Richard Owlett writes:
Unix was a response to the needs of a large data center with possibly
thousands of users.
No it wasn't. Unix was a response to Multics, which *was* aimed at
systems with thousands of users. If you want to see a truly complex
system of permissions and access controls look at Multics. It was aimed
at universities and similar institutions that wanted to serve large
numbers of users on interactive terminals. It competed with the likes
of MTS and Plato and was going to solve all security problems (such as
they were at the time).
Data centers were something else again and used IBM hardware and
software. They were mostly batch: IBM's multiuser software was
atrocious but it's job control, scheduling, and accounting stuff was to
marvel at.
Unix was aimed at small multiuser interactive systems running on
minicomputers. The VAX 11/780 soon became the standard Unix box.