"In August 1969, Ken Thompson, a programmer at AT&T
subsidiary Bell Laboratories, saw the month-long departure of his
wife and young son as an opportunity to put his ideas for a new
operating system into practice. He wrote the first version of Unix
in assembly language for a wimpy Digital Equipment Corp. (DEC)
PDP-7 minicomputer, spending one week each on the operating system,
a shell, an editor and an assembler.
"Thompson and a colleague, Dennis Ritchie, had been feeling
adrift since Bell Labs had withdrawn earlier in the year from a
troubled project to develop a time-sharing system called Multics
(Multiplexed Information and Computing Service). They had no desire
to stick with any of the batch operating systems that predominated
at the time, nor did they want to reinvent Multics, which they saw
as grotesque and unwieldy."