DOS

This term is an acronym for Disk Operating System. While it refers to a general category of operating systems, it is most frequently used to refer specifically to MS-DOS or PC-DOS, the command-line systems prevalent in the 1980s and early 1990s.

In modern technical discourse, the term is often used to evoke a sense of legacy computing or "retro" technology. It describes an environment where users interact with the computer via text commands rather than a graphical user interface (GUI).