I think what paige means is that when you're in Mame, go to the TAB menu, at the top of the list is "Input (general)". Enter that menu, scroll down a ways, and at some point you'll see "P1 Left/Up, P1 Left/Down, P1 Right/Up, P1 Right Down" etc. These are inputs for games where you use dual joysticks per player (Robotron, Battlezone, etc.) The "P1 Left/Up" etc is for mapping Player 1's LEFT HAND joystick. "P1 Right/Up" etc is for setting Player 1's RIGHT HAND joystick.