Mike, you might also want to have a look at https://www.hpmuseum.org/forum/thread-15356.html For testing , I have used a regular EPROM mounted on an external PCB and connected it with a ribbon cable to the ROM drawer. There are ribbon cable - DIP connectors with thin pins, which can be used without destroying the sockets inside the ROM drawer. You should not use normal pin headers as these pins are too thick and will damage the sockets. Unfortunately, many replacement solutions use such headers. You can buy individual, thin pins, but these are relatively expensive (e.g. at Mouser). The height of a replacement should be similar to a normal EPROM, so a thin PCB with a flat SMC Flash RAM might be a viable solution. This will also require a programming adapter. On the other hand, 128 KB capacity is still rather limited - e.g. Turbo-C header files are too large to fit into one EPROM, even if compressed by removing comments and whitespace. However, it should be possible to link software over two 128K modules, as was obviously done with Word Perfect in the days (see the Portable Paper). This linking requires some modification of the FAT entries in the image files, which I have not yet tried. Martin