| 摘要 |
PURPOSE:To apply a single memory device to the plural types of IC cards, therefore to reduce the costs of a memory device and the IC card, by inhibiting the rewriting operation of data for each storage in case the specific digit of the storage unit of a memory device incorporated to the IC card to store data is equal to the prescribed value. CONSTITUTION:A rewriting inhibition means reads the data on each storage to be rewritten in a data writing mode and checks whether the leading digit of the data is equal to 0 or 1. If the leading digit is equal to 0, it is decided that the rewriting action of each storage is inhibited to finish the operation. While said rewriting action is possible, therefore the new data is written for each storage in case said leading digit is equal to 1. Thus it is possible to form a uniform memory device an IC card and to inhibit or permit optionally the writing of the input data. Therefore just a single memory device can cope with various types of IC card, thereby reducing the costs of the memory device and the IC cards.
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