They should. I saw you were dabbling in repros so I won't be talking out of school. From the 8k up to 64k chips, they follow a JEDEC standard pinout. So the EPROMs and the Nintendo Mask Roms are perfect fits. Up from 128k to 512k (or even 4 Megs I think for SNES. They actually use 8bit chips, not 16), their Mask Roms change the pinout of the address lines a bit. Again for more copy protection, so you cant just suck the data off of it easily unless you know the pinout. You can get away with using a special Hitachi chip EPROM thats a direct drop in for 128k PRG (I dont think it works for CHR) but for 256k you WILL need to rewire. IIRC there was a program that allowed you to address swap some of the legs, so you had less wiring to do. MAYBE theres better tech out there to do that? OR they just threw in any EEPROM in there. Who knows.