What Is DOS?

DOS, an acronym for 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 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 graphical interfaces such as Windows and Mac OS X, it's also not particularly user-friendly.

With the development of Windows, MS-DOS has faded in importance. However, you can still run some DOS commands at the command prompt in current versions of Windows, which can be useful in situations where a graphical interface is less efficient.

For some time, it has been widely acknowledged that DOS is insufficient for modern computer applications. Microsoft Windows helped alleviate some problems, but still, it sat on top of DOS and relied on DOS for many services. Even Windows 95 sat on top of DOS. Newer operating systems, such as Windows NT and OS/2 Warp, do not rely on DOS to the same extent, although they can execute DOS-based programs. It is expected that as these operating systems gain market share, DOS will eventually disappear. In the meantime, Caldera, Inc. markets a version of DOS called DR-OpenDOS that extends MS-DOS in significant ways.