TOPS-10

/tops-ten/ n. DEC's proprietary OS for the fabled PDP-10 machines, long a favorite of hackers but now effectively extinct. A fountain of hacker folklore; see appendix A. See also {ITS}, {TOPS-20}, {TWENEX}, VMS, operating system. TOPS-10 was sometimes called BOTS-10 (from `bottoms-ten') as a comment on the inappropriateness of describing it as the top of anything.