A telephone apparatus comprising:
- a keyboard including ten keys and symbol keys;
- a serial data generating circuit which generates serial input data corresponding to inputted keys on said keyboard in response to clock pulses;
- a key input signal generating circuit which generates a key input signal representing an input through a key in response to a signal from said keyboard;
- a panel substrate provided with said serial data generating circuit and said key input signal generating circuit and disposed at the side of an operation panel;
- a clock generating circuit which generates the clock pulses;
- a processor which receives the clock pulses, the key input signal and the serial input data, and outputs serial key data and control signals in parallel with the serial key data, wherein said serial key data and said control signals are produced in response to the serial input data and the clock pulses, or in response to the serial input data and other pulses that are generated in response to the clock pulses;
- either a dial pulse generating circuit or a dual tone multi frequency signal generating circuit;
- a selection circuit which receives the clock pulses from said clock generating circuit, the key input signal or a signal corresponding the key input signal, the serial input data, and the parallel output signals from said processor;
- outputs, in parallel with each other, the parallel signals from said processor during normal operation;
- and outputs, in parallel with each other, the clock pulses from said clock generating circuit, the key input signal or the signal corresponding to the key input signal, and the serial input data during a power source interruption;
- a data converting and producing circuit which produces dial data from the output signals received from said selection circuit;
- a main substrate provided with said processor, either said dial pulse generating circuit or said dual tone multi frequency signal generating circuit, said selection circuit, and said data converting and producing circuit;
- wiring through which the clock pulses, the key input signal, and the serial input data are inputted in parallel with each other to both said selection circuit and said processor;
- and
- a power source circuit which supplies electric power from a telephone line to either said dial pulse generating circuit or said dual tone multi frequency signal generating circuit, said clock generating circuit, and said data converting and producing circuit on said main substrate and the panel substrate.