PS2 MOUSE PORT

11/27/99

PS2 Mouse Port: Technically this is called the PS/2 Auxiliary Device Port. It is associated with the keyboard controller and generally utilizes a 6 pin mini-DIN connector exactly like that for the PS/2 keyboard. This ingenious arrangement ensures that roughly half the users will plug the keyboard and mouse in backwards.

The pinout for the PS/2 mouse port is not especially easy to find. It is pin 1 = data, pin3 = ground, pin 4 = +5Volt DC, and Pin 6 = Clock. The data is a TTL compatible data string clocked by the clock line. It is synchronous. This interface is pretty much totally incompatible with the asynchronous bipolar signaling used by serial mice although some vendors manage to produce mice that will somehow run off of either interface.

The PS/2 Auxiliary Device Interface uses Ports 60-65 and IRQ12 to communicate with the mouse. It does not conflict with the normal serial ports or their IRQs and therefore allows a PS/2 mouse to be used to free up a serial port. The PS2 mouse should be turned off in the BIOS if a serial or USB mouse is to be used, and especially if another device is to be placed on IRQ12.

For programming data, search the World Wide Web for documentation for the Linux psaux program.

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