I saved the ROM loaded in the Sound Cartridge with MGSAVE then compared it with the original. Only last 2kB (800h bytes) are different. Sofarun doesn't seem to load the Rom until the end, 2kB are missing.
I do the same thing with King Valley 2 and both are same. No part is missing.
The last page of a 512KB ROM is #3F, and that is the "magic" page in which SCC registers are mapped (see http://bifi.msxnet.org/msxnet/tech/soundcartridge). There's nothing special with page #3F in SofaROM, and the same function is used for OCM (on which Metal Gear 2 works). So it could be the cartridge is flashed correctly, but the "mode" is different and yields a different dump...
GDX, if you do a dump after flashing with the other tool, do you have the same result ?
Also, if the SCC registers are always mapped in page #3F, that could be a problem to load bigger (ASCII16 or ASCII8) ROMs - they could be "corrupted" at the registers location in page #3F ? I'll try to have a look if I can get myself a sound cartridge like yours (or maybe that could be reproduced on openMSX ?).
Ah darn, the size of the SCC sound cartridges can't be expanded in openMSX. Increasing this line in scc+.xml or scc.xml
mem base="0x4000" size="0x8000"
generates this error:
Fatal error: Error in "scc+" extension: Invalid memory specification for device Konami SCC+ Cartridge with expanded RAM should be in range [0x0000,0x10000).
Looks like ROMLOAD tries to patch the ROM when it's not required (that 32 00 80 in Metal Gear 2 is probably data and not code). SofaROM only apply patches if needed, so there's no patching for Metal Gear 2 when flashed on SCC compatible device (the AI parameter has no effect in this case).
My understanding so far is that :
* Flashing of the ROM is correct (page 3F is special and causes a different result when dumped but might be OK when used inside the game). loading ROM with ROMLOAD would not work if that was not the case.
* There's a compatibility problem with Nextor and the extended SD Snatcher cartridge.
I'll try to reproduce that with the latest openMSX.
