IBM 770 manual Keyboard/Mouse Connector, Signals, System Board

Keyboard/Mouse Connector

Each ThinkPad computer has a keyboard/mouse connector, where the IBM mouse, keyboard, or numeric keypad is connected.

Signals

The keyboard and mouse signals are driven by open-collector drivers pulled to 5 V dc through a pull-up resistor. Figure 2-1 lists the signals.

Sink current			1 mA			Maximum
High-level output voltage			5.0	V	dc	minus pullupMinimum
Low-level	output	voltage	0.5	V	dc	Maximum
High-level input voltage			2.0	V	dc	Minimum
Low-level	input	voltage	0.8	V	dc	Maximum

Figure 2-1. Keyboard and Mouse Signals

Connector

The keyboard/mouse connector uses a 6-pin, miniature DIN connector.

6 5

43

2 1

Pin	I/O	Signal Name
1	I/O	Mouse	Data
2	I/O	Keyboard		Data
3	–	Ground
4	–	+5 V	dc
5	I/O	Mouse	Clock
6	I/O	Keyboard		Clock

Figure	2-2. Keyboard/Mouse			Connector		Pin	Assignments
Note:	The	maximum	current	for	+5	V	dc (pin 4) is 0.5 A for both the
	mouse	and	the numeric		keypad.

2-4 System Board