JP3088866B2 - IC card - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IC card,
The present invention relates to a writing method for an EEPROM in a card.

[0002]

2. Description of the Related Art As a new information recording medium replacing a magnetic card, an IC card is in the spotlight. This IC card can record a larger amount of information than a magnetic card, and has high security. At present, IC cards widely used include RAM, ROM, E
Three types of EPROM memories and a CPU for accessing the memories are built in. Usually this I
Since the C card itself does not have a built-in power supply, data to be stored is written into the EEPROM. I
Various information handled by the C card is stored in the EEPROM in the form of a data file, and each data file is composed of a plurality of records. Also, a file directory having information for accessing the data file is created, and this file directory is also stored in the EEPROM.

[0003]

The writing process to the EEPROM requires much longer time than the writing process to the RAM. That is, while the write time to the RAM is on the order of μs, the write time to the EEPROM is on the order of ms. For this reason, EEPRO
When writing to M, a process of transferring a set of data to be written to a write register and writing the set of data in the write register to the EEPROM is performed. In other words, writing to the EEPROM is performed for each write unit corresponding to the data length of the write register. However, in the conventional IC card, the data length of each record of the data file to be written in the EEPROM and the data length of the file directory are set irrespective of the writing unit, so that the efficiency of the writing process is low. There is. For example, in an IC card in which the writing unit is 32 bytes, when a record having a data length of 32 bytes is stored in the EEPROM, if the data can be written from the address corresponding to the head of the writing unit, the writing from the writing register to the EEPROM is performed. The writing process only needs to be performed once, but when writing from an address corresponding to the middle of the writing unit, the writing process needs to be performed twice. Such write processing is not only inefficient, but also involves rewrite processing for data belonging to another record that does not need to be rewritten (processing for rewriting the same data as before), so that the write durability of the EEPROM is reduced. There is also a problem of lowering.

Accordingly, an object of the present invention is to provide an IC card that enables efficient writing processing to an EEPROM and improves writing durability.

[0005]

Means for Solving the Problems (1) The first invention of the present application has at least three types of memories, RAM, ROM, and EEPROM, and a C having a function of accessing these memories.
And PU, the IC card with a built-in, the housing length of one record constituting the data file, n times of a write unit for EEPROM (n is a natural number) is set to the length of, this
Records whose actual data length is shorter than the storage length
Will write with this empty space added
Thus, one record is written to the EEPROM in units of the accommodation length regardless of the actual data length . (2) The second invention of the present application includes at least a RAM, a ROM,
In an IC card containing three types of memories of EEPROM and a CPU having a function of accessing this memory, the accommodation length of one file directory is determined by the EEPROM.
A file whose length is set to n times (n is a natural number) the writing unit for OM, and whose actual data length is shorter than this accommodation length
For directories, empty space is added for this short amount
And write to the EEPROM.
Write file directory to actual data length
Regardless, it is performed in units of storage length.

(2) The second invention of the present application provides at least RA
In an IC card including three types of memories, M, ROM, and EEPROM, and a CPU having a function of accessing the memory, the accommodation length of one file directory is set to be n times the writing unit for the EEPROM (n is (A natural number), and writing of one file directory to the EEPROM is performed in units of accommodation length.

[0007]

[Operation] According to the IC card of the present invention, the EEP
For a record of a data file or a file directory to be written to the ROM, an accommodation length corresponding to n times the unit of writing to the EEPROM is set. Therefore, when one record or one directory is stored, it must be consistent with the unit of writing. The written processing is performed. Therefore, efficient writing processing can be performed, and writing durability can be improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. FIG. 1 is a block diagram showing the general configuration of an IC card 10 currently generally used and a reader / writer 20 used for the IC card. The main components of the IC card 10 are a CPU 11, a ROM 12, a RAM 13, an EEPR
OM14. The CPU 11 communicates with the reader / writer 20 via an interface (not shown), and performs processing for accessing the memories 12, 13, and 14. When the IC card 10 is inserted into the housing of the reader / writer 20, the connection terminal on the IC card 10 side and the reader / writer 2
The connection terminal on the 0 side comes into contact, and both are electrically connected. That is, a G that defines a common ground potential is provided between the two.
An ND line, a VCC line for supplying power from the reader / writer to the IC card, a CLK line for supplying a clock, and an RST for supplying a reset signal
Lines and I / O lines for transmitting data in both directions are secured. Data transmission between the two is performed alternately one direction at a time through the I / O line.

[0009] The CPU 11 executes various processes based on programs prepared in the ROM 12. RAM1
Reference numeral 3 is used as a work area when the CPU 11 performs various processes. The EEPROM 14 is an electrically rewritable memory, and can store data even when the IC card 10 is disconnected from the reader / writer 20 and power is not supplied. Therefore, the data to be stored in the IC card 10 is stored in the EEP while connected to the reader / writer 20.
It is necessary to write it in the ROM 14.

FIG. 2 shows an IC generally used at present.
FIG. 3 is a block diagram illustrating a process of writing to an EEPROM in the card. For example, data transmitted from the reader / writer through the I / O line
It is assumed that a process of writing data in the ROM 14 is performed. In this case, the transmitted data is temporarily stored in the RAM 13 and then transmitted from the RAM 13 to the EEPROM 1.
4 is transferred. At this time, the data stored in the RAM 13 is transferred to the write register 15, and is written from the write register 15 to a predetermined address in the EEPROM 14. This is, as mentioned above, the E
This is because the time required for writing data to the EPROM 14 is on the order of ms, and is much longer than the machine cycle of the CPU 11. Therefore, this write register 1
5 is called a write unit, the RAM 1
The data in 3 is transferred to the EEPROM 14 for each writing unit. For example, assuming that the data length of the write register 15 is 32 bytes, 32 bytes are a unit of writing, and the data in the RAM 13 is stored in the EEPROM 14 as a group of data (data indicated by hatching in FIG. 2) every 32 bytes. Will be transferred.

Now, a memory map of the EEPROM 14 will be described so that a 32-byte writing unit corresponds to one row as shown in FIG. One row in this memory map is called one page. That is,
One page corresponds to a data area of 32 bytes. Then, a case is considered where a data file composed of three records, record and, is written in the EEPROM 14. In conventional IC cards, this 3
Since one record is written together, writing is performed as shown in FIG. Since the data length of each record differs, the address where each record is written becomes irregular. Such a conventional writing method is very efficient from the viewpoint of memory capacity. That is, since each record is filled and written without gaps, there is no useless memory area. However, there is an inefficiency in terms of the writing process.
There is also a problem in writing durability. For example, consider a rewrite process for updating the contents of a record. As aforementioned,
The writing process to the EEPROM 14 can be performed only in units of 32 bytes. In other words, it can only be done on a page-by-page basis. Therefore, when rewriting a record, it is necessary to perform a rewriting process for three pages of pages 2, 3, and 4. For this reason, assuming that 20 ms is required for writing in one writing unit, a total of 60 ms is required. Further, let us consider a case where the rewriting process for a record is performed 10,000 times while the EEPROM 14 has write durability capable of rewriting 10,000 times. In this case, there is no problem about the record reaching the limit of write durability. However, the rewriting process on a record results in rewriting 10,000 times for pages 2, 3, and 4. Therefore, even records and records that have not been subjected to the rewriting process are limited to the write durability limit. Will be reached.

In the IC card of the present invention, such a problem is solved by performing the following writing. That is, the storage length of one record constituting the data file is set to n times (n is a natural number) the writing unit to the EEPROM 14, and the writing of one record to the EEPROM 14 is performed in this storage length unit. It was done. A specific example is shown in FIG. In this example, n is defined as 2, and the accommodation length of one record is set to twice the length (64 bytes) of the writing unit. In other words, EEP
That is, two pages of the ROM 14 are allocated as a length for accommodating one record. As a result, two pages of memory area are secured for each record. That is, pages 1 and 2 are reserved for records, pages 3 and 4 are reserved for records, and pages 5 and 6 are reserved for records. When the records are written in such an allocation, for a record whose actual data length is shorter than the set accommodation length, an empty area (indicated by “*” in the figure) is generated in the memory for the shorter amount. As a result, the efficiency is reduced from the viewpoint of the memory capacity. However, no matter which record is updated, rewriting for two pages is sufficient, and writing for one writing unit takes 20 ms.
Assuming that time is required, only 40 ms is required. In this way, it becomes efficient from the viewpoint of the writing process. In addition, the problem of writing durability is solved. For example, even if a record is rewritten 10,000 times, the write durability of the record is not affected at all. The degree of integration of memory elements such as EEPROMs tends to be more and more increased, and inefficiency from the viewpoint of memory capacity will not become a very important problem in the future. It is considered that the efficiency is required. In this sense, the present invention will produce sufficient utility value in the future.

In the above-described embodiment, the present invention is applied to the writing of one record constituting a data file. However, the present invention relates to a file used for indicating a head address, a length, an attribute, and the like of a data file. It is also applicable for directories. That is, the accommodation length is also set for the file directory, and when writing one file directory to the EEPROM, the writing may be performed for each set accommodation length. Particularly, the file directory tends to be frequently rewritten, and it is of great significance to improve the write durability. Figure 3 shows the file directory.
When the data is stored by the conventional method as shown in (1), when the data is garbled in a few bytes in the middle, the directory stored at the subsequent address cannot be accessed, and the directory information is lost. There is a risk that it will. On the other hand, when data is stored by the method of the present invention as shown in FIG. 4, even if data is garbled in one directory, access to other directories is not affected. There is no risk of loss.

[0014]

As described above, according to the IC card of the present invention, the record of the data file or the file directory to be written in the EEPROM is:
When the storage length corresponding to n times the writing unit for the EEPROM is set and one record or one directory is stored, the writing process is always performed for each storage length, so that efficient writing process is possible. And the writing durability is also improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a general IC card and a reader / writer.

FIG. 2 is a block diagram showing a general writing process for an EEPROM.

FIG. 3 is a memory map showing a manner of writing data to a conventional general EEPROM.

FIG. 4 is a memory map showing an aspect of writing data to an EEPROM according to the present invention.

[Explanation of symbols]

 1 to 7: pages in the EEPROM 10: IC card 11: CPU 12, ROM 13, RAM 14, EEPROM 15, write register 20, reader / writer, and records constituting a data file

Continuation of the front page (56) References JP-A-2-46888 (JP, A) JP-A-4-313882 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G06F 3 / 08 G06F 12/04 510 G06K 19/07

Claims (2)

(57) [Claims] 1. At least RAM, ROM, EEPROM
In an IC card having three types of memory M and a CPU having a function of accessing this memory, the storage length of one record constituting a data file is defined as EEP.
A record whose length is set to n times (n is a natural number) the writing unit for the ROM and whose actual data length is shorter than the accommodation length.
For empty space, the empty area is added and written
An IC card, wherein one record is written to the EEPROM in units of the accommodation length regardless of the actual data length . 2. At least RAM, ROM, EEPROM
M, and a CPU having a function of accessing the memory.
The housing length for the file directory, n times of a write unit for EEPROM (n is a natural number) is set to the length of the
File directory whose actual data length is shorter than the storage length
For the memory, write an empty area by this short amount.
And writing the one file directory to the EEPROM in units of the accommodation length regardless of the actual data length.
card.