The term PC-compatible, or PC for short, refers to the IBM PC and any of the many, many personal computers derived from it. From another angle, a PC is any computer that can run Microsoft's MS-DOS operating system and whose expansion bus is compatible with the ISA bus in the original IBM PC. The category includes the PC, XT, AT, PS/2, and most compters with 80x86, Pentium, and compatible CPUs. It does not include the Macintosh, Amiga, or IBM mainframes, though these and other computer types may have ports that are similar to the parallel port on the PC"
Jan Axelson, Parallel Port Complete