MCT Serial board mystery - Can you crack the pinout code?

[drlegendre .]

Jules & All,

On Sat, Nov 15, 2014 at 3:18 PM, Jules Richardson <
jules.richardson99 at gmail.com> wrote:

>
> Are you even sure that it's intended as a terminal board, rather than for
> some other peripheral that happens to be serial in nature?
>

Now why did you have to go and ask +that+? ;-)

No, I guess I don't know for sure, but here's what I do know - the last
owner did have +some+ way of talking to the system (in its previous
configuration), and this is the +only+ board in the lot that even comes
close to resembling a communications card.  The other boards are a Z-80
CPU, a 64K dynamic RAM and a dual floppy-disk controller.

The Z-80 CPU board does have both serial & parallel I/O edge-connectors on
it, but they look to have had little to zero use.. maybe one or two
connection cycles at most, perhaps just one cycle for factory QA testing.

Also, and this was dumb of me, I recall the serial board having a cable
+soldered+ directly to it. It only had 3 wires which terminated in a 25-pin
sub-D male connector, with only 3 pins installed. It struck me (like much
of the system) to have been a careless bodge or hack of some sort, so I
must have de-soldered it. Now, I can't even locate that cable, or tell
where it was previously attached.