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
