Memory mapped keyboard controller

Details Memory mapped keyboard controller Memory mapped keyboard controller

1990-11-09

1994-01-18

Yusko, Donald J.

Coded data generation or conversion

Bodily actuated code generator

Including keyboard or keypad

364189, H03M 1120

Patent

active

052802833

ABSTRACT:
A memory mapped keyboard controller within a peripheral controller for use in an Industry Standard Architecture (ISA) computer provides a method and apparatus for efficiently monitoring and reading a keyboard switch matrix. In a first mode of operation, the controller activates all the columns and monitors all the rows in the switch matrix to detect when any one or more of the rows becomes active, indicating that at least one key on the keyboard has been pressed. When any row in the matrix is detected as active, then the keyboard controller enters a second mode wherein it selectively activates individual columns and monitors the rows in the switch matrix to detect which row and column contain the activated switch. When the switch location is determined, this location is interpreted by the keyboard controller into a scan code for the ISA computer.

REFERENCES:
patent: 4266278 (1981-05-01), Ebihara et al.
patent: 4305065 (1981-12-01), Mogi
patent: 4591833 (1986-05-01), Ishii et al.
Microprocessor Peripherals UPI.TM.--41A/41AH/42/42AH Users Manual, Intel.RTM. Corporation, 1989.
80C51SL-AG Keyboard Controller, Intel.RTM. Corporation, Sep., 1990.
80C51SL-BG Keyboard Controller, Intel.RTM. Corporation, Feb., 1991.

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