Information Research Services Updated: 19 August 1997
        TOPS-20 (the direct descendant of TOPS-10) was implemented with upgraded facilities based on multi-process operating system advances including concurrent interactive timesharing and multi-stream batch. TOPS-20 was also available with a variety of unbundled higher level language compilers and application tools such as FORTRAN, COBOL, BASIC, ALGOL, CPL, APL and Data Base Management.