Ken Thompson wrote the first UNIX system in assembly language on a PDP-7 in 1969. That that time Unix was called Unics as a joke on Multics. The first Unix was the operating system for Space Travel, a graphical game that displayed the motion planets.
Reference:
http://upload.wikimedia.org/wikipedi...ix-history.svg
Also, see attached paper:
Quote:
The Evolution of the Unix Time-sharing System*
Dennis M. Ritchie
Bell Laboratories, Murray Hill, NJ, 07974
ABSTRACT
This paper presents a brief history of the early development of the Unix operating system. It concentrates on the evolution of the file system, the process-control mechanism, and the idea of pipelined commands. Some attention is paid to social conditions during the development of the system.