Martin Korth, the author of NO$GMB and NO$GBA, appears to have started on an emulator called NO$NES that aims to implement the virtual machine specified by this document. Can anybody find any differences in behavior between that document and what we know about the Famicom or NES?
I've already found one: the description of "Sprite 0 Hit Flag" ($2002.d6) fails to mention that it doesn't become set if the overlap happens either at x=255 or at x=0..7 (if either or both of the clipping bits of $2001 are 0).
The description of MMC3 IRQs in "Cartridge IRQ Counters" might be wrong.
I've already found one: the description of "Sprite 0 Hit Flag" ($2002.d6) fails to mention that it doesn't become set if the overlap happens either at x=255 or at x=0..7 (if either or both of the clipping bits of $2001 are 0).
The description of MMC3 IRQs in "Cartridge IRQ Counters" might be wrong.