One notable early disk operating system was CP/M, which was supported on many early microcomputers and was closely imitated by Microsoft's MS-DOS, which became widely popular as the operating system chosen for the IBM PC (IBM's version of it was called IBM DOS or PC DOS).
* UNIVAC EXEC 8 – UNIVAC 1108, 1967, v OS 2200 Unisys Clearpath Dorado, danes.