Importance

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Abstract

A portable computer has a modem telephone line expansion system, and includes: modem circuitry coupled to the portable computer system; a line interface section for reducing a line voltage across a telephone line to a low voltage analog signal level; and a line switch provided between an output of the line interface section and an input of the modem circuitry, and an expansion port the line switch selecting one of the telephone lines leading from the output of the line interface and the expansion port to the line input of the modem circuitry in response to a control signal produced when the portable computer is coupled to a docking station. The line interface includes a transformer with its primary coil connected to the telephone line and of its secondary coil connected to selected terminals of the line switch. Further, an expansion system for use with the above-mentioned type portable computer has a telephone line input port for connecting to a telephone cable; and an extra line interface section provided near the telephone line input port for connecting the telephone line to a port to be coupled to the portable computer.

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First Claim