On Fri, Jan 1, 2021 at 10:06 PM Eric Smith <spacewar at gmail.com> wrote:
On Fri, Jan 1, 2021 at 10:04 PM Josh Dersch via cctalk
cctalk at classiccmp.org> wrote:
Discovered a broken wirewrap wire on the 11/70
I'm slowly working on, it's
on the last slot (44), and runs from BD2 to ??. White wire, part of a
white/black twisted pair. I've been looking but haven't found a wire list
for the backplane
There would be two different 11/70 backplane wirelists, depending on
whether your CPU is a KB11-B or a KB11-C. Unfortunately I don't have either
If your 11/70 has an M8133 and an M8138, it's a
If it has an MB8123 and MB8138-YA, it's a KB11-C.
I have a KB11-C here.
You're undoubtedly aware that the A/B section of
slot 44 is for the Unibus
cable or terminator, so BD2 is signal BR4 L. It should probably go to the
BR4 L pin of the slot 44 SPC, which would be pin DH2, which would be bussed
through DH2 of the other SPC slots (40-43).
You know, that really should have occurred to me. Convenient that the
break happened on such a convenient pin!
Thanks for the tip, I'll double-check everything tomorrow and see if I can
find my wire-wrap tool...
RH70 Massbus controllers normally use BR5 L, but I suspect that the BR4 L
line would be wired to their slots as well. I don't have an RH70 print set,
so I don't know the details. From the RH70s (or slot 40, if BR4 L doesn't
go to the RH70s), I would expect it to go to the Trap & Msc Control board
(TMCB) in slot 11, pin FP1.