Communications: electrical – Audible indication – Percussion-type sound producer
Patent
1985-10-29
1988-04-19
Caldwell, Sr., John W.
Communications: electrical
Audible indication
Percussion-type sound producer
340365R, G06F 302
Patent
active
047393106
ABSTRACT:
A keyboard control system is comprised of a key matrix circuit and a keyboard controller. The key matrix circuit includes scanning lines and return lines, these lines being connected to keys on a keyboard, a decoder for transferring a scanning signal to each scanning line, and a receiver for receiving a return signal as a scanning signal returned through a return line and by the depressed key. The keyboard controller generates a key matrix code corresponding to the depressed key on the basis of an address of a scanning line to which the scanning signal is output and an address of a return line through which the return signal is input. The keyboard controller stores the generated key matrix code into a keyboard buffer memory. When the depressed key is a special key for display, the keyboard controller generates a key matrix code in response to the key depression and displays predetermined data on a screen. Key release of the key is detected and, upon detection of the key release, a key release status flag is added to the key matrix code in the keyboard buffer memory, thereby invalidating the key matrix code and extinguishing the data display.
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"Direct Diagnostic of Keyboard Hardware on a Personal Computer"--IBM Technical Disclosure Bulletin--vol. 28, No. 2, Jul./1985--pp. 758-759.
W. L. Holloway, II--"Elimination of False Data Caused Bounce of a Switch-Contact Keyboard"--IBM Technical Disclosure Bulletin--vol. 27, No. 5, Oct./1984--pp. 3173-3174.
Caldwell Sr. John W.
Fatahi-Yar Mahmoud
Kabushiki Kaisha Toshiba
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