Data card circuits
First Claim
1. A data card of the type comprising an integrated circuit on a semiconductor chip embedded in a plastic card, the circuit including a non-volatile memory having a transport code preprogrmamed therein, control circuitry for controlling the circuit, a comparator having a first input coupled to an input node of the circuit for receiving an externally-applied code and a second input coupled to said memory for comparing said externally-applied and transport codes, and a first irreversible switch coupled to an output of the comparator such that said first irreversible switch is actuated if the externally-applied and transport codes match.
4 Assignments
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Accused Products
Abstract
An integrated circuit for a data or "smart" card includes a non-volatile memory (8) having a transport code preprogrammed therein, control circuitry (10), a comparator (24) for comprising an externally-applied code and the transport code, and a fuse (26) which is blown if the two codes match thereby allowing the card to be initialised with a personal identification number and initial credit values. A second fuse (28) may also be provided which is blown if the two codes do not match and sensing means (32, 34) sense the status of the two fuses (26, 28) and block any further attempts to initialise the card if the second fuse (28) is blown and the first fuse (26) is not.
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Citations
19 Claims
- 1. A data card of the type comprising an integrated circuit on a semiconductor chip embedded in a plastic card, the circuit including a non-volatile memory having a transport code preprogrmamed therein, control circuitry for controlling the circuit, a comparator having a first input coupled to an input node of the circuit for receiving an externally-applied code and a second input coupled to said memory for comparing said externally-applied and transport codes, and a first irreversible switch coupled to an output of the comparator such that said first irreversible switch is actuated if the externally-applied and transport codes match.
Specification