The NES game “Mike Tyson’s Punch-Out” uses a password system to allow players to continue from certain points in the game. Each password consists of 10 digits, each of which can be any number from 0 to 9. There are 2 kinds of passwords that the game will accept, which I’ll call “regular” and “special” passwords. Special passwords are specific sets of 10 digits that the game looks for and reacts to in a unique way when they are entered.
more here..........http://tomorrowcorporation.com/posts/retro-game-internals-punch-out-passwords
more here..........http://tomorrowcorporation.com/posts/retro-game-internals-punch-out-passwords