"NES Kid" wrote:I think SMB2(j) was an FDS only release, and since the the FDS had more ram and other things, the NES is technically incapable of running it except through the FDS.
That seems unlikely. By and large, its looks so similar to Super Mario Brothers that I'd be surprised if it's not just a modified verision. Besides, it's not like other FDS games weren't released on cart (Metroid was an FDS game in japan, wasn't it?). It MAY require modification of the ROM, in order to make it conform to a mapper, but I'm sure that there are boards that could host the game. Some of the later NES games had much bigger requirements than FDS games, I'm sure.
As to the theory behind how you do it, it's fairly simple, but I've never done in so it may be a lot more difficult in practice. Basically you locate a game with the same board type and mapper as you want to reproduce, then unsolder the PRG and/or CHR roms, and replace them with eproms which burnt. For simple boards, that's all that's needed. For some of the more complex ones, you may need to rewire the board/modify the chip somewhat before installing it, though the exact procedure depends on the board.
Regrettably it's not just a case of burning a ROM to a chip. I believe a ROM file consists of binary dumps of the contents of any ROM chips inside the NES cart, along with a header that contains information about the game, so that the emulator knows which mapper to emulate and at which memory address inside the file to find each "rom".
Thinking about it, this topic might be better in the "hardware" forum.
