MS-DOS is an acronym for Microsoft Disk Operating System, and DOS is an acronym for a Disk Operating System. In a general sense, DOS refers to just about any operating system. More commonly, it describes the operating system Microsoft developed in 1981 for IBM’s line of personal computers. Though syntactically (language) distinct, DOS shares similarities with a Unix shell. It has a command-line interface and analogs to many common Unix commands. However, DOS is a 16-bit, single-user operating system that does not support multi-tasking. It is far easier to administer than Unix, but less powerful. Compared to modern graphical interfaces, such as the Mac OS and Windows, it is also not particularly user-friendly.
DOS began as QDOS (Quick and Dirty Operating System), a variation of an older operating system called CP/M. It was initially produced by Seattle Computer Products; Microsoft then bought the rights to it and re-engineered it for IBM’s new line of PCs. At this point, two distinct but similar versions of DOS emerged:
- PC-DOS, which is what IBM distributed with its computers
- MS-DOS, which Microsoft licensed to clone vendors
In 1985, Microsoft released Windows 1.0, a graphical interface that ran on top of DOS. Providing a friendlier environment than the DOS command-line, Windows grew in popularity, especially after its 3.0 release in 1990. Other graphical interfaces, such as GEOS, were also developed for DOS, but none have had widespread popularity.
With the release of Windows 95/98, Windows NT and Windows 2000, DOS has faded in importance. Although Windows 95 and 98 includes a built-in version of DOS, it provides many of the functions DOS used to be responsible for. Windows NT is not based on DOS at all, though it does include a DOS-like command line interface. As 32-bit, and in the near future, 64-bit, applications become the norm, DOS will become increasingly inadequate. Nevertheless, there are still many programs, especially games, that require DOS to run. It also provides a convenient command-line for those situations where a graphical interface is less efficient.
There are a number of DOS alternatives and/or enhancements available. Two of the more prominent include FreeDOS and DR-DOS. FreeDOS is a version of DOS that is freely distributed under the GNU General Public License. Though not completely compatible with MS-DOS, it will run many DOS programs. For more information, visit the FreeDOS Web site.
Lineo produces an MS-DOS compatible product called DR-DOS. It sports advanced features, including multi-tasking capabilities. For more information, visit the DR-DOS home page.