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Windows NT

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Title: Windows NT  
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Windows NT

Windows NT
Developer Microsoft
Written in C, C++, and Assembly language[1]
Working state Current
Source model Closed source / Shared source
Initial release July 27, 1993 (1993-07-27) (as Windows NT 3.1)
Latest release 6.3.9600 (October 17, 2013 (2013-10-17)) [2]
Update method Windows Update, Windows Server Update Services
Platforms IA-32, x86-64, DEC Alpha, MIPS, PowerPC, ARM, Itanium
Kernel type Hybrid
Default user interface Graphical (Windows shell)
License Depending on version, edition or customer choice: Trialware, commercial software, volume licensing, OEM-only, SaaS, S+S[1]
Official website //

Windows NT is a family of operating systems produced by Microsoft, the first version of which was released in July 1993. It is a processor-independent, multiprocessing, multi-user operating system.

The first version of Windows NT was Windows NT 3.1 and was produced for workstations and server computers. It was intended to complement consumer versions of Windows (including Windows 1.0 through Windows 3.1x) that were based on MS-DOS. Gradually, Windows NT family was expanded into Microsoft's general-purpose operating system family for all personal computers, deprecating Windows 9x family.

"NT" was formerly expanded to "New Technology" but no longer carries any specific meaning. Starting with Windows 2000,[3] "NT" was removed from the product name and is only included in the product version string.[4]

NT was the first purely 32-bit version of Windows, whereas its consumer-oriented counterparts, Windows 3.1x and Windows 9x, were 16-bit/32-bit hybrids. It is a multi-architecture operating system: Initially, it supported several CPU architectures, including IA-32, MIPS, DEC Alpha and PowerPC. The latest versions support, x86 (more specifically IA-32 and x64), and ARM. Major features of Windows NT family include Windows Shell, Windows API, Native API, Active Directory, Group Policy, Hardware Abstraction Layer, NTFS file system, BitLocker, Windows Store, Windows Update, and Hyper-V.


  • Naming 1
  • Major features 2
  • Development 3
  • Driver models 4
  • Releases 5
  • Supported platforms 6
    • 32-bit platforms 6.1
    • 64-bit platforms 6.2
    • Hardware requirements 6.3
  • See also 7
  • Notes 8
  • References 9
  • External links 10


It has been suggested that Dave Cutler intended the initialism "WNT" as a pun on VMS, incrementing each letter by one.[5] However, the project was originally intended as a follow-on to OS/2 and was referred to as "NT OS/2" before receiving the Windows brand.[6] One of the original NT developers, Mark Lucovsky, states that the name was taken from the original target processor—the Intel i860, code-named N10 ("N-Ten").[7] Various Microsoft publications, including a 1998 question-and-answer session with Bill Gates, reveal that the letters were previously expanded to "New Technology" but no longer carry any specific meaning.[8] The letters were dropped from the name of Windows 2000, though Microsoft described the product as "Built on NT Technology".[3][9]

Major features

A main design goal of NT was hardware and software portability. Various versions of NT family operating systems have been released for a variety of processor architectures, initially IA-32, MIPS, and DEC Alpha, with PowerPC, Itanium, x86-64 and ARM supported in later releases. The idea was to have a common code base with a custom Hardware Abstraction Layer (HAL) for each platform. However, support for MIPS, Alpha, and PowerPC was later dropped in Windows 2000. Broad software compatibility was achieved with support for several API "personalities", including Windows API, POSIX,[10] and OS/2 APIs[11] – the latter two were phased out starting with Windows XP.[12] Partial MS-DOS compatibility was achieved via an integrated DOS Virtual Machine – although this feature is being phased out in the x86-64 architecture.[13] NT supported per-object (file, function, and role) access control lists allowing a rich set of security permissions to be applied to systems and services. NT supported Windows network protocols, inheriting the previous OS/2 LAN Manager networking, as well as TCP/IP networking (for which Microsoft would implement a TCP/IP stack derived at first from a STREAMS-based stack from Spider Systems, then later rewritten in-house).[14]

Windows NT 3.1 was the first version of Windows to use 32-bit flat virtual memory addressing on 32-bit processors. Its companion product, Windows 3.1, used segmented addressing and switches from 16-bit to 32-bit addressing in pages.

Windows NT 3.1 featured a core kernel providing a system API, running in supervisor mode (ring 0 in x86; referred to in Windows NT as "kernel mode" on all platforms), and a set of user-space environments with their own APIs which included the new Win32 environment, an OS/2 1.3 text-mode environment and a POSIX environment. The full preemptive multitasking kernel could interrupt running tasks to schedule other tasks, without relying on user programs to voluntarily give up control of the CPU, as in Windows 3.1 Windows applications (although MS-DOS applications were preemptively multitasked in Windows starting with Windows 1.0).

Notably, in Windows NT 3.x, several I/O driver subsystems, such as video and printing, were user-mode subsystems. In Windows NT 4, the video, server, and printer spooler subsystems were moved into kernel mode. Windows NT's first GUI was strongly influenced by (and programmatically compatible with) that from Windows 3.1; Windows NT 4's interface was redesigned to match that of the brand new Windows 95, moving from the Program Manager to the Windows shell design.

NTFS, a journaled, secure file system, was created for NT. Windows NT also allows for other installable file systems; starting with versions 3.1, NT could be installed on FAT or HPFS file systems.[15] Windows Vista and Windows 7 require a FAT32 partition to boot on an EFI based system.[16]


Microsoft decided to create a portable operating system, compatible with OS/2 and POSIX and supporting multiprocessing, in October 1988.[17] When development started in November 1989, Windows NT was to be known as OS/2 3.0,[18] the third version of the operating system developed jointly by Microsoft and IBM. To ensure portability, initial development was targeted at the Intel i860XR RISC processor, switching to the MIPS R3000 in late 1989, and then the Intel i386 in 1990.[19] Microsoft also continued parallel development of the DOS-based and less resource-demanding Windows environment, resulting in the release of Windows 3.0 in May 1990. Windows 3 was eventually so successful that Microsoft decided to change the primary application programming interface for the still unreleased NT OS/2 (as it was then known) from an extended OS/2 API to an extended Windows API. This decision caused tension between Microsoft and IBM and the collaboration ultimately fell apart. IBM continued OS/2 development alone while Microsoft continued work on the newly renamed Windows NT. Though neither operating system would immediately be as popular as Microsoft's MS-DOS or Windows products, Windows NT would eventually be far more successful than OS/2.

Microsoft hired a group of developers from Digital Equipment Corporation led by Dave Cutler to build Windows NT, and many elements of the design reflect earlier DEC experience with Cutler's VMS[20] and RSX-11. The operating system was designed to run on multiple instruction set architectures and multiple hardware platforms within each architecture. The platform dependencies are largely hidden from the rest of the system by a kernel mode module called the HAL (Hardware Abstraction Layer).

Windows NT's kernel mode code further distinguishes between the "kernel", whose primary purpose is to implement processor and architecture dependent functions, and the "executive". This was designed as a modified microkernel, as the Windows NT kernel was influenced by the Mach microkernel developed at Carnegie Mellon University,[21] but does not meet all of the criteria of a pure microkernel. Both the kernel and the executive are linked together into the single loaded module ntoskrnl.exe; from outside this module there is little distinction between the kernel and the executive. Routines from each are directly accessible, as for example from kernel-mode device drivers.

API sets in the Windows NT family are implemented as subsystems atop the publicly undocumented "native" API; this allowed the late adoption of the Windows API (into the Win32 subsystem). Windows NT was one of the earliest operating systems to use Unicode internally.

Driver models

Windows NT introduced its own driver model, the Windows NT driver model, and is incompatible with older driver frameworks. With Windows 2000, the Windows NT driver model was enhanced to become the Windows Driver Model, which was first introduced with Windows 98, but was based on the NT driver model.[22] Windows Vista added native support for the Windows Driver Foundation, which is also available for Windows XP, Windows Server 2003 and to an extent, Windows 2000.


Windows NT releases
Version Marketing name Editions Release date Build number
3.1 Windows NT 3.1 Workstation (named just Windows NT), Advanced Server July 27, 1993 528
3.5 Windows NT 3.5 Workstation, Server September 21, 1994 807
3.51 Windows NT 3.51 Workstation, Server May 30, 1995 1057
4.0 Windows NT 4.0 Workstation, Server, Server Enterprise Edition, Terminal Server, Embedded July 29, 1996 1381
5.0 Windows 2000 Professional, Server, Advanced Server February 17, 2000 2195
Datacenter Server September 26, 2000
5.1 Windows XP Home, Professional, Media Center (original, 2003, 2004 & 2005), Tablet PC (original and 2005), Starter, Embedded, Home N, Professional N October 25, 2001 2600
Windows Fundamentals for Legacy PCs N/A July 8, 2006
5.2 Windows XP 64-bit Edition Version 2003[23] March 28, 2003 3790
Windows Server 2003 Standard, Enterprise, Datacenter, Web, Storage, Small Business Server, Compute Cluster April 24, 2003
Windows XP Professional x64 Edition April 25, 2005
Windows Server 2003 R2 Standard, Enterprise, Datacenter, Web, Storage, Small Business Server, Compute Cluster December 6, 2005
Windows Home Server N/A July 16, 2007
6.0 Windows Vista Starter, Home Basic, Home Premium, Business, Enterprise, Ultimate, Home Basic N, Business N
  • Business: November 30, 2006
  • Consumer: January 30, 2007
  • 6000 (RTM)
  • 6001 (SP1)
  • 6002 (SP2)
Windows Server 2008 Foundation, Standard, Enterprise, Datacenter, Web Server, HPC Server, Itanium-Based Systems[24] February 27, 2008
  • 6001 (RTM)
  • 6002 (SP2)
6.1[25] Windows 7 Starter, Home Basic, Home Premium, Professional, Enterprise, Ultimate[26] October 22, 2009[27]
  • 7600 (RTM)
  • 7601 (SP1)
Windows Server 2008 R2 Foundation, Standard, Enterprise, Datacenter, Web Server, HPC Server, Itanium-Based Systems October 22, 2009[28]
  • 7600 (RTM)
  • 7601 (SP1)
Windows Home Server 2011 N/A April 6, 2011
  • 7600 (RTM)
6.2 Windows 8[29] Windows 8, Windows 8 Pro, Windows 8 Enterprise, Windows RT[30] October 26, 2012[31] 9200
Windows Server 2012[32] Foundation, Essentials, Standard, Datacenter[33] September 4, 2012 9200
6.3[34] Windows 8.1 Windows 8.1, Windows 8.1 Pro, Windows 8.1 Enterprise, Windows RT 8.1 October 18, 2013 9600[35]
Windows Server 2012 R2 Foundation, Essentials, Standard, Datacenter October 18, 2013 9600
10.0[36] Windows 10 TBA TBA TBA

Windows NT 3.1 to 3.51 incorporated the Program Manager and File Manager from the Windows 3.x series. Windows NT 4.0 onwards replaced those programs with Windows Explorer (including a taskbar and Start menu), which originally appeared in Windows 95.

The first release was given version number 3.1 to match the contemporary 16-bit Windows; magazines of that era claimed the number was also used to make that version seem more reliable than a ".0" release. Also apparently the Novell IPX protocol was apparently licensed only to 3.1 versions of Windows software.

The NT version number is not now generally used for marketing purposes, but is still used internally, and said to reflect the degree of changes to the core of the operating system;[37] however, for application compatibility reasons, Microsoft has kept the major version number as 6 in releases following Vista.[38] The build number is an internal identifier used by Microsoft's developers and beta testers.

Supported platforms

NT was written in C and C++,[39] and is reasonably portable, although (as of 2009) only three architectures are currently supported. That said, it proved far more difficult to port applications such as Microsoft Office which were sensitive to issues such as data structure alignment on RISC processors. Unlike Windows CE which routinely runs on a variety of processors, the lack of success of RISC-based systems in the desktop market has resulted in nearly all NT deployments being on x86 architecture processors.

32-bit platforms

In order to prevent Intel x86-specific code from slipping into the operating system by developers used to developing on x86 chips, Windows NT 3.1 was initially developed using non-x86 development systems and then ported to the x86 architecture. This work was initially based on the Intel i860-based Dazzle system and, later, the MIPS R4000-based Jazz platform. Both systems were designed internally at Microsoft.[40]

Windows NT 3.1 was released for Intel x86 PC compatible, DEC Alpha, and ARC-compliant MIPS platforms. Windows NT 3.51 added support for the PowerPC processor in 1995, specifically PReP-compliant systems such as the IBM Power Series desktops/laptops and Motorola PowerStack series; but despite meetings between Michael Spindler and Bill Gates, not on the Power Macintosh as the PReP compliant Power Macintosh project failed to ship.

Intergraph Corporation ported Windows NT to its Clipper architecture and later announced intention to port Windows NT 3.51 to Sun Microsystems' SPARC architecture,[41] but neither version was sold to the public as a retail product.

Only two of the Windows NT 4.0 variants (IA-32 and Alpha) have a full set of service packs available. All of the other ports done by third parties (Motorola, Intergraph, etc.) have few, if any, publicly available updates.

Windows NT 4.0 was the last major release to support Alpha, MIPS, or PowerPC, though development of Windows 2000 for Alpha continued until August 1999, when Compaq stopped support for Windows NT on that architecture; and then three days later Microsoft also canceled their AlphaNT program, even though the Alpha NT 5 (Windows 2000) release had reached RC2 (build 2128).[42]

Microsoft announced on 5 January 2011 that the next major version of the Windows NT family will include support for the ARM architecture. Microsoft demonstrated a preliminary version of Windows (version 6.2.7867) running on an ARM-based computer at the 2011 Consumer Electronics Show.[43] This eventually led to the commercial release of Windows RT on October 26, 2012.

According to Microsoft, it is a common misconception that the Xbox and Xbox 360 use a modified Windows 2000 kernel.[44] They claim that the Xbox operating system was built from scratch but implements a subset of Windows APIs. The idea that it does, indeed, run a modified copy of the Windows kernel still persists in the community.

64-bit platforms

DEC Alpha versions of Windows NT are 32-bit only. The 64-bit versions of Windows NT were originally intended to run on Itanium and DEC Alpha; the latter was used internally at Microsoft during early development of 64-bit Windows.[45][46] This continued for some time after Microsoft publicly announced that it was cancelling plans to ship 64-bit Windows for Alpha.[47]

While Windows 2000 only supports Intel IA-32 (32-bit), Windows XP, Server 2003, Server 2008 and Server 2008 R2 each have one edition dedicated to Itanium-based systems.[48][49][50] In comparison with Itanium, Microsoft adopted x64 on greater scales: Not only Windows XP has a dedicated x64 edition,[51] starting with Windows Server 2003, mainstream editions of every version of Windows support x64.[48][52]

Hardware requirements

The minimum hardware specification required to run each release of the professional workstation version of Windows NT has been fairly slow-moving until the 6.0 Vista release, which requires a minimum of 15 GB of free disk space, a 10-fold increase in free disk space alone over the previous version.

Windows NT minimum hardware requirements
NT version CPU RAM Free disk space
NT 3.1
NT 3.1 Advanced Server
386, 25 MHz 12 MB
16 MB
90 MB
NT 3.5 Workstation
NT 3.5 Server
386, 25 MHz 12 MB
16 MB
90 MB[53]
NT 3.51 Workstation
NT 3.51 Server
386, 25 MHz 12 MB
16 MB
90 MB[53]
NT 4.0 Workstation
NT 4.0 Server
486, 25 MHz 12 MB
16 MB
124 MB[54]
2000 Professional
2000 Server
Pentium, 133 MHz 32 MB
128 MB
650 MB[55]
XP Pentium, 233 MHz 64 MB 1.5 GB[56]
Server 2003 133 MHz 128 MB 1.5 GB[57]
Vista 800 MHz 512 MB 15 GB[58]
7 1 GHz 1GB 16 GB[59]
8 and 8.1 1 GHz with NX bit, SSE2, PAE 1GB 16 GB[60]
10 1 GHz 1GB 16 GB

See also



  1. ^ Lextrait, Vincent (January 2010). "The Programming Languages Beacon" (v10.0 ed.). Retrieved January 4, 2010. 
  2. ^ Popa, Bogdan (24 August 2013). "Windows 8.1 Build 9600 Compiled, RTM Still on Its Way".  
  3. ^ a b "Microsoft Renames Windows NT 5.0 Product Line to Windows 2000; Signals Evolution of Windows NT Technology Into Mainstream" (Press release).  
  4. ^ "OperatingSystem.VersionString Property".  
  5. ^ Zachary, G Pascal (1994). Show Stopper!: The Breakneck Race to Create Windows NT and the Next Generation at Microsoft. Free Press.  
  6. ^ "Microsoft Windows NT OS/2 Design Workbook". American history. Smithsonian. Retrieved 2008-11-15. 
  7. ^ Thurrott, Paul. "History of Windows Server 2003: The Road To Gold". Win super site. 
  8. ^ Gates, Bill (1998-06-05). "Q&A: Protecting children from information on the Internet". Archived from the original on 2001-05-26. Retrieved 2005-06-26. 
  9. ^ "Windows 2000 is a name that reflects NT's continued move to the technology mainstream". October 27, 1998. Retrieved November 13, 2011. 
  10. ^ "Paul Thurrott's SuperSite for Windows". Win super site. Retrieved 2010-11-24. 
  11. ^ "28 – OS/2 Compatibility", MS Windows NT 4 Workstation (resource kit), Microsoft, retrieved 2010-11-24 
  12. ^ "POSIX and OS/2 are not supported in Windows XP or in Windows Server 2003". Support. Microsoft. 2007-11-05. Retrieved 2010-11-24. 
  13. ^ "x64 editions deployment". Retrieved 2010-11-24. 
  14. ^ Barr, Adam (June 19, 2001), "Microsoft, TCP/IP, Open Source, and Licensing", , retrieved February 22, 2013  .
  15. ^ "File Systems". TechNet. Microsoft. Retrieved 2010-11-24. 
  16. ^ "UEFI Support and Requirements for Windows Operating Systems". Windows hardware developer conference. Microsoft. 2009-05-13. Retrieved 2010-11-24. 
  17. ^  .
  18. ^ Pollack, Andrew (1991-07-27), "Microsoft Widens Its Split With IBM Over Software", The  
  19. ^ Thurrott, Paul (2003-01-24). "Windows Server 2003: The Road To Gold". Win super site. Retrieved 2010-01-05. 
  20. ^ Russinovich, Mark (1 December 1998). "Windows NT and VMS: The Rest of the Story". Windows 2000. Windows IT pro. Retrieved 5 May 2012. 
  21. ^ "Supporting Windows NT and 2000 Workstation and Server". Technology network. Prentice Hall. 1999-12-01.  
  22. ^ "NT Drivers" (FAQ). CMKrnl. 
  23. ^ "Microsoft Releases Windows XP 64-Bit Edition Version 2003 to Manufacturing". March 2003. Retrieved 2008-01-14. 
  24. ^ "Overview of Editions". Windows Server 2008. Microsoft. Retrieved 2009-05-18. 
  25. ^ "Operating System Versioning".  
  26. ^ LeBlanc, Brandon (2009-02-04). "A closer look at the Windows 7 SKUs". Blogging Windows. Microsoft. Retrieved 2009-02-05. 
  27. ^ Rothman, Wilson (2009-06-02). "Windows 7 To Be Released October 22".  
  28. ^ "Product Roadmap". Windows Server 2008. Microsoft. Retrieved 2009-05-18. 
  29. ^ "Windows", Developer network, Microsoft 
  30. ^ LeBlanc, Brandon (2012-04-16). "Announcing the Windows 8 Editions". Blogging Windows. Microsoft. Retrieved 2012-04-17. 
  31. ^ "Windows 8 will be available on…". Microsoft. July 18, 2012. Retrieved July 18, 2012. 
  32. ^ "Windows server 8 named Windows server 2012", Windows valley .
  33. ^ "Windows Server 2012 Editions". Server cloud. Retrieved 2012-07-08. 
  34. ^ "Microsoft's Windows Blue looks to be named Windows 8.1",  
  35. ^ Warren, Tom (24 August 2013). "Windows 8.1 is ready for its October 17th release".  
  36. ^ Thurrott, Paul (22 November 2014). "Microsoft Confirms that Windows 10 will also be Version 10 Internally". SuperSite for Windows.  
  37. ^ Russinovich, Mark; Solomon, David (2001-12), "Developer network", MSDN mag (Microsoft), archived from the original on 2003-04-23, retrieved 2006-12-19 
  38. ^ "Why 7?". Windows Team Blog. Microsoft. 2008-10-14. Retrieved 2012-03-30. 
  39. ^ "Windows NT System Overview". Microsoft. Retrieved 2010-11-24. 
  40. ^ Lucovsky, Mark (2000-08-09). "Windows: A Software Engineering Odyssey". Retrieved 2006-11-02. 
  41. ^ "Intergraph Announces Port of Windows NT to SPARC Architecture". The Florida SunFlash. 1993-07-07. 
  42. ^ Nicholas Petreley (September 3, 1999). "Can Linux break Intel's hold on the market?".  
  43. ^ "Microsoft demonstrates early build of Windows 8", Win rumors .
  44. ^ Gandhi, Shaheen. "Xbox Team: The Xbox Operating System". Retrieved 2008-05-29. 
  45. ^ Thurott, Paul (December 1999). "The Road to Gold: The development of Windows 2000 Reviewed". Win super site. Retrieved 2008-01-05. 
  46. ^ Chen, Raymond (August 2008). "Windows Confidential". Technology network. Microsoft. 
  47. ^ Thurott, Paul (June 2000). "Windows 2000 Reportedly Returning to Alpha Platform". Windows IT pro. Retrieved 2008-01-05. UPDATE: Compaq has apparently denied that any work is being done on Windows 2000/64 for the Alpha. 
  48. ^ a b "Comparison of Windows Server 2003 Editions".  
  49. ^ "Windows Server 2008 for Itanium-Based Systems Feature Support". Microsoft TechNet. Microsoft. Retrieved 14 October 2011. 
  50. ^ "Windows Server 2008 R2 for Itanium-Based Systems". Windows Server Editions. Microsoft. Retrieved 14 October 2011. 
  51. ^ "Microsoft Windows XP 64-Bit Edition".  
  52. ^ "A description of the x64-based versions of Windows Server 2003 and of Windows XP Professional x64 Edition". Microsoft Support Center. Microsoft. Retrieved 14 October 2011. 
  53. ^ a b "Windows NT 3.5x Setup Troubleshooting Guide (MSKB 139733)". Microsoft. 2006-11-01. Retrieved 2010-11-24. 
  54. ^ "Info: Windows NT 4.0 Setup Troubleshooting Guide". Microsoft. 2006-10-31. Retrieved 2010-11-24. 
  55. ^ "System requirements for Microsoft Windows 2000 operating systems". Microsoft. 2007-11-13. Retrieved 2010-11-24. 
  56. ^ "System requirements for Microsoft Windows XP operating systems". Microsoft. 2007-09-14. Retrieved 2010-11-24. 
  57. ^ "Windows Server 2003, Standard Edition: System requirements". Microsoft. 2005-01-21. Retrieved 2013-01-11. 
  58. ^ "System requirements for Microsoft Windows Vista". Microsoft. 2007-11-13. Retrieved 2010-11-24. 
  59. ^ "Windows 7 system requirements". Microsoft. Retrieved 2009-08-30. 
  60. ^ "Windows 8 system requirements". Microsoft. Retrieved 2012-10-29. 

External links

  • Windows (official page), Microsoft .
  • Russinovich, Mark, "Windows NT and VMS: The Rest of the Story", Win 2000 (discussion of ancestry of NT), archived from the original on 2002-05-03 .
  • A Brief History of the Windows NT Operating System (fact sheet), Microsoft PressPass, 1998, archived from the original on 2004-06-10 .
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