Patent ID: 6879528

Claim:
A control method of a nonvolatile memory having a plural number of blocks, wherein said block has a plural number of pages, said page has data area for writing data and redundant area, said redundant area of initial said page of said block has a block data invalidation flag indicating whether said data written in the block are invalid or not and indicating that said data are not invalid at the state that the nonvolatile memory is erased, and said redundant area of last said page of said block has a block data validation flag indicating whether said data written in the block are valid or not and indicating that said data are not valid at the state that the nonvolatile memory is erased, having: a data writing step of writing data in said data area; and a validation step of making said block data validation flag of said block having said data area in which said data are written to indicate that said data are valid.