Apple Inc.

Barry Hochfield

Steven J Young

Philippe A Le Bars

Robert E Cox

Eric Gradeler

Rodger J Mohme

Nicolas Bocquet

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

A modem (200) for connecting a computer (100) or the like to a telephone network for data transmission purposes, the modem being of the type including a modulation/demodulation circuit for converting the digital signals of the computer into analog signals capable of being conveyed by the telephone network and vice versa, a computer interface circuit, and a telephone line interface circuit specially designed for a telephone network of a given type. The modem is characterized in that it comprises: a main circuit (210) designed to be placed inside the computer box (102) and incorporating the modulation/demodulation circuit (214) and the computer interface circuit (216); an auxiliary circuit (220) situated in a box (225) external to the computer box and incorporating the telephone line interface circuit; and disconnectable connection means (Cl, 230, 232) between the auxiliary circuit and the main circuit. The modem further includes means for at least periodically transferring an identification code from the auxiliary circuit to the main circuit, the identification code being stored in said auxiliary circuit and being representative of said given type of telephone network, means being provided in the main circuit for adapting the operating characteristics of said main circuit to said given type of network.

Reconfigurable modem for a computer or the like

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Noisy le Roi, France

Barry Hochfield