I have a Sega System E, Fantasy Zone 2 pcb that runs the NEC MC-8123B which contains a battery. I'm guessing that it's dead and would like to know if it's possible to revive it with a custom ROM set and a standard Z80?
The NEC MC-8123B contains a Z80B CPU and a non-replaceable battery.I don't know if someone prepared a patched ROM set but it seems easy to decrypt and replace (at least on System16B).You should ask about Retroclinic and Junoman .