> From: Bill Degnan > I removed the core backplanes and returned the DD11-C to the orig > config next to the CPU. I re-inserted cards as-was. I am not getting > comms from the M7856.
Ugh. Not good. Does it respond on the UNIBUS? (I.e. if you try to read the registers from the front panel?) > I may have shorted the card. If you somehow plugged it into one of the core backplanes, good chance, alas. They have either -15V or +20V (I think the latter, for the MM11-U) running around on various pins. (Oh, BTW, you probably already know this, but just in case not: those backplanes take specific boards in specific slots; check the manuals/prints for the correct slots.) Do you have a spare M7856 you can swap in to make sure the machine is otherwise functional? If not, let me know, I have a bunch of spare M7800's, I can send you one (known, tested good). Noel