Source : Free On-Line Dictionary of Computing

Control Program for Microcomputers
     
         (CP/M) An early {microcomputer} {operating
        system} written by Gary Kildall of {Digital Research} for
        {8080} and {Zilog Z80}-based 8-bit computers.  CP/M was very
        popular in the late 1970s but was virtually wiped out by
        {MS-DOS} after the release of the {IBM PC} in 1981.
     
        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}.
     
        CP/M might have been the {OS} for the {IBM PC} instead of
        {MS-DOS} but Kildall wanted to keep control of his creation
        and only license it to IBM.  Big Blue however wanted to own
        and control it completely.  Kildall spent the day IBM's reps
        wanted to meet him enjoying the perfect flying weather in his
        private plane.
     
        [Did CP/M use the same {FAT} file system as MS-DOS?]
     
        (1996-01-07)