`Datach - Battle Rush - Build Up Robot` not work in FCEUX

Discuss emulation of the Nintendo Entertainment System and Famicom.

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krzysiobal
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`Datach - Battle Rush - Build Up Robot` not work in FCEUX

Post by krzysiobal »

There is one game called `Datach - Battle Rush - Build Up Robot Tournament (J)` (mapper 157 - BANDAI 24C02) out of those mysterious Datach cartridges. This game works in Nestopia but does not in FCEUX - it starts normally, but after creating robot, nothing more can be done - starting tournament or any other mode causes just BEEP sound of inavailability - here is movie:
https://www.youtube.com/watch?v=XkekbUXmHDY

I suspect the FCEUx hardware mapper implementation is not 100% accurate - probably the EPROM is not well emulated and the game might check for it (I even implemented it in VHDL omiting the EPROM part and it follows the same behaviour).

I posted the bug in FCEUx sourceforget, but meanwhile maybe somebody who has more in common with that mapper could help? The wiki description about this mapper about EPROM part is not clear, it says that there are 2 EPROMs but does not say which one is mapped when and whats their content.
lidnariq
Posts: 11429
Joined: Sun Apr 13, 2008 11:12 am

Re: `Datach - Battle Rush - Build Up Robot` not work in FCEU

Post by lidnariq »

With the Datach:
* All games have access to the 256B EEPROM that's on the main cart. But only one game is known to use it.
* A few games (one game?) adds a 128B EEPROM on the daughter cart. We don't know if any games set up the $8000-$8003 registers wrong such that it would pose a conflict to always emulate it.

Oh, and several games won't do anything at all without something implementing the barcode scanner.
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