TENEX (operating system)

TENEX was an operating system BBN Technologies built in 1969 for the PDP-10 mainframe, and it later formed the basis of Digital Equipment Corporation's TOPS-20. It introduced a full virtual memory system that gave every program its own 18-bit, 262,144-word address space, managed by a pager that BBN built specialized hardware to support. Its command line environment favored long, descriptive commands, such as spelling out a directory listing rather than Unix's terse ls, and it offered automatic command completion by pressing escape as well as a help system triggered by typing a question mark. TENEX was popular on the PDP-10 market, and its successor TOPS-20, nicknamed TWENEX, stayed influential into the early 1980s before users largely moved to Unix and VAX/VMS. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/