For example, if Player 1 moves UP-'''and'''-RIGHT then UP and RIGHT are shortcut with each other. In result, without the diodes, Player 2 would automatically move UP-'''and'''-RIGHT whenever trying to move UP-'''or'''-RIGHT.
The diodes are, of course, needed only on one connector (eg. Joystick 2 only). The schematics with diodes on both Joystick 1 and 2 connectors are a bit overcomplicated. Normally only 5 diodes are required (or 7 when implementing the extra fire buttons).
== See Also ==