Game Pack Software (GPS code) on NES games

Splash

Can someone help me out with a few informations about the GPS code games? I bought a bunch of games and there are some GPS games in it for example Super Mario Bros 3. Are these games rar? What is the story behind these GPS code games?

Marijn

There was a topic about that: http://www.nintendoage.com/forum/messageview.cfm?catid=5&threadid=454&keyword1=GPS code

Splash

Thanks a lot man, that is what I searching for.