IBM PC Keyboard - Connection

Connection

System Connector Pinout Transmission Protocol Command Strings Image
PC 5-pin DIN

(DIN 41524)
"AT" connector

 1 CLK

2 DATA
3 -RESET
4 GND
5 +5V

 2 start bits,
8 data bits,
make/break bit (keydown/keyup),
1 stop bit

keyboard reset via pin 3 to ground

 Not supported
XT 5-pin DIN
(DIN 41524)
"AT" connector		 1 CLK

2 DATA
3 N/C
4 GND
5 +5V

 2 start bits,
8 data bits,
make/break bit (keydown/keyup),
1 stop bit

keyboard reset via sequence on DATA and CLK lines

 Not supported
AT 5-pin DIN
(DIN 41524)
"AT" connector		 1 CLK

2 DATA
3 N/C
4 GND
5 +5V

 1 start bit,
8 data,
1 parity (odd),
1 stop bit
keyboard reset via command string		 Supported
PS/2 6-pin Mini-DIN
(DIN 45322)
"PS/2 connector"		 1 DATA

2 N/C (or MOUSE DATA)
3 GND
4 +5V
5 CLK
6 N/C (or MOUSE CLK)

 1 start bit,
8 data,
1 parity (odd),
1 stop bit
keyboard reset via command string		 Supported
Later
PC compatibles		 4-pin USB
Type A connector		 1 +5V

2 Data −
3 Data +
4 Ground

 sync field plus
8-bit bytes as packets
(HANDSHAKE, TOKEN, DATA, Special packets),
least-significant bit first.		 Supported

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