The PS/2 Adapter enables you to connect a PS2 device to the Arduino mainboards. With the help of PS2Keyboard library you can create the bridge between these PS2 keyboard and the Arduino. Standard PS/2 interface; Power Supply should be 5V DC; 4 screw mounting holes whose diameter is 2.2mm Interface： Control interface: A total of four pins (GND VCC DAT CLK) GND to ground VCC is the power supply DAT is data input and output pin CLK is the clock signal pin. PS/2 socket: Standard PS/2 interface. Mounting hole: 4 screw mounting holes whose diameter is 2.2mm so that the module is easy to install easy to combine with other modules.