I've finally gotten my emulator to work with a few Mapper 0 games, especially those without any scrolling.. However, I'm still having problems getting Super Mario Bros to work.
I can display the title screen, the music works fine, the play field is scrolled correctly (except for the status bar), but Mario will just take off and fly through the top of the screen when I press jump.. Also, all the enemies fall off the bottom of the screen. What could be causing this strange collision detection behaviour?
I haven't implemented the Sprite #0 hit flag correctly yet, but that's just for the status bar on top, right?

Another question: I've run the NEStress rom, and it gives an error on 'Use 2002/5 to set address'. What does that mean, and what is the expected behaviour? It's not mentioned in the info file.