Multi-purposes keyboard interface

摘要

A multi-purpose keyboard controller includes a matrix keyboard control circuit, a serial keyboard control circuit, a PC/AT port control circuit, and an external interface for RTC control. These control circuits are coupled in parallel with the interface logic of the computer system and use the built-in SMI interrupt mechanism of the computer system for reading and writing the keyboard or capturing keypress events. Software BIOS setup is employed to select one of the keyboard control circuits for utilization with the particular personal computer with which the system is employed. The interrupt scheme used by the keyboard interface uses SMI interrupts to the processor and SMI based software routines to read and write the values to and from the keyboard, thereby eliminating the need for dedicating a special hardware interrupt level; so that the system remains compatible with the DOS PC/AT Port 60/64h software interface.