Disk Operating System (DOS)

Short for disk operating system, DOS refers to the original operating system developed by Microsoft for IBM, sometimes also referred to as MS-DOS (Microsoft disk operating system). Once the standard operating system for IBM-compatible PCs, DOS started to decline with the rise of Microsoft Windows.

The initial versions of DOS were very simplistic and resembled another operating system called CP/M. At the height of its popularity between 1980 and 1995, DOS was fundamentally a 16-bit, single-user, single-task operating system, so its inability to support modern computer applications led to a shift away from DOS as the foundation for Windows 95 and 98. Subsequent Microsoft operating systems (including those as recent as the 32-bit Windows 10) support DOS commands and programs, but DOS is no longer required to run Windows.

Small, niche communities of users still favor the nostalgic, distraction-free interfaces of DOS derivatives like FreeDOS and DR-DOS to run legacy software, classic DOS games, and embedded systems. Game of Thrones author George RR Martin has been a vocal DOS advocate, citing his preference for word processors run on DOS because they do not use spell check to correct the vocabulary of his fantasy novels.

For Denial of Service (DoS), see DoS attack.

Examples of DOS commands

The DOS command-line on modern Windows systems can be accessed from the Start menu by typing cmd and pressing the Enter key.