6 PIN MINI-DIN FEMALE (PS/2 STYLE) at the computer.
|4||VCC||Power , +5 VDC|
Note: Direction is Computer relative Mouse.
There used to be RS232 signals on pin 2 & 6 on some old mice. A mouse with RS232 & PS/2 signal used to be called a combo-mouse. 2 is RXD and 6 is TXD.