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Wear leveling techniques for flash EEPROM systems

  • US 6,594,183 B1
  • Filed: 06/30/1998
  • Issued: 07/15/2003
  • Est. Priority Date: 09/13/1991
  • Status: Expired due to Fees
First Claim
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1. A storage device employing a flash memory, wherein a storage area of said storage device is divided into a plurality of physical sectors identified by physical addresses, said storage device includes:

  • logical address conversion means which receives a logical address of data in a data writing operation and converts said logical address into a physical address, a memory controller for receiving said physical address resulting from the conversion by the conversion means, and writing said data into a respective physical sector;

    wherein said logical address conversion means converts a logical address received in the writing operation to the physical address which is different from the physical address to which said logical address conversion means converted a logical address, identical to the logical address to be presently converted, in a preceding writing operation, erase operations reference means for storing a number of erase operations of respective erasing sector groups each of which comprises one or more physical sectors erased together in one erasing operation when erasing data stored in the physical sector included in the erasing sector groups, and erasing control means for erasing the erasing sector groups in the erasing operations, referring to said erase operations reference means, in which the number of erasing operations performed by the erasing sector groups are averaged.

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