NONVOLATILE SEMICONDUCTOR STORAGE DEVICE

PROBLEM TO BE SOLVED: To avoid an abnormal state such that a system becomes out of action by the breakage of data important for the system in a nonvolatile semiconductor storage device such as flash memory. SOLUTION: This device has a substitution processing function for performing the substitution by a memory cell group containing no defective memory cell, a rewrite frequency averaging processing function for grasping the data rewrite frequency of each memory cell group and substituting a plurality of memory cell groups so as not to generate an extremely large difference in rewrite frequency between the memory cell groups, and an error correcting function for detecting and correcting an error of the data stored in a memory array. The first address conversion information by the alternate processing function and the second address conversion information by the rewrite frequency averaging processing function are stored in prescribed areas of the memory array, so that a plurality of pieces of the first address conversion information and second address conversion information related to the same memory cell group are stored in time series. COPYRIGHT: (C)2004,JPO