(University of California at San Diego p-System) An early software development system designed for cross-platform portability. Source programs (BASIC, Pascal, etc.) were compiled into intermediate "p-code" programs, which were executed by an interpreter in the target machine. The UCSD p-System was available for the IBM PC in 1981, but was not very popular. Like Java Java, which is widely used today, uses a similar intermediate code concept to run the same source program on different platforms (see Java).