- Not to be confused with Windows Server.
Windows NT is a family of operating systems produced by Microsoft, the first version of which was released on July 27, 1993. It is a processor-independent, multiprocessing and multi-user operating system, designed to complement workstation versions of Windows that were based on MS-DOS (including Windows 1.0 through Windows 3.1x). Gradually, the Windows NT family was expanded into Microsoft's general-purpose operating system product line for all personal computers, deprecating the Windows 9x family.
"NT" was originally an acronym for "New Technology", but no longer carries any specific meaning and, starting with Windows 2000, "NT" was removed from the product name and is only included in the product version string.
NT was the first 32-bit version of Windows, whereas its previous consumer-oriented counterparts, Windows 3.1x and Windows 9x, were 16-bit/32-bit hybrids.
Product line
Windows NT is a group or family of products, just as Windows is a group or family. Windows NT is a sub-grouping of Windows.
The first version of Windows NT, 3.1, was produced for workstation and server computers. It was commercially focused and intended to complement consumer versions of Windows that were based on MS-DOS (including Windows 1.0 through Windows 3.1x). In 1996, Windows NT 4.0 was released, including the new shell from Windows 95.
Eventually, Microsoft incorporated the Windows NT technology into the Windows product line for personal computing and deprecated the Windows 9x family. Starting with Windows 2000, "NT" was removed from the product name, yet is still in several low-level places in the system – including as a part of the product version.
Naming
It has been suggested that Dave Cutler intended the initialism "WNT" as a play on VMS, incrementing each letter by one. 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. Two of the original NT developers, Mark Lucovsky and Dave Plummer, state that the name was taken from the original target processor – the Intel i860, codenamed N10 ("N-Ten"). A 1991 video featuring Bill Gates and Microsoft products specifically says that "Windows NT stands for 'New Technology'". Seven years later, in 1998, during a Q&A session, he then revealed that the letters were previously expanded to such but no longer carry any specific meaning. The letters were dropped from the names of releases from Windows 2000 onward, though Microsoft described that product as being "Built on NT Technology".
Major features
One of the main purposes of NT is hardware and software portability. Various versions of the NT family of 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. An initial idea was to have a common codebase with a custom Hardware Abstraction Layer (HAL) for each platform. However, support for MMIPS, Alpha, and PowerPC was later dropped in Windows 2000. Broad software compatibility was initially achieved with support for several API "personalities", including Windows API, POSIX, and OS/2 API – the latter two were phased out starting with Windows XP. Partial MS-DOS and Windows 16-bit compatibility is achieved on IA-32 via an integrated DOS Virtual Machine – although this feature is not available on other architectures.
NT has 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 has also supported Windows network protocols, including the previous OS/2 LAN Manager networking, as well as TCP/IP networking (for which Microsoft used to implement a TCP/IP stack derived at first from a STREAMS-based stack from Spider Systems, then later rewritten in-house).
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 switched 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 applications (although MS-DOS applications were preemptively multitasked in Windows starting with Windows/386).
Notably, in Windows NT 3.x, several I/O driver subsystems, such as video and printing, were user-mode subsystems. In Windows NT 4.0, 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 4.0'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, is a major feature of NT. Windows NT also allows for other installable file systems; NT can also be installed on FAT file systems, and versions 3.1, 3.5, and 3.51 could be installed on HPFS file systems.
Windows NT introduced its own driver model, the Windows NT driver model, which 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. 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.
NT has grown from being called "Nice Try" to passing Unix in 2005 for sales of servers according to IDC, a market research firm based in Framingham, Mass. Others observe that Windows NT servers using IIS, ASP and ASP.NET by the 2000s had a diminishing share of web and corporate servers (under 30%) with UNIX dominating with over 70% of the market. The entry level $99 workstation Windows XP lacks the ability to run SQL Server databases and IIS web servers and other corporate features found in Professional and Server versions, but NT is now a major platform for PC based games. Since NT has become the base technology for workstations, it nearly completely dominates desktop and laptop workstations with Apple a distant second and Linux yet fewer.
Development
Windows NT wordmark for version 4.0.
Microsoft decided to create a portable operating system, compatible with OS/2 and POSIX and supporting multiprocessing, in October 1988. When development started in November 1989, Windows NT was to be known as OS/2 3.0, 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. 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 3.0 was eventually so successful that Microsoft decided to change the primary API 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, VAXELN, and RSX-11, but also an unreleased object-based operating system developed by Cutler at Digital named MICA. The team was joined by selected members of the disbanded OS/2 team, including Moshe Dunie.
Although NT was not an exact clone of Cutler's previous operating systems, DEC engineers almost immediately noticed the internal similarities. Parts of VAX/VMS Internals and Data Structures, published by Digital Press, accurately describe Windows NT internals using VMS terms. Furthermore, parts of the NT codebase's directory structure and filename matched that of the MICA codebase. Instead of a lawsuit, Microsoft agreed to pay DEC $65-100 million, help market VMS, train Digital personnel on Windows NT, and continue Windows NT support for DEC Alpha.
Windows NT and VMS memory management, processes, and scheduling are very similar. Windows NT's process management differs by implementing threading, which DEC did not implement until VMS 7.0 in 1995.
Like VMS, Windows NT's kernel mode code 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 by Richard Rashid at Carnegie Mellon University, but it 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; it was this that allowed the late adoption of the Windows API (into the Win32 subsystem). Windows NT was one of the earliest operating systems to use UCS-2 and UTF-16 internally.
Architecture
- Main article: Architecture of Windows NT
Windows NT uses a layered design architecture that consists of two main components, user mode and kernel mode. Programs and subsystems in user mode are limited in terms of what system resources they have access to, while the kernel mode has unrestricted access to the system memory and external devices. Kernel mode in Windows NT has full access to the hardware and system resources of the computer. The Windows NT kernel is a hybrid kernel; the architecture comprises a simple kernel, a hardware abstraction layer (HAL), drivers, and a range of services (collectively named Executive), which all exist in kernel mode.
The booting process of Windows NT begins with NTLDR in versions before Vista and the Windows Boot Manager in Vista and later. The boot loader is responsible for accessing the file system on the boot drive, starting the kernel, and loading boot-time device drivers into memory. Once all the boot and system have been loaded, the kernel starts the Session Manager Subsystem. This process launches winlogon, which allows the user to log in. Once the user is logged in, File Explorer is started, loading the graphical user interface of Windows NT.
Programming language
Windows NT is written in C and C++, with a very small amount written in assembly language. C is mostly used for the kernel code, while C++ is mostly used for user-mode code. Assembly language is avoided where possible because it would impede portability, and its usage is limited to just the most performance-critical portions (e.g., trap handlers, interrupt dispatch, system call stubs, content switching, HAL low-level routines) of the codebase.
Releases
| NT Ver. | Marketing Name | Editions | Release Date | Build |
|---|---|---|---|---|
| NT 3.1 | Windows NT 3.1 | Workstation (named just Windows NT), Advanced Server | July 27, 1993 | 528 |
| NT 3.5 | Windows NT 3.5 | Workstation, Server | September 21, 1994 | 807 |
| NT 3.51 | Windows NT 3.51 | Workstation, Server | May 30, 1995 | 1057 |
| NT 4.0 | Windows NT 4.0 | Workstation, Server, Server Enterprise Edition, Terminal Server, Embedded | July 29, 1996 | 1381 |
| NT 5.0 |
Windows 2000 x64 |
Professional, Server, Advanced Server, Datacenter Server, Media Center, Starter, Embedded | February 17, 2000 | 2195 |
| NT 5.1 | Windows XP | Home, Professional, IA64, Media Center (2002, 2003, 2004 & 2005), Tablet PC, Starter, Embedded, N | October 25, 2001 | 2600 |
| NT 5.2 | Windows Server 2003 | Standard, Enterprise, Datacenter, Web, Small Business Server | April 24, 2003 | 3790 |
| NT 5.2 | Windows XP (x64) | Professional x64 Edition | April 25, 2005 | 3790 |
| NT 6.0 | Windows Vista | Starter, Home Basic, Home Premium, Business, Enterprise, Ultimate | Business: November 2006 Consumer: January 2007 |
6000 (RTM)
6001 (SP1) 6002 (SP2) |
| NT 6.0 | Foundation, Standard, Enterprise, Datacenter, Web Server, HPC Server, Itanium-Based Systems | February 27, 2008 | 6000 (RTM)
6001 (SP1) 6002 (SP2) | |
| NT 6.1 | Professional, Home Premium, Ultimate | October 22, 2009 | 7600 (RTM)
7601 (SP1) | |
| NT 6.1 | Windows Server 2008 R2 | Foundation, Standard, Enterprise, Datacenter, Web Server, HPC Server, Itanium-Based Systems | October 22, 2009 | 7600 (RTM)
7601 (SP1) |
| NT 6.2 | Windows 8 | Home, Pro, Enterprise, RT | October 26, 2012 | 9200 |
| NT 6.2 | Windows Server 2012 | Foundation, Essentials, Standard, Datacenter | September 4, 2012 | 9200 |
| NT 6.3 | Windows 8.1 | Home, Pro, Enterprise, RT 8.1 | October 17, 2013 | 9600 |
| NT 6.3 | Windows Server 2012 R2 | Foundation, Essentials, Standard, Datacenter | October 17, 2013 | 9600 |
| NT 10.0 | Windows 10 | Home, Pro, Pro Education, Enterprise, Education, Windows 10 S, IoT Core, Mobile, Mobile Enterprise | July 29, 2015 | 10240 (TH1)
10586 (TH2) 14393 (RS1) 15063 (RS2) 16299 (RS3) 17134 (RS4) |
| NT 10.0 | Windows Server 2016 | Essentials, Standard, Datacenter, Multipoint Premium Server, Storage Server, Hyper-V Server | October 12, 2016 | 14393 (RS1)
16299 (RS3) |
| NT 10.0 | Windows Server 2019 | Essentials, Standard, Datacenter | October 2, 2018 | 17763 |
| NT 10.0 | Windows Server 2022 | Essentials, Standard, Datacenter | August 18, 2021 | 20348 |
| NT 10.0 | Windows 11 | Home, Pro, Education, Enterprise | October 5, 2021 | 22000 (21H2/RTM) |
| NT 10.0 | Windows Server 2025 | Essentials, Standard, Datacenter, Multipoint Premium Server, Hyper-V Server | November 1, 2024 | 26100 |
Windows NT 3.1 to 3.51 incorporated the Program Manager and File Manager from the Windows 3.1 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.
The NT version number is not generally used for marketing purposes anymore, but it is still used internally, and said to reflect the changes to the core of the operating system. However, for application compatibility reasons, Microsoft kept the major version number as 6 in releases following Vista, but later changed it to 10 for Windows 10. The build number is an internal identifier used by Microsoft's developers and beta testers.
Starting with Windows 8.1, Microsoft changed the Version API Helper functions' behavior. If an application is not manifested for Windows 8.1, the API will always return version 6.2, which is the version number for Windows 8. This is because the manifest feature was introduced with Windows 8.1, to replace GetVersion and related functions.
Supported platforms
Like Unix, NT was written in a high-level language such as C. It can be recompiled to run on other processor systems, at the expense of larger and slower code. For this reason, NT was not favored initially for use with slower processors with less memory. It also 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, nearly all actual NT deployments have been on x86 architecture processors.
Windows NT 3.1 ran on Intel IA-32 x86, DEC Alpha, and MIPS R4000 processors. Windows NT 3.51 added support for PowerPC processors. Intergraph Corporation ported Windows NT to its Clipper architecture and later SPARC, but neither version was sold to the public. Windows NT 4.0 was the last major release to support Alpha, MIPS, or PowerPC, though development of Windows 2000 for Alpha continued until 1999, when Compaq stopped support for Windows NT on that architecture. 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 3rd parties (Motorola, Intergraph, etc.) have few, if any, publicly available updates.
Windows XP 64-Bit, Windows Server 2003 Enterprise, and Windows Server 2003 Datacenter support Intel's IA-64 processors. As of April 25 2005 Microsoft had released four editions for 'x64' (AMD64 or EM64T): Windows XP Professional x64 Edition, Windows Server 2003 Standard x64 Edition, Windows Server 2003 Enterprise x64 Edition, and Windows Server 2003 Datacenter x64 Edition.
The Xbox uses a heavily modified and stripped-down Windows 2000 kernel. This kernel was heavily modified again for the Xbox 360, which runs on PowerPC. This version is not for separate sale, and little is known about it.
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 current Draft Revision 0.8 (March 10 2006)[1] requires 512 MB of main memory for 6.0, an 8-fold increase on the previous release. No specifications for processors or free disk space have been published for Vista at the time of writing.
| NT Version | CPU | RAM | Disk space |
|---|---|---|---|
| NT Workstation 3.51 | 386, 25 MHz | 8 MB | 90 MB |
| NT 4.0 Workstation | 486, 33 MHz | 12 MB | 110 MB |
| 2000 Professional | Pentium, 133 MHz | 32 MB | 650 MB |
| XP Professional | Pentium MMX, 233 MHz | 64 MB | 1.5 GB |
| Vista | Pentium III, 800 MHz (Home Basic)
1GHz (other editions) |
512 MB (Home Basic)
1GB (other editions) |
15 GB (Home Basic)
40GB (other editions) |
| 7 | 1 GHz | 1GB (32-bit)
2GB (64-bit) |
16GB (32-bit)
20GB (64-bit) |
| 8 | 1 GHz with NX bit, SSE2, PAE | 1GB (32-bit)
2GB (64-bit) |
16GB (32-bit)
20GB (64-bit) |
| 8.1 | 1 GHz with NX bit, SSE2, PAE | 1GB (32-bit)
2GB (64-bit) |
16GB (32-bit)
20GB (64-bit) |
| 10 | 1 GHz with NX bit, SSE2, PAE | 1GB (32-bit)
2GB (64-bit) |
16GB (32-bit)
20GB (64-bit) |
'NT' designation
It is popularly believed that Dave Cutler intended the initialism 'WNT' as a pun on VMS, incrementing each letter by one, similar to the apocryphal story of Arthur C. Clarke deriving HAL 9000's name by decrementing each letter of IBM. While this would have suited Cutler's sense of humor, the project's earlier name of NT OS/2 belies this theory. Another of the original OS/2 3.0 developers, Mark Lucovsky, states that the name was taken from the Intel i860 processor—code-named 'N-Ten'—which served as the original target hardware. Various Microsoft publications, including a 1998 question-and-answer session with Bill Gates, reveal that the letters were expanded to 'New Technology' for marketing purposes but no longer carry any specific meaning.
The letters were dropped from the name of Windows 2000, though the box contained the phrase 'Built on NT technology'. This action ostensibly reflected Microsoft's intent to unify its home and business lines, then represented by Windows 98 and Windows NT 4.0, but this goal would not be achieved until the introduction of Windows XP. Some believe this to be the result of a trademark dispute between Microsoft and Nortel as on the bottom of the Windows NT 4.0 product boxes is a notice explaining that 'NT' is a trademark of Northern Telecom.
See also
- Architecture of the Windows NT operating system line
- Microsoft Windows
- NT Domain
- ReactOS (an open source project with the goal of providing binary- and device driver-level compatibility with Windows NT)
- Windows Server System
- Windows NT Startup Process
External links
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