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TOPS(1) A family of operating systems from Digital Equipment that ran on the PDP-6, DECsystem 10 and DECsystem 20 computers. TOPS was later renamed TOPS-10, and TOPS-20 was a completely new OS based on TENEX, developed by Dan Murphy at Digital and members of BBN. TOPS-20 added advanced features for the mid-1970s such as virtual memory.
(2) (Transparent OPerating System) An earlier peer-to-peer LAN from Sitka Corporation, Alameda, CA, that used the LocalTalk access method and connected Apple computers, PCs and Sun workstations. Its Flashcard plugged LocalTalk capability into PCs.