Apple Inc.

Compagnie Generale De Constructions Telephoniques

Eric Gradeler

Steven J Young

Philippe A Le Bars

Robert E Cox

Rodger J Mohme

Barry Hochfield

Bernard Meunter

Circuitry is described for providing a telephone line interface circuit of a MODEM for a computer with an AC impedance and DC voltage/current characteristics required by a given type telephone network such that the telephone line interface circuit can be matchingly connected with the given type telephone network. The given type telephone network provides an identification code representative of the required AC impedance and DC voltage/current characteristics. The circuitry comprises a plurality of impedance components that, when connected to the telephone line interface circuit, determine the AC impedance and DC voltage/current characteristics of the telephone line interface circuit. A plurality of terminals are coupled to receive a plurality of control signals associated with the identification code. A switching logic is coupled (1) between the plurality of impedance components and the telephone line interfacing circuit and (2) to the plurality of terminals for selectively connecting the plurality of impedance components to the telephone line interface circuit under the control of the plurality of control signals so as to cause the telephone line interface circuit to have the required AC impedance and DC voltage/current characteristics. An identifying circuit is coupled to the given type telephone network for identifying the required AC impedance and DC voltage/current characteristics by receiving the identification code and converting the identification code into the plurality of control signals.

Modem having an improved line interface circuit, in particular for a

An additional line coupling circuit to an intercom telephone set having inserted between the additional line and the intercom telephone set, a d.c. line uncoupling circuit as well as means coupled to one of the wires of the line for transmitting signals on the line and means connected to one or the other line wires for receiving the signals transmitted on the line.

Additional line coupling circuit to an intercom telephone set

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Sceaux, France

Eric Gradeler