NONVOLATILE MEMORY, MEMORY CONTROL UNIT, MEMORY CONTROL SYSTEM, AND NONVOLATILE MEMORY CONTROLLING METHOD

摘要

PURPOSE: A nonvolatile memory, a memory control unit, a memory control system and a method for controlling the nonvolatile memory are provided to improve the reliability of data by maintaining the writing state of the memory cell with lower power value than a predetermined critical value. CONSTITUTION: A memory cell array(2) comprises a plurality of memory cells with a floating gate A first sense amplifier(3) judges the voltage value of the floating gate and a first critical value that identifies the writing state and the erasing state of the memory cell. A second sense amplifier(4) judges the voltage value of the floating gate and a large critical value than the first critical value. A writing unit(5) again writes data of the memory cell with the floating gate whose voltage value is larger than the second threshold value. A data reader reads the data of the block of the designated address of the memory cell array. A temporary memory unit temporarily memorizes data.