Thanks to all for the advice so far. I now have the terminal connection working again at least. I do this and get: 147470 @ Further iterations all result in: 173000 @ If I hit restart at any time after that there is a some disk activity and eventually and "&" prompt appears. The keyboard doesn't respond and nothing seems to happen in a reasonable time after that. I consulted the original owner who reports that it definitely went through a self test routine on the screen and did this before the linked PDP8 was started, so there's a hardware problem somewhere. Anyway I'm streets ahead with the info from Aaron Finneys scans which I will now study. I plan to reseat all the roms and cards and check all the jumper settings. Thanks all, Hans