Patent ID: 7840617

Claim:
A host device comprising: a memory system including a nonvolatile semiconductor memory and a controller which controls the semiconductor memory, the memory system being provided into the host device; and a file management system which allocates a plurality of clusters defined in a file allocation table (FAT) file system to data to be written in the memory and which manages the allocated data by using a management data including a file allocation table (FAT) and a directory entry which are defined in the FAT file system, the directory entry including a root directory entry serving as entry information of a root directory of an uppermost layer and a sub-directory entry serving as entry information of a sub-directory belonging to the root directory, and wherein the file management system allocates the plurality of clusters in a predetermined range, the management data stored in a management data block is allocated to a logical address belonging to a first range from a lowest-order logical address and a file data stored in a file data block which is different from the management data block is allocated to the logical address belonging to a second range different from the first range, and the first range of the logical address is an overwrite logical address to which an overwrite is performed, and the second range of the logical address is an incremental write logical address to which an incremental write is performed.