tepples wrote:
Some Super NES copiers are built such that if you plug another cart with the same chip into the back (e.g. Yoshi's Island or Doom), then the game you write to the copier will use that chip.
Actually, that isn't entirely true. The FX chip has pins connected directly to ROMs on the cart, so it is impossible for copiers to connect to these special chips via a donor cart. The only special chip that this actually works for is the DSP1 chip, which happens to be the most popular co-processor used on SNES carts. Actually most SNES games don't use any special co-processor. Anyway, if it uses a special chip that is not DSP1, then you can't play the game on a copier. CherryROM's hardware forum has a listing of carts that use special chips and the type of chip they use. Search those forums for that list, and you will see the relatively short list of games that don't work on copiers.
Even though 99% of all SNES and SFC games work perfectly on the better copiers (SF7, DX2), some of the best games use a special chip other than DSP1: Star Fox, Star Fox 2, Yoshi's Island, and Super Mario RPG are such games.