| 摘要 |
<p>A nonvolatile semiconductor memory includes a matrix of nonvolatile erasable memory cell transistors (108). A write or erase verify operation is carried out on one of the memory cell transistors (108) after that transistor has had information written therein (or erased therefrom), for determining whether or not that information has been written (or erased) sufficiently such that in a subsequent read operation the transistor is read as being in a written (or an erased) condition even when a power source voltage applied to the memory exhibits variation. The verify means (113) includes: storage means (115) operable, during a predetermined detection period commencing following a write (or an erase) operation, to store one or more output signals (S102) of a sense amplifier (112) connected to the memory cell transistor (108) involved in the write (or erase) operation concerned; decision means (126-128) operable to employ the or each output signal stored in the storage means (115)to determine whether or not the write (or erase) operation was sufficient; and repeat means operable, when the determination by the decision means is that the write (or erase) operation was not sufficient, to cause that operation be repeated. <IMAGE></p> |
