Patent ID: 8447914

Claim:
A memory system comprising: a nonvolatile semiconductor memory area including a plurality of parallel operation elements respectively having a plurality of physical blocks, each of the plurality of physical blocks being a unit of data erasing; and a controller configured to drive the parallel operation elements in parallel and configured to manage a number of times of erasing in logical block units, each of the logical block units being associated with a plurality of physical blocks driven in parallel; wherein the controller is configured to perform physical block replacement processing for replacing, when a bad block managed in physical block units occurs in the logical block, the bad block with another physical block in a same parallel operation element, and thereafter acquire a free block as an unallocated logical block and execute replacement of a logical block address of the acquired free block and a logical block address of a logical block subjected to the physical block replacement processing, the controller includes a free block management table for managing a logical block address of a logical block allocated to the free block and a logical-to-physical translation table for managing, in logical block address units, a correspondence relation between a plurality of physical block addresses corresponding to a plurality of physical blocks and logical block addresses corresponding to logical blocks associated with the physical blocks and the number of times of erasing and an erasing time; and, the free block management table includes a first list for managing, in erasing time order managed by the logical-to-physical translation table, the logical block address for the logical block allocated to the free block and a second list for managing, in order of a number of times of erasing managed by the logical-to-physical translation table, a logical block address for a logical block overflowing from the first list, and the controller acquires the free block from the second list.