International Business Machines Corporation

Jean-Claude Froment

Michel Paul Verhaeghe

Gerard Orengo

Jean-Pierre Pantani

Jean-Louis H Marijon

A monolithic module acting as the interface between a modem and leased ('LL') or switched ('SL') telephone lines, mainly characterized in that: 1. It can be formed on a silicon chip (due to the absence of electromechanical relays or similar switching means), and 2. Its architecture is such that it makes it possible, by interconnecting or 'stacking' identical modules, not only to attach additional telephone lines, but also to increase the number of allowable modem configurations. The module (10, 10') comprises two controlled-type line amplifiers (DLL, DSL) which exhibit a high output impedance regardless of whether the power supplies are 'on' or 'off'; two controlled-type line receivers (RSL, RLL) which provide a very high input impedance whether the power supplies are 'on' or 'off'; and a wrap receiver (WRP) for testing the modem (to the exclusion of the telephone lines) and interconnecting or 'stacking' identical modules. The figure shows an embodiment wherein two of the modules are interconnected; various configurations can be obtained depending on the logic state of the control inputs (1 to 4 for module 10 and 1' to 4' for module 10') supplied by the modem.

Interface module for telephone lines

A digital signal distribution system for distributing digital signals to remote points of a machine. It is comprised of a distribution device arranged at each of said points. In each device, a receiver receives on its true and complementary inputs, the signal to be distributed. The drivers are connected to the receivers through a crossed connection, the true output of the receiver being connected to the complementary input of the driver, and the complementary output of the receiver being connected to the true input of the driver, so as to cancel the skew of the pulse width of the signal to be distributed. The signals on outputs of the driver circuits can be utilized locally or transmitted to another remote point.

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Villeneuve-Loubet, France

Jean-Claude Froment