I've been at this for the last week or so, and I finally got a .NES file that does something. I've created a map editor and a metatile generator, and a NES rom that shows the first part of a map. I made it so that it can load a column of metatiles in at a time. There's a lot of temporary code in there, and other nonsense, but if anyone wants to give it a look go ahead. And if you feel like it, let me know if I'm doing anything seriously wrong.
http://www.yibbleware.com/nes/cartlemmy-test.zip
EDIT (Oct 14, 2010 @ 10:35AM PDT):
I just realized that I can set the PPU to increment by 32 instead of 1 by writing columns, that would make my code a lot more efficient. I discovered that setting bit 2 of PPU register $2000 will increment it by 32.
Oh, and I know this demo is incredibly boring... I'm just happy that I made something work.
http://www.yibbleware.com/nes/cartlemmy-test.zip
EDIT (Oct 14, 2010 @ 10:35AM PDT):
I just realized that I can set the PPU to increment by 32 instead of 1 by writing columns, that would make my code a lot more efficient. I discovered that setting bit 2 of PPU register $2000 will increment it by 32.
Oh, and I know this demo is incredibly boring... I'm just happy that I made something work.