Hi,

The heart of my current project is a 80C32 uP, with 64kB of external ROM and 8kB of external RAM.

I'm currently facing problems having an eprom simulator to work fine (which is not the case with my previous version, that had only 2kB of external RAM). Maybe I will address some questions in the future regarding this problem, but for now I have the following specific question.

When I don't provide an EPROM and don't provide a RAM chip (so, the processor board only contains a 80C32 processor, the EPROM and the RAM sockets are empty) and I power the processor, the oscillator is working nicely (measuring pins 18 and 19 on a 40-pins DIL version). This is, in fact, the only 'activity' I would expect. However, next to this, I also see some activity on the RD and WR lines (pins 17 and 16).


Why is this? Since the 80C32 is ROM-less and there's neither an EPROM in the EPROM socket, nor a RAM in the RAM-socket, where does the 80C32 get the instruction to fetch external data?

Or is their maybe some 'micro code' running, even on an 'empty' 80C32?

Who can explain me what a EPROM- and RAM-less 80C32 does after it has been powered up?

--Geert