There is an HP book specifically on I/O interfacing to the 2100 (and 21MX) I/O bus. I think there's also an abbreviated chapter on it in a different manual. I'll see if I can dig up the name and if it's online anywhere.
I've restored at least five 2100's, and run a dual cpu 2100A & 2100S system regularly. I have never heard of nor seen a power supply failure on any of them. The power supply always came up with little or no pot adjustment, and nothing else required. I'd be surprised if your PS needed any attention unless they were under water. Debugging the memory section is a far different matter. It's far *far* easier to troubleshoot if you have a known working set. If not, it's very easy for boards to test ok and then later fail and then later test ok (bad upper section of a 16K driver, etc.). J
