> Is this the type of thing that makes Konami such devious hardware designers?
Generally what makes them devious is that all of their custom chips are *extremely* flexible. The K056832 has 16 physical VRAM pages logically organized in a 2D grid, and you can specify for each page of a tilemap which physical VRAM page it is - they don't have to be contigious or anything, and in some of the more creative games they aren't :-) No other hardware is that flexible, including ST-V.
> * Maybe one way to handle this is to have two seperate memory maps and switch between
> them based on bit 0002 and 0020? Gonna' look to see if that's possible...
In this case, you're best off just defining each of the ranges (6000-6fff, 7000-7fff, 8000-fbff) as a READ32_HANDLER/WRITE32_HANDLER and auto_malloc()'ing the necessary RAM space. (MESS does it in cases like the Apple Lisa where there's a custom MMU (original Apple VLSI, not the PMMU Motorola sold for the 680x0) between the 68k and the bus and so nothing has a fixed physical address, and Sega System 16/18 are also similar :-)
Edited by R. Belmont (05/13/06 11:15 PM)
|