Patent ID: 8756384

Claim:
A device comprising: a memory comprising a data area and a page management table of a plurality of pages for managing arrangement information of the data area, and a controller for controlling a data writing operation to the memory for writing data after erasure thereof, and for determining a page, of the plurality of pages, for holding valid arrangement information in accordance with a combination of statuses of said plurality of pages, wherein the plurality of pages includes a first page, a second page, and a third page, and wherein the controller starts a restoring operation of the data in the page corresponding to the data writing stage at the occurrence time of power shut-off operation, and when one of said first and second pages is valid and stable and a copy of a valid one of said first and second pages is written to said third page, determining that the data is interrupted at a stage from an erasure of an invalid one of said first and second pages to a rewriting operation to the valid page, and determining that one of said first and second pages whose copy is written to said third page is valid and restores the valid page.