Abstract: A recording and reproducing device of the invention comprises a first connector having a plurality of contacts and gate circuits for receiving signals from a computer body. The first connector is connected to the computer body and also to a second connector having a plurality of contacts. The second connector has first contacts grounded on the computer body side and a second contact to which a signal from the computer body is not supplied. The first connector has third contacts connected to the gate circuits and a fourth contact which is connected to the second contact in a first connecting state and is connected to the first contact in a second connecting state. The fourth contact is connected to the control terminals of the gate circuits.