IMSAI 8080 (our show so far...)

From: Bill Sudbrink <bill_at_chipware.com>
Date: Tue Jun 29 13:01:45 1999

Ok. There is a 16 pin ribbon cable between
the front panel and the MPU-A card. It has
dip headers on both ends and is soldered on
the front panel and socketed on the MPU-A.
looking at the front panel side, the pins
on opposite sides are connected by original
traces on the printed circuit board. That
is (excuse the bad ASCII art):

O O O O O O O O
| | | | | | | |
O O O O O O O O

So I guess that is 1 to 16, 2 to 15, etc.

Looking at the MPU-A... WELL SHIT! Sorry,
I think I found it... no, that didn't help.
There was a single strand from a braided wire
resting across pins 7 and 8 on the rightmost
N8T97N, however removing it doesn't seem to
have helped. Anyway, the MPU-A only seems to
have connections to pins 1-8 of the dip socket
where the ribbon from the front panel connects.

If I plug in the cable reversed, front panel
behavior gets worse. That is, strange addresses
pop up all over, the EXAMINE switch causes all
sorts of odd activity. One odd thing is that the
STOP switch still works.

Anyway, there are no patches or cut traces on
the MPU-A that I see. There are lots of patches
on the front panel.

Thanks,
Bill
Received on Tue Jun 29 1999 - 13:01:45 BST