| 摘要 |
<p>PURPOSE: To obtain a storage device capable of avoiding an erasure-fault cell even if it occurs, by detecting the existence or nonexistence of the erasure-fault cell at every time of rewriting of a memory cell and by writing in data with the phase shifted to be normal or inverted. CONSTITUTION: It is checked up whether or not the address number of a memory cell wherein an excessively erased cell occurs, is present in latches RG1-RGn in an address latch circuit 3. In the case where it is not present, data for rewriting stored in an external data area 4 are read out sequentially and written in an appropriate place of a flash memory array, with the phase thereof so held as to be shifted to be normal. Information on the phase shifted to be normal is written in a phase information part 1a of the memory array. In the case where the address number is present, to the contrary, the data to be written in the memory cell wherein the excessively erased cell occurs are read out from an appropriate place of the external data area 4 and stored in a data latch circuit 5.</p> |
