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For other meanings of DOS or DoS, see DOS (disambiguation).
DOS most often stands for disk operating
system, a type of operating system for computers that provides the abstraction of a file system
resident on the disk.
In particular, DOS refers to the family of related operating systems which dominated the IBM PC compatible market for the decade between 1985 and
1995: PC-DOS, MS-DOS, DR-DOS, FreeDOS, and
several others.
MS-DOS (and the IBM PC-DOS which was licensed therefrom), and its predecessor, QDOS, was
a successor to CP/M (Control
Program / (for) Microcomputers)—which was the dominant operating system for 8-bit
Intel 8080 and Zilog Z80 based microcomputers.
Early versions of Microsoft Windows were programs which ran
under DOS. Later versions were launched under DOS but "extended" it by going into protected mode. Still later versions of MS
Windows ran independently of DOS but included much of the old code such that it could run in virtual machines under the new OS and the latest versions of MS Windows are continually dropping ever
more of the DOS ancestry.
Under Linux it's possible to run copies of DOS and many of its clones under
dosemu (a Linux native virtual
machine program for running real mode programs). There are a number of other
emulators for running DOS under various versions of UNIX, even on non-x86 platforms.
Prior to (and to some extent concurrently) the development of the IBM PC compatible family of microcomputers, several other
operating systems for other architectures were already known as DOS, notably:
- The DOS initial/simple operating system for the IBM System/360 family of mainframe computers (it later became DOS/VSE, and was eventually just
called VSE).
- The DOS operating system for DEC
PDP-11 minicomputers (this OS and
the computers it ran on were nearly obsolete by the time PCs became common, with various descendents and other
replacements).
- The DOS operating system for the Apple Computer's Apple II family of computers. This was the primary operating system for this family from
1979 with the introduction of the Disk ][ floppy disk drive until 1983 with the introduction of ProDOS.
See also: List of DOS commands
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