< This might be a bit of an odd question, but can anyone point me in the < right direction to find info on theory of operation of a front panel? < have a z80 based computer which I built a few years ago (wire-wrapped) < which uses an eprom for program storage. I would like to add a front < panel (switches and lights) to it to get better aquainted with the old w Find a copy of bursky's book The S100 Bus Handbook. Front pannels don't work with Z80s if... DRAM depends on the z80 for refresh. Reason is the stopped state is a very long wait state. theory wise it's farly simple but there are a lot of repeated circuits as you have to buffer everything and do some work centered around the CPU timing. Allison