STORAGE DEVICE WITH REWRITABLE NONVOLATILE MEMORY, AND CONTROL METHOD OF NONVOLATILE MEMORY FOR STORAGE DEVICE

摘要

PROBLEM TO BE SOLVED: To efficiently and evenly average the writing frequency to each physical block in a rewritable nonvolatile memory.

SOLUTION: A CPU 11 adds 1 to the writing frequency to a corresponding entry of a writing frequency table 141 according to the writing to a physical block in a flash memory 12. A replacement flag is set on in the entry corresponding to a physical block replaced by a physical block the writing frequency of which reaches a check frequency. When the writing frequency reaches the check frequency as the result of addition of 1 to the writing frequency to the entry of the table 141, the CPU 11 searches a block with the least wiring frequency of blocks having no replaced flag in reference to the table 141. The CPU 11 replaces the block which reaches the check frequency by the searched block, and the replaced flag is set on in the entry corresponding to the searched block.

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