NONVOLATILE SEMICONDUCTOR STORAGE DEVICE

摘要

PURPOSE: A nonvolatile semiconductor storage device in which multilevel information is to be stored in one memory cell by setting a plurality of thresholds. CONSTITUTION: The each bit of data composed a plurality of bits is separately written on and read from one memory cell and the data are erased, in accordance wth address signals or control signals. Specifically, a memory array is accessed in accordance with three dimensional addresses of X,Y,and Z addresses and a plurality of bit data in one memory cell can be recognized with the Z address.