Nonvolatile semiconductor memory device having means for selective transfer of memory block contents and for chaining together unused memory blocks
DCFirst Claim
1. A nonvolatile semiconductor memory device using an EEPROM, comprising:
- memory means having a memory cell array divided into a plurality of blocks;
managing means for managing unused blocks of said plurality of blocks in which new data is to be written, said unused blocks including erased blocks, which are physically erased, and non-erased blocks, which are logically erased but are not physically erased;
erasing means for discriminating said erased blocks of said unused blocks from said non-erased blocks of said unused blocks and erasing data stored in said non-erased blocks; and
control means for writing data into at least one block of said erased blocks of said unused blocks managed by said managing means, whereinin case that said data written by said control means is generated by changing data recorded in a different block of said memory means when said data recorded in said different block is not necessary, said control means informs said managing means that said different block is a non-erased block, and when said data recorded in said different block is necessary, said control means copies said data recorded in said different block to one of said erased blocks in which new data is to be written.
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Abstract
A nonvolatile semiconductor memory device using a NAND-type EEPROM includes a memory unit, a management unit, an erasure unit, and a control unit. The memory unit has a memory cell array divided into blocks each constituting a minimum quantity of data that may be erased. The management unit manages unused blocks. The erasure unit discriminates erased blocks of the unused blocks from non-erased blocks of the unused blocks to erase data stored in the non-erased blocks. The control unit writes data into at least one block of the unused blocks managed by the management unit. In the control unit, when a content of the written data is obtained by changing data recorded in a different block of the memory unit, and the data recorded on the another block is not necessary, the management unit receives information that the different block is an unused block. When the data recorded in the different block is necessary, a necessary part of the data recorded in the different block is copied to a block in which new data is to be written.
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Citations
21 Claims
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1. A nonvolatile semiconductor memory device using an EEPROM, comprising:
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memory means having a memory cell array divided into a plurality of blocks; managing means for managing unused blocks of said plurality of blocks in which new data is to be written, said unused blocks including erased blocks, which are physically erased, and non-erased blocks, which are logically erased but are not physically erased; erasing means for discriminating said erased blocks of said unused blocks from said non-erased blocks of said unused blocks and erasing data stored in said non-erased blocks; and control means for writing data into at least one block of said erased blocks of said unused blocks managed by said managing means, wherein in case that said data written by said control means is generated by changing data recorded in a different block of said memory means when said data recorded in said different block is not necessary, said control means informs said managing means that said different block is a non-erased block, and when said data recorded in said different block is necessary, said control means copies said data recorded in said different block to one of said erased blocks in which new data is to be written. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A memory system including a nonvolatile semiconductor memory device, comprising:
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memory means having an array of memory cells divided into a plurality of blocks including unused blocks, said unused blocks comprising erased blocks, which are physically erased, and non-erased blocks, which are logically erased but are not physically erased; erasing means for discriminating said erased blocks of said unused blocks from said non-erased blocks of said unused blocks and erasing data stored in said non-erased blocks; and control means for writing data to said unused blocks on the basis of an order in which said unused blocks are arranged. - View Dependent Claims (17, 18, 19, 20, 21)
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Specification