Bubble Bobble in megaflashrom scc+ sd

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By Louthrax

Prophet (2406)

Louthrax's picture

22-12-2015, 20:50

Daemos wrote:

I do not know how the flashing tool detects the mapper type but thats where the problem propably is. So we need to find out how the flashing tool detects the mapper type. Where to does it read write and what does it do. From there its analyzing the differences.

The MFRSCC+SD code works fine on real hardware, so the detection is OK. It's just that openMSX does not emulate MFRSCC+SD perfectly I guess (checking the "ASCII8 mapper MFR switch emulation" would be a good start...)

By Manuel

Ascended (18233)

Manuel's picture

22-12-2015, 20:56

I'm a bit surprised that even on real hardware the mapper type is detected as "Unknown" and still it works!

Guillian: what mapper type is used when it says "Unknown"?

By Louthrax

Prophet (2406)

Louthrax's picture

22-12-2015, 21:28

Maybe it defaults to ASCII 8 on real HW (at power on time or after reset), and it defaults to another mapper on openMSX ?

By mars2000you

Enlighted (6014)

mars2000you's picture

22-12-2015, 21:36

But openMSX has a database that it first uses before eventually making an automatic detection.

The mapper is ASCII8 or Konami, it depends from the used rom.

Should this database not be used in the MegaFlashROM+SD emulation ?

By Manuel

Ascended (18233)

Manuel's picture

22-12-2015, 21:42

Bug: https://github.com/openMSX/openMSX/issues/991

Cause found and fixed :)

mars2000you: no, that database is for running ROMs: it tells the emulator what surrounding hardware it should create around the actual ROM chip (so yes, that's the mapper circuit). It's strictly necessary for emulation of bare ROMs, because the ROM format is only the ROM dump and doesn't contain this information (unlike on some other formats for e.g. the NES).
In case of MegaFlashROMSCC+SD, the actual MSX software (OPFXSD) decides the mappertype, as it needs to program the hardware (MFRSCC+SD) to go to the proper mapper mode. In this case it did decide for the right mapper type: ASCII8.

But there was a bug in the ASCII8 implementation of the MegaFlashROMSCC+(SD) in openMSX.

By Louthrax

Prophet (2406)

Louthrax's picture

22-12-2015, 21:43

mars2000you wrote:

Should this database not be used in the MegaFlashROM+SD emulation ?

Emulation just has to be fixed to match HW, I don't like too much an emulation feature that makes things work better on openMSX compared to real HW Smile

By Philip

Champion (379)

Philip's picture

22-12-2015, 22:01

Manuel wrote:

Bug: https://github.com/openMSX/openMSX/issues/991

Cause found and fixed :)

Thanks for fixing !

By Manuel

Ascended (18233)

Manuel's picture

22-12-2015, 22:07

Thanks for reporting (more or less) Smile

By Guillian

Prophet (3455)

Guillian's picture

23-12-2015, 00:20

Sorry for delaying... Nice to hear it is already fixed!

When OPFXSD can't autodetect the mapper it sets ASCII8 mapper.
The reason is that Konami and Konami SCC should be detected fine. Then the ROM probably is ASCII8 or 16. And since ASCII8 are more common...

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