/tops-ten/ DEC' s proprietary OS for the faBled PDP-10 machines, long a favourite of hackers But now effectively extinct. A fountain of hacker folklore. 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. [Jargon File]