JPH0142013B

In a CMOS type input-output circuit having an input control circuit, an output control circuit, a buffer circuit, a CMOS output buffer circuit and an input buffer circuit, the input-output circuit being capable of bidirectional transmission of information between a data bus and an I/O port, improvements on the control circuit are embodied by selecting a gate circuit in the input control circuit corresponding to that in the output control circuit. The output control circuit is connected to the input control circuit and the CMOS output buffer circuit. The CMOS output buffer circuit is connected to the input control circuit and the I/O port. Upon inputting a signal to both control circuits, the output control circuit causes the CMOS output buffer circuit to be electrically floating; the input control circuit outputs a level fixing signal regardless of the logic level of the I/O port.