Nice! I wonder why that opcode's not documented. Do you have any more info about the instruction set other than what's in the 1990 Sharp Microcomputers Data Book? I haven't been able to find anything.

I'm having some difficulty figuring out the Contra segment mapping. I built a rig to mount the LCD panels that has all 41 connectors pinned out, and I apply a 3V 100Hz signal to pairs of pins and note which segment gets activated. This worked well on Top Gun and TMNT, but it's activating multiple segments at a time with Contra. So I need to sort that out.