SMB: PPU memory?

johnnie · Post by **johnnie** » Wed Nov 21, 2007 8:57 am

OK, I have a basic 6502 CPU up and running and am now starting work on the PPU. My problem is: what does its memory contain after loading the ROM? I know what's supposed to be in there, but where in the ROM am I supposed to find it?

Disch · Post by **Disch** » Wed Nov 21, 2007 9:18 am

Super Mario Bros has 32K PRG (2 banks) and 8K CHR (1 bank). If your ROM does not indicate it has CHR-ROM, your header is either bad, or your ROM is bad, or you're reading the header wrong.

In any event... typically when games do not have any CHR-ROM, you give them 8K CHR-RAM at ppu$0000-1FFF

johnnie · Post by **johnnie** » Wed Nov 21, 2007 9:33 am

Hmm.. Turns out there was a small bug i nmy ROM reading routine. It indeed does have one CHR bank, thanks