Gonna share my experience...the EPROMs that have the little window that require good ole Hawaiian sunshine or a UV eraser to blank them, my APU1 will not program them, however my Pocket Programmer doesn't have a problem with it. I've given up on those older EPROMs and recently only use the EEPROMs. Problem is unobtainable in a 24 pin which is a small problem. http://gearhead-efi.com/Fuel-Injecti...sion-(27SF512)