This section is added on  a PUBLIC DEMAND! This section explains the pinout descriptions of serial port again and also the PS2 mouse signal description and helps to make your own adaptor to connect PS2 to Serial port for Combo Mouse.

Very Important, Use following information on your own risk ;-)
Most mouses are either built only for PS2 or only for Serial ports. But some of the new mouses are manufactured to work on both ports. These mouses are called Combo Mouse and the appropriate adapters are supplied with the mouse when you buy it or can be purchased as an option or you can build one on your own.  Because of the nature of the ports the two kinds of mouses are not directly compatible. They don't send out the information in the same matter (different protocols) and don't use the same signal levels, PS2 mouses uses TTL logic signals (0-5 volts) and serial mouses use RS232 signals (typically +10 volts - -10 volts). When a mouse is built for operration on both ports, are setup with a DB9 pin used in serial mouses, these connectors have 9 pins and the serial mouse only uses between 5 and 8 pins. This leaves us with at least 1 spare line, this is the line that the PS2 data portion of the mouse will use for sending it's information. So now we can figure out that, the adapters are designed to work on a particular make and model and are not usually compatible with all other mouses. There are millions of Mouse Manufacturing companies is the world. Please do not ask me which make and model are combo mouse. The standard PS2 mouse does not use Pin 2 and 6 but the internal electronics in Combo Mouse are designed specially to use them to work on Serial port. That's Combo Mouse.

What about Logitech Mouse?
Ans: Until now the very important observation by us is that Logitech Mouse are NOT combo mouse. Therefore the Logitech Mouse made for serial port will only work on Serial port and for PS/2 will work only on PS/2.  In some countries there could be some combo models available but 99% of them are not the combo.

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2. Serial port Pin Description

For following all connections we may use these chart for transmission of Data via Serial Port. Please refer chart # 11 for DB25 serial port pin description on main page

Serial port
MALE DB9 Pin Serial port, as seen on PC Motherboard	FEMALE DB9 Pin Mouse Connector, as comes with Serial Mouse
We can see small Metal Pins Inside the Frame	We can see small sockets (holes) inside.

Pin Assignments for DB-9 (Same as Chart#12 on Main Page)

1	DCD	Data Carrier Detect
2	RD	Receive Data
3	TD	Transmit Data
4	DTR	Data Terminal Ready
5	SG	Signal Ground
6	DSR	Data Set Ready
7	RTS	Request to Send
8	CTS	Clear to Send
9	Ring	Ring Indicator

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3. PS2 Mouse Pin Description

FEMALE 6 Pin MINI-DIN PS2 Mouse Port, as seen on PC Motherboard	MALE 6 Pin MINI-DIN PS2 Mouse Connector, as comes with PS2 Mouse
There is a small plastic piece in the middle of the connector which helps us to determine the proper insertion but in many cases people try to insert mouse forcibly and the small and delicate pins are damaged.

IMPORTANT NOTE: These motherboard manufacturers are really funny people in the world. Many a times Pin assignments given to a specific unit is changed. May be they have their own reasons. I myself found following two different PS2 Mouse pinout signals from Motherboards, which I tried to find for a very specific problem. A new PS2 mouse which was working on my computer did not work on my clients pc, though the INTERNAL MOUSE PORT was the same, which was working on my pc without trouble. That clicked my sixth sense and I tried to find old motherboard manuals like my client had and to my surprise I found new set of pinout descriptions on it which are given below as follows

By saying Serial port to PS2 Mouse means you have to connect PS2 connector Mouse on DB9 pin Serial port on motherboard and for this you need following items

1. Female DB9 Connector
2. Female PS2 mini-din 6-pin Connector
2. Small cable with only 4 wires to solder

FEMALE DB9 Pin Mouse Connector, to connect on Male serial port on motherboard	FEMALE 6 Pin MINI-DIN PS2 Mouse Connector, to connect with Male 6 pin PS2 Mouse Connector

Now solder the pins as follows

DB9 Connector				PS2 Connector
-	-	-		1	-	Not Connected
2	RD	Receive Data		2	RD	Receive Data
5	GND	Ground for voltage		3	GND	Ground for voltage
7	RTS	Request to Send		4	VCC	+5 voltage  (max. 500mAmp)
-	-	-		5	-	Not Connected
3	TD	Transmit Data		6	TD	Transmit Data

The reserved pins which were not used on PS2 mouse connected on PS2 port as explained in PS2 Pin Descriptions are used here! So do not get confused that pin 2 and 6 which were not explained in PS2 pin description are used here. Combo Mouse is designed in such a way that they work normally on PS2 port but they can be used on Serial Port with this special DB9 to PS2 adaptor by using pin 2 and 6.

Note: In most cases this pinout should work. But there are some other unknown PS2 Mouse units which might have different pinout inside and this Converter may not work for those. You need to modify only PS2 side pinout for those PS2 Mouse to work on the Serial port. RTS Signal from motherboard contains sufficient voltage for powering up Mouse. But in some cases it might not work in case less power supply capacity. Latest Scroll mouse may misbehave as they may be made with different internal hardware and driver design.

5. PS2 to Serial Port Converter Adaptor (for Combo Mouse)

By saying PS2 to Serial port Mouse means you have to connect Serial Mouse on PS2 port on motherboard and for this you need following items

1. Male PS2 mini-din 6-pin Connector
2. Male DB9 connector
2. Small cable with only 4 wires to solder

MALE 6 Pin MINI-DIN PS2 Mouse Connector, to connect with Female PS2 Mouse Port on Motherboard	MALE DB9 Pin Mouse Connector, to connect on Female DB9 connector of Mouse

Now solder the pins as follows

	PS2 Connector				DB9 Connector
	1	Data	Mouse-Data		1	DCD	Data Carrier Detect
	2	--	Not Connected		2	--	Not Connected
	3	GND	Ground for voltage		3 + 5	TD + GND	Transmit Data + Ground for voltage
	4	VCC	+5 voltage  (max. 500mAmp)		4 + 7 + 9	DTR + RTS + Ring	Data Terminal Ready + Request to Send + Ring Indicator
	5	Clock	Mouse-Clock		6	DSR	Data Set Ready
	6	--	Not Connected		-	-	-

NOTE: 3+5 means solder pin 3 and pin 5 together. 4+7+9 means solder pin 4 , pin 7 and pin 9 together.

Please read the warning note on my main pinout page. I am not responsible if you mess up with your cable with wrong soldering or wire-crimping. Make and use at your own risk.