IBM 310ED - Manual (Page 91)

Rear View
1 I/O door
2
Power jack
3 Security keyhole
4
Microphone-in jack
5 Line-in jack
6
External diskette drive connector
7 Line-out/headphone jack
8
Serial connector
9 Parallel connector
1
External display connector
11
External input device connector
ThinkPad 310, 310D, 310E, 310ED (2600) 67