| 摘要 |
<p>A modem for connecting a computer (100) or the like to a line (LT) of a telephone network (PTN), the modem being of the type that includes a control logic circuit (210) and a modulator/demodulator circuit (220), a computer interface circuit (240), and a telephone line interface circuit (230). The modem has a telephone line interface circuit which comprises: a plurality of terminals (S1, S2, S7, S4, S5) for control signals; switching means (MUX, OC7, OC4, OC5) controlled by the control signals; and a plurality of components (R9-R12, C3; R1-R3, PTC1) connected to the switching means so as to cause the AC impedance and DC voltage/current characteristics of the circuit to vary as a function of the received control signals. An identification circuit (250) is also provided including means for reading information representative of the country in which the modem is being used, which information is contained in means (300) for connecting the modem to the telephone line. The control logic circuit (210) is suitable for applying control signals (S1, S2, S7, S4, S5) that are determined as a function of the information read to the telephone line interface circuit (230). The invention is particularly applicable to portable computers.</p> |
