| 摘要 |
PURPOSE: A smart card capable of maintaining a security between multi-application programs is provided to maintain a security of a code and data between multi-application programs stored in a smart card by preventing a code and data which are used one application from being accessed by other application. CONSTITUTION: An integrated circuit includes a CPU(10), a memory protection unit(20), and a memory(30). The memory(30) constituted by one out of a ROM, an EEPROM, and a RAM. Otherwise, a ROM, an EEPROM, and a RAM are constituted in the memory(30) individually as different uses. A program code and data are stored in the memory(30). The memory protection unit(20) includes registers(21,22) for storing an upper limit address and a low limit address for restricting a reading of data from the memory(30) by an application program. Also, the memory protection unit(20) includes registers(23,24) for storing an upper limit address and a low limit address for restricting a writing of data from the memory(30). In a normal mode, the CPU(10) accesses to the remaining area besides an area between a reading restriction upper limit address and a reading restriction low limit address of the memory(30) stored in the registers(21,22) and an area between a writing restriction upper limit address and a writing restriction low limit address of the memory(30) stored in the registers(23,24). In a privilege mode, the CPU(10) accesses to all areas of the memory(30).
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