PDP-11/10 repair started

tony duell ard at p850ug1.demon.co.uk
Sun Oct 4 13:16:02 CDT 2015

> Some corrections to my post regarding the console LED behavior.
> Voltage levels on the CPU backplane are still good whne the 2 CPU boards
> are installed in the backplane, but the processor is not responsive to
> the switches on the console panel.

It's been a long time since I've been inside an 11/10 (that will change soon as I fix
the one damaged  by the idiot removal men,..) but just to eliminate the obvious
check that ACLO and DCLO are solidly high.

On a system like this I would always start by looking at the microcode program counter.
What state(s) is it in? If it is sequencing through states, does the sequence make any sense?
Does anything happen when you press LOAD ADDR (say)?

Maybe start from one of the switches like LOAD ADDR and see if it is generating the right
signals on the processor board.


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