Hello, this is what I found: These ROMS can be read on an EPROM programmer as an MC68766 part, as long as the programer strobes CS or OE when reading each consecutive address. Most will do that. They can be directly replaced with pin-compatible EPROM MC68766 or MCM68766C35 but these are obsolete though easily available as surplus parts for about 10 dollars each. The SCM90448C might also be a direct replacement. Modern EPROM 27HC641 aka M27HC641 can be used and is pin compatible, as long as you cook the data before burning, because A10 and A12 (if I remember correctly) are swapped. Hope this helps. Andrea