Nonvolatile memory comprising a circuit capable of memory life time recognizing

Abstract

A nonvolatile memory wherein remaining lifetimes of memory cells can be accurately determined is provided, the nonvolatile memory includes: plural memory cell groups, assigned with respective addresses, arranged for respective words and used for storing one word of data; plural dummy cell groups also assigned the respective addresses and having different ranks of rewriting lifetimes; a writing circuit which, when writing data into a memory cell group having a given address, also writes the data into a dummy cell group having the same address at the same time; a lifetime recognizing circuit which recognizes an estimated number of past writing times by determining whether each dummy cell group can be successfully accessed; and a control section which controls operations of the memory cell groups and the dummy cell groups in response to an externally given command.