Marco Antonio Simon dal Poz <[EMAIL PROTECTED]> wrote:
> > >But Hinotori is a 128kb game. So, why do you need VRAM?
> >
> > The ROM is 128K and it also needs some RAM (probably 16K) to run.
> > And ROM pages are 8K in size, mapper pages 16K. This means that sometimes
> > you need to duplicate ROM pages in the mapper to allow all combinations
> > used by the game. Example: ROM page 0 and 4 are used together, just as ROM
> > page 0 and 13. In the mapper you'll need 2 pages (32K) for those three 8K
> > pages (24K).
>
> If you have 256kb of RAM, there's enough space to do all the necessary
> combinations. Or am I wrong?
Suppose you have 128KB (1 Mbit) ROM = 16 blocks (0-15) of 8 KB.
If you want to have all combinations with block #13 in the lower half
of a 16K page, than you need to store combinations 13+0, 13+1,
13+2,....,13+15 = 16 mapperblocks needed for instant retrieval.
The same for block 0, 1, 2, etc., and combination of blocks 13+2
needs its own mapper block next to combination 2+13.
So you would need 16 x 16 = 256 mapper blocks = 4 MByte mapper for
this.
(damn, this could work! does anyone feel like writing a loader for
this, so that you could run most or all 1 MBit Konami's just like
that, if you happen to have a 4 Meg mapper?)
2 MBit ROMs = 32 blocks -> 32 x 32 mapper blocks = ....
(slotexpander filled with 4 mappers of 4 Meg each)
Greetings,
Alwin Henseler ([EMAIL PROTECTED])
http://huizen.dds.nl/~alwinh/msx MSX Tech Doc page
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