"With your birth as our starting point, then, let's look at the
biggest desktop OS milestones of the past 40 years.
Unix was brought to life on a spare DEC PDP-7 at AT&T Bell
Labs.When AT&T decided to abandon the Multics (Multiplexed
Information and Computing Service) operating system on its
minicomputers, Ken Thompson and Dennis Ritchie cobbled together an
operating system so they could continue to play a space travel game
that Thompson had developed. A colleague gave the system a jokey
name based on Multics -- UNICS, the Uniplexed Information and
Computing Service, which morphed into UNIX or Unix. 1976
"Intergalactic Digital Research's maverick brain Gary Kildall
creates CP/M, a simple microcomputer operating system for simple
microcomputers. It would be the model for command-line DOS
variations for two decades."