| 摘要 |
PURPOSE:To prevent vanishing of information and to improve reliability of a system by detecting previously a cell transistor having possibility of vanishing of information with such circuit constitution that increasing of an element area and increasing of manufacturing cost as the case of incorporating a ECC circuit do not occur, and obtaining a chance in which rewriting and changing of a cell transistor used are performed. CONSTITUTION:Such circuit constitution is made that a sense point of a sense circuit 12 for detecting variation of memory condition > a sense point of a sense circuit 9 for output > a sense point of a sense circuit 13 for detecting variation of memory condition, by comparing output values of these sense circuits 12, 9, 13, a cell transistor which decrease electric charge stored in a floating gate is detected. |
