Differences between PDP-11/83-84 M8190-AB/AC and AD/AE CPU cards

Jerome H. Fine jhfinedp3k at compsys.to
Sat Feb 7 17:03:05 CST 2015

 >Noel Chiappa wrote:

>    > From: Jerome H. Fine
>    > The MSV11-JB (1 MB) and MSV11-JC (2 MB) are used in the PDP-11/84. The
>    > MSV11-JD (1 MB) and the MSV11-JE (2 MB) are used in the PDP-11/83.
>Err, not sure this is correct: I got an 11/84 with an MSV11-JD in it. As
>someone pointed out in a later message, the difference between the B/C and
>D/E is that the B/C only work as PMI memories, their QBUS functionality has
>some issues (IIRC, something to do with QBUS block transfers not working
>    > In addition, for at least the PDP-11/83, the PMI memory must be placed
>    > into the backplane ahead of the CPU for the memory to function as PMI
>    > memory. That may be the only position allowed for the memory for the
>    > PDP-11/84.
>The 11/84 backplane has two special Q22/CD slots after the processor slot
>which the memory goes in, with the CD sections wired to through-connect the
>PMI pins.
THANK  YOU for both corrections.

With regard to the MSV11-JD in the PDP-11/84, was this board placed 
after the
KDJ11-AE board or before it?  I suspect that it would be after the CPU when
these boards are used in a PDP-11/84 backplane, but I wanted to confirm this
for other potential PDP-11/84 users.

Also, has anyone ever used a KDJ11-AC board with the 15 MHz crystal in the
PDP-11/84 backplane?  I can't see why it should not work, but just maybe
the PDP-11/84 backplane and a simple KDJ11-AC board are not compatible.
It seems unlikely, but it also seems best to ask.

Jerome Fine

More information about the cctech mailing list