DOS
DOS, short for "Disk Operating System", is an acronym for several closely related operating systems that dominated the IBM PC compatible market between 1981 and 1995, or until about 2000 if one includes the partially DOS-based Microsoft Windows versions 95, 98, and Millennium Edition.Related systems include MS-DOS, PC-DOS, DR-DOS, FreeDOS, PTS-DOS, ROM-DOS, Novell DOS, OpenDOS and