| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To rewrite written data partially without any erasure. <P>SOLUTION: The semiconductor nonvolatile memory performing rewrite operation for changing already written data partially by a simple method without erasure operation has a valid data storage section for storing a flag indicating which of data before rewrite and data after rewrite are valid, reads data corresponding to the supplied read address from a main memory cell array, when a first flag for validating data before rewrite are stored at the valid data storage section in read operation. When a second flag for validating data after rewrite is stored at the valid data storage section, if the read address agrees with the first address of the correspondence information, reads data at the second address corresponding to the read address from a sub-memory cell array, and if they do not agree, reads data at the read address from the main memory cell array. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
