SpritesMind.Net

The values you get when nothing is driving the CPU data bus. On the Genesis, this is typically the last value that the 68000 read and in most cases that will be a pre-fetched instruction word. Ah, so the 68k goes to read from somewhere, such as Z80 RAM, finds nothing because it can't actually acces...

I don't know, maybe it's because when you need to reset z80, /RESET must be asserted long enough while Z80 has control of the bus to be effective. I'm not sure if that's really needed though. Maybe it has something to do with the 26ms wait period for /RESET the sound programming part of the manual ...

1) Z80 /BUSREQ is not directly connected to 68k CPU, it is handled by a dedicated chip which handles most address decoding and will assert z80 /BUSREQ if access is done to proper 68k address range and proper 68k data line is asserted. 1. OK, that makes sense. I guess I'm just wondering why they dec...

Hey folks, total noob here. I'm learning Genny programming with EASy68K and MAME debugger. (Unfortunately, I don't have access to a real Gen/MD at the moment.) I've been following along with the Big Evil Corp tutorials (really nice work on those, Matt!) and MarkeyJester's 68k tutorials (also really ...