M7264 Troubleshooting

Glen Slick glen.slick at gmail.com
Tue May 21 20:01:28 CDT 2019

On Tue, May 21, 2019 at 5:34 PM Glen Slick <glen.slick at gmail.com> wrote:
> On Tue, May 21, 2019 at 4:56 PM Noel Chiappa via cctalk
> <cctalk at classiccmp.org> wrote:
> >
> > Well, I verified that the LSI-11/2 should work in a Q22 backplane -
> > in the sense that the only pins it tries to talk to are standard
> > QBUS pins, and AF1/AH1 for SRUN. It doesn't drive BREF, which might
> > cause issues in later QBUS systems.
> >
> > (It doesn't seem to work with Q18 memory, such as the MSV11-D. Attempts to
> > write 0 to memory from ODT wind up leaving the bits in the high byte set.
> > I have no idea why - anyone have any ideas? With Q22 memory, the symptoms
> > are even stranger; the system hangs with the 'run' light on - even with
> > the HALT switch on! Luckily I had an MMV11, and it worked OK with that.)
> Q22 memory uses BC1, BD1, BE1, BF1 for BDAL 18L, BDAL 19L, BDAL 20L, BDAL 21L
> According to the M7270 LSI-11/2 Microcomputer Module User's Guid, it
> uses BC1, BD1, BE1, BF1 for SCLK3 H, SWMIB18 H, SWMIB19 H, SWMIB20 H.
> I haven't found a scan of the KD11-H Field Maintenance Print Set MP-00050.

I just found an online scan of MP00495 KD11-HA LSI11 CPU Field
Maintenance Print Set.

It does show SCLK3 H, SWMIB18 H, SWMIB19 H, SWMIB20 H being driven on
BC1, BD1, BE1, BF1 for the M7270 LSI-11/2. So that seems like it might
be an issue with Q22 memory.

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