Evolution & Development History
In the late 1960s a combined project between researchers at MIT, Bell Labs and General Electric led to the design of a third generation of computer operating system known as MULTICS (MULTiplexed Information and Computing Service). It was envisaged as a computer utility, a machine that would support hundreds of simultaneous timesharing users. They envisaged one huge machine providing computing power for everyone in Boston. The idea that machines as powerful as their GE-645 would be sold as personal computers costing only a few thousand dollars only 20 years later would have seemed like science fiction to them. However MULTICS proved more difficult than imagined to implement and Bell Labs withdrew from the project in 1969 as did General Electric, dropping out of the computer business altogether.
One of the Bell Labs researchers (Ken Thompson) then decided to rewrite a stripped down version of MULTICS, initially as a hobby.
He used a PDP-7 minicomputer that no was using and wrote the code in assembly. It was initially a stripped down, single user version of MULTICS but Thompson actually got the system to work and one of his colleagues jokingly called it UNICS (UNiplexed Information and Computing Service). The name stuck but the spelling was later changed to UNIX. Soon Thompson was joined on the project by Dennis Richie and later by his entire department.
UNIX was moved from the now obsolete PDP-7 to the much more modern PDP-11/20 and then later to the PDP-11/45 and PDP-11/70. These two latter computers had large memories as well as memory protection hardware, making it possible to support multiple users at the same time. Thompson then decided to rewrite UNIX in a high-level language called B. Unfortunately this attempt was not successful and Richie designed a successor to B called...