[CloudGamerX]

Hi,
i discovered this awesome port of Final Fight 3 on the NES just a few days ago. Granted, it uses the music from Mighty Final Fight, it still played great. When checking the mapper, it says that it uses Mapper 90. I was thinking of doing a reproduction cart of this game for myself, but i don't know if it would need to be hacked into an MMC3 mapper or not. And if it does, is it even possible? I am curious to know.

[Bregalad]

What you discovered is a Chineese pirate. It means it's a crappy game developped by crappy people randomly ripping elements of existing games, and putting a random title on it. You are wasting your time with this kind of games.

Pirated games often use very exotic mappers. However they can be mapper hacked just like any other non-pirate games, the fact it's a pirate doesn't change that.

[CloudGamerX]

I am aware it is a pirated game for the Famicom, but much like Pokemon Yellow or Final Fantasy VII on famicom, wouldn't it be cool to actually be able to put the ROM on an NES cart?

[KingMike]

From looking up the mapper 90 documentation on nesdev.com, it doesn't look like you can convert it to MMC3. Not without at least a real assload of effort.

Pokemon Yellow and FF7 use FlashROM (from what I've been told) so its possible to get a compatible cart and replace the ROM. Also, they use what seems to be a very simple mapper (in theory). (Again in theory) the only thing preventing it from being converted to another mapper is that they use bigger ROM than most mappers support.

[Satoshi_Matrix]

You need to understand basically NES games are divided into two chips PRG and CHR. PRG is the program data that holds the script, the rules for the game, basically, almost everything. CHR on the other hand is graphical data, sprites, tilesets and effects.

Each of the mappers were designed with maximum allotted size limits. MMC3 I believe has a maximum of 256 KB PRG, and 512 KB of CHR. Only one game used these maximum values, that being Kirby's Adventure.

That said, MMC3 was not the upper limits of storage. The largest game to use an official mapper was Metal Slader Glory for the Famicom, which maxed out the MMC5 with a 512 KB PRG and a 512 KB CHR.

On the NES, this was actually outdone, but only by the horrible unlicensed Action 512, which used a total 1,536 KB PRG and 512 KB PRG with a custom mapper made specifically for that "game". 

Most of the big Hong Kong Originals to come out over the past few years such as Final Fantasy VII use a custom Flash rom that combines PRG and CHR into one file. In the case of FF7 FC, that uses a 2048 KB PRG + CHR using mapper 90, which is similar in capabilities to MMC1.

[Revenant]

That said, MMC3 was not the upper limits of storage. The largest game to use an official mapper was Metal Slader Glory for the Famicom, which maxed out the MMC5 with a 512 KB PRG and a 512 KB CHR.

That's actually only half of the MMC5's maximum capacity for both PRG and CHR, though there certainly aren't any 2MB licensed games out there (and even the NES PowerPak, which supports the MMC5, doesn't support PRG or CHR ROM sizes larger than 512kb, unfortunately).