I started on a Mitsubishi MELPS 4 microcontroller family emulation core. Known games using it are AFAIK:
- Coleco Frogger
- Gakken Frogger (or is this the same rom as coleco version?)
- Gakken Amidar
- Gakken Jungler

Rik: do you know any other games using this MCU?

Also, this thing has an output-PLA similar to TMS1x series. I've read about someone(nickname: blanka) that decapped a Frogger MCU. Is the die picture online somewhere? And if so: more than just the ROM.