Are there major differences between disk system and nes code?

[Ar8temis008]

I want to asm hack Doki Doki Panic and make the player accelerate when the b button is held down. Would it be any different from hacking an nes game?

My idea is, if there aren't major differences, find out how the b button run works in nes smb2 and simply add it over to the fds game.

[Disch]

Would it be any different from hacking an nes game?

Not really, no.

The FDS works mostly like any other mapper... the main difference is that bankswitching (or rather, the FDS equivalent of bankswitching) is REALLLY slow.

[KingMike]

The difference is that the data is loaded from the disk into the FDS' RAM.
Once it's in RAM, then yes it functions essentially the same as NES.