On Monday 22 January 2001 20:20, you wrote:
> > What about Required=SCC ? I need to make some tests, but I believe
> > the game will not run if the SCC mapper is not present (by SCC mapper
> > I mean the bankswitch when you write 3F to the last bank register).
> > Even if the users wants to turn off SCC due to performance problems,
> > I believe the mapper still needs to be present, so the SCC must
> > have Required status.
Until recently, fMSX didn't support the reading of the SCC instrument data.
This broke SCC autodection algorithms, but all Konami games ran without
problems. Nemesis 3 will run with just the mapper description.
> SCC has two functions: sound processor and MegaROM mapper.
> It's necessary as a mapper, but not necessary as a sound
> processor (although it's recommended). I think it's weird
> to treat it as one sole thing. In a real cartridge, of
> course SCC is one IC, but these are two functions to be
> emulated. I don't know if I can make myself clear about
> this point...
The mapper and the sound part are not 100% independant: they share the same
address space. After all, the SCC is located in mapper page #3F. And its
instrument data is overlayed over the data in the ROM; in the Solid Snake
cartridge or a 512K ESE-SCC, you can witness that behaviour.
I agree that we should try to separate the sound part of the SCC from the
mapper part as much as possible. But it's not immediately clear where the
separation line is.
Bye,
Maarten
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