Source : Free On-Line Dictionary of Computing

P-code
     
        The intermediate code produced by the {Pascal-P} compiler.
        Assembly language for a hypothetical stack machine, the
        P-machine, said to have been an imitation of the instruction
        set for the Burroughs Large System.  The term was first used
        in Algorithms + Data Structures = Programs, N. Wirth, P-H
        1976.  Byte articles on writing a Pascal Compiler in Northstar
        BASIC (ca Aug 1978) also used the term.  Later used in Apple
        Pascal, and as the intermediate language in the UCSD P-system.
     
        Variants: P2 P-code, P4 P-code, UCSD P-code, LASL P-code.
     
        Address: USUS, Box 1148, La Jolla, CA 92038, USA.
     
        ["A Comparison of PASCAL Intermediate Languages", P.A. Nelson,
        SIGPLAN Notices 14(8):208-213 (Aug 1979)].
     
        (1995-10-15)