Patent ID: 7962688

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, fourth, and fifth 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 fifth memory area, the second management unit being twice or larger natural number times as large as the first management unit and being less than the third unit; a fourth processing for moving an area of the third unit having the oldest allocation order in the fourth memory area to the second memory area; a fifth processing for selecting valid data in the second memory area and copying the selected valid data to an empty area of the third unit in the second memory area; a sixth processing for moving an area of the third unit having the oldest allocation order in the fifth memory area to the third memory area; and a seventh processing for selecting valid data in the third memory area and copying the selected valid data to an empty area of the third unit in the third memory area.