Method for operating a memory card

Details Method for operating a memory card Method for operating a memory card

1997-03-26

1999-06-29

Ho, Ruay Lian

Data processing: database and file management or data structures

Database design

Data structure types

G06F 1730

Patent

active

059182300

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention relates to a device for the permanent storage of formatted data.
Permanent storage of data is necessary in many areas of automatic data processing. They are, for example, sales in cash desks or diagnostic data in electronic devices. It is intended here to protect the stored data against erroneous erasure and intentional manipulation. A paper strip having the data printed on it has been used for this purpose to date.
It is desirable to use electronic memories instead of paper strips in order, in this way, to save space, to be able to further process the data automatically and to achieve a higher level of protection against falsification.
International Reference WO 87/07060 describes a memory card whose memory is subdivided by means of initialization into a number of data records of fixed length and which has a protection mechanism by means of different PINs.


SUMMARY OF THE INVENTION

The object of the invention is to specify such a memory, which can be employed flexibly.
The invention makes use of memory cards with processing power. In this case, the format of the data to be stored and the type of evaluation are established in an initialization phase. Afterwards, only data in this format can be stored.


DESCRIPTION OF THE PREFERRED EMBODIMENTS

The memory card used is a combination of an electronic memory with a processor and an input/output unit of the kind present, for example, in the SL44C40 memory card from Siemens. The input/output interface is in this case operated according to ISO Standard 7816. If a larger storage capacity is required, such a device can also be constructed from components on printed circuit boards and subsequently be encapsulated in order to preclude electrical manipulation of the memory contents. For the sake of simplicity, all of these variants are referred to as memory card in the following text.
In order to use such an arrangement as a memory device, a read-only memory in the memory card is equipped with a program. The data which is to be stored in the EEPROM, and the form in which it is to be stored in the EEPROM, is established beforehand. Also established are a transfer format and method at the interface. The program which satisfies these specifications is created and written to the read-only memory by means of a programming device. Afterwards, the memory card can be used for the intended purpose. If the format of the data to be stored changes, then a new read-only memory content is determined and programmed into new cards. The memory cards are provisioned separately for each application. If the content to be stored changes, for example, on account of legal prescriptions, then it is necessary to destroy memory cards which are not used up. Comprehensive provisioning is also necessary in the case of a multiplicity of different memory formats.
Therefore, a fixed program which is common to all the variants is used in accordance with the invention, which program determines the format and the form of the data to be stored by means of an initialization dialog.
The communication between the memory card and a device using it, for example a cash register, takes place via a communications protocol, predominantly according to ISO 7816. A simplified illustration is used below for the purpose of better comprehensibility. In this case, character sequences are transmitted. A format may be selected in which the first character contains the number of data characters, the second character is a type identifier for the data record and the following data characters depend on the type of data record. The format therefore:


______________________________________ Start Number Type Data Stop ______________________________________ AA n 1 = Init n characters of data 55 2 = Ident 3 = Data 4 = Read ______________________________________
For an Init data record, each data character defines a data field and is coded as follows:


______________________________________ Bit Meaning ______________________________________ 7 1 = Capable of summation 6 1 =

REFERENCES:
patent: 4935870 (1990-06-01), Burk, Jr. et al.
patent: 5546575 (1996-08-01), Potter et al.
patent: 5703795 (1997-12-01), Mankovitz
patent: 5778371 (1998-07-01), Fujihara
ISO/IEC 7816-4: 1993 (E), Information technology--Identification cards--Integrated circuit cards with contacts--Part 4: Inter-industry commands for interchange, pp. 1-41.

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