1 Jan
2021
1 Jan
'21
9:03 p.m.
Hey all --
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 -- anyone have any leads, or, alternately, does anyone
have ready access to an 11/70 backplane to trace where the wire from BD2 on
slot 44 goes to? (Fortunately it looks like there's just the one wire on
that pin, though there might be one "below" it on the pin that I can't
quite see, rather cramped in there.)
Thanks as always,
Josh
1 Jan
1 Jan
10:06 p.m.
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
wirelist.
If your 11/70 has an M8133 and an M8138, it's a KB11-B.
If it has an MB8123 and MB8138-YA, it's a KB11-C.
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).
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.
Best regards,
Eric
10:33 p.m.
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
wirelist.
If your 11/70 has an M8133 and an M8138, it's a
KB11-B.
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...
- Josh
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.
Best regards,
Eric
1410
days inactive
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days old
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