SEMICONDUCTOR MEMORY DEVICE, CONTROL METHOD THEREOF AND INFORMATION PROCESSING UNIT

摘要

PROBLEM TO BE SOLVED: To accurately determine whether a storage area for an indicated capacity can be reserved, when the number of physical blocks constituting a logical block is variable.SOLUTION: The number of free blocks, which are unused logical blocks in a nonvolatile semiconductor memory, is calculated. A capacity of the logical block in the nonvolatile semiconductor memory is converted into a first management unit whose size is equal to or smaller than the size of a physical block and is larger than the size of a sector, and the number of pieces of usable data in the first management unit is calculated. When at least one of a first condition in which the calculated number of free blocks is below a first threshold and a second condition in which the calculated number of pieces of data in the first management unit is below a second threshold is satisfied, it is determined that there is a failure, and the mode is changed to a failure mode.