JPS61107487A - Ic card - Google Patents

Abstract

PURPOSE:To reduce the necessary time required for writing data by rewriting only the address of which to be written in a EEPROM is different from the one already written. CONSTITUTION:When data to be written in the EEPROM 2 and the number of the data n are sent to a MPU 1 according to a write command from an external equipment, the MPU 1 sets the address of the EEPROM 2 to which the data is written, and also sets the number of data n to be written in a data counter. The MPU 1 sets the address to which one datum among the data is written, and reads the contents of the address. It compares the data (new one) to be written with the data (old one) read from the address, and do not rewrite the data for that address if both are same, keeping the old data. If both are different, it erases the data of the address, and rewrites the new data.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an IC card incorporating an integrated circuit, and more specifically, the present invention relates to an IC card incorporating an integrated circuit. This relates to a built-in IC card.

[Technical background of the invention and its problems]

In recent years, a so-called 1C card in which an integrated circuit is built into the card has been developed, and is about to be put into practical use.

This IC card has a much superior information storage capacity compared to the magnetic cards that are currently widely used.
It is also attracting a lot of attention because it has features not found in magnetic cards, such as being significantly superior in terms of information confidentiality and being able to have information processing functions. are collecting. One form of such an IC card is a microcomputer (hereinafter referred to as MPU) inside the card.
and at least one electrically erasable F ROM (hereinafter referred to as EE)
An IC card incorporating a ROM (referred to as FROM) is known. This card 'ti MPU''? has an information processing section and also has an EEPRO as a memo 11-.
M'? Information can be written, read, and erased freely. Generally, in EEPH, OM, it takes about 10m5 to write one byte. It takes about 10m5 to erase one byte, so it takes about 20m5 to rewrite one byte. This has the disadvantage that it takes a considerable amount of time to write, erase, or rewrite data using multiple electric currents. In addition, the lifespan of EEP ROM after data rewriting is generally about 10,000 times, and due to deterioration due to rewriting, EEPROM
There are concerns about the reliability of the data stored.

[Purpose of the invention]

Therefore, an object of the present invention is to provide an IC card equipped with an MPU and at least one EEFROM, which
To provide an IC card capable of shortening the time required for rewriting data to an EPROM, and suppressing deterioration of the EEPROM due to repeated data rewriting.

1. [Summary of the invention] The present invention has been made to achieve the above object, and is
When writing data to a certain address in an EPROM, is there a means for reading out the data stored at that address, and is the data to be written and the read data identical? This 1C card is characterized by having a means for distinguishing between the two addresses, and a means for rewriting the data of the address only when the two are not the same.

[Embodiments of the invention]

The present invention will be explained in detail below based on embodiments of the drawings.

The IC card according to the present invention, as shown in FIG.
The card body (0 contains a microcomputer (MPU) called IC module M (11) and this MPU11
The print board on which the external memory 11 connected to the pass line (31) and an electrically erasable PROM' (EEPROM) + 21 are mounted is omitted.

In an IC card with such a configuration, an external device:.

Upon receiving commands and data from the device, MPU Ill
When writing the data to the EEPROM+21, the MPU11 executes the following process using the write program stored in its internal memory.

That is, as shown in Fig. 2, when data to be written to EEFROM (2) and the number n of the data are transferred from an external device to MPUfl in response to a write command, MPUm writes each data. EEPROM12
+ address is set, and the number n% of data to be written is set in the data counter.

MPU 1ll) i For one of the data to be written, set the address to which the data is to be written, and read the contents of that address.

Next, compare the data to be written (new data) with the data read from the address (old data), and if they are the same, the old data will be maintained as is without rewriting the data for that address. do.

On the other hand, if they are not the same, the data at that address (old data) is erased and the data to be written (new data) is written.

When such processing is completed, the address counter returns 1? in either case. If the value of the data counter is not 0, there is still data to be written, so for writing the next data, the address is set to the next address and the same process as described above is repeated. When the above-described processing is completed for all data, the data counter lin becomes 0, and the execution of the write program is ended. For example, this IC card? P
When applied to an OS system, the IC card's E
123,456 (123,456) as balance data in E P ROM
With the data Pal being written, next 50
I bought 0 yen and the balance data is 123,156 (pH 1)
In the conventional case, all six digits would be rewritten, but according to the present invention, only the address corresponding to the last digit (4→1) is actually rewritten; Addresses where numerical values are stored remain unchanged.

〔Effect of the invention〕

The present invention has the configuration described above, and has an EEP
By rewriting only the addresses where the data to be written to the ROM is not the same as the data that has already been written, and not rewriting when they are the same, it is possible to avoid processing such as data reading from the EEPROM and comparison calculations. Even if these are additionally required due to the configuration, the processing speed is much faster than the rewriting time of the EEPROM, so it is possible to substantially shorten the time required for data writing.

Furthermore, since the number of times data is erased and written can be reduced, deterioration in the repeated life of the EEF ROM can be suppressed, and the reliability of stored data can be improved.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is an explanatory diagram of an IC card according to the present invention, and FIG. 2 is a flowchart of a writing program. 5... Pass line, C... IC card body, M...
・IC module

Claims (1)

[Scope of Claims] 1) In an IC card incorporating a microcomputer and at least one electrically erasable PROM, when data is written to a certain address of the electrically erasable PROM, data already stored at the address is An IC card characterized by having means for reading data, means for determining whether the data to be written and the read data are identical, and means for rewriting the data at the address only when the two are not the same.