History of Microsoft Windows
In 1983, Microsoft announced the development of Windows, a graphical user interface (GUI) for its own operating system (MS-DOS), which had shipped for IBM PC and compatible computers since 1981. The product line has changed from a GUI product to a modern operating system over two families of design, each with its own codebase and default file system.
The 3.x and 4.x family includes MS-DOS, Windows 95, Windows 98, and Windows Me. The DOS-based Windows for Workgroups 3.11 achieved the breakthrough from 16- to 32-bit networking and 32-bit disk access. The notable change with Windows 95 was from Program Manager to Explorer, but several os-components were rewritten and/or recompiled into 32-bit code for Windows 95.
Windows NT family started with NT 3.1 in 1993. Modern Windows operating system versions are based on the newer Windows NT kernel that was originally intended for OS/2. Windows runs on IA-32, x86-64, and Itanium processors. Earlier versions also ran on the Alpha, MIPS, Fairchild Clipper, and PowerPC architectures. Some work was done to port it to the SPARC architecture. The NT kernel borrows many techniques from VMS. With NT4.0 in 1996 the shell changed from Program Manager to Explorer. CPU support included PowerPC, MIPS, and DEC Alpha for earlier versions of NT, but focuses on Itanium, 386, 486, and x64 today.
