Method and apparatus for performing write operations in multi-level cell storage device
First Claim
1. A method for storing data in a memory comprising a plurality of cells capable of storing more than a single bit of data per cell, comprising the steps of:
- storing data in a first set of said memory cells in accordance with a write operation to said memory,, wherein each cell of said first set of said memory cells stores a single bit of said data; and
storing said data from said first set of said memory cells in a second set of said memory cells, wherein each cell of said second set of said memory cells stores more than one bit of said data.
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Abstract
A memory contains a plurality of memory cells that are capable of storing one or more bits of data in each memory cell. The memory stores, in response to a write operation, data corresponding to the write operation in a first set of the memory cells such that each cell of the first set of the memory cells stores a single bit. Thereafter, data from the first set of memory cells are transferred to a second set of the memory cells such that each cell of the second set of the memory cells stores more than a single bit of data. The write operation to the first set of cells is executed in a foreground operation, and in a subsequent background operation, data from the first set of memory cells are transferred to the second set of memory cells. The memory cells are non-volatile flash electrically erasable programmable read only memory (EEPROM) cells, and therefore require erasure before programming. Typically, memory cells are reclaimed in a background operation. However, if not enough memory cells are available for a write operation, then a set of memory cells are reclaimed in a foreground operation, and more than one bit of the data are stored in the reclaimed memory cells.
206 Citations
20 Claims
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1. A method for storing data in a memory comprising a plurality of cells capable of storing more than a single bit of data per cell, comprising the steps of:
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storing data in a first set of said memory cells in accordance with a write operation to said memory,, wherein each cell of said first set of said memory cells stores a single bit of said data; and storing said data from said first set of said memory cells in a second set of said memory cells, wherein each cell of said second set of said memory cells stores more than one bit of said data. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A circuit for storing data comprising:
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a plurality of memory cells capable of storing more than one bit per cell; and a write circuit, wherein the write circuit stores data in a first set of said memory cells in accordance with a write operation, wherein each cell of said first set of said memory cells stores one bit of said data, wherein the write circuit subsequently stores said data from said first set of said memory cells in a second set of said memory cells, wherein each cell of said second set of said memory cells stores more than one bit of said data. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A computer system, comprising:
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a central processing unit (CPU); memory coupled to said CPU; and a solid state disk drive coupled to said CPU, said solid state disk drive comprising; a plurality of memory cells capable of storing more than one bit per cell; and a write circuit, wherein the write circuit stores data in a first set of said memory cells in accordance with a write operation, wherein each cell of said first set of said memory cells stores one bit of said data, wherein the write circuit subsequently stores said data from said first set of said memory cells in a second set of said memory cells, wherein each cell of said second set of said memory cells stores more than one bit of said data. - View Dependent Claims (20)
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Specification