Memory system and control method thereof
First Claim
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1. A control method of a memory system including a nonvolatile memory having a plurality of blocks as data erase units, the method comprising:
- storing an erase time which indicates when data of each block is erased;
generating a block table indicating a correspondence relation between a status value indicating one of a free state and an in-use state and the erase time for each block;
selecting a first block which is set in a free state and whose erase time is oldest based on information of the block table; and
writing data supplied from at least an exterior into the first block.
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Abstract
A memory system includes a nonvolatile memory including a plurality of blocks as data erase units, a measuring unit which measures an erase time at which data of each block is erased, and a block controller which writes data supplied from at least an exterior into a first block which is set in a free state and whose erase time is oldest.
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Citations
23 Claims
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1. A control method of a memory system including a nonvolatile memory having a plurality of blocks as data erase units, the method comprising:
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storing an erase time which indicates when data of each block is erased; generating a block table indicating a correspondence relation between a status value indicating one of a free state and an in-use state and the erase time for each block; selecting a first block which is set in a free state and whose erase time is oldest based on information of the block table; and writing data supplied from at least an exterior into the first block. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A control method of a memory system including a nonvolatile memory having a plurality of blocks as data erase units, the method comprising:
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measuring an erase time at which data of each block is erased; counting an erase count of each block; generating a block table indicating a correspondence relation between a status value indicating one of a free state and an in-use state, the erase time and the erase count for each block; selecting a first block whose erase count is minimum among a preset number of blocks set in the free state starting from a block whose erase time is oldest based on information of the block table; and writing data supplied from at least an exterior into the first block. - View Dependent Claims (17, 18, 19, 20, 21)
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22. A control method of a memory system including a nonvolatile memory having a plurality of blocks as data erase units, the method comprising:
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measuring an erase time at which data of each block is erased; counting an erase count of each block; generating a block table indicating a correspondence relation between a status value indicating one of a free state and an in-use state, the erase time and the erase count for each block; selecting a first block whose erase count is minimum among a preset ratio of blocks set in the free state starting from a block whose erase time is oldest based on information of the block table; and writing data supplied from at least an exterior into the first block.
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23. A control method of a memory system including a nonvolatile memory having a plurality of blocks as data erase units, the method comprising:
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measuring an erase time at which data of each block is erased; counting an erase count of each block; generating a block table indicating a correspondence relation between a status value indicating one of a free state and an in-use state, the erase time and the erase count for each block; selecting a first block whose erase count is minimum among blocks which are set in the free state and whose erase times are older than a preset time based on information of the block table; and writing data supplied from at least an exterior into the first block.
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Specification