What is dos meaning?

DOS (short for Disk Operating System) is a command-line-based operating system widely used on IBM-compatible personal computers in the 1980s and 1990s. DOS was developed by Microsoft and was based on QDOS (Quick and Dirty Operating System) which was purchased from Seattle Computer Products. DOS was the primary operating system for IBM-compatible PCs until Microsoft's Windows 95 was released in 1995. DOS is still used today for certain specialized applications, embedded systems, and in some older legacy systems. Some common commands used in DOS include dir, cd, copy, and format. The most popular versions of DOS were MS-DOS (Microsoft Disk Operating System), PC DOS (IBM Personal Computer Disk Operating System), and FreeDOS (a free and open-source version of DOS).