Shift control system for keyboards

Details Shift control system for keyboards Shift control system for keyboards

1982-03-24

1984-09-04

Crosland, Donnie L.

Communications: electrical

Audible indication

Percussion-type sound producer

340365R, 340365E, 235145R, G08C 900

Patent

active

044700385

ABSTRACT:
A shift control system for keyboard having plural character keys and at least one shift key arranged in a predetermined key matrix and the positions of which are defined by respective matrix codes, including a keyboard controller under the control of a central processing unit for determining a depression of any of the keys of the key matrix. The matrix codes of the shift keys are predetermined and so identified. The key matrix is scanned and the matrix codes of any depressed keys are determined and compared with the predetermined matrix code of the shift keys. Keycodes are formed for each depressed key based on the matrix codes produced for the respective key and based on whether or not a shift key depression is determined.

REFERENCES:
patent: 3742137 (1973-06-01), Garland
patent: 3778819 (1973-12-01), Bhagawan et al.
patent: 3846758 (1974-11-01), Gosset
patent: 4121048 (1978-10-01), Deu Choudhury
Intel Component Data Catalog 1979; Numerical and Functional Indexes; Microprocessor Peripherals 8278 Programmable Keyboard Interface.

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