Development
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 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.
Read more about this topic: Windows NT
Famous quotes containing the word development:
“The development of civilization and industry in general has always shown itself so active in the destruction of forests that everything that has been done for their conservation and production is completely insignificant in comparison.”
—Karl Marx (1818–1883)
“For the child whose impulsiveness is indulged, who retains his primitive-discharge mechanisms, is not only an ill-behaved child but a child whose intellectual development is slowed down. No matter how well he is endowed intellectually, if direct action and immediate gratification are the guiding principles of his behavior, there will be less incentive to develop the higher mental processes, to reason, to employ the imagination creatively. . . .”
—Selma H. Fraiberg (20th century)
“Theories of child development and guidelines for parents are not cast in stone. They are constantly changing and adapting to new information and new pressures. There is no “right” way, just as there are no magic incantations that will always painlessly resolve a child’s problems.”
—Lawrence Kutner (20th century)