Abstract: A keyboard having an encoder in the form of a microcomputer includes an automatic reset circuit and a key matrix circuit. The microcomputer constantly feeds a key scanning signal to the key matrix and to the automatic reset circuit. If a program used in the microcomputer gets out of control as by external noise, the key scanning signal is ceased. The automatic control circuit detects such stoppage of the key scanning signal that extends over a given period of time, and the circuit then supplies a reset signal to the microcomputer to automatically restart it from the beginning of the program.