Compagnie Internationale Pour L'informatique Cii-honeywell Bull (societe

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Compagnie Internationale Pour L'informatique

Compagnie Internationale Pour L'informatique Cii-honeywell Bull

Georges M Giraud

Jean H Mollier

Each card of a set of credit cards includes a memory having plural memory fields. The memory of each card in a set includes a first unalterable multi-bit field indicative of an identification of an external means with which the card can be used, as well as a second unalterable mutli-bit field indicative of operations that can be performed with the card on the external means and an alterable multi-bit field indicative of the number of credit units available to a card holder. Each card includes circuits for controlling the memory, and means for temporarily coupling the memory and circuits to the external means. Each of the first and second unalterable bit fields includes n bits. A change from one bit state to the other bit state of a predetermined number, m, of bits in the unalterable fields of each card in the set is irreversible after imprinting, where m is equal to or less than n.

System for keeping account of predetermined homogeneous units

An arrangement for both exchanging data between first and second devices and supplying power from the first to the second device, all through only two interconnecting lines or contacts. Data transmission from the first to second device is accomplished by a modulated current generator in the first device connected to the two liens. Data transmission from the second to the first device is accomplished by a modulator which shunts the two lines while the current generator supplies a current, thus varying the voltage across the line in a manner which may be sensed by a comparator in the first device. In order to supply power to the second device, the second device includes a network having at least one unidirectional conduction member, such as a diode, connected to the two lines.

Arrangement for providing a power supply and transmitting electrical

A credit card system includes a credit card containing a memory for storing coded information indicative of: an identification of the use for which the article is intended, an identification of units used to keep account of operations which are performed in connection with the credit card, and the number of units available to a holder of the credit card. The memory is structured so that the two identification data zones have bits wherein a change from one binary value to another is irreversible, to prevent tampering of the identification of the card. The card also includes circuits for controlling the memory and contacts for temporarily coupling the card to an imprinting and/or operating means that are respectively coupled to the card at the time it is purchased and when it is being used to purchase goods or services. When the card is purchased, the number of units is imprinted onto the card in the third zone, and the number of these units is decremented as the card is being used.

A system for transmitting digital signals between a fixed transmitter and a portable receiver which are temporarily interconnected by physical contacts which employs a single pair of contacts and a bidirectional data transfer technique to enhance the integrity of the data transfer. The single pair of contacts minimizes the possibility of data loss or contamination due to problems associated with temporary interconnecting and support a time-shared data transfer from a transmitter, which provides both data and synchronizing signals via a duration modulation technique on a pair of bipolar generators to a comparison receiver. The receiver synchronously acknowledges reception and provides, in turn, data back to the transmitter via a digital modulation of a signal current generator. A basic embodiment teaches the use of the apparatus as a secure data transmission means in a credit card reader, while an expanded embodiment shows the organization of a digital memory interconnection and data transfer scheme using the apparatus discloses.

Arrangements for transmitting electrical signals between two devices

A system for keeping account of predetermined homogeneous units by means of an article such as a card, carrying information which may be the amount of a credit balance, and an external device for operating on the information. In general, the balance on the card is initially validated. Thereafter, the balance is irrevocably drawn upon as desired until a zero balance is reached. In order to avoid a single large expenditure to validate the card, and at the same time to minimize the possibility of fraud, a memory in the card has a plurality of zones which are individually validatable. A separate validating field in the memory has validating bits corresponding to individual memory zones. The validity field is accessible by the external device only, and is protected by a coded key embodied in the card. To make the system usable for recording other than whole numbers of units, one of the zones may have a plurality of sub-zones. One of the sub-zones may be allocated to multiples or sub-multiples of individual units.

System for keeping account of predetermined homogenous units

An arrangement for checking contact betweena transmitter circuit situated upstream and a receiver circuit situated downstream, the contact being made to enable electrical signals corresponding to 1 and 0 logic states produced by the transmitter circuit to be transmitted in series to an input of the receiver circuit, is characterized in that it is formed by a first circuit situated upstream of the contact at the output of the transmitter circuit and a second circuit which is situated downstream of the contact at the input to the receiver circuit, the first circuit being designed to produce, at a first output connected to the second circuit, and if the contact is satisfactory, a current in a predetermined direction or the opposite direction in the presence of a signal representing a 1 or 0 logic state emitted by the transmitter circuit, the second circuit being designed to generate, at an output connected to the input of the receiver circuit, a signal corresponding to the logic state generated by the transmitter circuit when a current in the corresponding direction is emitted by the first circuit, the first circuit emitting a signal at a second output when the said current is present, this signal thus indicating that the contact is satisfactory.

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Le Vesinet, France

Georges M Giraud