Memory device
First Claim
1. A memory device comprising:
- an erasable and writable nonvolatile memory; and
a control circuit, wherein said control circuit is enabled to perform replacement processing of memory areas at a prescribed timing, and wherein said replacement processing is accomplished by writing stored data in a first memory area in which rewriting is relatively infrequent into an unused second memory area, and making the second memory area into which the writing has been done a used area in place of said first memory area.
1 Assignment
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Accused Products
Abstract
A risk of data garbling due to cumulative impact of disturbances occurring in memory areas in which no rewrite occurs is to be prevented. A memory device has an erasable and writable nonvolatile memory and a control circuit, wherein the control circuit is enabled to perform processing at a prescribed timing to replace memory areas. The replacement processing is accomplished by writing stored data in a first memory area in which rewriting is relatively infrequent into an unused second memory area, and making the second memory area into which the writing has been done a used area in place of the first memory area. Since this replacement processing is intended to replace memory areas in which rewriting is infrequent with other memory areas as described above, it is possible to prevent the risk of data garbling due to the cumulative impact of disturbances occurring in memory areas in which no rewrite occurs.
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Citations
16 Claims
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1. A memory device comprising:
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an erasable and writable nonvolatile memory; and
a control circuit, wherein said control circuit is enabled to perform replacement processing of memory areas at a prescribed timing, and wherein said replacement processing is accomplished by writing stored data in a first memory area in which rewriting is relatively infrequent into an unused second memory area, and making the second memory area into which the writing has been done a used area in place of said first memory area. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A memory device comprising:
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an erasable and writable nonvolatile memory; and
a control circuit, wherein said control circuit is enabled to perform replacement processing of memory areas at a prescribed timing, and wherein said replacement processing is accomplished by replacing with a prescribed unused memory area a prescribed used memory area in which rewriting is less frequent than in the prescribed unused memory area.
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10. A memory device comprising:
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an erasable and writable nonvolatile memory; and
a control circuit, wherein said control circuit is enabled to perform replacement processing of memory areas at a prescribed timing, and wherein said replacement processing is accomplished by replacing a prescribed memory area with another in which rewriting is less frequent than that prescribed memory area and placing said other memory area in an unused state while said prescribed memory area after the replacement is being used.
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11. A memory device comprising:
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an erasable and writable nonvolatile memory; and
a control circuit, wherein said nonvolatile memory has an unused area distinguishing table for storing a distinguishing flag which indicates whether or not any memory area is an unused area, wherein said control circuit, in write processing, makes one of the unused memory areas indicated by said distinguishing flag the destination for data writing and is enabled to perform replacement processing at a prescribed timing on the used memory area indicated by said distinguishing flag, and wherein said replacement processing is accomplished by writing stored data in a first memory area in which rewriting is relatively infrequent into an unused second memory area, and making the second memory area into which the writing has been done a used area in place of said first memory area. - View Dependent Claims (12, 13, 14, 15, 16)
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Specification