Editing Windows NT 3.1

{{Short description|First major release of Windows NT}}
{{About|the major release of Windows NT|the consumer operating system|Windows 3.1}}
{{use mdy dates|date=May 2022}}
{{Infobox OS
| version of = [[Windows NT]]
| name = Windows NT 3.1
| logo = Microsoft Windows NT 3.1 logo with wordmark.svg
| logo_alt = Logo of Windows NT 3.1
| logo size = x100px
| screenshot = Windows NT 3.1.png
| caption = Screenshot of Windows NT 3.1
| developer = [[Microsoft]]
| family = [[Microsoft Windows]]
| source_model = [[Closed-source]]
| first release date = {{start date and age|1993|7|27}}<ref>{{cite web|url=http://blogs.technet.com/b/mrsnrub/archive/2009/08/04/windows-nt-history.aspx|title=Windows NT History|author1=Paul Adams|date=August 4, 2009}}</ref>
| latest release date = {{start date and age|1994|10|29}}
| latest release version = Service Pack 3 (3.1.528)
| supported_platforms = [[IA-32]], [[DEC Alpha|Alpha]], [[MIPS architecture|MIPS]]
| kernel_type = [[Hybrid kernel|Hybrid]] ([[Windows NT kernel|NT]])
| userland = {{ubl|[[Windows API]]|[[NTVDM]]|[[Microsoft OS/2 subsystem|OS/2 1.x]]|[[Microsoft POSIX subsystem|POSIX.1]]}}
| license = [[Commercial software]]
| preceded by = [[Windows 3.1]] (1992)
| succeeded by = [[Windows NT 3.5]] (1994)
| support_status = Unsupported as of December 31, 2000<ref>{{cite web|archive-url= https://web.archive.org/web/20040611115848/http://support.microsoft.com/default.aspx?scid=fh;%5bln%5d;LifeWin|url= http://support.microsoft.com/default.aspx?scid=fh;%5bln%5d;LifeWin|website=Microsoft|access-date=2021-08-24|archive-date=2004-06-11|title=Product Lifecycle Dates - Windows Product Family}}</ref>
}}
'''Windows NT 3.1''' is the first major release of the [[Windows NT]] [[operating system]] developed by [[Microsoft]], released on July 27, 1993. It marked the company's entry into the corporate computing environment, designed to support large [[Computer network|networks]] and to be portable, compiled for [[X86|Intel x86]], [[DEC Alpha]] and [[MIPS architecture|MIPS]] based [[workstation]]s and [[Server (computing)|servers]].<ref name=":1">{{cite web |date=May 24, 1993 |title=Microsoft Soft-Pedaling Its Latest |url=https://www.nytimes.com/1993/05/24/business/microsoft-soft-pedaling-its-latest.html |website=[[The New York Times]]}}</ref> It was Microsoft's first [[32-bit computing|32-bit]] operating system, providing advantages over the constrictive [[16-bit architecture]] of previous versions of Windows that relied on [[DOS]], but retaining a [[desktop environment]] familiar to [[Windows 3.1]] users.<ref name=":1" />

Windows NT began as a rewrite of the [[OS/2]] operating system, which Microsoft had co-developed with [[IBM]] but failed to gain much traction against [[Unix]], with vendor [[Sun Microsystems]] dominating the market for powerful desktop workstations.<ref>{{Cite web |date=May 5, 1993 |title=Sun launches technology to run Windows programs - UPI Archives |url=https://www.upi.com/Archives/1993/05/05/Sun-launches-technology-to-run-Windows-programs/1826736574400/ |access-date=2024-12-04 |website=[[UPI]] |language=en}}</ref> For several reasons, including the market success of [[Windows 3.0]] in 1990, Microsoft decided to advance Windows rather than OS/2 and relinquished their OS/2 development responsibilities. By [[Brand extension|extending]] the Windows brand and beginning NT at [[Software versioning|version]] 3.1, like Windows 3.1 which had established [[brand recognition]] and [[market share]], Microsoft implied that consumers should expect a familiar [[user experience]]. The name ''Windows NT'' ("New Technology") advertised that this was a re-engineered version of Windows.

First publicly demonstrated at [[COMDEX|Comdex]] 1991, NT 3.1 was released in 1993 in two editions: Workstation and Advanced Server. When Windows NT premiered, their sales were limited by high [[#System requirements|system requirements]], and a general lack of 32-bit [[Application software|applications]] to take advantage of the OS's data processing capabilities. It sold about 300,000 copies before it was succeeded by [[Windows NT 3.5]] in 1994. On December 31, 2000, Microsoft declared Windows NT 3.1 obsolete and stopped providing support and updates for the system.

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.

== Development history ==
The origins of Windows NT date back to 1988,<ref name=":0">{{Cite book |last=Cusumano |first=Michael A. |url=https://www.worldcat.org/oclc/40671451 |title=Microsoft secrets: how the world's most powerful software company creates technology, shapes markets, and manages people |date=1998 |publisher=Simon & Schuster |others=Richard W. Selby |isbn=0-684-85531-3 |edition=1 |location=New York |pages=144 |oclc=40671451}}</ref> where Microsoft had a major foothold on the [[personal computer]] market due to the use of its [[MS-DOS]] as the operating system of [[IBM PC compatible]]s. [[Nathan Myhrvold]], who had joined Microsoft after its acquisition of Dynamical Systems Research, identified two major threats to Microsoft's monopoly—[[Reduced instruction set computing|RISC]] architectures, which proved to be more powerful than the equivalent [[Intel]] processors that MS-DOS ran on, and [[Unix]], a family of [[cross-platform]] [[Computer multitasking|multitasking]] operating systems with support for [[multiprocessing]] and [[Computer network|networking]].<ref name="ZacharyShowstopper" />{{rp|page=34}} While the widespread use of Unix was hindered by the need to adapt programs for each individual variant, [[Bill Gates]] believed that the combination of a Unix-like operating system with RISC processors could be a market threat, prompting the need for Microsoft to develop a "Unix killer" that could run on multiple architectures.<ref name="ZacharyShowstopper">{{cite book | last= Zachary | first= G. Pascal | title= Showstopper!: The breakneck race to create Windows NT and the next generation at Microsoft | publisher= E-Rights/E-Reads | location= New York | year= 2009 | isbn=978-0-7592-8578-1}}</ref>{{rp|page=35}} Myhrvold wanted to develop a new system that would run on RISC workstations and [[Intel]] [[Computer chip|chips]] and [[multiprocessing]] computers.<ref name=":0" /> Gates had also hired [[Dave Cutler]] from [[Digital Equipment Corporation]] to assist in developing the new operating system; Cutler left DEC after the cancellation of the [[DEC PRISM|PRISM]] architecture and its [[DEC MICA|MICA]] operating system, and agreed to join Microsoft on the condition that he be able to bring a number of staff members from his team at DEC with him.<ref name=":0" /><ref name="ZacharyShowstopper" />{{rp|pages=17–37}} Cutler arrived at Microsoft in October 1988, and began working on the development of the operating system in November.<ref name="ZacharyShowstopper" />{{rp|page=38}}<ref name="smith">{{cite web |last=Smith |first=Mark |date=August 26, 1999 |title=The Death of Alpha on NT |url=https://www.itprotoday.com/compute-engines/death-alpha-nt |access-date=2012-05-19 |website=ITPro Today}}</ref>

The operating system was first developed as a revised version of [[OS/2]], an operating system Microsoft had jointly developed with [[IBM]].<ref name="Custer1993"/>{{rp|pages=43–44}} While OS/2 was originally intended to succeed MS-DOS, it had yet to be commercially successful. The OS was to be designed so it could be [[porting|ported]] to different processor platforms, and support multiprocessor systems, which few operating systems did at that time.<ref name="ZacharyShowstopper" />{{rp|page=33}}<ref name="Custer1993">{{cite book | last= Custer | first= Helen | title= Inside Windows NT | publisher= Microsoft Press | location= Redmond | year= 1993 | isbn= 1-55615-481-X | url-access= registration | url= https://archive.org/details/insidewindowsnt00cust}}</ref>{{rp|page=2}}<ref name="handbook">{{cite web |date=February 7, 2012 |title=Microsoft Windows NT OS/2 Design Workbook |url=https://americanhistory.si.edu/collections/search/object/nmah_742559 |access-date=2012-06-09 |website=National Museum of American History}}</ref> To target the enterprise market, the OS was also to support networking, the [[POSIX]] standard, and a security platform compliant with the "[[Trusted Computer System Evaluation Criteria|Orange Book]]" standards; which would require the OS to be a [[multi-user]] system with a permission framework and the ability to audit security-related events.<ref name="usdod">{{cite web |date=December 26, 1985 |title=Department of Defense – Trusted Computer System Evaluation Criteria |url=http://csrc.nist.gov/publications/history/dod85.pdf |access-date=2012-09-19 |format=PDF; 0,4 MB}}</ref>

Both Microsoft and IBM wanted to market an operating system that appealed to corporate "[[enterprise software]]" customers. That meant greater [[Computer security|security]], [[Reliability engineering|reliability]], processing power, and [[computer networking]] features. However, since Microsoft also wanted to capture market share from Unix on other [[computing platforms]], they needed a [[Systems design|system design]] that was more [[Software portability|portable]] than that of OS/2.

To this end, Microsoft began by developing and testing their new operating system for a non-[[x86]] processor: an [[Emulator|emulated]] version of the [[Intel i860]]. Alluding to the chip's codename, "N10", Microsoft codenamed their operating system '''NT OS/2'''.<ref name="thurrott">{{cite web |last=Thurrott |first=Paul |date=2003-01-24 |title=Windows Server 2003: The Road To Gold - Part One: The Early Years |url=http://www.winsupersite.com/reviews/winserver2k3_gold1.asp |archive-url=https://web.archive.org/web/20050101005634/http://www.winsupersite.com/reviews/winserver2k3_gold1.asp |archive-date=2005-01-01 |access-date=2012-05-28 |website=Windows SuperSite}}</ref> DEC preemptively sued Microsoft, alleging that they stole code from MICA for use in the new operating system. In an out-of-court settlement, Microsoft agreed to make NT OS/2 compatible with DEC's [[DEC Alpha|Alpha processor]].<ref name="smith" />

The development team originally estimated that development would be complete within 18 months. By April 1989, the NT OS/2 kernel could run inside the i860 emulator. However, the development team later determined that the i860 was unsuitable for the project. By December they had begun porting NT OS/2 to the [[MIPS architecture|MIPS]] [[R3000]] processor instead, and completed the task in three months.<ref name="thurrott" /> Senior Microsoft executive [[Paul Maritz]] was targeting a release date in 1992, but the development schedule was uncertain. The company was eager to silence naysayers who speculated that NT wouldn't be on the market until 1994, and had planned to present the new OS at [[COMDEX]] in 1990.<ref name="Custer1993"/>{{rp|pages=84–85}}

=== As Windows NT ===
In May 1990, Microsoft released [[Windows 3.0]], a new version of its MS-DOS-based [[Microsoft Windows|Windows]] [[desktop environment]]. Windows 3.0 sold well, and the resulting shift in Microsoft's marketing strategy eroded their partnership with IBM—who wanted Microsoft to concentrate solely on developing OS/2 as its primary platform as opposed to building their future business around Windows.<ref name="ZacharyShowstopper"/>{{rp|page=100}} Users and developers were unsure of whether to adopt Windows or OS/2 due to these uncertainties (a situation magnified by the fact that the operating systems were incompatible with each other at the [[Application programming interface|API]] level), while Microsoft's resources were also being drained by the simultaneous development of multiple operating systems.<ref name="Custer1993"/>{{rp|pages=98–99}}<ref name="IW27May1991_S66">{{cite journal | last=Glass | first=Brett | title=Windows, OS/2 debate is still a hot topic: Software vendors with limited resources are still forced to choose between Windows and OS/2 development | journal=InfoWorld | volume=13 | issue=21 | date=1991-05-27 | pages=66 | url= https://books.google.com/books?id=YlAEAAAAMBAJ&pg=PA66}}</ref> In August 1990, as a response to the popularity of Windows 3.0, the NT OS/2 team decided to re-work the operating system to use an extended [[32-bit]] port of the [[Windows API]] known as Win32. Win32 maintained the familiar structure of the [[16-bit]] APIs used by Windows, which would allow developers to easily adapt their software for the new platform while maintaining a level of compatibility with existing software for Windows.<ref name="IW8Jul1991_S1_103">{{cite journal | last=Johnston | first=Stuart J. | title=Microsoft drops OS/2 2.0 API, revamps 32-bit Windows plan: Users face choice between OS/2 and Windows NT | journal=InfoWorld | volume=13 | issue=27 | date=1991-07-08 | pages=1, 103 | url= https://books.google.com/books?id=iVAEAAAAMBAJ&pg=PA1}}</ref> With the shift to a Windows-like architecture, the operating system's [[Shell (computing)|shell]] was also changed from OS/2's [[Presentation Manager]] to Windows' [[Program Manager]].<ref name="ZacharyShowstopper"/>{{rp|pages=102–105}}

Due to these changes, NT was not presented at COMDEX 1990 as was originally planned.<ref name="ZacharyShowstopper"/>{{rp|page=102}} Neither the general public nor IBM knew about the transformation of NT OS/2 into ''Windows NT'' at the time.<ref name="ZacharyShowstopper"/>{{rp|page=108}} Although the companies did agree to a revised partnership where IBM and Microsoft would alternate developing major versions of OS/2 instead of collaborating on each version,<ref name="IW24Dec1990_S8">{{cite journal | last=Parker | first=Rachel | title=Two giants with own views: IBM needs OS/2; Microsoft does Windows| journal=InfoWorld | volume=12 | issue=52 | date=1990-12-24 | pages=8 | url= https://books.google.com/books?id=sFAEAAAAMBAJ&pg=PA8}}</ref> IBM eventually learned of Microsoft's Windows NT plans in January 1991, and immediately ended the OS/2 partnership. IBM would solely develop OS/2 2.0 (as was planned under the amended version) and all future versions, without any further involvement from Microsoft.<ref name="Custer1993" />{{rp|pages=108–109}}<ref name="IW8Jul1991_S1_103" />

In October 1991, Windows NT received its first public demonstration at COMDEX. In an effort to ensure software taking advantage of Windows NT was available upon its release (scheduled for late-1992), Microsoft also distributed a 32-bit [[software development kit]] to selected developers in attendance.<ref name="ZacharyShowstopper"/>{{rp|page=165}}<ref name="IW28Oct1991_S1_8">{{cite journal | last=Johnston | first=Stuart J. | title=NT looks real at Comdex: Microsoft declares it will start beta tests in early 1992 | journal=InfoWorld | volume=13 | issue=43 | date=1991-10-28 | pages=1, 8 | url= https://books.google.com/books?id=dT0EAAAAMBAJ&pg=PA1}}</ref> The demonstration was positively received; [[PC Magazine]] called Windows NT "the modern reinvention of the operating system", but at the same time claimed that it was unlikely that the promised [[backward compatibility]] would be kept for the final release.<ref name="Custer1993" />{{rp|pages=175–176}}<ref name="PCMag26Nov1991_S8586">{{cite journal| last=Machrone | first=Bill | title=Are NT Promises MT Promises? | journal=PC Magazine | volume=10 | issue=20 | date=1991-11-26 | pages=85f |issn=0888-8507 | url= https://books.google.com/books?id=wEufoGXlUxUC}}</ref> In March 1992, Microsoft also released [[Win32s]], which would allow [[Windows 3.1]] to have partial compatibility with Windows NT programs for the purposes of developing software optimized for the platform.<ref name="IW2Mar1992_S1_107">{{cite journal | last=Johnston | first=Stuart J. | title=Microsoft reveals 32-bit strategy: Win32s lets NT applications run on Windows 3.1 | journal=InfoWorld | volume=14 | issue=9 | date=1992-03-02 | pages=1, 107 | url= https://books.google.com/books?id=9z0EAAAAMBAJ&pg=PA1}}</ref>

At Microsoft's [[Professional Developers Conference|Win32 Professional Developers Conference]] in June 1992, Windows NT was demonstrated running on x86 and MIPS processors, while a beta version of Windows NT and an updated development kit were also made available.<ref name="IW13Jul1992_S1_92">{{cite journal | last=Strehlo | first=Kevin | title=Microsoft makes its move with Windows NT SDK | journal=InfoWorld | volume=14 | issue=28 | date=1992-07-13 | pages=1, 92 | url= https://books.google.com/books?id=elEEAAAAMBAJ&pg=PA1}}</ref> Concurrently, Microsoft announced a new version of its [[Microsoft SQL Server|SQL Server]] product for Windows NT; Unix vendors feared that the software could be a [[killer app]] that would affect the market share of Unix systems.<ref name="IW20Jul1992_S8">{{cite journal | last=Johnston | first=Stuart J. | title=SDK readied for SQL Server for NT: Will speed writing of 32-bit code | journal=InfoWorld | volume=14 | issue=29 | date=1992-07-20 | pages=8 | url= https://books.google.com/books?id=IlEEAAAAMBAJ&pg=PA8}}</ref><ref name="IW14Dec1992_S8">{{cite journal | last1=Hammett | first1=Jim | last2=McCarthy | first2=Vance | title=Unix vendors strike out at Microsoft: Campaign seeks to steal thunder of Windows NT | journal=InfoWorld | volume=14 | issue=50 | date=1992-12-14 | pages=8 | url= https://books.google.com/books?id=S1EEAAAAMBAJ&pg=PA8}}</ref> Concerns were also raised over NT's memory usage; while most computers of the era shipped with 4 megabytes of [[Random-access memory|RAM]], 16 MB was recommended for NTs. Due to the high cost of RAM at the time, critics thought that its high system requirements could affect the sales and adoption of Windows NT. Steps were taken to reduce its memory usage through methods such as [[paging]].<ref name="Custer1993"/>{{rp|page=227–249}}

Microsoft began releasing public beta builds of NT in October 1992, and a month later at COMDEX, a presentation focusing on third-party software for Windows NT was held.<ref name="IW12Oct1992_S17">{{cite journal | last=Willett | first=Shawn | title=NT's delays mean a second look and respect for OS/2 | journal=InfoWorld | volume=14 | issue=41 | date=1992-10-12 | pages=17 | url= https://books.google.com/books?id=n1EEAAAAMBAJ&pg=PA17}}</ref><ref name="IW26Oct1992_S3">{{cite journal | last=Johnston | first=Stuart J. | title=Microsoft rolls out Windows NT beta | journal=InfoWorld | volume=14 | issue=43 | date=1992-10-26 | pages=3 | url= https://books.google.com/books?id=hFEEAAAAMBAJ&pg=PA3}}</ref><ref name="IW23Nov1992_S3">{{cite journal | last=Johnston | first=Stuart J. | title=Vendors throw support behind Windows NT | journal=InfoWorld | volume=14 | issue=47 | date=1992-11-23 | pages=3 | url= https://books.google.com/books?id=LlEEAAAAMBAJ&pg=PA3}}</ref> The final pre-release version of NT was released in March 1993, alongside the unveiling of the server version, ''LAN Manager for Windows NT''. Although its stability and performance had improved, there were still fears that the OS could be released in an unfinished state or delayed further into 1993.<ref name="IW5Apr1993_S3">{{cite journal | last=Johnston | first=Stuart J. | title=NT is shaping up, say latest beta users: But they want a bug-free final version, even if it's late | journal=InfoWorld | volume=15 | issue=14 | date=1993-04-05 | pages=3 | url= https://books.google.com/books?id=ODwEAAAAMBAJ&pg=PA3}}</ref><ref name="IW31May1993_S13">{{cite journal | last1=Willett | first1=Shawn | last2=Borzo | first2=Jeanette | title=Users praise NT's graphics support at Comdex | journal=InfoWorld | volume=15 | issue=22 | date=1993-05-31 | pages=13 | url= https://books.google.com/books?id=PDsEAAAAMBAJ&pg=PA13}}</ref>

By [[Brand extension|extending]] the Windows brand and beginning NT at [[Software versioning|version]] 3.1, like [[Windows 3.1]] which had established [[brand recognition]] and [[market share]], Microsoft implied that consumers should expect a familiar [[user experience]] yet re-engineered.

=== Release ===
Windows NT 3.1 and Windows NT 3.1 Advanced Server (so numbered to associate them with [[Windows 3.1]]) were released on July 26, 1993.<ref name="ZacharyShowstopper"/>{{rp|page=300}} At first, only the x86 and MIPS versions shipped; the DEC Alpha version followed in September.<ref name="thurrott" /><ref name="IW20Sep1993_S3">{{cite journal | last1=Johnston | first1=Stuart J. | last2=Barney | first2=Doug | title=NT version for Alpha chip poised to ship to users | journal=InfoWorld | volume=15 | issue=38 | date=1993-09-20 | pages=3 | url= https://books.google.com/books?id=8zoEAAAAMBAJ&pg=PA3}}</ref> Microsoft sold the workstation version for {{US$|long=no|495}}, and the server version for {{US$|long=no|1495}}. Ostensibly, the server price was meant to be a promotional discount offered only during the first six months of sale, but they never raised the retail price to the listed one—{{US$|long=no|2995}}.<ref name="IW31May1993_S1">{{cite journal | last=Mace | first=Scott | title=NT keeps client/server apps waiting: Database servers will be ready as soon as Microsoft ships delayed OS | journal=InfoWorld | volume=15 | issue=22 | date=1993-05-31 | pages=1 | url= https://books.google.com/books?id=PDsEAAAAMBAJ&pg=PA1}}</ref><ref name="IW19Sep1994_S5">{{cite journal | last=Barney | first=Doug | title=Microsoft set to ship Windows NT 3.5: Will bolster push into enterprise with SMS release | journal=InfoWorld | volume=16 | issue=38 | date=1994-09-19 | pages=5 | url= https://books.google.com/books?id=jDgEAAAAMBAJ&pg=PA5}}</ref> 250 programmers<ref name="IW24May1993_S92">{{cite journal | last=Hixson | first=Amanda | title=Aiming for the high end: An Interview with Paul Thatcher, Microsoft's Windows NT product manager | journal=InfoWorld | volume=15 | issue=21 | date=1993-05-24 | pages=92 | url= https://books.google.com/books?id=PTsEAAAAMBAJ&pg=PA92}}</ref> wrote 5.6 million [[lines of code]];<ref name="ZacharyShowstopper"/>{{rp|page=290}} the development cost {{US$|long=no|150 million}}.<ref name="ZacharyShowstopper"/>{{rp|page=307}} In the last year of development, the team fixed more than 30,000 bugs.<ref name="ZacharyShowstopper"/>{{rp|page=300}}

During the product's lifecycle, Microsoft published three [[service pack]]s: Service Pack 1 was released on October 8, 1993; Service Pack 2 followed on January 24, 1994; and Service Pack 3's release date was October 29, 1994. The service packs were distributed on CD-ROM and floppy disk, and also through [[bulletin board system]]s, [[CompuServe]], and the [[Internet]]. Microsoft terminated support for the operating system on December 31, 2000. Support for Windows NT 3.1 RTM (without a service pack) ended on January 8, 1994. Service Pack 1 support ended on April 24, 1994, and finally, Service Pack 2 support ended on January 29, 1995, only 1 year after general availability.

Windows NT 3.1 was localized into various languages. Besides English, it was available in Dutch, French, German, Japanese, Spanish and Swedish. The version for workstations, but not Windows NT 3.1 Server, was additionally available in Danish, Finnish, Italian, Norwegian and Portuguese.<ref name="mslocale">{{cite web |title=Older Versions of Windows: Windows NT 3.1 |url=http://msdn.microsoft.com/en-us/goglobal/ff678782#Win3.1 |url-status=dead |archive-url=https://web.archive.org/web/20121023012802/http://msdn.microsoft.com/en-us/goglobal/ff678782#Win3.1 |archive-date=2012-10-23 |access-date=2012-10-23 |website=Microsoft Developer Network}}</ref>

== Operating system goals ==
Cutler set three main goals for Windows NT. The first goal was portability: in contrast to previous operating systems, which were strongly tied to one architecture, Windows NT should be able to operate on multiple architectures.<ref name="ZacharyShowstopper"/>{{rp|page=53}} To meet this goal, most of the operating systems, including the operating system core, had to be written in the [[C (programming language)|C programming language]].<ref name="russinovich">{{cite web |last=Russinovich |first=Mark |date=1998-12-01 |title=Windows NT and VMS: The Rest of the Story |url=https://www.itprotoday.com/compute-engines/windows-nt-and-vms-rest-story |access-date=2012-05-19 |website=ITPro Today}}</ref> During the planning phase it was clear that this would cause Windows NT to have higher memory consumption than all previous operating systems.<ref name="ZacharyShowstopper"/>{{rp|page=55}} Besides the graphics system and parts of the networking system, which were written in [[C++]], only parts of the operating systems which required direct hardware access and performance critical functions were written in [[assembly language]]. These parts were isolated so that they could easily be rewritten when porting the operating system to a new architecture.<ref name="Custer1993"/>{{rp|page=89}}

The second goal was [[Reliability engineering|reliability]]: The system should no longer crash due to a faulty application or faulty hardware.<ref name="Custer1993"/>{{rp|page=9}} This way, the operating system should be made attractive for critical applications.<ref name="ZacharyShowstopper"/>{{rp|page=54}} To meet this goal, the architecture of Windows NT was designed so that the operating system core was isolated and applications could not access it directly.<ref name="ZacharyShowstopper"/>{{rp|page=56}} The kernel was designed as a [[microkernel]] and components of the core were to run atop the kernel in a modular fashion; Cutler knew this principle from his work at Digital.<ref name="ZacharyShowstopper"/>{{rp|page=57}} Reliability also includes security, and the operating system should be able to resist external attacks.<ref name="Custer1993"/>{{rp|page=9}} [[Mainframe computer|Mainframe]]s already had a system where every user had their own account which was assigned specific rights by the [[Sysop|administrator]], this way, users could be prevented access to confidential documents.<ref name="Custer1993"/>{{rp|pages=157–158}} A [[virtual memory]] management was designed to thwart attacks by [[malware]] and prevent users from accessing foreign areas of memory.<ref name="Custer1993"/>{{rp|page=10}}

The third goal was called ''personality'': The operating system should be able to run applications designed for various operating systems, such as [[Windows]], MS-DOS and OS/2 applications.<ref name="ZacharyShowstopper"/>{{rp|page=54}} The [[Mach kernel]] followed a similar concept by moving the APIs to components which operated in user mode as applications, these could be changed and new ones could be added. This principle was applied to Windows NT.<ref name="Custer1993"/>{{rp|page=6}}

Despite all these goals, the performance of the operating system was optimized where possible, by adapting critical sections of the code to fast execution speed. To improve networking performance, large parts of the networking system were moved to the operating system core.<ref name="Custer1993"/>{{rp|page=12}}

Windows NT was designed as a networking operating system. In this branch, [[Novell]] had a lead with its product ''NetWare'', mostly because of a lack of competition, and Microsoft failed to develop a product which could challenge NetWare's lead. Cutler hoped to gain additional customers with a reliable networking operating system.<ref name="ZacharyShowstopper"/>{{rp|page=65}} Bill Gates already dominated the market of desktop operating systems with MS-DOS and Windows and hoped to do the same in the networking market with Windows NT.<ref name="ZacharyShowstopper"/>{{rp|page=3}} He especially hoped to find a market in the emerging number of servers, while at the same time he did not expect a success in the desktop market until 1995.<ref name="ZacharyShowstopper"/>{{rp|page=151}}

Therefore, Windows NT was positioned as a high-end operating system in an interview with the product manager David Thacher. It was not designed to replace Windows 3.1 completely, but it should rather supplement Microsoft's product palette with an operating system for critical applications. The expectations were 10% to 20% among all Windows sales<ref name="IW24May1993_S92" /> and a market share of 10% in the high end market, which amounted to one million copies.<ref name="IW24May1993_S85">{{cite journal | last=Hixson | first=Amanda | title=Building an infrastructure: Microsoft recognizes that it needs solid partnerships to give it credibility at the high end | journal=InfoWorld | volume=15 | issue=21 | date=1993-05-24 | pages=85 | url= https://books.google.com/books?id=PTsEAAAAMBAJ&pg=PA85}}</ref>

== Features ==
=== Architecture ===
While Windows NT 3.1 uses the same graphical user interface as Windows 3.1, it was developed anew. The operating system is not DOS-based, but an independent 32-bit operating system; many concepts were taken from Cutler's previous operating system, [[OpenVMS|VMS]].<ref name="russinovich" /> The [[architecture of Windows NT]] takes some ideas of the [[client–server model]], like the modular structure and the communication between the modules.<ref name="Custer1993"/>{{rp|page=20}} System resources like memory, files or devices are viewed as [[Object (computer science)|object]]s by the operating system, which are all accessed in the same way through [[Handle (computing)|handles]] and which can in this way be secured against unauthorized access.<ref name="Custer1993"/>{{rp|pages=22–23}}

The operating system was designed for multiprocessor systems; it supports [[preemptive multitasking]]<ref name="Custer1993"/>{{rp|page=92}} and can make use of [[Thread (computing)|threads]] to run multiple processes in parallel.<ref name="Custer1993"/>{{rp|page=94}} Using [[symmetric multiprocessing]], the processing usage is evenly distributed among all available processors.<ref name="Custer1993"/>{{rp|page=24}} The [[inter-process communication]] in Windows NT 3.1 is designed around networks; two newly introduced functions, [[Remote Procedure Call]] (RPC) and [[Network DDE]], an extension of [[Dynamic Data Exchange]] (DDE), facilitate the access and data exchange between processes running on different computers inside a network.<ref name="PCMag28Sep1993_S211">{{cite journal| last1=Ayre | first1=Rick | last2=Raskin | first2=Robin | title=Windows NT: See how it runs | journal=PC Magazine | volume=12 | issue=16 | date=1993-09-28 | pages=211–231 |issn=0888-8507 | url= https://books.google.com/books?id=5KSmAXszIQYC}}</ref>

The operating system is designed to combine certain elements of a [[monolithic kernel]] and a microkernel;<ref name="Custer1993"/>{{rp|page=20}} nowadays this is most often referred to as a [[hybrid kernel]].<ref name="mskernel">{{cite web |date=February 20, 2014 |title=MS Windows NT Kernel-mode User and GDI White Paper |url=https://technet.microsoft.com/library/cc750820.aspx |access-date=2012-06-07 |website=Microsoft}}</ref> The [[hardware abstraction layer]] represents the lowermost layer and isolates the operating system from the underlying hardware to make it easy to port the operating system to other platforms.<ref name="Custer1993"/>{{rp|page=30}} The kernel running atop only has very basic functions like [[interrupt]] management and processor synchronization. All other functions of the operating system core are handled by modules<ref name="Custer1993"/>{{rp|page=20}} which operate independently from one another and can be swapped without affecting the rest of the operating system.<ref name="Custer1993"/>{{rp|page=28}}

Positioned above the operating system core are the subsystems. There are two types of subsystems: one are the ''integral subsystems'', which perform important operating system functions. One such subsystem is the security subsystem, which handles the logon process and monitors the security of the system. The other type of subsystem is the ''environment subsystem'', which exposes the operating system functions to applications via [[application programming interface]]s.<ref name="Custer1993"/>{{rp|page=27}} The base subsystem is the 32-bit subsystem which runs 32-bit applications written for Windows NT. Windows NT applications can only run on one platform, and must be recompiled for every platform. The 32-bit subsystem also contains all [[output (computing)|output]] functions, including the [[Graphics Device Interface]] (GDI),<ref name="ct1993">{{cite journal | last=Siering | first=Peter | title=Paarige Premiere: Microsoft Windows NT 3.1 und Advanced Server | journal=C't | issue=11 | year=1993 | pages=142 ff}}</ref> so all other subsystems have to call the 32-bit subsystem to be able to output text or graphics.<ref name="Custer1993"/>{{rp|page=33}} Other subsystems contained in Windows NT 3.1 are the POSIX subsystem, which supports POSIX-compatible applications built for Windows NT, and, in the x86 version only, the OS/2 subsystem, which allows command-line based OS/2 1.x applications to run.<ref name="ct1993" />

The [[Virtual DOS Machine]] (VDM) is sometimes also viewed as a subsystem, but is, strictly speaking, a normal 32-bit Windows application. It manages applications originally built for DOS. Built on top is [[Windows on Windows]] (WoW), which allows applications built for 16-bit Windows operating systems like Windows 3.1 to run. On x86 computers, the virtual DOS machine uses the [[virtual 8086 mode]] to run DOS applications directly,<ref name="ct1993" /> on RISC computers, an emulator licensed from ''Insignia Solutions'' is used which emulates a [[80286]] processor. However, not all DOS and 16-bit Windows applications can be run on Windows NT 3.1 due to various limitations,<ref name="ct1994">{{cite journal |last=Siering |first=Peter |year=1994 |title=Lizenz-Rezepte: Windows NT 3.5 Workstation und Server |journal=C't – Magazin für Computertechnik |issue=12 |pages=266}}</ref> one of them being the inability of applications to directly access the hardware. As well, [[VxD]] files sometimes needed by applications cannot be used with Windows NT 3.1.<ref name="msq103012">{{Cite web|url=http://support.microsoft.com/kb/103012/en-us|title=Virtual Device Drivers (VXDs) Do Not Work in Windows NT|date=April 8, 2004|website=Microsoft Support|archive-url=https://web.archive.org/web/20130227071247/http://support.microsoft.com/kb/103012/en-us|archive-date=February 27, 2013|access-date=May 9, 2019}}</ref> While pure DOS applications are run in separate memory spaces, 16-bit Windows applications have to share one memory space. While this is done due to compatibility reasons with applications which depend on this ability, like [[Schedule+]] and [[Microsoft Mail]], it also means that 16-bit Windows applications only run in [[cooperative multitasking]]. A faulty 16-bit Windows application is in this way able to cause all other 16-bit Windows applications (but not Windows NT itself) to crash.<ref name="ct1993" />

[[Image:NT 3.1 layers.png|thumb|center|600px|Graphical view of the architecture of Windows NT 3.1. Shown are the following components of the operating system core: I/O Manager, Object Manager, Security Reference Monitor, Process Manager, Local Procedure Call Facility, Virtual Memory Manager.<ref name="Custer1993"/>{{rp|pages=26–33}}]]

=== System ===
Windows NT 3.1 provides a [[boot manager]] called [[NTLDR]] which is loaded during the startup process of the operating system on x86-based computers. It allows a multiboot setup of multiple instances of Windows NT 3.1, as well as MS-DOS and OS/2 1.x.<ref name="msq106168">{{Cite FTP | title=Microsoft Knowledge Base – Windows NT Multi-Boot Support Limitations | url=ftp://ftp.microsoft.com/MISC1/BUSSYS/WINNT/KB/Q106/1/68.TXT | server=FTP server | url-status=dead | access-date=2012-06-08 }}</ref> NTLDR is not used for the RISC versions because the RISC computers' firmware provides their own boot manager.<ref name="msstartup">{{cite web | title=Windows NT Resource Kit – Chapter 19 – What Happens When You Start Your Computer| url=https://technet.microsoft.com/en-us/library/cc750074 | access-date= 2012-06-08}}</ref>

Every user has to log on to the computer after Windows NT 3.1 is booted up by pressing the key combination [[Control-Alt-Delete|Ctrl+Alt+Del]] and entering the user name and password. All users have their own [[user account]], and user-specific settings like the [[Program Manager]] groups are stored separately for every user. Users can be assigned specific rights, like the right to change the system time or the right to shut down the computer. To facilitate management of user accounts, it is also possible to group multiple user accounts and assign rights to groups of users.<ref name="ct1993" />

Windows NT 3.1 introduced the new [[NTFS]] file system. This new file system is more robust against hardware failures<ref name="Custer1993"/>{{rp|page=10}} and allows assignment of read and write rights to users or groups on the file system level.<ref name="ct1993" /> NTFS supports long file names<ref name="ct1993" /> and has features to accommodate POSIX applications like [[hard link]]s.<ref name="Custer1993"/>{{rp|page=39}} For compatibility reasons, Windows NT 3.1 also supports [[FAT16]] as well as OS/2's file system [[High Performance File System|HPFS]],<ref name="ct1993" /> but does not support long file names on FAT file system ([[VFAT]]). This was added in Windows NT 3.5.

Designed as a networking operating system, Windows NT 3.1 supports multiple [[network protocol]]s. Besides [[IPX/SPX]] and [[NetBEUI]], the [[TCP/IP]] protocol is supported allowing access to the Internet.<ref name="ct1993" /> Similar to ''Windows for Workgroups'', files and printers can be shared and the access rights and configuration of these resources can be edited over the network. When a network printer is installed, the required drivers are automatically transferred over the network, removing the need to manually install the drivers for every computer.<ref name="ct1993" /> The [[Remote Access Service]] (RAS) allows a client from outside the network to connect to the network using a [[modem]], [[ISDN]] or [[X.25]] and access its resources. While the workstation allows one RAS connection at a time, the server supports 64.<ref name="ct1993" />

Windows NT 3.1 supports the then-new [[Unicode]] standard, a [[character set]] which allows multiple languages to be displayed. This facilitates [[Internationalization and localization|localization]] of the operating system.<ref name="msq99884">{{Cite web |date=November 4, 2003 |title=Unicode and Microsoft Windows NT |url=http://support.microsoft.com/kb/99884/EN-US/ |archive-url=https://web.archive.org/web/20041205100017/http://support.microsoft.com/kb/99884/EN-US/ |archive-date=December 5, 2004 |access-date=May 9, 2019 |website=Microsoft Support}}</ref> All strings, as well as file and folder names, are internally processed in Unicode,<ref name="Custer1993"/>{{rp|page=43}} but the included programs, like the [[File Manager]], are not Unicode aware, so folders containing Unicode characters cannot be accessed.<ref name="msq102384">{{Cite web|url=http://support.microsoft.com/kb/102384/en-us|title=Windows NT File Manager: Services for Macintosh Concerns|date=October 31, 2006|website=Microsoft Support|archive-url=https://web.archive.org/web/20130227071307/http://support.microsoft.com/kb/102384/en-us|archive-date=February 27, 2013|access-date=May 9, 2019}}</ref> For demonstration purposes, a [[Unicode typeface]] called ''[[Lucida]] Sans Unicode'' is shipped with Windows NT 3.1<ref name="bigelow">{{cite journal | last1=Bigelow | first1=Charles | last2=Holmes | first2=Kris | title=The design of a Unicode font | journal=Electronic Publishing | volume=6 | issue=3 | date=September 1993 | pages=289–305 | url= http://cajun.cs.nott.ac.uk/wiley/journals/epobetan/pdf/volume6/issue3/bigelow.pdf | format=PDF; 0,5 MB |issn=0894-3982}}</ref> even though it is not installed by default. The previous [[code page]]s are still supported for compatibility purposes.<ref name="msq99884" />

The [[Windows registry]], introduced with Windows 3.1, is a central, hierarchical configuration database<ref name="ct1993" /> designed to allow configuration of computers over the network<ref name="ZacharyShowstopper"/>{{rp|page=251}} and to replace the commonly-used text-based configuration files, like [[INI file]]s, [[AUTOEXEC.BAT]] and [[CONFIG.SYS]].<ref name="Custer1993"/>{{rp|page=327}} Using the undocumented registry editor, the Windows registry can be viewed and edited by the user.<ref name="ct1993" />

The ''Advanced Server'' is designed to manage the workstation computers.<ref  name="ct1993" /> It can function as a [[Domain controller]], where all users and groups as well as their rights are stored. This way, a user can log on from any computer in the network, and users can be managed centrally on the server. Trust relationships can be built to other domains to be able to exchange data cross-domain.<ref name="ct1993" /> Using the [[Replication (computing)|replication]] service, files like logon scripts can be synchronized across all computers on the network. The Advanced Server supports the [[AppleTalk]] protocol to allow connections to Macintosh computers.<ref name="ct1993" /> Hard drives can be combined to [[RAID]]s in Windows NT 3.1 Advanced Server, the supported configurations are RAID 0, RAID 1 and RAID 5.

=== Included programs ===
Windows NT 3.1, for the most part, comes with 32-bit versions of the components featured in Windows 3.1 and Windows for Workgroups. However, it also included applications specifically aimed at the needs of Windows NT, like the User Manager, the [[Performance Monitor]], the Disk Administrator, the [[Event Viewer]] and the ''Backup'' application. The ''Advanced Server'' contained further, server-specific administration tools. Because Windows NT 3.1 is not DOS-based, a new 32-bit command-line processor, called [[CMD.EXE]] was included which was compatible with MS-DOS 5.0.<ref name="ct1993" /> For compatibility reasons, Windows NT 3.1 shipped with a few 16-bit applications, like [[Microsoft Write]] or [[EDLIN]].<ref name="msq101929">{{Cite web|url=http://support.microsoft.com/kb/101929/en-us|title=16-Bit Applications Included with Windows NT|date=October 31, 2006|website=Microsoft Support|archive-url=https://web.archive.org/web/20130227071235/http://support.microsoft.com/kb/101929/en-us|archive-date=February 27, 2013|access-date=May 9, 2019}}</ref>

Windows NT 3.1, being an all-new operating system for which no previous MS-DOS based drivers could be used, includes a wealth of drivers for various common components and peripherals.<ref name="ct1994" /> This includes common [[SCSI]] devices like hard drives, CD-ROM drives, [[tape drive]]s and [[image scanner]]s,<ref name="msq103284">{{Cite web|url=http://support.microsoft.com/kb/103284|title=Contents of Windows NT SETUP.TXT, Part 1|date=October 31, 2006|website=Microsoft Support|archive-url=https://web.archive.org/web/20091031110903/http://support.microsoft.com/kb/103284|archive-date=October 31, 2009|access-date=May 9, 2019}}</ref> as well as [[Industry Standard Architecture|ISA]] devices like graphics cards, sound cards and network cards. The [[EISA bus|EISA]] bus, is supported by Windows NT 3.1. The [[Conventional PCI|PCI bus]], however, is not supported by kernel, but supported by third-party drivers.<ref name="msq113345">{{Cite web|url=http://support.microsoft.com/kb/113345/en-us|title=Support for PCI Computers and Peripherals in Windows NT 3.1|date=October 31, 2006|website=Microsoft Support|archive-url=https://web.archive.org/web/20130227071227/http://support.microsoft.com/kb/113345/en-us|archive-date=February 27, 2013|access-date=May 9, 2019}}</ref> Windows NT 3.1 supports an [[uninterruptible power supply]].<ref name="Custer1993"/>{{rp|page=328}}

Windows NT 3.1 could be installed either by using the CD-ROM and a provided [[boot disk]], or by utilizing a set of twenty-two 3.5" floppies (twenty-three floppies for ''Advanced Server''). Windows NT 3.1 could also be installed over the network.<ref name="ct1993" /> A coupon was included that made it possible to order a set of twenty-seven 5.25" floppies (or twenty-eight floppies for ''Advanced Server'').<ref name="computinghistory">{{cite web |title=Microsoft Windows NT version 3.1 |url=http://www.computinghistory.org.uk/det/12535/Microsoft-Windows-NT-version-3-1/ |access-date=2012-09-06 |website=Centre for Computing History}}</ref> Compared to the floppies, the CD-ROM contained additional drivers and applications.

Windows NT 3.1 does not support [[ATAPI]] CD-ROMs.

== System requirements ==
Windows NT 3.1 supports multiple platforms: Aside from the x86 architecture, it runs on computers with [[DEC Alpha]] or [[MIPS Technologies|MIPS]] ([[R4000]] and [[R4400]]) processors.<ref name="IW6Dec1993_S15">{{cite journal | title=Microsoft-Werbung | journal=InfoWorld | volume=15 | issue=49 | date=1993-12-06 | pages=15 | url= https://books.google.com/books?id=9zoEAAAAMBAJ&pg=PA15}}</ref>

Minimum system requirements on x86 systems include a 25&nbsp;MHz [[80386]] processor, at least 12 megabytes of memory, 75 megabytes of hard drive space, and a VGA graphics card. [[RISC]] systems require 16 megabytes of memory, 92 megabytes of hard drive space, and a CD-ROM drive.<ref name="winhistory">{{cite web |title=Windows NT 3.1 |url=http://www.winhistory.de/more/nt31.htm |url-status=dead |archive-url=https://web.archive.org/web/20080119051131/http://www.winhistory.de/more/nt31.htm |archive-date=January 19, 2008 |access-date=2012-09-05 |website=Winhistory}}</ref> The ''Advanced Server'' edition requires an 80386 processor with 16 megabytes of memory and 90 megabytes of hard drive space. On RISC systems, 110 megabytes of hard drive space is needed.<ref name="IW15Nov1993_S138">{{cite journal | last1=Strom | first1=David | last2=Capen | first2=Tracey | last3=Crawford | first3=Tim | last4=Gallie | first4=Rodney | last5=Chapin | first5=Rod | title=A bumper crop of network operating systems brings centralized management, application services, and more capable clients to the enterprise | journal=InfoWorld | volume=15 | issue=46 | date=1993-11-15 | pages=138–150 | url= https://books.google.com/books?id=DDsEAAAAMBAJ&pg=PA138}}</ref>

Windows NT 3.1 supports dual processor systems, while the ''Advanced Server'' edition supports up to four processors. Due to an error in the processor detection routine, Windows NT 3.1 cannot be installed on [[Pentium II]] or newer processors. Microsoft never fixed the problem, but [[unofficial patch]]es are available.<ref name="winhistory" />

== Reception ==
Windows NT 3.1 sold about 300,000 copies in its first year.<ref name="ctrueckblick">{{cite web |date=July 27, 2003 |title=Zehn Jahre Windows NT |url=http://www.heise.de/ct/artikel/Zehn-Jahre-Windows-NT-ein-Rueckblick-301948.html |access-date=2012-06-09 |website=c't – Magazin für Computertechnik}}</ref> The hardware requirements were deemed to be very high at that time; the recommended system requirements of a 486 processor with 16 megabytes of memory were well above the average computer's configuration,<ref name="ct1994" /> and the operating system turned out to be too slow to use.<ref name="IW16Aug1993_S1">{{cite journal | last1=Strehlo | first1=Kevin | last2=Gallie | first2=Rodney | title=Windows NT: a robust server but a poor OS | journal=InfoWorld | volume=15 | issue=33 | date=1993-08-16 | pages=1, 100 | url= https://books.google.com/books?id=qjsEAAAAMBAJ&pg=PA1}}</ref> 32-bit applications which could have used the capabilities of Windows NT 3.1 were scarce, so users had to resort to the old 16-bit applications; however, these ran slower than on Windows 3.1. Estimates in November 1993 counted only 150 Windows NT applications.<ref name="IW15Nov1993_S84">{{cite journal | last=Korzeniowski | first=Paul | title=More than just a print and file server | journal=InfoWorld | volume=15 | issue=46 | date=1993-11-15 | pages=84 | url= https://books.google.com/books?id=DDsEAAAAMBAJ&pg=PA84}}</ref> Common types of software, like [[office suite]]s, were not available for Windows NT 3.1.<ref name="ct1994" /> During the development of the operating system, the API calls were changed so 32-bit applications built on the 1992 pre-release version of Windows NT 3.1 could not be run on the final version. This affected software such as [[Microsoft Visual C++]] 1.0 and Microsoft Fortran PowerStation.<ref name="msq103621">{{Cite web|url=http://support.microsoft.com/kb/103621/en-us|title=Running Visual C++ for Windows with Windows NT|date=November 1, 2006|website=Microsoft Support|archive-url=https://web.archive.org/web/20130227071254/http://support.microsoft.com/kb/103621/en-us|archive-date=February 27, 2013|access-date=May 9, 2019}}</ref>

RISC systems with Windows NT 3.1 had an even bigger disadvantage: even though they were more powerful than x86 systems,<ref name="PCMag28Sep1993_S211" /> almost no 32-bit applications or drivers were ported to these platforms.<ref name="ctrueckblick" /> 16-bit applications ran much slower under RISC systems because of the 80286 emulation compared to x86 systems which could run 16-bit applications natively,<ref name="PCMag28Sep1993_S211" /> and DOS and 16-bit applications which depended on 386 calls could not be run at all on RISC systems.

However, not all reception was negative; the multitasking capabilities of the operating system were rated positively, especially compared to Windows 3.1.<ref name="ct1993" /> Compared to the size of the operating system, the installation turned out to be very easy, even though installing from floppies was a very time-consuming task.<ref name="IW15Nov1993_S96">{{cite journal | last=Howell | first=Dave | title=Diary of an NT install: With a small amount of preparation and the right hardware, installing NT is a no-brainer | journal=InfoWorld | volume=15 | issue=46 | date=1993-11-15 | pages=96–98 | url= https://books.google.com/books?id=DDsEAAAAMBAJ&pg=PA96}}</ref> The ''Advanced Server'', intended to be the successor to the unsuccessful [[LAN Manager]] product, was technically much superior to its predecessor, and only failed to gain success because it shared the same problems with its workstation pendant, such as the low performance running 16-bit applications.<ref name="IW15Nov1993_S81">{{cite journal | last=Korzeniowski | first=Paul | title=Windows NT Advanced Server: The new network OS seems to be on a slow climb toward acceptance | journal=InfoWorld | volume=15 | issue=46 | date=1993-11-15 | pages=81 | url= https://books.google.com/books?id=DDsEAAAAMBAJ&pg=PA81}}</ref> The ''Advanced Server'' provided a financial advantage for large networks because its price was not dependent on the number of clients, unlike its competitor Novell NetWare.<ref name="IW15Nov1993_S138" />

With Windows NT, Microsoft entered a market it could not previously address and which was mostly dominated by Unix, Novell NetWare and OS/2.<ref name="IW15Nov1993_S77">{{cite journal | last1=Korzeniowski | first1=Paul | last2=Barney | first2=Doug | title=Which Windows when, where and why? Do you need to know the way to Cairo and Chicago? And how long will it take to get there? | journal=InfoWorld | volume=15 | issue=46 | date=1993-11-15 | pages=77 f | url= https://books.google.com/books?id=DDsEAAAAMBAJ&pg=PA77}}</ref> A test performed by the [[InfoWorld]] magazine in November 1993, where the networking capabilities of several operating systems were tested, showed that Windows NT 3.1 was seriously lacking in inter-client communication: it could only connect to its own server via [[NetBEUI]]; attempts to connect to Unix, NetWare and OS/2 all failed because no client software was available. For the ''Advanced Server'', only their own client, the Macintosh and, if only limited, OS/2 were able to connect to the server.<ref name="IW15Nov1993_S124">{{cite journal | last1=Perele | first1=Nicholas | last2=Durlester | first2=Nancy | last3=Wonnacott | first3=Laura | last4=Sommer | first4=Dan | title=The interoperability headache: linking disparate clients and servers: The mission: to give each of eight client operating systems simultaneous access to the leading networks and printers in our testing enterprise | journal=InfoWorld | volume=15 | issue=46 | date=1993-11-15 | pages=124–134 | url= https://books.google.com/books?id=DDsEAAAAMBAJ&pg=PA124}}</ref>

Even though the operating system's actual success was only moderate, it had a huge lasting impact. Developers of Unix derivations for the first time strived to standardize their operating systems, and Novell was so concerned about its market share that it bought a Unix vendor.<ref name="ZacharyShowstopper"/>{{rp|page=303}} Manufacturers of [[microprocessor]]s hoped to use the portability of the new operating system to increase their own sales,<ref name="ZacharyShowstopper"/>{{rp|page=303}} and thus ports of Windows NT were announced for various platforms, like the [[Sun SPARC]] architecture<ref name="IW12Jul1993_S8">{{cite journal | last1=Johnston | first1=Stuart J. | last2=Wilson | first2=Jayne | title=Sun, Intergraph to port Windows NT to RISC-based Sparc systems | journal=InfoWorld | volume=15 | issue=28 | date=1993-07-12 | pages=8 | url= https://books.google.com/books?id=SDsEAAAAMBAJ&pg=PA8}}</ref> and the [[Clipper architecture]].<ref name="IW23Nov1992_S16">{{cite journal | last=Johnston | first=Stuart J. | title=Intergraph to port its Unix-based engineering apps to Windows NT | journal=InfoWorld | volume=14 | issue=47 | date=1992-11-23 | pages=16 | url= https://books.google.com/books?id=LlEEAAAAMBAJ&pg=PA16}}</ref> It was recognized that Windows NT would dominate the desktop market as soon as the hardware became powerful enough to run the operating system at an acceptable speed.<ref name="IW22Nov1993_S66">{{cite journal | last1=Kent | first1=Les | last2=Armstrong | first2=James | last3=Nash | first3=Siobhan | title=32-bit desktop operating systems: Finding the right operating system to suit your needs | journal=InfoWorld | volume=15 | issue=47 | date=1993-11-22 | pages=66–83 | url= https://books.google.com/books?id=ATsEAAAAMBAJ&pg=PA66}}</ref> Eight years later, Microsoft would unify the consumer-oriented Windows line (which had remained MS-DOS based) with the NT line with the October 2001 release of [[Windows XP]]—the first consumer-oriented version of Windows to use the NT architecture.<ref name="cnet-xpreview">{{cite web |date=September 4, 2001 |title=Windows XP review |url=http://reviews.cnet.com/windows/microsoft-windows-xp-home/4505-3672_7-6534881.html |access-date=24 May 2013 |publisher=CNET}}</ref>

== Support lifecycle ==
{{Timeline Windows NT 3.x}}

== References ==
{{reflist}}

== External links ==
* [http://www.guidebookgallery.org/guis/windows/winnt31 Guidebook: Windows NT 3.1 Gallery]&nbsp;– Gallery of UI screenshots of Windows NT 3.1

{{Microsoft Windows family}}
{{Authority control}}

[[Category:1993 software]]
[[Category:Products and services discontinued in 2000]]
[[Category:Windows NT|3.1]]
[[Category:IA-32 operating systems]]
[[Category:MIPS operating systems]]
[[Category:History of Microsoft]]
[[Category:History of software]]
[[Category:Products introduced in 1993]]
[[Category:Microsoft Windows]]