MS-DOS - Legacy Compatibility

Legacy Compatibility

From 1983 onwards, various companies worked on graphical user interfaces (GUIs) capable of running on PC hardware. With DOS being the dominant operating system several companies released alternate shells, e.g. Microsoft Word for DOS, XTree, and the Norton Commander. However, this required duplication of effort and did not provide much consistency in interface design (even between products from the same company).

Later, in 1985, Microsoft Windows was released as Microsoft's first attempt at providing a consistent user interface (for applications). The early versions of Windows ran on top of MS-DOS and its clones. At first Windows met with little success, but this was also true for most other companies' efforts as well, for example GEM. After version 3.0 (1990), Windows gained market acceptance.

Windows 9x used the DOS boot process to launch into protected mode. Basic features related to the file system, such as long file names, were only available to DOS when running as a subsystem of Windows. Windows NT runs independently of DOS but includes NTVDM, a component for simulating a DOS environment for legacy applications.