General Question about UNIBUS backplanes
jnc at mercury.lcs.mit.edu
Tue May 24 06:49:11 CDT 2016
> 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).
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