KB and Mouse Connectors


Location of Keyboard Connector


Location of Mouse (pointing device) connector.

ps2mouse.zip IBM PS/2 Mouse Program Diskette Ver 1.00 

The keyboard and auxiliary-device connectors are 6-pin miniature DIN connectors. The signals and voltages are the same for both connectors.

The following figure shows the pin numbering and signal assignments for the auxiliary-device connectors.

Pin
Signal
1
Data
2
Reserved
3
Ground
4
+ 5 V dc
5
Clock
6
Reserved

Signals
The keyboard and auxiliary device signals are driven by open-collector drivers pulled to 5Vdc through a pull-up resistor.
Sink current Max
20mA 
Hi-level output V Min
5.0 Vdc minus pull-up 
Low-level Output v Max
0.5 Vdc 
High-level input v Min
2.0 Vdc 
Low-level input v Max
0.8 Vdc 

Pin numbering and signal assignments for the keyboard connector plug-

DIN Pin
Signal Name
KB Pin
1
+KBD DATA
B
2
Reserved
F
3
Ground
C
4
+5.0 Vdc
E
5
+KBD CLK
D
6
Reserved
A
Shield
Frame Ground
Shield


Serial Mouse Conversion?
   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 worser - 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 conversing serial mouse to PS/2 and vice versa.
   The "dual mode" mice have an automatic logic detection and sort of adaptive interface electronic, which detects whether the mouse is attached to a serial port or a PS/2 port and set the output drivers accordingly.
   As you can see from the above: it is not enough only *physically* changing the plugs.

PS/2 Mouse Versions
From Fred Mau

   Best as I can tell, IBM had five distinct species of Rattus Armonkus in the PS/2 world: (Not to mention all the clones).
- The original ugly wedge-shaped PS/2 mouse
- Early oval-shaped mouse. White body and white buttons.
- Later oval-shaped mouse. White body and brownish buttons.
- A smaller black mouse to be used with the CL57and N51 and thinkpad 700 and
720 laptops.  Lower voltage than a regular mouse, not interchangeable.
- The current IBM mouse, OEM'ed  by Logitech. A more ergonomic oval.

   Best as I can tell, all the PS/2 mice (except the minnie mouse for early thinkpads) are interchangeable, with one notable exception:  If you have an 8516 Touchscreen monitor, the touchscreen cable plugs into the mouse port and the mouse plugs into the monitor, but it will ONLY work with the original ugly mouse or the early oval mouse with white buttons. It won't
work with the later oval mouse with brown buttons or anything newer.  I have no idea why, but apparently something changed in the mice.  It's something to keep in mind if you ever happen across an 8516.

From Jim Shorney:
   Side note: I seem to have an oval variation you didn't mention: white top, white buttons, brownish bottom, 33G5430/33G5410/FRU33G5420.
   BTW, have you seen the IBM memo on mouse ball replacement?  Hilarious.

From Carroll Bloyd
   And there's the track-ball/mouse combination (P/N 1397040) sold for use with the L40 SX laptop.  Big ugly thing--the mouse side of the device looks like a larger version of the original PS/2 mouse.

Resolution Increase
From Aron Eisenpress
   I'd like to point out one substantive change in the IBM PS/2 mice, which happened around the time of the two-tone-topped ones: the resolution increased from 200dpi to 400dpi (and noticeable if you swap mice around as the speed of the cursor will change!)...

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