There are no microcoded diagnostics in the 11/34. The boot ROMs do contain minimal CPU and memory diagnostics. The CPU and UNIBUS have to be basically working for the boot ROMs (and the console emulator they provide via the console serial line) to work; ditto for PDP11GUI. Note that the console emulator will work without working memory, provided the correct boot option (console emulator without diagnostics) is configured on the card that holds the boot ROMs. You won't, of course, be able to load anything without working memory. And the Programmer's Console doesn't require working memory either, and a lot less of the CPU working - the CPU only has to respond to HALT requests from the console. (I had one /04 - very similar to the /34, uses the same front console - which didn't run because there was a bit stuck on in all the registers - but the console still worked.) It does require the UNIBUS not to be wedged, though. Noel