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Asure
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Reged: 11/29/04
Posts: 21
Loc: Nederland
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Interresting Taito F3 bug in MAME
03/31/17 09:33 PM


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?

Edited by Asure (03/31/17 09:51 PM)







Entire thread
Subject Posted by Posted on
* Interresting Taito F3 bug in MAME Asure 03/31/17 09:33 PM
. * Re: Interresting Taito F3 bug in MAME Haze  03/31/17 10:24 PM
. * Re: Interresting Taito F3 bug in MAME SmitdoggAdministrator  03/31/17 10:33 PM
. * Re: Interresting Taito F3 bug in MAME Haze  03/31/17 10:35 PM
. * Re: Interresting Taito F3 bug in MAME Asure  04/01/17 02:28 PM
. * Re: Interresting Taito F3 bug in MAME SmitdoggAdministrator  03/31/17 10:08 PM
. * Re: Interresting Taito F3 bug in MAME Asure  03/31/17 10:50 PM

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