Ken, if you have some spare bandwidth I have some high-res decap photos from the chip in the Casio SK-1!
I worked on trying to reverse engineer the instruction set from that chip, but most of the code is in a mask ROM that probably needs some debug wires to extract.
I worked on trying to reverse engineer the instruction set from that chip, but most of the code is in a mask ROM that probably needs some debug wires to extract.