IBM PS/1 - Page 240

Serial Ports
Pin Signal Name I/O
1 Data Carrier Detect I
2 Receive Data I
3 Transmit Data O
4 Data Terminal
Ready
O
5 Signal Ground
6 Data Set Ready I
7 Request To Send O
8 Clear To Send I
9 Ring Indicator I
Mouse
Pin Signal Name I/O
1 Data I/O
2 No Connection
3 Ground Power
4 +5 V dc Power
5 Clock I/O
6 No Connection
Keyboard
Pin Signal Name I/O
1 Data I/O
2 No Connection
3 Ground Power
4 +5 V dc Power
5 Clock I/O
6 No Connection
5-22