Interesting... PDP-8/m Mem problems

From: Zane H. Healy <>
Date: Fri Nov 26 01:32:15 1999

OK, granted I don't know what I'm doing, but... I don't think there is
anything wrong with the G104 board. I've been examining E24 and E28. The
problem with E28 is it's not getting any input, and unless I'm mistaken E24
isn't either. The board is broken into 3 sections, and I've also checked
the section next to it to get a better idea of what I should be seeing.

Now for some very un-technical talk. I've been trying to find the lines
that bring the bits from the Core board to the G104 board. As far as I can
tell the bits are brought over on the back side of connectors 'F' and 'G'.
There are 12 dual pin groups. The four that correspond to E24 and E28
aren't acting right. With the logic probe, when examining locataions, I
only get a beep on the 8 that are acting right when it checks Memory
locations: xxx0 - xxx3 (the ones effected by the bad 8251 on the G227
board). On the other 4 I always get a beep, no matter what location.

So.... My conclusion is that the section on G104 that contains E24 and E28
isn't getting any bits, and may very well be a totally functional section.

Having said that, I'm more than a little stumped as to how to attack the
Core Board itself seeing as how it's sandwiched between two other baords.

| Zane H. Healy | UNIX Systems Adminstrator |
| (primary) | Linux Enthusiast |
| (alternate) | Classic Computer Collector |
| Empire of the Petal Throne and Traveller Role Playing, |
| and Zane's Computer Museum. |
| |
Received on Fri Nov 26 1999 - 01:32:15 GMT

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:32:30 BST