Mystery LSI-11 board

[tom ponsford]

Paul Koning wrote:

 >> You have bad html (local filename reference for the photos); pasting
 >> the name part into the rest of the URL gets the pictures.

Oops

Sorry a fixed url:
http://personal.riverusers.com/~dponsford/qbus/index.html


 >> That's definitely not a DEC board. For one thing, a Qbus board
 >> wouldn't have gray handles, it would have maroon handles (that's what
 >> the M in board part numbers refers to).

Well this is a qbus board as it came out of a qbus chassis and the grey 
handles do have DEC
on them! But I agree I think this may be a third party/prototype board! 
However there is an
assembly number and other production artifacts that lead me to believe 
this is not a
prototype board in the strict sense.

My first instinct with the mystery board was that it was a modified 
production board rather than a prototype

There is a 24 pin gold-colored chip in the center of the board, labeled :
IM5200CJG
 i 7608
 and in the lower corner FPLA-1

The CPU board does have the 5th socket filled with the FIS/CIS ( 
23-003B5) option,

I believe some of the operation of the board has to be a sort of 
termination like a TEV11, which
is required for the LSI-11 to operate, and the location, the last board 
on the qbus, is the obvious
location for the termination board. Having no photo of the TEV11 or 
REV11, I though this may be one!

 >> Second, the rats nest of wires on the back goes way beyond anything
 >> that DEC would ship (far too many wires) and the "slap them anywhere"
 >> routing is much sloppier than the rework I have seen coming out of
 >> DEC. It's just barely possible you might see this in a prototype,
 >> though almost always prototypes would be done a lot more cleanly than
 >> that. But for sure you would not see that in a production board.


It could be a prototype board, but I do have a few circa 1974 DEC unibus 
boards
that do have as much as (or more) wirewrapping!

As this computer was from the U of A, it might have been used in some 
intructional/development program.

The chassis is not a DEC product, more of an OEM/ development project. 
The front of the computer says:

LSI-11 MICROCOMPUTER
Microprocessor Development System
University of Arizona

with a few micro-toggle swirches (LTC on/off, Enable/Halt and 
Initialize) as well as small lights (Running, halt, D.C. On,
Enable )
.

Cheers

Tom

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