PDP-11/44 problem - RUN stays on
henk.gooijen at oce.com
Sat Nov 11 12:04:08 CST 2006
I pulled all boards from the 11/44 backplane and used an eraser
to clean all the contact fingers. Then I vacuumed the slots.
After wiping the boards clean of any small particles, I reseated
the boards ... the system still shows the same problem, the RUN
LED stays on and I don't get the >>> prompt.
Then I swapped the CTRL (M7095) board. ^P gives me the >>> again.
However, "H" (halt) gives the response "?Failed to halt".
The "T" (selftest) command seems OK, the LED on the MFM board is
briefly ON. As the MFM board was also suggested to be causing
problems, I replaced the MFM board.
Now the RUN LED stays OFF! However, I get an other problem.
The VT100 displays:
?22 CP HUNG
I can enter the T and the H command. That works fine.
But, for example, an E (examine) command gives the ?22CP HUNG.
When I install the original MFM board again, the RUN LED stays
ON, but the "E 2" command gives the response
" P 00000002 000001"
and the H command says "?Failed to halt".
According to the documentation you can do EXAMine commands
while the system is running, but you can not do a DEPosit.
Proof: I entered "D 2 2" and the response is "?Halt CP".
So, one MFM board gives "?22 CP HUNG", but the RUN LED is OFF,
the other MFM board allows examine, but the RUN LED stays ON,
and you can not halt the processor.
I am still reading, but give these symptoms perhaps clues?
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