ACSI) reported a decline in Microsoft's customer satisfaction, the lowest it has been since Windows Vista. Market share and sales Microsoft says that 4 million users upgraded to Windows 8 over the weekend after its release, which CNET says was well below Microsoft's internal projections and was described inside the company as disappointing. On November 27, 2012, Microsoft announced that it had sold 40 million licenses of Windows 8 in the first month, surpassing the pace of Windows 7. However, according to research firm NPD, sales of devices running Windows in the United States had declined 21 percent compared to the same time period in 2011. As the holiday shopping season wrapped up, Windows 8 sales continued to lag, even as Apple reported brisk sales. The market research firm IDC reported an overall drop in PC sales for the quarter, and said the drop may have been partly due to consumer reluctance to embrace the new features of the OS and poor support from OEM for these features. This capped the first year of declining PC sales to the Asia Pacific region, as consumers bought more mobile devices than Windows PCs. Windows 8 surpassed Windows Vista in market share with a 5.1% usage rate according to numbers posted in July 2013 by Net Applications, with usage on a steady upward trajectory. However, intake of Windows 8 still lagged behind that of Windows Vista and Windows 7 at the same point in their release cycles. Windows 8's tablet market share also grew steadily, with 7.4% of tablets running Windows in Q1 2013 according to Strategy Analytics, up from nothing just a year before. However, this was still well below Android and iOS, which posted 43.4% and 48.2% market share respectively, although both operating systems had been on the market much longer than Windows 8. Strategy Analytics also noted "a shortage of top tier apps" for Windows tablets despite Microsoft strategy of paying developers to create apps for the operating system (in addition to for Windows Phone). In March 2013, Microsoft also amended its certification requirements to allow tablets to use the 1024×768 resolution as a minimum; this change is expected to allow the production of certified Windows 8 tablets in smaller form factors—a market which is currently dominated by Android-based tablets. Despite the reaction of industry experts, Microsoft reported that they had sold 100 million licenses in the first six months. This matched sales of Windows 7 over a similar period. This statistic includes shipments to channel warehouses which now need to be sold in order to make way for new shipments. In January 2014, Hewlett-Packard began a promotion for desktops running Windows 7, saying that it was "back by popular demand". Outside sources have suggested that this might be because HP or its customers thought the Windows 8 platform would be more appropriate for mobile computing than desktop computing, or that they were looking to attract customers forced to switch from XP who wanted a more familiar interface. In February 2014, Bloomberg reported that Microsoft would be lowering the price of Windows 8 licenses by 70% for devices that retail under US$250; alongside the announcement that an update to the operating system would allow OEMs to produce devices with as little as 1 GB of RAM and 16 GB of storage, critics felt that these changes would help Windows compete against Linux-based devices in the low-end market, particularly those running Chrome OS. Microsoft had similarly cut the price of Windows XP licenses to compete against the early waves of Linux-based netbooks. Reports also indicated that Microsoft was planning to offer cheaper Windows 8 licenses to OEMs in exchange for setting Internet Explorer's default search engine to Bing. Some media outlets falsely reported that the SKU associated with this plan, "Windows 8.1 with Bing", was a variant which would be a free or low-cost variant of Windows 8 for consumers using older versions of Windows. On April 2, 2014, Microsoft ultimately announced that it would be removing license fees entirely for devices with screens smaller than 9 inches, and officially confirmed the rumored "Windows 8.1 with Bing" OEM SKU on May 23, 2014. On the information gathered by Net Applications, adoption rate in March 2015 for Windows 8.1 was at 10.55%, while the original Windows 8 was at 3.52%. Chinese government ban In May 2014, the Government of China banned the internal purchase of Windows 8-based products under government contracts requiring "energy-efficient" devices. The Xinhua News Agency claimed that Windows 8 was being banned in protest of Microsoft's support lifecycle policy and the end of support for Windows XP (which, as of January 2014, had a market share of 49% in China), as the government "obviously cannot ignore the risks of running an OS without guaranteed technical support." However, Ni Guangnan of the Chinese Academy of Sciences had also previously warned that Windows 8 could allegedly expose users to surveillance by the United States government due to its heavy use of Internet-based services. In June 2014, state broadcaster China Central Television (CCTV) broadcast a news story further characterizing Windows 8 as a threat to national security. The story featured an interview with Ni Guangnan, who stated that operating systems could aggregate "sensitive user information" that could be used to "understand the conditions and activities of our national economy and society", and alleged that per documents leaked by Edward Snowden, the U.S. government had worked with Microsoft to retrieve encrypted information. Yang Min, a computer scientist at Fudan University, also stated that "the security features of Windows 8 are basically to the benefit of Microsoft, allowing them control of the users' data, and that poses a big challenge to the national strategy for information security." Microsoft denied the claims in a number of posts on the Chinese social network Sina Weibo, which stated that the company had never "assisted any government in an attack of another government or clients" or provided client data to the U.S. government, never "provided any government the authority to directly visit" or placed any backdoors in its products and services, and that it had never concealed government requests for client data. Windows 8.1 A feature update to Windows 8 known as Windows 8.1 was officially announced by Microsoft on May 14, 2013. Following a presentation devoted to it at Build 2013, a public beta version of the upgrade was released on June 26, 2013. Windows 8.1 was released to OEM hardware partners on August 27, 2013, and released publicly as a free upgrade through Windows Store on October 17, 2013. Volume license customers and subscribers to MSDN Plus and TechNet Plus were initially unable to obtain the RTM version upon its release; a spokesperson said the policy was changed to allow Microsoft to work with OEMs "to ensure a quality experience at general availability." However, after criticism, Microsoft reversed its decision and released the RTM build on MSDN and TechNet on September 9, 2013. Windows 8.1 addressed a number of criticisms faced by Windows 8 upon its release, with additional customization options for the Start screen, the restoration of a visible Start button on the desktop, the ability to snap up to four apps on a single display, and the ability to boot to the desktop instead of the Start screen. Windows 8's stock apps were also updated, a new Bing-based unified search system was added, SkyDrive was given deeper integration with the operating system, and a number of new stock apps, along with a tutorial, were added. Windows 8.1 also added support for 3D printing, Miracast media streaming, NFC printing, and Wi-Fi Direct. Microsoft marketed Windows 8.1 as an "update" rather than as a "service pack", as it had done with such revisions on previous versions of Windows. Nonetheless, Microsoft's support lifecycle policy treats Windows 8.1 similarly to previous Windows service packs: upgrading to 8.1 has been required to maintain access to mainstream support and updates after January 12, 2016. Although Windows 8 RTM is unsupported, Microsoft released an emergency security patch in May 2017 for Windows 8 RTM, as well as other unsupported versions of Windows (including Windows XP and Windows Server 2003), to address a vulnerability that was being leveraged by the WannaCry ransomware attack. Updates to apps published on Windows Store after July 1, 2019 will not be available to Windows 8 RTM users. Retail and OEM installations of Windows 8, Windows 8 Pro, and Windows RT can be upgraded through Windows Store free of charge. However, volume license customers, TechNet or MSDN subscribers and users of Windows 8 Enterprise must acquire a standalone installation media for 8.1 and install through the traditional Windows setup process, either as an in-place upgrade or clean install. This requires an 8.1 specific product key. See also List of operating systems Features new to Windows 8 References Further reading —Analysis of Windows 8 downgrade rights 2012 software IA-32 operating systems Tablet operating systems 8 X86-64 operating systems

Operating System (OS)

Operational Control Language Operational Control Language (OCL) is the control language of the IBM System/32, System/34 and System/36 minicomputer family. It is supported on IBM i's System/36 Environment for backwards compatibility purposes. It is similar to the older control languages JCL (System/370) and System/3, and unrelated to the later Control Language (System/38 and IBM AS/400), and REXX (AS/400). Overview On the IBM S/32, S/34 and S/36, OCL statements are used to directly load user or system programs into memory, assign system resources to them, and transfer system control to them in a process called execution. The fact that a program is stored on a computer's disk drive does not in itself cause the computer to process or execute the program. OCL statements can be entered manually from the keyboard, but are generally stored as a S/32, S/34, or S/36 procedure member. A procedure member is a freely editable member within a library, it is a source file. On the S/32, S/34, and S/36, procedures are not compiled, they are interpreted. Example OCL statements usually begin with two slashes and at least one space character. Here's an example of a procedure stored on a System/36 as member PROC1: ** Procedure PROC1 Optional documentation ** ** Written by Joe User 2006-05-29 ** ** // * 'PROC1 procedure is running' // * ' ' // IFF ACTIVE-'PROC2,PROC3' GOTO OKAY ** IFF means 'if false' ** ACTIVE-'name1,name2' means true ** if at least one of the listed programs is currently running ** GOTO xxx means skip to the statement ** that has a TAG xxx and resume processing // PAUSE 'Cannot continue because other Payroll is running' ** Halts execution with a message // CANCEL Stops execution of this procedure // TAG OKAY // IFF DATAF1-PFILE1 IFF DATAF1-PFILE2 GOTO NODELT // * 'Caution, Pay Data Exists' Displays information on terminal // * ' ' // * 'Press 1 to continue and DELETE existing files' // IFF '1'=?1R? CANCEL A parameter is indicated by question marks surrounding a number ** Using 1R between question marks indicates ** that the parameter is required ** and processing waits for user input. ** CANCEL means immediately go to end of job. // LOAD $DELET $DELET is used to delete files // RUN ** This program requires and processes, consumes, ** succeeding statements as data up until an END statement // IF DATAF1-PFILE1 SCRATCH UNIT-F1,LABEL-PFILE1 ** Conditionally deletes an existing disk file // IF DATAF1-PFILE2 SCRATCH UNIT-F1,LABEL-PFILE2 // END ** // TAG NODELT // LOAD PR101 PR101 could be an RPG or COBOL program // FILE NAME-PAYMAST,DISP-SHR PAYMAST is the payroll master file // FILE NAME-PFILE1,DISP-NEW,RECORDS-100,EXTEND-100 ** A new file PFILE1 is created and allocated ** 100 records are assigned to PFILE1 ** when all are used, the system tries to extend it by another 100 ** each time it fills. // RUN ** END statement is only necessary ** for those programs enabled ** to process any following statements as data ** Such data does not need to be formatted like OCL // SWITCH 1XX0XXXX Causes flags U1 through U8 to be SETON (1), OFF (0), or left as previously set (X) ** // LOCAL OFFSET-1,DATA-'PROC1' Places PROC1 in the Local Data Area (LDA) // LOCAL OFFSET-101,DATA-'?USER?' Substitutes the operator's User ID ** LDA is accessed via a data structure, UDS within an RPG program ** LDA and User switches (flags) remain available to succeeding programs ** until set otherwise ** Called sub-procedure members and loaded program's source code needs to be examined ** as to whether or not the LDA and User switches are actually read or altered // LOAD PR102 // FILE NAME-PAYMAST,DISP-SHR DISP-SHR means the file is shared, versus exclusive access ** Other programs can use PAYMAST at the same time // FILE NAME-PFILE,LABEL-PFILE1 NAME/LABEL is used when the RPG file name reference ** and the actual disk file label are different // RUN // RETURN Return to the calling procedure, otherwise end-of-job This procedure member incorporates a variety of OCL statements, also procedure control expressions (PCE), resources, that is mostly files are allocated, and several job steps, that is programs are executed. Comments are represented by an asterisk in column 1, and otherwise free-format. Or can be placed after the logical end of a statement, if there is no indicator for statement continuation onto the next line, like a trailing comma. External links IBM maintains manuals freely online and downloadable, including OCL 36. "System/36 Environment Programming" (1995) v6r1 "System/36 Environment Reference" (1995) v6r1 Scripting languages IBM operating systems

Operating System (OS)

Micro-Controller Operating Systems Micro-Controller Operating Systems (MicroC/OS, stylized as μC/OS) is a real-time operating system (RTOS) designed by Jean J. Labrosse in 1991. It is a priority-based preemptive real-time kernel for microprocessors, written mostly in the programming language C. It is intended for use in embedded systems. MicroC/OS allows defining several functions in C, each of which can execute as an independent thread or task. Each task runs at a different priority, and runs as if it owns the central processing unit (CPU). Lower priority tasks can be preempted by higher priority tasks at any time. Higher priority tasks use operating system (OS) services (such as a delay or event) to allow lower priority tasks to execute. OS services are provided for managing tasks and memory, communicating between tasks, and timing. History The MicroC/OS kernel was published originally in a three-part article in Embedded Systems Programming magazine and the book μC/OS The Real-Time Kernel by Jean J. Labrosse (). The author intended at first to simply describe the internals of a portable operating system he had developed for his own use, but later developed the OS as a commercial product in versions II and III. μC/OS-II Based on the source code written for μC/OS, and introduced as a commercial product in 1998, μC/OS-II is a portable, ROM-able, scalable, preemptive, real-time, deterministic, multitasking kernel for microprocessors, and digital signal processors (DSPs). It manages up to 64 tasks. Its size can be scaled (between 5 and 24 Kbytes) to only contain the features needed for a given use. Most of μC/OS-II is written in highly portable ANSI C, with target microprocessor-specific code written in assembly language. Use of the latter is minimized to ease porting to other processors. Uses in embedded systems μC/OS-II was designed for embedded uses. If the producer has the proper tool chain (i.e., C compiler, assembler, and linker-locator), μC/OS-II can be embedded as part of a product. μC/OS-II is used in many embedded systems, including: Avionics Medical equipment and devices Data communications equipment White goods (appliances) Mobile phones, personal digital assistants (PDAs), MIDs Industrial controls Consumer electronics Automotive Task states μC/OS-II is a multitasking operating system. Each task is an infinite loop and can be in any one of the following five states (see figure below additionally) Dormant Ready Running Waiting (for an event) Interrupted (interrupt service routine (ISR)) Further, it can manage up to 64 tasks. However, it is recommended that eight of these tasks be reserved for μC/OS-II, leaving an application up to 56 tasks. Kernels The kernel is the name given to the program that does most of the housekeeping tasks for the operating system. The boot loader hands control over to the kernel, which initializes the various devices to a known state and makes the computer ready for general operations. The kernel is responsible for managing tasks (i.e., for managing the CPU's time) and communicating between tasks. The fundamental service provided by the kernel is context switching. The scheduler is the part of the kernel responsible for determining which task runs next. Most real-time kernels are priority based. In a priority-based kernel, control of the CPU is always given to the highest priority task ready to run. Two types of priority-based kernels exist: non-preemptive and preemptive. Nonpreemptive kernels require that each task do something to explicitly give up control of the CPU. A preemptive kernel is used when system responsiveness is more important. Thus, μC/OS-II and most commercial real-time kernels are preemptive. The highest priority task ready to run is always given control of the CPU. Assigning tasks Tasks with the highest rate of execution are given the highest priority using rate-monotonic scheduling. This scheduling algorithm is used in real-time operating systems (RTOS) with a static-priority scheduling class. Managing tasks In computing, a task is a unit of execution. In some operating systems, a task is synonymous with a process, in others with a thread. In batch processing computer systems, a task is a unit of execution within a job. The system user of μC/OS-II is able to control the tasks by using the following features: Task feature Task creation Task stack & stack checking Task deletion Change a task's priority Suspend and resume a task Get information about a task Managing memory To avoid fragmentation, μC/OS-II allows applications to obtain fixed-sized memory blocks from a partition made of a contiguous memory area. All memory blocks are the same size, and the partition contains an integral number of blocks. Allocation and deallocation of these memory blocks is done in constant time and is a deterministic system. Managing time μC/OS-II requires that a periodic time source be provided to keep track of time delays and timeouts. A tick should occur between 10 and 1000 times per second, or Hertz. The faster the tick rate, the more overhead μC/OS-II imposes on the system. The frequency of the clock tick depends on the desired tick resolution of an application. Tick sources can be obtained by dedicating a hardware timer, or by generating an interrupt from an alternating current (AC) power line (50 or 60 Hz) signal. This periodic time source is termed a clock tick. After a clock tick is determined, tasks can be: Delaying a task Resume a delayed task Communicating between tasks Intertask or interprocess communication in μC/OS-II occurs via: semaphores, message mailbox, message queues, tasks, and interrupt service routines (ISRs). They can interact with each other when a task or an ISR signals a task through a kernel object called an event control block (ECB). The signal is considered to be an event. μC/OS-III μC/OS-III is the acronym for Micro-Controller Operating Systems Version 3, introduced in 2009 and adding functionality to the μC/OS-II RTOS. μC/OS-III offers all of the features and functions of μC/OS-II. The biggest difference is the number of supported tasks. μC/OS-II allows only 1 task at each of 255 priority levels, for a maximum of 255 tasks. μC/OS-III allows any number of application tasks, priority levels, and tasks per level, limited only by processor access to memory. μC/OS-II and μC/OS-III are currently maintained by Micrium, Inc., a subsidiary of Silicon Labs, and can be licensed per product or per product line. Uses in embedded systems The uses are the same as for μC/OS-II Task states μC/OS-III is a multitasking operating system. Each task is an infinite loop and can be in any one of five states (dormant, ready, running, interrupted, or pending). Task priorities can range from 0 (highest priority) to a maximum of 255 (lowest possible priority). Round robin scheduling When two or more tasks have the same priority, the kernel allows one task to run for a predetermined amount of time, named a quantum, and then selects another task. This process is termed round robin scheduling or time slicing. The kernel gives control to the next task in line if: The current task has no work to do during its time slice, or The current task completes before the end of its time slice, or The time slice ends. Kernels The kernel functionality for μC/OS-III is the same as for μC/OS-II. Managing tasks Task management also functions the same as for μC/OS-II. However, μC/OS-III supports multitasking and allows an application to have any number of tasks. The maximum number of tasks is limited by only the amount of computer memory (both code and data space) available to the processor. A task can be implemented viarunning to scheduled completion, in which the task deletes itself when it is finished, or more typically as an infinite loop, waiting for events to occur and processing those events. Managing memory Memory management is performed in the same way as in μC/OS-II. Managing time μC/OS-III offers the same time managing features as μC/OS-II. It also provides services to applications so that tasks can suspend their execution for user-defined time delays. Delays are specified by a number of either clock ticks, or hours, minutes, seconds, and milliseconds. Communicating between tasks Sometimes, a task or ISR must communicate information to another task, because it is unsafe for two tasks to access the same specific data or hardware resource at once. This can be resolved via an information transfer, termed inter-task communication. Information can be communicated between tasks in two ways: through global data, or by sending messages. When using global variables, each task or ISR must ensure that it has exclusive access to variables. If an ISR is involved, the only way to ensure exclusive access to common variables is to disable interrupts. If two tasks share data, each can gain exclusive access to variables by either disabling interrupts, locking the scheduler, using a semaphore, or preferably, using a mutual exclusion semaphore. Messages can be sent to either an intermediate object called a message queue, or directly to a task, since in μC/OS-III, each task has its own built-in message queue. Use an external message queue if multiple tasks are to wait for messages. Send a message directly to a task if only one task will process the data received. While a task waits for a message to arrive, it uses no CPU time. Ports A port involves three aspects: CPU, OS, and board specific (BSP) code. μC/OS-II and μC/OS-III have ports for most popular processors and boards in the market and are suitable for use in safety critical embedded systems such as aviation, medical systems, and nuclear installations. A μC/OS-III port involves writing or changing the contents of three kernel specific files: OS_CPU.H, OS_CPU_A.ASM, and OS_CPU_C.C. It is necessary to write or change the content of three CPU specific files: CPU.H, CPU_A.ASM, and CPU_C.C. Finally create or change a board support package (BSP) for the evaluation board or target board being used. A μC/OS-III port is similar to a μC/OS-II port. There are significantly more ports than listed here, and ports are subject to continuous development. Both μC/OS-II and μC/OS-III are supported by popular SSL/TLS libraries such as wolfSSL, which ensure security across all connections. Licensing Change After acquisition by Silicon Labs, Micrium in 2020 has changed to an Open Source licensing model in February 2020. This includes uC/OS III, all prior versions, all components (USB, file system, GUI, TCP/IP, etc). Documentation and Support In addition to a typical support forum, a number of well-written books are available. Books are available as free PDFs, or for low-cost purchase as hard-cover books. A number of books are each tailored to a particular microcontroller architecture / development platform. Paid support is available from Micrium and others. References Sources Protocol Support for μC/OS-II from Fusion Embedded Micrium-uCOS-III-UsersManual 1st Edition uC/OS-III: The Real-Time Kernel for the Renesas RX62N External links Summary of Commonly Used uC/OS-II Functions and Data Structures NiosII GCC with MicroC/OS μC/OS-II Reference Manual How to Get a μC/OS-II Application Running Real-time operating systems Embedded operating systems ARM operating systems Microkernel-based operating systems Microkernels

Operating System (OS)

Microsoft POSIX subsystem Microsoft POSIX subsystem is one of four subsystems shipped with the first versions of Windows NT, the other three being the Win32 subsystem which provided the primary API for Windows NT, plus the OS/2 and security subsystems. This subsystem implements only the POSIX.1 standard also known as IEEE Std 1003.1-1990 or ISO/IEC 9945-1:1990 primarily covering the kernel and C library programming interfaces which allowed a program written for other POSIX.1-compliant operating systems to be compiled and run under Windows NT. The Windows NT POSIX subsystem did not provide the interactive user environment parts of POSIX, originally standardized as POSIX.2. That is, Windows NT did not provide a POSIX shell nor any Unix commands like . The NT POSIX subsystem also did not provide any of the POSIX extensions that postdated the creation of Windows NT 3.1, such as those for POSIX Threads or POSIX IPC. The NT POSIX subsystem was included with the first versions of Windows NT because of 1980s US federal government requirements listed in Federal Information Processing Standard (FIPS) 151-2. Briefly, these documents required that certain types of government purchases be POSIX-compliant, so that if Windows NT had not included this subsystem, computing systems based on it would not have been eligible for some government contracts. Windows NT versions 3.5, 3.51 and 4.0 were certified as compliant with FIPS 151-2. The runtime environment of the subsystem is provided by two files: and . A POSIX application uses to communicate with the subsystem while communicating with to provide display capabilities on the Windows desktop. The POSIX subsystem was replaced in Windows XP and Windows Server 2003 by "Windows Services for UNIX", (SFU) which is based in part on OpenBSD code and other technology developed by Interix, a company later purchased by Microsoft. SFU was removed from later versions of Windows 8 and Windows Server 2012. SFU is logically, though not formally, replaced by the Windows Subsystem for Linux (WSL) in the Windows 10 Anniversary Update and Windows Server 2016 Version 1709 respectively. See also MKS Toolkit UWIN Cygwin UnxUtils Windows Subsystem for Linux References Further reading Windows components POSIX Compatibility layers

Operating System (OS)

Unisys OS 2200 programming languages OS 2200 has had several generations of compilers and linkers in its history supporting a wide variety of programming languages. In the first releases, the Exec II assembler (SLEUTH) and compilers were used. The assembler was quickly replaced with an updated version (ASM) designed specifically for the 1108 computer and Exec 8 but the early compilers continued in use for quite some time. Universal Compiling System The modern compiling system for OS 2200 is known as UCS, Universal Compiling System. The UCS architecture uses a common syntax analyzer, separate semantic front ends for each language and a common back-end and optimizer. There is also a common language runtime environment. The UCS system was developed starting in 1969 and initially included PL/I and Pascal. FORTRAN and COBOL were soon added. Ada was added later. The currently supported languages include COBOL, FORTRAN, C, and PLUS. PLUS, Programming Language for Unisys (originally UNIVAC) Systems, is a block structured language somewhat similar to Pascal which it predates. Legacy compilers Previous PLUS, COBOL and FORTRAN compilers are also still supported. An even earlier FORTRAN compiler (FORTRAN V), while no longer supported, is still in use for an application developed in the 1960s in that language. Compilers previously existed for ALGOL, Simula, BASIC, Lisp, NELIAC, JOVIAL, and other programming languages that are no longer in use on the ClearPath OS 2200 systems. Assembler The assembler, MASM, is heavily used both to obtain the ultimate in efficiency and to implement system calls that are not native to the programming language. Much of the MASM code in current use is a carryover from earlier days when compiler technology was not as advanced and when the machines were much slower and more constrained by memory size than today. Linking There are two linking systems used. The collector (@MAP) combines the output relocatable elements of the basic-mode compilers and assemblers into an absolute element which is directly executable. While this linker is intended primarily to support basic mode, the relocatable and absolute elements may contain extended-mode as well. This is often the case when an existing application is enhanced to use extended mode or call extended mode libraries but still contains some basic mode code. The Exec is an example of such a program. The linker (@LINK) is the modern linking environment which combines object modules into a new object module. It provides both static and dynamic linking capabilities. The most common usage is to combine the object modules of a program statically but to allow dynamic linking to libraries. Java OS 2200 provides a complete Java environment. Java on OS 2200 has evolved from an interesting additional capability for small servlets and tools to a full environment capable of handling large applications. The Virtual Machine for the Java Platform on ClearPath OS 2200 JProcessor is a Linux port of the Oracle Corporation Java release. The environment includes a full J2EE application server environment using the Tomcat open source web server from the Apache Software Foundation and the JBoss application server. All of this has been integrated with the OS 2200 security, databases, and recovery environment. References Unisys software

Operating System (OS)

LOBOS LOBOS (Linux OS Boots OS) is a software program (or "system") that allows remote booting ("netbooting") of a personal computer without using a BIOS. It allows one kernel to boot another kernel. LOBOS is part of an effort to move away from fixed, proprietary BIOSes to systems that allow more adaptability, especially with different physical peripheral devices. See also coreboot kexec Sources and external links Ronald Minnich, Advanced Computing Lab, Los Alamos National Laboratory Linux software

Operating System (OS)

Oberon (operating system) The Oberon System is a modular, single-user, single-process, multitasking operating system written in the programming language Oberon. It was originally developed in the late 1980s at ETH Zurich. The Oberon System has an unconventional visual text user interface (TUI) instead of a conventional command-line interface (CLI) or graphical user interface (GUI). This TUI was very innovative in its time and influenced the design of the Acme text editor for the Plan 9 from Bell Labs operating system. The latest version of the Oberon System, Project Oberon 2013, is still maintained by Niklaus Wirth and several collaborators, but older ETH versions of the system have been orphaned. The system also evolved into the multi-process, symmetric multiprocessing (SMP) capable A2 (formerly Active Object System (AOS), then Bluebottle), with a zooming user interface (ZUI). History The Oberon operating system was originally developed as part of the NS32032-based Ceres workstation project. It was written almost entirely (and since the 2013 version, is described entirely) in the Oberon programming language. The basic system was designed and implemented by Niklaus Wirth and Jürg Gutknecht and its design and implementation is fully documented in their book "Project Oberon". The user Interface and programmers reference is found in Martin Reiser's book "The Oberon System". It was later extended and ported to other hardware by a team at ETH Zurich and there was recognition in popular magazines. Wirth and Gutknecht (although being active computer science professors) refer to themselves as 'part-time programmers' in the book Project Oberon. In late 2013, a few months before his 80th birthday, Wirth published a second edition of Project Oberon. It details implementing the Oberon System using a reduced instruction set computer (RISC) CPU of his own design realized on a Xilinx field-programmable gate array (FPGA) board. It was presented at the symposium organized for his 80th birthday at ETH Zurich. In the meantime, several emulators for this version were implemented. According to Josef Templ, a former member of the developer group at Swiss Federal Institute of Technology in Zurich and later member of the Institut für Systemsoftware of Johannes Kepler University Linz, where one forked version (V4) was maintained, the genealogy of the different versions of the Oberon System is this: User interface Oberon has a text user interface (TUI), which is very different from a terminal user interface. It combines the point and click convenience of a graphical user interface (GUI) with the linguistic strength of a command-line interface (CLI) and is closely tied to the naming conventions of the Oberon language. Text appearing almost anywhere on a screen can be edited and used as command input. Commands are activated by a middle-mouse click on a text fragment of the form Module.Command (optionally followed by parameters, which are terminated by ~). A command is defined by any procedure which is exported and has an empty argument list. Parameters to the command must be defined before executing the middle click, and must be explicitly scanned and retrieved by the procedure. No checks or questions occur during command execution. This is sometimes called a non-modal user interface (UI). Nothing like a command prompt is needed. Although very different from a command line, the TUI is very efficient and powerful. A steep ascent in the early learning curve makes it a bit difficult at first. No questions are asked: this is a deliberate design decision, which needs getting used to. Most editors ask the user when closing a modified text: this is not the case in the Oberon System. The use of the TUI and programming interface is fully documented in Martin Reiser's book "The Oberon System". A short introduction to the user interface can be found on Niklaus Wirth's home page. The later Versions of System Oberon, Oberon V4 (V4, sometimes also named Linz-Oberon) and Oberon System 3 (or S3, sometimes also named ETH-Oberon or Spirit of Oberon), enhanced the basic interface with different but incompatible implementations for buttons, drop down menus, and other active elements. V4 used for that purpose a dedicated control character embedded in normal text in contrast to System 3, which extended the kernel by introducing persistent objects. Both extensions include a large set of user interface elements. Mastering the Oberon user interface, both the purely textual and the so-called Gadgets System (under S3), is non-trivial. Thus, after successfully installing Oberon System 3, it is recommended to study André Fischers Oberon System 3 Tutorial. An expanded version of this tutorial was published as a book, which it is out of print now. The whole book is available in electronic form under a one user license in every installed version of System 3 (Windows, Linux, or Native, i.e., also with the Gadgets toolkit of OLR). More information how to get your own copy of the Oberon Companion may be found in the Getting Started section of the Oberon Wikibook. Similar user Interfaces have yet to appear in more commonplace operating systems. Rob Pike's Acme system for Plan 9 from Bell Labs was strongly inspired by the Oberon TUI. Whether the worksheet interface of the Macintosh Programmer's Workshop influenced Oberon's TUI or vice versa is difficult to decide: the Oberon System was based on Wirth's prior computer design the Lilith, and both the Apple Macintosh (and its precursor Lisa) and the Oberon System (on Ceres and its precursor Lilith) have the same roots: they were all inspired by the Alto developed at Xerox PARC. Versions and availability V1 was the first usable version some time before the Oberon Trilogy was published. A major change in the text model together with the editor named Write yielded V2. As foreshadowed in the table in section History above, there was a major fork in the early 1990s: V4 vs. System 3: The group around Jürg Gutknecht introduced persistent objects and object-libraries thereby extending the kernel. The group around Hanspeter Mössenböck realized similar features by introducing active elements mapped to a special character thereby extending fonts without changing the kernel. System 3 was sometimes also named Spirit of Oberon and later renamed ETH Oberon, whereas V4 was sometimes also named Linz Oberon. As of 2017, the Oberon OS is available for several hardware computing platforms, generally in no cost versions and from several sources, which is quite confusing. The Oberon OS is typically extremely compact. Even with an Oberon compiler, assorted utilities including a web browser, TCP/IP networking, and a GUI, the full package can be compressed to one 3.5" floppy disk. There are versions which emulated the Oberon OS on another operating system and versions which run on bare hardware. The latter ones are named Native Oberon. There are native versions for the Ceres, Intel IA-32, and ARM platforms. In 2013, Niklaus Wirth adapted the basic system as described in "Project Oberon" to a current FPGA design. According to the preface of the 2013 edition, the whole system compiles in less than 10 seconds on a Spartan-3 board. This version is sometimes also named V5, despite it being much more similar functionally to the original V1 running on the Ceres than any of the later versions. A version of the Oberon System 3, which is more integrated in the Microsoft Windows OS than other implementations was named Plugin Oberon. Plugin Oberon had support for OLE, Netscape Plugins, and the binary format named Oberon Module Interchange (OMI) or slim binaries, which allowed portable object code between Intel x86, Motorola 68K, and PowerPC architectures. Slim binaries were invented by Michael Franz in the early 1990s. They were motivated and opposed to the fat binaries invented by Apple during the transition from 68k to PowerPC architectures. OMI provided portable code based on a compressed version of the abstract syntax tree. The approach of a compressed abstract syntax tree for portable code representation is revived in the Java world for GraalVM and Truffle. The version named Oberon V4 (see also History) is closer to the original operating system developed by Wirth and Gutknecht. It was originally developed at ETHZ, but when H.P. Mössenböck went to Institut für Systemsoftware at Johannes-Kepler University in Linz (JKU), the development of V4 moved also. Thus, V4 is sometimes also called Linz-Oberon in contrast to ETH-Oberon. The most recent version of V4 and extensions are available at JKU. Oberon V4 appears to be orphaned, there are almost no changes since 2000. Another repository of V4 is Claudio Nieder's Oberon V4, which also shows difference between the different V4 implementations. Since 2013 this page moved to/is mirrored at SourceForge. V4 is closer to what would now be called an integrated development environment than an operating system of its own. There were many extensions written for V4, which are still available from the ftp server of SSW at JKU; some documentation can be found on their web-pages, more information is normally included in the packages and it is given in Oberon's special rich text format. Around 2010, the computer science department at ETH Zurich began exploring active objects and concurrency for operating systems, and has released an early version of a new language Active Oberon and a new operating system for it, first named Active Object System (AOS) in 2002, then due to trademark issues, renamed Bluebottle in 2005, then renamed A2 in 2008. It is available from ETH Zurich with most source via the Internet. Native versions (A2) run on bare hardware, and are currently possible for Intel IA-32 and x86-64 single- and multi-processor systems, and for the StrongARM CPU family. Versions for other operating systems are available on Windows (WinAos), Unix (UnixAos), Linux (LinuxAos), and macOS (DarwinAos). More detailed information about A2 is on the Russian Wikipedia pages about A2. As a part of an industrial research project the Native Systems Group of ETH Zurich has developed an application-specific operating system named stailaOS which is based on the latest version Oberon OS. It is intended for uses such as real-time analytics, high performance automated trading system (ATS), main memory based enterprise resource planning (ERP), etc. Native Oberon Native Oberon is an Oberon System that runs on bare hardware. PC-Native Oberon is a version that runs on IA-32 (x86-32) PC hardware. There has never been a V4 Native Oberon, so all information in this section implicitly assumes that it is System 3. Native Oberon has small hardware requirements: 133 MHz Pentium, 100MB hard disk, VESA 2 graphics card with resolution minimum of 1024x768 pixels, optional 3Com network card. The basic system runs from one HD floppy disk, and more software can be installed through a network. The full installation includes the Gadgets GUI. It is written fully in the language Oberon. A version named Linux Native Oberon (LNO) uses Linux as a hardware abstraction layer (HAL). Its goal is to be as compatible as possible to PC-Native Oberon. Other versions of the Oberon System, without Native in the name, had partly modified interfaces of low level modules. In 2015, Peter Matthias revitalized LNO under the name Oberon Linux Revival (OLR) as a multi-platform distribution running seamlessly on Intel x86, ARM, MIPS, and RISC-V. It runs well on the Raspberry Pi and on the low cost CHIP computer; with some tweaking (adjusting group membership or/and permissions on some devices) it runs well on Tiny Core Linux. OLR interfaces with Linux kernel by direct system calls. , OLR lacks a network layer. Project Oberon 2013 In 2013, Wirth and Paul Reed completed a re-implementation of the original Oberon System for the Digilent Xilinx Spartan 3 FPGA Starter Board. The work includes a revision of "Project Oberon", identified as Project Oberon (New Edition 2013). In 2015, Reed collaborated with Victor Yurkovsky to create OberonStation, a Xilinx Spartan 3-based computer designed specifically to run Oberon. The system has since been ported to a Xilinx Spartan 6 FPGA Pepino development board by Saanlima Electronics, and a Xilinx Artix 7-based Digilent Nexys A7-100 FPGA Trainer board by CFB Software. Peter de Wachter implemented an emulator for it, which was also ported to Java and JavaScript by Michael Schierl, running in modern browsers, and ported to Free Pascal/Ultibo by Markus Greim and to Go. Andreas Pirklbauer maintains an experimental version and extensions of Project Oberon 2013 at GitHub. Gallery Glossary A2 – Formerly Active Object System (AOS) in 2002, renamed Bluebottle in 2005 due to rumored copyright issues, renamed A2 in 2008. ALO – ARM Linux Oberon; in LNO family and for ARM CPU. AOS – see A2 entry above. BB – BlackBox Component Builder. Component Pascal IDE from Oberon Microsystems. Bluebottle – see A2 entry above. CP – Component Pascal. A dialect in the Oberon family most similar to Oberon-2. ETHO – Oberon as developed at Swiss Federal Institute of Technology in Zurich: Eidgenössische Technische Hochschule (ETH). Fox – The compiler for Active Oberon, appearing in AOS (see A2 entry above). LEO – Linux ETH Oberon. ETHO 2.4.3 for Linux x86. LNO – Linux Native Oberon. NO – Native Oberon. Runs on bare hardware rather than on another operating system. OLR – Oberon Linux Revival. A version of NO which uses Linux as a HAL and runs on x86, ARM, and MIPS. OP2 – The Portable Oberon-2 Compiler. OP2 was developed to port Oberon onto commercially available platforms. PACO – (scope) PArallel COmpiler. Appears in A2 (see entry above). Compiles each scope in an independent thread. RISC5 – the central processing unit (CPU) of Project Oberon 2013 based on Wirth's RISC architecture. Not to be confused with RISC-V. UnixAOS – Unix-based AOS, see A2 entry above. WinAOS – Windows-based AOS, see A2 entry above. See also A2 (operating system) Oberon (programming language) Oberon-2 programming language References External links , old ETH Oberon homepage, dead since Jan-2020, redirect to Archive.org: archived version Oberon article on WikiWikiWeb Genealogy and History of the Oberon System version at archive.org Oberon Bibliography Oberon compilers. Install ETH Oberon using QEMU BlueBottle/AOS/A2 An evolution of Native Oberon with support for Multiprocessor systems with Active Objects (kind of threads running on separate processors, if available) and a zooming user interface available at ETH Zurich's redmine instance. Native Oberon Home Page redirected to Archive.org (May 2016 - this site has broken URLs in the links to the ftp-Server; files were moved from ftp://ftp.inf.ethz.ch/pub/ETHOberon/ to ftp://ftp.ethoberon.ethz.ch/) Native Oberon Hardware Compatibility redirected to archive.org ETH PC Native Oberon, Usage Notes Lukas Mathis' Blog about Oberon A nice trace back to the history of user interfaces and Oberon. Oberon V4 main page at Johannes Kepler University Linz Oberon V4 Sources Collected sources for different V4 implementations at SourceForge and Oberon V4 for Linux, more information in the corresponding wiki. http://www.projectoberon.com/, Project Oberon. Experimental Oberon WinOberon aka Plugin Oberon Version 2.6 as provided by Emil Zeller to Alexander Illjin around 2010 Oberon System 3 Tutorial by André Fischer (1997), archived version Free software operating systems Object-oriented operating systems 1987 software

Operating System (OS)

Minix Minix (from mini-Unix) is a Unix-like operating system based on a microkernel architecture. Since version 2.0, it has been Portable Operating System Interface (POSIX) compliant. Early versions of MINIX were created by Andrew S. Tanenbaum for educational purposes. Starting with MINIX 3, the primary aim of development shifted from education to the creation of a highly reliable and self-healing microkernel OS. MINIX is now developed as open-source software. MINIX was first released in 1987, with its complete source code made available to universities for study in courses and research. It has been free and open-source software since it was relicensed under the BSD-3-Clause license in April 2000. Implementation Minix 1.0 Andrew S. Tanenbaum created MINIX at Vrije Universiteit in Amsterdam to exemplify the principles conveyed in his textbook, Operating Systems: Design and Implementation (1987). An abridged 12,000 lines of the C source code of the kernel, memory manager, and file system of MINIX 1.0 are printed in the book. Prentice-Hall also released MINIX source code and binaries on floppy disk with a reference manual. MINIX 1 was system-call compatible with Seventh Edition Unix. Tanenbaum originally developed MINIX for compatibility with the IBM PC and IBM PC/AT 8088 microcomputers available at the time. Minix 1.5 MINIX 1.5, released in 1991, included support for MicroChannel IBM PS/2 systems and was also ported to the Motorola 68000 and SPARC architectures, supporting the Atari ST, Commodore Amiga, Apple Macintosh and Sun SPARCstation computer platforms. There were also unofficial ports to Intel 386 PC compatibles (in 32-bit protected mode), National Semiconductor NS32532, ARM and Inmos transputer processors. Meiko Scientific used an early version of MINIX as the basis for the MeikOS operating system for its transputer-based Computing Surface parallel computers. A version of MINIX running as a user process under SunOS and Solaris was also available, a simulator named SMX (operating system) or just SMX for short. Minix 2.0 Demand for the 68k-based architectures waned, however, and MINIX 2.0, released in 1997, was only available for the x86 and Solaris-hosted SPARC architectures. It was the subject of the second edition of Tanenbaum's textbook, cowritten with Albert Woodhull and was distributed on a CD-ROM included with the book. MINIX 2.0 added POSIX.1 compliance, support for 386 and later processors in 32-bit mode and replaced the Amoeba network protocols included in MINIX 1.5 with a TCP/IP stack. Version 2.0.3 was released in May 2001. It was the first version after MINIX had been relicensed under the BSD-3-Clause license, which was retroactively applied to all previous versions. Minix-vmd Minix-vmd is a variant of MINIX 2.0 for Intel IA-32-compatible processors, created by two Vrije Universiteit researchers, which adds virtual memory and support for the X Window System. Minix 3 Minix 3 was publicly announced on 24 October 2005 by Tanenbaum during his keynote speech at the Association for Computing Machinery (ACM) Symposium on Operating Systems Principles (SOSP). Although it still serves as an example for the new edition of Tanenbaum's textbook, coauthored by Albert S. Woodhull, it is comprehensively redesigned to be "usable as a serious system on resource-limited and embedded computers and for applications requiring high reliability." Minix 3 currently supports IA-32 and ARM architecture systems. It is available in a live CD format that allows it to be used on a computer without installing it on the hard drive, and in versions compatible with hardware emulating and virtualizing systems, including Bochs, QEMU, VMware Workstation and Fusion, VirtualBox, and Microsoft Virtual PC. Version 3.1.2 was released on 18 April 2006. It was the first version after MINIX had been relicensed under the BSD-3-Clause license with a new fourth clause. Version 3.1.5 was released on 5 November 2009. It contains X11, emacs, vi, cc, gcc, perl, python, ash, bash, zsh, ftp, ssh, telnet, pine, and over 400 other common Unix utility programs. With the addition of X11, this version marks the transition away from a text-only system. In many cases it can automatically restart a crashed driver without affecting running processes. In this way, MINIX is self-healing and can be used in applications demanding high reliability. MINIX 3 also has support for virtual memory management, making it suitable for desktop OS use. Desktop applications such as Firefox and OpenOffice.org are not yet available for MINIX 3 however. As of version 3.2.0, the userland was mostly replaced by that of NetBSD and support from pkgsrc became possible, increasing the available software applications that MINIX can use. Clang replaced the prior compiler (with GCC now having to be manually compiled), and GDB, the GNU debugger, was ported. Minix 3.3.0, released in September 2014, brought ARM support. Minix 3.4.0RC, Release Candidates became available in January 2016; however, a stable release of MINIX 3.4.0 is yet to be announced. Minix supports many programming languages, including C, C++, FORTRAN, Modula-2, Pascal, Perl, Python, and Tcl. Minix 3 still has an active development community with over 50 people attending MINIXCon 2016, a conference to discuss the history and future of MINIX. All Intel chipsets post-2015 are running MINIX 3 internally as the software component of the Intel Management Engine. Relationship with Linux Early influence Linus Torvalds used and appreciated Minix, but his design deviated from the Minix architecture in significant ways, most notably by employing a monolithic kernel instead of a microkernel. This was disapproved of by Tanenbaum in the Tanenbaum–Torvalds debate. Tanenbaum explained again his rationale for using a microkernel in May 2006. Early Linux kernel development was done on a Minix host system, which led to Linux inheriting various features from Minix, such as the Minix file system. Samizdat claims In May 2004, Kenneth Brown of the Alexis de Tocqueville Institution made the accusation that major parts of the Linux kernel had been copied from the MINIX codebase, in a book named Samizdat. These accusations were rebutted universally—most prominently by Tanenbaum, who strongly criticised Brown and published a long rebuttal on his own personal Web site, also claiming that Brown was funded by Microsoft. Licensing At the time of MINIX's original development, its license was relatively liberal. Its licensing fee was very small ($69) relative to those of other operating systems. Tanenbaum wished for MINIX to be as accessible as possible to students, but his publisher was unwilling to offer material (such as the source code) that could be copied freely, so a restrictive license requiring a nominal fee (included in the price of Tanenbaum's book) was applied as a compromise. This prevented the use of MINIX as the basis for a freely distributed software system. When free and open-source Unix-like operating systems such as Linux and 386BSD became available in the early 1990s, many volunteer software developers abandoned MINIX in favor of these. In April 2000, MINIX became free and open-source software under the BSD-3-Clause license, which was retroactively applied to all previous versions. However, by this time other operating systems had surpassed its capabilities, and it remained primarily an operating system for students and hobbyists. In late 2005, MINIX was relicensed with a fourth clause added to the BSD-3-Clause license. See also MINIX file system Minix-vmd MINIX 3 Redox —an operating system in Rust using a Minix-like kernel Xinu Notes References External links History of MINIX from Andrew Tanenbaum 1987 software Computer-related introductions in 1987 ARM operating systems Computer science in the Netherlands Dutch inventions Educational operating systems Free software operating systems Information technology in the Netherlands Lightweight Unix-like systems Microkernel-based operating systems Microkernels Operating system distributions bootable from read-only media Software using the BSD license Unix variants

Operating System (OS)

Open Software Foundation The Open Software Foundation (OSF) was a not-for-profit industry consortium for creating an open standard for an implementation of the operating system Unix. It was formed in 1988 and merged with X/Open in 1996, to become The Open Group. Despite the similarities in name, OSF was unrelated to the Free Software Foundation (FSF, also based in Cambridge, Massachusetts), or the Open Source Initiative (OSI). History The organization was first proposed by Armando Stettner of Digital Equipment Corporation (DEC) at an invitation-only meeting hosted by DEC for several Unix system vendors in January 1988 (called the "Hamilton Group", since the meeting was held at DEC's offices on Palo Alto's Hamilton Avenue). It was intended as an organization for joint development, mostly in response to a perceived threat of "merged UNIX system" efforts by AT&T Corporation and Sun Microsystems. After discussion during the meeting, the proposal was tabled so that members of the Hamilton Group could broach the idea of a joint development effort with Sun and AT&T. In the meantime, Stettner was asked to write an organization charter. That charter was formally presented to Apollo, HP, IBM and others after Sun and AT&T rejected the overture by the Hamilton Group members. The foundation's original sponsoring members were Apollo Computer, Groupe Bull, Digital Equipment Corporation, Hewlett-Packard, IBM, Nixdorf Computer, and Siemens AG, sometimes called the "Gang of Seven". Later sponsor members included Philips and Hitachi with the broader general membership growing to more than a hundred companies. It was registered under the U.S. National Cooperative Research Act of 1984, which reduces potential antitrust liabilities of research joint ventures and standards development organizations. The sponsors gave OSF significant funding, a broad mandate (the so-called "Seven Principles"), substantial independence, and support from sponsor senior management. Senior operating executives from the sponsoring companies served on OSF's initial Board of Directors. One of the Seven Principles was declaration of an "Open Process" whereby OSF staff would create Request for Proposals for source technologies to be selected by OSF, in a vendor neutral process. The selected technology would be licensed by the OSF to the public. Membership in the organization gave member companies a voice in the process for requirements. At the founding, five Open Process projects were named. The organization was seen as a response to the collaboration between AT&T and Sun on UNIX System V Release 4, and a fear that other vendors would be locked out of the standardization process. This led Scott McNealy of Sun to quip that "OSF" really stood for "Oppose Sun Forever". The competition between the opposing versions of Unix systems became known as the Unix wars. AT&T founded the Unix International (UI) project management organization later that year as a counter-response to the OSF. UI was led by Peter Cunningham, formerly of International Computers Limited (ICL), as its president. UI had many of the same characteristics of OSF, with the exception of a software development staff. Unix System Laboratories (USL) filled the software development role, and UI was based in Parsippany-Troy Hills, New Jersey to be close to USL. The executive staff of the Open Software Foundation included David Tory, President, formerly of Computer Associates; Norma Clarke, Vice-President Human Resources formerly of Mitre; Marty Ford, Vice-President Finance, formerly of DEC; Ira Goldstein, Vice-President Research Institute, formerly of Hewlett-Packard; Roger Gourd, Vice-President Engineering, formerly of DEC; Alex Morrow, Vice-President Strategy, formerly of IBM; Donal O'Shea, Vice-President of Operations, formerly of UniSoft. This staff added more than 300 employees in less than two years. The organization's headquarters were at 11 Cambridge Center in Cambridge, Massachusetts, intentionally located in the neighborhood of the Massachusetts Institute of Technology along with remote development offices in Munich, Germany and Grenoble, France and field offices in Brussels and Tokyo. To the public, the organization appeared to be nothing more than an advocacy group; in reality it included a distributed software development organization. An independent security software company - Addamax, filed suit in 1990 against OSF and its sponsors charging that OSF was engaged in anticompetitive practices. The court delivered a grant of summary judgment to OSF (152 F.3d 48, 50 (1st Cir.1998). In a related action in 1991, the Federal Trade Commission investigated OSF for allegedly using "unfair trade practices" in its "process for acquiring technology." Products OSF's Unix reference implementation was named OSF/1. It was first released in December 1990 and adopted by Digital a month later. As part of the founding of the organization, the AIX operating system was provided by IBM and was intended to be passed-through to the member companies of OSF. However, delays and portability concerns caused the OSF staff to cancel the original plan. Instead, a new Unix reference operating system using components from across the industry would be released on a wide range of platforms to demonstrate its portability and vendor neutrality. This new OS was produced in a little more than one year. It incorporated technology from Carnegie Mellon University: the Mach 2.5 microkernel; from IBM, the journaled file system and commands and libraries; from SecureWare secure core components; from Berkeley Software Distribution (BSD) the computer networking stack; and a new virtual memory management system invented at OSF. By the time OSF stopped development of OSF/1 in 1996, the only major Unix system vendor using the complete OSF/1 package was Digital (DEC), which rebranded it Digital UNIX (later renamed Tru64 UNIX after Digital's acquisition by Compaq). However, other Unix vendors licensed the operating system to include various components of OSF/1 in their products. Other software vendors also licensed OSF/1 including Apple. Parts of OSF/1 were contained in so many versions of Unix that it may have been the most widely deployed Unix product ever produced. Other technologies developed by OSF include Motif and Distributed Computing Environment (DCE), respectively a widget toolkit and package of distributed network computing technologies. The Motif toolkit was adopted as a formal standard within the Institute of Electrical and Electronics Engineers (IEEE) as P1295 in 1994. Filling out the initial (and what turned out to be final) five technologies from OSF were DME, the Distributed Management Environment and ANDF, the Architecturally Neutral Distribution Format. Technologies which were produced primarily by OSF included ODE, the Open Development Environment - a flexible development, build and source control environment; TET, the Test Environment Toolkit - an open framework for building and executing automated test cases; and the operating system OSF/1 MK from the OSF Research Institute based on the Mach3.0 microkernel. ODE and TET were made available as open source. TET was produced as a result of collaboration between OSF, UNIX International and the X/Open Consortium. All the OSF technologies had corresponding manuals and supporting publications produced almost exclusively by the staff at OSF and published by Prentice-Hall. IBM has published its version of ODE on GitHub. Merger By 1993, it had become clear that the greater threat to UNIX system vendors was not each other as much as the increasing presence of Microsoft in enterprise computing. In May, the Common Open Software Environment (COSE) initiative was announced by the major players in the UNIX world from both the UI and OSF camps: Hewlett-Packard, IBM, Sun, Unix System Laboratories, and the Santa Cruz Operation. As part of this agreement, Sun and AT&T became OSF sponsor members, OSF submitted Motif to the X/Open Consortium for certification and branding and Novell passed control and licensing of the UNIX trademark to the X/Open Consortium. In March 1994, OSF announced its new organizational model and introduced the COSE technology model as its Pre-Structured Technology (PST) process, which marked the end of OSF as a significant software development company. It also assumed responsibility for future work on the COSE initiative's Common Desktop Environment (CDE). In September 1995, the merger of OSF/Motif and CDE into a single project, CDE/Motif, was announced. In February 1996 OSF merged with X/Open to become The Open Group. References Free software project foundations in the United States Standards organizations in the United States Unix history Unix standards X Window System

Operating System (OS)

MAX (operating system) MaX is a Linux distribution sponsored by the Office of Education of the autonomous Community of Madrid of Spain. MaX stands for Madrid LinuX. It used to be based on Ubuntu. Its last release, MaX 10, is based on Ubuntu 16.04 LTS "Xenial Xerus". Since 2003 MaX has been installed on all the computers of the schools in the Community of Madrid. MaX is an educational Linux with a large set of instructive programs in addition to usual desktop programs. MaX supports the most common desktop environments but, in MaX 10, MATE is installed by default. Main features are simplicity, stability and a huge collection of software. MaX comes as a Live DVD and an installable system, and as a USB version. The changelog is here: http://ftp.rediris.es/mirror/MaX-Linux/MaXdesktop/MAX7.5/cambios.txt External links Homepage (in Spanish) Distrowatch page ISO images of MaX References EducaMadrid web site Educational operating systems Spanish-language Linux distributions State-sponsored Linux distributions Ubuntu derivatives Linux distributions

Operating System (OS)

X/Open X/Open Company, Ltd., originally the Open Group for Unix Systems, was a consortium founded by several European UNIX systems manufacturers in 1984 to identify and promote open standards in the field of information technology. More specifically, the original aim was to define a single specification for operating systems derived from UNIX, to increase the interoperability of applications and reduce the cost of porting software. Its original members were Bull, ICL, Siemens, Olivetti, and Nixdorf—a group sometimes referred to as BISON. Philips and Ericsson joined soon afterwards, at which point the name X/Open was adopted. The group published its specifications under the name X/Open Portability Guide (or XPG). Issue 1 covered basic operating system interfaces, and was published within a year of the group's formation. Issue 2 followed in 1987, and extended the coverage to include Internationalization, Terminal Interfaces, Inter-Process Communication, and the programming languages C, COBOL, FORTRAN, and Pascal, as well as data access interfaces for SQL and ISAM. In many cases these were profiles of existing international standards. XPG3 followed in 1988, its primary focus being convergence with the POSIX operating system specifications. This was probably the most widely used and influential deliverable of the X/Open organisation. By 1990 the group had expanded to 21 members: in addition to the original five, Philips and Nokia from Europe; AT&T Corporation, Digital, Unisys, Hewlett-Packard, IBM, NCR, Sun Microsystems, Prime Computer, Apollo Computer from North America; Fujitsu, Hitachi, and NEC from Japan; plus the Open Software Foundation and Unix International. X/Open managed the UNIX trademark from 1993 to 1996, when it merged with the Open Software Foundation to form The Open Group. X/Open was also responsible for the XA protocol for heterogeneous distributed transaction processing, which was released in 1991. Output The X/Open Portability Guide is a standard for UNIX systems originally published by X/Open Company Ltd. Based on the AT&T System V Interface Definition, it has a wider scope than POSIX, which is only concerned with direct operating system interfaces. The Portability Guide specifies a Common Application Environment (CAE) intended to allow portability of applications across operating systems. The primary aim was compatibility between different vendors' implementations of UNIX, though some vendors also implemented the standards on non-UNIX platforms. The XPG3 and XPG4 standards, released in 1989 and 1992 respectively, define all aspects of the operating system, programming languages and protocols which compliant systems should have. The last version of the XPG, the X/Open Portability Guide Issue 4 (also known as the Common Applications Environment Specification Issue 4 (CAE4)), was published in July 1992 by The Open Group. The Single UNIX Specification was based on the XPG4 standard. Chapters The XPG4 specification includes these chapters: System Interfaces and Headers (XSH), Issue 4, , C202 Commands and Utilities (XCU), Issue 4, , C203 System Interface Definitions (XBD), Issue 4, , C204 See also Joint Inter-Domain Management References - Mentions X/Open; lists members and its efforts to define "a new standard interface to UNIX". ICL and Europe, by Virgilio Pasquali, from RESURRECTION, The Bulletin of the Computer Conservation Society, Number 35, Summer 2005 - Contains more on history of X/Open C. B. Taylor. The X/OPEN group and the common application environment. ICL Technical Journal Vol 5(4) pp. 665–679, 1987. C. B. Taylor. X/Open - from Strength to Strength. ICL Technical Journal, Vol 7(3) pp. 565–583, 1991 C. B. Taylor. X/Open and Open Systems. X/Open Company Limited, 1992. External links The OpenGroup, formerly known as X/Open Company A History of Unix X/Open Portability Guide, issue 1, 1985 History of software Software engineering papers Standards organisations in the United Kingdom Technology consortia Unix history Unix standards

Operating System (OS)

MS-Net MS-Net, sometimes stylized as MS-NET, was an early network operating system sold by Microsoft during the earliest days of local area networking (LANs). Overview MS-Net was not a complete networking system of its own; Microsoft licensed it to vendors who used it as the basis for server programs that ran on MS-DOS, porting it to their own underlying networking hardware and adding services on top. Version 1.0 was announced on 14 August 1984 and released along with the PC/AT on 2 April 1985. A number of MS-Net products were sold during the late 1980s, before it was replaced by LAN Manager in 1990. MS-Net's network interface was based on IBM's NetBIOS protocol definition, which allowed it to be ported to different networking systems with relative ease. It did not implement the entire NetBIOS protocol, however, only the small number of features required for the server role. One key feature that was not implemented was NetBIOS's name management routines, a feature 3rd parties often added back in. The system also supplied the program REDIR.EXE, which allowed transparent file access from DOS machines to any MS-Net based server. Several products from the mid-to-late-1980s were based on the MS-Net system. IBM's PC-Net was a slightly modified version of the MS-Net system typically used with Token Ring. MS partnered with 3Com to produce the more widely used 3+Share system running on a 3Com networking stack based on the XNS protocol on Ethernet. Other well-known systems, including Banyan VINES and Novell NetWare, did not use MS-Net as their basis, using Unix and a custom OS, respectively. They did, however, allow access to their own files via the REDIR.EXE. MS-Net was sold only for a short period of time. MS and 3Com collaborated on a replacement known as LAN Manager running on OS/2, using the new Server Message Block standard for file transfer. 3Com's version of the product retained their XNS-based protocol, but 3Com abandoned the server market not long after. MS's version remained based on NetBIOS and supported a number of underlying protocols and hardware. LAN Manager was itself replaced in 1993 by Windows NT 3.1. See also Timeline of DOS operating systems net (command) References "IBM PC and PC-Compatible NOSs Compared", U-M Computing News, Volume 2 (1987), pp. 4–11. Discontinued Microsoft operating systems Network operating systems Proprietary operating systems Assembly language software 1985 software

Operating System (OS)

System Support Program System Support Program (SSP) was the operating system of the IBM System/34 and System/36 minicomputers. SSP was a command-based operating system released in 1977. History SSP originally contained 60 or so commands that were implemented on the System/34 from 1977 to 1983 in different versions called releases. Release 1 was issued with the original S/34 in 1977. Release 9 was issued in 1981. In 1983, IBM repackaged SSP on a new computer called the IBM System/36, which was not object-code compatible with the S/34. In 1994, IBM repackaged SSP on an updated model of the S/36 called the Advanced/36. The A/36 was an IBM AS/400 which had the SSP implemented as a "virtual machine". Major releases of SSP include: S/34 S/34 Release 1.0 – this was apparently shipped with the first S/34 in 1977. S/34 Release 8.0 – this seems to have been issued about 1980. S/34 Release 9.0 – this was the last release for the S/34 c.1980. S/36 S/36 Release 1.0 – this was apparently shipped with the first S/36 in 1983. S/36 Release 2.0 – this release supported the 8809 tape drive. S/36 Release 4.0 – this was the release where S/36 was given 5 job queues. S/36 Release 5.1 – this 1988 release was the last major change on 536X platforms. S/36 Release 6.0 – also known as the VASP or Value-Added Support Product, this release added functionality that allowed program calls in RPG, and it also provided software to calculate the size AS/400 that the user would need when upgrading. The VASP was controversial. Rumors circulated in the industry papers that the customer could not go back to 5.1 if 6.0 did not function adequately. Program calls with RPG CALL/PARM were inferior to RPGIII designs and inferior to customer add-on products. S/36 Release 7.1 – this 1994 release was shipped with the Advanced/36 (9402-236 models). The first A/36 machines would not function on a lower release and were also incompatible with 7.5 (while technically, true, program object code from a 7.1 machine would run on a 7.5 and vice versa, plus many 9402-236's were upgraded to 9402-436, which they changed out the motherboard and installed some new LIC code and you restored on a copy of your files and voila, it all worked). Rumors circulated that stated prior release compilers would not function on the Advanced/36, but they proved unfounded. There were reasons a programmer would rather use the 5.1 RPGII compiler instead of the presumably more advanced 7.x compiler. S/36 Release 7.5 – this 1995 release was shipped with the second and final wave of the Advanced/36 (9402-436). Functions like WRKSYSVL allowed the operator to change the system time on the fly, which was interesting because customer add-ons to do this through assembler subroutines did not function on the Advanced/36. However assembler routines to do things like open/close files, retrieve the VTOC, etc. functioned just fine on 7.1 and 7.5 Guest/36 – this is Release 7.5, but you could set up an M36 (a guest) on an AS/400 (running OS/400 V3R6 thru V4R4), and it would function just like the 9402-436, except that in addition to having this guest "partition", you also had OS/400 if you wanted it. So if the 9402-436 which came in 3 speeds 2102, 2104 and 2106 (which the latter was about 2.7X faster than the base) wasn't fast enough, you could get a 9406-xxx machine and install a "guest/36" on such. And actually you could install more than one guest/36. There was some limitations of number of attached workstations, but having two guest/36's running on an AS/400, and setting up DDM (distributed data management) between them and even with OS/400 to host large files, could easily be done. While the S/36 and A/36 for the most part worked only with twinax attached terminals, on a Guest/36 (or M/36), you could have all your terminals be on a LAN running tcp/ip and be virtual devices in the Guest/36 environment. S36EE (S/36 execution environment) – this was supported native on the AS/400 and its follow on (iSeries, IBM i), which allows a user to continue to run their s/36 programs and procedures without having to convert them. Many of the system procs also work with such. While it was typically "slower" since it has to go through additional steps, however today with such fast machines, the speed of an S36EE is many times faster than the A/36 execution speed. Example, one job took 12 minutes to run on an Adv/36, took 20 seconds to run in S36EE mode. The object code however is NOT compatible with the previous S/36 and A/36, meaning that one had to recompile all programs and menus. However one advantage is that you can not only run S36EE but also OS/400 applications. You can access database tables in your S/36 programs, you can call RPG/400 and RPGIV programs from with a S/36 program. So while technically not SSP, it looks like SSP, it acts like SSP and it will run your S/36 programs/procs. Limitations on S/36 and A/36 and M/36 operating system: The maximum amount of disk space that a system could utilize was 4 gb (per occurrence of the operating system, so a machine running two M36 "partitions" could have 4 gb in each. Another limitation was the program size, could not exceed 64KB. If you had a program that was larger than that, you had to become creative in the later years when call/parm came into place, as you would move code into a called program, because if the base program was 63kb for example, you could easily call a 20kb called program. You also could not have more than around 8,000+ files on the machine. There were also restrictions on the number of files you could bring into a program (again, you could get around by putting files in called programs and passing the result back in. The maximum number of records you could initially load was about 8 million and the maximum a file could hold was about 16 million. None of these limitations exist in S36EE (there are a few maximum number of files in a program, but much larger# than in native SSP). Functions and components Using SSP, the operator can create, delete, and manage S/34-36 objects such as libraries, data files, menus, procedures, source members, and security files. SSP contains modules such as DFU, SEU, SDA, and WSU that permit operators to build libraries and files, enter information into those files, produce simple reports, and maintain a menu structure that simplifies access to the information. The Advanced/36 does not support WSU. Password and resource security are also implemented through SSP, as are remote communications, which today is similar to dial-up networking. SSP is a disk-based operating system. Computer programs can be run from the fixed disk, but not from diskette or tape. The complement of a System/34 5340, or System/36 5360/5362 is a fixed disk array of one to four fixed disks, at least one computer terminal, and an 8" diskette drive, optionally fitted with two magazine units that can contain 10 diskettes each and three diskette slots.. A S/36 5363/5364 has a 5-1/4" diskette drive. S/36 computers can be configured with an 8809 reel-to-reel tape drive (800/1600 bpi) or a 6157 1/4" cartridge (QIC) tape drive. A/36 computers have a high-density QIC drive but the 5.25" or 8" diskette drive (single) was optional as was a 9348-001 9 track (reel to reel) 1600/6250 bpi tape drive. System utility programs SSP procedures utilize utility programs, which can in some cases be more useful to the computer programmer than the SSP procedures themselves. $MAINT is the library utility, used in ALOCLIBR, BLDLIBR, FROMLIBR, LIBRLIBR, REMOVE, CONDENSE, LISTLIBR, and TOLIBR. $COPY is the file utility used in SAVE, RESTORE, COPYDATA, and LISTDATA. There are many other utilities, including $FBLD, $LABEL, $DUPRD, $INIT, $DELET, $HIST, $CNFIG, #GSORT, $PACK, and $PROF, which are more flexible at the program level than associated SSP procedures can be. Configuring using CNFIGSSP The CNFIGSSP procedure was used to configure the system, including the devices. Each device is assigned a two-character ID. The first letter must be alphabetic; the second must be alphameric. The system also reserved certain IDs; the device can't be called I1 or F1, for example. I1 is the name of the diskette drive; F1 is what the system calls the hard drive (stands for "fixed disk," since it is not a removable disk pack.) To apply CNFIGSSP, the system must be dedicated (no other users logged on or programs running.) The system must be IPLed (rebooted.) When IPL finished, the new devices would appear on the status display. SDA - Screen Design Aid SDA allows the operator to build screen formats or menus. Command keys can be enabled/disabled. Input fields, output fields, and constants can be created and conditioned. Conditions (in RPG these are called indicators) can cause fields to disappear or change colours. SEU - Source Entry Utility SEU is a text editor which allows data entry on a line-by-line basis. Special forms are used to assist the operator in keying RPG programs or other types of form-based languages (WSU, Sort, SDA, etc.) SORT - The system sort utility SORT has one to eight input files, which may be of any valid record length. It has one output file, of any stated length, which may contain from zero to 8 million-plus records. A sort can contain entire records or just 3-byte addresses which point to records in an associated file. This was called an address-out file or ADDROUT. When using an Addrout, the program read in these 3-byte addresses and then fetched associated records from the master file. WSU - Work Station Utility This was an RPG-like language that ran on SSP. It was focused on data entry type programs. WSU was free, but it wasn't particularly well-received because it was so limited. DFU - Data File Utility It is an IBM-supplied no-charge item which is used to view and change field values in individual records. DFU can be used by programmers to update data base files on the fly without writing programs by programmers to create simple programs to do carry out basic operations on a data base file by data entry personnel to add or remove records from a file, or to print records. Programming Operational Control Language (OCL) High-level language programs require OCL to be activated. OCL is used to load programs into the system's memory and start them (a process called execution) and assign resources such as disk files, printers, message members, memory, and disk space to those programs. Other abilities, such as displaying text on the screen, pause messages, and so forth, make OCL more powerful. RPG II RPG II was modified from the System/3 days to allow access to the "WORKSTN file" to allow a punched card-based language to interact with a person sitting at a keyboard and monitor. A WORKSTN file was an output file (it wrote to the monitor) and also an input file (because it accepted the user's keyboard input). Thus it was labeled a combined-primary file or a combined-demand file. Command keys became RPG indicators KA-KY, and different on-screen forms were recognized by different invisible control characters hidden in the forms themselves. Since the user had to display a form on the screen in order to type, RPG II provided a way for a program to write output before accepting input. Many successful programmers moved from using the combined-primary WORKSTN file to using a combined-demand file, which had operation codes to read and write the display. There was even a way to code for multiple WORKSTNs; several people could sign on to the same copy of the same program in memory. The largest program size was 64k. Program attributes - MRTs, SRTs, NRTs and NEPs MRT = Multiple Requestor Terminal program. SSP could attach up to 7 terminals to a program at once. Any operator could start the program at their terminal, then other operators' terminals would be attached when they selected the same program. The maximum number of terminals to be serviced was controllable by the programmer. SRT = Single Requestor Terminal program. Not a MRT. NRT = No Requestor Terminal program. Started at a terminal, the NRT releases the requesting terminal and continues. This is similar to an MS-DOS TSR (Terminate and Stay Resident) program. By definition, any program that was EVOKEd or submitted to the JOBQ was a NRT. NEP = Never Ending Program. This was typically an interactive MRT program that would wait after all terminals disconnected until some terminal reconnected, avoiding initiation overhead. This was commonly used to allow large programs to be implemented as a chain of small programs that would pass the terminals from one to another while remaining ready to continue processing for other terminals and/or subsequent transactions. NRT programs could also be NEPs if written to loop and wait for some condition indicating there was work to be done. NEP programs normally did not end until system shutdown, unless written to recognize some special terminate condition. Object code formats Cobol, Fortran, and RPG generated object code (type O). Basic was interpreted only; a compilation utility called BASICS created subroutine code (type R). Basic programs could be saved as sources for compatibility with other computers, but the project's text was preserved in the subroutine (unless the programmer used the LOCK parameter to keep it private.) Procedures, which use OCL to start programs and assign resources to them, are type P. Source members for all objects are type S, with the exception of Basic as above-specified. DFU programs generated subroutine (R) code. So did WSU programs. Screen formats generated object code. Menus generated object code. A menu is simply a very specific screen format with a companion message member suffixed with two pound signs ("##") to contain the action to be taken when the associated number was chosen. Popular SSP applications The Programmer and Operator Productivity Aid (POP) was a widely used development program. It was included with the Advanced 36. MAPICS, the Manufacturing and Production Information Control System. IMAS, a simple accounting package BPCS, a more advanced accounting system IBM Office/36 collection of programs (DisplayWrite/36, IDDU, Query, and so forth) were popular in the late 1980s and were later bundled with the Advanced/36. The System/34 Text Editor was a precursor to Office/36. The Britz Word Processing System was a general-purpose text editor that had mailmerge, label, and basic file editing capabilities. System security There are four types of security on an SSP system: Badge security. Password security. Resource security. Menu security. Badge security is implemented using a stripe reader device attached to a 5250-series terminal. In order to log on, the user not only typed the user/password information but also swiped the badge through the reader. SECEDIT The SECEDIT procedure was used to work with User IDs and passwords. The user profile contains a 1-to-8 character alphanumeric User ID, a 4 character alphanumeric password, a code for the user's security rating – M (Master Security Officer), S (Security Officer), O (System Operator), C (Subconsole Operator), or D (Display Station Operator) – and a number of other default settings. The SECEDIT RESOURCE procedure was used to establish security ratings for file, library, folder, and group objects. Access levels of O (Owner), C (Change), U (Update), R (Read), E (Execute) or N (None) could be granted for a user to a particular resource. A group object was a sort of holding company that owned one or more lower objects. For example, granting access to the group ACCOUNTG made it easier to establish access to all of the accounting files. Group objects could also reference group files; the group UB referenced UB.OLD, UB.NEW, UB.01, or any filename with the embedded period. SECEDIT USERID was also used to confine a user's operational authority to a specific menu. By entering a Y for Mandatory Menu and specifying a default sign-on menu, the security officer could prevent the user from any program access not found on that sign-on menu. A user so confined could only run menu options, send messages, and sign off the system. Other procedures The PROF ("Profile") procedure was used to work with User IDs and passwords. The user profile contains a 1-to-8 character alphanumeric User ID, a 4 character alphanumeric password, a code for the user's security rating—M (Master Security Officer), S (Security Officer), O (System Operator), C (Subconsole Operator), or D (Display Station Operator) -- and a number of other default settings. The PRSRCID ("Profile Resource Security By User ID") procedure was used to establish security ratings for file and library objects. Access levels of O (Owner), G (Change), R (Read), E (Execute) or N (None) could be granted for a user to a particular resource. The printed disk catalog (VTOC, Volume Table of Contents) displayed all secured objects with the notation 3 as being secured. Files, libraries, and folders SSP provides for two different data objects called files and libraries. Files contain records, almost always with a fixed record length. Libraries contain programs which can reference and access these files. SSP contained more than 80 different commands that allowed operators to create, delete, copy, edit/change, and secure files and libraries. A library or a file must exist in a contiguous organization on one fixed disk (however, a library may contain one "extent" of roughly 50 blocks which must be reorganized, and it cannot be extended if allocated to other users). A file may be organized with an EXTEND value or it may be allocated with FILE OCL to automatically extend. All record adds/updates/deletes wait while the file is being extended. It is good sense policy to create extend values large enough to minimize the frequency of extends. Libraries could have "extents" that were not contiguous. At times, when compiling a program, an extent would be created and by doing a "CONDENSE", it was removed if there was enough room in the main allocation for it. Otherwise one did an ALOCLIBR to reallocate the library to a bigger size. Files on the S/36 may be Sequential (S), Direct (D), or Indexed (I). An indexed file can have multiple alternate indexes (X), and in fact, a sequential file may have alternate indexes placed on it so there is no primary index. An indexed file contains a key, which must be contiguous and may be up to 60 characters long; however, alternate indexes may have three-part keys which are not contiguous with one another. Duplicate keys in indexed or alternate index files may be allowed or disallowed. A file with direct organization is built with all records added and cannot auto-extend. A file with sequential or indexed organization is built with no records added. An alternate index always has as many records as its parent, as opposed to a System/38-style logical file which is built with conditions to filter records from the parent. In 1986, support for Distributed Data Management Architecture (DDM) was added to SSP. This enabled System/36 programs to create, manage, and access record-oriented files on remote System/36, System/38, and IBM mainframe systems running CICS. It also enabled programs on remote System/36 and System/38 computers to create, access, and manage files on a System/36. The initial record-oriented file models defined by DDM were based on the System/36 file system. Related operating systems The System/3 (1969) ran a disk-based batch operating system called the System Control Program (SCP) (5702-SC1). IBM later introduced an online program for the System/3 named the Communications Control Program (CCP) which was started as a batch program. The IBM System/32 (1975) ran a disk-based operating system also called the System Control Program. The IBM System/38 (1978) ran an operating system named the Control Program Facility (CPF) that was much more advanced than SSP and not particularly similar. Sources IBM Publication SC21-8299, General Information for SSP Operating System. External links Bitsavers Archive of System/34 Documentation - Including documentation on SSP Bitsavers Archive of System/36 Documentation - Including documentation on SSP Computer-related introductions in 1979 IBM operating systems

Operating System (OS)

OPS5 OPS5 is a rule-based or production system computer language, notable as the first such language to be used in a successful expert system, the R1/XCON system used to configure VAX computers. The OPS (said to be short for "Official Production System") family was developed in the late 1970s by Charles Forgy while at Carnegie Mellon University. Allen Newell's research group in artificial intelligence had been working on production systems for some time, but Forgy's implementation, based on his Rete algorithm, was especially efficient, sufficiently so that it was possible to scale up to larger problems involving hundreds or thousands of rules. OPS5 uses a forward chaining inference engine; programs execute by scanning "working memory elements" (which are vaguely object-like, with classes and attributes) looking for matches with the rules in "production memory". Rules have actions that may modify or remove the matched element, create new ones, perform side effects such as output, and so forth. Execution continues until no more matches can be found. In this sense, OPS5 is an execution engine for a Petri net extended with inhibitor arcs. The OPS5 forward chaining process makes it extremely parallelizeable during the matching phase, and several automatic parallelizing compilers were created. OPS4 was an early version, while OPS83 came later. The first implementation of OPS5 was written in Lisp, and later rewritten in BLISS for speed. DEC OPS5 is an extended implementation of the OPS5 language definition, developed for use with the OpenVMS, RISC ULTRIX, and DEC OSF/1 operating systems. References Charles Forgy, OPS5 User's Manual, Technical Report CMU-CS-81-135 (Carnegie Mellon University, 1981) Lee Brownston, Robert Farrell, Elaine Kant, Nancy Martin, Programming Expert Systems in OPS5 (Addison-Wesley, 1985) Anoop Gupta, Miland Tambe, Dirk Kalp, Charles Forgy, and Allen Newell, Parallel Implementation of OPS5 on the Encore Multiprocessor: Results and Analysis Rob Lewis, OPS5 Revisited (Amazon 2016) External links OPS5 overview OPS5 Reference manual RuleWorks - Open-sourced language based on OPS5, with added modularity constructs. OPS5: RETE-based expert system shell - CMU Artificial Intelligence Repository source code - OPS5 source code on GitHub Free OPS5 implementation in .Net Core Functional languages Common Lisp (programming language) software

Operating System (OS)

Windows 2.0x Windows 2.0 is a 16-bit Microsoft Windows GUI-based operating environment that was released on December 9, 1987, and the successor to Windows 1.0. This product's family includes Windows 2.0, a base edition for 8086 real mode, and Windows/386 2.0, an enhanced edition for i386 protected mode. On December 31, 2001, Microsoft declared Windows 2.0 obsolete and stopped providing support and updates for the system. Features Windows 2.0 allowed application windows to overlap each other, unlike its predecessor Windows 1.0, which could display only tiled windows. Windows 2.0 also introduced more sophisticated keyboard-shortcuts and the terminology of "Minimize" and "Maximize", as opposed to "Iconize" and "Zoom" in Windows 1.0. The basic window setup introduced here would last through Windows 3.1. New features in Windows 2.0 included support for the new capabilities of the i386 CPU in some versions , 256-color VGA graphics, and EMS memory support. It was also the last version of Windows that did not require a hard disk. With the improved speed, reliability and usability, computers now started becoming a part of daily life for some workers. Desktop icons and use of keyboard shortcuts helped to speed up work. The Windows 2.x EGA, VGA, and Tandy drivers notably provided a workaround in Windows 3.0 for users who wanted color graphics on 8086 machines (a feature that version normally did not support). IBM licensed Windows's GUI for OS/2 as Presentation Manager, and the two companies stated that it and Windows 2.0 would be almost identical. Editions Windows 2.0x came in two different variants with different names and CPU support. The first variant simply said "Windows" on the box, with a version number on the back distinguishing it from Windows 1.x. The second was billed on the box as "Windows/386" This distinction continued to Windows 2.1x, where the naming convention changed to Windows/286 and Windows/386 to clarify that they were different versions of the same product. Windows The basic edition only supports 8086 real mode. This edition would be renamed Windows/286 with the release of Windows 2.1x. Despite its name, Windows/286 remained fully operational on an 8088 or 8086 processor, although the high memory area would not be available on an 8086-class processor; however, expanded memory (EMS) could still be used, if present. A few PC vendors shipped Windows/286 with 8086 hardware; an example was IBM's PS/2 Model 25, which had an option to ship with a "DOS 4.00 and Windows kit" for educational markets, which included word processing and presentation software useful for students, which resulted in some confusion when purchasers of this system received a box labeled Windows/286 with an 8086-based computer. Windows/386 Windows/386 was available as early as September 1987, pre-dating the release of Windows 2.0 in December 1987. Windows/386 was much more advanced than its 286 sibling. It introduced a protected mode kernel, above which the GUI and applications run as a virtual 8086 mode task. Windows/386 had fully preemptive multitasking, and allowed several MS-DOS programs to run in parallel in "virtual 8086" CPU mode, rather than always suspending background applications. (Windows applications could already run in parallel through cooperative multitasking.) With the exception of a few kilobytes of overhead, each DOS application could use any available low memory before Windows was started. Windows/386 ran Windows applications in a single Virtual 8086 box, with EMS emulation. In contrast, Windows 3.0 in standard or enhanced mode ran Windows applications in 16 bits protected mode segments. Windows/386 also provided EMS emulation, using the memory management features of the i386 to make RAM beyond 640k behave like the banked memory previously only supplied by add-in cards and used by popular DOS applications. (By overwriting the WIN200.BIN file with COMMAND.COM, it is possible to use the EMS emulation in DOS without starting the Windows GUI.) There was no support for disk-based virtual memory, so multiple DOS programs had to fit inside the available physical memory; therefore, Microsoft suggested buying additional memory and cards if necessary. Neither of these versions worked with DOS memory managers like CEMM or QEMM or with DOS extenders, which have their own extended memory management and run in protected mode as well. This was remedied in version 3.0, which is compatible with Virtual Control Program Interface (VCPI) in "standard mode" and with DOS Protected Mode Interface (DPMI) in "386 enhanced" mode (all versions of Windows from 3.0 to 98 exploit a loophole in EMM386 to set up protected mode). Windows 3.0 also had the capability of using the DWEMM Direct Write Enhanced Memory Module. This is what enables the far faster and more sleek graphical user interface, as well as true extended memory support. BYTE in 1989 listed Windows/386 as among the "Distinction" winners of the BYTE Awards, describing it as "serious competition for OS/2" as it "taps into the power of the 80386". Application support The first Windows versions of Microsoft Word and Microsoft Excel ran on Windows 2.0. Third-party developer support for Windows increased substantially with this version (some shipped the Windows Runtime software with their applications, for customers who had not purchased the full version of Windows). However, most developers still maintained DOS versions of their applications, as Windows users were still a distinct minority of their market. Windows 2.0 was still very dependent on the DOS system and it still hadn't passed the 1 megabyte mark in terms of memory. Stewart Alsop II predicted in January 1988 that "Any transition to a graphical environment on IBM-style machines is bound to be maddeningly slow and driven strictly by market forces", because the GUI had "serious deficiencies" and users had to switch to DOS for many tasks. There were some applications that shipped with Windows 2.0. They are: CALC.EXE – a calculator CALENDAR.EXE – calendaring software CARDFILE.EXE – a personal information manager CLIPBRD.EXE – software for viewing the contents of the clipboard CLOCK.EXE – a clock CONTROL.EXE – the system utility responsible for configuring Windows 2.0 CVTPAINT.EXE - Converted paint files to the 2.x format MSDOS.EXE – a simple file manager NOTEPAD.EXE – a text editor PAINT.EXE – a raster graphics editor that allows users to paint and edit pictures interactively on the computer screen PIFEDIT.EXE – a program information file editor that defines how a DOS program should behave inside Windows REVERSI.EXE – a computer game of reversi SPOOLER.EXE – the print spooler of Windows, a program that manages and maintains a queue of documents to be printed, sending them to the printer as soon as the printer is ready TERMINAL.EXE – a terminal emulator WRITE.EXE – a simple word processor Legal conflict with Apple On March 17, 1988, Apple Inc. filed a lawsuit against Microsoft and Hewlett-Packard, accusing them of violating copyrights Apple held on the Macintosh System Software. Apple claimed the "look and feel" of the Macintosh operating system, taken as a whole, was protected by copyright and that Windows 2.0 violated this copyright by having the same icons. The judge ruled in favor of Hewlett-Packard and Microsoft on all but 10 of the 189 graphical user interface elements on which Apple sued, and the court found the remaining 10 GUI elements could not be copyrighted. Windows 2.1x The successor to Windows 2.0, called Windows 2.1x was officially released in the United States and Canada on May 27, 1988. The final entry in the 2.x series, Windows 2.11, was released in March 1989. See also DESQview 386 VM/386 References External links GUIdebook: Windows 2.0 Gallery – A website dedicated to preserving and showcasing Graphical User Interfaces ComputerHope.com: Microsoft Windows history Microsoft article with details about the different versions of Windows 1987 software Products and services discontinued in 2001 2.0x History of Microsoft History of software Products introduced in 1987

Operating System (OS)

History of RISC OS RISC OS, the computer operating system developed by Acorn Computers for their ARM-based Acorn Archimedes range, was originally released in 1987 as , soon followed by , and . The next version, , became and was completed and made available in April 1989. was released with the very earliest version of the A5000 in 1991 and contained a series of new features. By 1996 RISC OS had been shipped on over 500,000 systems. was released by RISCOS Ltd (ROL) in July 1999, based on the continued development of . ROL had in March 1999 licensed the rights to RISC OS from Element 14 (the renamed Acorn) and eventually from the new owner, Pace Micro Technology. According to the company, over 6,400 copies of on ROM were sold up until production was ceased in mid-2005. was launched in May 2001 by ROL. This is a subscription scheme allowing users access to the latest OS 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. was shipped in May 2002, with following in November 2002 and the final release of in June 2004. ROL released the ROM based the same month, dubbed as a play on the RISC OS GUI convention of calling the three mouse buttons 'Select', 'Menu' and 'Adjust'. ROL sold its 500th Adjust ROM in early 2006. was released in October 2002 on Castle Technology's Acorn clone Iyonix PC. is a separate evolution based upon the NCOS work done by Pace for set-top boxes. In October 2006, Castle announced a source sharing license plan for elements of . This Shared Source Initiative (SSI) is managed by RISC OS Open Ltd (ROOL). RISC OS 5 has since been released under a fully free and open source Apache 2.0 license, while the older no longer maintained RISC OS 6 older has not. was also announced in October 2006 by ROL. This is the next generation of their stream of the operating system. The first product to be launched under the name was the continuation of the Select scheme, . A beta-version of , (), was available in 2007 as a free download to all subscribers to the Select scheme, while in April 2009 the final release of was shipped. The latest release of RISC OS from ROL is , shipped in December 2009. Arthur The OS was designed in the United Kingdom by Acorn for the 32-bit ARM based Acorn Archimedes, and released in its first version in 1987, as the Arthur operating system. The first public release of the OS was Arthur 1.20 in June 1987. It was bundled with a desktop graphical user interface (GUI), which mostly comprises assembly language software modules, and the Desktop module itself being written in . It features a colour-scheme typically described as "technicolour". The graphical desktop runs on top of a command-line driven operating system which owes much to Acorn's earlier MOS operating system for its BBC Micro range of 8-bit microcomputers. Arthur, as originally conceived, was intended to deliver similar functionality to the operating system for the BBC Master series of computers, MOS, as a reaction to the fact that a more advanced operating system research project (ARX) would not be ready in time for the Archimedes. The Arthur project team, led by Paul Fellows, was given just five months to develop it entirely from the ground up—with the directive "just make it like the BBC micro". It was intended as a stop-gap until the operating system which Acorn had under development (ARX) could be completed. However, the latter was delayed time and again, and was eventually dropped when it became apparent that the Arthur development could be extended to have a window manager and full desktop environment. Also, it was small enough to run on the first 512K machines with only a floppy disc, whereas ARX required 4 megabytes and a hard drive. The OS development was carried out using a prototype ARM-based system connected to a BBC computer, before moving onto the prototype Acorn Archimedes the A500. Arthur was not a multitasking operating system, but offered support for adding application-level cooperative multitasking. No other version of the operating system was released externally, but internally the development of the desktop and window management continued, with the addition of a cooperative multitasking system, implemented by Neil Raine, which used the memory management hardware to swap-out one task, and bring in another between call-and-return from the Wimp_Poll call that applications were obliged to make to get messages under the desktop. Reminiscent of a similar technique employed by MultiFinder on the Apple Macintosh, this transformed a single-application-at-a-time system into one that could operate a full multi-tasking desktop. This transformation took place at version 1.6 though it was not made public until released, with the name change from Arthur to RISC OS, as version 2.0. Most software made for Arthur 1.2 can be run under RISC OS 2 and later because, underneath the desktop, the original Arthur OS core, API interfaces and modular structures remain as the heart of all versions. (A few titles will not work, however, because they used undocumented features, side effects or in a few cases APIs that became deprecated). In 2011, Business Insider listed Arthur as one of ten "operating systems that time forgot". RISC OS 2 RISC OS was a rapid development of Arthur 1.2 after the failure of the ARX project. Given growing dissatisfaction with various bugs and limitations with Arthur, testing of what was then known as was apparently ongoing during 1988 with selected software houses. At this stage, Computer Concepts, who had been prolific developers for the BBC Micro and who had begun software development for the Archimedes, had already initiated a rival operating system project, Impulse, to support their own applications (including the desktop publishing application that would eventually become Impression), stating that Arthur did not meet the "hundreds of requirements" involved including "true multi-tasking". Such an operating system was to be offered free of charge with the planned application packages, but with the release of RISC OS and Computer Concepts acknowledging that RISC OS "overcomes the old problems with Arthur", the applications were to be able to run under either RISC OS or Impulse. Impression was eventually released as a RISC OS application. Ultimately, was renamed to RISC OS, and was first sold as RISC OS 2.00 in April 1989. The operating system implements co-operative multitasking with some limitations but is not multi-threaded. It uses the ADFS file system for both floppy and hard disc access. It ran from a 512 KB set of ROMs. The WIMP interface offers all the standard features and fixes many of the bugs that had hindered Arthur. It lacks virtual memory and extensive memory protection (applications are protected from each other, but many functions have to be implemented as 'modules' which have full access to the memory). At the time of release, the main advantage of the OS was its ROM; it booted very quickly and while it was easy to crash, it was impossible to permanently break the OS from software. Its high performance was due to much of the system being written in ARM assembly language. The OS was designed with users in mind, rather than OS designers. It is organised as a relatively small kernel which defines a standard software interface to which extension modules are required to conform. Much of the system's functionality is implemented in modules coded in the ROM, though these can be supplanted by more evolved versions loaded into RAM. Among the kernel facilities are a general mechanism, named the callback handler, which allows a supervisor module to perform process multiplexing. This facility is used by a module forming part of the standard editor program to provide a terminal emulator window for console applications. The same approach made it possible for advanced users to implement modules giving RISC OS the ability to do pre-emptive multitasking. A slightly updated version, RISC OS 2.01, was released later to support the ARM3 processor, larger memory capacities, and the VGA and SVGA modes provided by the Acorn Archimedes 540 and Acorn R225/R260. RISC OS 3 introduced a number of new features, including multitasking Filer operations, applications and fonts in ROM, no limit on number of open windows, ability to move windows off screen, safe shutdown, the Pinboard, grouping of icon bar icons, up to 128 tasks, native ability to read MS-DOS format discs and use named hard discs. Improved configuration was also included, by way of multiple windows to change the settings. RISC OS 3.00 was released with the very earliest version of the A5000 in 1991; it is almost four times the size of RISC OS 2 and runs from a 2 MB ROM. It improves multitasking and also places some of the more popular base applications in the ROM. RISC OS 3.00 had several bugs and was replaced by RISC OS 3.1 a few months later; the upgraded ROMs were supplied for the cost of postage. RISC OS 3.1 was released later and sold built into the A3010, A3020, A4000, A4 and later A5000 models. It was also made available as replacement ROMs for the A5000 and earlier Archimedes machines (this is the last RISC OS version suitable for those machines). Three variants were released: RISC OS 3.10 the base version, RISC OS 3.11 which included a slight update that fixes some serial port issues and RISC OS 3.19 which was a German translation. RISC OS 3.50 was sold from 1994 with the first Risc PCs. Due to the very different hardware architecture of the Risc PC, including an ARM 6 processor, 16- and 24-bit colour and a different IO chip (IOMD), RISC OS 3.50 was not made available for the older Archimedes and A Series ARM2 and 3 machines. RISC OS 3.5 was somewhat shoehorned into the 2 MB footprint, and moved the ROM applications of RISC OS 3.1 onto the hard drive; this proved so unpopular that they were later moved back into ROM. This version introduced issues of backward compatibility, particularly with games. RISC OS 3.60 followed in 1995. The OS features much improved hard disk access and its networking was enhanced to include TCP/IP as standard in addition to Acorn's existing proprietary Econet system. The hardware support was also improved; Risc PCs could now use ARM7 processors. Acorn's A7000 machine with its ARM7500 processor was also supported. RISC OS 3.6 was twice the size of RISC OS 3.5, shipping on 4 MB in two ROM chips; components that had been moved onto disk in 3.5 (the standard application suite and networking) were now moved back into ROM. RISC OS 3.70 was released in 1996. The primary changes in the OS was support for the StrongARM processor that was made available as an upgrade for the Risc PC. This required extensive code changes due to StrongARM's split data and instruction cache (Harvard architecture) and 32-bit interrupt modes. RISC OS 3.71 is a small update released to support the hardware in the Acorn A7000+ with its ARM7500FE processor. The FE offered hardware support for floating point mathematics, which until then was usually emulated in one of the RISC OS Software modules). RISC OS 3.60 also formed the foundation of NCOS, as shipped in the Acorn NetChannel NCs. Demise of Acorn Computers Ltd Acorn officially halted work in all areas except set-top boxes in January 1999 and the company was renamed Element 14 (the 14th element of the periodic table being silicon) with a new goal to become purely a Silicon design business (like the previous very successful spin off of ARM from Acorn in 1990). RISC OS development was halted during the development of OS 4.0 for the RiscPC 2 ("Phoebe 2100"), whose completion was also cancelled. A beta version, OS 3.8 ("Ursula") for the original RiscPC, had previously been released to developers. The project code names of Phoebe (for the hardware), Ursula (for the software) and Chandler (for the graphics processor chip) were taken from the names of characters in the TV series Friends (Phoebe and Ursula were twin sisters in the series). This led to a number of rescue efforts to try to keep the Acorn desktop computer business alive. Acorn held discussions with many interested parties, and eventually agreed to exclusively licence RISC OS to RISCOS Ltd, which was formed from a consortium of dealers, developers and end-users. Pace purchased the rights to use and develop NCOS. There were also a number of projects to bring the advantages of the RISC Operating System to other platforms by the creation of the ROX Desktop to provide a RISC OS-like interface on Unix and Linux systems. The separate work by and Pace resulted in a code fork. This continued after the subsequent licensing agreement with Castle Technology, causing much community debate at the time. The debate remains ongoing in 2011. Work post-Acorn by RISCOS Ltd RISC OS 4 In March 1999, a new company called RISCOS Ltd was founded. They licensed the rights to RISC OS from Element 14 (and eventually from the new owner, Pace Micro Technology) and continued the development of OS 3.8, releasing it as RISC OS 4 in July 1999. Whilst the hardware support for Phoebe was not needed, the core improvements to RISC OS 3.80 could be finished and released. They included: a better file system, increasing the number of items in directory from 77 to approximately 88,000 and increasing the max length of a filename from 10 characters to 255 a plugin based system configuration utility a new screensaver API an enhanced window manager an updated interactive help application a redesigned set of icons According to the company, over 6,400 copies of RISC OS 4.02 on ROM were sold up until production was ceased in mid-2005. During 1999 and 2000, RISCOS Ltd also released versions of RISC OS 4 to support several additional hardware platforms, the MicroDigital Mico, MicroDigital Omega, RiscStation R7500 and the Castle Kinetic RiscPC. In 2003 a version of RISC OS 4 was released with support for the Millipede Graphics AlphaLock podule. RISC OS 4 is also available for various hardware emulators for other operating systems. In September 2003 VirtualAcorn released the commercial emulator VirtualRPC which included a copy of RISC OS 4.02. In December 2008 RISCOS Ltd made 4.02 available for non-commercial emulators for £5 in a product called Virtually Free. RISC OS Select and Adjust In May 2001, the company launched RISC OS Select, a subscription scheme allowing users access to the latest OS 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. By providing soft-loads, physical ROM costs are eliminated and updates are able to be delivered with accelerated speed and frequency. It has also allowed the company to subsidise the retail price of ROM releases, which are generally a culmination of the last few Select upgrades with a few extra minor changes. In May 2002 the final release of Select 1 was shipped that included; DHCP client Multi-User support and logon Preview versions of new printer support and networking with AppleTalk In November 2002, the final release of Select 2 was shipped that included; Support for CMYK sprites Hardware support for the scroll wheel on PS/2 mice Support for the window manager tools to be in a configurable order RiscStation hardware support is now in the kernel In June 2004 the final release of Select 3 was shipped that included: Cut and Paste supported in writeable icons (textboxes) The filer can display image thumbnails Button and other icons can now support rounded borders The sprite format now supported an alpha channel A recycle bin An improved version of !Paint, the bitmap editor, to support the alpha channel sprites Also in June 2004, RISCOS Ltd released the ROM based version 4.39, being dubbed RISC OS Adjust. (The name was a play on the RISC OS GUI convention of calling the three mouse buttons 'Select', 'Menu' and 'Adjust'.) RISCOS Ltd sold its 500th Adjust ROM in early 2006. Features introduced in 4.39 include user customization of the graphical user interface. Further release under the Select scheme were made under the RISC OS Six branding, mentioned below. The A9Home The A9home, released in 2006, uses version 4.42 Adjust 32. This was developed by and supports 32-bit addressing modes found on later ARM architectures. RISC OS Six In October 2006, shortly after Castle Technology announced the Shared Source Initiative, RISCOS Ltd announced RISC OS Six, the next generation of their stream of the operating system. The first product to be launched under the RISC OS Six name, was the continuation of the Select scheme, Select 4. A beta-version of RISC OS 6, Preview 1 (Select 4i1), was available in 2007 as a free download to all subscribers to the Select scheme, both present subscribers and those whose subscription was renewed after 30 May 2004 but has since lapsed. RISC OS Six brought portability, stability and internal structure improvements, including full 26/32-bit neutrality. It is now highly modularised, with legacy and hardware specific features abstracted, and other code separated for easier future maintenance and development. Teletext support, device interrupt handler, software-based graphics operations, the real-time clock, the mouse pointer, CMOS RAM support, and hardware timer support have been abstracted out of the kernel and into their own separate modules. Legacy components, like the VIDC driver, and obsolete functionality for the BBC Micro have been abstracted too. AIF and transient utility executable checking has been introduced also to protect against rogue software, while graphics acceleration modules may be provided for the SM501 graphics chip in the A9home and for ViewFinder AGP podule cards. In April 2008 the final release of Select 4 was shipped that included: 8 MB VRAM support in VirtualRPC Filer updates, Keyboard shortcuts, alternative layouts, configurability SVG export in !Draw Select 4 releases are initially compatible with only Acorn Risc PC and A7000 machines. RiscStation R7500, MicroDigital Omega and Mico computers will not officially be supported, as the company does not have test machines available and requires proprietary software code to which they do not have the rights. Lack of detailed technical information about the MicroDigital Omega has also been cited as being another reason why support of that hardware is difficult. In April 2009 the final release of Select 5 was shipped that included: 64K colour screen modes More responsive desktop Improvements to !Paint and !Draw The final release of RISC OS from RISCOS Ltd was Select 6i1, shipped in December 2009, it includes; Configurable Filer toolbars Improved Task Manager Improved Draw with new editing features Configurable File Types menu New Firewall configuration interface Improvements to Pinboard configuration Improvements to Configure itself Post-Acorn development RISC OS 5 RISC OS 5 is a separate evolution by Castle Technology Ltd based upon work done by Pace for their NCOS based set top boxes. RISC OS 5 was written to support Castle's Iyonix PC Acorn-compatible, which runs on the Intel XScale ARM processor. Although a wealth of software has now been updated, a few older applications can only be run on RISC OS 5 via an emulator called Aemulor, since the ARMv5 XScale processor does not support 26-bit addressing modes. Likewise, RISC OS 5 itself had to be ported to run properly on the new CPU, and abstraction of the graphics and other hardware interfaces created, to allow it, for example, to use standard graphics cards, instead of Acorn's own VIDC chip. In July 2003, Castle Technology Ltd bought the head licence for RISC OS from Pace Micro. Shared Source Initiative In October 2006, Castle Technology Ltd announced a plan to release elements of RISC OS 5 under a source sharing license. The Shared Source Initiative (SSI) was a joint venture between Castle and RISC OS Open Limited (ROOL), a newly formed software development company, which aimed to accelerate development and encourage uptake of the OS. Under the custom dual license, released source was freely available and could be modified and redistributed without royalty for non-commercial use, while commercial usage incurred a per-unit license fee to Castle. The SSI made phased releases of source code, starting in May 2007. By October 2008, enough source was released to build an almost complete Iyonix ROM image. By late 2011, it was possible to build complete ROM images from the published sources; with the full source code available as tarballs, CVS, or a web interface to the CVS archive. In October 2018, the rights to RISC OS 5 were acquired by RISC OS Developments, and re-licensed under the Apache 2.0 license. ROOL continues to maintain the source tree and co-ordinates an international developer community on a non-profit basis to support and encourage development. Prebuilt images are available, as both stable releases and development "nightly builds". Ports of RISC OS 5 are available for the A7000/A7000+, RiscPC, RPCemu, the OMAP3 BeagleBoard and derivatives, OMAP4 PandaBoard and PandaBoard ES, AM5728 Titanium, the Raspberry Pi, and the XScale Iyonix. References External links Archiology: Michael Gilbert's collection of "relics from Acorn's past" Arthur Lives!: a guide by Ben Jefferys Arthur OS Emulator What is RISC OS? Pink Noise Productions OS documentation Acorn operating systems History of software

Operating System (OS)

Copland (operating system) Copland is an operating system developed by Apple for Macintosh computers between 1994 and 1996 but never commercially released. It was intended to be released as System 8, and later, Mac OS 8. Planned as a modern successor to the aging System 7, Copland introduced protected memory, preemptive multitasking, and several new underlying operating system features, while retaining compatibility with existing Mac applications. Copland's tentatively planned successor, codenamed Gershwin, was intended to add more advanced features such as application-level multithreading. Development officially began in March 1994. Over the next several years, previews of Copland garnered much press, introducing the Mac audience to basic concepts of modern operating system design such as object orientation, crash-proofing, and multitasking. In May 1996, Gil Amelio stated that Copland was the primary focus of the company, aiming for a late-year release. Internally, however, the development effort was beset with problems due to dysfunctional corporate personnel and project management. Development milestones and developer release dates were missed repeatedly. Ellen Hancock was hired to get the project back on track, but quickly concluded it would never ship. In August 1996, it was announced that Copland was canceled and Apple would look outside the company for a new operating system. Among many choices, they selected NeXTSTEP and purchased NeXT in 1997 to obtain it. In the interim period, while NeXTSTEP was ported to the Mac, Apple released a much more legacy-oriented Mac OS 8 in 1997, followed by Mac OS 9 in 1999. Mac OS X became Apple's next-generation operating system with its release in 2001. All of these releases bear functional or cosmetic influence from Copland. The Copland development effort can be described by pejorative software industry terminology such as "empire building," feature creep, and project death march. In 2008, PC World included Copland on a list of the biggest project failures in information technology (IT) history. Design Mac OS legacy The prehistory of Copland begins with an understanding of the Mac OS legacy, and its architectural problems to be solved. Launched in 1984, the Macintosh and its operating system were designed from the start as a single-user, single-tasking system, which allowed the hardware development to be greatly simplified. As a side effect of this single application model, the original Mac developers were able to take advantage of several compromising simplifications that allowed great improvements in performance, running even faster than the much more expensive Lisa. But this design also led to several problems for future expansion. By assuming only one program would be running at a time, the engineers were able to ignore the concept of reentrancy, which is the ability for a program (or code library) to be stopped at any point, asked to do something else, and then return to the original task. In the case of QuickDraw for example, this means the system can store state information internally, like the current location of the window or the line style, knowing it would only change under control of the running program. Taking this one step further, the engineers left most of this state inside the application rather than in QuickDraw, thus eliminating the need to copy this data between the application and library. QuickDraw found this data by looking at known locations within the applications. This concept of sharing memory is a significant source of problems and crashes. If an application program writes incorrect data into these shared locations, it could cause QuickDraw to crash, thereby causing the computer to crash. Likewise, any problem in QuickDraw could cause it to overwrite data in the application, once again leading to crashes. In the case of a single-application operating system this was not a fatal limitation, because in that case a problem in either would require the application, or computer, to be restarted anyway. The other main issue was that early Macs lack a memory management unit (MMU), which precludes the possibility of several fundamental modern features. An MMU provides memory protection to ensure that programs cannot accidentally overwrite other program's memory, and provisions shared memory that allows data to be easily passed among libraries. Lacking shared memory, the API was instead written so the operating system and application shares all memory, which is what allows QuickDraw to examine the application's memory for settings like the line drawing mode or color. These limits meant that supporting the multitasking of more than one program at a time would be difficult, without rewriting all of this operating system and application code. Yet doing so would mean the system would run unacceptably slow on existing hardware. Instead, Apple adopted a system known as MultiFinder in 1987, which keeps the running application in control of the computer, as before, but allows an application to be rapidly switched to another, normally simply by clicking on its window. Programs that are not in the foreground are periodically given short bits of time to run, but as before, the entire process is controlled by the applications, not the operating system. Because the operating system and applications all share one memory space, it is possible for a bug in any one of them to corrupt the entire operating system, and crash the machine. Under MultiFinder, any crash anywhere will crash all running programs. Running multiple applications potentially increases the chances of a crash, making the system potentially more fragile. Adding greatly to the severity of the problem is the patching mechanism used to add functions to the operating system, known as CDEVs and INITs or Control Panels and Extensions. Third party developers also make use of this mechanism to add features, including screensavers and a hierarchical Apple menu. Some of these third-party control panels became almost universal, like the popular After Dark screensaver package. Because there was no standard for use of these patches, it is not uncommon for several of these add-ons — including Apple's own additions to the OS — to use the same patches, and interfere with each other, leading to more crashing. Copland design Copland was designed to consist of the Mac OS on top of a microkernel named Nukernel, which would handle basic tasks such as application startup and memory management, leaving all other tasks to a series of semi-special programs known as servers. For instance, networking and file services would not be provided by the kernel itself, but by servers that would be sent requests through interapplication communications. Copland consists of the combination of Nukernel, various servers, and a suite of application support libraries to provide implementations of the well-known classic Macintosh programming interface. Application services are offered through a single program known officially as the Cooperative Macintosh Toolbox environment, but universally referred to as the Blue Box. The Blue Box encapsulates an existing System 7 operating system inside a single process and address space. Mac programs run inside the Blue Box much as they do under System 7, as cooperative tasks that use the non-reentrant Toolbox calls. A worst-case scenario is that an application in the Blue Box crashes, taking down the entire Blue Box instance with it. This does not result in the system as a whole going down, however, and the Blue Box can be restarted. New applications written with Copland in mind, are able to directly communicate with the system servers and thereby gain many advantages in terms of performance and scalability. They can also communicate with the kernel to launch separate applications or threads, which run as separate processes in protected memory, as in most modern operating systems. These separate applications cannot use non-reentrant calls like QuickDraw, however, and thus could have no user interface. Apple suggested that larger programs could place their user interface in a normal Macintosh application, which would then start worker threads externally. Another key feature of Copland is that it is fully PowerPC (PPC) native. System 7 had been ported to the PowerPC with great success; large parts of the system run as PPC code, including both high-level functions, such as most of the user interface toolbox managers, and low-level functions, such as interrupt management. There is enough 68k code left in the system to be run in emulation, and especially user applications, however that the operating system must map some data between the two environments. In particular, every call into the Mac OS requires a mapping between the interrupt systems of the 68k and PPC. Removing these mappings would greatly improve general system performance. At WWDC 1996, engineers claimed that system calls would execute as much as 50% faster. Copland is also based on the then-recently defined Common Hardware Reference Platform, or CHRP, which standardized the Mac hardware to the point where it could be built by different companies and can run other operating systems (Solaris and AIX were two of many mentioned). This was a common theme at the time; many companies were forming groups to define standardized platforms to offer an alternative to the "Wintel" platform that was rapidly becoming dominant — examples include 88open, Advanced Computing Environment, and the AIM alliance. The fundamental second-system effect to challenge Copland's development and adoption would be getting all of these functions to fit into an ordinary Mac. System 7.5 already uses up about 2.5 megabytes (MB) of RAM, which is a significant portion of the total RAM in most contemporaneous machines. Copland is two systems in one, as its native foundation also hosts Blue Box, containing essentially a complete copy of System 7.5. Copland thus uses a Mach-inspired memory management system and relies extensively on shared libraries, with the goal being for Copland to be only some 50% larger than 7.5. History Pink and Blue In March 1988, technical middle managers at Apple held an offsite meeting to plan the future course of Mac OS development. Ideas were written on index cards; features that seemed simple enough to implement in the short term (like adding color to the user interface) were written on blue cards; longer-term goals—such as preemptive multitasking—were on pink cards; and long-range ideas like an object-oriented file system were on red cards. Development of the ideas contained on the blue and pink cards was to proceed in parallel, and at first, the two projects were known simply as "blue" and "pink". Apple intended to have the "blue" team (who came to call themselves the "Blue Meanies" after characters in the film Yellow Submarine) release an updated version of the existing Macintosh operating system in the 1990–1991 timeframe, and the Pink team to release an all-new OS around 1993. The Blue team delivered what became known as System 7 on May 13, 1991, but the Pink team suffered from second-system effect and its release date continued to slip into the indefinite future. Some of the reason for this can be traced to problems that would become widespread at Apple as time went on; as Pink became delayed, its engineers moved to Blue instead. This left the Pink team constantly struggling for staffing, and suffering from the problems associated with high employee turnover. Management ignored these sorts of technical development issues, leading to continual problems delivering working products. At this same time, the recently released NeXTSTEP was generating intense interest in the developer world. Features that were originally part of Red, were folded into Pink, and the Red project (also known as "Raptor") was eventually canceled. This problem was also common at Apple during this period; in order to chase the "next big thing", middle managers would add new features to their projects with little oversight, leading to enormous problems with feature creep. In the case of Pink, development eventually slowed to the point that the project appeared moribund. Taligent On April 12, 1991, Apple CEO John Sculley performed a secret demonstration of Pink running on an IBM PS/2 Model 70 to a delegation from IBM. Though the system was not fully functional, it resembled System 7 running on a PC. IBM was extremely interested, and over the next few months, the two companies formed an alliance to further development of the system. These efforts became public in early 1992, under the new name "Taligent". At the time, Sculley summed up his concerns with Apple's own ability to ship Pink when he stated "We want to be a major player in the computer industry, not a niche player. The only way to do that is to work with another major player." Infighting at the new joint company was legendary, and the problems with Pink within Apple soon appeared to be minor in comparison. Apple employees made T-shirts graphically displaying their prediction that the result would be an IBM-only project. On December 19, 1995, Apple officially pulled out of the project. IBM continued working alone with Taligent, and eventually released its application development portions under the new name "CommonPoint". This saw little interest and the project disappeared from IBM's catalogs within months. Business as usual While Taligent efforts continued, very little work addressing the structure of the original OS was carried out. Several new projects started during this time, notably the Star Trek project, a port of System 7 and its basic applications to Intel-compatible x86 machines, which reached internal demo status. But as Taligent was still a concern, it was difficult for new OS projects to gain any traction. Instead, Apple's Blue team continued adding new features to the same basic OS. During the early 1990s, Apple released a series of major new packages to the system; among them are QuickDraw GX, Open Transport, OpenDoc, PowerTalk, and many others. Most of these were larger than the original operating system. Problems with stability, which had existed even with small patches, grew along with the size and requirements of these packages, and by the mid-1990s the Mac had a reputation for instability and constant crashing. As the stability of the operating system collapsed, the ready answer was that Taligent would fix this with all its modern foundation of full reentrance, preemptive multitasking, and protected memory. When the Taligent efforts collapsed, Apple remained with an aging OS and no designated solutions. By 1994, the press buzz surrounding the upcoming release of Windows 95 started to crescendo, often questioning Apple's ability to respond to the challenge it presented. The press turned on the company, often introducing Apple's new projects as failures in the making. Another try Given this pressure, the collapse of Taligent, the growing problems with the existing operating system, and the release of System 7.5 in late 1994, Apple management decided that the decade-old operating system had run its course. A new system that did not have these problems was needed, and soon. Since so much of the existing system would be difficult to rewrite, Apple developed a two-stage approach to the problem. In the first stage, the existing system would be moved on top of a new kernel-based OS with built-in support for multitasking and protected memory. The existing libraries, like QuickDraw, would take too long to be rewritten for the new system and would not be converted to be reentrant. Instead, a single paravirtualized machine, the Blue Box, keeps applications and legacy code such as QuickDraw in a single memory block so they continue to run as they had in the past. Blue Box runs in a distinct Copland memory space, so crashing legacy applications or extensions within Blue Box cannot crash the entire machine. In the next stage of the plan, once the new kernel was in place and this basic upgrade was released, development would move on to rewriting the older libraries into new forms that could run directly on the new kernel. At that point, applications would gain some added modern features. In the musical code-naming pattern where System 7.5 is code-named "Mozart", this intended successor is named "Copland" after composer Aaron Copland. In turn, its proposed successor system, Gershwin, would complete the process of moving the entire system to the modern platform, but work on Gershwin would never officially begin. Development The Copland project was first announced in May 1994. Parts of Copland, most notably an early version of the new file system, were demonstrated at Apple's Worldwide Developers Conference in May 1995. Apple also promised that a beta release of Copland would be ready by the end of the year, for final commercial release in early 1996. Gershwin would follow the next year. Throughout the year, Apple released several mock-ups to various magazines showing what the new system would look like, and commented continually that the company was fully committed to this project. By the end of the year, however, no Developer Release had been produced. As had happened in the past during the development of Pink, developers within Apple soon started abandoning their own projects in order to work on the new system. Middle management and project leaders fought back by claiming that their project was vital to the success of the system, and moving it into the Copland development stream. Thus, it could not be canceled along with their employees being removed to work on some other part of Copland anyway. This process took on momentum across the next year. Soon the project looked less like a new operating system and more like a huge collection of new technologies; QuickDraw GX, System Object Model (SOM), and OpenDoc became core components of the system, while completely unrelated technologies like a new file management dialog box (the open dialog) and themes support appeared also. The feature list grew much faster than the features could be completed, a classic case of creeping featuritis. An industry executive noted that "The game is to cut it down to the three or four most compelling features as opposed to having hundreds of nice-to-haves, I'm not sure that's happening." As the "package" grew, testing it became increasingly difficult and engineers were commenting as early as 1995 that Apple's announced 1996 release date was hopelessly optimistic: "There's no way in hell Copland ships next year. I just hope it ships in 1997." In mid-1996, information was leaked that Copland would have the ability to run applications written for other operating systems, including Windows NT. Simultaneously allegedly confirmed by Copland engineers and authoritatively denied by Copland project management, this feature had supposedly been in development for more than three years. One user claimed to have been told about these plans by members of the Copland development team. Some analysts projected that this ability would increase Apple's penetration into the enterprise market, others said it was "game over" and was only a sign of the Mac platform's irrelevancy. Developer Release At WWDC 1996, Apple's new CEO, Gil Amelio, used the keynote to talk almost exclusively about Copland, now known as System 8. He repeatedly stated that it was the only focus of Apple engineering and that it would ship to developers in a few months, with a full release planned for late 1996. Very few, if any, demos of the running system were shown at the conference. Instead, various pieces of the technology and user interface that would go into the package (such as a new file management dialog) were demonstrated. Little of the core system's technology was demonstrated and the new file system that had been shown a year earlier was absent. There was one way to actually use the new operating system – by signing up for time in the developer labs. This did not go well: Several people at the show complained about the microkernel's lack of sophistication, notably the lack of symmetric multiprocessing, a feature that would be exceedingly difficult to add to a system due to ship in a few months. After that, Amelio came back on stage and announced that they would be adding that to the feature list. In August 1996, "Developer Release 0" was sent to a small number of selected partners. Far from demonstrating improved stability, it often crashed after doing nothing at all, and was completely unusable for development. In October, Apple moved the target delivery date to "sometime", hinting that it might be 1997. One of the groups most surprised by the announcement was Apple's own hardware team, who had been waiting for Copland to allow the PowerPC to be natively represented, unburdened of software legacy. Members of Apple's software QA team joked that, given current resources and the number of bugs in the system, they could clear the program for shipping sometime around 2030. Cancellation Later in August 1996, the situation was no better. Amelio complained that Copland was "just a collection of separate pieces, each being worked on by a different team ... that were expected to magically come together somehow." Hoping to salvage the situation, Amelio hired Ellen Hancock away from National Semiconductor to take over engineering and get Copland development back on track. After a few months on the job, Hancock came to the conclusion that the situation was hopeless; given current development and engineering, she believed Copland would never ship. Instead, she suggested that the various user-facing technologies in Copland be rolled out in a series of staged releases, instead of a single big release. To address the aging infrastructure underneath these technologies, Amelio suggested looking outside the company for an unrelated new operating system. Candidates considered were Sun's Solaris and Windows NT. Hancock reportedly was in favor of going with Solaris, while Amelio preferred Windows. Amelio even reportedly called Bill Gates to discuss the idea, and Gates promised to put Microsoft engineers to work porting QuickDraw to NT. Apple officially canceled Copland in August 1996 and reused the Mac OS 8 product name for codename Tempo, a Copland-inspired major update to Mac OS 7.6. The CD envelopes for the developer's release had been printed, but the discs had not been mastered. After lengthy discussions with Be and rumors of a merger with Sun Microsystems, many were surprised at Apple's December 1996 announcement that they were purchasing NeXT and bringing Steve Jobs on in an advisory role. Amelio quipped that they "choose Plan A instead of Plan Be." The project to port NeXTSTEP to the Macintosh platform was named Rhapsody and was to be the core of Apple's cross-platform operating system strategy. This would inherit OpenStep's existing support for PowerPC, Intel x86, and DEC Alpha CPU architectures, and an implementation of the OpenStep libraries running on Windows NT. This would in effect open the Windows application market to Macintosh developers as they could license the library from Apple for distribution with their product, or depend on an existing installation. Legacy Following Hancock's plan, development of System 7.5 continued, with several technologies originally slated for Copland being incorporated into the base OS. Apple embarked on a buying campaign, acquiring the rights to various third-party system enhancements and integrating them into the OS. The Extensions Manager, hierarchical Apple menu, collapsing windows, the menu bar clock, and sticky notes—all were developed outside of Apple. Stability and performance were improved by Mac OS 7.6, which dropped the "System" moniker in favor of "Mac OS". Eventually, many features developed for Copland, including the new multithreaded Finder and support for themes (the default Platinum was the only theme included) were rolled into the unreleased beta of Mac OS 7.7, which was instead rebranded and launched as Mac OS 8. With the return of Jobs, this rebranding to version 8 also allowed Apple to exploit a legal loophole to terminate third-party manufacturers' licenses to System 7 and effectively shut down the Macintosh clone market. Later, Mac OS 8.1 finally added the new file system and Mac OS 8.6 updated the nanokernel to handle limited support for preemptive tasks. Its interface is Multiprocessing Services 2.x and later, but there is no process separation and the system still uses cooperative multitasking between processes. Even a process that is Multiprocessing Services-aware still has a part that runs in the Blue Box, a task that also runs all single-threaded programs and the only task that can run 68k code. The Rhapsody project was canceled after several Developer Preview releases, support for running on non-Macintosh platforms was dropped, and it was eventually released as Mac OS X Server 1.0. In 2001 this foundation was coupled to the Carbon library and Aqua user interface to form the modern Mac OS X product. Versions of Mac OS X prior to the Intel release of Mac OS X 10.4 (Tiger), also use the rootless Blue Box concept in the form of Classic to run applications written for older versions of Mac OS. Several features originally seen in Copland demos, including its advanced Find command, built-in Internet browser, piles of folders, and support for video-conferencing, have reappeared in subsequent releases of Mac OS X as Spotlight, Safari, Stacks, and iChat AV, respectively, although the implementation and user interface for each feature is very different. Hardware requirements According to the documentation included in the Developer Release, Copland supports the following hardware configurations: NuBus-based Macintoshes: 6100/60, 6100/60AV (no AV functions), 6100/66, 6100/66 AV (no AV functions), 6100/66 DOS (no DOS functions), 7100/66, 7100/66 AV (no AV functions), 7100/80, 7100/80 AV (no AV functions), 8100/80/ 8100/100/ 8100/100 AV (no AV functions), 8100/110 NuBus-based Performas: 6110CD, 6112CD, 6115CD, 6117CD, 6118CD PCI-based Macintoshes: 7200/70, 7200/90, 7500/100, 8500/120, 9500/120, 9500/132 Drives formatted with Drive Setup For DR1 and earlier, the installer requires System 7.5 or later on a hard disk of 250MB or greater capacity. Display set to 256 colors (8-bit) or Thousands (16-bit). See also Classic Mac OS MkLinux Workplace OS BeOS Notes References Citations Bibliography External links Copland retrospectives at MacKiDo, iGeek, and iGeek Apple's Copland project: An OS for the common man, development history "A Time Machine trip to the mid-'90s", MacWorld article with screenshots from Copland The Long View, a retrospective analysis of the development cycle and code legacy of Copland into MacOS 8 and Carbon Apple's Copland Reference Documentation Computer Chronicles: Mac Clones, with a demo of Copland Businessweek article on Copland Aaron Copland Apple Inc. operating systems Macintosh operating systems Macintosh platform Microkernel-based operating systems Microkernels PowerPC operating systems Object-oriented operating systems Vaporware

Operating System (OS)

HeliOS Helios is a discontinued Unix-like operating system for parallel computers. It was developed and published by Perihelion Software. Its primary architecture is the Transputer. Helios' microkernel implements a distributed namespace and messaging protocol, through which services are accessed. A POSIX compatibility library enables the use of Unix application software, and the system provides most of the usual Unix utilities. Work on Helios began in the autumn of 1986. Its success was limited by the commercial failure of the Transputer, and efforts to move to other architectures met with limited success. Perihelion ceased trading in 1998. Development In the early 1980s, Tim King joined MetaComCo from the University of Bath, bringing with him some rights to an operating system called TRIPOS. MetaComCo secured a contract from Commodore to work on AmigaOS, with the AmigaDOS component being derived from TRIPOS. In 1986, King left MetaComCo to found Perihelion Software, and began development of a parallel operating system, initially targeted at the INMOS Transputer series of processors. Helios extended TRIPOS' use of a light-weight message passing architecture to networked parallel machines. Helios 1.0 was the first commercial release in the summer of 1988, followed by version 1.1 in autumn 1989, 1.1a in early 1990, 1.2 in December 1990 followed by 1.2.1 and 1.2.2 updates. Version 1.3 was a significant upgrade with numerous utility, library, server and driver improvements. The last commercial release was 1.3.1. Later Tim King and Nick Garnett gave permission to release the sources under the GNU Public License v3. Kernel and nucleus Helios was designed for a network of multiple nodes, connected by multiple high-bandwidth communications links. Nodes can be dedicated processing nodes, or processors with attached I/O devices. Small systems might consist of a host PC or workstation connected to a set of several processing nodes, while larger systems might have hundreds of processing nodes supported by dedicated nodes for storage, graphics, or user terminals. A Helios network requires at least one I/O Server node that is able to provide a file system server, console server and reset control for the processing nodes. At power on, the Helios nucleus is bootstrapped from the I/O server into the network. Each node is booted using a small first-stage loader that then downloads and initialises the nucleus proper. Once running, a node communicates with its neighbours, booting them in turn, if required. The Helios nucleus is composed of the kernel, libraries, loader service and the processor manager service. Kernel The Helios kernel is effectively a microkernel, providing a minimal abstraction above the hardware with most services implemented as non-privileged server processes. It provides memory allocation, process management, message passing and synchronisation primitives. Libraries The Helios nucleus contains three libraries: the system, server and utility libraries. The utility library provides some basic library routines for C programming that are shared by the other libraries. The system library provides the basic kernel interface, converting C function calls into messages sent to and from the kernel. It implements an abstraction that allows communication between processes regardless of their location in the network. The server library provides name space support functions for writing Helios servers, as described below. Loader and processor manager The remaining components of the nucleus are the loader and processor manager servers. Once the kernel is loaded, these processes are bootstrapped, and they integrate the newly running node into the Helios network. Naming and servers A key feature in Helios is its distributed name system. A Helios network implements a single unified name space, with a virtual root node, optional virtual network structuring nodes, nodes for each processor, and sub-processor name spaces provided by services. Names are similar to those in Unix, using a forward slash separating character and textual naming elements. The name space is managed by the network server, which is started by the I/O server once the nucleus is booted on its first attached node. The network server uses a provided network map to allocate processor names and initialise drivers for hardware devices at specific nodes in the network. The kernel includes a name resolver, and manages a local cache of routes to previously resolved names. Servers are Helios processes that implement the General Server Protocol, typically with the support of the server library. The server protocol is conceptually similar to the Unix VFS API, and more closely to Plan 9's 9P. It requires that servers represent their resources as files, with standardised open/read/write/close-style operations. Similar to facilities such as /proc in Plan 9 and other Unix-like operating systems, resources such as files, I/O devices, users, and processes are all represented as virtual files in the namespace served by their managing process. Key servers in Helios are the previously mentioned loader, processor manager and network server, together with the session manager, the window server and the file server. Others include the keyboard, mouse, RS232 and Centronics servers (built into the host I/O server), the null server (like Unix's /dev/null), and the logger server (like Unix's syslog). Programming and utilities From a user's perspective, Helios is quite similar to Unix. Most of the usual utility programs are provided, some with extensions to reflect the availability of multiple machines. What is not immediately apparent is that Helios extends the notion of Unix pipes into a language called Component Distribution Language (CDL). In CDL, a typical Unix shell pipeline such as is called a task force, and is transparently distributed by the Task Force Manager server across the available CPUs. CDL extends traditional Unix syntax with additional operators for bi-directional pipes, sequential and parallel process farm operators, load balancing and resource management. Helios applications can be written using C, C++, FORTRAN and Modula-2. The POSIX library assists in porting existing Unix software, and provides a familiar environment for programmers. Helios does not support programs written in the occam programming language. Hardware Helios was predominantly intended to be used with Transputer systems. It is compatible with products from various manufacturers including INMOS' TRAM systems, the Meiko CS, Parsytec MultiCluster and SuperCluster, and the Telmat T.Node. The Atari Transputer Workstation was perhaps the highest profile Helios hardware, at least outside academia. Helios can run on T4xx and T8xx, 32-bit Transputers (but not the T2xx 16-bit models) and includes device drivers for various SCSI, Ethernet and graphics hardware from Inmos, Transtech, and others. In its later versions, Helios was ported to the TI TMS320C40 DSP and to the ARM architecture, the latter used by the Active Book tablet device. References Further reading External links Ram Meenakshisundaram's Transputer Home Page Transputer.net Helios Library Distributed operating systems Microkernel-based operating systems Unix variants 1988 software

Operating System (OS)

TR-DOS TR-DOS is a disk operating system for the ZX Spectrum with Beta Disc and Beta 128 disc interfaces. TR-DOS and Beta disc were developed by Technology Research Ltd (UK), in 1984. It became a standard, and most disk releases for the ZX Spectrum, especially of modern programs are made for TR-DOS as opposed to other disk systems. Current emulators support TR-DOS disk images in the formats .TRD or .SCL. A clone of this interface is also used in the Russian Pentagon and Scorpion machines. The latest official firmware version is 5.03 (1986). Unofficial versions with various enhancements and bug-fixes have been released since 1990, with the latest being 6.10E (2006). TR-DOS handles SS/DS, SD/DD floppy disks. All modern versions support RAM Disk and some versions support hard disks. Commands The following list of commands is supported by TR-DOS V4. 40 CAT CLOSE COPY ERASE FORMAT GO TO INPUT LOAD MOVE NEW OPEN PRINT RETURN RUN SAVE Utility programs include: FILER TAPECOPY (replaces BACKUP, COPY and SCOPY utility programs in TR-DOS V3) See also iS-DOS CP/M DISCiPLE References External links World of Spectrum Virtual TR-DOS Web TR-DOS. Encyclopedia of TR-DOS, ZX Games Microcomputer software ZX Spectrum Disk operating systems

Operating System (OS)

Xbox Linux Xbox Linux was a project that ported the Linux operating system to the Xbox video game console. Because the Xbox uses a digital signature system to prevent the public from running unsigned code, one must either use a modchip, or a softmod. Originally, modchips were the only option; however, it was later demonstrated that the TSOP chip on which the Xbox's BIOS is held may be reflashed. This way, one may flash on the "Cromwell" BIOS, which was developed legally by the Xbox Linux project. Catalyzed by a large cash prize for the first team to provide the possibility of booting Linux on an Xbox without the need of a hardware hack, numerous software-only hacks were also found. For example, a buffer overflow was found in the game 007: Agent Under Fire that allowed the booting of a Linux loader ("xbeboot") straight from a save game. The Xbox is essentially a PC with a custom 733 MHz Intel Pentium III processor, a 10 GB hard drive (8 GB of which is accessible to the user), 64MB of RAM (although on all earlier boxes this is upgradable to 128MB), and 4 USB ports. (The controller ports are actually USB 1.1 ports with a modified connector.) These specifications are enough to run several readily available Linux distributions. From the Xbox-Linux home page: The Xbox is a legacy-free PC by Microsoft that consists of an Intel Celeron 733 MHz CPU, an nVidia GeForce 3MX, 64 MB of RAM, a 8/10 GB hard disk, a DVD drive and 10/100 Ethernet. As on every PC, you can run Linux on it. An Xbox with Linux can be a full desktop computer with mouse and keyboard, a web/email box connected to TV, a server or router or a node in a cluster. You can either dual-boot or use Linux only; in the latter case, you can replace both IDE devices. And yes, you can connect the Xbox to a VGA monitor. Uses An Xbox with Linux installed can act as a full desktop computer with mouse and keyboard, a web/email box connected to a television, a server, router or a node in a cluster. One can either dual-boot or use Linux only; in the latter case, one can replace both IDE devices. One can also connect the Xbox to a VGA monitor. A converter is needed to use keyboards/mice in the controller ports; however this is not difficult, as the Xbox uses standard USB with a proprietary port. Currently only a few distributions of Xbox Linux will run on the version 1.6 Xbox (the third newest version, including 1.6b). Xboxes with modchips and the Cromwell bios installed can run more distributions than those with only a softmod. This is mainly due to issues with the video chip used in version 1.6 Xboxes that was developed exclusively by Microsoft and which has no source code available at this time. This can cause significant overscan on all four sides of the screen when a different kernel than the original is loaded. Softmod One of the more popular ways of installing Xbox Linux is through a softmod, which does not require a modchip to use. The Xbox Linux softmod utilizes a save exploit found in the original run of MechAssault, Splinter Cell, 007: Agent Under Fire, and Tony Hawk's Pro Skater 4. The method involves loading a hacked save file transferred to the Xbox's Hard Drive. When the save file is loaded, the MechInstaller is initiated. The Xbox Live option on the dashboard is replaced with the new Linux option after rebooting the system. Another softmod that can be used is the hotswap exploit which will unlock the Xbox hard drive long enough to allow one to modify it. There is also a way to completely replace the Xbox's stock BIOS with a "Cromwell" BIOS, which is completely legal and is solely for Linux on the Xbox. However, once the TSOP (BIOS chip) is flashed with "Cromwell", the Xbox can no longer play Xbox games or run native Xbox executables (.xbe files, akin to .exe for Windows). List of distributions There are several distributions of Xbox Linux, most of which are based on PC Linux distributions. See also Free60 Linux for PlayStation 2 OtherOS References External links Project site on SourceForge.net Xbox Hacking official document SoftMod Xbox for Free (Hotswap Technique!) Platform-specific Linux distributions Xbox (console) software Game console operating systems Discontinued Linux distributions Linux distributions

Operating System (OS)

SPIN (operating system) The SPIN operating system is a research project implemented in the computer programming language Modula-3, and is an open source project. It is designed with three goals: flexibility, safety, and performance. SPIN was developed at the University of Washington. The kernel can be extended by dynamic loading of modules which implement interfaces that represent domains. These domains are defined by Modula-3 INTERFACE. All kernel extensions are written in Modula-3 safe subset with metalanguage constructs and type safe casting system. The system also issued a special run-time extension compiler. One set of kernel extensions provides an application programming interface (API) that emulates the Digital Unix system call interface. This allows Unix applications to run on SPIN. References External links Free software operating systems Microkernel-based operating systems Microkernels 1994 software

Operating System (OS)

HP-UX HP-UX (from "Hewlett Packard Unix") is Hewlett Packard Enterprise's proprietary implementation of the Unix operating system, based on Unix System V (initially System III) and first released in 1984. Recent versions support the HP 9000 series of computer systems, based on the PA-RISC instruction set architecture, and HPE Integrity Servers, based on Intel's Itanium architecture. Earlier versions of HP-UX supported the HP Integral PC and HP 9000 Series 200, 300, and 400 computer systems based on the Motorola 68000 series of processors, as well as the HP 9000 Series 500 computers based on HP's proprietary FOCUS architecture. HP-UX was the first Unix to offer access control lists for file access permissions as an alternative to the standard Unix permissions system. HP-UX was also among the first Unix systems to include a built-in logical volume manager. HP has had a long partnership with Veritas Software, and uses VxFS as the primary file system. It is one of four commercial operating systems that have versions certified to The Open Group's UNIX 03 standard. (The others are macOS, AIX and Huawei's EulerOS.) Characteristics HP-UX 11i offers a common shared disks for its clustered file system. HP Serviceguard is the cluster solution for HP-UX. HP Global Workload Management adjusts workloads to optimize performance, and integrates with Instant Capacity on Demand so installed resources can be paid for in 30-minute increments as needed for peak workload demands. HP-UX offers operating system-level virtualization features such as hardware partitions, isolated OS virtual partitions on cell-based servers, and HP Integrity Virtual Machines (HPVM) on all Integrity servers. HPVM supports guests running on HP-UX 11i v3 hosts – guests can run Linux, Windows Server, OpenVMS or HP-UX. HP supports online VM guest migration, where encryption can secure the guest contents during migration. HP-UX 11i v3 scales as follows (on a SuperDome 2 with 32 Intel Itanium 9560 processors): 256 processor cores 8 TB main memory 32 TB maximum file system 16 TB maximum file size 128 million ZB—16 million logical units each up to 8 ZB. Security The 11i v2 release introduced kernel-based intrusion detection, strong random number generation, stack buffer overflow protection, security partitioning, role-based access management, and various open-source security tools. HP classifies the operating system's security features into three categories: data, system and identity: Context dependent files Release 6.x (together with 3.x) introduced the context dependent files (CDF) feature, a method of allowing a fileserver to serve different configurations and binaries (and even architectures) to different client machines in a heterogeneous environment. A directory containing such files had its suid bit set and was made hidden from both ordinary and root processes under normal use. Such a scheme was sometimes exploited by intruders to hide malicious programs or data. CDFs and the CDF filesystem were dropped with release 10.0. Supported hardware platforms HP-UX operating systems supports a variety of PA-RISC systems. The 11.0 added support for Integrity-based servers for the transition from PA-RISC to Itanium. HP-UX 11i v1.5 is the first version that supported Itanium. On the introduction of HP-UX 11i v2 the operating system supported both of these architectures. BL series HP-UX 11i supports HPE Integrity Servers of HP BL server blade family. These servers use the Intel Itanium architecture. CX series HP-UX 11i v2 and 11i v3 support HP's CX series servers. CX stands for carrier grade and is used mainly for telco industry with -48V DC support and is NEBS certified. Both of these systems contain Itanium Mad6M processors and are discontinued. RX series HP-UX supports HP's RX series of servers. Release history Prior to the release of HP-UX version 11.11, HP used a decimal version numbering scheme with the first number giving the major release and the number following the decimal showing the minor release. With 11.11, HP made a marketing decision to name their releases 11i followed by a v(decimal-number) for the version. The i was intended to indicate the OS is Internet-enabled, but the effective result was a dual version-numbering scheme. Version history Versions 1.0 (1982) First release for HP 9000 Series 500. HP-UX for Series 500 was substantially different from HP-UX for any other HP machines, as it was layered atop a Series 500 specific operating system called SUNOS (unrelated to Sun Microsystems' SunOS). 1.0 (1984) AT&T System III based. Support for the HP Integral PC (HP 9807A). The kernel runs from ROM; other commands are disk based. 2.0 (1984) First release for HP's early Motorola 68000-based workstations (HP 9816U, HP 9826U, HP 9836U) 5.0 (1985) AT&T System V based. Distinct versions were available for the Integral PC, the Series 200/300 and the Series 500. Introduced the proprietary Starbase graphics API for the Series 200, 300 and 500. The Series 300 5.x releases included a proprietary windowing system built on top of Starbase named HP Windows/9000, which was also available as an optional extra for Series 500 hardware. 3.x (1988) HP 9000 Series 600/800 only. Note: 2.x/3.x (for Series 600/800) were developed in parallel with 5.x/6.x (for Series 200/300/400), so, for example, 3.x was really contemporary with 6.x. The two lines were united at HP-UX 7.x. 6.x (1988) Support for HP 9000 Series 300 only. Introduced sockets from 4.3BSD. This version (together with 3.x) also introduced the above-discussed context dependent files (CDF), which were removed in release 10 because of their security risks. The 6.2 release added X11, superseding HP Windows/9000 and X10. 6.5 allowed Starbase programs to run alongside X11 programs. 7.x (1990) Support for HP 9000 Series 300/400, 600/700 (in 7.03) /800 HP systems. Provided OSF/Motif. Final version to include the HP Windows/9000 windowing system. 8.x (January 1991) Support for HP 9000 Series 300/400 600/700/800 systems. Shared libraries introduced. 9.x (July 1992) 9.00, 9.02, 9.04 (Series 600/800), 9.01, 9.03, 9.05, 9.07 (Series 300/400/700), 9.08, 9.09, 9.09+ (Series 700 only), 9.10 (Series 300/400 only). These provided support for the HP 9000 Series 300, 700 and 800 systems. Introduced System Administration Manager (SAM). The Logical Volume Manager (LVM) was presented in 9.00 for the Series 800. Adopted the Visual User Environment desktop. 10.0 (1995) This major release saw a convergence of the operating system between the HP 9000 Series 700 (workstation) and Series 800 (server) systems, dropping support for previous lines. There was also a significant change in the layout in the system files and directories, based on the AT&T UNIX System V Release 4 standard. Applications were removed from /usr and moved under /opt; startup configuration files were placed under /etc/rc.config.d; users were moved to /home from /users. Software for HP-UX was now packaged, shipped, installed, and removed via the Software Distributor (SD) tools. LVM was also made available for Series 700. 10.10 (1996) Introduced the Common Desktop Environment. UNIX95 compliance. 10.20 (1996) This release included support for 64-bit PA-RISC 2.0 processors. Pluggable Authentication Modules (PAM) were introduced for use within CDE. The root file system could be configured to use the Veritas File System (VxFS). For legacy as well as technical reasons, the file system used for the boot kernel remained Hi Performance FileSystem (HFS, a variant of UFS) until version 11.23. 10.20 also supported 32-bit user and group identifiers. The prior limit was 60,000, or 16-bit. This and earlier releases of HP-UX are now effectively obsolete, and support by HP ended on June 30, 2003. 10.24 This is a Virtual Vault release of HP-UX, providing enhanced security features. Virtual Vault is a compartmentalised operating system in which each file is assigned a compartment and processes only have access to files in the appropriate compartment and unlike most other UNIX systems the superuser (or root) does not have complete access to the system without following correct procedures. 10.30 (1997) This was primarily a developer release with various incremental enhancements. It provided the first support for kernel threads, with a 1:1 thread model (each user thread is bound to one kernel thread). 11.00 (1997) The first HP-UX release to also support 64-bit addressing. It could still run 32-bit applications on a 64-bit system. It supported symmetric multiprocessing, Fibre Channel, and NFS PV3. It also included tools and documentation to convert 32-bit code to 64-bit. 11.04 Virtual Vault release. 11.10 This was a limited release to support the HP 9000 V2500 SCA (Scalable Computing Architecture) and V2600 SCA servers. It also added JFS 3.3, AutoFS, a new ftpd, and support for up to 128 CPUs. It was not available separately. 11.11 (2000) 11i v1 This release of HP-UX introduced the concept of Operating Environments. It was released in December 2000. These are bundled groups of layered applications intended for use with a general category of usage. The available types were the Mission Critical, Enterprise, Internet, Technical Computing, and Minimal Technical OEs. (The last two were intended for HP 9000 workstations.) The main enhancements with this release were support for hard partitions, Gigabit Ethernet, NFS over TCP/IP, loadable kernel modules, dynamic kernel tunable parameters, kernel event Notifications, and protected stacks. 11.20 (2001) 11i v1.5 This release of HP-UX was the first to support the new line of Itanium-based (IA-64) systems. It was not intended for mission critical computing environments and did not support HP's ServiceGuard cluster software. It provided support for running PA-RISC compiled applications on Itanium systems, and for Veritas Volume Manager 3.1. 11.22 (2002) 11i v1.6 An incremental release of the Itanium version of HP-UX. This version achieved 64-way scalability, m:n threads, added more dynamic kernel tunable parameters, and supported HP's Logical Volume Manager on Itanium. It was built from the 11i v1 source code stream. 11.23 (2003) 11i v2 The original release of this version was in September 2003 to support the Itanium-based systems. In September 2004 the OS was updated to provide support for both Itanium and PA-RISC systems. Besides running on Itanium systems, this release includes support for ccNUMA, web-based kernel and device configuration, IPv6, and stronger random number generation. 11.31 (2007) 11i v3 This release supports both PA-RISC and Itanium. It was released on February 15, 2007. Major new features include native multipathing support, a unified file cache, NFSv4, Veritas ClusterFS, multi-volume VxFS, and integrated virtualization. Hyperthreading is supported on Itanium systems with Montecito and Tukwila processors. HP-UX 11i v3 conforms to The Open Group's UNIX 03 standard. Updates for 11i v3 have been released every 6 months, with the latest revision being B.11.31.1805, released in May 2018. HP has moved to a cadence of one major HP-UX operating system update per year. HP-UX 11i operating environments HP bundles HP-UX 11i with programs in packages they call Operating Environments (OEs). The following lists the currently available HP-UX 11i v3 OEs: HP-UX 11i v3 Base OE (BOE) Includes the full HP-UX 11i operating system plus file system and partitioning software and applications for Web serving, system management and security. BOE includes all the software formerly in FOE & TCOE (see below), plus software formerly sold stand-alone (e.g. Auto Port Aggregator). HP-UX 11i v3 Virtualization Server OE (VSE-OE) Includes everything in BOE plus GlancePlus performance analysis and software mirroring, and all Virtual Server Environment software which includes virtual partitions, virtual machines, workload management, capacity advisor and applications. VSE-OE includes all the software formerly in EOE (see below), plus additional virtualization software. HP-UX 11i v3 High Availability OE (HA-OE) Includes everything in BOE plus HP Serviceguard clustering software for system failover and tools to manage clusters, as well as GlancePlus performance analysis and software mirroring applications. HP-UX 11i v3 Data Center OE (DC-OE) Includes everything in one package, combining the HP-UX 11i operating system with virtualization. Everything in the HA-OE and VSE-OE is in the DC-OE. Solutions for wide-area disaster recovery and the compiler bundle are sold separately. HP-UX 11i v2 (11.23) HP dropped support for v2 in December 2010. Currently available HP-UX 11i v2 OEs include: HP-UX 11i v2 Foundation OE (FOE) Designed for Web servers, content servers and front-end servers, this OE includes applications such as HP-UX Web Server Suite, Java, and Mozilla Application Suite. This OE is bundled as HP-UX 11i FOE. HP-UX 11i v2 Enterprise OE (EOE) Designed for database application servers and logic servers, this OE contains the HP-UX 11i v2 Foundation OE bundles and additional applications such as GlancePlus Pak to enable an enterprise-level server. This OE is bundled as HP-UX 11i EOE. HP-UX 11i v2 Mission Critical OE (MCOE) Designed for the large, powerful back-end application servers and database servers that access customer files and handle transaction processing, this OE contains the Enterprise OE bundles, plus applications such as MC/ServiceGuard and Workload Manager to enable a mission-critical server. This OE is bundled as HP-UX 11i MCOE. HP-UX 11i v2 Minimal Technical OE (MTOE) Designed for workstations running HP-UX 11i v2, this OE includes the Mozilla Application Suite, Perl, VxVM, and Judy applications, plus the OpenGL Graphics Developer's Kit. This OE is bundled as HP-UX 11i MTOE. HP-UX 11i v2 Technical Computing OE (TCOE) Designed for both compute-intensive workstation and server applications, this OE contains the MTOE bundles plus extensive graphics applications, MPI and Math Libraries. This OE is bundled as HP-UX 11i-TCOE. HP-UX 11i v1 (11.11) According to HP's roadmap, was sold through December 2009, with continued support for v1 at least until December 2015. See also HP Roman-8 (character set) References Scott W. Y. Wang and Jeff B. Lindberg "HP-UX: Implementation of UNIX on the HP 9000 Series 500 Computer Systems", Hewlett-Packard Journal (volume 35 number 3, March 1984) Frank McConnell, More about the HP 9000'', gaby.de Hewlett-Packard Company, "HP-UX Reference, Vol. 1, HP-UX Release 6.5, December 1988", HP Part number 09000-90009 External links HP-UX Home HP-UX Software & Update Information HP software UNIX System V

Operating System (OS)

Exokernel Exokernel is an operating system kernel developed by the MIT Parallel and Distributed Operating Systems group, and also a class of similar operating systems. Operating systems generally present hardware resources to applications through high-level abstractions such as (virtual) file systems. The idea behind exokernels is to force as few abstractions as possible on application developers, enabling them to make as many decisions as possible about hardware abstractions. Exokernels are tiny, since functionality is limited to ensuring protection and multiplexing of resources, which is considerably simpler than conventional microkernels' implementation of message passing and monolithic kernels' implementation of high-level abstractions. Implemented abstractions are called library operating systems; they may request specific memory addresses, disk blocks, etc. The kernel only ensures that the requested resource is free, and the application is allowed to access it. This low-level hardware access allows the programmer to implement custom abstractions, and omit unnecessary ones, most commonly to improve a program's performance. It also allows programmers to choose what level of abstraction they want, high, or low. Exokernels can be seen as an application of the end-to-end principle to operating systems, in that they do not force an application program to layer its abstractions on top of other abstractions that were designed with different requirements in mind. For example, in the MIT Exokernel project, the Cheetah web server stores preformatted Internet Protocol packets on the disk, the kernel provides safe access to the disk by preventing unauthorized reading and writing, but how the disk is abstracted is up to the application or the libraries the application uses. Motivation Traditionally kernel designers have sought to make individual hardware resources invisible to application programs by requiring the programs to interact with the hardware via some abstraction model. These models include file systems for disk storage, virtual address spaces for memory, schedulers for task management, and sockets for network communication. These abstractions of the hardware make it easier to write programs in general, but limit performance and stifle experimentation in new abstractions. A security-oriented application might need a file system that does not leave old data on the disk, while a reliability-oriented application might need a file system that keeps such data for failure recovery. One option is to remove the kernel completely and program directly to the hardware, but then the entire machine would be dedicated to the application being written (and, conversely, the entire application codebase would be dedicated to that machine). The exokernel concept is a compromise: let the kernel allocate the basic physical resources of the machine (e.g. disk blocks, memory pages, and processor time) to multiple application programs, and let each program decide what to do with these resources. The program can then link to a support library that implements the abstractions it needs (or it can implement its own). MIT exokernels MIT developed two exokernel-based operating systems, using two kernels: Aegis, a proof of concept with limited support for storage, and XOK, which applied the exokernel concept more thoroughly. An essential idea of the MIT exokernel system is that the operating system should act as an executive for small programs provided by the application software, which are constrained only by the requirement that the exokernel must be able to guarantee that they use the hardware safely. Design The MIT exokernel manages hardware resources as follows: Processor The kernel represents the processor resources as a timeline from which programs can allocate intervals of time. A program can yield the rest of its time slice to another designated program. The kernel notifies programs of processor events, such as interrupts, hardware exceptions, and the beginning or end of a time slice. If a program takes a long time to handle an event, the kernel will penalize it on subsequent time slice allocations; in extreme cases the kernel can abort the program. Memory The kernel allocates physical memory pages to programs and controls the translation lookaside buffer. A program can share a page with another program by sending it a capability to access that page. The kernel ensures that programs access only pages for which they have a capability. Disk storage The kernel identifies disk blocks to the application program by their physical block address, allowing the application to optimize data placement. When the program initializes its use of the disk, it provides the kernel with a function that the kernel can use to determine which blocks the program controls. The kernel uses this callback to verify that when it allocates a new block, the program claims only the block that was allocated in addition to those it already controlled. Networking The kernel implements a programmable packet filter, which executes programs in a byte code language designed for easy security-checking by the kernel. Applications The available library operating systems for Exokernel include the custom ExOS system and an emulator for BSD. In addition to these, the exokernel team created the Cheetah web server, which uses the kernel directly. History The exokernel concept has been around since at least 1994, but exokernels are still a research effort and have not been used in any major commercial operating systems. A concept operating exokernel system is Nemesis, written by University of Cambridge, University of Glasgow, Citrix Systems, and the Swedish Institute of Computer Science. MIT has also built several exokernel-based systems, including ExOS. See also Hybrid kernel Hypervisor Kernel (computer science) Microkernel Monolithic kernel Nanokernel Paravirtualization Rump kernel Single address space operating system (SASOS) Unikernel BareMetal References Bibliography External links . . A research exokernel. . A research exokernel. . A commercial exokernel. . A research exokernel. . The GNU exokernel. Operating system kernels Microkernels it:Kernel#Esokernel

Operating System (OS)

A/ROSE A/ROSE (the Apple Real-time Operating System Environment) is a small embedded operating system that runs on Apple Computer's "Macintosh Coprocessor Platform", an expansion card for the Apple Macintosh. The idea was to offer a single "overdesigned" hardware platform on which third party vendors could build practically any product, reducing the otherwise heavy workload of developing a NuBus-based expansion card. However, the MCP cards were fairly expensive, limiting the appeal of the concept. A/ROSE saw very little use, apparently limited solely to Apple's own networking cards for serial I/O, Ethernet, Token Ring and Twinax. GreenSpring Computers developed the RM1260, which is an IndustryPack (IP) carrier card with a 68000 CPU running A/ROSE and is intended for the data acquisition market. History A/ROSE and the MCP originally came about in August 1987 during the development of the Macintosh II. While working on various networking products for the new system, the developers realized that the existing classic Mac OS would make any "serious" card difficult to create, due to large latencies and the difficulty of writing complex device drivers. Their solution was to make an "intelligent" NuBus card that was essentially an entire computer on a card, containing its own Motorola 68000 processor, working space in RAM mirrored in the main system, and its own basic operating system. The first version of the system was ready for use in February 1988. A/ROSE was internally called MR-DOS (Multitasking Realtime Distributed Operating System), but Microsoft (developer of MS-DOS) did not appreciate the name and put pressure on Apple to change its name. Eric M. Trehus, a QA engineer on the Token Ring card that ran A/ROSE reportedly said "A/ROSE by any other name is still MR-DOS." A/ROSE is infamous for its esoteric purpose, which is generally not understood by Mac end users, as well as for causing many Mac emulators, such as Basilisk II, to produce a system error at boot time. Overview A/ROSE itself is very small, the kernel using only 6 KB, and the operating system as a whole about 28 KB. A/ROSE supports pre-emptive multitasking with round-robin task scheduling with a 110 microsecond context switch time and only 20 microseconds of latency (guaranteed interrupt response time). The system's task is primarily to move data around and start and stop tasks on the cards, and the entire API contains only ten calls. A/ROSE is a message passing system, and the main calls made by programs running under it are Send() and Receive(). Messages are short, including only 24 bytes of user data, and sent asynchronously. To find the appropriate endpoint, A/ROSE includes a name server that allows the applications to bind their names to their task IDs, allowing them to move in the system and be found dynamically. The OS also supported a number of routines for finding, starting and stopping tasks on other cards, one of those "cards" being the host computer. To coordinate communications and provide a mechanism for talking with the host's CPU, a cut-down copy of A/ROSE also ran inside the Mac OS in the form of a system extension, or "INIT", known as "Prep" (which should not be confused with the later PReP hardware standard). Device drivers for A/ROSE cards were also written as INITs and started up automatically. After starting, they find the Prep stub and use the normal A/ROSE communications channel it provides to communicate with the cards. For instance, the Apple TokenTalk NB card installs its driver as an INIT, and optionally installs the Prep stub, assuming it had not been installed before. On startup the driver finds the Prep stub and asks it to enumerate the TokenTalk cards installed in the machine, and optionally uploads code or settings to them. From that point on, Prep handles the communications with the card, handing off the results to the TokenTalk driver. References External links Inside the Macintosh Coprocessor Platform and A/ROSE Embedded operating systems Apple Inc. software Apple Inc. operating systems 1988 software

Operating System (OS)

Comparison of BSD operating systems There are a number of Unix-like operating systems based on or descended from the Berkeley Software Distribution (BSD) series of Unix variant options. The three most notable descendants in current use are FreeBSD, OpenBSD, and NetBSD, which are all derived from 386BSD and 4.4BSD-Lite, by various routes. Both NetBSD and FreeBSD started life in 1993, initially derived from 386BSD, but in 1994 migrating to a 4.4BSD-Lite code base. OpenBSD was forked from NetBSD in 1995. Other notable derivatives include DragonFly BSD, which was forked from FreeBSD 4.8, and Apple Inc.'s iOS and macOS, with its Darwin base including a large amount of code derived from FreeBSD. Most of the current BSD operating systems are open source and available for download, free of charge, under the BSD License, the most notable exceptions being macOS and iOS. They also generally use a monolithic kernel architecture, apart from macOS, iOS, and DragonFly BSD which feature hybrid kernels. The various open source BSD projects generally develop the kernel and userland programs and libraries together, the source code being managed using a single central source repository. In the past, BSD was also used as a basis for several proprietary versions of UNIX, such as Sun's SunOS, Sequent's Dynix, NeXT's NeXTSTEP, DEC's Ultrix and OSF/1 AXP (which became the now discontinued Tru64 UNIX). Parts of NeXT's software became the foundation for macOS which, together with iOS, is among the most commercially successful BSD variants in the general market. Aims and philosophies FreeBSD FreeBSD aims to make an operating system usable for any purpose. It is intended to run a wide variety of applications, be easy to use, contain cutting edge features, and be highly scalable on very high load network servers. FreeBSD is free software, and the project prefers the FreeBSD license. However, they sometimes accept non-disclosure agreements (NDAs) and include a limited number of nonfree hardware abstraction layer (HAL) modules for specific device drivers in their source tree, to support the hardware of companies who do not provide purely libre drivers (such as HALs to program software-defined radios so that vendors do not share their nonfree algorithms). To maintain a high level of quality and provide good support for "production quality commercial off-the-shelf (COTS) workstation, server, and high-end embedded systems", FreeBSD focuses on a narrow set of architectures. A significant focus of development since 2000 has been fine-grained locking and SMP scalability. From 2007 on, most of the kernel was fine-locked and scaling improvements started to be seen. Other recent work includes Common Criteria security functionality, such as mandatory access control and security event audit support. Derivatives: TrueNAS/FreeNAS – a network-attached storage (NAS) operating system based on FreeBSD. FuryBSD – a FreeBSD-based operating system, founded after Project Trident decided to build on Void Linux instead of TrueOS. Discontinued in October 2020. GhostBSD – a FreeBSD-based operating system with OpenRC and OS packages. Junos OS – a FreeBSD-based nonfree operating system distributed with Juniper Networks hardware. NomadBSD – a persistent live system for USB flash drives, based on FreeBSD. ClonOS – virtual hosting platform/appliance based on FreeBSD. pfSense – an open source firewall/router computer software distribution based on FreeBSD. OPNsense – an open source firewall/router computer software distribution based on FreeBSD. BSDRP – BSD Router Project: Open Source Router Distribution based on FreeBSD. HardenedBSD – HardenedBSD is a security-enhanced fork of FreeBSD. StarBSD – is a Unix-like, server-oriented operating system based on FreeBSD for Mission-Critical Enterprise Environment. TrueOS (previously PC-BSD) – was a FreeBSD based server operating system, previously a desktop operating system. The project was officially discontinued in May 2020. XigmaNAS – a network-attached storage (NAS) server software with a dedicated management web interface. helloSystem - a GUI-focused system with a macOS interface. NetBSD NetBSD aims to provide a freely redistributable operating system that professionals, hobbyists, and researchers can use in any manner they wish. The main focus is portability, through the use of clear distinctions between machine-dependent and machine-independent code. It runs on a wide variety of 32-bit and 64-bit processor architectures and hardware platforms, and is intended to interoperate well with other operating systems. NetBSD places emphasis on correct design, well-written code, stability, and efficiency. Where practical, close compliance with open API and protocol standards is also aimed for. In June 2008, the NetBSD Foundation moved to a two-clause BSD license, citing changes at UCB and industry applicability. NPF is a project spawned by NetBSD. Derivatives: OS108 – system with graphical desktop environment based on NetBSD. OpenBSD OpenBSD is a security-focused BSD known for its developers' insistence on extensive, ongoing code auditing for security and correct functionality, a "secure by default" philosophy, good documentation, and adherence to strictly open source licensing. The system incorporates numerous security features that are absent or optional in other versions of BSD. The OpenBSD policy on openness extends to hardware documentation and drivers, since without these, there can be no trust in the correct operation of the kernel and its security, and vendor software bugs would be hard to resolve. OpenBSD emphasizes very high standards in all areas. Security policies include disabling all non-essential services and having sane initial settings; and integrated cryptography (originally made easier due to relaxed Canadian export laws relative to the United States), full public disclosure of all security flaws discovered; thoroughly auditing code for bugs and security issues; various security features, including the W^X page protection technology and heavy use of randomization to mitigate attacks. Coding approaches include an emphasis on searching for similar issues throughout the code base if any code issue is identified. Concerning software freedom, OpenBSD prefers the BSD or ISC license, with the GPL acceptable only for existing software which is impractical to replace, such as the GNU Compiler Collection. NDAs are never considered acceptable. In common with its parent, NetBSD, OpenBSD strives to run on a wide variety of hardware. Where licenses conflict with OpenBSD's philosophy, the OpenBSD team has re-implemented major pieces of software from scratch, which have often become the standard used within other versions of BSD. Examples include the pf packet filter, new privilege separation techniques used to safeguard tools such as tcpdump and tmux, much of the OpenSSH codebase, and replacing GPL licensed tools such as diff, grep and pkg-config with ISC or BSD licensed equivalents. OpenBSD prominently notes the success of its security approach on its website home page. , only two vulnerabilities have ever been found in its default install (an OpenSSH vulnerability found in 2002, and a remote network vulnerability found in 2007) in a period of almost 22 years. According to OpenBSD expert Michael W. Lucas, OpenBSD "is widely regarded as the most secure operating system available anywhere, under any licensing terms." OpenBSD has spawned numerous child projects such as OpenSSH, OpenNTPD, OpenBGPD, OpenSMTPD, PF, CARP, and LibreSSL. Many of these are designed to replace restricted alternatives. Derivatives: LibertyBSD – Aimed to be a 'deblobbed' version of OpenBSD. There are a number of reasons as to why blobs can be problematic, according to the project. LibertyBSD began going through the process to become Free Software Foundation FSDG certified, but ultimately never was accepted. LibertyBSD is no longer actively developed, and the project page directs people instead to HyperbolaBSD. DragonFly BSD DragonFly BSD aims to be inherently easy to understand and develop for multi-processor infrastructures. The main goal of the project, forked from FreeBSD 4.8, is to radically change the kernel architecture, introducing microkernel-like message passing which will enhance scaling and reliability on symmetric multiprocessing (SMP) platforms while also being applicable to NUMA and clustered systems. The long-term goal is to provide a transparent single system image in clustered environments. DragonFly BSD originally supported both the IA-32 and x86-64 platforms, however support for IA-32 was dropped in version 4.0. Matthew Dillon, the founder of DragonFly BSD, believes supporting fewer platforms makes it easier for a project to do a proper, ground-up symmetric multiprocessing implementation. Popularity In September 2005, the BSD Certification Group, after advertising on a number of mailing lists, surveyed 4,330 BSD users, 3,958 of whom took the survey in English, to assess the relative popularity of the various BSD operating systems. About 77% of respondents used FreeBSD, 33% used OpenBSD, 16% used NetBSD, 2.6% used Dragonfly, and 6.6% used other (potentially non-BSD) systems. Other languages offered were Brazilian and European Portuguese, German, Italian, and Polish. Note that there was no control group or pre-screening of the survey takers. Those who checked "Other" were asked to specify that operating system. Because survey takers were permitted to select more than one answer, the percentages shown in the graph, which are out of the number survey of participants, add up to greater than 100%. If a survey taker filled in more than one choice for "other", this is still only counted as one vote for other on this chart. Another attempt to profile worldwide BSD usage is the *BSDstats Project, whose primary goal is to demonstrate to hardware vendors the penetration of BSD and viability of hardware drivers for the operating system. The project collects data monthly from any BSD system administrators willing to participate, and currently records the BSD market share of participating FreeBSD, OpenBSD, NetBSD, DragonflyBSD, Debian GNU/kFreeBSD, TrueOS, and MirBSD systems. In 2020, a new independent project was introduced to collect statistics with the goal of significantly increasing the number of observed parameters. DistroWatch, well known in the Linux community and often used as a rough guide to free operating system popularity, publishes page hits for each of the Linux distributions and other operating systems it covers. As of 27 March 2020, using a data span of the last six months it placed FreeBSD in 21st place with 452 hits per day, GhostBSD in 51st place with 243 hits, TrueOS in 54th place with 182 hits per day, DragonflyBSD in 75th place with 180 hits, OpenBSD in 80th place with 169 hits per day and NetBSD in 109th place with 105 hits per day. Names, logos, slogans The names FreeBSD and OpenBSD are references to software freedom: both in cost and open source. NetBSD's name is a tribute to the Internet, which brought the original developers together. The first BSD mascot was the BSD daemon, named after a common type of Unix software program, a daemon. FreeBSD still uses the image, a red cartoon daemon named Beastie, wielding a pitchfork, as its mascot today. In 2005, after a competition, a stylized version of Beastie's head designed and drawn by Anton Gural was chosen as the FreeBSD logo. The FreeBSD slogan is "The Power to Serve." The NetBSD flag, designed in 2004 by Grant Bissett, is inspired by the original NetBSD logo, designed in 1994 by Shawn Mueller, portraying a number of BSD daemons raising a flag on top of a mound of computer equipment. This was based on a World War II photograph, Raising the Flag on Iwo Jima. The Board of Directors of The NetBSD Foundation believed this was too complicated, too hard to reproduce and had negative cultural ramifications and was thus not a suitable image for NetBSD in the corporate world. The new, simpler flag design replaced this. The NetBSD slogan is "Of course it runs NetBSD", referring to the operating system's portability. Originally, OpenBSD used the BSD daemon as a mascot, sometimes with an added halo as a distinguishing mark, but OpenBSD later replaced its BSD daemon with Puffy. Although Puffy is usually referred to as a pufferfish, the spikes on the cartoon images give him a closer likeness to the porcupinefish. The logo is a reference to the fish's defensive capabilities and to the Blowfish cryptography algorithm used in OpenSSH. OpenBSD also has a number of slogans including "Secure by default", which was used in the first OpenBSD song, "E-railed", and "Free, Functional & Secure", and OpenBSD has released at least one original song with every release since 3.0. The DragonFly BSD logo, designed by Joe Angrisano, is a dragonfly named Fred. A number of unofficial logos by various authors also show the dragonfly or stylized versions of it. DragonFly BSD considers itself to be "the logical continuation of the FreeBSD 4.x series." FireflyBSD has a similar logo, a firefly, showing its close relationship to DragonFly BSD. In fact, the FireflyBSD website states that proceeds from sales will go to the development of DragonFly BSD, suggesting that the two may in fact be very closely related. PicoBSD's slogan is "For the little BSD in all of us," and its logo includes a version of FreeBSD's Beastie as a child, showing its close connection to FreeBSD, and the minimal amount of code needed to run as a Live CD. A number of BSD OSes use stylized version of their respective names for logos. This includes macOS, TrueOS, GhostBSD, DesktopBSD, ClosedBSD, and MicroBSD. TrueOS's slogan is "Personal computing, served up BSD style!", GhostBSD's "A simple, secure BSD served on a Desktop." DesktopBSD's "A Step Towards BSD on the Desktop." MicroBSD's slogan is "The small secure unix like OS." MirOS's site collects a variety of BSD mascots and Tux, the Linux mascot, together, illustrating the project's aim of supporting both BSD and Linux kernels. MirOS's slogan is "a wonderful operating system for a world of peace." General information See also List of BSD operating systems BSD license Comparison of open source operating systems Comparison of operating systems Notes and references Other sources A semi-official download page. Comparison BSD operating systems

Operating System (OS)

Sinclair QDOS QDOS is the multitasking operating system found on the Sinclair QL personal computer and its clones. It was designed by Tony Tebby whilst working at Sinclair Research, as an in-house alternative to 68K/OS, which was later cancelled by Sinclair, but released by original authors GST Computer Systems. Its name is not regarded as an acronym and sometimes written as Qdos in official literature (see also the identically-pronounced word kudos). QDOS was implemented in Motorola 68000 assembly language, and on the QL, resided in 48 KB of ROM, consisting of either three 16 KB EPROM chips or one 32 KB and one 16 KB ROM chip. These ROMs also held the SuperBASIC interpreter, an advanced variant of BASIC programming language with structured programming additions. This also acted as the QDOS command-line interpreter. Facilities provided by QDOS included management of processes (or "jobs" in QDOS terminology), memory allocation, and an extensible "redirectable I/O system", providing a generic framework for filesystems and device drivers. Very basic screen window functionality was also provided. This, and several other features, were never fully implemented in the released versions of QDOS, but were improved in later extensions to the operating system produced by Tebby's own company, QJUMP. Rewritten, enhanced versions of QDOS were also developed, including Laurence Reeves' Minerva and Tebby's SMS2 and SMSQ/E. The last is the most modern variant and is still being improved. Versions QDOS versions were identified by numerical version numbers. However, the QL firmware ROMs as a whole (including SuperBASIC) were given two- or three-letter alphabetic identifiers (returned by the SuperBASIC function VER$). The following version of QDOS were released (dates are estimated first customer shipments): 0.08: the last pre-production version. 1.00: corresponded to the FB version QL ROMs, released in April 1984. 1.01: corresponded to the PM version ROMs. This was faster and had improved Microdrive support. 1.02: corresponded to the AH ROM version released in June 1984. This fixed many bugs and was the first ROM version to be produced in quantity. 1.03: included in ROM versions JM and TB; a minor bug-fix release issued in late 1984. 1.10: corresponded to the JS and JSU (US export version) ROMs, released in early 1985. This was the last version used in QLs manufactured for the UK market. 1.13: corresponding to the MGx series of ROM versions for European export markets. Included a significant number of bug fixes. The following localised versions of the MG firmware are known to exist: MGE: Spanish MGF: French MGG: German MGI: Italian MGS: Swedish The localised versions of QDOS were identified by the "." in the version number being replaced by the ROM version suffix letter used to identify the territory, e.g. the MGE ROMs contained QDOS version 1E13. All MG firmware versions shared the same bottom 32 KB ROM chip. Qdos 1.13 was also reported to be included in a Greek localised ROM version, known as ΣFP (marked on the ROMs as EFP). Notes References Andrew Pennell (1985). The Sinclair QDOS Companion: a guide to the QL operating system. London: Sunshine Books. Simon Goodwin. "Bugging the ROM", Sinclair QL World, August 1987 QL History FAQ: Firmware External links The official SMSQ/E site Source Code, binaries and documentation QDOS Internals Dokuwiki established by Norman Dunbar QL ROM versions list by Dilwyn Jones QL/E The QL runtime Environment Amiga implementation Discontinued operating systems Sinclair Research Assembly language software 68k architecture 1984 software

Operating System (OS)

Z80-RIO The Z80 Operating System with Relocatable Modules and I/O Management (Z80-RIO) is a general-purpose operating system developed by Zilog in the late 1970s for various computer systems including the Z80 Micro Computer System (MCZ-1) series and the Z80 Development System (ZDS). The MCZ systems were primarily used for software development and automation solutions. RIO was designed to facilitate the development and integration of user's programs into a production environment. Features The system provides a modest environment with a minimum of system support and an enhanced environment. The modest environment provides a program debugger with file manipulation capability, a floppy disk driver (supporting up to eight disk drives), and a basic console driver with provision for paper tape operation. The enhanced environment provides access to the RIO Executive and to system support utilities such as the Zilog Floppy Disk File System (ZDOS), and the Zilog Hard Disk File System (DFS). It also provides access to a number of disk-resident software such a text editor, macro assembler, and linker. Commands The following list of commands are supported by Z80-RIO. ACTIVATE ALLOCATE ASM BRIEF CAT CLOSE COMPARE COPY COPY.DISK COPYSD DATE DEACTIVATE DEALLOCATE DEBUG DEFINE DELETE DISK.FORMAT DISK.REPAIR DISK.STATUS DISPLAY DO DUMP ECHO EDIT ERROR ERRORS EXTRACT FORCE FORMAT HELP IMAGE INITIALIZE LADT LINK MASTER MEMORY MOVE PAUSE RELEASE RENAME RESTORE_TABS SAVE_TABS SET STATUS VERBOSE XEQ Clones UDOS, a Z80-RIO compatible clone by VEB Robotron, was available for a number of computers by the same company, such as the A 5120 or the PC 1715, which were based on the U880 processor (the latter being a clone of Zilog's Z80). UDOS was also one of the operating systems available for the P8000, a microcomputer system developed in 1987 by the VEB Elektro-Apparate-Werke Berlin-Treptow „Friedrich Ebert“ (EAW) in the German Democratic Republic (DDR, East Germany). See also Federico Faggin References External links Zilog website RIO & PLZ reloaded Les Bird's MCZ utilities and RIO OS disk images Discontinued operating systems Disk operating systems Microcomputer software Proprietary operating systems Z80

Operating System (OS)

UberStudent UberStudent is a free and open-source computer operating system and collection of programs aimed especially toward higher education and secondary students and their teachers and schools. The lead developer of the Linux distribution placed the project on hold in May 2019 due to his son being amid a protracted battle with Acute lymphoblastic leukemia. Dubbing itself "Linux for Learners", UberStudent describes itself as "a cohesive academic success curriculum integrated into an installable, easy-to-use, and full-featured learning platform" aimed at increasing overall student learning and academic computer literacy, and lifelong computer fluency. Its additional aim is to increase the adoption of free and open-source computing platforms, like itself, within higher education and secondary schools. It is designed around a "core academic skills approach to student success," which it describes as "the research and writing, reading, studying, and self-management skills that are essential to all students regardless of their academic major." UberStudent's current release is 4.3, dubbed Heraclitus. The distribution uses its own dedicated software repository. It can be run from a live CD, USB flash drive, or installed onto a computer's hard drive from either of those mediums. Support for the last published version, UberStudent 4.3, based on Ubuntu 14.04, ended in May 2019. As of May 26, 2019, the distribution's website went offline, while the domains are still owned by Uberstudent's lead developer, Stephen Ewen. Prior that date and afterward, per official statements made by Ewen on Uberstudent's official webpage, and added to in its lone public internet outlet afterward, Facebook. According to him, the project has been placed on hold, not discontinued or abandoned, because his son has been in a protracted battle with Acute lymphoblastic leukemia, which he detailed. Origin and design UberStudent's founder and lead developer is Stephen Ewen, a U.S.-based educator who specializes in postsecondary literacy, academic success strategies, and educational technology. He began UberStudent, he has said, as "a way to place a set of smart and dedicated computing tools, and just the right amount of support, into the hands of students, whether currently within higher education or preparing for it in secondary school." His stated goal through UberStudent is for students to "learn to really excel at the core skills and habits they need to become everything they can academically be, and on into professional life." Ewen has stated that UberStudent is, in part, inspired by his own experiences achieving top academic performance with the assistance of educational technology. Ewen has described UberStudent's overarching design philosophy as one that provides a "unified system for learning, doing, and teaching academic success". Within this, he has said that UberStudent takes what he calls a "core academic skills" approach, which he has delineated as "the skills in research and writing, studying, and self-management required of students across all academic majors". He has stated that UberStudent can be "easily extended" for specific majors via additional software. Ewen has additionally asserted that, in part due to UberStudent's open source and cross-platform nature, as well as its Unix-like base, it is geared to produce "computer fluency" among its users as a "more or less natural outcome". Ewen has argued that academic institutions can increase both their student learning outcomes and economic efficiency by more broadly adopting open source application and system software for everyday student academic computing needs. He has additionally argued for academic institutions to increase their involvement in developing open source tools, such as UberStudent, citing successes such as the bibliographic manager Zotero by George Mason University, included among UberStudent's set of core academic programs. Software and system Nearly all of UberStudent's software is free and open-source and its core programs cross-platform so its adopters can avoid vendor lock-in, whether with Windows, Mac OS X, or Linux. The tech review site Dedoimedo reviewed UberStudent as containing a "superb" collection of "smartly selected" programs, "probably the best when it comes to serious work", with each "stitched into the fabric of the operating system". Tech columnist Jack Wallen said UberStudent "contains so many education-specific tools you will be spending your first days with it just marveling at what the developers have packed into one single operating system." UberStudent's core programs for academic work are clustered within an applications menu entry, Education, where they are organized by sub-categories, including for Reading, Research and Writing, Self-Management, Study Aids, Subjects, and Utilities, which themselves have sub-categories. In addition to its academic-specific application set, reviewers have noted UberStudent's inclusion of templates for academic work and "tons" of on-board how-to guides as "welcome additions" that are "often missing" from other operating systems. UberStudent also contains a full range of student-oriented programs in the Multimedia, Games, Graphics, Internet, and several other categories. Within a separate menu, it contains select cloud computing applications that have been described as containing additions "you don't often see elsewhere". Within its stated intent to couple user-friendliness with security and stability, UberStudent production releases are based on Xubuntu Long Term Stable releases, which stems from the Debian branch of Linux. UberStudent also includes numerous self-developed programs, as well as its own Update Manager and the deb file format to manage and update its platform. Editions UberStudent main editions are distributed as a DVD image or pre-made disc. The full edition features the Xfce desktop environment, and the lightweight edition the LXDE desktop environment. The LXDE lightweight edition is greatly scaled down and is intended solely "to re-invigorate low-specification or older computers" and fits on a single CD. Criticisms of competing desktop environments Amid his decision to feature Xfce in UberStudent full editions, Ewen stated that "UberStudent must prefer stability, dependability, and traditional usability over the novel when it comes to such a major thing as the basic desktop environments it uses; and it will." GNOME 3, Ubuntu Unity During UberStudent's 2.0 release cycle, Ewen criticized the designs of both the Ubuntu Unity and GNOME 3 Shell Linux desktop environments as hindrances to student academic computing productivity. In a 2011 April Fools' Day satire, he announced an "UberStudent Dumbed Down Edition" featuring the GNOME 3 Shell. Pointing to what he called "the enforced helplessness" leading to "learned helplessness" that he says the GNOME 3 developers designed into their new desktop environment, he stated that the intent behind the spoof UberStudent edition was to "obscure what is not obvious and easy so it can be continually avoided" by students and thus never learned. In a May 2011 interview, Ewen expanded his criticisms of Unity and GNOME 3 by citing specific usability issues, and stated that UberStudent had no plans to adopt either Unity or the GNOME 3 Shell. Cinnamon Amid UberStudent's 3.0 release cycle, Ewen criticized the Cinnamon desktop environment, developed by Linux Mint, pointing out what he called "major shortcomings" in Cinnamon, which he stipulated as its failure to honor certain fundamental freedesktop.org standards. Ewen stated that, while the desktop environment holds promise, "Cinnamon as of its full May 2013 version 1.8 release is actually beta-quality software." As such, he characterized Cinnamon as "not at all yet suited for a serious and stable workstation. Releases and naming According to Ewen, "UberStudent dubs each of its major releases after a famous historical thinker", a practice he describes as "only fitting" in light of UberStudent's educational mission. So far, the thinkers have been Greek and Roman. UberStudent's version 0.9, the first beta, was released on 15 January 2010 and named after Thales. Version 1.0, released on 15 July 2010, was named after Cicero. 1.0 also had a brief pre-release edition, once inadvertently reviewed as the release edition. UberStudent 1.0 Cicero Lightweight Edition was released on 4 September 2010 and inherited the name Cicero from the full edition. UberStudent 2.0 was dubbed "Plato," UberStudent 3.0 was dubbed "Aristotle," and the 4.0 release "Socrates". The current release, 4.3, is dubbed "Heraclitus." 5.0 is being delayed due to Ewen's son being diagnosed with Acute lymphoblastic leukemia. Reception UberStudent has been described by reviewers as "highly in tune with student needs", "loaded with student-friendly tools and customizations", "perfect for the higher education environment", succeeding at its aims "with aplomb, elegance, and power", "a smart pick for getting your actual schoolwork done", and "fantastic and delicious". It received a positive review in The Chronicle of Higher Education, which cited UberStudent's completeness for doing core academic work, user-friendliness, and free and open-source nature. Sixty days after UberStudent's official 15 July 2010 release of UberStudent 1.0 Cicero Full Edition, its first non-beta, DistroWatch ranked it the most popular Linux distribution for education worldwide and the 32nd most popular overall out of the 316 varied distributions tracked by the organization. Weeks after the 4.1 release, it ranked as the fifth-most popular Linux distribution in the world. See also List of third-party Ubuntu-based Linux distributions Edubuntu Edtech References External links UberStudent on SourceForge UberStudent at DistroWatch Ubuntu derivatives Educational software Free educational software Educational operating systems Linux distributions

Operating System (OS)

SteamOS SteamOS is a Linux distribution by Valve. It is open source with some closed source components. It is the primary operating system for the Steam Machine gaming platform and Steam Deck hybrid video game console by Valve. The initial versions of SteamOS, versions 1.0 and 2.0, were based on the Debian distribution of Linux. SteamOS was built to support streaming of video games from one personal computer to the one running SteamOS within the same network, though the operating system can support standalone systems and was intended to be used as part of Valve's Steam Machine platform. With SteamOS, Valve encouraged developers to incorporate Linux compatibility into their releases to better support Linux gaming options. In July 2021, Valve announced the Steam Deck, a hybrid video game console. It runs SteamOS 3.0, which is based on the Arch Linux distribution with a KDE Plasma 5 desktop, rather than the Debian base used for earlier versions of SteamOS. Features SteamOS is designed primarily for playing video games away from a PC (such as from the couch in one's living room) by providing a console-like experience using generic PC hardware that can connect directly to a television. It can run games natively that have been developed for Linux and purchased from the Steam store. Users are also able to stream games from their Windows, Mac or Linux computers to one running SteamOS, and it incorporates the same family sharing and restrictions as Steam on the desktop. Valve claims that it has "achieved significant performance increases in graphics processing" through SteamOS. The operating system is open source, allowing users to build on or adapt the source code, though the actual Steam client is closed. Since SteamOS is solely for playing games without a mouse or keyboard, it does not have many built-in functions beyond web browsing and playing games; for example, there is no file manager or image viewer installed by default. Users can, however, access the GNOME desktop environment and perform tasks such as installing other software. Though the OS does not currently support streaming services, Valve historically considered integration with Spotify and Netflix. However, Steam does have full-length films from indie movie makers available from their store. The OS natively supports Nvidia, Intel, and AMD graphics processors. Valve stated that it has added support for movies, television, and music to SteamOS. However, video content is only available from Steam's store, which has a small number of films. Music playback only supports local music collections. In October 2015, an update allowed Netflix and other DRM protected content to function in the native built-in browser. The current system hardware requirements for default SteamOS installations include: Intel or AMD 64-bit capable processor At least 4 GB of RAM At least 200 GB on one’s hard disk NVIDIA (Fermi graphics cards or newer), Intel, or AMD graphics card (RADEON 8500 or newer) USB port for installation UEFI boot support A custom installer method is also available, which can require additional configuration steps. This method allows for smaller hard-disk sizes. There is also an ISO image installer that supports legacy BIOS motherboard. The installers can be sourced through Valve's repository. History During a panel at LinuxCon on September 16, 2013, Valve co-founder and executive director Gabe Newell stated that he believed "Linux and open source are the future of gaming", going on to say that the company was aiding game developers who want to make games compatible with Linux, and that they would be making an announcement the following week related to introducing Linux into the living room. On September 20, 2013, Valve posted a statement on its website titled The Steam Universe is Expanding in 2014 which teased three new announcements related to "even more ways to connect the dots for customers who want Steam in the living-room". The first announcement was made on September 23 as SteamOS, with Valve saying they had "come to the conclusion that the environment best suited to delivering value to customers is an operating system built around Steam itself". A large focus of the reveal was the openness of the operating system, with it being announced that users would be able to alter or replace any part of the software, and that it would be free. In October 2013, Valve announced Steam Dev Days; a two-day developer conference where video game developers could test and provide feedback on SteamOS and Steam Machines. In October 2013, Nvidia also announced their collaboration with Valve to support SteamOS with the help of a development suite called Nvidia GameWorks which incorporates PhysX, OptiX, VisualFX and other Nvidia-proprietary APIs and implementations thereof. In November 2013, Valve confirmed that they would not be making any exclusive games for SteamOS, and discouraged other developers from doing so, as it goes against their philosophy of selling games wherever customers are. In December, Valve announced that a beta version of SteamOS would be released on December 13, 2013. When this beta version released, Valve encouraged customers unfamiliar with Linux to wait until 2014. In mid-October 2015, preorders of the Steam Controller, Steam Link, and Alienware branded Steam Machines became available. The official release date for Steam Machines was on November 10, 2015. On July 15, 2021, Valve announced the Steam Deck, a brand new handheld PC gaming device. The Steam Deck runs a customized version of Steam OS 3.0 that is based upon Arch Linux, with the desktop mode being powered by KDE Plasma. The decision to move from Debian to Arch Linux was based on the different update schedule for these distributions. Debian, geared for server configurations, has its core software update in one large package with intermediate patches for known bug and security fixes, while Arch uses a rolling update approach for all parts. Valve found that the rolling update approach would be better suited for the Steam Deck, allowing them to address issues and fixes much faster than Debian would allow. Valve affirmed that SteamOS 3.0 will continue to be freely available, with the intention of allowing other hardware developers to take advantage of it and build similar handheld computing devices like the Deck. Releases Performance In December 2013, Phoronix compared three Nvidia graphics cards on SteamOS and Windows 8.1. Overall, Nvidia's proprietary Linux graphics driver delivered performance comparable to that of the Windows drivers due to the platforms’ largely shared codebase. In January 2014, GameSpot compared the performance of three games (Dota 2, Left 4 Dead 2, and Metro: Last Light) running on Windows and SteamOS. With an AMD graphics card, they found that all ran at considerably fewer frames per second on SteamOS, and Left 4 Dead 2 stuttered, which they attributed to a device driver problem. With an Nvidia graphics card, they found that Metro: Last Light ran at a slightly higher frame rate and Dota 2 broke even. With both video card brands, Left 4 Dead 2 and Dota 2 had longer load times on SteamOS. When Steam Machines was officially released in November 2015, Ars Technica compared the rendering performance of cross-platform games on SteamOS and Windows 10 running on the same machine, using average frame-per-second measurements, and found that games rendered between 21% and 58% slower on SteamOS. Ars Technica suggested this might be due to the inexperience of developers optimizing on OpenGL in contrast to DirectX, and believed that the performance might improve with future titles. They noted that their benchmark test, using six games on a single computer, was far from comprehensive. Reception Following SteamOS’ initial announcement, many video game developers expressed enthusiasm. Minecraft creator Markus Persson described it as "amazing news," and Thomas Was Alone developer Mike Bithell called it "encouraging" for indie games. Other developers such as DICE, creators of the Battlefield series, and The Creative Assembly, developers of the Total War series, stated that they may add Linux support for their games following SteamOS’ release. On the operating system front, Gearbox Software head Randy Pitchford expressed a belief that the operating system needed a unique application to attract developers, saying "without that must-buy product driving us all towards this stuff, I expect that the industry at large will watch curiously, but remain largely unaffected." Richard Stallman, former president of the Free Software Foundation, expressed cautious support, but does not condone the use of non-free games or DRM. The SteamOS beta release received mixed reviews. In TechRadar's review Henry Winchester praised the easy to navigate interface and future potential but criticized the hard installation and lack of extra features compared to the Steam software. Eurogamer's Thomas Morgan did not experience installation problems, but commented negatively on the lack of options available for detecting monitor resolutions and audio output, in addition to the lack of games available natively on the operating system. However, he responded well to the user interface, calling it "a positive start". Since then, outlets such as Ars Technica have revisited the SteamOS since its initial debut, offering observations on the platform's growth, pros, and cons. Both Falcon Northwest and Origin PC, computer manufacturers that were planning on offering Steam Machine hardware, opted to not ship a SteamOS-enabled machine in 2015 due to limitations of SteamOS over Windows; Falcon Northwest said they would still consider shipping machines with SteamOS in the future if performance improves. See also Linux gaming References External links 2013 software Arch-based Linux distributions Debian-based distributions Free software operating systems Linux distributions OS X86-64 Linux distributions Game console operating systems 2022 software

Operating System (OS)

VM (operating system) VM (often: VM/CMS) is a family of IBM virtual machine operating systems used on IBM mainframes System/370, System/390, zSeries, System z and compatible systems, including the Hercules emulator for personal computers. The following versions are known: Virtual Machine Facility/370 VM/370, released in 1972, is a System/370 reimplementation of earlier CP/CMS operating system. VM/370 Basic System Extensions Program Product VM/BSE (BSEPP) is an enhancement to VM/370 VM/370 System Extensions Program Product VM/SE (SEPP) is an enhancement to VM/370 that includes the facilities of VM/BSE Virtual Machine/System Product VM/SP, a milestone version, replaces VM/370, VM/BSE and VM/SE. Release 1 added EXEC2 and XEDIT System Product Editor; Release 3 added REXX. Virtual Machine/System Product High Performance Option VM/SP HPO adds additional device support and functionality to VM/SP Virtual Machine/Extended Architecture Migration Aid VM/XA MA is inteended to ease the migration from MVS/370 to MVS/XA by allowing both to run concurrently on the same processor complex. Virtual Machine/Extended Architecture System Facility VM/XA SF is an upgraded VM/XA MA with improved functionality and performance. Virtual Machine/Extended Architecture System Product VM/XA SF is an upgraded VM/XA MA with improved functionality and performance, offered as a replacement for VM/SP HPO on machines supporting S/370-XA. It includes a version of CMS that can run in either S/370 or S/370-XA mode. Virtual Machine/Enterprize Systems Architecture VM/ESA provides the facilities of VM/SP, VM/SP HPO and VM/XA SP. VM/ESA can run in S/370, ESA/370 or ESA/390 mode; it does not support S/370 XA mode. z/VM z/VM, the last version still widely used as one of the main full virtualization solutions for the mainframe market. The CMS in the name refers to the Conversational Monitor System, a component of the product that is a single-user operating system that runs in a virtual machine and provides conversational time-sharing in VM. Overview The heart of the VM architecture is the Control Program or hypervisor abbreviated CP, VM-CP and sometimes, ambiguously, VM. It runs on the physical hardware, and creates the virtual machine environment. VM-CP provides full virtualization of the physical machine – including all I/O and other privileged operations. It performs the system's resource-sharing, including device management, dispatching, virtual storage management, and other traditional operating system tasks. Each VM user is provided with a separate virtual machine having its own address space, virtual devices, etc., and which is capable of running any software that could be run on a stand-alone machine. A given VM mainframe typically runs hundreds or thousands of virtual machine instances. VM-CP began life as CP-370, a reimplementation of CP-67, itself a reimplementation of CP-40. Running within each virtual machine is another operating system, a guest operating system. This might be: CMS (Conversational Monitor System, renamed from the Cambridge Monitor System of CP/CMS). Most virtual machines run CMS, a lightweight, single-user operating system. Its interactive environment is comparable to that of a single-user PC, including a file system, programming services, device access, and command-line processing. (While an earlier version of CMS was uncharitably described as "CP/M on a mainframe", the comparison is an anachronism; the author of CP/M, Gary Kildall, was an experienced CMS user.) GCS (Group Control System), which provides a limited simulation of the MVS API. IBM originally provided GCS in order to run VTAM without a service OS/VS1 virtual machine and VTAM Communications Network Application (VCNA). RSCS V2 also ran under GCS. A mainstream operating system. IBM's mainstream operating systems (i.e. the MVS, DOS/VSE, or TSS/370 families) can be loaded and run without modification. The VM hypervisor treats guest operating systems as application programs with exceptional privileges – it prevents them from directly using privileged instructions (those which would let applications take over the whole system or significant parts of it), but simulates privileged instructions on their behalf. Most mainframe operating systems terminate a normal application which tries to usurp the operating system's privileges. The VM hypervisor can simulate several types of console terminals for the guest operating system, such as the hardcopy line-mode 3215, the graphical 3270 family, and the integrated console on newer System/390 and System Z machines. Another copy of VM. A second level instance of VM can be fully virtualized inside a virtual machine. This is how VM development and testing is done (a second-level VM can potentially implement a different virtualization of the hardware). This technique was used to develop S/370 software before S/370 hardware was available, and it has continued to play a role in new hardware development at IBM. The literature cites practical examples of virtualization five levels deep (see page 28 of VM and the VM Community). Levels of VM below the top are also treated as applications but with exceptional privileges. A copy of the mainframe version of AIX or Linux. In the mainframe environment, these operating systems often run under VM, and are handled like other guest operating systems. (They can also run as 'native' operating systems on the bare hardware.) There was also the short-lived IX/370, as well as S/370 and S/390 versions of AIX (AIX/370 and AIX/ESA). A specialized VM subsystem. Several non-CMS systems run within VM-CP virtual machines, providing services to CMS users such as spooling, interprocess communications, specialized device support, and networking. They operate behind the scenes, extending the services available to CMS without adding to the VM-CP control program. By running in separate virtual machines, they receive the same security and reliability protections as other VM users. Examples include: RSCS (Remote Spooling and Communication Subsystem, aka VNET) – communication and information transfer facilities between virtual machines and other systems RACF (Resource Access Control Facility) — a security system Shared File System (SFS), which organizes shared files in a directory tree (the servers are commonly named "VMSERVx" VTAM (Virtual Telecommunications Access Method) – a facility that provides support for a Systems Network Architecture network PVM (VM/Pass-Through Facility) – a facility that provides remote access to other VM systems TCPIP, SMTP, FTPSERVE, PORTMAP, VMNFS – a set of service machines that provide TCP/IP networking to VM/CMS Db2 Server for VM – a SQL database system, the servers are often named similarly to "SQLMACH" and "SQLMSTR" DIRMAINT – A simplified user directory management system (the directory is a listing of every account on the system, including virtual hardware configuration, user passwords, and minidisks). A user-written or modified operating system, such as National CSS's CSS or Boston University's VPS/VM. Hypervisor interface IBM coined the term hypervisor for the 360/65 and later used it for the DIAG handler of CP-67. The Diagnose instruction ('83'x—no mnemonic) is a privileged instruction originally intended by IBM to perform "built-in diagnostic functions, or other model-dependent functions." IBM repurposed DIAG for "communication between a virtual machine and CP." The instruction contains two four-bit register numbers, called Rx and Ry, which can "contain operand storage addresses or return codes passed to the DIAGNOSE interface," and a two-byte code "that CP uses to determine what DIAGNOSE function to perform." A few of the available diagnose functions are listed below. CMS use of DIAGNOSE At one time, CMS was capable of running on a bare machine, as a true operating system (though such a configuration would be unusual). It now runs only as a guest OS under VM. This is because CMS relies on a hypervisor interface to VM-CP, to perform file system operations and request other VM services. This paravirtualization interface: Provides a fast path to VM-CP, to avoid the overhead of full simulation. Was first developed as a performance improvement for CP/CMS release 2.1, an important early milestone in CP's efficiency. Uses a non-virtualized, model-dependent machine instruction as a signal between CMS and CP: DIAG (diagnose). Minidisks CMS and other operating systems often have DASD requirements much smaller than the sizes of actual volumes. For this reason CP allows an installation to define virtual disks of any size up to the capacity of the device. For CKD volumes, a minidisk must be defined in full cylinders. A minidisk has the same attributes as the underlying real disk, except that it is usually smaller and the beginning of each minidisk is mapped to cylinder or block 0. The minidisk may be accessed using the same channel programs as the real disk. A minidisk that has been initialized with a CMS file system is referred to as a CMS minidisk, although CMS is not the only system that can use them. It is common practice to define full volume minidisks for use by such guest operating systems as z/OS instead of using DEDICATE to assign the volume to a specific virtual machine. In addition, "full-pack links" are often defined for every DASD on the system, and are owned by the MAINT userid. These are used for backing up the system using the DASD Dump/Restore program, where the entire contents of a DASD are written to tape (or another DASD) exactly. Shared File System VM/SP Release 6 introduced the Shared File System which vastly improved CMS file storage capabilities. The CMS minidisk file system does not support directories (folders) at all, however, the SFS does. SFS also introduces more granular security. With CMS minidisks, the system can be configured to allow or deny users read-only or read-write access to a disk, but single files cannot have the same security. SFS alleviates this, and vastly improves performance. The SFS is provided by service virtual machines. On a modern VM system, there are usually three that are required: VMSERVR, the "recovery machine" that does not actually serve any files; VMSERVS, the server for the VMSYS filepool; and VMSERVU, the server for the VMSYSU (user) filepool. The file pool server machines own several minidisks, usually including a CMS A-disk (virtual device address 191, containing the file pool configuration files), a control disk, a log disk, and any number of data disks that actually store user files. With modern VM versions, most of the system can be installed to SFS, with the few remaining minidisks being the ones absolutely necessary for the system to start up, and the ones being owned by the filepool server machines. If a user account is configured to only use SFS (and does not own any minidisks), the user's A-disk will be FILEPOOL:USERID. and any subsequent directories that the user creates will be FILEPOOL:USERID.DIR1.DIR2.DIR3 where the equivalent UNIX file path is /dir1/dir2/dir3. The file pool server machines also serve a closely related filesystem: the Byte File System. BFS is used to store files on a UNIX-style filesystem. Its primary use is for the VM OpenExtensions POSIX environment for CMS. History The early history of VM is described in the articles CP/CMS and History of CP/CMS. VM/370 is a reimplementation of CP/CMS, and was made available in 1972 as part of IBM's System/370 Advanced Function announcement (which added virtual memory hardware and operating systems to the System/370 series). Early releases of VM through VM/370 Release 6 continued in open source through 1981, and today are considered to be in the public domain. This policy ended in 1977 with the chargeable VM/SE and VM/BSE upgrades and in 1980 with VM/System Product (VM/SP). However, IBM continued providing updates in source form for existing code for many years, although the upgrades to all but the free base required a license. As with CP-67, privileged instructions in a virtual machine cause a program interrupt, and CP simulated the behavior of the privileged instruction. VM remained an important platform within IBM, used for operating system development and time-sharing use; but for customers it remained IBM's "other operating system". The OS and DOS families remained IBM's strategic products, and customers were not encouraged to run VM. Those that did formed close working relationships, continuing the community-support model of early CP/CMS users. In the meantime, the system struggled with political infighting within IBM over what resources should be available to the project, as compared with other IBM efforts. A basic problem with the system was seen at IBM's field sales level: VM/CMS demonstrably reduced the amount of hardware needed to support a given number of time-sharing users. IBM was, after all, in the business of selling computer systems. Melinda Varian provides this fascinating quote, illustrating VM's unexpected success: The marketing forecasts for VM/370 predicted that no more than one 168 would ever run VM during the entire life of the product. In fact, the first 168 delivered to a customer ran only CP and CMS. Ten years later, ten percent of the large processors being shipped from Poughkeepsie would be destined to run VM, as would a very substantial portion of the mid-range machines that were built in Endicott. Before fifteen years had passed, there would be more VM licenses than MVS licenses. A PC DOS version that runs CMS on the XT/370 (and later on the AT/370) is called VM/PC. VM/PC 1.1 was based on VM/SP release 3. When IBM introduced the P/370 and P/390 processor cards, a PC could now run full VM systems, including VM/370, VM/SP, VM/XA, and VM/ESA (these cards were fully compatible with S/370 and S/390 mainframes, and could run any S/370 operating system from the 31-bit era, e.g., MVS/ESA, VSE/ESA). In addition to the base VM/SP releases, IBM also introduced VM/SP HPO (High Performance Option). This add-on (which is installed over the base VM/SP release) improved several key system facilities, including allowing the usage of more than 16 MB of storage (RAM) on supported models (such as the IBM 4381). With VM/SP HPO installed, the new limit was 64 MB; however, a single user (or virtual machine) could not use more than 16 MB. The functions of the spool filesystem were also improved, allowing 9900 spool files to be created per user, rather than 9900 for the whole system. The architecture of the spool filesystem was also enhanced, each spool file now had a unique user ID associated with it, and reader file control blocks were now held in virtual storage. The system could also be configured to deny certain users access to the vector facility (by means of user directory entries). Releases of VM since VM/SP Release 1 supported multiprocessor systems. System/370 versions of VM (such as VM/SP and VM/SP HPO) supported a maximum of two processors, with the system operating in either UP (uniprocessor) mode, MP (multiprocessor) mode, or AP (attached processor) mode. AP mode is the same as MP mode, except the second processor lacks I/O capability. System/370-XA releases of VM (such as VM/XA) supported more. System/390 releases (such as VM/ESA) almost removed the limit entirely, and some modern z/VM systems can have as many as 80 processors. The per-VM limit for defined processors is 64. When IBM introduced the System/370 Extended Architecture on the 3081, customers were faced with the need to run a production MVS/370 system while testing MVS/XA on the same machine. IBM's solution was VM/XA Migration Aid, which used the new Start Interpretive Execution (SIE) instruction to run the virtual machine. SIE automatically handled some privileged instructions and returned to CP for cases that it couldn't handle. The Processor Resource/System Manager (PR/SM) of the later 3090 also used SIE. There were several VM/XA products before it was eventually supplanted by VM/ESA and z/VM. In addition to RSCS networking, IBM also provided users with VTAM networking. ACF/VTAM for VM was fully compatible with ACF/VTAM on MVS and VSE. Like RSCS, VTAM on VM ran under the specialized GCS operating system. However, VM also supported TCP/IP networking. In the late 1980s, IBM produced a TCP/IP stack for VM/SP and VM/XA. The stack supported IPv4 networks, and a variety of network interface systems (such as inter-mainframe channel-to-channel links, or a specialized IBM RT PC that would relay traffic out to a Token Ring or Ethernet network). The stack provided support for Telnet connections, from either simple line-mode terminal emulators or VT100-compatible emulators, or proper IBM 3270 terminal emulators. The stack also provided an FTP server. IBM also produced an optional NFS server for VM; early versions were rather primitive, but modern versions are much more advanced. There was also a fourth networking option, known as VM/Pass-Through Facility (or more commonly called, PVM). PVM, like VTAM, allowed for connections to remote VM/CMS systems, as well as other IBM systems. If two VM/CMS nodes were linked together over a channel-to-channel link or bisync link (possibly using a dialup modem or leased line), a user could remotely connect to either system by entering "DIAL PVM" on the VM login screen, then entering the system node name (or choosing it from a list of available nodes). Alternatively, a user running CMS could use the PASSTHRU program that was installed alongside PVM, allowing for quick access to remote systems without having to log out of the user's session. PVM also supported accessing non-VM systems, by utilizing a 3x74 emulation technique. Later releases of PVM also featured a component that could accept connections from a SNA network. VM was also the cornerstone operating system of BITNET, as the RSCS system available for VM provided a simple network that was easy to implement, and somewhat reliable. VM sites were interlinked by means of an RSCS VM on each VM system communicating with one another, and users could send and receive messages, files, and batch jobs through RSCS. The "NOTE" command used XEDIT to display a dialog to create an email, from which the user could send it. If the user specified an address in the form of user at node, the email file would be delivered to RSCS, which would then deliver it to the target user on the target system. If the site has TCP/IP installed, RSCS could work with the SMTP service machine to deliver notes (emails) to remote systems, as well as receive them. If the user specified user at some.host.name, the NOTE program would deliver the email to the SMTP service machine, which would then route it out to the destination site on the Internet. VM's role changed within IBM when hardware evolution led to significant changes in processor architecture. Backward compatibility remained a cornerstone of the IBM mainframe family, which still uses the basic instruction set introduced with the original System/360; but the need for efficient use of the 64-bit zSeries made the VM approach much more attractive. VM was also utilized in data centers converting from DOS/VSE to MVS and is useful when running mainframe AIX and Linux, platforms that were to become increasingly important. The current z/VM platform has finally achieved the recognition within IBM that VM users long felt it deserved. Some z/VM sites run thousands of simultaneous virtual machine users on a single system. z/VM was first released in October 2000 and remains in active use and development. IBM and third parties have offered many applications and tools that run under VM. Examples include RAMIS, FOCUS, SPSS, NOMAD, DB2, REXX, RACF, and OfficeVision. Current VM offerings run the gamut of mainframe applications, including HTTP servers, database managers, analysis tools, engineering packages, and financial systems. CP commands As of release 6, the VM/370 Control Program has a number of commands for General Users, concerned with defining and controlling the user's virtual machine. Lower-case portions of the command are optional OpenEdition Extensions Starting with VM/ESA Version 2, IBM introduced the chargeable optional feature OpenEdition for VM/ESA Shell and Utilities Feature, which provides POSIX compatibility for CMS. The stand-out feature was a UNIX shell for CMS. The C compiler for this UNIX environment is provided by either C/370 or C for VM/ESA. Neither the CMS filesystem nor the standard VM Shared File System has any support for UNIX-style files and paths; instead, the Byte File System is used. Once a BFS extent is created in an SFS file pool, the user can mount it using the OPENVM MOUNT /../VMBFS:fileservername:filepoolname /path/to/mount/point. The user must also mount the root filesystem, done with OPENVM MOUNT /../VMBFS:VMSYS:ROOT/ /, a shell can then be started with OPENVM SHELL. Unlike the normal SFS, access to BFS filesystems is controlled by POSIX permissions (with chmod and chown). Starting with z/VM Version 3, IBM integrated OpenEdition into z/VM and renamed it OpenExtensions. VM mascot In the early 1980s, the VM group within SHARE (the IBM user group) sought a mascot or logo for the community to adopt. This was in part a response to IBM's MVS users selecting the turkey as a mascot (chosen, according to legend, by the MVS Performance Group in the early days of MVS, when its performance was a sore topic). In 1983, the teddy bear became VM's de facto mascot at SHARE 60, when teddy bear stickers were attached to the nametags of "cuddlier oldtimers" to flag them for newcomers as "friendly if approached". The bears were a hit and soon appeared widely. Bears were awarded to inductees of the "Order of the Knights of VM", individuals who made "useful contributions" to the community. Criticism While VM was relatively light-weight (when compared to its counterparts, such as MVS), VM was somewhat unstable in its early days. It was considered quite a feat to keep a VM/370 system up for more than a week. Users also criticized the CMS file system, noting that other operating systems in the mid-1980s had directories, symbolic links, and other key features; CMS had none of these until 1988 when VM/SP release 6 came out, which introduced the Shared File System and alleviated these issues. Some users also noted that VM OpenEdition was somewhat "unnecessary." Notes See also Time-sharing system evolution References External links VM sources Bob DuCharme, Operating Systems Handbook, Part 5: VM/CMS– a fairly detailed user's guide to VM/CMS E. C. Hendricks and T. C. Hartmann, "Evolution of a Virtual Machine Subsystem", IBM Systems Journal Vol. 18, pp. 111–142 (1979)– RSCS design and implementation IBM Corporation, IBM Virtual Machine Facility/370 Introduction, GC20-1800, (1972)– the original manual Other resources IBM Redbooks Publication – z/VM textbook IBM: z/VM portal IBM: z/VM manuals VM/PC documentation on bitsavers Time-sharing operating systems IBM mainframe operating systems Virtualization software Assembly language software IBM ESA/390 operating systems de:Z/VM it:VM/CMS

Operating System (OS)

Boot Camp (software) Boot Camp Assistant is a multi boot utility included with Apple Inc.'s macOS (previously ) that assists users in installing Microsoft Windows operating systems on Intel-based Macintosh computers. The utility guides users through non-destructive disk partitioning (including resizing of an existing HFS+ or APFS partition, if necessary) of their hard disk drive or solid state drive and installation of Windows device drivers for the Apple hardware. The utility also installs a Windows Control Panel applet for selecting the default boot operating system. Initially introduced as an unsupported beta for Mac OS X 10.4 Tiger, the utility was first introduced with Mac OS X 10.5 Leopard and has been included in subsequent versions of the operating system ever since. Previous versions of Boot Camp supported Windows XP and Windows Vista. Boot Camp 4.0 for Mac OS X 10.6 Snow Leopard version 10.6.6 up to Mac OS X 10.8 Mountain Lion version 10.8.2 only supported Windows 7. However, with the release of Boot Camp 5.0 for Mac OS X 10.8 Mountain Lion in version 10.8.3, only 64-bit versions of Windows 7 and Windows 8 are officially supported. Boot Camp 6.0 added support for 64-bit versions of Windows 10. Boot Camp 6.1, available on macOS 10.12 Sierra and later, will only accept new installations of Windows 7 and later; this requirement was upgraded to requiring Windows 10 for macOS 10.14 Mojave. Boot Camp is currently not available on Apple silicon Macs, however, Craig Federighi has stated that there is technically nothing stopping ARM-based versions of Windows 10 and Windows 11 from running on Apple silicon processors; Microsoft would just need to change the licensing policies regarding ARM-based Windows 10 and Windows 11, for currently only OEMs who pre-install Windows 10 and Windows 11 on their products may purchase licenses for it – it is not publicly available to consumers like other versions of Windows 10 and Windows 11. It is already possible to run ARM-based Windows 10 (only Windows Insider builds, as they are the only widely available ARM builds of Windows 10) through the QEMU emulator and Parallels Desktop virtualization software (also supporting Windows 11 and Linux), furthering Federighi's statement. It's currently rumored that Microsoft's exclusivity deal with Qualcomm will expire sometime in early 2022, which would allow Apple and other manufacturers to provide support for Windows on their ARM-based machines if it were not to be renewed.[citation needed] Overview Installation Setting up Windows 10 on a Mac requires an ISO image of Windows 10 provided by Microsoft. Boot Camp combines Windows 10 with install scripts to load hardware drivers for the targeted Mac computer. Boot Camp currently supports Windows 10 on a range of Macs dated mid-2012 or newer. Startup Disk By default, Mac will always boot from the last-used startup disk. Holding down the option key (⌥) at startup brings up the boot manager, which allows the user to choose which operating system to start the device in. When using a non-Apple keyboard, the alt key usually performs the same action. The boot manager can also be launched by holding down the "menu" button on the Apple Remote at startup. On older Macs, its functionality relies on BIOS emulation through EFI and a partition table information synchronization mechanism between GPT and MBR combined. On newer Macs, Boot Camp keeps the hard disk as a GPT so that Windows is installed and booted in UEFI mode. Requirements Mac OS X 10.7 Lion and OS X 10.8 Mountain Lion Apple's Boot Camp system requirements lists the following requirements for Mac OS X Lion and OS X Mountain Lion: 8 GB USB storage device, or external drive formatted as MS-DOS (FAT) for installation of Windows drivers for Mac hardware 20 GB free hard disk space for a first-time installation or 40 GB for an upgrade from a previous version of Windows A full version of one of the following operating systems: Windows 7 Home Premium, Professional, or Ultimate (64-bit editions only) Windows 8 and Windows 8 Professional (64-bit editions only) Windows 10 Home, Pro, Pro for Workstation, Education or Enterprise (64-bit editions only) Mac OS X 10.5 Leopard and Mac OS X 10.6 Snow Leopard Apple lists the following requirements for Mac OS X 10.5 Leopard and Mac OS X 10.6 Snow Leopard: An Intel-based Macintosh computer with the latest firmware (Early Intel-based Macintosh computers require an EFI firmware update for BIOS compatibility). A Mac OS X 10.5 Leopard or Mac OS X 10.6 Snow Leopard installation disc or Mac OS X Disc 1 included with Macs that have Mac OS X 10.5 Leopard or Mac OS X 10.6 Snow Leopard preinstalled; this disc is needed for installation of Windows drivers for Mac hardware 10 GB free hard disk space (16 GB is recommended for Windows 7) A full version of one of the following operating systems: Windows XP Home Edition or Windows XP Professional Edition with Service Pack 2 or higher (32-bit editions only) Windows Vista Home Basic, Home Premium, Business, Enterprise or Ultimate (32-bit and 64-bit editions) Windows 7 Home Premium, Professional, Enterprise or Ultimate (32-bit and 64-bit editions) Supported Macintosh computers with Windows 8 Officially, the earliest Macintosh models that support Windows 8 are the mid-2011 MacBook Air, 13-inch-mid-2011 or 15 and 17-inch-mid-2010 MacBook Pro, mid-2011 Mac Mini, 21-inch-mid-2011 or 27-inch-mid-2010 iMac, and early 2009 Mac Pro. By running the Boot Camp assistant with a compatible version of Microsoft Windows setup disc in the drive and switching to a Windows 8 disc when Mac OS X reboots the machine to begin installing Windows, Windows 8 can be installed on older unsupported hardware. This can also work with Windows 10. Limitations Boot Camp will only help the user partition their disk if they currently have only a primary HFS partition, an EFI System Partition, and a Mac OS X Recovery Partition. Thus, for example, it is not possible to maintain an additional storage partition. A workaround has been discovered that involves interrupting the standard procedure after creating the Boot Camp partition, resizing the primary Mac OS X partition and creating a third partition in the now available space, then continuing with the Windows install. Changes to the partition table after Windows is installed are officially unsupported, but can be achieved with the help of third-party software. Boot Camp does not help users install Linux, and does not provide drivers for it. Most methods for dual-booting with Linux on Mac rely on manual disk partitioning, and the use of an EFI boot manager such as rEFInd. Despite Macs transitioning to Thunderbolt 3 in 2016, Boot Camp does not currently support running Windows with a Thunderbolt 3-powered External GPU (eGPU) unit under macOS High Sierra, macOS Mojave or macOS Catalina. Apple has not publicly commented on why this limitation is in place. Boot Camp version history Boot Camp support software (for Windows) version history See also Parallels Desktop for Mac rEFIt and rEFInd VMware Fusion VirtualBox References External links Boot Camp support page and installation instructions Using the Apple Bluetooth Wireless Keyboard in Boot Camp Troubleshooting Internet Connectivity Issues on Boot Camp with Windows 8 2006 software Apple Inc. file systems Apple Inc. software Boot loaders

Operating System (OS)

Arduino Uno The Arduino Uno is an open-source microcontroller board based on the Microchip ATmega328P microcontroller and developed by Arduino.cc. The board is equipped with sets of digital and analog input/output (I/O) pins that may be interfaced to various expansion boards (shields) and other circuits. The board has 14 digital I/O pins (six capable of PWM output), 6 analog I/O pins, and is programmable with the Arduino IDE (Integrated Development Environment), via a type B USB cable. It can be powered by the USB cable or by an external 9-volt battery, though it accepts voltages between 7 and 20 volts. It is similar to the Arduino Nano and Leonardo. The hardware reference design is distributed under a Creative Commons Attribution Share-Alike 2.5 license and is available on the Arduino website. Layout and production files for some versions of the hardware are also available. The word "uno" means "one" in Italian and was chosen to mark the initial release of Arduino Software. The Uno board is the first in a series of USB-based Arduino boards; it and version 1.0 of the Arduino IDE were the reference versions of Arduino, which have now evolved to newer releases. The ATmega328 on the board comes preprogrammed with a bootloader that allows uploading new code to it without the use of an external hardware programmer. While the Uno communicates using the original STK500 protocol, it differs from all preceding boards in that it does not use the FTDI USB-to-serial driver chip. Instead, it uses the Atmega16U2 (Atmega8U2 up to version R2) programmed as a USB-to-serial converter. History The Arduino project started at the Interaction Design Institute Ivrea (IDII) in Ivrea, Italy. At that time, the students used a BASIC Stamp microcontroller, at a cost that was a considerable expense for many students. In 2003, Hernando Barragán created the development platform Wiring as a Master's thesis project at IDII, under the supervision of Massimo Banzi and Casey Reas, who are known for work on the Processing language. The project goal was to create simple, low-cost tools for creating digital projects by non-engineers. The Wiring platform consisted of a printed circuit board (PCB) with an ATmega168 microcontroller, an IDE based on Processing, and library functions to easily program the microcontroller. In 2003, Massimo Banzi, with David Mellis, another IDII student, and David Cuartielles, added support for the cheaper ATmega8 microcontroller to Wiring. But instead of continuing the work on Wiring, they forked the project and renamed it Arduino. Early arduino boards used the FTDI USB-to-serial driver chip and an ATmega168. The Uno differed from all preceding boards by featuring the ATmega328P microcontroller and an ATmega16U2 (Atmega8U2 up to version R2) programmed as a USB-to-serial converter. Technical specifications Microcontroller: Microchip ATmega328P Operating Voltage: 5 Volts Input Voltage: 7 to 20 Volts Digital I/O Pins: 14 (of which 6 can provide PWM output) PWM Pins: 6 (Pin # 3, 5, 6, 9, 10 and 11) UART: 1 I2C: 1 SPI: 1 Analog Input Pins: 6 DC Current per I/O Pin: 20 mA DC Current for 3.3V Pin: 50 mA Flash Memory: 32 KB of which 0.5 KB used by bootloader SRAM: 2 KB EEPROM: 1 KB Clock Speed: 16 MHz Length: 68.6 mm Width: 53.4 mm Weight: 25 g ICSP Header: Yes Power Sources: DC Power Jack & USB Port Headers General pin functions LED: There is a built-in LED driven by digital pin 13. When the pin is high value, the LED is on, when the pin is low, it is off. VIN: The input voltage to the Arduino/Genuino board when it is using an external power source (as opposed to 5 volts from the USB connection or other regulated power source). You can supply voltage through this pin, or, if supplying voltage via the power jack, access it through this pin. 5V: This pin outputs a regulated 5V from the regulator on the board. The board can be supplied with power either from the DC power jack (7 - 20V), the USB connector (5V), or the VIN pin of the board (7-20V). Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage the board. 3V3: A 3.3 volt supply generated by the on-board regulator. Maximum current draw is 50 mA. GND: Ground pins. IOREF: This pin on the Arduino/Genuino board provides the voltage reference with which the microcontroller operates. A properly configured shield can read the IOREF pin voltage and select the appropriate power source, or enable voltage translators on the outputs to work with the 5V or 3.3V. Reset: Typically used to add a reset button to shields that block the one on the board. Special pin functions Each of the 14 digital pins and 6 analog pins on the Uno can be used as an input or output, under software control (using pinMode(), digitalWrite(), and digitalRead() functions). They operate at 5 volts. Each pin can provide or receive 20 mA as the recommended operating condition and has an internal pull-up resistor (disconnected by default) of 20-50K ohm. A maximum of 40mA must not be exceeded on any I/O pin to avoid permanent damage to the microcontroller. The Uno has 6 analog inputs, labeled A0 through A5; each provides 10 bits of resolution (i.e. 1024 different values). By default, they measure from ground to 5 volts, though it is possible to change the upper end of the range using the AREF pin and the analogReference() function. In addition, some pins have specialized functions: Serial / UART: pins 0 (RX) and 1 (TX). Used to receive (RX) and transmit (TX) TTL serial data. These pins are connected to the corresponding pins of the ATmega8U2 USB-to-TTL serial chip. External interrupts: pins 2 and 3. These pins can be configured to trigger an interrupt on a low value, a rising or falling edge, or a change in value. PWM (pulse-width modulation): pins 3, 5, 6, 9, 10, and 11. Can provide 8-bit PWM output with the analogWrite() function. SPI (Serial Peripheral Interface): pins 10 (SS), 11 (MOSI), 12 (MISO), and 13 (SCK). These pins support SPI communication using the SPI library. TWI (two-wire interface) / I²C: pin SDA (A4) and pin SCL (A5). Support TWI communication using the Wire library. AREF (analog reference): Reference voltage for the analog inputs. Communication The Arduino/Genuino Uno has a number of facilities for communicating with a computer, another Arduino/Genuino board, or other microcontrollers. The ATmega328 provides UART TTL (5V) serial communication, which is available on digital pins 0 (RX) and 1 (TX). An ATmega16U2 on the board channels this serial communication over USB and appears as a virtual com port to software on the computer. The 16U2 firmware uses the standard USB COM drivers, and no external driver is needed. However, on Windows, a .inf file is required. Arduino Software (IDE) includes a serial monitor which allows simple textual data to be sent to and from the board. The RX and TX LEDs on the board will flash when data is being transmitted via the USB-to-serial chip and USB connection to the computer (but not for serial communication on pins 0 and 1). A SoftwareSerial library allows serial communication on any of the Uno's digital pins. Automatic (software) reset Rather than requiring a physical press of the reset button before an upload, the Arduino/Genuino Uno board is designed in a way that allows it to be reset by software running on a connected computer. One of the hardware flow control lines (DTR) of the ATmega8U2/16U2 is connected to the reset line of the ATmega328 via a 100 nanofarad capacitor. When this line is asserted (taken low), the reset line drops long enough to reset the chip. This setup has other implications. When the Uno is connected to a computer running Mac OS X or Linux, it resets each time a connection is made to it from software (via USB). For the following half-second or so, the bootloader is running on the Uno. While it is programmed to ignore malformed data (i.e. anything besides an upload of new code), it will intercept the first few bytes of data sent to the board after a connection is opened. See also AVR microcontrollers Atmel AVR instruction set In-system programming References Further reading External links Uno Rev3 Schematic Board comparisons: Differences Between Official Arduino Uno Board Revisions (R1/R2/R3) Comparison of Various Arduino Boards Arduino Software Cheat Sheet Pinout Diagrams Arduino Uno Board ATmega328 DIP ATmega328 SMD Mechanical Dimensions and Hole Patterns Dimensions, Hole Patterns, Header Locations and PCB Templates Arduino

Operating System (OS)

DSOS DSOS (Deep Six Operating System) was a real-time operating system (sometimes referred to as an operating system kernel) developed by Texas Instruments' Geophysical Services division (GSI) in the mid-1970s. Background The Geophysical Services division of Texas Instruments' main business was to search for oil. They would collect data in likely spots around the world, process that data using high performance computers, and produce analyses that guided oil companies toward promising sites for drilling. Much of the oil being sought was to be found beneath the ocean, hence GSI maintained a fleet of ships to collect seismic data from remote regions of the world. In order to do this properly it was essential that the ships be navigated precisely - if you find evidence of oil, you can't just mark an "X" on a tree - the oil is thousands of feet below the ocean and you are typically hundreds of miles from land. But this was a decade or more before GPS existed, thus the processing load to keep an accurate picture of "where you are" was considerable. The GEONAV systems, which used DSOS (Frailey, 1975) as their operating system, performed the required navigation and, in addition, collected, processed and stored the seismic data being received in real-time. Deep Six Operating System The name "Deep Six Operating System" was the brainchild of Phil Ward (subsequently a world-renowned GPS expert) who, at the time, was manager of the project and slightly skeptical of the computer science professor, Dennis Frailey, who insisted that an operating system was the solution to the problem at hand. In a sense the system lived up to its name, according to legend. Supposedly one of the ships hit an old World War II sea mine off the coast of Egypt and sank while being navigated by GEONAV and DSOS. Why an Operating System? In the 1970s, most real-time applications did not use operating systems because the latter were perceived as adding too much overhead. Typical computers of the time had barely enough computing power to handle the tasks at hand. Moreover, most software of this type was written in assembly language. As a consequence, real-time systems were classic examples of "spaghetti code" - complex masses of assembly language software using all sorts of machine-dependent tricks to achieve maximum performance. DSOS ran on a Texas Instruments 980 minicomputer being used for marine navigation on GSI's fleet. DSOS was created to bring some order to the chaos that was typical of real-time system design at that time. The 980 was, for its time, a relatively powerful small computer that offered memory protection and multiple-priority interrupt capabilities. DSOS was designed to exploit these features. Significance DSOS (Frailey, 1975) was one of the pioneering efforts in real-time operating systems. Incorporating many of the principles being introduced at the time in mainframe systems, such as semaphores, memory management, task management and software interrupts, it used a clever scheme to assure appropriate real-time performance while providing many services previously uncommon in the real-time domain (such as an orderly way to communicate with external devices and computer operators, multitasking, maintenance of records, a disciplined form of inter-task communication, a reliable real-time clock, memory protection, and debugging support). It remained in use for at least three decades and it demonstrated that, if well designed, an operating system can actually make a real-time system faster (and vastly more maintainable) than what had been typical before. Today, almost all real-time applications use operating systems of this type. References Frailey, Dennis J., "DSOS - A Skeletal, Real-Time, Minicomputer Operating System," Software - Practice and Experience, Vol. 5, no. 1 (January, 1975), 5-18. Real-time operating systems

Operating System (OS)

Installable File System The Installable File System (IFS) is a filesystem API in MS-DOS/PC DOS 4.x, IBM OS/2 and Microsoft Windows that enables the operating system to recognize and load drivers for file systems. History When IBM and Microsoft were co-developing OS/2, they realized that the FAT file system did not offer some of the features modern OSes would require, and Microsoft began developing the High Performance File System (HPFS), codenamed Pinball. Instead of coding it inside the kernel, as FAT was, Microsoft developed a "driver-based" filesystem API that could allow them and other developers to add new filesystems to the kernel without needing to modify it. When Microsoft stopped working on OS/2, IBM continued using the IFS interface and Microsoft implemented a similar one in Windows NT. Implementations IFS in DOS 4.x IFS in OS/2 The IFS provided a basic and powerful interface for programming filesystems. It was introduced in 1989 in OS/2 1.20, along with the HPFS filesystem. Filesystem drivers executed in kernel-space (ring 0) and are divided in four principal pieces: microIFS, miniIFS, IFS, helpers. Only the IFS and the filesystem code itself is required and it is loaded via an "IFS=" statement in the CONFIG.SYS file. It is a NE 16-bit dynamically loaded library. No matter if it is a 32-bit OS/2 (2.0 and newer), the IFS is always 16-bit (although extraofficially you can make a 32-bit IFS). The microIFS is a piece of code that loads in memory the kernel and the miniIFS and jumps to kernel execution. It is usually in the boot portion of the filesystem. The miniIFS is a piece of code that is called by the kernel to load the first IFS statement that appears in the CONFIG.SYS file, so the first IFS statement must be the boot's filesystem for the system to be able to boot. The helpers are 16-bit (for OS/2 1.x) or 32-bit (for OS/2 2.x and up), are executed in user-space (ring 3) and contain the code used for typical filesystem maintenance, and are called by CHKDSK and FORMAT utilities. This four-piece scheme allowed developers to dynamically add a new bootable filesystem, as the ext2 driver for OS/2 demonstrated. CD-ROM filesystem driver (ISO 9660) was added in OS/2 2.0, UDF was added in OS/2 4.0 and JFS was added in OS/2 4.5. ArcaOS, the latest packaging of OS/2, has a number of filesystem drivers available, including FAT32. There was also an official 32-bit HPFS IFS, called HPFS386 that improved performance and added some features, like variable size cache and Access Control Lists, and was available only in certain OS/2 server editions. The FAT filesystem was never removed from the kernel and officially never an IFS, although there are FAT IFS that added features like long file names (LFNs), FAT32 support, etc. Network file-sharing protocols like NFS and SMB are also implemented using IFS, and the IFS interface never changed. IFS in Windows 3.11 and 9x IFSHLP.SYS (the Installable File System Helper) is an MS-DOS device driver that was first released as part of Microsoft Windows 3.11. It enables native 32-bit file access in Windows 386 Enhanced Mode by bypassing the 16-bit DOS API and ensuring that no other real mode driver intercepts INT 21h calls. The protected mode counterpart of IFSHLP.SYS is IFSMGR.386 in Windows 3.11 and IFSMGR.VXD in Windows 95 and Windows 98. IFS in Windows NT The IFS API is part of the Windows Driver Kit. When Microsoft stopped developing OS/2 and concentrated on what was then called OS/2 NT, they took the IFS ideas with it, along with the HPFS filesystem. Instead of being a four-piece scheme, NT IFS was redesigned into a two-piece scheme. microIFS and miniIFS were removed from the scheme. IFS and helpers remain as the same, but later, in Windows NT 4.0, a defragmentation helper (DEFRAG) was added. Microsoft's original NTLDR was coded for loading the NT kernel from FAT, HPFS or NTFS, but subsequent versions dropped HPFS support. All of the drivers and helpers became 32-bit PE executables. The FAT file system was moved out of the Kernel to an IFS and was heavily optimized for performance, taking advantage of the 32-bit processing capabilities (being called FASTFAT). Original Windows NT 3.1 incorporated FAT, HPFS (Pinball) and the newly created NTFS drivers, along with a new and improved CD-ROM filesystem driver that incorporated long file names using the Microsoft Joliet filesystem. Windows NT 3.51 added per-file compression to NTFS and to the IFS interface. In Windows NT 4.0 HPFS was removed. In Windows 2000 FASTFAT was updated to support FAT32 and UDF was added. Windows 2000 modified the IFS interface to add per-file encryption. Network file-sharing protocols and antivirus are also implemented using IFS. Apple started including read only HFS+ drivers in Mac OS X 10.6's version of Boot Camp for use in Windows XP, Windows Vista, and Windows 7. Further reading See also Virtual file system List of file systems Comparison of file systems Network redirector Dokan Library References External links File systems driver design guide at Microsoft Docs ext2/ext3/ext4 Ext2Fsd is a GPL file system driver for Windows 2000 to Windows 8 (32Bit and 64Bit); it supports writing/multiple codepages, ext3 htree, journal since version 0.50 available ext2 IFS for Windows NT (Read only) Ext2IFS / Another ext2-3 IFS for Windows NT/2000/XP/2003 (Read/Write; support for UTF-8 file names and ext3 htree; ext3 journal not supported ) ReiserFS ReiserFS IFS for Windows NT (Read only) HFS Commercial HFS IFS for Windows NT OS/2 HFS IFS for OS/2 NTFS and FAT IFS for OS/2 FTP server offering IFS drivers for OS/2 Other CBFS Storage - cross-platform single-file virtual filesystem with encryption and compression CBFS Connect - SDK that lets developers create installable virtual file systems for Windows in user mode RomFS - Windows driver examples WinFUSE - a .NET based Filesystem in USErspace framework that uses SMB instead of IFS Dokany - an MIT-licensed framework for filesystems in Windows userspace that uses a separate kernel driver, with available .NET bindings Computer file systems IBM file systems OS/2 Microsoft application programming interfaces

Operating System (OS)

Linspire Linspire (formerly Lindows) is a commercial operating system based on Debian and Ubuntu and currently owned by PC/OpenSystems LLC. It had been owned by Linspire. Inc. from 2001 to 2008, and then by Xandros from 2008 to 2017. On July 1, 2008, Linspire stockholders elected to change the company's name to Digital Cornerstone, and all assets were acquired by Xandros. On August 8, 2008, Andreas Typaldos, CEO of Xandros, announced that Linspire would be discontinued in favor of Xandros; Freespire would change its base code from Ubuntu to Debian; and the Linspire brand would cease to exist. On January 1, 2018, it was announced that PC/OpenSystems LLC had purchased Linspire and Freespire from Xandros, and that Linspire 7 was available for $79.99, while Freespire 3 was available for free. History Based in San Diego, California, Lindows, Inc. was founded in August 2001 by Michael Robertson with the goal of developing a Linux-based operating system capable of running major Microsoft Windows applications. It based its Windows compatibility on the Wine API. The company later abandoned this approach in favor of attempting to make Linux applications easy to download, install and use. To this end a program named "CNR" was developed: based on Debian's Advanced Packaging Tool, it provides an easy-to-use graphical user interface and a slightly modified package system for an annual fee. The first public release of Lindows was version 1.0, released in late 2001. In 2002, Microsoft sued Lindows, Inc. claiming the name Lindows constituted an infringement of their Windows trademark. Microsoft's claims were rejected by the court, which asserted that Microsoft had used the term windows to describe graphical user interfaces before the Windows product was ever released, and that the windowing technique had already been implemented by Xerox and Apple Computer many years before. Microsoft sought a retrial and after this was postponed in February 2004, offered to settle the case. As part of the licensing settlement, Microsoft paid an estimated $20 million, and Lindows, Inc. transferred the Lindows trademark to Microsoft and changed its name to Linspire, Inc. On 15 June 2005, Michael Robertson stepped down as CEO of Linspire, Inc. He continues as chairman and was replaced as CEO by Kevin Carmony. Linspire became a member of the Interop Vendor Alliance which was founded in 2006. On February 8, 2007, Linspire, Inc. and Canonical Ltd, the lead sponsor and developer of the Ubuntu operating system, announced plans for a new technology partnership, with Linspire aiming to "begin basing ... [their] desktop Linux offerings on Ubuntu." On 13 June 2007, Linspire and Microsoft announced an interoperability collaboration agreement with a focus on document format compatibility, instant messaging, digital media, web search, and patent covenants for Linspire customers. This agreement has been criticised, most notably by the Groklaw website for being disingenuously short-lived and limited, and against the spirit of the GNU General Public License. Kevin Carmony, in one of the regular "Linspire Letters," asserted that the agreement would "bring even more choices to desktop Linux users [and] ... offer a "better" Linux experience." Linspire bases its product code names on fish found near its headquarters: Linspire/LindowsOS 4.5 was code named Coho; Linspire Five-0 (5.0 and 5.1) and Freespire 1.0, Marlin; and Freespire 2.0 and Linspire 6.0, Skipjack. CNR Linspire's CNR (originally Click'N'Run) was a software distribution service based on Debian's APT. It was designed to serve as a GUI-based, user-accessible means of downloading and installing various applications, both free and proprietary. The service allowed users to install available applications using a single click. CNR also included a set of Click and Buy (CNB) software, which included many commercial applications to members at a discounted rate. CNR had over 38,000 different software packages, ranging from simple applications to major commercial works such as Win4Lin and StarOffice. CNR was originally subscription-based with two tiers: basic service cost $20 annually, and gold, featuring discounts on some commercial applications, $50. In 2006, Linspire announced that the basic service was to be made available for free. Linspire planned to port CNR to the Ubuntu distribution. The company announced on April 24, 2006 that CNR would be released under an open source license. The release of the free CNR client was planned to coincide with the release of Freespire 2.0 and Linspire 6.0. On January 23, 2007, Linspire announced that it intended to provide CNR for other Linux distributions, both APT- and RPM-based, including Debian, Fedora, OpenSUSE and Ubuntu. This support was expected to appear in mid-2007. On February 8, 2007, Linspire, Inc. announced a partnership with Canonical Ltd., publisher of the Ubuntu Linux distribution. This deal would see Linspire and Freespire migrate from the unpredictable Debian release process to the semiannual Ubuntu release cycle. It was intended that the main Ubuntu distribution would become the first recipient of the opening of the Click'N'Run service to Linux distributions besides Linspire. Freespire In August 2005, Andrew Betts released Freespire, a Live CD based on Linspire. Some users mistook this for a product from Linspire, Inc. Linspire, Inc. offered users a "free Linspire" (purchase price discounted to $0) by using the coupon code "Freespire" until September 9, 2005. On April 24, 2006, Linspire announced its own project named "Freespire". This followed the model of community-oriented releases by Red Hat and Novell in the form of Fedora and openSUSE. Freespire was a community-driven and -supported project tied to the commercial Linspire distribution, and included previously proprietary elements from Linspire, such as the CNR Client, while other elements, which Linspire, Inc. licenses but does not own, like the Windows Media Audio compatibility libraries, remain closed-source. Consequently, there are two versions of Freespire, one with the closed source libraries, and one, called Freespire OSS Edition, that includes only open-source components. Freespire 1.0 was released on August 7, 2006, three weeks ahead of schedule. It is now known that Freespire will change its code base from Ubuntu to Debian on any future releases. On July 10, 2007 Linspire released Linspire 6.0, based on Freespire 2.0. The final release of Freespire was 2.0.8, released on 30 November 2007. This was based on Ubuntu 7.04 which was supported for 18 months and reached end-of-life on 19 October 2008. Freespire therefore receives no security updates from upstream at present. The distribution is now considered "Discontinued" by DistroWatch. Contributions Linspire, Inc. sponsored open source projects including the Pidgin and Kopete instant messaging clients, the Mozilla Firefox web browser, the ReiserFS file system, the Nvu WYSIWYG website editor, and the KDE-Apps.org and KDE-Look.org websites. In the past, Linspire has hosted several Linux and open source events, such as the annual Desktop Linux Summit, DebConf and the KDE Developers Conference. Criticism Linspire has drawn some criticism from the free software community. This has included criticism for including proprietary software, with GNU founder Richard Stallman commenting: "No other GNU/Linux distribution has backslided so far away from freedom. Switching from MS Windows to Linspire does not bring you to freedom, it just gets you a different master." In addition, following the initial Freespire announcement Pamela Jones of the Groklaw website published an article entitled "Freespire: A Linux Distro For When You Couldn't Care Less About Freedom;" that was highly critical of Linspire, Inc., and the Freespire project, for including closed-source components and advertising them as a favourable point—an action she classed as ignoring free and open-source software (FOSS) community values in a "community-driven" distribution, asserting that "Free Software isn't about proprietary drivers" and that "proprietary codecs, drivers and applications are not Open Source or open in any way." In response, Linspire, Inc. CEO Kevin Carmony stated via a journalist on the Linspire website that in ten years of holding out, the FOSS community has made relatively few gains, that many users are already using proprietary software and, although some would hold out, most would prefer to have something that works rather than nothing. He also asserted that the company believed in open source software, but also in the freedom of individuals to choose whatever software they want. See also Commercial use of copyleft works References External links Official website LugRadio podcast featuring an interview with Kevin Carmony Lindows reggae song included with Lindows OS Debian-based distributions Proprietary software Ubuntu derivatives Linux distributions

Operating System (OS)

IBM AIX AIX (Advanced Interactive eXecutive, pronounced , “ay-eye-ex”) is a series of proprietary Unix operating systems developed and sold by IBM for several of its computer platforms. Originally released for the IBM RT PC RISC workstation in 1986, AIX has supported a wide variety of hardware platforms, including the IBM RS/6000 series and later Power and PowerPC-based systems, IBM System i, System/370 mainframes, PS/2 personal computers, and the Apple Network Server. It is currently supported on IBM Power Systems alongside IBM i and Linux. AIX is based on UNIX System V with 4.3BSD-compatible extensions. It is certified to the UNIX 03 and UNIX V7 marks of the Single UNIX Specification, beginning with AIX versions 5.3 and 7.2 TL5 respectively. Older versions were previously certified to the UNIX 95 and UNIX 98 marks. AIX was the first operating system to have a journaling file system, and IBM has continuously enhanced the software with features such as processor, disk and network virtualization, dynamic hardware resource allocation (including fractional processor units), and reliability engineering ported from its mainframe designs. History Unix started life at AT&T's Bell Labs research center in the early 1970s, running on DEC minicomputers. By 1976, the operating system was in use at various academic institutions, including Princeton, where Tom Lyon and others ported it to the S/370, to run as a guest OS under VM/370. This port would later grow out to become UTS, a mainframe Unix offering by IBM's competitor Amdahl Corporation. IBM's own involvement in Unix can be dated to 1979, when it assisted Bell Labs in doing its own Unix port to the 370 (to be used as a build host for the 5ESS switch's software). In the process, IBM made modifications to the TSS/370 hypervisor to better support Unix. It took until 1985 for IBM to offer its own Unix on the S/370 platform, IX/370, which was developed by Interactive Systems Corporation and intended by IBM to compete with Amdahl UTS. The operating system offered special facilities for interoperating with PC/IX, Interactive/IBM's version of Unix for IBM PC compatible hardware, and was licensed at $10,000 per sixteen concurrent users. AIX Version 1, introduced in 1986 for the IBM RT PC workstation, was based on UNIX System V Releases 1 and 2. In developing AIX, IBM and Interactive Systems Corporation (whom IBM contracted) also incorporated source code from 4.2 and 4.3 BSD UNIX. Among other variants, IBM later produced AIX Version 3 (also known as AIX/6000), based on System V Release 3, for their POWER-based RS/6000 platform. Since 1990, AIX has served as the primary operating system for the RS/6000 series (later renamed IBM eServer pSeries, then IBM System p, and now IBM Power Systems). AIX Version 4, introduced in 1994, added symmetric multiprocessing with the introduction of the first RS/6000 SMP servers and continued to evolve through the 1990s, culminating with AIX 4.3.3 in 1999. Version 4.1, in a slightly modified form, was also the standard operating system for the Apple Network Server systems sold by Apple Computer to complement the Macintosh line. In the late 1990s, under Project Monterey, IBM and the Santa Cruz Operation planned to integrate AIX and UnixWare into a single 32-bit/64-bit multiplatform UNIX with particular emphasis on running on Intel IA-64 (Itanium) architecture CPUs. A beta test version of AIX 5L for IA-64 systems was released, but according to documents released in the SCO v. IBM lawsuit, less than forty licenses for the finished Monterey Unix were ever sold before the project was terminated in 2002. In 2003, the SCO Group alleged that (among other infractions) IBM had misappropriated licensed source code from UNIX System V Release 4 for incorporation into AIX; SCO subsequently withdrew IBM's license to develop and distribute AIX. IBM maintains that their license was irrevocable, and continued to sell and support the product until the litigation was adjudicated. AIX was a component of the 2003 SCO v. IBM lawsuit, in which the SCO Group filed a lawsuit against IBM, alleging IBM contributed SCO's intellectual property to the Linux codebase. The SCO Group, who argued they were the rightful owners of the copyrights covering the Unix operating system, attempted to revoke IBM's license to sell or distribute the AIX operating system. In March 2010, a jury returned a verdict finding that Novell, not the SCO Group, owns the rights to Unix. AIX 6 was announced in May 2007, and it ran as an open beta from June 2007 until the general availability (GA) of AIX 6.1 on November 9, 2007. Major new features in AIX 6.1 included full role-based access control, workload partitions (which enable application mobility), enhanced security (Addition of AES encryption type for NFS v3 and v4), and Live Partition Mobility on the POWER6 hardware. AIX 7.1 was announced in April 2010, and an open beta ran until general availability of AIX 7.1 in September 2010. Several new features, including better scalability, enhanced clustering and management capabilities were added. AIX 7.1 includes a new built-in clustering capability called Cluster Aware AIX. AIX is able to organize multiple LPARs through the multipath communications channel to neighboring CPUs, enabling very high-speed communication between processors. This enables multi-terabyte memory address range and page table access to support global petabyte shared memory space for AIX POWER7 clusters so that software developers can program a cluster as if it were a single system, without using message passing (i.e. semaphore-controlled Inter-process Communication). AIX administrators can use this new capability to cluster a pool of AIX nodes. By default, AIX V7.1 pins kernel memory and includes support to allow applications to pin their kernel stack. Pinning kernel memory and the kernel stack for applications with real-time requirements can provide performance improvements by ensuring that the kernel memory and kernel stack for an application is not paged out. AIX 7.2 was announced in October 2015, and released in December 2015. The principal feature of AIX 7.2 is the Live Kernel Update capability, which allows OS fixes to replace the entire AIX kernel with no impact to applications, by live migrating workloads to a temporary surrogate AIX OS partition while the original OS partition is patched. AIX 7.2 was also restructured to remove obsolete components. The networking component, bos.net.tcp.client was repackaged to allow additional installation flexibility. Unlike AIX 7.1, AIX 7.2 is only supported on systems based on POWER7 or later processors. Supported hardware platforms IBM RT PC The original AIX (sometimes called AIX/RT) was developed for the IBM RT PC workstation by IBM in conjunction with Interactive Systems Corporation, who had previously ported UNIX System III to the IBM PC for IBM as PC/IX. According to its developers, the AIX source (for this initial version) consisted of one million lines of code. Installation media consisted of eight 1.2M floppy disks. The RT was based on the IBM ROMP microprocessor, the first commercial RISC chip. This was based on a design pioneered at IBM Research (the IBM 801) . One of the novel aspects of the RT design was the use of a microkernel, called Virtual Resource Manager (VRM). The keyboard, mouse, display, disk drives and network were all controlled by a microkernel. One could "hotkey" from one operating system to the next using the Alt-Tab key combination. Each OS in turn would get possession of the keyboard, mouse and display. Besides AIX v2, the PICK OS also included this microkernel. Much of the AIX v2 kernel was written in the PL/8 programming language, which proved troublesome during the migration to AIX v3. AIX v2 included full TCP/IP networking, as well as SNA and two networking file systems: NFS, licensed from Sun Microsystems, and Distributed Services (DS). DS had the distinction of being built on top of SNA, and thereby being fully compatible with DS on and on midrange systems running OS/400 through IBM i. For the graphical user interfaces, AIX v2 came with the X10R3 and later the X10R4 and X11 versions of the X Window System from MIT, together with the Athena widget set. Compilers for Fortran and C were available. IBM PS/2 series AIX PS/2 (also known as AIX/386) was developed by Locus Computing Corporation under contract to IBM. AIX PS/2, first released in October 1988, ran on IBM PS/2 personal computers with Intel 386 and compatible processors. The product was announced in September 1988 with a baseline tag price of $595, although some utilities like uucp were included in a separate Extension package priced at $250. nroff and troff for AIX were also sold separately in a Text Formatting System package priced at $200. The TCP/IP stack for AIX PS/2 retailed for another $300. The X Window package was priced at $195, and featured a graphical environment called the AIXwindows Desktop, based on IXI's X.desktop. The C and FORTRAN compilers each had a price tag of $275. Locus also made available their DOS Merge virtual machine environment for AIX, which could run MS DOS 3.3 applications inside AIX; DOS Merge was sold separately for another $250. IBM also offered a $150 AIX PS/2 DOS Server Program, which provided file server and print server services for client computers running PC DOS 3.3. The last version of PS/2 AIX is 1.3. It was released in 1992 and announced to add support for non-IBM (non-microchannel) computers as well. Support for PS/2 AIX ended in March 1995. IBM mainframes In 1988, IBM announced AIX/370, also developed by Locus Computing. AIX/370 was IBM's fourth attempt to offer Unix-like functionality for their mainframe line, specifically the System/370 (the prior versions were a TSS/370-based Unix system developed jointly with AT&T c.1980, a VM/370-based system named VM/IX developed jointly with Interactive Systems Corporation c.1984, and a VM/370-based version of TSS/370 named IX/370 which was upgraded to be compatible with Unix System V). AIX/370 was released in 1990 with functional equivalence to System V Release 2 and 4.3BSD as well as IBM enhancements. With the introduction of the ESA/390 architecture, AIX/370 was replaced by AIX/ESA in 1991, which was based on OSF/1, and also ran on the System/390 platform. This development effort was made partly to allow IBM to compete with Amdahl UTS. Unlike AIX/370, AIX/ESA ran both natively as the host operating system, and as a guest under VM. AIX/ESA, while technically advanced, had little commercial success, partially because UNIX functionality was added as an option to the existing mainframe operating system, MVS, as MVS/ESA SP Version 4 Release 3 OpenEdition in 1994, and continued as an integral part of MVS/ESA SP Version 5, OS/390 and z/OS, with the name eventually changing from OpenEdition to Unix System Services. IBM also provided OpenEdition in VM/ESA Version 2 through z/VM. IA-64 systems As part of Project Monterey, IBM released a beta test version of AIX 5L for the IA-64 (Itanium) architecture in 2001, but this never became an official product due to lack of interest. Apple Network Servers The Apple Network Server (ANS) systems were PowerPC-based systems designed by Apple Computer to have numerous high-end features that standard Apple hardware did not have, including swappable hard drives, redundant power supplies, and external monitoring capability. These systems were more or less based on the Power Macintosh hardware available at the time but were designed to use AIX (versions 4.1.4 or 4.1.5) as their native operating system in a specialized version specific to the ANS called AIX for Apple Network Servers. AIX was only compatible with the Network Servers and was not ported to standard Power Macintosh hardware. It should not be confused with A/UX, Apple's earlier version of Unix for 68k-based Macintoshes. POWER ISA/PowerPC/Power ISA-based systems The release of AIX version 3 (sometimes called AIX/6000) coincided with the announcement of the first POWER1-based IBM RS/6000 models in 1990. AIX v3 innovated in several ways on the software side. It was the first operating system to introduce the idea of a journaling file system, JFS, which allowed for fast boot times by avoiding the need to ensure the consistency of the file systems on disks (see fsck) on every reboot. Another innovation was shared libraries which avoid the need for static linking from an application to the libraries it used. The resulting smaller binaries used less of the hardware RAM to run, and used less disk space to install. Besides improving performance, it was a boon to developers: executable binaries could be in the tens of kilobytes instead of a megabyte for an executable statically linked to the C library. AIX v3 also scrapped the microkernel of AIX v2, a contentious move that resulted in v3 containing no PL/8 code and being somewhat more "pure" than v2. Other notable subsystems included: IRIS GL, a 3D rendering library, the progenitor of OpenGL. IRIS GL was licensed by IBM from SGI in 1987, then still a fairly small company, which had sold only a few thousand machines at the time. SGI also provided the low-end graphics card for the RS/6000, capable of drawing 20,000 gouraud-shaded triangles per second. The high-end graphics card was designed by IBM, a follow-on to the mainframe-attached IBM 5080, capable of rendering 990,000 vectors per second. PHIGS, another 3D rendering API, popular in automotive CAD/CAM circles, and at the core of CATIA. Full implementation of version 11 of the X Window System, together with Motif as the recommended widget collection and window manager. Network file systems: NFS from Sun; AFS, the Andrew File System; and DFS, the Distributed File System. NCS, the Network Computing System, licensed from Apollo Computer (later acquired by HP). DPS on-screen display system. This was notable as a "plan B" in case the X11+Motif combination failed in the marketplace. However, it was highly proprietary, supported only by Sun, NeXT, and IBM. This cemented its failure in the marketplace in the face of the open systems challenge of X11+Motif and its lack of 3D capability. , AIX runs on IBM Power, System p, System i, System p5, System i5, eServer p5, eServer pSeries and eServer i5 server product lines, as well as IBM BladeCenter blades and IBM PureFlex compute nodes. In addition, AIX applications can run in the PASE subsystem under IBM i. POWER7 AIX features AIX 7.1 fully exploits systems based on POWER7 processors include the Active Memory Expansion (AME) feature, which increases system flexibility where system administrators can configure logical partitions (LPARs) to use less physical memory. For example, an LPAR running AIX appears to the OS applications to be configured with 80 GB of physical memory but the hardware actually only consumes 60 GB of physical memory. Active Memory Expansion is a virtual memory compression system which employs memory compression technology to transparently compress in-memory data, allowing more data to be placed into memory and thus expanding the memory capacity of POWER7 systems. Using Active Memory Expansion can improve system use and increase a system's throughput. AIX 7 automatically manages the size of memory pages used to automatically use 4 KB, 64 KB or a combination of those page sizes. This self-tuning feature results in optimized performance without administrative effort. POWER8 AIX features AIX 7.2 exploits POWER8 hardware features including accelerators and eight-way hardware multithreading. POWER9 AIX features AIX 7.2 exploits POWER9 secure boot technology. Versions Version history POWER/PowerPC releases AIX V7.3, December 10, 2021 AIX V7.2, October 5, 2015 Live update for Interim Fixes, Service Packs and Technology Levels replaces the entire AIX kernel without impacting applications Flash based filesystem caching Cluster Aware AIX automation with repository replacement mechanism SRIOV-backed VNIC, or dedicated VNIC virtualized network adapter support RDSv3 over RoCE adds support of the Oracle RDSv3 protocol over the Mellanox Connect RoCE adapters Requires POWER7 or newer CPUs AIX V7.1, September 10, 2010 Support for 256 cores / 1024 threads in a single LPAR The ability to run AIX V5.2 or V5.3 inside of a Workload Partition An XML profile based system configuration management utility Support for export of Fibre Channel adapters to WPARs VIOS disk support in a WPAR Cluster Aware AIX AIX Event infrastructure Role-based access control (RBAC) with domain support for multi-tenant environments AIX V6.1, November 9, 2007 Workload Partitions (WPARs) operating system-level virtualization Live Application Mobility Live Partition Mobility Security Role Based Access Control RBAC AIX Security Expert a system and network security hardening tool Encrypting JFS2 filesystem Trusted AIX Trusted Execution Integrated Electronic Service Agent for auto error reporting Concurrent Kernel Maintenance Kernel exploitation of POWER6 storage keys ProbeVue dynamic tracing Systems Director Console for AIX Integrated filesystem snapshot Requires POWER4 or newer CPUs AIX 6 withdrawn from Marketing effective April 2016 and from Support effective April 2017 AIX 5L 5.3, August 13, 2004, end of support April 30, 2012 NFS Version 4 Advanced Accounting Virtual SCSI Virtual Ethernet Exploitation of Simultaneous multithreading (SMT) Micro-Partitioning enablement POWER5 exploitation JFS2 quotas Ability to shrink a JFS2 filesystem Kernel scheduler has been enhanced to dynamically increase and decrease the use of virtual processors. AIX 5L 5.2, October 18, 2002, end of support April 30, 2009 Ability to run on the IBM BladeCenter JS20 with the PowerPC 970 Minimum level required for POWER5 hardware MPIO for Fibre Channel disks iSCSI Initiator software Participation in Dynamic LPAR Concurrent I/O (CIO) feature introduced for JFS2 released in Maintenance Level 01 in May 2003 AIX 5L 5.1, May 4, 2001, end of support April 1, 2006 Ability to run on an IA-64 architecture processor, although this never went beyond beta. Minimum level required for POWER4 hardware and the last release that worked on the Micro Channel architecture 64-bit kernel, installed but not activated by default JFS2 Ability to run in a Logical Partition on POWER4 The L stands for Linux affinity Trusted Computing Base (TCB) Support for mirroring with striping AIX 4.3.3, September 17, 1999 Online backup function Workload Manager (WLM) Introduction of topas utility AIX 4.3.2, October 23, 1998 AIX 4.3.1, April 24, 1998 First TCSEC security evaluation, completed December 18, 1998 AIX 4.3, October 31, 1997 Ability to run on 64-bit architecture CPUs IPv6 Web-based System Manager AIX 4.2.1, April 25, 1997 NFS Version 3 Y2K-compliant AIX 4.2, May 17, 1996 AIX 4.1.5, November 8, 1996 AIX 4.1.4, October 20, 1995 AIX 4.1.3, July 7, 1995 CDE 1.0 became the default GUI environment, replacing the AIXwindows Desktop. AIX 4.1.1, October 28, 1994 AIX 4.1, August 12, 1994 AIX Ultimedia Services introduced (multimedia drivers and applications) AIX 4.0, 1994 Run on RS/6000 systems with PowerPC processors and PCI busses. AIX 3.2 1992 AIX 3.1, (General Availability) February 1990 Journaled File System (JFS) filesystem type AIXwindows Desktop (based on X.desktop from IXI Limited) AIX 3.0 1989 (Early Access) LVM (Logical Volume Manager) was incorporated into OSF/1, and in 1995 for HP-UX, and the Linux LVM implementation is similar to the HP-UX LVM implementation. SMIT was introduced. IBM System/370 releases AIX/370 Version 1 Release 1 Announced March 15, 1988 Available February 16, 1989 AIX/370 Version 1 Release 2.1 Announced February 5, 1991 Available February February 22, 1991 Withdrawn December 31, 1992 AIX/ESA Version 2 Release 1 Announced March 31, 1992 Available June 26, 1992 Withdrawn Jun 19, 1993 AIX/ESA Version 2 Release 2 Announced December 15, 1992 Available February 26, 1993 Withdrawn Jun 19, 1993 IBM PS/2 releases AIX PS/2 v1.3, October 1992 Withdrawn from sale in US, March 1995 Patches supporting IBM ThinkPad 750C family of notebook computers, 1994 Patches supporting non PS/2 hardware and systems, 1993 AIX PS/2 v1.2.1, May 1991 AIX PS/2 v1.2, March 1990 AIX PS/2 v1.1, March 1989 AIX PS/2 (1–16 User Option) $795 AIX PS/2 (1–2 User Option) 595 AIX PS/2 Extensions 275 AIX PS/2 DOS Merge 275 AIX PS/2 Usability Services 275 AIX PS/2 Text Formatting System 220 AIX PS/2 X-Windows 214 AIX PS/2 VS FORTRAN 302 AIX PS/2 VS Pascal 302 AIX PS/2 C Language 302 AIX PS/2 Application Development Toolkit 192 AIX PS/2 Workstation Host Interface Program 441 AIX PS/2 Transmission Control Protocol/Internet Protocol (TCP/IP) 330 AIX PS/2 INmail (1)/INed (2)/INnet (1)/FTP 275 AIX Access for DOS Users 164 X-Windows for IBM DOS 214 IBM RT releases AIX RT v2.2.1, March 1991 AIX RT v2.2, March 1990 AIX RT v2.1, March 1989 X-Windows included on installation media AIX RT v1.1, 1986 User interfaces The default shell was Bourne shell up to AIX version 3, but was changed to KornShell (ksh88) in version 4 for XPG4 and POSIX compliance. Graphical The Common Desktop Environment (CDE) is AIX's default graphical user interface. As part of Linux Affinity and the free AIX Toolbox for Linux Applications (ATLA), open-source KDE Plasma Workspaces and GNOME desktop are also available. System Management Interface Tool SMIT is the System Management Interface Tool for AIX. It allows a user to navigate a menu hierarchy of commands, rather than using the command line. Invocation is typically achieved with the command smit. Experienced system administrators make use of the F6 function key which generates the command line that SMIT will invoke to complete it. SMIT also generates a log of commands that are performed in the smit.script file. The smit.script file automatically records the commands with the command flags and parameters used. The smit.script file can be used as an executable shell script to rerun system configuration tasks. SMIT also creates the smit.log file, which contains additional detailed information that can be used by programmers in extending the SMIT system. smit and smitty refer to the same program, though smitty invokes the text-based version, while smit will invoke an X Window System based interface if possible; however, if smit determines that X Window System capabilities are not present, it will present the text-based version instead of failing. Determination of X Window System capabilities is typically performed by checking for the existence of the DISPLAY variable. Database Object Data Manager (ODM) is a database of system information integrated into AIX, analogous to the registry in Microsoft Windows. A good understanding of the ODM is essential for managing AIX systems. Data managed in ODM is stored and maintained as objects with associated attributes. Interaction with ODM is possible via application programming interface (API) library for programs, and command-line utilities such us odmshow, odmget, odmadd, odmchange and odmdelete for shell scripts and users. SMIT and its associated AIX commands can also be used to query and modify information in the ODM. Example of information stored in the ODM database are: Network configuration Logical volume management configuration Installed software information Information for logical devices or software drivers List of all AIX supported devices Physical hardware devices installed and their configuration Menus, screens and commands that SMIT uses See also AOS, IBM's educational-market port of 4.3BSD IBM PowerHA SystemMirror (formerly HACMP) List of Unix systems nmon Operating systems timeline Service Update Management Assistant Vital Product Data (VPD) References External links IBM AIX IBM operating systems Power ISA operating systems PowerPC operating systems IBM Aix Object-oriented database management systems 1986 software

Operating System (OS)

Kylin (operating system) Kylin () is an operating system developed by academics at the National University of Defense Technology in the People's Republic of China since 2001. It is named after the mythical beast qilin. The first versions were based on FreeBSD and were intended for use by the Chinese military and other government organizations. With version 3.0 Kylin became Linux-based, and there is a version called NeoKylin which was announced in 2010. By 2019 NeoKylin variant is compatible with more than 4,000 software and hardware products and it ships pre-installed on most computers sold in China. Together, Kylin and Neokylin have 90% market share of the government sector. A separate project using Ubuntu as the base Linux operating system was announced in 2013. The first version of Ubuntu Kylin was released in April 2013. In August 2020, v10 of Kylin OS was launched. It is compatible with 10,000 hardware and software products and it "supports Google's Android ecosystem". FreeBSD version Development of Kylin began in 2001, when the National University of Defense Technology was assigned the mission of developing an operating system under the 863 Program intended to make China independent of foreign technology. The aim was "to support several kinds of server platforms, to achieve high performance, high availability and high security, as well as conforming to international standards of Unix and Linux operating systems". It was created using a hierarchy model, including "the basic kernel layer which is similar to Mach, the system service layer which is similar to BSD and the desktop environment which is similar to Windows". It was designed to comply with the UNIX standards and to be compatible with Linux applications. In February 2006, "China Military Online" (a website sponsored by PLA Daily of the Chinese People's Liberation Army) reported the "successful development of the Kylin server operating system", which it said was "the first 64-bit operating system with high security level (B2 class)" and "also the first operating system without Linux kernel that has obtained Linux global standard authentification by the international Free Standards Group". In April 2006, it was said that the Kylin operating system was largely based on FreeBSD 5.3. An anonymous Chinese student in Australia, who used the pseudonym "Dancefire", carried out a kernel similarity analysis and showed that the similarities between the two operating systems reached 99.45 percent. One of Kylin's developers confirmed that Kylin was based on FreeBSD during a speech at the international conference EuroBSDCon 2006. In 2009, a report presented to the US-China Economic and Security Review Commission stated that the purpose of Kylin is to make Chinese computers impenetrable to competing countries in the cyberwarfare arena. The Washington Post reported that: China has developed more secure operating software for its tens of millions of computers and is already installing it on government and military systems, hoping to make Beijing’s networks impenetrable to U.S. military and intelligence agencies. The deployment of Kylin was said to have "hardened key Chinese servers". Kylin Linux (NeoKylin) With the advent of version 3.0, Kylin has used the Linux kernel. In December 2010, it was announced that China Standard Software and the National University of Defense Technology had signed a strategic partnership to launch a version called NeoKylin. China Standard Software is the maker of the "NeoShine Linux" desktop series. NeoKylin is intended for use by government offices, national defense, energy and other sectors of the Chinese economy. In 2014, Bloomberg News reported that the northeastern city of Siping had migrated its computers from Microsoft Windows to NeoKylin, as part of a government effort to shift computer technology to Chinese suppliers. In September 2015 US computer maker Dell reported that 42% of personal computers they sold in China were now running NeoKylin. The operating system of the Tianhe-1 supercomputer is 64-bit Kylin Linux, which is oriented to high-performance parallel computing optimization, and supports power management and high-performance virtual computing. The newer Tianhe-2 also uses Kylin Linux. Ubuntu Kylin In 2013, Canonical reached an agreement with the Ministry of Industry and Information Technology of the People's Republic of China to release an Ubuntu-based Linux OS with features targeted at the Chinese market. Ubuntu Kylin has been described as "a loose continuation of China's Kylin OS". It is intended for desktop and laptop computers. The first official release, Ubuntu Kylin 13.04, was on 25 April 2013. See also Unity Operating System Canaima (operating system) – a similar project by the Venezuelan computer manufacturer VIT, C.A. and Chinese information technology company Inspur GendBuntu – a similar project used by Gendarmerie in France LiMux – a similar project of the city council of Munich Nova (operating system) – a similar project by the Cuban government Red Star OS – a similar project by the North Korean government References External links Kylin Official Website (Chinese) What is Kylin, Project Mission Statement, September 2004, at the Internet Archive (English) Official Kylin website, April 2006, on the Internet Archive (Chinese) NeoKylin (Chinese) NeoKylin Operating System at China Aid Software Service Center (English) Chinese-language Linux distributions Computing platforms FreeBSD Supercomputing in China Unix variants State-sponsored Linux distributions Linux distributions

Operating System (OS)

ANDOS ANDOS is a Russian operating system for Electronika BK series computers: BK-0010, BK-0011, and BK-0011M. They were based on the PDP-11 architecture by Digital Equipment Corporation. ANDOS was created in 1990 and released first in 1992. Initially it was developed by Alexey Nadezhin (by whose name the system is named) and later also by Sergey Kamnev, who joined the project. It was the only widespread system on BK series computers that used MS-DOS-compatible file system format. ANDOS used the FAT12 file system on 800 Kb floppy disks. For Electronika BK-0011M and BK-0011, ANDOS could emulate a BK-0010 by loading a BK-0010 read-only memory (ROM) image into BK-0011(M) random-access memory (RAM). In minimal configuration, the system could occupy less than 4 Kb of RAM. The system was able to support up to 64 disk drives (or hard disk drive partitions), and RAM disks in the computer's memory and tape recording. It could also have read-only access to MicroDOS file system format disks, although in the last version, this function was transferred from system core to the file manager and became optional. References Elektronika BK operating systems Assembly language software

Operating System (OS)

Windows on Windows In computing, Windows on Windows (commonly referred to as WOW,) is a compatibility layer of 32-bit versions of the Microsoft Windows NT family of operating systems that extends NTVDM to provide limited support for running legacy 16-bit programs written for Windows 3.x or earlier. There is a similar subsystem, known as WoW64, on 64-bit Windows versions that runs 32-bit programs. Background Many 16-bit Windows legacy programs can run without changes on newer 32-bit editions of Windows. The reason designers made this possible was to allow software developers time to remedy their software during the industry transition from Windows 3.1x to Windows 95 and later, without restricting the ability for the operating system to be upgraded to a current version before all programs used by a customer had been taken care of. The Windows 9x series of operating systems, reflecting their roots in DOS, functioned as hybrid 16- and 32-bit systems in the sense that the underlying operating system was not truly 32-bit, and therefore could run 16-bit software natively without requiring any special emulation; Windows NT operating systems differ significantly from Windows 9x in their architecture, and therefore require a more complex solution. Two separate strategies are used in order to let 16-bit programs run on 32-bit versions of Windows (with some runtime limitations). They are called thunking and shimming. Thunking The WOW subsystem of the operating system in order to provide support for 16-bit pointers, memory models and address space. All 16-bit programs run by default in a single virtual DOS machine with shared memory space. However, they can be configured to run in their own separate memory space, in which case each 16-bit process has its own dedicated virtual machine. The separate memory space increases system stability by preventing buggy 16-bit programs from interfering with one another, at the expense of reduced 16-bit inter-process communication and increased memory utilization. This subsystem is available in 32-bit editions of Windows NT only. The 64-bit editions (including Windows Server 2008 R2 and later which only have 64-bit editions) cannot run 16-bit software without third-party emulation software (e.g. DOSBox). With Windows 11 dropping support for 32-bit IA-32 processors, development of this subsystem has been discontinued. The WOWEXEC.EXE process on a Windows NT system facilitates Windows-on-Windows. In addition to Windows-on-Windows emulating the Windows 95 to Windows 98 kernels, the WIN.COM file emulates a Windows 3.x kernel for NTVDM, which runs the 16-bit DOS-based Windows applications on Windows NT. Shimming Application compatibility issues, notably around long filenames, multiple users and the concept of least privilege, may prevent some applications from working. For example, they may incorrectly assume full write access to the whole file system whereas NTFS security is in place. When the Windows 95 line of operating systems was designed, a key requirement was for the file system to keep backward compatibility with 8.3 filenames to allow legacy applications to continue to work on the platform. Windows 95 and later operating systems therefore support a compatibility mode whereby both a long filename and a short filename are stored in the File Allocation Table. Furthermore, legacy applications that attempt to access hardware directly cannot do so in user mode. Legacy applications may also fail if system configuration files from the DOS and Windows 9x era are not present in Windows NT based kernels, hence the reason for zero-length versions of files like AUTOEXEC.BAT and CONFIG.SYS having to be carried forward on operating systems that do not use them. A considerable number of shims are present in the application compatibility layer of later versions of Windows to intercept and modify API calls made by legacy applications that were written with a different set of assumptions and operating system best practices in mind. These fixes are updated from time-to-time as issues are discovered in popular legacy applications that are still in use. See also Wine (software) References External links Windows NT subsystems What are NTVDM and WOW? Optimize How Windows 7 Runs 16-Bit and MS-DOS-Based Programs Windows components

Operating System (OS)

Legacy system In computing, a legacy system is an old method, technology, computer system, or application program, "of, relating to, or being a previous or outdated computer system," yet still in use. Often referencing a system as "legacy" means that it paved the way for the standards that would follow it. This can also imply that the system is out of date or in need of replacement. Legacy code is old computer source code. It could simply refer to an organization's existing code base which has been written over many years, or it could imply a codebase that is in some respect obsolete or supporting something obsolete. Long-lived code is susceptible to software rot, where changes to the runtime environment, or surrounding software or hardware may require maintenance or emulation of some kind to keep working. Legacy code may be present to support legacy hardware, a separate legacy system, or a legacy customer using an old feature or software version. While the term usually refers to source code, it can also apply to executable code that no longer runs on a later version of a system, or requires a compatibility layer to do so. An example would be a classic Macintosh application which will not run natively on macOS, but runs inside the Classic environment, or a Win16 application running on Windows XP using the Windows on Windows feature in XP. An example of legacy hardware are legacy ports like PS/2 and VGA ports, and CPUs with older, incompatible instruction sets (with e.g. newer operating systems). Examples in legacy software include legacy file formats like .swf for Adobe Shockwave or .123 for Lotus 1-2-3, and text files encoded with legacy character encodings like EBCDIC. Overview The first use of the term legacy to describe computer systems probably occurred in the 1960s. By the 1980s it was commonly used to refer to existing computer systems to distinguish them from the design and implementation of new systems. Legacy was often heard during a conversion process, for example, when moving data from the legacy system to a new database. While this term may indicate that some engineers may feel that a system is out of date, a legacy system can continue to be used for a variety of reasons. It may simply be that the system still provides for the users' needs. In addition, the decision to keep an old system may be influenced by economic reasons such as return on investment challenges or vendor lock-in, the inherent challenges of change management, or a variety of other reasons other than functionality. Backward compatibility (such as the ability of newer systems to handle legacy file formats and character encodings) is a goal that software developers often include in their work. Even if it is no longer used, a legacy system may continue to impact the organization due to its historical role. Historic data may not have been converted into the new system format and may exist within the new system with the use of a customized schema crosswalk, or may exist only in a data warehouse. In either case, the effect on business intelligence and operational reporting can be significant. A legacy system may include procedures or terminology which are no longer relevant in the current context, and may hinder or confuse understanding of the methods or technologies used. Organizations can have compelling reasons for keeping a legacy system, such as: The system works satisfactorily, and the owner sees no reason to change it. The costs of redesigning or replacing the system are prohibitive because it is large, monolithic, and/or complex. Retraining on a new system would be costly in lost time and money, compared to the anticipated appreciable benefits of replacing it (which may be zero). The system requires near-constant availability, so it cannot be taken out of service, and the cost of designing a new system with a similar availability level is high. Examples include systems to handle customers' accounts in banks, computer reservations systems, air traffic control, energy distribution (power grids), nuclear power plants, military defense installations, and systems such as the TOPS database. The way that the system works is not well understood. Such a situation can occur when the designers of the system have left the organization, and the system has either not been fully documented or documentation has been lost. The user expects that the system can easily be replaced when this becomes necessary. Newer systems perform undesirable (especially for individual or non-institutional users) secondary functions such as a) tracking and reporting of user activity and/or b) automatic updating that creates "back-door" security vulnerabilities and leaves end users dependent on the good faith and honesty of the vendor providing the updates. This problem is especially acute when these secondary functions of a newer system cannot be disabled. Problems posed by legacy computing Legacy systems are considered to be potentially problematic by some software engineers for several reasons. If legacy software runs on only antiquated hardware, the cost of maintaining the system may eventually outweigh the cost of replacing both the software and hardware unless some form of emulation or backward compatibility allows the software to run on new hardware. These systems can be hard to maintain, improve, and expand because there is a general lack of understanding of the system; the staff who were experts on it have retired or forgotten what they knew about it, and staff who entered the field after it became "legacy" never learned about it in the first place. This can be worsened by lack or loss of documentation. Comair airline company fired its CEO in 2004 due to the failure of an antiquated legacy crew scheduling system that ran into a limitation not known to anyone in the company. Legacy systems may have vulnerabilities in older operating systems or applications due to lack of security patches being available or applied. There can also be production configurations that cause security problems. These issues can put the legacy system at risk of being compromised by attackers or knowledgeable insiders. Integration with newer systems may also be difficult because new software may use completely different technologies. Integration across technology is quite common in computing, but integration between newer technologies and substantially older ones is not common. There may simply not be sufficient demand for integration technology to be developed. Some of this "glue" code is occasionally developed by vendors and enthusiasts of particular legacy technologies. Budgetary constraints often lead corporations to not address the need of replacement or migration of a legacy system. However, companies often don't consider the increasing supportability costs (people, software and hardware, all mentioned above) and do not take into consideration the enormous loss of capability or business continuity if the legacy system were to fail. Once these considerations are well understood, then based on the proven ROI of a new, more secure, updated technology stack platform is not as costly as the alternative—and the budget is found. Due to the fact that most legacy programmers are entering retirement age and the number of young engineers replacing them is very small, there is an alarming shortage of available workforce. This in turn results in difficulty in maintaining legacy systems, as well as an increase in costs of procuring experienced programmers. Improvements on legacy software systems Where it is impossible to replace legacy systems through the practice of application retirement, it is still possible to enhance (or "re-face") them. Most development often goes into adding new interfaces to a legacy system. The most prominent technique is to provide a Web-based interface to a terminal-based mainframe application. This may reduce staff productivity due to slower response times and slower mouse-based operator actions, yet it is often seen as an "upgrade", because the interface style is familiar to unskilled users and is easy for them to use. John McCormick discusses such strategies that involve middleware. Printing improvements are problematic because legacy software systems often add no formatting instructions, or they use protocols that are not usable in modern PC/Windows printers. A print server can be used to intercept the data and translate it to a more modern code. Rich Text Format (RTF) or PostScript documents may be created in the legacy application and then interpreted at a PC before being printed. Biometric security measures are difficult to implement on legacy systems. A workable solution is to use a Telnet or HTTP proxy server to sit between users and the mainframe to implement secure access to the legacy application. The change being undertaken in some organizations is to switch to automated business process (ABP) software which generates complete systems. These systems can then interface to the organizations' legacy systems and use them as data repositories. This approach can provide a number of significant benefits: the users are insulated from the inefficiencies of their legacy systems, and the changes can be incorporated quickly and easily in the ABP software. Model-driven reverse and forward engineering approaches can be also used for the improvement of legacy software. NASA example Andreas Hein, from the Technical University of Munich, researched the use of legacy systems in space exploration. According to Hein, legacy systems are attractive for reuse if an organization has the capabilities for verification, validation, testing, and operational history. These capabilities must be integrated into various software life cycle phases such as development, implementation, usage, or maintenance. For software systems, the capability to use and maintain the system are crucial. Otherwise the system will become less and less understandable and maintainable. According to Hein, verification, validation, testing, and operational history increases the confidence in a system's reliability and quality. However, accumulating this history is often expensive. NASA's now retired Space Shuttle program used a large amount of 1970s-era technology. Replacement was cost-prohibitive because of the expensive requirement for flight certification. The original hardware completed the expensive integration and certification requirement for flight, but any new equipment would have had to go through that entire process again. This long and detailed process required extensive tests of the new components in their new configurations before a single unit could be used in the Space Shuttle program. Thus any new system that started the certification process becomes a de facto legacy system by the time it is approved for flight. Additionally, the entire Space Shuttle system, including ground and launch vehicle assets, was designed to work together as a closed system. Since the specifications did not change, all of the certified systems and components performed well in the roles for which they were designed. Even before the Shuttle was scheduled to be retired in 2010, NASA found it advantageous to keep using many pieces of 1970s technology rather than to upgrade those systems and recertify the new components. Perspectives on legacy code Some in the software engineering prefer to describe "legacy code" without the connotation of being obsolete. Among the most prevalent neutral conceptions are source code inherited from someone else and source code inherited from an older version of the software. Eli Lopian, CEO of Typemock, has defined it as "code that developers are afraid to change". Michael Feathers introduced a definition of legacy code as code without tests, which reflects the perspective of legacy code being difficult to work with in part due to a lack of automated regression tests. He also defined characterization tests to start putting legacy code under test. Ginny Hendry characterized creation of code as a challenge to current coders to create code that is "like other legacies in our lives—like the antiques, heirlooms, and stories that are cherished and lovingly passed down from one generation to the next. What if legacy code was something we took pride in?". Additional uses of the term Legacy in computing The term legacy support is often used in conjunction with legacy systems. The term may refer to a feature of modern software. For example, Operating systems with "legacy support" can detect and use older hardware. The term may also be used to refer to a business function; e.g. a software or hardware vendor that is supporting, or providing software maintenance, for older products. A "legacy" product may be a product that is no longer sold, has lost substantial market share, or is a version of a product that is not current. A legacy product may have some advantage over a modern product making it appealing for customers to keep it around. A product is only truly "obsolete" if it has an advantage to nobody—if no person making a rational decision would choose to acquire it new. The term "legacy mode" often refers specifically to backward compatibility. A software product that is capable of performing as though it were a previous version of itself, is said to be "running in legacy mode." This kind of feature is common in operating systems and internet browsers, where many applications depend on these underlying components. The computer mainframe era saw many applications running in legacy mode. In the modern business computing environment, n-tier, or 3-tier architectures are more difficult to place into legacy mode as they include many components making up a single system. Virtualization technology is a recent innovation allowing legacy systems to continue to operate on modern hardware by running older operating systems and browsers on a software system that emulates legacy hardware. Brownfield architecture Programmers have borrowed the term brownfield from the construction industry, where previously developed land (often polluted and abandoned) is described as brownfield. Brownfield architecture is a type of software or network architecture that incorporates legacy systems. Brownfield deployment is an upgrade or addition to an existing software or network architecture that retains legacy components. Alternative view There is an alternate favorable opinion—growing since the end of the Dotcom bubble in 1999—that legacy systems are simply computer systems in working use: IT analysts estimate that the cost of replacing business logic is about five times that of reuse, even discounting the risk of system failures and security breaches. Ideally, businesses would never have to rewrite most core business logic: debits = credits is a perennial requirement. The IT industry is responding with "legacy modernization" and "legacy transformation": refurbishing existing business logic with new user interfaces, sometimes using screen scraping and service-enabled access through web services. These techniques allow organizations to understand their existing code assets (using discovery tools), provide new user and application interfaces to existing code, improve workflow, contain costs, minimize risk, and enjoy classic qualities of service (near 100% uptime, security, scalability, etc.). This trend also invites reflection on what makes legacy systems so durable. Technologists are relearning the importance of sound architecture from the start, to avoid costly and risky rewrites. The most common legacy systems tend to be those which embraced well-known IT architectural principles, with careful planning and strict methodology during implementation. Poorly designed systems often don't last, both because they wear out and because their inherent faults invite replacement. Thus, many organizations are rediscovering the value of both their legacy systems and the theoretical underpinnings of those systems. See also Application retirement Software rot Data migration Deprecation Digital dark age Legacy encoding Legacy-free PC Legacy port Software archaeology Software brittleness Software entropy Stovepipe system References Further reading A.M. Hein, How to Assess Heritage Systems in the Early Phases? SECESA 2014, 08-10 October 2014, University of Stuttgart Germany "Tips and Tricks for Legacy Hardware" by Danny Budzinski, Control Design Magazine, January 2011 "Comair's Christmas Disaster: Bound To Fail" by Stephanie Overby, CIO Magazine, May 1, 2005 "The Failure of the Digital Computer" by Adam N. Rosenberg "The Danger of Legacy Systems" by Steve R. Smith, May 3, 2011. External links System Technological change

Operating System (OS)

Embedded system An embedded system is a computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is embedded as part of a complete device often including electrical or electronic hardware and mechanical parts. Because an embedded system typically controls physical operations of the machine that it is embedded within, it often has real-time computing constraints. Embedded systems control many devices in common use today. it was estimated that ninety-eight percent of all microprocessors manufactured were used in embedded systems. Modern embedded systems are often based on microcontrollers (i.e. microprocessors with integrated memory and peripheral interfaces), but ordinary microprocessors (using external chips for memory and peripheral interface circuits) are also common, especially in more complex systems. In either case, the processor(s) used may be types ranging from general purpose to those specialized in a certain class of computations, or even custom designed for the application at hand. A common standard class of dedicated processors is the digital signal processor (DSP). Since the embedded system is dedicated to specific tasks, design engineers can optimize it to reduce the size and cost of the product and increase the reliability and performance. Some embedded systems are mass-produced, benefiting from economies of scale. Embedded systems range in size from portable personal devices such as digital watches and MP3 players to bigger machines like home appliances, industrial assembly lines, robots, transport vehicles, traffic light controllers, and medical imaging systems. Often they constitute subsystems of other machines like avionics in aircraft. Large installations like factories, pipelines and electrical grids rely on multiple embedded systems networked together. Generalized through software customization, embedded systems such as programmable logic controllers frequently comprise their functional units. Embedded systems range from those low in complexity, with a single microcontroller chip, to very high with multiple units, peripherals and networks, which may reside in equipment racks or across large geographical areas connected via long-distance communications lines. History Background The origins of the microprocessor and the microcontroller can be traced back to the MOS integrated circuit, which is an integrated circuit chip fabricated from MOSFETs (metal-oxide-semiconductor field-effect transistors) and was developed in the early 1960s. By 1964, MOS chips had reached higher transistor density and lower manufacturing costs than bipolar chips. MOS chips further increased in complexity at a rate predicted by Moore's law, leading to large-scale integration (LSI) with hundreds of transistors on a single MOS chip by the late 1960s. The application of MOS LSI chips to computing was the basis for the first microprocessors, as engineers began recognizing that a complete computer processor system could be contained on several MOS LSI chips. The first multi-chip microprocessors, the Four-Phase Systems AL1 in 1969 and the Garrett AiResearch MP944 in 1970, were developed with multiple MOS LSI chips. The first single-chip microprocessor was the Intel 4004, released in 1971. It was developed by Federico Faggin, using his silicon-gate MOS technology, along with Intel engineers Marcian Hoff and Stan Mazor, and Busicom engineer Masatoshi Shima. Development One of the first recognizably modern embedded systems was the Apollo Guidance Computer, developed ca. 1965 by Charles Stark Draper at the MIT Instrumentation Laboratory. At the project's inception, the Apollo guidance computer was considered the riskiest item in the Apollo project as it employed the then newly developed monolithic integrated circuits to reduce the computer's size and weight. An early mass-produced embedded system was the Autonetics D-17 guidance computer for the Minuteman missile, released in 1961. When the Minuteman II went into production in 1966, the D-17 was replaced with a new computer that represented the first high-volume use of integrated circuits. Since these early applications in the 1960s, embedded systems have come down in price and there has been a dramatic rise in processing power and functionality. An early microprocessor, the Intel 4004 (released in 1971), was designed for calculators and other small systems but still required external memory and support chips. By the early 1980s, memory, input and output system components had been integrated into the same chip as the processor forming a microcontroller. Microcontrollers find applications where a general-purpose computer would be too costly. As the cost of microprocessors and microcontrollers fell the prevalence of embedded systems increased. Today, a comparatively low-cost microcontroller may be programmed to fulfill the same role as a large number of separate components. With microcontrollers, it became feasible to replace, even in consumer products, expensive knob-based analog components such as potentiometers and variable capacitors with up/down buttons or knobs read out by a microprocessor. Although in this context an embedded system is usually more complex than a traditional solution, most of the complexity is contained within the microcontroller itself. Very few additional components may be needed and most of the design effort is in the software. Software prototype and test can be quicker compared with the design and construction of a new circuit not using an embedded processor. Applications Embedded systems are commonly found in consumer, industrial, automotive, home appliances, medical, telecommunication, commercial and military applications. Telecommunications systems employ numerous embedded systems from telephone switches for the network to cell phones at the end user. Computer networking uses dedicated routers and network bridges to route data. Consumer electronics include MP3 players, television sets, mobile phones, video game consoles, digital cameras, GPS receivers, and printers. Household appliances, such as microwave ovens, washing machines and dishwashers, include embedded systems to provide flexibility, efficiency and features. Advanced HVAC systems use networked thermostats to more accurately and efficiently control temperature that can change by time of day and season. Home automation uses wired- and wireless-networking that can be used to control lights, climate, security, audio/visual, surveillance, etc., all of which use embedded devices for sensing and controlling. Transportation systems from flight to automobiles increasingly use embedded systems. New airplanes contain advanced avionics such as inertial guidance systems and GPS receivers that also have considerable safety requirements. Various electric motors — brushless DC motors, induction motors and DC motors — use electronic motor controllers. Automobiles, electric vehicles, and hybrid vehicles increasingly use embedded systems to maximize efficiency and reduce pollution. Other automotive safety systems using embedded systems include anti-lock braking system (ABS), Electronic Stability Control (ESC/ESP), traction control (TCS) and automatic four-wheel drive. Medical equipment uses embedded systems for monitoring, and various medical imaging (PET, Single-photon emission computed tomography (SPECT), CT, and MRI) for non-invasive internal inspections. Embedded systems within medical equipment are often powered by industrial computers. Embedded systems are used for safety-critical systems. Unless connected to wired or wireless networks via on-chip 3G cellular or other methods for IoT monitoring and control purposes, these systems can be isolated from hacking and thus be more secure. For fire safety, the systems can be designed to have a greater ability to handle higher temperatures and continue to operate. In dealing with security, the embedded systems can be self-sufficient and be able to deal with cut electrical and communication systems. Miniature wireless devices called motes are networked wireless sensors. Wireless sensor networking makes use of miniaturization made possible by advanced IC design to couple full wireless subsystems to sophisticated sensors, enabling people and companies to measure a myriad of things in the physical world and act on this information through monitoring and control systems. These motes are completely self-contained and will typically run off a battery source for years before the batteries need to be changed or charged. Characteristics Embedded systems are designed to do some specific task, rather than be a general-purpose computer for multiple tasks. Some also have real-time performance constraints that must be met, for reasons such as safety and usability; others may have low or no performance requirements, allowing the system hardware to be simplified to reduce costs. Embedded systems are not always standalone devices. Many embedded systems consist of small parts within a larger device that serves a more general purpose. For example, the Gibson Robot Guitar features an embedded system for tuning the strings, but the overall purpose of the Robot Guitar is, of course, to play music. Similarly, an embedded system in an automobile provides a specific function as a subsystem of the car itself. The program instructions written for embedded systems are referred to as firmware, and are stored in read-only memory or flash memory chips. They run with limited computer hardware resources: little memory, small or non-existent keyboard or screen. User interfaces Embedded systems range from no user interface at all, in systems dedicated only to one task, to complex graphical user interfaces that resemble modern computer desktop operating systems. Simple embedded devices use buttons, LEDs, graphic or character LCDs (HD44780 LCD for example) with a simple menu system. More sophisticated devices that use a graphical screen with touch sensing or screen-edge soft keys provide flexibility while minimizing space used: the meaning of the buttons can change with the screen, and selection involves the natural behavior of pointing at what is desired. Some systems provide user interface remotely with the help of a serial (e.g. RS-232) or network (e.g. Ethernet) connection. This approach extends the capabilities of the embedded system, avoids the cost of a display, simplifies BSP and allows designers to build a rich user interface on the PC. A good example of this is the combination of an Embedded HTTP server running on an embedded device (such as an IP camera or a network router). The user interface is displayed in a web browser on a PC connected to the device. Processors in embedded systems Examples of properties of typical embedded computers, when compared with general-purpose counterparts, are low power consumption, small size, rugged operating ranges, and low per-unit cost. This comes at the price of limited processing resources. Numerous microcontrollers have been developed for embedded systems use. General-purpose microprocessors are also used in embedded systems, but generally, require more support circuitry than microcontrollers. Ready-made computer boards PC/104 and PC/104+ are examples of standards for ready-made computer boards intended for small, low-volume embedded and ruggedized systems. These are mostly x86-based and often physically small compared to a standard PC, although still quite large compared to most simple (8/16-bit) embedded systems. They may use DOS, Linux, NetBSD, or an embedded real-time operating system (RTOS) such as MicroC/OS-II, QNX or VxWorks. In certain applications, where small size or power efficiency are not primary concerns, the components used may be compatible with those used in general-purpose x86 personal computers. Boards such as the VIA EPIA range help to bridge the gap by being PC-compatible but highly integrated, physically smaller or have other attributes making them attractive to embedded engineers. The advantage of this approach is that low-cost commodity components may be used along with the same software development tools used for general software development. Systems built in this way are still regarded as embedded since they are integrated into larger devices and fulfill a single role. Examples of devices that may adopt this approach are ATMs and arcade machines, which contain code specific to the application. However, most ready-made embedded systems boards are not PC-centered and do not use the ISA or PCI busses. When a system-on-a-chip processor is involved, there may be little benefit to having a standardized bus connecting discrete components, and the environment for both hardware and software tools may be very different. One common design style uses a small system module, perhaps the size of a business card, holding high density BGA chips such as an ARM-based system-on-a-chip processor and peripherals, external flash memory for storage, and DRAM for runtime memory. The module vendor will usually provide boot software and make sure there is a selection of operating systems, usually including Linux and some real-time choices. These modules can be manufactured in high volume, by organizations familiar with their specialized testing issues, and combined with much lower volume custom mainboards with application-specific external peripherals. Prominent examples of this approach include Arduino and Raspberry Pi. ASIC and FPGA SoC solutions A system on a chip (SoC) contains a complete system - consisting of multiple processors, multipliers, caches, even different types of memory and commonly various peripherals like interfaces for wired or wireless communication on a single chip. Often graphics processing units (GPU) and DSPs are included such chips. SoCs can be implemented as an application-specific integrated circuit (ASIC) or using a field-programmable gate array (FPGA) which typically can be reconfigured. ASIC implementations are common for very-high-volume embedded systems like mobile phones and smartphones. ASIC or FPGA implementations may be used for not-so-high-volume embedded systems with special needs in kind of signal processing performance, interfaces and reliability, like in avionics. Peripherals Embedded systems talk with the outside world via peripherals, such as: Serial communication interfaces (SCI): RS-232, RS-422, RS-485, etc. Synchronous Serial Interface: I2C, SPI, SSC and ESSI (Enhanced Synchronous Serial Interface) Universal Serial Bus (USB) Media cards (SD cards, CompactFlash, etc.) Network interface controller: Ethernet, WiFi, etc. Fieldbuses: CAN bus, LIN-Bus, PROFIBUS, etc. Timers: Phase-locked loops, programmable interval timers General Purpose Input/Output (GPIO) Analog-to-digital and digital-to-analog converters) Debugging: JTAG, In-system programming, background debug mode interface port, BITP, and DB9 ports. Tools As with other software, embedded system designers use compilers, assemblers, and debuggers to develop embedded system software. However, they may also use more specific tools: In circuit debuggers or emulators (see next section). Utilities to add a checksum or CRC to a program, so the embedded system can check if the program is valid. For systems using digital signal processing, developers may use a computational notebook to simulate the mathematics. System-level modeling and simulation tools help designers to construct simulation models of a system with hardware components such as processors, memories, DMA, interfaces, buses and software behavior flow as a state diagram or flow diagram using configurable library blocks. Simulation is conducted to select the right components by performing power vs. performance trade-offs, reliability analysis and bottleneck analysis. Typical reports that help a designer to make architecture decisions include application latency, device throughput, device utilization, power consumption of the full system as well as device-level power consumption. A model-based development tool creates and simulates graphical data flow and UML state chart diagrams of components like digital filters, motor controllers, communication protocol decoding and multi-rate tasks. Custom compilers and linkers may be used to optimize specialized hardware. An embedded system may have its own special language or design tool, or add enhancements to an existing language such as Forth or Basic. Another alternative is to add a RTOS or embedded operating system Modeling and code generating tools often based on state machines Software tools can come from several sources: Software companies that specialize in the embedded market Ported from the GNU software development tools Sometimes, development tools for a personal computer can be used if the embedded processor is a close relative to a common PC processor As the complexity of embedded systems grows, higher-level tools and operating systems are migrating into machinery where it makes sense. For example, cellphones, personal digital assistants and other consumer computers often need significant software that is purchased or provided by a person other than the manufacturer of the electronics. In these systems, an open programming environment such as Linux, NetBSD, OSGi or Embedded Java is required so that the third-party software provider can sell to a large market. Debugging Embedded debugging may be performed at different levels, depending on the facilities available. Considerations include: does it slow down the main application, how close is the debugged system or application to the actual system or application, how expressive are the triggers that can be set for debugging (e.g., inspecting the memory when a particular program counter value is reached), and what can be inspected in the debugging process (such as, only memory, or memory and registers, etc.). From simplest to most sophisticated debugging techniques and systems be roughly grouped into the following areas: Interactive resident debugging, using the simple shell provided by the embedded operating system (e.g. Forth and Basic) Software-only debuggers have the benefit that they do not need any hardware modification but have to carefully control what they record in order to conserve time and storage space. External debugging using logging or serial port output to trace operation using either a monitor in flash or using a debug server like the Remedy Debugger that even works for heterogeneous multicore systems. An in-circuit debugger (ICD), a hardware device that connects to the microprocessor via a JTAG or Nexus interface. This allows the operation of the microprocessor to be controlled externally, but is typically restricted to specific debugging capabilities in the processor. An in-circuit emulator (ICE) replaces the microprocessor with a simulated equivalent, providing full control over all aspects of the microprocessor. A complete emulator provides a simulation of all aspects of the hardware, allowing all of it to be controlled and modified, and allowing debugging on a normal PC. The downsides are expense and slow operation, in some cases up to 100 times slower than the final system. For SoC designs, the typical approach is to verify and debug the design on an FPGA prototype board. Tools such as Certus are used to insert probes in the FPGA implementation that make signals available for observation. This is used to debug hardware, firmware and software interactions across multiple FPGAs in an implementation with capabilities similar to a logic analyzer. Unless restricted to external debugging, the programmer can typically load and run software through the tools, view the code running in the processor, and start or stop its operation. The view of the code may be as HLL source-code, assembly code or mixture of both. Because an embedded system is often composed of a wide variety of elements, the debugging strategy may vary. For instance, debugging a software- (and microprocessor-) centric embedded system is different from debugging an embedded system where most of the processing is performed by peripherals (DSP, FPGA, and co-processor). An increasing number of embedded systems today use more than one single processor core. A common problem with multi-core development is the proper synchronization of software execution. In this case, the embedded system design may wish to check the data traffic on the busses between the processor cores, which requires very low-level debugging, at signal/bus level, with a logic analyzer, for instance. Tracing Real-time operating systems often supports tracing of operating system events. A graphical view is presented by a host PC tool, based on a recording of the system behavior. The trace recording can be performed in software, by the RTOS, or by special tracing hardware. RTOS tracing allows developers to understand timing and performance issues of the software system and gives a good understanding of the high-level system behaviors. Reliability Embedded systems often reside in machines that are expected to run continuously for years without errors, and in some cases recover by themselves if an error occurs. Therefore, the software is usually developed and tested more carefully than that for personal computers, and unreliable mechanical moving parts such as disk drives, switches or buttons are avoided. Specific reliability issues may include: The system cannot safely be shut down for repair, or it is too inaccessible to repair. Examples include space systems, undersea cables, navigational beacons, bore-hole systems, and automobiles. The system must be kept running for safety reasons. "Limp modes" are less tolerable. Often backups are selected by an operator. Examples include aircraft navigation, reactor control systems, safety-critical chemical factory controls, train signals. The system will lose large amounts of money when shut down: Telephone switches, factory controls, bridge and elevator controls, funds transfer and market making, automated sales and service. A variety of techniques are used, sometimes in combination, to recover from errors—both software bugs such as memory leaks, and also soft errors in the hardware: watchdog timer that resets the computer unless the software periodically notifies the watchdog subsystems with redundant spares that can be switched over to software "limp modes" that provide partial function Designing with a Trusted Computing Base (TCB) architecture ensures a highly secure & reliable system environment A hypervisor designed for embedded systems is able to provide secure encapsulation for any subsystem component so that a compromised software component cannot interfere with other subsystems, or privileged-level system software. This encapsulation keeps faults from propagating from one subsystem to another, thereby improving reliability. This may also allow a subsystem to be automatically shut down and restarted on fault detection. Immunity-aware programming can help to produce more reliable embedded systems code, and a variety of guidelines and industry standards such as MISRA C/C++ are available to assist developers. These guidelines and coding rules aim to assist developers produce reliable, portable firmware in a number of different ways: typically by advising or mandating against coding practices which may lead to run-time errors (memory leaks, invalid pointer uses), use of run-time checks and exception handling (range/sanity checks, divide-by-zero and buffer index validity checks, default cases in logic checks), loop bounding, production of human-readable, well commented and well structured code, and avoiding language ambiguities which may lead to compiler-induced inconsistencies or side-effects (expression evaluation ordering, recursion, certain types of macro). These rules can often be used in conjunction with code static checkers and/or bounded model checking for functional verification purposes, and also assist in determination of code timing properties. High vs. low volume For high volume systems such as portable music players or mobile phones, minimizing cost is usually the primary design consideration. Engineers typically select hardware that is just “good enough” to implement the necessary functions. For low-volume or prototype embedded systems, general-purpose computers may be adapted by limiting the programs or by replacing the operating system with a RTOS. Embedded software architectures In 1978 National Electrical Manufacturers Association released a standard for programmable microcontrollers, including almost any computer-based controllers, such as single board computers, numerical, and event-based controllers. There are several different types of software architecture in common use today. Simple control loop In this design, the software simply has a loop. The loop calls subroutines, each of which manages a part of the hardware or software. Hence it is called a simple control loop or control loop. Interrupt-controlled system Some embedded systems are predominantly controlled by interrupts. This means that tasks performed by the system are triggered by different kinds of events; an interrupt could be generated, for example, by a timer in a predefined frequency, or by a serial port controller receiving a byte. These kinds of systems are used if event handlers need low latency, and the event handlers are short and simple. Usually, these kinds of systems run a simple task in a main loop also, but this task is not very sensitive to unexpected delays. Sometimes the interrupt handler will add longer tasks to a queue structure. Later, after the interrupt handler has finished, these tasks are executed by the main loop. This method brings the system close to a multitasking kernel with discrete processes. Cooperative multitasking A non-preemptive multitasking system is very similar to the simple control loop scheme, except that the loop is hidden in an API. The programmer defines a series of tasks, and each task gets its own environment to “run” in. When a task is idle, it calls an idle routine, usually called “pause”, “wait”, “yield”, “nop” (stands for no operation), etc. The advantages and disadvantages are similar to that of the control loop, except that adding new software is easier, by simply writing a new task, or adding to the queue. Preemptive multitasking or multi-threading In this type of system, a low-level piece of code switches between tasks or threads based on a timer (connected to an interrupt). This is the level at which the system is generally considered to have an "operating system" kernel. Depending on how much functionality is required, it introduces more or less of the complexities of managing multiple tasks running conceptually in parallel. As any code can potentially damage the data of another task (except in larger systems using an MMU) programs must be carefully designed and tested, and access to shared data must be controlled by some synchronization strategy, such as message queues, semaphores or a non-blocking synchronization scheme. Because of these complexities, it is common for organizations to use a RTOS, allowing the application programmers to concentrate on device functionality rather than operating system services, at least for large systems; smaller systems often cannot afford the overhead associated with a generic real-time system, due to limitations regarding memory size, performance, or battery life. The choice that an RTOS is required brings in its own issues, however, as the selection must be made prior to starting to the application development process. This timing forces developers to choose the embedded operating system for their device based upon current requirements and so restricts future options to a large extent. The restriction of future options becomes more of an issue as product life decreases. Additionally, the level of complexity is continuously growing as devices are required to manage variables such as serial, USB, TCP/IP, Bluetooth, Wireless LAN, trunk radio, multiple channels, data and voice, enhanced graphics, multiple states, multiple threads, numerous wait states and so on. These trends are leading to the uptake of embedded middleware in addition to a RTOS. Microkernels and exokernels A microkernel is a logical step up from a real-time OS. The usual arrangement is that the operating system kernel allocates memory and switches the CPU to different threads of execution. User-mode processes implement major functions such as file systems, network interfaces, etc. In general, microkernels succeed when task switching and intertask communication is fast and fail when they are slow. Exokernels communicate efficiently by normal subroutine calls. The hardware and all the software in the system are available to and extensible by application programmers. Monolithic kernels In this case, a relatively large kernel with sophisticated capabilities is adapted to suit an embedded environment. This gives programmers an environment similar to a desktop operating system like Linux or Microsoft Windows, and is therefore very productive for development; on the downside, it requires considerably more hardware resources, is often more expensive, and, because of the complexity of these kernels, can be less predictable and reliable. Common examples of embedded monolithic kernels are embedded Linux, VXWorks and Windows CE. Despite the increased cost in hardware, this type of embedded system is increasing in popularity, especially on the more powerful embedded devices such as wireless routers and GPS navigation systems. Here are some of the reasons: Ports to common embedded chip sets are available. They permit re-use of publicly available code for device drivers, web servers, firewalls, and other code. Development systems can start out with broad feature-sets, and then the distribution can be configured to exclude unneeded functionality, and save the expense of the memory that it would consume. Many engineers believe that running application code in user mode is more reliable and easier to debug, thus making the development process easier and the code more portable. Features requiring faster response than can be guaranteed can often be placed in hardware. Additional software components In addition to the core operating system, many embedded systems have additional upper-layer software components. These components consist of networking protocol stacks like CAN, TCP/IP, FTP, HTTP, and HTTPS, and also included storage capabilities like FAT and flash memory management systems. If the embedded device has audio and video capabilities, then the appropriate drivers and codecs will be present in the system. In the case of the monolithic kernels, many of these software layers are included. In the RTOS category, the availability of the additional software components depends upon the commercial offering. Domain-specific architectures In the automotive sector, AUTOSAR is a standard architecture for embedded software. See also Communications server Cyber-physical system Electronic control unit Hypervisor Information appliance Integrated development environment Photonically Optimized Embedded Microprocessors Silicon compiler Software engineering System on module Ubiquitous computing Notes References Further reading External links Embedded Systems course with mbed YouTube, ongoing from 2015 Trends in Cyber Security and Embedded Systems Dan Geer, November 2013 Modern Embedded Systems Programming Video Course YouTube, ongoing from 2013 Embedded Systems Week (ESWEEK) yearly event with conferences, workshops and tutorials covering all aspects of embedded systems and software Workshop on Embedded and Cyber-Physical Systems Education, workshop covering educational aspects of embedded systems

Operating System (OS)

OS-level virtualization OS-level virtualization is an operating system (OS) paradigm in which the kernel allows the existence of multiple isolated user space instances, called containers (LXC, Solaris containers, Docker, Podman), zones (Solaris containers), virtual private servers (OpenVZ), partitions, virtual environments (VEs), virtual kernels (DragonFly BSD), or jails (FreeBSD jail or chroot jail). Such instances may look like real computers from the point of view of programs running in them. A computer program running on an ordinary operating system can see all resources (connected devices, files and folders, network shares, CPU power, quantifiable hardware capabilities) of that computer. However, programs running inside of a container can only see the container's contents and devices assigned to the container. On Unix-like operating systems, this feature can be seen as an advanced implementation of the standard chroot mechanism, which changes the apparent root folder for the current running process and its children. In addition to isolation mechanisms, the kernel often provides resource-management features to limit the impact of one container's activities on other containers. Linux containers are all based on the virtualization, isolation, and resource management mechanisms provided by the Linux kernel, notably Linux namespaces and cgroups. The term container, while most popularly referring to OS-level virtualization systems, is sometimes ambiguously used to refer to fuller virtual machine environments operating in varying degrees of concert with the host OS, e.g. Microsoft's Hyper-V containers. Operation On ordinary operating systems for personal computers, a computer program can see (even though it might not be able to access) all the system's resources. They include: Hardware capabilities that can be employed, such as the CPU and the network connection Data that can be read or written, such as files, folders and network shares Connected peripherals it can interact with, such as webcam, printer, scanner, or fax The operating system may be able to allow or deny access to such resources based on which program requests them and the user account in the context of which it runs. The operating system may also hide those resources, so that when the computer program enumerates them, they do not appear in the enumeration results. Nevertheless, from a programming point of view, the computer program has interacted with those resources and the operating system has managed an act of interaction. With operating-system-virtualization, or containerization, it is possible to run programs within containers, to which only parts of these resources are allocated. A program expecting to see the whole computer, once run inside a container, can only see the allocated resources and believes them to be all that is available. Several containers can be created on each operating system, to each of which a subset of the computer's resources is allocated. Each container may contain any number of computer programs. These programs may run concurrently or separately, and may even interact with one another. Containerization has similarities to application virtualization: In the latter, only one computer program is placed in an isolated container and the isolation applies to file system only. Uses Operating-system-level virtualization is commonly used in virtual hosting environments, where it is useful for securely allocating finite hardware resources among a large number of mutually-distrusting users. System administrators may also use it for consolidating server hardware by moving services on separate hosts into containers on the one server. Other typical scenarios include separating several programs to separate containers for improved security, hardware independence, and added resource management features. The improved security provided by the use of a chroot mechanism, however, is nowhere near ironclad. Operating-system-level virtualization implementations capable of live migration can also be used for dynamic load balancing of containers between nodes in a cluster. Overhead Operating-system-level virtualization usually imposes less overhead than full virtualization because programs in OS-level virtual partitions use the operating system's normal system call interface and do not need to be subjected to emulation or be run in an intermediate virtual machine, as is the case with full virtualization (such as VMware ESXi, QEMU, or Hyper-V) and paravirtualization (such as Xen or User-mode Linux). This form of virtualization also does not require hardware support for efficient performance. Flexibility Operating-system-level virtualization is not as flexible as other virtualization approaches since it cannot host a guest operating system different from the host one, or a different guest kernel. For example, with Linux, different distributions are fine, but other operating systems such as Windows cannot be hosted. Operating systems using variable input systematics are subject to limitations within the virtualized architecture. Adaptation methods including cloud-server relay analytics maintain the OS-level virtual environment within these applications. Solaris partially overcomes the limitation described above with its branded zones feature, which provides the ability to run an environment within a container that emulates an older Solaris 8 or 9 version in a Solaris 10 host. Linux branded zones (referred to as "lx" branded zones) are also available on x86-based Solaris systems, providing a complete Linux userspace and support for the execution of Linux applications; additionally, Solaris provides utilities needed to install Red Hat Enterprise Linux 3.x or CentOS 3.x Linux distributions inside "lx" zones. However, in 2010 Linux branded zones were removed from Solaris; in 2014 they were reintroduced in Illumos, which is the open source Solaris fork, supporting 32-bit Linux kernels. Storage Some implementations provide file-level copy-on-write (CoW) mechanisms. (Most commonly, a standard file system is shared between partitions, and those partitions that change the files automatically create their own copies.) This is easier to back up, more space-efficient and simpler to cache than the block-level copy-on-write schemes common on whole-system virtualizers. Whole-system virtualizers, however, can work with non-native file systems and create and roll back snapshots of the entire system state. Implementations Linux containers not listed above include: LXD, an alternative wrapper around LXC developed by Canonical Podman, a drop-in replacement for Docker Charliecloud, a set of container tools used on HPC systems Kata Containers MicroVM Platform Bottlerocket is a Linux-based open-source operating system that is purpose-built by Amazon Web Services for running containers on virtual machines or bare metal hosts See also Container orchestration Linux namespaces cgroups Sandbox (software development) Container Linux Hypervisor Portable application creators Open Container Initiative Separation kernel Serverless computing Snap package manager Storage hypervisor Virtual private server (VPS) Virtual resource partitioning Notes References External links An introduction to Virtualization A short intro to three different virtualization techniques Virtualization and Containerization of Application Infrastructure: A Comparison, June 22, 2015, by Mathijs Jeroen Scheepers Containers and persistent data, LWN.net, May 28, 2015, by Josh Berkus Virtualization software Operating system technology Operating system security Linux containerization Linux Linux kernel features

Operating System (OS)