Importance

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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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First Claim