Testing Famicom expansion port compatibility

I've read that some non-Japanese games don't read the controller correctly and therefore don't work with the Famicom expansion port, like "Battletoads" and the European version of "Solar Jetman".

How can I test this in an emulator?
What do I have to do, for example, in fceux or Nestopia, so that the input for "Battletoads (U)" doesn't work while the input for "Super Mario Bros. (JU)" still works?

This way I want to see if my game does it correctly.

The Famicom "4 player adapter" option under input covers this. Controllers 3/4 should shadow 1/2 on any 2 player game that is correctly listening for Famicom. Nintendulator has the same option.

In 4 player games the game should distinguish 3/1 and 4/2 instead of combining them.

Note that the famicom 4 player is different than the "four score" adapter for the NES, which does not use the Famicom expansion bits at all.


On the subject of Battletoads, the Japanese version does correctly listen to the expansion bits, it's just the other regions that don't. The Japanese version was made last, and it had many revisions, bugfixes, and changes to level design (made it easier).

Do you mean in fceux or in Nestopia?


So, is this only an issue for games that have more than one player? Because my game is one player only. And "Solar Jetman" seems to be one player only as well.

I thought I could create a constellation where one of those games can't be controlled at all.

FCEUX or Nintendulator. I don't know about Nestopia, you can test it if you want to know.


No, I was simply contrasting 2 player and 4 player. 1 player games should be listening to 1 and 3 if intended for Famicom.

The entire issue is just that Famicom controllers can't be removed or replaced, so if you don't support the expansion controllers you're putting an imposition on Famicom users that have a broken gamepad or otherwise would prefer to use a different controller (e.g. maybe you don't want to sit 2 feet from the console). If the game isn't intended for Famicom it's not an issue at all, which is why plenty of Nintendo licened games that weren't released in Japan don't do it.

O.k., I got it now. Thanks.


My game is of course supposed to be playable on every console. I also let FamiTone adjust the sound for PAL consoles.