Pinouts >  Keyboard, Mouse and other input devices cables and adapters scheme
This adapter will enable you to use a mouse with a 6 pin Mini-DIN (PS/2) connector to a computer with a 9 pin D-SUB (Serial) connector. This requires that the mouse handles both protocols. A mouse like this is sometimes referred to as a combo-mouse.

The Serial Mouse uses a RS-232 style interface with -5 to -12 VDC as logical 1 and +5 to +12 VDC as logical 0. The PS/2 mouse interface is a TTL-style interface, which uses 0 - +2 VDC as logical 0 and +3 - +5 VDC as logical 1.

In addition - and to make things worse - the RS-232 is an asynchronous interface, the PS/2 interface is a synchronous, where the data is sent along with a clock signal. It uses a simplified 4-wires serial interface with +5VDC (for the transceiver), GND, keyboard / mouse clock and keyboard / mouse data. The data and clock line can be used from the keyboard / mouse controller and the attached device as well following a particular handshake, which defines which is the active sender and which is the receiver. So: it is not *that* easy converting serial mouse to PS/2 and vice versa.

RS232 adapter that should work for Microsoft IntelliMouse:

PS/2 Pin RS-232 pin Description
1 1  
2 n/c  
3 3  
4 5  
5 7  
6 n/c  



The dual mode mice have an automatic logic detection and form of adaptive electronic interface, which detects whether the mouse is attached to a serial port or a PS/2 port and sets the output drivers accordingly.

  Mini-DIN D-SUB  
RxD 2 2 RxD
TxD 6 3 TxD
+5V 4 7 RTS


6 pin mini-DIN male (PS/2 STYLE) connector layout
6 pin mini-DIN male (PS/2 STYLE) connector
at the mouse
9 pin D-SUB female connector layout
9 pin D-SUB female connector
at the computer
According to 12 reports in our database (4 positive and 7 negative) this pinout may be incorrect.

Is this pinout
Source(s) of this and additional information: Hardware Book, Tomas Ogren, Thomas Eschenbacher
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