SEMICONDUCTOR STORAGE DEVICE

PROBLEM TO BE SOLVED: To attain improvement in writing speed and a longer life in a multivalue flash memory. SOLUTION: In the semiconductor storage device, a nonvolatile memory includes a plurality of blocks, each of the blocks includes a plurality of pages, and each of the pages includes a plurality of cells. The page is writable in a first mode for recording a plurality of bits in one cell, and the page is also writable in a second mode for recording bits smaller in number of the plurality of bits in one sell in a time shorter than the time required for writing in the first mode. A controller writes data to a first page by use of the second mode in response to a write request of data from the outside of the semiconductor storage device, and writes a part of data in the first page to the second page by use of the first mode. COPYRIGHT: (C)2010,JPO&INPIT