Source : Free On-Line Dictionary of Computing

PETSCII
     
         /pet'skee/ {PET} {ASCII}.  The variation (many
        would say perversion) of the ASCII {character set} used by the
        {Commodore Business Machines}' {PET} series of {personal
        computer}s and the later {Commodore 64}, {Commodore 16}, and
        {Commodore 128} computers.  The PETSCII set used left-arrow
        and up-arrow (as in old-style ASCII) instead of underscore and
        caret, placed the unshifted alphabet at positions 65--90, put
        the shifted alphabet at positions 193--218, and added {graphic
        characters}.
     
        [{Jargon File}]
     
        (1995-10-29)