[TUHS] Non-PDP 16-Bit UNIX Inside AT&T?

[segaloco via TUHS]

I briefly broached this topic in a separate thread recently, but just
received another document that even further muddies the waters.  So last
week I received a few Dimension 400 PBX manuals detailing the system
hardware.  Among the components was the MC3 processor, a 16-bit
mini-computer core running whatever AT&T Generic was distributed for
these PBX systems.

Well, just today I received a few very late copies of the Western
Electric Engineer, one of the various magazines distributed inside of
the Bell System.  Both the Bell Labs Record and WECo Engineer include
small "new developments/products"-type sections in the middle, usually
on cardstock rather than the usual printed papers.  In 1983's second
issue of the magazine, there is a description of the Dimension 85
system.  Obviously it is also a part of the Dimension family, but
distinct from the Dimension 400 PBX from what I can tell.

The writeup goes on to describe the "applications processor" of the
system as such:

> The main central processing unit is
> a 16-bit microprocessor that drives the
> AP/UNIX operating system.

First off, this is first I've ever heard of "AP/UNIX".  Google's stupid
little crapbot spit out a summary of some merging of UNIX and the Pick
operating system, but I don't think that is what is being described
here.  Rather, my assumption is the "AP" stands for application
processor.  In any case, there is no further description of *what*
16-bit microprocessor is being referred to here, but to burst my own
bubble, a late 70s WECo microprocessor symposium document contains
several articles on BTL experiments with the Intel 8086 and the BTL
internal manuals for Releases 5.0 and 6.0 contain, among other things,
the BASIC-16 SGS, which was BTL's SGS for the 8086.

So inconclusive whether the microprocessor being described is some long
lost BellMAC-16, something related to the MC3, another BTL design, or
simply a commodity 16-bit CPU.  Either way, the AP/UNIX mention is
interesting.

Has anyone heard of the WECo MC3 mini-computer, AP/UNIX as produced by
BTL, or any 16-bit microprocessors (BellMAC or otherwise) inside AT&T
running UNIX aside from the PDP-11 and allegedly Intel 8086?

- Matt G.

P.S. I'll be scanning these soon.  I love the level of heady detail
some of these articles get into.  There is a whole article with 4
authors between two Works plants titled "A Mathematical Model for
Predicting the Behavior of Retractile Telephone Cords" which goes on to
list a number of equations, tools, and procedures for determining and
verifying various characteristics of modular telephone springcords.
That's the kind of oddly specific analysis that really tickles my brain.