CONTROL METHOD FOR SEMICONDUCTOR MEMORY AND SEMICONDUCTOR MEMORY

PROBLEM TO BE SOLVED: To provide a non-volatile semiconductor memory which is inexpensive and of which the number of rewritable times is large. SOLUTION: A semiconductor memory 10 is provided with a flag bit 19 dividing a memory mat 11 of whole capacity R consisting of non-volatile semiconductor memory cells into plural blocks of size M and discriminating whether each block is rewritten or not, a block decoder 20 selecting a block being not yet rewritten as a block to be rewritten in accordance with a setting state of the flag bit 19, and a rewriting control logic circuit 18 erasing all blocks, that is, the whole memory mat 11 prior to initial rewriting after all blocks are rewritten, when it is assumed that the number of rewritable times is P and the number of division of the memory mat 11 is N, the large number of rewritable times of degree of P×N is realized by an inexpensive memory mat 11 of the number of rewritable times of degree of P.