Patent ID: 8381023

Claim:
A memory system comprising: a plurality of first blocks that store information including user information, wherein first physical addresses that do not overlap one another are respectively assigned to the plurality of first blocks; a plurality of second blocks that respectively store first physical addresses of initial defect blocks out of said plurality of first blocks; a plurality of user information blocks, out of said plurality of first blocks, that store said user information; a plurality of duplicated user information blocks, out of said plurality of first blocks, that each store a duplicate of said user information; and a computing device that finds a first physical address corresponding to a given logical address that provides access to a user information block, wherein said computing device has, as information, mirror logical addresses for accessing said plurality of duplicated user information blocks, any one of the mirror logical addresses having a one-on-one correspondence relationship with the given logical address, said computing device finds said first physical address corresponding to said given logical address based on said given logical address and the information stored in said second blocks, determines whether or not a first block specified by the found first physical address is a tentative late defective block and, when it is determined that said first block is said tentative late defective block, finds said first physical address corresponding to said given logical address again, based on said given mirror logical address corresponding to said given logical address and the information stored in said second blocks, second physical addresses that do not overlap one another are respectively assigned to said plurality of second blocks, said first physical addresses of said initial defect blocks stored in said plurality of second blocks are stored in said plurality of second blocks in the order of said second physical addresses in accordance with the order of said first physical addresses, said computing device, when finding said first physical address corresponding to said given logical address again, based on the given mirror logical address corresponding to said given logical address and the information stored in said second blocks, (A) searches a target block from said plurality of second blocks using said given mirror logical address; (B) finds a number of the plurality of first blocks, existing before a first physical address of an initial defect block read from said target block, other than said initial defect blocks, based on said first physical address of said initial defect block read from said target block, and said second physical address of said target block; and (C) finds said first physical address corresponding to said given logical address, based on said given mirror logical address and said number.