It works! After a few consultations, I have my vintage 1975 SWTPc 6800 up and running! Well, I learned several things. First, if you are looking for a short, you have to have a very clean board. If there is lots of flux and junk, you can't see anything. So, I really scrubbed my MP-A (processor board) clean, which let me find a couple of tiny solder bridges. Second, suspect crazy connectors. This board has a weird "ZIF" socket for the processor, where it is easy for the pins not to make contact if they are not bent right. Third, it is always the weirdest extinct bus transceivers that go bad, since they are the most difficult chips to find. And finally, a cheap Radio Shack logic probe can "see" a lot of what you can see on an oscilloscope, if you listen to the tones carefully. The data train on reset makes a nice little set of beeps. When I heard it, I got goose bumps. Now, on to try and get some software running! Louis