Re: PDP-11/70 backplane wire list
On Fri, Jan 1, 2021 at 10:06 PM Eric Smith wrote: > On Fri, Jan 1, 2021 at 10:04 PM Josh Dersch via cctalk < > cctalk@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 > >
Re: PDP-11/70 backplane wire list
On Fri, Jan 1, 2021 at 10:04 PM Josh Dersch via cctalk < cctalk@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
PDP-11/70 backplane wire list
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
