JP3130588B2 - Storage media - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage medium such as an IC card, and more particularly to a data storage system for storing data in a data memory in word units.

[0002]

2. Description of the Related Art In recent years, as a new portable data storage medium, an IC card incorporating a nonvolatile data memory and an IC chip having a control element such as a CPU for controlling the same has been developed.

In this type of IC card, a built-in control element accesses a built-in data memory, and inputs and outputs necessary data in response to a request from an external device. The data memory is divided into a plurality of areas, and selectively accesses the target area.

Conventionally, in such an IC card, a method of storing data in a data memory is to divide one unit of data to be stored into a plurality of data based on the concept of a word and write each of the divided data in word units. It is a thing.

This word usually includes a BCC (Block Check Character) field,
When writing the divided data in a word, the BCC of the data is calculated, and the data and the BCC are simultaneously written in the field. When reading data, the validity of the corresponding data is confirmed by a BCC check.

[0006]

However, in the conventional data storage system, variable-length data is stored in a word. However, in the calculation of the BCC, the data and the remaining space in the word are invalidated. This was done including data. In this case, even if only the invalid data in the remaining word space changes, a read target data error occurs, and the reliability cannot be ensured. Therefore, an object of the present invention is to provide a storage medium that can ensure high reliability as a system.

[0007]

According to the present invention, a storage medium stores data in word units and outputs data stored in the storage means to the outside based on a command input from an external device. A storage medium having an input / output unit, a division unit that divides data input from the external device through the input / output unit into a plurality of words, and First creation means for creating check data for validity check, each data divided in the storage means, each check data created by the first creation means, divided into word units, Writing means for writing the chain information of each data in correspondence with each other, and adding invalid data to divided data less than a word unit and writing the data; and When a data read command is input via the input unit, the data in the word and the corresponding check data are read in order from the word corresponding to the leading end of the chain of the storage unit based on the chain information stored in the storage unit. Reading means for outputting data, extracting means for extracting data other than the invalid data added by the dividing means from the data read by the reading means, and checking for validity confirmation of the data extracted by the extracting means. Second creating means for creating data, checking means for confirming the validity of the data based on the check data created by the second creating means and the check data read by the reading means, Means for temporarily storing data whose validity has been confirmed by the reading means, which is sequentially read by the reading means and created by the second creating means. Temporary storage means for storing data that has been validated by the received check data so as to be added to the already stored data; and inputting when all the data in a chain relationship is stored in the temporary storage means. Control means for controlling output to the external device via output means.

[0008]

Since check data (for example, BCC) for validity confirmation is created only for the actually input and divided data, when storing variable-length data in a fixed word, invalid data in the word is lost. Even if it changes, necessary data is regarded as normal, so that high reliability of the system can be secured.

[0009]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 9 shows a configuration example of a card handling device to which the IC card according to the present embodiment is applied, for example, used as a terminal device of a financial system or a shopping system. That is, this device
The C card 1 can be connected to a control unit 3 including a CPU or the like via a card reader / writer 2, and a keyboard 4, a CRT display device 5, a printer 6, and a floppy disk device 7 are connected to the control unit 3. Be composed.

FIG. 8 shows an example of the configuration of the IC card 1, in which a control element (for example, CPU) 11 as a control unit,
It is composed of a non-volatile data memory 12, a program memory 13, and a contact section 14 for obtaining electrical contact with the card reader / writer 2; Element 1
1, the data memory 12, and the program memory 13) are configured by one (or a plurality) of IC chips and are embedded in the IC card body.

The data memory 12 is used for storing various data, and is composed of, for example, an EEPROM. The program memory 13 stores, for example, a mask R
It is composed of an OM and stores a control program of the control element 11 and the like.

The data memory 12 is divided into a plurality of areas as shown in FIG. 5, for example, and each area is given an area number [00, 01,...]. Of these, area [00] has area [01,0]
2,...], The number of words dividing the area, and the number of bytes of the word are stored in correspondence with the area number.

For example, the head address of area [01] is aaa, and the number of words dividing the area is Wa.
The number of bytes of each word corresponds to Sa bytes. And each area [01, 02, ...]
It is divided by words having a certain fixed length (S bytes), and a word number is assigned to each of these words.
The word number is “1” for the word located at the head of the area, and thereafter, the word number is sequentially increased by one.
Indicated by data.

FIG. 6 shows a state in which data is stored in a certain area, and chain information, identification information, and a BCC field are added to each divided data. As the chain information, the word number of the word in which the succeeding data is stored (that is, the storage position information of the subsequent divided data) is used.

The identification information specifies whether or not the data is the leading data of the chain. For example, as shown in FIG. 7, the identification information is composed of one byte (8 bits), and the most significant bit (MSB) is set in the byte. Others are dummy. That is, if the MSB is “0”, it indicates the leading data, and if the MSB is “1”, it indicates other data. BC
In the C field, a BCC calculated as described later is written as check data for validity confirmation. In addition,
The total data length (the total number of bytes) including the subsequent divided data is added to the leading data of the chain.

Next, in such a configuration, the data storage method of this embodiment will be described in detail. When writing data to the data memory 12, write command data having a format as shown in FIG. 3 is input from the card reader / writer 2 to the IC card 1. In IC card 1,
The control element 11 recognizes the write function code included in the write command data and executes a write process based on the flowchart shown in FIG.

That is, first, the total number of bytes of the write data is recognized based on the data length included in the input write command data, and then it is determined whether or not all the data can be stored in the access target area (S1). If not, response data indicating a byte number error is output (S2).
The process ends.

If the data can be stored (S1), the write data included in the input write command data is divided for each byte number of words (S3). Further, for each divided data, for example, EX of all bytes constituting the divided data is obtained. A BCC as check data, such as a result of -OR (excessive OR), is calculated (S4).

Next, each of the divided data is sequentially written in the access target area of the data memory 12 in word units, and the B calculated in the corresponding BCC field is calculated.
Write CC. At this time, the word number of the written word is temporarily stored in the RAM in the control element 11 (S5).

When it is recognized that all of the divided data have been written normally (S6, S7), the word numbers stored in the RAM are added as chain information in order from the last written word. . In this case, the chain information of the last written word is set to "0" (S9), indicating that it is the data at the end of the chain, and the next chain information and thereafter are R
The word numbers are assigned to the AM in order from the last held word number (S10). If the data could not be written normally in step S6, response data indicating a write error is output (S8), and the process ends.

When all the chain information has been added (S1
1) The MSB of the identification information of the word to which the chain information is finally assigned is set to "0" (S12), indicating that the data is at the leading end of the chain, and outputting response data indicating a normal end. (S13), the process ends.

Here, a specific description will be given with reference to FIG. 6. For example, the write data is represented by W11, W12, W13.
And sequentially write in each word of the word number “1, 2, 3” in that order. Further, the divided data W11, W
BCC is calculated for each of the WCCs 12 and W13, and the BCC calculated in the corresponding BCC field, ie, BCCw1
1, BCCw12 and BCCw13 are written. , Then R
The word numbers “1, 2, 3” are stored in the AM in that order.

Next, "0" is added to the chain information portion of the data W13, "3" is added to the chain information portion of the data W12, and "2" is added to the chain information portion of the data W11. Then, the MSB of the identification information of the data W11 to which the chain information is added last is set to “0”.

Next, when reading data from the data memory 12, read command data having a format as shown in FIG.
To enter. In the IC card 1, the control element 11 recognizes the read function code included in the read command data and executes a read process based on the flowchart shown in FIG.

That is, first, by referring to the identification information section in the access target area, the one whose MSB is "0" is found (S21). If not found, response data indicating that data has not been written is output (S22), and the process ends.

If found (S21), counting from the beginning,
It is checked whether or not there is a word which is "0" or more than the read target data number included in the input read command data (S23, S24). If it does not exist (S24), response data indicating that there is no data number to be read is output (S25), and the process ends.

If there is (S24), the word whose MSB of the identification information corresponding to the data number to be read is "0" is referred to, the data in the word and the corresponding BCC are read, and the read data is read. Is temporarily stored in the RAM (S26). Then, a BCC check is performed (S
27) If the validity of the corresponding data cannot be confirmed,
Outputs response data indicating a read data error (S
28), end the processing.

If the validity of the corresponding data can be confirmed (S27), the word having the following data is recognized by the corresponding chain information, and the data in the word and the corresponding BCC are read out (S29, S30, S31), A BCC check is performed in the same manner as above (S32), and if the validity can be confirmed, the read data is added after the data previously stored in the RAM (S33). This behavior is
The word data whose chain information is "0" is stored in RAM
(S29), the data held in the RAM is output (S34), and the process ends.

As described above, since the BCC is created only for the actually input and divided data, for example,
Even if invalid data (invalid data in a word) indicated by hatching in FIG. 6 changes, necessary data can be recognized as normal. Therefore, high reliability as a system can be secured.

In the above-described embodiment, the case where data is stored in units of words in the data memory built in the IC card has been described. However, the present invention is not limited to this. Can be similarly applied to the case where data is stored in word units.

[0032]

As described above, according to the present invention, when variable-length data is stored in a fixed word, necessary data is regarded as normal even if invalid data in the word changes. A storage medium that can ensure high reliability as a system can be provided.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a data writing process.

FIG. 2 is a flowchart illustrating a data reading process.

FIG. 3 is a diagram showing a format example of write command data.

FIG. 4 is a diagram showing a format example of read command data.

FIG. 5 is a diagram showing a configuration of a data memory.

FIG. 6 is a diagram showing an example of a state where data is stored in an area.

FIG. 7 is a diagram showing a configuration example of identification information.

FIG. 8 is a block diagram schematically showing the configuration of an IC card.

FIG. 9 is a block diagram showing a configuration of a card handling device.

[Explanation of symbols]

1 ... IC card, 2 ... Card reader / writer, 11
... Control element (control unit), 12 data memory (storage medium), 13 program memory.

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G06F 12/16 G06K 19/00-19/07 G06F 11/10 G11C 29/00

Claims (1)

(57) [Claims] 1. A storage medium comprising: storage means for storing data in word units; and input / output means for outputting data stored in the storage means to the outside based on a command input from an external device. Dividing means for dividing data input from an external device via the input / output means into a plurality of words, and generating check data for validity confirmation for each of the data divided by the dividing means. 1, the divided data in the storage unit, the check data created by the first creating unit, and the chain information of the data divided in word units. A writing unit for adding and writing invalid data to the divided data which is less than the writing or word unit; and a data read command from the external device via the input / output unit. Read means for sequentially reading data in the word and corresponding check data from a word corresponding to the leading end of the chain of the storage means based on the chain information stored in the storage means, Extracting means for extracting data other than the invalid data added by the dividing means from the read data; and second generating means for generating check data for validity confirmation on the data extracted by the extracting means. Checking means for checking the validity of the data based on the check data created by the second creating means and the check data read by the reading means; and data verified by the checking means. Are temporarily read out by the reading means, and correct by the check data created by the second creating means. Temporary storage means for storing the data confirmed to have the property to be added to the already stored data; and when all the data in a chain relationship are stored in the temporary storage means, A storage medium, comprising: control means for controlling output to an external device.