Abstract: A sequence display apparatus including a sequence control circuit, a cathode ray tube control device and a sequence display control device is disclosed in which a keyboard included in the sequence display control device is provided with logical function specifying keys for specifying one of a plurality of logical functions corresponding to such logical circuits as AND, OR and flip-flop circuits and a timer and with keys for inputting the names of input signals and the name of an output signal. One logic function, all of the names of the input signals and the name of the output signal are inputted as one set by the key-in operation, each of a group of command codes which are determined by the kind of logical function and the number of the names of input signals, is added to a corresponding one of the names of the input signals and the name of the output signal which have been inputted, to compose a logical operation program.