Numeric keypad integration system

Abstract

A system for integrating an external numeric keypad with a keyboard on a portable computer wherein the keypad communicates with the system BIOS through the keyboard. The keyboard includes 82 or 83 keys and an internal keyboard controller connected to a switch matrix. The controller repeatedly scans the switch matrix to determine if one or more keys has been pressed and generates scan codes for the active keys which are then output to the computer BIOS. The keypad includes 17 numeric and cursor control keys. The keypad is controlled by an internal keypad controller which is connected to a switch matrix. The keypad controller scans the keypad switch matrix to determine if one or more keys has been pressed and to generate scan codes for the active keys. The scan codes generated by the keypad controller are sent to the keyboard controller through an auxiliary port in the computer system. The keyboard controller converts the scan codes received from the keypad controller into switch locations. The switch locations are then converted into scan codes and sent to the system BIOS by the keyboard controller. An auto-sensing routine is further provided to detect the type of external device connected at the auxiliary port.