DOS (Disk Operating System) 1. A generic term describing an operating system (OS) that loads from a disk device when the computer system is turned on. Earlier, more primitive OSs loaded from magnetic tape or even paper tape, or were resident in memory. See also OS. 2. Referring to MS-DOS (MicroSoft Disk Operating System), a single-user, single-tasking OS released in 1981 for use in IBM personal computers (PCs) and compatibles. See also OS and PC. |