[TUHS] Unix with TCP/IP for small PDP-11s

Clem Cole clemc at ccc.com
Mon May 22 07:26:42 AEST 2017

Actually, the 11/60's main claim to fame was it supposed to be a
'commercial' PDP-11 and was built for the small business market.  The WCS
was a side effect.

It was to built to run RSTS and RSX and had a commercial instruction set
exten *etc.*. Somebody had written a 'dentist office' package for it and a
'car dealership package' IIRC.    And was physically packaged a tad
differently than the other 11's as it was trying to be marketing to places
that might want to show it off instead of hiding it in a computer room.

The main competition at the time was the Burrough 1700 and the IBM System
38 and DEC was trying to find a system to compete in the market.   Now, the
B1700 is a very cool system and could swap its microcode depending on the
language running (it is also bit addressable). As I understand it from
talking to the 11/60s product manager many years later at a party, one of
the ideas was that the PDP 11/60 WCS an attempt to be able offer features
that might be needed to compete with it.

The the real truth was that issue in the original 11's had stored the ucode
in PROM and if an ECO went out the CPU boards had be swapped, so the chips
could be swapped at the factory.    Plus a number of places, like MIT and
CMU had been banging on DEC to make the ucoding of the system an available
option (CMU just built it's own the 11/40e that triple drip made for them).

Anyway, as the price of SRAM had fallen dramatically from when the 11 was
introduced, and the 11/60 was storing the primary ucode it, not PROM like
the other 45 and 40 class systems; WCS became a possible feature to expose.
  But, as I said, the problem was that the WCS tools were not very portable
and the microengine was (as I remember) not well enough documented.  Which
is why I don't think many people tried.

Also the 11/60 also had a unique feature we called the HCU instruction -
Halt and Confuse Microcode.  Unlike the 11/34 which had an Intel 8008 that
ran front (programmers) console, the 11/60's microcode loop read the LED's
and keypad.  But ... if the ucode took a dive, the only recourse was turn
off the system - as it would stop responding to anything (just like PC
years later ;-)  We never found what sequence caused it; but when I was
debugging the original 11/60 port of V6, I would run into a lot ;-)

IIRC - we realized on these pages that Dave Horsfall in OZ and I in Oregon
must have been doing similar work around the same time.  FWIW, my changes
made it back to AT&T via Ted and I believe eventually went out in the
System III release.   That said, I suspect if we were to compare our
patches I bet they are pretty similar.


On Sun, May 21, 2017 at 4:57 PM, Ron Natalie <ron at ronnatalie.com> wrote:

> The 11/60’s main claim to fame if I recall was a writable control store.
> Don’t know anybody who actually used that feature.
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