A correction to the comment on the source of CB-UNIX.
I was the supervisor of the group in Columbus for a number of years that was
responsible for the development of CB-UNIX.  The system was derived
from the UNIX operating system that was used in the SCCS (Switching
Control Center System), which incidentally was the first application
of UNIX outside of research. (UNIX was running on an 11/20, at the time,
without memory management and we deployed the first version of SCCS
in New Jersey Bell in New Brunswick, NJ.)

The SCCS version of UNIX had a number of unique features for the times:
semaphores and line disciplines (in 1974!) for example. Hal Pearson
was responsible for semaphores, and Bill Snider for line disciplines.

Messages and shared memory were first added to CB-UNIX in about 1975 or
1976. Shared memory was called MAUS (pronounced moss, standing for
Multiple Access User Space) and was derived from an earlier version
done by R. J. Purdue.  CB-UNIX became rather widely accepted within BTL
as a base for turnkey Operations Systems--many of which have been
described in the BSTJ. Note that CB-UNIX was not a derivative of UNIX/RT, but
of Version 6 and Version 7.  PWB UNIX was also a derivative of Version 7.
USG UNIX was originally a derivative of Version 6 and 7 with some CB-UNIX
facilities added.  Eventaully a decision was made to consoldate to two
versions of UNIX:  UNIX/TS and UNIX/RT. RT was a derivative of MERT, and
TS a derivative of PWB UNIX. RT was to be used by Operations Systems, but
was never too widely accepted. Eventually, UNIX/TS was augmented to have
many of the features present in CB-UNIX (this was done by Roger Faulkner
at Indian Hill, BTL. This, in turn, became the base for UNIX 4.0, which
was never released externally. While this augmentation was going on, UNIX/TS
was being changed into UNIX 3.0 which was release externally as SYSTEM III.

In more recent history, CB-UNIX has been eliminated entirely in favor of
UNIX 5.0. (one reason is because it never ran on anything other than the 11/70)

I once had a viewgraph with all this on it which I had great fun trying to
explain.

Now for trivia: How many know where in UNIX lore you would find the following
quote:  "Values of beta will result in dom!"

                        Dale DeJager
                        AT&T Information Systems
                        Lincroft, N.J.