PDP-11/05 microcode dump?

[Christian Corti]

On Sat, 7 May 2016, Mattis Lind wrote:
> What are the failure modes of PROMs?

I had a PROM fail on the 11/45 CPU board. This PROM is responsible for the 
Conditional Codes handling. There was one output that had failed. I think 
that the output drivers may fail, because I was able to temporarily fix 
the problem by adding a pull-_down_ resistor to the (open-collector) 
output. That fix was unstable of course, and I ended up in replacing the 
PROM with a GAL (ugly fix because the pinout doesn't match well, and there 
is no space for a nice adapter solution)

Christian