Patent ID: 7953920

Claim:
A semiconductor storage device comprising: a first memory area provided in a volatile semiconductor memory which performs writing of data by a first unit or less, the first unit being an access unit to the semiconductor storage device; second, third, and fourth memory areas provided in a nonvolatile semiconductor memory which performs writing of data by a second unit and performs erasing of data by a third unit, the third unit being twice or larger natural number times as large as the second unit; and a controller executing: a first processing for storing a plurality of data by the first unit in the first memory area; a second processing for storing data outputted from the first memory area by a first management unit in the fourth memory area, the first management unit being twice or larger natural number times as large as the first unit and being less than the third unit; a third processing for storing data outputted from the first memory area by a second management unit in the third memory area, the second management unit being twice or larger natural number times as large as the first management unit; a fourth processing for selecting an area of the third unit in the fourth memory area and for moving the selected area to the second memory area; a fifth processing for selecting data in the fourth memory area, copying the selected data to an area of the third unit having empty areas of the second unit, and allocating the area of the third unit to the second memory area; and a sixth processing for selecting data in the second memory area and copying the selected data to an empty area of the third unit in the second memory area.