I looked up the EPROM...it a AT27C256R. The data sheet says the read access time is 45ns. I also found in the 80390 user's guide that at reset the MPU defaults to adding stretch cycles to its MOVX memory, to allow for slower RAM. However it only mentions that this applies to data memory. I'm not sure how code fetches are delt with. The hardware guy I'm working with selected the AT29C256 as an equivalent reprogramable chip. Its read access time is 70ns. I assumed he knew what he was doing. Do you think this will work?