| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a memory system having a NAND flash memory using a multi-valued memory that can protect written data against destruction upon a hit or the like during writing to a higher page. <P>SOLUTION: The memory system includes a first, volatile storage part, a second, nonvolatile storage part comprising an array of a plurality of memory cells capable of storing multi-valued data which have a plurality of pages, and a controller for implementing data transfer between the second storage part and a host device via the first storage part. The controller has a migration part 155 for, if data has been written in the lower page that is on the same memory cell as the page to which data are to be written on a write-once basis, backing up the data in the lower page before the data are written to the second storage part, and a destructive information recovery part 156 for, if the data in the lower page are destructed, recovering the destructed data by the use of the backup data. <P>COPYRIGHT: (C)2009,JPO&INPIT |
