Abstract: An audio/video recording and reproducing system having a discrete function unit such as tape deck, record player or tuner connected thereto includes a function selection circuit and a function specifying switch disposed in a main unit, such as a pre/main amplifier, and a control line, such as remote control line, for connecting the main unit and the discrete unit. By virtue of the function selection circuit, the selection of a desired discrete function unit can be carried out at the main unit. However, in addition to this, the system includes an arrangement for permitting selection of a desired discrete function unit at the discrete function unit itself, and, when this is done, for controlling the function selection at the main unit to select the output of the discrete function unit.

Abstract: In an audio recording and reproducing system comprising a combination of audio units including a record player, a tuner and a tape deck and an amplifier unit including a preamplifier, a function switching system comprises a control unit arranged in the amplifier unit including a signal selection circuit for selecting out one of outputs of the audio units to a speaker, a control circuit for controlling the signal selection circuit and function switches for supplying function selection signals to the control circuit, and control signal lines for coupling the control circuit of the control unit to the audio units. The signal selection circuit responds to the actuation of a start switch of the audio unit to assume the selected function mode through the control signal line and the control circuit and responds to the actuation of a function switch of the control unit to assume the selected function mode.

Abstract: A function presetting circuit for an audio/video stereophonic playback system for presetting a function and controlling operations by a microcomputer comprises a reset circuit for providing a reset signal to the microcomputer at a time of power-on, a delay circuit for receiving the reset signal and delaying the reset signal a predetermined time period, and a presettable function presetting switch connected between the delay circuit and a key input terminal of the microcomputer.