Windows NT 4.0

Windows NT 4.0 (codenamed Shell Update Release) is a major release of Windows NT, the successor to Windows NT 3.51, released a year prior, and the first version of Windows NT to feature the Windows Explorer interface introduced in Windows 95. It is the second version of Windows NT to support upgrade paths to Windows 2000, as well as the first version of Windows NT to support upgrade paths to Windows XP or Windows Server 2003, and thus the last version of Windows NT to include NT in its product name and also the last version to support upgrade paths from Windows NT 3.1 and Windows NT 3.5. It is also the final version of Windows which supports the Alpha, MIPS, and PowerPC architectures; its successor, Windows 2000 does not support these architectures.

The Windows Desktop Update further enhances the shell by incorporating features from Windows 98, which requires installing Internet Explorer 4. Internet Explorer versions, Internet Explorer 2 through Internet Explorer 6 were available for Windows NT 4.0. Web browsers for Windows NT 4.0 based on and including Mozilla Firefox were operable up to version 2.0.0.22, released in April 2009, as later versions of Firefox would require Windows 98 with KernelEx installed.

Editions
There are several editions of Windows NT 4.0:


 * Workstation
 * Server
 * Server, Enterprise Edition
 * Server, 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. There was a 7th Service Pack planned, but it was canceled and an Update Rollup was released instead in 2001.

Option Pack
Microsoft released an option pack for Windows NT 4.0 in 1997. It 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 and Data Access Components. Unlike the Service Packs, it is not mandatory, but it requires Windows NT 4.0 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 to continue. This is the only option pack to be released, as most of the components became part of Windows 2000.

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. Windows NT 4.0 drops support for 80386 processors. Windows NT 4.0 allows installation to be possible 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 versions of Windows NT 4.0 does not support processors with a CPUID higher than 3. Windows NT 4.0 will crash during setup or boot if run without limiting the CPUID to less than 3. Service Pack 6 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, 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 's resource   and XORed with   as an obfuscation measure. For similar reasons, the Easter egg folder names are stored in the  section of   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
On 12 February 2004, over 30000 source files, partly for Windows NT 4.0, were leaked onto the internet. This would later be pinpointed to Mainsoft.