Method to Provide Low-Cost Keyboard Support
Original Publication Date: 1986-Jul-01
Included in the Prior Art Database: 2005-Mar-09
A method is described which provides a unique way to lower the power drain and product cost of a Personal Computer (PC) by moving the keyboard processing inboard into the main processor and eliminating the outboard keyboard processor. To an application program the keyboard interface is identical to that of a PC with an outboard controller including the generation of a hardware interrupt 1 request when scan codes are ready in PORT 60H. A 16 position scan code queue is also provided to prevent keystrokes from becoming lost when keys are pressed when programs have level 1 interrupts masked. The described implementation is specific to the IBM PC family of products where the keyboard interface is provided at port 60H and a data ready level 1 interrupt request is generated to the main processor.