| 摘要 |
<P>PROBLEM TO BE SOLVED: To detect the number of fail bits at a high speed. <P>SOLUTION: A nonvolatile semiconductor memory in accordance with one embodiment comprises: an accumulator 12 that divides first unit data into z pieces of second unit data and accumulates fail bits for each second unit data; and a controlling circuit 10 for controlling detection operation of the fail bits after writing. The controlling circuit 10 accumulates the fail bits for each second unit data by: causing a sense amplifier SA0 to store third unit data out of each second unit data; reading out each second unit data for one bit at a time until the sum of z bits in parallel from the sense amplifier SA0; detecting the fail bits from the z bits by using a detecting circuit DTCT0; and transferring the z bits to the accumulator 12. <P>COPYRIGHT: (C)2013,JPO&INPIT |
