A 1974 paper in Communications of the ACM
[Ritchie-Thompson] gave Unix its first public
exposure. In that paper, its authors described the unprecedentedly
simple design of Unix, and reported over 600 Unix installations. All
were on machines underpowered even by the standards of that day, but
(as Ritchie and Thompson wrote) “constraint has encouraged not
only economy, but also a certain elegance of design”.
The first Unix of which it can be said that essentially all of
it would be recognizable to a modern Unix programmer was the Version 7
release in 1979.
The first Unix user group had formed the previous year. By this time
Unix was in use for operations support all through the Bell System
[Hauben], and had spread to universities as far away
as Australia, where John Lions's 1976 notes [Lions] on
the Version 6 source code became the first serious documentation of
the Unix kernel internals. Many senior Unix hackers still treasure a
The Lions book was a samizdat publishing sensation. Because
of copyright infringement or some such it couldn't be published in the
U.S., so copies of copies seeped everywhere. I still have my copy,
which was at least 6th generation. Back then you couldn't be a kernel
hacker without a Lions.