System for selectively coupling trackball and mouse through a switch where input device provides coded signal to disable trackball while permitting signals from mouse

A system for enabling or disabling a first mouse device, comprising:

• a keyboard controller selectively coupled to said first mouse device or to an external mouse device and receiving a signal from either said first mouse device or said external mouse device indicative of movement;
• a keyboard coupled to said keyboard controller for transmitting to said keyboard controller an enable or disable signal said keyboard also providing to said keyboard controller input signals indicative of keys being depressed on said keyboard;
• a CPU coupled to said keyboard controller;
• said keyboard controller including an associated flag which is set or reset in response to said enable or disable signal from said keyboard;
• wherein said keyboard controller discards said signal from said trackball indicative of trackball movement if said flag is set, while transmitting to said CPU input signals from said external mouse device.

A system for disabling or enabling a trackball for a portable computer, comprising:

• a keyboard controller selectively coupled to the trackball through a switch for receiving signals therefrom and for generating signals indicative of trackball movement, and wherein said keyboard controller couples to said switch through a control line to control the position of said switch;
• a central processing unit coupled to said keyboard controller for receiving said signals indicative of trackball movement;
• a keyboard coupled to said keyboard controller for providing input signals to said keyboard controller;
• wherein said keyboard provides a coded signal to said keyboard controller to indicate that said trackball is to be disabled, and in response said keyboard controller prevents signals from said trackball from being received by said central processing unit by changing the position of said switch, while permitting said central processing unit to continue to receive input dignals from said keyboard.