Thanks goodness Dr. Thompson did what he did. My Mac thanks you, sir!
In August 1969, Ken Thompson, a programmer at AT&T Bell Laboratories, saw the monthlong absence 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. PDP-7 minicomputer, spending one week each on the operating system, a shell, an editor and an assembler.
[From Unix turns 40: The past, present and future of the OS | Mac OS X - Page 1 | Macworld]
