Abstract: System for providing verified information exchange between a read/write unit (2) and an electronic record carrier (4) which stores the information as digital data in a memory (38). The exchange of data is controlled by a microprocessor (6) in or coupled to the read/write unit, which monitors whether the data to be stored in the memory (38) is being accurately stored therein. The information carrier includes a tuned circuit (34, 36) which is connected to an input/output (39) of the memory through a switching transistor (32). When a logic "high" value is present at its base, the transistor short-circuits the tuned circuit and so it no longer resonates. The tuned circuit is inductively coupled to a detector (14) in the read/write unit, which thereby detects the resonant or non-resonant condition and provides a corresponding logic signal to the microprocessor which compares such logic signal with the logic value of the data then being recorded. Any discrepancy is thereby detected.

Abstract: A selector circuit is arranged between a telecommunication subscriber line and a telephone set and a facsimile device. The selector circuit includes a tone detector and a voice detector and circuitry for connecting the subscriber line to the telephone set or the facsimile device depending on the output of the voice detector alone or the outputs of both the voice and tone detectors. In a first state, known as telephone priority, the selector circuit responds to an incoming call by sending a return message as to whether facsimile transmission is desired. The tone and voice detectors are then activated, and if either a voice signal or a tone signal is detected, the selector circuit connects the subscriber line to the facsimile device. Otherwise, the subscriber line is connected to the telephone set. In a second state, known as facsimile priority, the selector circuit responds to an incoming call by sending a return message as to whether telephone communications are desired.