Datacarriers with separate storage of read and write-inhibited m

Details Datacarriers with separate storage of read and write-inhibited m Datacarriers with separate storage of read and write-inhibited m

1993-02-22

1995-11-14

Black, Thomas G.

Communications: electrical

Continuously variable indicating

With meter reading

34082554, 365195, 365228, G07C 100, G11C 1500

Patent

active

054670810

ABSTRACT:
Portable data carriers are known for different applications, for example as so-called smart cards for bank transactions or for access control or for combined applications. For the various applications different subdivisions of the write/read memory in the data carrier are required so that given zones cannot be read and other zones can only be read and not be written. This subdivision is customarily implemented during the manufacture of the card or the chip. In order to obtain a chip which can be flexibly adapted to various applications, in accordance with the invention the memory in the data carrier is subdivided into a number of blocks which are inhibited from reading or writing by read inhibit and write inhibit information stored in different locations in one or two blocks of the memory. The writing in non-inhibited blocks can additionally be made dependent on a previous transmission of a correct password, the password also being stored in one of the blocks in the memory of the data carrier. As a result, the password as well as the inhibit information can be treated as normal information and, if necessary, they can also be repeatedly overwritten. When the block storing the write inhibit information, and preferably also the password, is inhibited from overwriting, part of the memory of the data carrier becomes a read-only memory.

REFERENCES:
patent: 3971916 (1976-07-01), Moreno
patent: 4211919 (1980-07-01), Ugon
patent: 4734568 (1988-03-01), Watanabe
patent: 5014312 (1991-05-01), Lisimaque et al.
patent: 5111433 (1992-05-01), Miyamoto
patent: 5119336 (1992-06-01), Itoh
patent: 5206938 (1993-04-01), Fujioka
patent: 5285055 (1994-02-01), Oonakahara et al.
patent: 5293424 (1994-03-01), Holtey et al.

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