| 摘要 |
<p>PURPOSE:To obtain a nonvolatile semiconductor storage device capable of rewriting and erasing data in block units by dividing a memory cell array into a plurality of blocks, and by storing the status of each block into the same.' CONSTITUTION:With respect to each of four memory cell blocks from 110 to 113, the status as to whether data is already written or erased is stored in the form of one bit data in a corresponding circuit of status memory circuits 200, 210, 220, and 230. As for one arbitrary memory cell block, the status of data can be known by the readout of data from one memory cell of the status memory circuit. The period of this readout is the period for reading data from the memory, and hence it is significantly short. As a result of this, it is possible to rewrite and erase data of each memory cell without the increase of an access time.</p> |
