MAMEWorld Forums - News - Re: Team Europe: PICO Game dumped and MCU confirmation

> your statement would also mean you have to "mark" every other rom-dump also as "NOT
> GOOD"...as long as you do not have a second dump from another board and another
> dumper! Even if the game is running in MAME or on real Hardware with the dump...
> as it could also be possible, that an normal eprom get's a bad bit on an area which
> is for example normally empty and not used...

It's not as bad as that - if you work on the assumption that the programmer was sane you can spend some time analysing a program to determine whether it's good. I'm very confident that the MCU dumps for Bouncing Balls, Joshi Volleyball and Street Fight are perfect. It helps that with Joshi Volleyball the MCU checksums program space on boot, so many errors would be detected.

I'm very confident that all but one bit of the MCU dump for Bad Dudes is good. That one bit is in the implementation of a program checksum command that the game never uses. It could be an original bug that prevented them from using the command in the game, but given how obvious the bug is and that it's an EPROM part so the cost to fix it would have been low (compared to redoing a mask ROM MCU), I think it's more likely to be a single bit error in the dump.

The Amiga 1200 keyboard MCU dump that we have passes a 16-bit program checksum, but does contain a bad bit that means it only verifies one magic number rather than several when deciding whether a reset was caused by NCOP. Since it passes its checksum, I assume this is an original program bug that they didn't notice/fix because it doesn't prevent it from working.

Verifying a program like this is a lot of effort, so we're not going to be doing it for every MCU (and I definitely don't have time to do personally for every MCU), but it's definitely possible to do, and allows issues to be found in areas that aren't used by the game.