From: Greg Green (ggreen_at_cs.washington.edu)
Date: Tue Jan 06 2004 - 19:43:31 PST
This paper describes the design and implementation of UNIX in 1974. At
the time it was operating in about 40 installations of PDP-11
systems. The file system was described in some length. The main
differences between the system as described and modern systems was the
small file size and only having user and other permissions. The main
elements were essentially the same as they are now. Process management
and pipes for IPC were described. The main concepts of a shell were
described, running other processes, redirecting output, filters, and
backgrounding processes. The beginnings of the signal subsystem are
described, but obviously still in a nascent state.
I have read a couple of books on UNIX design and implementation, so I
found nothing particular interesting in this paper, other than being a
concise explanation of some of the design decisions. It was
interesting that there was some data on reliability of the system, ie
longest up time of 2 weeks and a 98% average up-time. About on par
with modern Windows NT systems, but much worse than what we see with
Linux systems. I suppose that is due to the fact that the system was
so small (42K bytes) and the implementers were competent people.
A point was made that the system was successful because it just grew,
instead of being designed for a particular purpose. He also states
that since they are programmers, the system was designed to support
programmer users, as opposed to the general population. That hasn't
changed much in the intervening years.
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