KEYBOARD DEVICE

PURPOSE:To increase the groups of keys with no change of software by providing a logical circuit which relays the output signal sent from a controller when either one of ten keys is operating and switching the working mode of the controller. CONSTITUTION:A controller supplies the scan signals of L levels to terminals Y0, Y1 and Y6 successively and monitors the signals of L levels produced at the terminals X0-X7. In a normal display mode the KANA (Japanese syllabary) display control signal is turned into a signal of an L level. An inverter 19 turns off and LED21 showing a KANA display mode. When a key '0' is pushed among those ten keys 2, an OR gate 6 supplies a signal of an L level to the terminal X0. An interface detects that the key '0' is pushed from a fact that the terminal X0 is set at a signal of an L level when a signal of an L level is supplied to the terminal Y0.