The Keyboard Controller Interface, 0x60/0x64

The original IBM PC (1981), and its immediate successor, the IBM PC/XT (1983), had keyboards limited to unidirectional communication: data flowed one-way from the keyboard to the motherboard. With the launch of the IBM PC/AT (1984), IBM added a keyboard controller, the venerable Intel 8042. The Intel 8042 implemented a bidirectional keyboard controller interface based on I/O ports 0x60 and 0x64 ,…