| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce a circuit area and to shorten a verifying time by simplifying a control circuit and reducing the number of commands. SOLUTION: In automatic writing, a bit indicating whether writing operation (including writing operation before erasing) is finished in a state of writing-OK or not (PVOK) is set to '0', a bit indicating whether erasing operation is finished in a state of erasing-OK or not (EVOK) and a bit indicating whether automatic convergence operation is finished in a state of automatic convergence-OK or not (LCKOK) are set to '1', and a memory cell is selected by an address latched to an address register. That is, a sub-routine of writing before erasing (step ST5) is performed in a state in which an address is fixed. Sub-routines of erasing (step ST9) and self convergence (step ST13) are not performed. In erasing, PVOK, EVOK and LCKOK are all set to '0', memory cells are successively selected by an internal address of an address counter. That, is, writing before erasing, erasing, self convergence are performed for each memory cells selected by the internal address.</p> |
