Patent ID: 8914702
Filing Date: 2014-12-16
Classification: G06F,G11C

Abstract:
1. A method of repairing a bit error which occurs due to a change of bit data stored in a first nonvolatile semiconductor memory, comprising: a) temporarily storing data which is stored in said first nonvolatile semiconductor memory when said data is read by a host system; b) judging whether an error exists in said temporarily stored data and correcting the error if there is; c) temporarily storing, into a storage part, error information that identifies a page of the first nonvolatile semiconductor memory corresponding to the temporarily stored data; d) in response to an instruction by the host system, storing said error information from the storage part into at least one of an unused area in said first nonvolatile semiconductor memory and a second nonvolatile semiconductor memory at such a predetermined timing that no suspension or delay occurs in reading of data by the host system; e) once at a predetermined timing, reading, from the first nonvolatile semiconductor memory, a block of data including the page of the first nonvolatile semiconductor memory identified in the error information, correcting the error, and then rewriting said block of data with the corrected error into said first nonvolatile semiconductor memory; and f) deleting the error information from at least one of the unused area in said first nonvolatile semiconductor memory and the second nonvolatile semiconductor memory.