CP/M

CP/M: /C-P-M/ n.  [Control Program/Monitor; later
   {retcon}ned to Control Program for Microcomputers] An early
   microcomputer {OS} written by hacker Gary Kildall for 8080- and
   Z80-based machines, very popular in the late 1970s but virtually
   wiped out by MS-DOS after the release of the IBM PC in 1981.
   Legend has it that Kildall's company blew its chance to write the
   OS for the IBM PC because Kildall decided to spend a day IBM's reps
   wanted to meet with him enjoying the perfect flying weather in his
   private plane.  Many of CP/M's features and conventions strongly
   resemble those of early {DEC} operating systems such as
   {{TOPS-10}}, OS/8, RSTS, and RSX-11.  See {{MS-DOS}},
   {operating system}.