Re: [openMSX-devel] Request for Comment: MSX cheat database format

[Alex W. <ale...@sc...>]

> > I also think that doing cheat-pokes always to 'Main RAM' is safer. But
> > how do we define 'Main RAM'? There could be extra memory mappers
> > inserted. I think the slotID of the 'main' memory mapper is stored
> > somewhere in the MSX system variables. But how to read those system
> > variables in a relyable way?
>
> There are a couple of heuristics we can use:
> - simulating the algorithm of the BIOS: largest mapper is made main RAM,  
> except on turbo R, where the internal mapper is always main RAM
If I remember well, it is a little bit more complex:

The MSX2 takes standard the first RAM slot, ignoring whether it is a mapper or 
not. If a MSXDOS2 cartridge is inserted, then the MSXDOS2 cartridge will 
search the largest mapper slot and select it.

The MSX2+ might take the largest mapper slot by itself (even without DOS2 ROM) 
but I'm not sure. Maybe it behaves the same as MSX2.

The MSX turbo R always takes the internal mapper (like described above).

I want to test the behaviour of MSX2 and MSX2+ with non-mapped RAM extension 
and with mapped RAM extension, with and without DOS2 ROM inserted. I have 
noticed that openMSX can be started with the option "-ext ram1mb" to insert a 
1 MB memory mapper. In which slot does this mapper go? Is there any means to 
insert a non-mapped RAM cartridge? E.g. a 64 kB memory extension?


Kind regards,
Alex