To improve reliability by making a normal block, which is the subject of rewrite processing, and a fixed block, which is not the subject, preliminarily correspond to each other, and in the case where the rewrite processing is applied to the normal block, executing data refresh processing for the fixed block corresponding to that normal block.
A block split memory 201 consists of a normal block area 202 of normal blocks 1-17, alternative block area 203 of preliminary alternative blocks 1-8, and fixed block area 204. The alternative block area 203 is used in place of the block that has initial defects generated in the memory 201 or defects formed through deterioration. In addition the normal blocks 1-5 are corresponding block in which defect registration blocks 1-4 and a system information block 206 are made to correspond to each other preliminarily. With the number of times of rewrite in the normal blocks 1-5 reaching a prescribed number, a control circuit executes data refresh processing of the corresponding block, thereby improving reliability.
KATAYAMA KUNIHIRO
TAMURA TAKAYUKI
