Windows NT 4.0 is a preemptive, graphical and business-oriented operating system designed to work with either uniprocessor or symmetric multi-processor computers. It was the next release of Microsoft's Windows NT line of operating systems and was released to manufacturing on 31 July 1996 . It is a 32-bit Windows system available in both workstation and server editions with a graphical environment similar to that of Windows 95. The "NT" designation in the product's title initially stood for "New Technology" according to Microsoft's then-CEO Bill Gates, but now no longer has any specific meaning. Windows NT 4.0 was succeeded by Windows 2000 in February 2000. Windows NT 4.0 is classified as a hybrid kernel operating system.
While providing much greater stability than Windows 95, it was also less flexible from a desktop perspective. Much of the stability is gained by the use of protected memory and the hardware abstraction layer. Direct hardware access was disallowed and "misbehaving" applications were terminated without needing the computer to be restarted. The trade-off was that NT required an excessive amount of memory in comparison to consumer targeted products such as Windows 95.
While nearly all programs written for Windows 95 will run on Windows NT, the majority of 3D games will not, due in part to NT 4.0 having limited support for DirectX. Third-party device drivers were an alternative that could to access the hardware directly, but poorly written drivers became a frequent source of "stop errors". Such failures began to be referred to as the "blue screen of death" or BSOD and would require the system to be restarted in such cases. These errors were rare and it was not uncommon for NT servers or workstations to run for months at a time without failure. By comparison Windows consumer versions at the time were much less stable and popularized the belief that all Windows versions were unreliable.
Windows NT 4.0 is also less user-friendly than Windows 95 when it comes to certain maintenance and management tasks; for instance, by default there is no Plug and Play support (although limited support could be installed later) which greatly simplifies installation of hardware devices. Many basic DOS applications would run, however graphical DOS applications would not run due to the way they accessed graphics hardware.
The difference between the NT and "9x" lines of Windows ended with the arrival of Windows XP, by which time the gaming APIs—such as OpenGL and DirectX—had matured sufficiently to be more efficient to write for than common PC hardware and the hardware itself had become powerful enough to handle the API processing overhead acceptably.
Windows NT 4.0 is the last major release of Microsoft Windows to support the Alpha, MIPS or PowerPC CPU architectures. It remained in use by businesses for a number of years, despite Microsoft's many efforts to get customers to upgrade to Windows 2000 and newer versions. It was also the last release in the Windows NT line to be branded as Windows NT.