Windows NT 4.0

Windows NT 4.0 (codenamed Shell Update Release or Tukwila) is a major version of Windows NT, which was released on 24 August 1996 as the successor to Windows NT 3.51 released a year before. It introduces the Windows 95 user interface to the Windows NT line and includes major architectural changes to the operating system such as moving a large part of the graphics subsystem to kernel mode and was the longest running version of Windows NT until Windows 2000's release four years later.
At launch, Windows NT 4.0 supported 486 and newer processors as well as MIPS, DEC Alpha and PowerPC. However, most of the ports were ultimately deprecated in the following years, with support for the last surviving non-x86 version for the DEC Alpha being dropped in August 1999.
This version originally launched in Workstation and Server editions. An Enterprise Edition of Windows NT Server 4.0 was released in 1997 and is designed for high-demand, high-traffic networks. The Terminal Server Edition (codenamed Hydra), introduced in 1998, allows users to log-in via a remote desktop client. Finally, Windows NT Embedded 4.0 (codenamed Impala) was launched in 1999, which allows developers to pick individual system components to build a custom version of Windows NT.
The Server and Workstation editions were succeeded by Windows 2000 on 17 February 2000, while the Embedded edition was succeeded by Windows XP Embedded on 28 November 2001. Windows NT 4.0 continued to be supported up to 2006 in various forms. A total of six Service Packs and a Security Rollup Package were released during its lifetime.
== History ==
Development on Windows NT 4.0 (known internally as SUR) followed on from Windows NT 3.51 and NewShell (the Shell Technology Preview project that had ported the Windows 95 shell to Windows NT). During the development of NT 3.51, both the NT 3.51 and NewShell versions of various system components had been developed in parallel and one could copy the NewShell versions of DLLs over their NT 3.51 system to install the Windows 95 user interface. Starting with NT 4.0, the NewShell components were used as a baseline from the start, and the shell was fundamentally working, but 
By the first available build of NT 4.0, Microsoft had already moved large parts of GDI and USER into kernel mode (the WIN32K.SYS kernel module), where previously they existed in user mode in the CSRSS process. This was done to improve performance, not only because graphical performance was generally sluggish on NT (and Microsoft had ambitions to bring NT into the graphical workstation market, beginning with NT 3.5's inclusion of OpenGL technology), but especially because the more graphically intensive Windows 95 shell highlighted the performance issues with running the graphics system in user mode. This did, however, cause a degradation in stability compared to Windows NT 3.x, since video drivers existed in the kernel's address space, meaning that a buggy driver could crash the entire system.
Windows NT 4.0 also included DirectDraw since build 1264, dropping support for DCI at the device-driver layer, though continuing to support the DCI Manager APIs for backwards compatibility purposes. 
== Editions ==
There are several editions of Windows NT 4.0:
* Workstation
* Server
** Enterprise Edition
** Terminal Server Edition
* Embedded
== Service Packs ==
There were 6 service packs released for Windows NT 4.0. Only Service Pack 1 was made available for the MIPS architecture, and Service Pack 2 was the final release for the PowerPC architecture. The last had been pulled by Microsoft due to a severe bug, which results in the revised Service Pack 6a. Microsoft had originally intended to release a seventh service pack for Windows NT 4.0, but eventually canceled it, and instead released an update rollup in 2001.Update on Windows NT 4.0 Service Pack 7, Windows NT Server. 19 April 2001. Archived from the original on 28 April 2001.Kerr, Rob. MS ditches Service Packs for Windows NT 4.0, The Register. 18 April 2001.
 Service Pack availability per architecture
Architecture	SP1	SP2	SP3	SP4	SP5	SP6	SRP
x86 	 	 	 	 	 	 	
DEC Alpha 	 	 	 	 	 	 	
PowerPC 	 	 	 	 	 	 	
MIPS 	 	 	 	 	 	 	
== Option Pack ==
The Windows NT 4.0 Optional Pack was released in 1997 and includes server solutions and clients for Windows NT 4.0 Workstation, Server and Windows 95, including Personal Web Server, Transaction Server, Message Queue Client, FrontPage 98 Server Extensions, Management Console, Script Debugger, Windows Scripting Host, Data Access Components and Internet Information Services 4.0.
Installing the Option Pack requires Service Pack 3 to be installed. Installing it on Service Pack 4 and later will cause setup to show an information that the option pack was not tested on Service Pack 4 yet, but lets the user continue.
== System requirements ==
The x86 version of Windows NT 4.0 requires a 486 processor, at least 16 MB of RAM, 110 MB of hard drive space (varies depending on components being installed), and a VGA or better display.ARCHIVED: What is Microsoft Windows NT?, University Information Technology Services. 18 January 2018. Windows NT 4.0 drops support for 80386 processors. Windows NT 4.0 allows installation without a floppy drive via CD-ROM media, although a floppy drive is required if one wants to make an Emergency Repair Disk or if not booting directly from the CD.
=== Hardware compatibility ===
Earlier releases of Windows NT 4.0 since build 1227 do not support processors with a CPUID higher than 3.CPU Identification by the 32-Bit Windows Kernel, Geoff Chappell - Software Analyst. 22 January 2008. The system will crash during setup or boot if running without limiting the CPUID to less than 3, and before Service Pack 4, processors with CMPXCHG8b supported which vendor ID not GenuineIntel, AuthenticAMD or CyrixInstead will also crash during booting.https://jeffpar.github.io/kbarchive/kb/189/Q189988/https://www.geoffchappell.com/studies/windows/km/cpu/cx8.htmService Pack 6 fully fixes this kernel issue.
== Product Team credits Easter egg ==
Windows NT 4.0 contains the Product Team credits Easter egg from Windows 95. Like in Windows 95, it is implemented in SHELL32.DLL, and the steps to show it are much the same as in Windows 95; create a new folder and renaming it to each of the following names in order:
* and now, the moment you've all been waiting for
* we proudly present for your viewing pleasure
* The Microsoft Windows NT Product Team!
The only main difference from the one in Windows 95 is that any references to "95" are replaced with "NT".
The text is in SHELL32.DLL's resource BIN and XORed with 0x95 as an obfuscation measure. For similar reasons, the Easter egg folder names are stored in the .text section of SHELL32.DLL as custom hashes of the old folder name concatenated with the new folder name. This was implemented by build 1175 and there shows the "SUR Shell Team" and "SUR Shell Test Team"; at some point after that the text was replaced by a message informing that "you won't find the credits here".
== Source code leak ==
In early 2004, the source code for Windows NT 4.0 Service Pack 2 leaked online, together with a partial copy of the Windows 2000 source code.https://archive.org/download/NFO_Collection_2000-2004_Compilation/NFO_COLLECTION_UNPACKED/2004/02-2004/NF_DAILY_NFO_COLLECTION-13-02-2004.zip/_NUKED_MICROSOFT.WINDOWS.2000.AND.NT4.SOURCE.CODE-SCENELEADER.nfo The source of the leak was traced to Mainsoft, the developer of MainWin, an application that allowed developers to port existing Windows programs to Unix systems, whose development required access to selected portions of Windows source code under Windows Interface Source Environment program.Mook, Nate. Windows Source Leak Traces Back to Mainsoft, BetaNews. 13 February 2004. In response, Microsoft released the following statement:
Despite the warnings, the archive containing the leaked code spread widely on the file-sharing networks and, even later, on open-source repository websites. On 16 February 2004, an exploit allegedly discovered by an individual studying the leaked source code for certain versions of Microsoft Internet Explorer was reported. On 15 April 2015, a repository containing the leaked NT 4.0 source code was removed from GitHub at Microsoft's request,Van der Sar, Ernesto. Microsoft Takes Pirated Windows NT 4.0 Source Code Offline, TorrentFreak. 15 April 2015. although other repositories hosting the Windows 2000 source code continued to exist in the same website; most of them were taken down by Microsoft's request on 9 April 2021.Microsoft. DMCA takedown request filed on behalf of Microsoft Corporation, GitHub. 9 April 2021.
== List of known builds ==
===Beta 1===
===Beta 2===
=== Release Candidate 1===
=== Release Candidate 2===
===Pre-RTM===
=== RTM===
=== International Beta ===
=== Service Pack 1 ===
=== Service Pack 2 ===
=== Service Pack 3 ===
=== Service Pack 4 ===
=== Service Pack 5 ===
=== Service Pack 6 ===
=== Service Pack 6a ===
=== Security Rollup ===
== Notes ==
== References ==
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