PDP-11/44 problem - RUN stays on
henk.gooijen at oce.com
Wed Nov 8 15:49:51 CST 2006
>>> However, ... besides the DC ON light, the RUN light
>>> stays ON too. I am sure the RUN light should go OFF.
>Wasn't there a discussion a long while ago about these same symptoms?
Yes, but that was about the 11/34, but it applies here too!
But I remember something about voltage comparators on the CIM, M7090.
>iirc. The run light may stick on if the grant request line gets broken.
>This can be caused by missing/loose/bad cards, missing grant jumpers, etc.
>(this from memory, so I may be remembering it wrong)
No, that's correct.
Just to make sure, I just did 2 simple checks.
1) I removed the M9202 that connects the CPU backplane to the next one,
and inserted a M9302 as terminator in the CPU, last slot position A-B.
2) I removed the M9302 (basically leaving things open. In a light-loaded
system you can try that. Well, the 11/44 CPU backplane has not much
space for peripherals ... the quad SPC slot has a G7273, so that's OK,
and the hex slot has a Quadrasync E (wasn't that on the list last week?)
I didn't know I had such a board! (and thus probably the doc too!
I haven't looked at the 11/44 for over a year).
Both checks are negative, that is, RUN stays ON, and moving the switch to
CONT/HALT/BOOT in any possible order does not change this :(
The VT100 shows only:
I tried the suggestion from Don with the M9302 in the last slot of the
11/44 backplane. To my surprise, when you hit ^P, the system prints a
new "(Program)" line and the cursor (_) moves to the next line.
So, now I am thinking ... a wrong/dead terminator on the RL02 drive,
can it have such an effect that through the RL11 controller the bus hangs?!
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