| 摘要 |
PROBLEM TO BE SOLVED: To simplify the management of data requiring frequent rewrite and to prevent a memory capacity from being reduced by such data. SOLUTION: A file #1 is written on an irreversible write memory 3 and file management information #1 for managing the file is written on a memory area 4. Then, new user data are written in an unused area on the memory 3 as the file #2. Together with that, the file management information #1 is sucked up into a controller 2, the file management information is updated by the processing of a host device and the file management information #2 after being updated is written in the memory area 4. The rewrite of the file management information is facilitated. Also, since the latest file management information is provided in the memory area 4 inside this memory unit 1, the file management information is easily managed and the memory capacity of the irreversible write memory 3 is prevented from being reduced by the file management information.
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