OPERATION SYSTEM, GAME SYSTEM, AND GAME CONTROLLER CAPABLE OF IDENTIFYING CONNECTED DEVICE WITH SIMPLIFIED SCHEME

A connected device (200) includes a first battery (V2) for supplying electric power to a game controller (3), a first terminal (201, 201C) electrically connected to the game controller, and a resistor (R2) connected to the first terminal. The game controller includes a control circuit (102, 103, 32), a second battery (V1) for supplying electric power to the control circuit, a second terminal (42, 42C) electrically connected to the connected device, a voltage detector (105) detecting a voltage value in accordance with a current which flows through the resistor when the first terminal and the second terminal are connected to each other, a discrimination unit (120) discriminating a device connected to the game controller based on the voltage value detected by the voltage detector, and a switching unit (SW1, SW2) making switching from the second battery to the first battery for supply of electric power to the control circuit when the device discriminated by the discrimination unit is the connected device while electric power is supplied from the second battery to the control circuit.