JPH04152488A - Ic card - Google Patents

Abstract

PURPOSE:To execute the recovery of a directory pointer simply and in a short period of time even if a service interruption is generated by preparing two directory pointers, and selecting alternately two directory pointers, whenever a new directory is recorded. CONSTITUTION:Data A, B,... are recorded successively in a user area. In this case, an initial value of directory pointers DP1, DP2 is (y). In such a state, when first data A is recorded from an address (x), a directory A is generated, and only one of two DPs is updated. That is, only DP1 is updated to (a) from (y), and DP2 holds the value (y). Subsequently, when the data B is recorded from an address (z), this time, only DP2 is updated to (b), and DP1 holds its original value (a). In such a way, whenever a new directory is updated, DP1 and DP2 are selected alternately, and only one of them is updated. Accordingly, address information recorded in the end is held in one of them, and even if DP is lost at the time when a service interruption is generated, the recovery processing can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an IC card, and particularly to an IC card that records user data in file units and also records a file directory.

[Conventional technology]

In place of the currently popular magnetic cards, IC cards are expected to become more widespread in the future. Several types of common specifications have been established for this IC card so far.
It has already been put into practical use for limited applications.

- Boat fishing IC cards include CPU, ROM, RAM, EE
It is equipped with input/output terminals for connecting PRO, M, and these elements to external devices, and user data can be transferred to E.
It is recorded in file units in EPROM. Also, at this time, a directory for the recorded data file is created and recorded in the EEPROM. This directory is information indicating the address position and data length of data recorded in file units, and is essential information for reading data files. In this way, each time a new data file is recorded, a new directory is created and recorded. The directories that are created one after another in this way are sequentially and continuously recorded starting from a predetermined address position. Therefore, a directory pointer is provided to indicate the address position of the last recorded directory.

From the value of this directory pointer, it is possible to recognize up to which address position the directory is currently recorded. Normally, this directory pointer is also E
Each time a new directory is created and recorded, the value of this directory pointer is updated.

[Problem to be solved by the invention]

To access data on an IC card, insert the IC card into a reading/writing device, make electrical contact between the input/output terminals on the IC card side and the input/output terminals on the reading/writing device side, and then create a connection between the two. This is done by exchanging signals. Since the IC card itself does not have a built-in power supply,
Power for operating the IC card is also supplied from an external reading/writing device. Therefore, if an electrical contact failure occurs at the input/output terminals, a power outage occurs within the IC card. In general, IC cards are often carried by users in their pockets or handled carelessly, and it is difficult to completely suppress the occurrence of electrical contact failures at input/output terminals. It is fully predicted that an accident will occur where the card will be in a power outage state.

As described above, when a new data file is recorded in the IC card and a new directory is created and recorded, the directory pointer is updated. However, while this directory pointer is being updated (i.e. being rewritten)
If a power outage condition occurs, the correct contents of the directory pointer will be lost. In conventional IC cards, when such an accident occurs, the directory pointer is recovered by analyzing the contents of successively recorded directories one by one. However, such work is complicated and time consuming.

SUMMARY OF THE INVENTION An object of the present invention is to provide an IC card that can easily and quickly restore a directory pointer even if a power failure occurs inside the IC card.

[Means to solve the problem]

The present invention provides an IC card in which data in file units is recorded sequentially from a first address position in a storage area constituted by an EEPROM, and a directory for each recorded data is recorded sequentially from a second address position. , Prepare two directory pointers to indicate the address position of the last recorded directory, and each time a new directory is recorded, select the two directory pointers alternately, and select one of the selected directory pointers. Only the contents are updated to a value indicating the address position of the new directory.

[For production]

In the IC card according to the present invention, two directory pointers are prepared. Each time a new directory is created and recorded, one of the two directory pointers is selected alternately, and only the selected one is updated. In the end, one of the directory pointers indicates the address of the last recorded directory, and the other directory pointer indicates the address of the immediately preceding directory. Thus, even if a power outage condition occurs when updating a directory pointer and the contents of the directory pointer being updated are lost, the contents of the other directory pointer are retained. For this reason,
You can easily recover directory pointers in a short time.

[Example] The present invention will be described below based on an illustrative example. FIG. 1(a) is a block diagram showing a state in which an IC card is connected to a reading/writing device. IC card 10
There are three types of memory inside, namely ROMII, RA
M12. EEPROMI3 and CPU14 are built-in. ROM11 is a non-rewritable memory, and the CPU
It is used as a program area to hold programs for controlling the 14. The RAM 12 is a rewritable memory and is used as a work area for the CPU to operate. Further, EEPROMI3 is a memory that can be rewritten by applying a predetermined rewriting voltage,
Used as a user area for recording user data.

Since six signal lines are connected to the reading/writing device 20, six input/output terminals for connecting these signal lines are provided on the IC card 10. The purpose of each signal line is as follows.

(1) Signal line l10 Used to receive and pass data bidirectionally between the IC card 10 and the reading/writing device 20.

(2) Signal line R5T Used to give a heliset signal from the reading/writing device 20 side to the IC card 10 side.

(3) Signal line CLK Used to provide a clock signal from the reading/writing device 20 side to the IC card 10 side.

(4) Signal line VCC Used to supply vCC voltage from the reading/writing device 20 side to the IC card 10 side.

(5) Signal line GND Used to supply GND voltage from the reading/writing device W20 side to the IC card 10 side.

(6) Signal line vpp Not currently used.

FIG. 1(b) shows the EEPR shown in FIG. 1(a).
This is a memory map in OMI 3. In this example,
This EEPROMI3 has the address r o o o
~FFFFJ is assigned, and in the figure, the addresses increase along a column extending horizontally to the right from address r0000J in the upper left corner, and when the right end is reached, the next column at the bottom is similarly assigned from left to right. Address increases.

In this way, the final address is the address "F F
It is FFJ. This EEPROMI 3 is originally a memory used as a user area for recording user data, but in reality, as shown in the figure, system areas 1 and 2 are provided in addition to the user area. In these system areas 1 and 2, system information such as the user's ID code and PIN number are recorded, as well as areas for two directory pointers DPI and DP2 unique to the present invention (the area surrounded by the dashed line in the figure). ) is provided.

User data is recorded in the user area in file units, and the corresponding directory is also recorded in the user area. In this embodiment, data is sequentially recorded in file units in the forward direction (address increasing direction) from address X, and the corresponding directory is recorded in the reverse direction starting from address y (address decreasing direction). (Note that in FIG. 1(b), the address values of each part are indicated by lowercase alphabets surrounded by circles). For example, when recording the first data A, it is recorded in the forward direction from address X as shown in the figure, and the corresponding directory A is recorded in the reverse direction from address y. Subsequently, when recording the second data B, it is recorded in the forward direction from address 2 following data A, and the corresponding directory B is recorded in the reverse direction from address a following directory A. Generally, a directory pointer has a function of indicating address information regarding the last recorded directory.

In the above example, the value of the directory pointer will be updated sequentially to indicate y until directory A is recorded, then a after directory A is recorded, and b after directory B is recorded. .

FIG. 2 shows a general directory structure.

In this example, the directory is the area ID, area DIR
It is composed of three areas, one area BCC. In the area ID, a name for identifying this directory and information indicating the length of the entire directory are written. The area DIR is a part where information that is the main purpose of this directory is written, and a group of parameters such as the start address, data length, access right information, etc. of the corresponding data file are written. The last area BCC is an area for error checking, and contains area ID and area D.
This is an error check code calculated based on the data in the IR, and this check code is written in this area BCC. When reading the directory, this BC
Based on the check code written in C, it can be confirmed that there are no errors in the data. In this way, information essential for accessing each data file is written in each directory, and directory management is extremely important.

Now, as described above, each time a new directory is recorded, the directory pointer indicating the address value for the last directory is updated. That is,
In the example shown in FIG. 1(b), data A, B, C, D, E
are recorded in order, directories A, B, C, D, E
However, with conventional IC cards, there is only one directory pointer, so if a power outage occurs while updating the directory pointer, the directory pointer will be The contents will be completely lost. For example, in the example shown in Figure 1(b), if a power outage occurs while writing to directory E is completed and the contents of the directory pointer are being updated from d to e, the value of the directory pointer will be changed to is the new value e
A situation may occur in which neither the previous value d nor the previous value d remain. Of course, the previous values a, b,
There is no value left such as c. In such a case, in order to recover the contents of the directory pointer, it is necessary to trace the directories one by one starting from address y. In other words, the task is to analyze the contents of directory A starting from address y, find the start address a of the next directory B, then analyze the contents of directory B, and find the start address b of the next directory C. must be repeated.

In the IC card of the present invention, by providing two directory pointers, such recovery work can be easily performed in a short time. Hereinafter, the directory pointer update process according to the present invention will be explained using the diagram of FIG.

Now, let us consider a case where data A, B, C, D, and E are recorded in the order of data A, B, C, D, and E from a state where nothing is recorded in the user area shown in FIG. 1(b). In this case, the initial values of the directory pointers DPI and DP2 are both y. Here, when the first data A is recorded in the forward direction from address X, a corresponding directory A is created, and the data is recorded in the reverse direction from address y. As a result, the value of the directory pointer must be updated from y to a, but in the present invention, only one of the two directory pointers is updated. That is,
In the example shown in Figure 3, only the directory pointer DPI is updated from y to a, and DP2 remains at its original value y.
will remain retained. Subsequently, when the second data B is recorded in the forward direction from address 2, a directory B corresponding to this is created. Here, when referring to directory pointers DPI and DP2, one is at address a1.
The other one holds address y. Here, since address a is multiplied by address y, it can be determined that the younger address a is the address related to the last directory, and the newly created directory B is recorded in the reverse direction from address a. As a result, the value of the directory pointer must be updated to a new value, but this time only the directory pointer DP2 is updated to b. As shown in FIG. 3, the DPI still maintains its original value a.

In this way, each time a new directory is recorded, the DP
I and DP2 are selected alternately, and only the selected one is updated. That is, as shown in FIG. 3, when recording directory C, only the DPI is updated to address C,
When recording directory D, only DP2 is updated to address d, and when recording directory E, only DPI is updated to address e.

In this way, when two directory pointers are used and one is updated one by one, the address information regarding the last recorded directory is held in one of them (the younger of the two), Not only can it perform its original function as a directory pointer, but even if the directory pointer is lost during a power outage, the following recovery process can be performed. For example, consider a case in which a power outage occurs during the process of updating the contents of the directory pointer DPI to the address e after recording the directory E in the above example. In this case, even if the contents of the directory pointer DPI are completely lost, the contents of the other directory pointer DP
2, the information of address d still remains. Therefore, after the power is restored, it is only necessary to repeat the operation of recording the directory E again based on this address d, and perform the operation of updating the directory pointer DPI to the address e. As described above, in the IC card according to the present invention, the directory pointer recovery operation can be performed very easily and in a short time.

Although the present invention has been described above based on an illustrated embodiment, the present invention is not limited to this embodiment only.
In addition to this, it can be implemented in various other ways. For example, in the embodiment described above, the two directory pointers are provided in separate system areas, but they may be provided in the same area. Further, the directory shown in FIG. 2 is shown as an example, and the present invention is applicable to IC cards having directories of any other structure.

〔Effect of the invention〕

As described above, according to the IC card of the present invention, two directory pointers are prepared and updated alternately, so even if a power failure occurs inside the IC card, the directory pointer can be easily and quickly updated. You will be able to recover.

[Brief explanation of drawings]

Fig. 1(a) is a block diagram showing a state in which an IC card is connected to a reading/writing device, and Fig. 1(b) is a block diagram showing the state in which an IC card is connected to a reading/writing device.
Figure 2 is a diagram showing the memory map in the EEPROM shown in a), Figure 2 is a diagram showing the general directory structure,
FIG. 3 is a diagram illustrating the directory pointer update process according to the present invention. Patent applicant Dai Nippon Printing Co., Ltd. Applicant agent Patent attorney Hiroshi Shimura Figure 1

Claims (1)

[Claims] Data in file units is recorded in a storage area configured by an EEPROM in order from a first address position, and a directory for each recorded data is stored in a second address position.
In an IC card that records addresses sequentially starting from the address position, two directory pointers are prepared to indicate the address position of the last recorded directory, and each time a new directory is recorded, the two directory pointers are selected alternately. An IC card characterized in that only the content of one selected directory pointer is updated to a value indicating an address position regarding a new directory.