DEC PDP-11/45 backplane +5 ECO

Noel Chiappa jnc at mercury.lcs.mit.edu
Wed Apr 28 11:14:31 CDT 2021


    > From: Eric Smith

    > The KB11-B (original 11/70) and KB11-C (later 11/70) have essentially
    > the same changes as from the KB11-A to KB11-D

Speaking of which, two of the boards that are different in the KB11-D, from
the -A, are _identical_ to boards in the KB11-C - the M8123 ROM & ROM control
and the M8132 instruction register decode! (The M8123 is also different from
the M8133 board in the KB11-B.) Pretty wierd that the -11/45 and -11/70 CPUs
share two boards, but true! (The FP11 boards are the same in both, too.)


    > It sure would be nice to get backplane wirelists for all four (KB11-A,
    > -B, -C, and -D).

ISTR a previous, un-fulfilled request for the -11/70 wirelist, so it's been
missing for a while.

We _might_ have the -11/45 wirelist:

  http://www.bitsavers.org/pdf/dec/pdp11/1145/1145_System_Engineering_Drawings_Jun74.pdf

but it's short (pp. 128-132), so maybe it's not complete)? Two other
print sets seem to have the same list:

  http://www.bitsavers.org/pdf/dec/pdp11/1145/1145_System_Engineering_Drawings_Jun76.pdf
  http://www.bitsavers.org/pdf/dec/pdp11/1155/MP00039_1155vol1_Mar76.pdf

(pp. 45-49 and pp 131-135 respectively).


    > Also, I'm looking for a Field Maintenance Print Set for the RH70.

Heh. I didn't see it online; the manual:

  http://www.bitsavers.org/pdf/dec/unibus/CSS-MO-F-5.2-27_RH70_Option_Description_Feb77.pdf

is a CSS document, which makes no sense, because the CPU backplane is laid
out to have room for four, so it's an integral part of the /70 CPU - so why
is it a CSS product? Anyway, the print set listed there seems like it might
be a CSS thing, too.

I see that the CHM seems to have a set:

  https://www.computerhistory.org/collections/catalog/102749003

so maybe Al will take pity on us and scan it!

I looked in my /70 print set, and although it contains all sorts of odds and
ends (including MJ11 prints - which kind of half makes sense, since that was
the only main memory option on early /70's), it doesn't have the RH70. (I
didn't see the MJ11 prints on BitSavers, so I was thinking I was going to
have to scan them, but on further looking I found them on deramp.com.)

	Noel


More information about the cctech mailing list