Abstract: A polling system for use in an audio system in which a plurality of controllers for controlling a plurality of input/output devices of the audio system and a system controller for controlling the status of the plurality of controllers are connected via a bus line. In an initial polling operation upon power-up of the system, the system controller in order confirms the connection of the plurality of controllers to the system and stores the results of confirmation. When the absence of connection of the controllers is confirmed in the initial polling operation, the system controller further monitors the level on a transmission line provided in the bus line for transmitting a requesting signal from the plurality of controllers to the system controller, and performs the polling operation once more if the presence of the requesting signal is confirmed.

Abstract: An electronic unit operable in conjunction with a body unit and used by mounting it on an automotive vehicle. The electronic unit includes first and second connectors which produces a coupled-status signal when the electronic unit is coupled to the body unit and a decoupled-status signal when the electronic unit is decoupled from the body unit. A microcomputer is coupled to the first connector and is selectively placed to a start mode when the coupled-status signal is received from the first connector and to a stop mode when the decoupled-status signal is received therefrom. The microcomputer produces clock pulses when it is in the start mode and a stop signal when it is in the stop mode. A timer is coupled to the microcomputer and outputs a reset signal to the microcomputer when the clock pulses are not received for more than a predetermined period of time. The timer further inhibits the reset signal from being outputted when the stop signal is received.

Abstract: A multi-disk player is disclosed which comprises a housing, a play-back means provided with a turntable and disposed in said housing, a magazine arranged to be demountably mounted in said housing at a predetermined mounting portion and for accommodating and arranging a plurality of disks one by one, a disk conveying mechanism for selecting desired ones of said disks in said magazine one by one, and for conveying the selected disks onto said disk carrying surface one by one from said magazine and conveying into said magazine one by one from said disk carrying surface, and a clamp mechanism for clamping the disk conveyed on said turntable.