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.