/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]