Patent ID: 7543103

Claim:
A host apparatus controlling a memory system which has a nonvolatile semiconductor memory, the host apparatus comprising: an application configured to perform predetermined operations in accordance with a program and to issue a write function invocation; a file management system configured to allocate unit regions into which a memory area of the nonvolatile semiconductor memory is divided as a write area which stores write data, using management units each of which is natural-number multiple times as large as the unit region as units for determining allocation, and to allocate the management units as the write area in an order of realizable write speed of the management units when receiving the write function invocation, the realizable write speed of each of the management units being dependent on a distribution of unit regions to which data can be written within a corresponding management unit; and a controller configured to issue an instruction to the memory system to write the write data into the nonvolatile semiconductor memory in accordance with an instruction by the file management system.