John,
Just reading the thread again and noticed you have a socketed 8085.
Have you tried pulling out pin 1 and connecting it to a 5Mhz clock from a function generator? The processor should take off running. If not, check the interrupt pins and pull out any that might be stuck. At this point the processor should just run unless it hits some halt command in ROM. You might pull the ROMs as well and see if the address/data line are running and ALE is latching addresses in U550.
Regards
