The nonvolatile semiconductor memory device of the present invention includes a memory cell array wherein data is stored in a nonvolatile state based on a difference in memory information between two memory cells comprising a memory cell pair, and a writing controller for writing data to the memory cell...http://www.google.de/patents/US7362617?utm_source=gb-gplus-sharePatent US7362617 - Nonvolatile semiconductor memory device and method of rewriting data thereof
