TOPS-20

The TOPS-20 operating system by Digital Equipment Corporation (DEC) was a proprietary OS used on some of DEC's 36-bit mainframe computers. The Hardware Reference Manual was described as for "DECsystem-10/DECSYSTEM-20 Processor" (meaning the DEC PDP-10 and the DECSYSTEM-20). TOPS-20 competed with TOPS-10, ITS and WAITS—all available for the PDP-10(all of which were notable time-sharing systems) during this timeframe.

TOPS-20

The TOPS-20 operating system by Digital Equipment Corporation (DEC) was a proprietary OS used on some of DEC's 36-bit mainframe computers. The Hardware Reference Manual was described as for "DECsystem-10/DECSYSTEM-20 Processor" (meaning the DEC PDP-10 and the DECSYSTEM-20). TOPS-20 competed with TOPS-10, ITS and WAITS—all available for the PDP-10(all of which were notable time-sharing systems) during this timeframe.