pdp11/84 PMI memory: What is the problem with Q bus?
cz at alembic.crystel.com
Wed Apr 22 19:09:37 CDT 2020
> So whatever the fault is (perhaps the QBUS block transfer issue reported
> up-thread), it must _seem_ to work, but fail in actuality. It would be
> interesting to appply a logic analyzer, and see what the bus transaction
> looks like, if it looks OK on the bus (in which case it's an internal
One possibility is that it's not handling multiple DMA devices talking
at the same time or calling to arbitrate the bus. Right now I have an
RL02 controller and the MTI controller but the RL02's are powered down.
I'll see if I can run it for a bit on RSX11M and get it to fault (and
backup my disk first as it's nice to have it working again).
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