The interface box, mounted on the cabin floor alongside the recorder provides the interconnections between the recorder, control unit, sonar system and ICS system. Located on the front panel are three connectors and on the rear panel three connectors. Two connectors are for sonar, one for control, one for audio monitoring, one for sonar signal input to the recorder and one for control and sonar signal output from the recorder. A two position toggle switch, located on the rear panel shall be selected to the 13B position for operation with the sonar system.