(1) Field of the Invention
The present invention relates to a portable card medium suitable for use in an IC (Integrated Circuit) card which can realize a plurality of application functions, and to a method for managing a memory space of the portable card medium, a method for issuing the portable card medium, and a method for writing program data on the portable card medium. Further, the invention relates to a computer readable recording medium with a memory space management program recorded therein.
(2) Description of the Related Art
An IC card is a portable card medium including a built-in IC (Integrated Circuit) which can contain a larger amount of data than that of data in a conventional magnetic recording card, and is personally held for use in recording of personal information, and so forth. Thus, by connecting the IC card to a host apparatus, it is possible to realize application processing as an extension of processing in the magnetic recording card.
That is, as described above, in the IC card, it is possible to provide a greater storage capacity than that of the magnetic recording card, and enhance a security function of recorded personal information (the security function of protecting the personal information, and so forth).
Here, as shown in FIG. 23, an IC card 100 includes a CPU (Central Processing Unit) 101, a connect portion 102 having the function of interfacing with the outside of the card, and a memory 103 for data storage. For example, an erasable programmable read-only memory (EPROM) is used as the memory 103.
The CPU 101 includes a ROM (Read Only Memory) 101a containing a program for driving the CPU 101, a RAM (Random Access Memory) 101b containing data used for program execution, a control portion 101c to make a control such as various command processing according to the program recorded in the ROM 101a, and an operation part 101d to perform an operation on data.
In recent years, by using the IC card, active development has progressed on a system in which an electronic money is used instead of cash. Since various quarters have tried experiments on such an electronic money system, quick progression of the system has been made toward a practical stage.
Here, in the electronic money system, electronic money information equivalent to cash (information about an amount of money in user's hand) is transferred to the IC card held by a user through, for example, an automated teller machine (ATM) of a bank. When the user makes a payment by the money information, the information of paid money is transferred to a creditor. The system allows various types of commercial transactions to be made without delivery and receipt of cash and adoption of credit management.
Meanwhile, a commonly used type is the IC card 100 including only a single application function for the electronic money as described above. However, as the memory has a greater capacity and the CPU (Central Processing Unit) has a higher processing speed in the integrated circuit of the IC card in recent years, a study has been conducted of an IC card having a plurality of application functions.
Here, in the IC card in which only the single application function is available, a program for realizing the application function is previously written on hardware, i.e., the ROM 101a of the IC card 100.
On the other hand, the IC card may have the plurality of application functions (multi-application function) as described above. In this case, there is one method in which the user can load a program for realizing the application function such that the user can optionally select an application.
That is, before using the IC card, the user can individually write (load) the program for realizing the desired application function on the IC card, thereafter using the card as a multi-function IC card.
However, when the IC card is used as a portable card medium capable of realizing the plurality of application functions as stated above, the single memory 103 contains data to be processed and managed by the respective programs. Hence, data to be managed by one program may be accessible to and fetched by another program. In such a case, there is a problem in that it is difficult to provide sufficient security of the stored data.