Windows NT
Encyclopedia
Windows NT is a family of operating system
s produced by Microsoft
, the first version of which was released in July 1993. It was a powerful high-level-language-based, processor-independent, multiprocessing, multiuser operating system with features comparable to Unix
. It was intended to complement consumer versions of Windows that were based on MS-DOS
. NT was the first fully 32-bit version of Windows, whereas its consumer-oriented counterparts, Windows 3.1x
and Windows 9x
, were 16-bit/32-bit hybrids. Windows 2000
, Windows XP
, Windows Server 2003
, Windows Vista
, Windows Home Server
, Windows Server 2008, and Windows 7 are effectively Windows NT, although they are not branded using that name.
It is popularly believed that Dave Cutler
intended the initialism 'WNT' as a pun on VMS, incrementing each letter by one
. However, the project was named NT OS/2 before receiving the Windows brand. One of the original OS/2 3.0 developers, Mark Lucovsky
, states that the name was taken from the original target processor—the Intel i860
, code-named N10 ('N-Ten'). 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 Microsoft described the product as 'Built on NT technology.'
, MIPS
R3000/R4000, and Alpha
, with PowerPC
, Itanium
, AMD64
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 after NT 4.0. Broad software compatibility was achieved with support for several API
"personalities", including Win32, POSIX
, and OS/2
APIs - the latter two were phased out starting with Windows XP. Partial MS-DOS
compatibility was achieved via an integrated DOS Virtual Machine - although this feature is being phased out in the x86-64
architecture. NT supported per-object (file, function, and role) access control list
s 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 STREAMS
, then later rewritten in-house.)
Windows NT 3.1 was the first version of Windows to utilize 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, 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 integrated into the kernel. 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 Start Menu
/Taskbar
design.
NTFS
, a journaled, secure file system, was created for NT. Windows NT also allows for other installable file systems, and with versions 3.1 and 3.51, NT could also be installed on DOS's FAT
or OS/2's HPFS file systems. Later versions could be installed on a FAT32 partition, in select cases, including Vista versions. Windows Vista and Windows 7 require a FAT32 partition to boot on an EFI
based system.
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 i860
XR 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 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 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, 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.
, 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
.
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. There were also some issues related to Novell IPX protocol licensing, which was apparently limited 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. The build number is an internal identifier used by Microsoft's developers and beta testers.
, and is reasonably portable, although 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.
-based Dazzle system and, later, the MIPS R4000-based Jazz
platform. Both systems were designed internally at Microsoft.
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, 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).
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
.
According to Microsoft, it is a common misconception that the Xbox
and Xbox 360
use a modified Windows 2000 kernel. They claim that the Xbox operating system was built from scratch but implements a subset of Windows API
s. The idea that it does, indeed, run a modified copy of the Windows kernel still persists in the community.
as well as on Alpha. Alpha hardware was accordingly used internally at Microsoft during early development of 64-bit Windows. This continued for some time after Microsoft publicly announced that it was cancelling plans to ship 64-bit Windows for Alpha, because Itanium hardware was not yet available for development.
, Microsoft has released seven editions for Itanium and seventeen editions for the x64
processor architecture:
* Windows XP can be run at 64 MB RAM. Some features require 128 MB RAM.
** Windows Vista and 7 can be run from 512 MB but Microsoft recommends 1 GB.
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
s produced by Microsoft
Microsoft
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
, the first version of which was released in July 1993. It was a powerful high-level-language-based, processor-independent, multiprocessing, multiuser operating system with features comparable to Unix
Unix
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
. It was intended to complement consumer versions of Windows that were based on MS-DOS
MS-DOS
MS-DOS is an operating system for x86-based personal computers. It was the most commonly used member of the DOS family of operating systems, and was the main operating system for IBM PC compatible personal computers during the 1980s to the mid 1990s, until it was gradually superseded by operating...
. NT was the first fully 32-bit version of Windows, whereas its consumer-oriented counterparts, Windows 3.1x
Windows 3.1x
Windows 3.1x is a series of 16-bit operating systems produced by Microsoft for use on personal computers. The series began with Windows 3.1, which was first sold during March 1992 as a successor to Windows 3.0...
and Windows 9x
Windows 9x
Windows 9x is a generic term referring to a series of Microsoft Windows computer operating systems produced since 1995, which were based on the original and later modified Windows 95 kernel...
, were 16-bit/32-bit hybrids. Windows 2000
Windows 2000
Windows 2000 is a line of operating systems produced by Microsoft for use on personal computers, business desktops, laptops, and servers. Windows 2000 was released to manufacturing on 15 December 1999 and launched to retail on 17 February 2000. It is the successor to Windows NT 4.0, and is the...
, Windows XP
Windows XP
Windows XP is an operating system produced by Microsoft for use on personal computers, including home and business desktops, laptops and media centers. First released to computer manufacturers on August 24, 2001, it is the second most popular version of Windows, based on installed user base...
, Windows Server 2003
Windows Server 2003
Windows Server 2003 is a server operating system produced by Microsoft, introduced on 24 April 2003. An updated version, Windows Server 2003 R2, was released to manufacturing on 6 December 2005...
, Windows Vista
Windows Vista
Windows Vista is an operating system released in several variations developed by Microsoft for use on personal computers, including home and business desktops, laptops, tablet PCs, and media center PCs...
, Windows Home Server
Windows Home Server
Windows Home Server, code-named Quattro, is a home server operating system from Microsoft. Announced on 7 January 2007, at the Consumer Electronics Show by Bill Gates, Windows Home Server is intended to be a solution for homes with multiple connected PCs to offer file sharing, automated backups,...
, Windows Server 2008, and Windows 7 are effectively Windows NT, although they are not branded using that name.
It is popularly believed that Dave Cutler
Dave Cutler
David Neil Cutler, Sr. is an American software engineer, designer and developer of several operating systems including RSX-11M, VMS and VAXELN at Digital Equipment Corporation and Windows at Microsoft.- Personal history :...
intended the initialism 'WNT' as a pun on VMS, incrementing each letter by one
Caesar cipher
In cryptography, a Caesar cipher, also known as a Caesar's cipher, the shift cipher, Caesar's code or Caesar shift, is one of the simplest and most widely known encryption techniques. It is a type of substitution cipher in which each letter in the plaintext is replaced by a letter some fixed number...
. However, the project was named NT OS/2 before receiving the Windows brand. One of the original OS/2 3.0 developers, Mark Lucovsky
Mark Lucovsky
Mark Lucovsky is an American software developer who worked for Microsoft and who is now employed by VMware as Vice President of Engineering in charge of Cloud Foundry...
, states that the name was taken from the original target processor—the Intel i860
Intel i860
The Intel i860 was a RISC microprocessor from Intel, first released in 1989. The i860 was one of Intel's first attempts at an entirely new, high-end instruction set since the failed Intel i432 from the 1980s...
, code-named N10 ('N-Ten'). Various Microsoft publications, including a 1998 question-and-answer session with Bill Gates
Bill Gates
William Henry "Bill" Gates III is an American business magnate, investor, philanthropist, and author. Gates is the former CEO and current chairman of Microsoft, the software company he founded with Paul Allen...
, reveal that the letters were expanded
Backronym
A backronym or bacronym is a phrase constructed purposely, such that an acronym can be formed to a specific desired word. Backronyms may be invented with serious or humorous intent, or may be a type of false or folk etymology....
to 'New Technology' for marketing purposes but no longer carry any specific meaning. The letters were dropped from the name of Windows 2000, though Microsoft described the product as 'Built on NT technology.'
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 Intel IA-32IA-32
IA-32 , also known as x86-32, i386 or x86, is the CISC instruction-set architecture of Intel's most commercially successful microprocessors, and was first implemented in the Intel 80386 as a 32-bit extension of x86 architecture...
, MIPS
MIPS architecture
MIPS is a reduced instruction set computer instruction set architecture developed by MIPS Technologies . The early MIPS architectures were 32-bit, and later versions were 64-bit...
R3000/R4000, and Alpha
DEC Alpha
Alpha, originally known as Alpha AXP, is a 64-bit reduced instruction set computer instruction set architecture developed by Digital Equipment Corporation , designed to replace the 32-bit VAX complex instruction set computer ISA and its implementations. Alpha was implemented in microprocessors...
, with PowerPC
PowerPC
PowerPC is a RISC architecture created by the 1991 Apple–IBM–Motorola alliance, known as AIM...
, Itanium
Itanium
Itanium is a family of 64-bit Intel microprocessors that implement the Intel Itanium architecture . Intel markets the processors for enterprise servers and high-performance computing systems...
, AMD64
X86-64
x86-64 is an extension of the x86 instruction set. It supports vastly larger virtual and physical address spaces than are possible on x86, thereby allowing programmers to conveniently work with much larger data sets. x86-64 also provides 64-bit general purpose registers and numerous other...
and ARM
ARM architecture
ARM is a 32-bit reduced instruction set computer instruction set architecture developed by ARM Holdings. It was named the Advanced RISC Machine, and before that, the Acorn RISC Machine. The ARM architecture is the most widely used 32-bit ISA in numbers produced...
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 after NT 4.0. Broad software compatibility was achieved with support for several API
Application programming interface
An application programming interface is a source code based specification intended to be used as an interface by software components to communicate with each other...
"personalities", including Win32, POSIX
Microsoft POSIX subsystem
Microsoft POSIX subsystem is one of 3 subsystems of several operating systems from the Windows NT family ....
, and OS/2
OS/2
OS/2 is a computer operating system, initially created by Microsoft and IBM, then later developed by IBM exclusively. The name stands for "Operating System/2," because it was introduced as part of the same generation change release as IBM's "Personal System/2 " line of second-generation personal...
APIs - the latter two were phased out starting with Windows XP. Partial MS-DOS
MS-DOS
MS-DOS is an operating system for x86-based personal computers. It was the most commonly used member of the DOS family of operating systems, and was the main operating system for IBM PC compatible personal computers during the 1980s to the mid 1990s, until it was gradually superseded by operating...
compatibility was achieved via an integrated DOS Virtual Machine - although this feature is being phased out in the x86-64
X86-64
x86-64 is an extension of the x86 instruction set. It supports vastly larger virtual and physical address spaces than are possible on x86, thereby allowing programmers to conveniently work with much larger data sets. x86-64 also provides 64-bit general purpose registers and numerous other...
architecture. NT supported per-object (file, function, and role) access control list
Access control list
An access control list , with respect to a computer file system, is a list of permissions attached to an object. An ACL specifies which users or system processes are granted access to objects, as well as what operations are allowed on given objects. Each entry in a typical ACL specifies a subject...
s 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
LAN Manager
LAN Manager was a Network Operating System available from multiple vendors and developed by Microsoft in cooperation with 3Com Corporation. It was designed to succeed 3Com's 3+Share network server software which ran atop a heavily modified version of MS-DOS.-Development history:LAN Manager was...
networking, as well as TCP/IP networking (for which Microsoft would implement a TCP/IP stack derived at first from STREAMS
STREAMS
In computer networking, STREAMS is the native framework in Unix System V for implementing character devices.STREAMS was designed as a modular architecture for implementing full-duplex I/O between kernel or user space processes and device drivers. Its most frequent uses have been in developing...
, then later rewritten in-house.)
Windows NT 3.1 was the first version of Windows to utilize 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, 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
User space
A conventional computer operating system usually segregates virtual memory into kernel space and user space. Kernel space is strictly reserved for running the kernel, kernel extensions, and most device drivers...
subsystems. In Windows NT 4, the video, server, and printer spooler subsystems were integrated into the kernel. Windows NT's first GUI
Graphical user interface
In computing, a graphical user interface is a type of user interface that allows users to interact with electronic devices with images rather than text commands. GUIs can be used in computers, hand-held devices such as MP3 players, portable media players or gaming devices, household appliances and...
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
Windows 95
Windows 95 is a consumer-oriented graphical user interface-based operating system. It was released on August 24, 1995 by Microsoft, and was a significant progression from the company's previous Windows products...
, moving from the Program Manager
Program Manager
Program Manager is the shell of Windows 3.x and Windows NT 3.x operating systems. This shell exposed a task-oriented graphical user interface , consisting of icons arranged into program groups. It replaced MS-DOS Executive, a file manager, as the default Windows shell.The program derives from the...
to the Start Menu
Start menu
The Start Menu and Start Button are user interface elements used in the later versions of the Microsoft Windows operating systems and in some X window managers...
/Taskbar
Taskbar
In computing, a taskbar is a bar displayed on a full edge of a GUI desktop that is used to launch and monitor running applications. Microsoft incorporated a taskbar in Windows 95 and it has been a defining aspect of Microsoft Windows's graphical user interface ever since. Some desktop environments,...
design.
NTFS
NTFS
NTFS is the standard file system of Windows NT, including its later versions Windows 2000, Windows XP, Windows Server 2003, Windows Server 2008, Windows Vista, and Windows 7....
, a journaled, secure file system, was created for NT. Windows NT also allows for other installable file systems, and with versions 3.1 and 3.51, NT could also be installed on DOS's FAT
File Allocation Table
File Allocation Table is a computer file system architecture now widely used on many computer systems and most memory cards, such as those used with digital cameras. FAT file systems are commonly found on floppy disks, flash memory cards, digital cameras, and many other portable devices because of...
or OS/2's HPFS file systems. Later versions could be installed on a FAT32 partition, in select cases, including Vista versions. Windows Vista and Windows 7 require a FAT32 partition to boot on an EFI
Extensible Firmware Interface
The Unified Extensible Firmware Interface is a specification that defines a software interface between an operating system and platform firmware...
based system.
Development
Microsoft decided to create a portable operating system, compatible with OS/2OS/2
OS/2 is a computer operating system, initially created by Microsoft and IBM, then later developed by IBM exclusively. The name stands for "Operating System/2," because it was introduced as part of the same generation change release as IBM's "Personal System/2 " line of second-generation personal...
and POSIX
Microsoft POSIX subsystem
Microsoft POSIX subsystem is one of 3 subsystems of several operating systems from the Windows NT family ....
and supporting multiprocessing
Multiprocessing
Multiprocessing is the use of two or more central processing units within a single computer system. The term also refers to the ability of a system to support more than one processor and/or the ability to allocate tasks between them...
, in October 1988. When development started in November 1989, Windows NT was to be known as OS/2
OS/2
OS/2 is a computer operating system, initially created by Microsoft and IBM, then later developed by IBM exclusively. The name stands for "Operating System/2," because it was introduced as part of the same generation change release as IBM's "Personal System/2 " line of second-generation personal...
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 i860
Intel i860
The Intel i860 was a RISC microprocessor from Intel, first released in 1989. The i860 was one of Intel's first attempts at an entirely new, high-end instruction set since the failed Intel i432 from the 1980s...
XR RISC processor, switching to the MIPS
MIPS architecture
MIPS is a reduced instruction set computer instruction set architecture developed by MIPS Technologies . The early MIPS architectures were 32-bit, and later versions were 64-bit...
R3000
R3000
The R3000 is a microprocessor chip set developed by MIPS Computer Systems that implemented the MIPS I instruction set architecture . Introduced in June 1988, it was the second MIPS implementation, succeeding the R2000 as the flagship MIPS microprocessor...
in late 1989, and then the Intel i386 in 1990. Microsoft also continued parallel development of the DOS-based and less resource
Resource (computer science)
A resource, or system resource, is any physical or virtual component of limited availability within a computer system. Every device connected to a computer system is a resource. Every internal system component is a resource...
-demanding Windows environment, resulting in the release of Windows 3.0
Windows 3.0
Windows 3.0, a graphical environment, is the third major release of Microsoft Windows, and was released on 22 May 1990. It became the first widely successful version of Windows and a rival to Apple Macintosh and the Commodore Amiga on the GUI front...
in May 1990. Windows 3 was eventually so successful that Microsoft decided to change the primary application programming interface
Application programming interface
An application programming interface is a source code based specification intended to be used as an interface by software components to communicate with each other...
for the still unreleased NT OS/2 (as it was then known) from an extended OS/2 API to an extended Windows API
Windows API
The Windows API, informally WinAPI, is Microsoft's core set of application programming interfaces available in the Microsoft Windows operating systems. It was formerly called the Win32 API; however, the name "Windows API" more accurately reflects its roots in 16-bit Windows and its support on...
. 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
Digital Equipment Corporation
Digital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...
led by Dave Cutler
Dave Cutler
David Neil Cutler, Sr. is an American software engineer, designer and developer of several operating systems including RSX-11M, VMS and VAXELN at Digital Equipment Corporation and Windows at Microsoft.- Personal history :...
to build Windows NT, and many elements of the design reflect earlier DEC experience with Cutler's VMS and RSX-11
RSX-11
RSX-11 is a family of real-time operating systems mainly for PDP-11 computers created by Digital Equipment Corporation , common in the late 1970s and early 1980s. RSX-11D first appeared on the PDP-11/40 in 1972...
. 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
Microkernel
In computer science, a microkernel is the near-minimum amount of software that can provide the mechanisms needed to implement an operating system . These mechanisms include low-level address space management, thread management, and inter-process communication...
, as the Windows NT kernel was influenced by the Mach microkernel
Mach (kernel)
Mach is an operating system kernel developed at Carnegie Mellon University to support operating system research, primarily distributed and parallel computation. Although Mach is often mentioned as one of the earliest examples of a microkernel, not all versions of Mach are microkernels...
developed at Carnegie Mellon University, 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
Native API
The Native API is the publicly- and incompletely-documented application programming interface used internally by the Windows NT family of operating systems produced by Microsoft.. It is predominately used during system boot, when other components of Windows are unavailable. The Program Entry point...
; 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
Unicode
Unicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems...
internally.
Driver models
Windows NT introduced its own driver model, the Windows NT driver model, and is incompatible with older driver frameworks. With Windows 2000Windows 2000
Windows 2000 is a line of operating systems produced by Microsoft for use on personal computers, business desktops, laptops, and servers. Windows 2000 was released to manufacturing on 15 December 1999 and launched to retail on 17 February 2000. It is the successor to Windows NT 4.0, and is the...
, the Windows NT driver model was enhanced to become the Windows Driver Model
Windows Driver Model
In computing, the Windows Driver Model — also known at one point as the Win32 Driver Model — is a framework for device drivers that was introduced with Windows 98 and Windows 2000 to replace VxD, which was used on older versions of Windows such as Windows 95 and Windows 3.1, as well...
, which was first introduced with Windows 98
Windows 98
Windows 98 is a graphical operating system by Microsoft. It is the second major release in the Windows 9x line of operating systems. It was released to manufacturing on 15 May 1998 and to retail on 25 June 1998. Windows 98 is the successor to Windows 95. Like its predecessor, it is a hybrid...
, but was based on the NT driver model. Windows Vista
Windows Vista
Windows Vista is an operating system released in several variations developed by Microsoft for use on personal computers, including home and business desktops, laptops, tablet PCs, and media center PCs...
added native support for the Windows Driver Foundation
Windows Driver Foundation
Windows Driver Foundation is a set of Microsoft tools that aid in the creation of device drivers for Windows 2000 and later versions of Windows....
, which is also available for Windows XP
Windows XP
Windows XP is an operating system produced by Microsoft for use on personal computers, including home and business desktops, laptops and media centers. First released to computer manufacturers on August 24, 2001, it is the second most popular version of Windows, based on installed user base...
, Windows Server 2003
Windows Server 2003
Windows Server 2003 is a server operating system produced by Microsoft, introduced on 24 April 2003. An updated version, Windows Server 2003 R2, was released to manufacturing on 6 December 2005...
and to an extent, Windows 2000
Windows 2000
Windows 2000 is a line of operating systems produced by Microsoft for use on personal computers, business desktops, laptops, and servers. Windows 2000 was released to manufacturing on 15 December 1999 and launched to retail on 17 February 2000. It is the successor to Windows NT 4.0, and is the...
.
Releases
| Version | Marketing name | Editions | Release date | RTM build |
|---|---|---|---|---|
| NT 3.1 | Windows NT 3.1 Windows NT 3.1 Windows NT 3.1 is the first release of Microsoft's Windows NT line of server and business desktop operating systems, and was released to manufacturing on 27 July 1993. The version number was chosen to match the one of Windows 3.1, the then-latest operating environment from Microsoft, on account of... |
Workstation (named just Windows NT), Advanced Server | 27 July 1993 | 528 |
| NT 3.5 | Windows NT 3.5 Windows NT 3.5 Windows NT 3.5 is the second release of the Microsoft Windows NT operating system. It was released on 21 September 1994.One of the primary goals during Windows NT 3.5's development was to increase the speed of the operating system; as a result, the project was given the codename "Daytona" in... |
Workstation Workstation A workstation is a high-end microcomputer designed for technical or scientific applications. Intended primarily to be used by one person at a time, they are commonly connected to a local area network and run multi-user operating systems... , Server |
21 September 1994 | 807 |
| NT 3.51 | Windows NT 3.51 Windows NT 3.51 Windows NT 3.51 is the third release of Microsoft's Windows NT line of operating systems. It was released on 30 May 1995, nine months after Windows NT 3.5. The release provided two notable feature improvements; firstly NT 3.51 was the first of a short-lived outing of Microsoft Windows on the... |
Workstation, Server | 30 May 1995 | 1057 |
| NT 4.0 | Windows NT 4.0 Windows NT 4.0 Windows NT 4.0 is a preemptive, graphical and business-oriented operating system designed to work with either uniprocessor or symmetric multi-processor computers. It was the next release of Microsoft's Windows NT line of operating systems and was released to manufacturing on 31 July 1996... |
Workstation, Server, Server Enterprise Edition, Terminal Server, Embedded | 29 July 1996 | 1381 |
| NT 5.0 | Windows 2000 Windows 2000 Windows 2000 is a line of operating systems produced by Microsoft for use on personal computers, business desktops, laptops, and servers. Windows 2000 was released to manufacturing on 15 December 1999 and launched to retail on 17 February 2000. It is the successor to Windows NT 4.0, and is the... |
Professional, Server, Advanced Server, Datacenter Server, Advanced/Datacenter Server Limited Edition | 17 February 2000 | 2195 |
| NT 5.1 | Windows XP Windows XP Windows XP is an operating system produced by Microsoft for use on personal computers, including home and business desktops, laptops and media centers. First released to computer manufacturers on August 24, 2001, it is the second most popular version of Windows, based on installed user base... |
Home, Professional, 64-bit Edition, Media Center Windows XP Media Center Edition Windows XP Media Center Edition is a version of the Windows XP operating system designed to serve as a home-entertainment hub. The last version, Windows XP Media Center Edition 2005, was released in October 2004.-Versions:... (original, 2003, 2004 & 2005), Tablet PC (original and 2005), Starter, Embedded, Home N, Professional N |
25 October 2001 | 2600 |
| NT 5.1 | Windows Fundamentals for Legacy PCs Windows Fundamentals for Legacy PCs Windows Fundamentals for Legacy PCs is a thin client operating system from Microsoft, based on Windows XP Embedded, but optimized for older, less powerful hardware. It was released on 8 July 2006... |
8 July 2006 | 2600 | |
| NT 5.2 | Windows XP Windows XP Windows XP is an operating system produced by Microsoft for use on personal computers, including home and business desktops, laptops and media centers. First released to computer manufacturers on August 24, 2001, it is the second most popular version of Windows, based on installed user base... |
64-bit Edition Version 2003 | 28 March 2003 | 3790 |
| NT 5.2 | Windows Server 2003 Windows Server 2003 Windows Server 2003 is a server operating system produced by Microsoft, introduced on 24 April 2003. An updated version, Windows Server 2003 R2, was released to manufacturing on 6 December 2005... |
Standard, Enterprise, Datacenter, Web, Storage, Small Business Server, Compute Cluster | 24 April 2003 | 3790 |
| NT 5.2 | Windows XP Windows XP Windows XP is an operating system produced by Microsoft for use on personal computers, including home and business desktops, laptops and media centers. First released to computer manufacturers on August 24, 2001, it is the second most popular version of Windows, based on installed user base... |
Professional x64 Edition Windows XP Professional x64 Edition Microsoft Windows XP Professional x64 Edition released on April 25, 2005 is an edition of Windows XP for x86-64 personal computers. It is designed to use the expanded 64-bit memory address space provided by the x86-64 architecture.... |
25 April 2005 | 3790 |
| NT 5.2 | Windows Server 2003 R2 | Standard, Enterprise, Datacenter, Web, Storage, Small Business Server, Compute Cluster | 6 December 2005 | 3790 |
| NT 5.2 | Windows Home Server Windows Home Server Windows Home Server, code-named Quattro, is a home server operating system from Microsoft. Announced on 7 January 2007, at the Consumer Electronics Show by Bill Gates, Windows Home Server is intended to be a solution for homes with multiple connected PCs to offer file sharing, automated backups,... |
16 July 2007 | 3790 | |
| NT 6.0 | Windows Vista Windows Vista Windows Vista is an operating system released in several variations developed by Microsoft for use on personal computers, including home and business desktops, laptops, tablet PCs, and media center PCs... |
Starter, Home Basic, Home Premium, Business, Enterprise, Ultimate, Home Basic N, Business N | Business: 30 November 2006 Consumer: 30 January 2007 |
6000 6001(SP1) 6002(SP2) |
| NT 6.0 | Windows Server 2008 | Foundation, Standard, Enterprise, Datacenter, Web Server, HPC Server, Itanium-Based Systems | 27 February 2008 | 6001 6002(SP2) |
| NT 6.1 | Windows 7 | Starter, Home Basic, Home Premium, Professional, Enterprise, Ultimate | 22 October 2009 | 7600 7601(SP1) |
| NT 6.1 | Windows Server 2008 R2 Windows Server 2008 R2 Windows Server 2008 R2 is a server operating system produced by Microsoft. It was released to manufacturing on July 22, 2009 and launched on October 22, 2009. According to the Windows Server Team blog, the retail availability was September 14, 2009. It is built on Windows NT 6.1, the same core... |
Foundation, Standard, Enterprise, Datacenter, Web Server, HPC Server, Itanium-Based Systems | 22 October 2009 | 7600 7601(SP1) |
| NT 6.2 | Windows 8 Windows 8 Windows 8 is the codename for the next version of the Microsoft Windows computer operating system following Windows 7. It has many changes from previous versions. In particular it adds support for ARM microprocessors in addition to the previously supported x86 microprocessors from Intel and AMD... |
TBA | TBA | TBA |
| TBA | Windows Server 8 | TBA | TBA | TBA |
Windows NT 3.1 to 3.51 incorporated the Program Manager
Program Manager
Program Manager is the shell of Windows 3.x and Windows NT 3.x operating systems. This shell exposed a task-oriented graphical user interface , consisting of icons arranged into program groups. It replaced MS-DOS Executive, a file manager, as the default Windows shell.The program derives from the...
and File Manager from the Windows 3.x
Windows 3.x
Windows 3.x can refer to either an individual or all of the following versions of Microsoft Windows:*Windows 3.0*Windows 3.1x*Windows 3.2...
series. Windows NT 4.0 onwards replaced those programs with Windows Explorer
Windows Explorer
This article is about the Windows file system browser. For the similarly named web browser, see Internet ExplorerWindows Explorer is a file manager application that is included with releases of the Microsoft Windows operating system from Windows 95 onwards. It provides a graphical user interface...
(including a taskbar
Taskbar
In computing, a taskbar is a bar displayed on a full edge of a GUI desktop that is used to launch and monitor running applications. Microsoft incorporated a taskbar in Windows 95 and it has been a defining aspect of Microsoft Windows's graphical user interface ever since. Some desktop environments,...
and Start menu
Start menu
The Start Menu and Start Button are user interface elements used in the later versions of the Microsoft Windows operating systems and in some X window managers...
), which originally appeared in Windows 95
Windows 95
Windows 95 is a consumer-oriented graphical user interface-based operating system. It was released on August 24, 1995 by Microsoft, and was a significant progression from the company's previous Windows products...
.
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. There were also some issues related to Novell IPX protocol licensing, which was apparently limited 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. The build number is an internal identifier used by Microsoft's developers and beta testers.
Supported platforms
NT was written in C and C++C++
C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features. It was developed by Bjarne Stroustrup starting in 1979 at Bell...
, and is reasonably portable, although only three architectures are currently supported. That said, it proved far more difficult to port applications such as Microsoft Office
Microsoft Office
Microsoft Office is a non-free commercial office suite of inter-related desktop applications, servers and services for the Microsoft Windows and Mac OS X operating systems, introduced by Microsoft in August 1, 1989. Initially a marketing term for a bundled set of applications, the first version of...
which were sensitive to issues such as data structure alignment
Data structure alignment
Data structure alignment is the way data is arranged and accessed in computer memory. It consists of two separate but related issues: data alignment and data structure padding. When a modern computer reads from or writes to a memory address, it will do this in word sized chunks...
on RISC processors. Unlike Windows CE
Windows CE
Microsoft Windows CE is an operating system developed by Microsoft for embedded systems. Windows CE is a distinct operating system and kernel, rather than a trimmed-down version of desktop Windows...
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 i860Intel i860
The Intel i860 was a RISC microprocessor from Intel, first released in 1989. The i860 was one of Intel's first attempts at an entirely new, high-end instruction set since the failed Intel i432 from the 1980s...
-based Dazzle system and, later, the MIPS R4000-based Jazz
Jazz (computer)
The Jazz computer architecture was a motherboard and chipset design originally developed by Microsoft for use in developing Windows NT. The design was eventually used as the basis for most MIPS-based Windows NT systems....
platform. Both systems were designed internally at Microsoft.
Windows NT 3.1 was released for Intel x86 PC compatible, DEC Alpha
DEC Alpha
Alpha, originally known as Alpha AXP, is a 64-bit reduced instruction set computer instruction set architecture developed by Digital Equipment Corporation , designed to replace the 32-bit VAX complex instruction set computer ISA and its implementations. Alpha was implemented in microprocessors...
, and ARC
Advanced RISC Computing
Advanced RISC Computing is a specification promulgated by a defunct consortium of computer manufacturers , setting forth a standard MIPS RISC-based computer hardware and firmware environment....
-compliant MIPS
MIPS architecture
MIPS is a reduced instruction set computer instruction set architecture developed by MIPS Technologies . The early MIPS architectures were 32-bit, and later versions were 64-bit...
platforms. Windows NT 3.51 added support for the PowerPC
PowerPC
PowerPC is a RISC architecture created by the 1991 Apple–IBM–Motorola alliance, known as AIM...
processor in 1995, specifically PReP
Prep
Prep may refer to:* A nickname for anything associated with a University-preparatory school, such as:** A member of the Preppy social group, stemming from the word "preparatory"** Another name for someone who attends a preparatory school in the US...
-compliant systems such as the IBM Power Series desktops/laptops and Motorola
Motorola
Motorola, Inc. was an American multinational telecommunications company based in Schaumburg, Illinois, which was eventually divided into two independent public companies, Motorola Mobility and Motorola Solutions on January 4, 2011, after losing $4.3 billion from 2007 to 2009...
PowerStack series; but despite meetings between Michael Spindler
Michael Spindler
Michael Spindler , nicknamed "the Diesel" for his reputed around-the-clock work habits, was president and CEO of Apple from 1993 to 1996....
and Bill Gates, not on the Power Macintosh
Power Macintosh
Power Macintosh, later Power Mac, was a line of Apple Macintosh workstation-class personal computers based on various models of PowerPC microprocessors that were developed, marketed, and supported by Apple Inc. from March 1994 until August 2006. The first models were the Power Macintosh 6100,...
as the PReP compliant Power Macintosh project failed to ship.
Intergraph Corporation ported Windows NT to its Clipper architecture
Clipper architecture
The Clipper architecture is a 32-bit RISC-like instruction set architecture designed by Fairchild Semiconductor. The architecture never enjoyed much market success, and the only computer manufacturers to create major product lines using Clipper processors were Intergraph and High Level Hardware...
and later announced intention to port Windows NT 3.51 to Sun Microsystems
Sun Microsystems
Sun Microsystems, Inc. was a company that sold :computers, computer components, :computer software, and :information technology services. Sun was founded on February 24, 1982...
' SPARC
SPARC
SPARC is a RISC instruction set architecture developed by Sun Microsystems and introduced in mid-1987....
architecture, 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
Compaq
Compaq Computer Corporation is a personal computer company founded in 1982. Once the largest supplier of personal computing systems in the world, Compaq existed as an independent corporation until 2002, when it was acquired for US$25 billion by Hewlett-Packard....
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).
Microsoft announced on 5 January 2011 that the next major version of the Windows NT family will include support for the ARM architecture
ARM architecture
ARM is a 32-bit reduced instruction set computer instruction set architecture developed by ARM Holdings. It was named the Advanced RISC Machine, and before that, the Acorn RISC Machine. The ARM architecture is the most widely used 32-bit ISA in numbers produced...
. Microsoft demonstrated a preliminary version of Windows (version 6.2.7867) running on an ARM-based computer at the 2011 Consumer Electronics Show
Consumer Electronics Show
The International Consumer Electronics Show is a major technology-related trade show held each January in the Las Vegas Convention Center, Las Vegas, Nevada, United States. Not open to the public, the Consumer Electronics Association-sponsored show typically hosts previews of products and new...
.
According to Microsoft, it is a common misconception that the Xbox
Xbox
The Xbox is a sixth-generation video game console manufactured by Microsoft. It was released on November 15, 2001 in North America, February 22, 2002 in Japan, and March 14, 2002 in Australia and Europe and is the predecessor to the Xbox 360. It was Microsoft's first foray into the gaming console...
and Xbox 360
Xbox 360
The Xbox 360 is the second video game console produced by Microsoft and the successor to the Xbox. The Xbox 360 competes with Sony's PlayStation 3 and Nintendo's Wii as part of the seventh generation of video game consoles...
use a modified Windows 2000 kernel. They claim that the Xbox operating system was built from scratch but implements a subset of Windows API
Windows API
The Windows API, informally WinAPI, is Microsoft's core set of application programming interfaces available in the Microsoft Windows operating systems. It was formerly called the Win32 API; however, the name "Windows API" more accurately reflects its roots in 16-bit Windows and its support on...
s. The idea that it does, indeed, run a modified copy of the Windows kernel still persists in the community.
64-bit platforms
Released versions of NT for Alpha were 32-bit only. The 64-bit port of Windows was originally intended to run on ItaniumItanium
Itanium is a family of 64-bit Intel microprocessors that implement the Intel Itanium architecture . Intel markets the processors for enterprise servers and high-performance computing systems...
as well as on Alpha. Alpha hardware was accordingly used internally at Microsoft during early development of 64-bit Windows. This continued for some time after Microsoft publicly announced that it was cancelling plans to ship 64-bit Windows for Alpha, because Itanium hardware was not yet available for development.
, Microsoft has released seven editions for Itanium and seventeen editions for the x64
X86-64
x86-64 is an extension of the x86 instruction set. It supports vastly larger virtual and physical address spaces than are possible on x86, thereby allowing programmers to conveniently work with much larger data sets. x86-64 also provides 64-bit general purpose registers and numerous other...
processor architecture:
| Itanium editions | x64 editions |
|---|---|
|
Windows XP Professional x64 Edition Microsoft Windows XP Professional x64 Edition released on April 25, 2005 is an edition of Windows XP for x86-64 personal computers. It is designed to use the expanded 64-bit memory address space provided by the x86-64 architecture.... |
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.| 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 |
| NT 3.51 Workstation NT 3.51 Server |
386, 25 MHz | 12 MB 16 MB |
90 MB |
| NT 4.0 Workstation NT 4.0 Server |
486, 25 MHz | 12 MB 16 MB |
124 MB |
| 2000 Professional 2000 Server |
Pentium, 133 MHz | 32 MB 128 MB |
650 MB |
| XP | Pentium, 233 MHz | 64 MB* | 1.5 GB |
| Server 2003 | Pentium, 133 MHz | 128 MB | 1.5 GB |
| Vista | Pentium III, 800 MHz | 512 MB** | 15 GB |
| 7 |
Pentium III, 1 GHz | 512 MB** | 16 GB |
See also
- Architecture of Windows NT
- Criticism of Microsoft WindowsCriticism of Microsoft WindowsThe various versions of Microsoft's desktop operating system, Windows, have received many criticisms since Microsoft's inception.-Clock management:Windows expects the real-time clock of the computer to run on local time...
- F6 diskF6 diskF6 disk is a colloquial name for a floppy disk containing a Microsoft Windows NT device driver for a SCSI or RAID system. F6 disks are used by all NT-based versions of Windows, including Windows 2000, Windows Server 2003, and Windows XP...
- Microsoft WindowsMicrosoft WindowsMicrosoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
- NT DomainWindows Server domainA Windows domain is a collection of security principals that share a central directory database. This central database contains the user accounts and security information for...
- NTFSNTFSNTFS is the standard file system of Windows NT, including its later versions Windows 2000, Windows XP, Windows Server 2003, Windows Server 2008, Windows Vista, and Windows 7....
- ReactOSReactOSReactOS is an open source computer operating system intended to be binary compatible with application software and device drivers made for Microsoft Windows NT versions 5.x and up...
(an open sourceOpen sourceThe term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
project with the goal of providing binary- and device driver-level compatibility with Windows NT) - Windows NT Startup ProcessWindows NT Startup ProcessThe Windows NT startup process is the process by which Windows NT 4.0, Windows 2000, Windows XP and Windows Server 2003 operating systems initialize...
- Windows Preinstallation EnvironmentWindows Preinstallation EnvironmentWindows Preinstallation Environment is a lightweight version of Windows XP, Windows Server 2003, Windows Vista, Windows 7, or Windows Server 2008 R2 that is used for the deployment of workstations and servers...
- Windows Server SystemWindows Server SystemMicrosoft Servers is a brand that encompasses a line of Microsoft server products. This includes the server editions of Microsoft Windows operating system itself, as well as products targeted at the wider business market...
- Windows EmbeddedWindows EmbeddedWindows Embedded is a family of operating systems from Microsoft designed for use in embedded systems. Microsoft makes available four different categories of operating systems for embedded devices targeting a wide market, ranging from small-footprint, real-time devices to Point of Sale devices like...