Windows NT

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Windows NT 3.5 Windows NT 3.51 Windows NT 4.0 Windows 2000 Windows XP Windows Server 2003 Windows XP Professional x64 Windows Vista Windows Server 2008 Windows 7 Windows Server 2008 R2 Windows 8 Windows Phone 8 Windows RT Windows Server 2012

Windows NT ( Windows New Technology for short ) is the name for a group of operating systems of the company Microsoft. Since its version 5.0, Windows NT is no longer used as part of the product name, but only as an internal version shortcuts.


The development of Windows NT began when the alliance between IBM and Microsoft for production of OS / 2 broke.

Responsible Head

Head of the NT project was David N. Cutler. He was considered one of the most reputable developers of operating systems at all and had been instrumental in the development of the VMS operating system, which is why the Windows NT kernel has many similarities with VMS. Microsoft began recruiting him and members of his team of DEC and put them on the development of a new operating system. This solicitation answered DEC with a lawsuit that Microsoft was able to settle by paying $ 150 million and the commitment to support Windows NT and Alpha processors.


Cutler sat two main objectives for Windows NT. His concern was to achieve reliability - a crashing application should not be able to bring the entire system to crash. This stability was already common among operating systems such as VMS or Unix-like systems. Also important was portability - Windows NT should be able to run on all modern computer architectures. It should also Windows NT, similar to how it could have the Mach kernel, the same time serve as a basis for various operating systems and as such as Windows, MS -DOS, OS/2- and POSIX programs can run simultaneously. The working title during development was therefore also Portasys.


According to the former Microsoft employee Mark Lucovsky NT originally stood for N- Ten. This was the code name for the Intel i860 processor under development. It was intended as a platform for NT, but was not present at Microsoft. Therefore has been developed on an emulator. For marketing purposes, the abbreviation was later reinterpreted in New Technology.

The first shipping version had the version number 3.1. Thus, a reference to Windows should be made ​​3.1, which had the same graphical user interface and the appearance of Windows NT represented the currently available on the market DOS-based version of Windows.

After Windows NT 4.0, NT abbreviation and the version number in the fall product names were left. The successor versions are called 2012 Windows 2000, Windows XP, Windows Server 2003, Windows Vista, Windows Server 2008 ( and R2 ), Windows 7, Windows 8 and Windows Server. All give the environment variable OS operating system as Windows_NT. Windows 2000 still has the home screen with the text " on NT technology based " attention to the relationship.

Architecture and subsystems

Cutler had achieved its two primary objectives: The new operating system was stable (MIPS and x86, PowerPC and Alpha later ) was due to its modular development on multiple platforms and offered different types of program support. It ran both 16- bit Windows 3.x programs as well as programs for the new 32- bit Windows NT API and text-based OS/2-Software and POSIX -1.0- compatible programs. Over the years a return or further development took place here but instead again. The OS/2- and POSIX versions were initially not maintained and later removed. The versions for PowerPC, MIPS, and Alpha was set, but were added later IA -64 and x64 versions of Windows and with RT also an ARM version, the latter being the version of Win32 applications that have not been signed by Microsoft, no longer supported.

In the first NT versions GDI runs together with the other subsystems on the ring 3 of the Intel privilege level outside the kernel range. Thus, the kernel itself is protected against falls in the programs. From NT 4.0, the graphics subsystem for reasons of speed runs partly directly in the kernel, making errors in graphics drivers can bring modern Windows NT versions to crash. Windows Vista uses the new graphics driver model, however, again userspace driver.

Windows NT has a modular construction. The lowest level is the hardware abstraction layer ( engl. Hardware Abstraction Layer, abbreviated HAL). Then build the kernel has to (a hybrid kernel) and subsystems. The kernel handles the allocation of memory and computation time. The kernel subsystems rely on. The Win32 subsystem is thereby the greatest importance, since it also takes care of the structure of the graphical user interface and processes the signals from the input devices. In the Enterprise and Ultimate editions of Windows Vista, Microsoft Windows Services for UNIX are included in the form of a POSIX -compatible subsystem for UNIX-based applications.

Due to compatibility and performance reasons, especially for games, Microsoft developed the DOS-based operating system line Windows NT 3.x/9x next to continue first. Only with the advent of Windows XP, the DOS-based line was abandoned, with Windows XP ( as the forerunner Windows 2000) has a pure NT kernel.

Support for new techniques

Already the first Windows NT version was completely detached from MS -DOS. For backward compatibility, however, older 16 -bit DOS programs such as the MS -DOS command line interpreter could be run in a Virtual DOS Machine. Programs (ie without the subsystem of Windows) to access the hardware directly, are not performed for safety reasons. In addition, the user was an advanced, fully 32- bit -capable command line interpreter named cmd.exe available. In addition, Windows NT supported in version 3.1, the file system is NTFS (New Technology File System) and has always had a 32- bit kernel.

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