MAMEWorld Forums - EmuChat - Re: Interresting Taito F3 bug in MAME

> So, i have the single pcb versions of Taito Cup Finals and Super Cup finals. I
> remember these had 27C010. Noticed the Mame dump has 27C020 dumps for both cart and
> single PCB version. I dumped both the games, and all the roms match if i cut them in
> half. I put the roms back on the pcb's and play a test match of Cup Finals which
> complains about EEPROM but plays fine... after i reset it.. By the time i turn on the
> Super Cup pcb, this also complains and i realised i had swapped and put the roms in
> the wrong PCB.
>
> Not a big deal. Until Super Cup gets stuck in a reset loop and will not enter the
> game. I can 'push test sw' and watch it count down, but the game will keep resetting
> afterwards.
>
> I use the Mame debugger to figure out where the 'press test sw' message comes from,
> and patch out the code. Works in MAME with EEPROM data from Cup Finals. No more
> errors. Great!
>
> I put the modified rom set onto the single PCB, but this now shows a nice ROM ERROR
> and will not boot further. I spent some time figuring out the problem, and patched
> that also. (The game wants 0000 into 0x408108 after checking the roms. It skips the
> region byte..)
>
> Funny thing #1: MAME calculates this CRC as CF36 and the game does not throw a ROM
> ERROR. Nor does it seem to read the value at this location at any time after the
> check(?)
> So, MAME always generates a wrong checksum (CF36) but never throws a ROM ERROR?
> Wierd. A similar routine works fine in Cup Finals and several other games i checked.
> Not all games have ROM test btw (trstar, pbobble2 and tcobra2 for example do not seem
> to care at all..)
>
> Funny thing #2: Skipping the Rom error by stuffing 0000 into 0x408108 does indeed
> skip it on real hardware, but the reset loop is still present. (Both a proper F3
> motherboard and single pcb will not boot the game..)
>
> Bug: Mame F3 driver does not handle ROM ERROR for scfinals/scfinalso.
>
> Observation: ROM dump for scfinalso is overdumped? Maybe the 'orange' single board
> uses 27C020, but not the 'white' single board i have here.
>
> For giggles, i put the Super Cup Finals chips into a F3 cartridge and used a real F3
> motherboard as another test, and this also ends up in a reset loop. It will complain
> and tell you to 'press test sw', seemingly write to nvram, but end up in a reset loop
> afterwards.
>
> Question: Anybody have a real Super Cup Finals cartridge, which actually works on a
> F3 mother? Is the PCB different from standard? Does it use a different PAL perhaps?
> Maybe a suggestion to recover my SCfinals pcb?

I believe Super Cup Finals is a special case which also checks for a magic value in the EEPROM in order to boot, some kind of rom-swap protection they didn't use on anything else.