Going through our archives we discovered that it’s been almost ten years since we published an EPROM emulator. The version we propose in this article should meet today’s demands of hobbyists wishing to debug microcontroller systems based on an EPROM. We have chosen the 27C256 because it is cheap and currently the most widely used EPROM in the hobby area.An EPROM emulator is a development tool designed to facilitate code debugging and code writing jobs on circuits incorporating an EPROM (electrically erasable read only memory). An EPROM, as most of you will know, can not be reprogrammed before its previous contents has been erased through exposure to a certain amount of ultraviolet (UV) light. So, even for the smallest modification to the code in your EPROM, you need to do a complete eraseandreprogram cycle, which is tedious and costly given the time lost and the price of an UV eraser box.