M7264 Troubleshooting

Glen Slick glen.slick at gmail.com
Tue May 21 19:34:16 CDT 2019

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.

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