| 摘要 |
<p>PURPOSE:To improve the reliability of writing erasing by dividing a memory array into several blocks and sequentially using them when a memory capacity to be used is small. CONSTITUTION:When the fuse of a fuse circuit 13 is disconnected, a division circuit 10 is activated. An X-decoder 3, a Y-decoder 4 and a Y-gate circuit 5 are respectively divided into several equal number and only one group is activated. The others are not activated. When the number of writing/erasing times reaches a prescribed value, a switching circuit 11 operates and the division circuit 10 switches the D-decoder 3, the Y-decoder 4 and the Y-gate circuit 5 so that one to remaining equal divided parts of the memory array 1 is selected. A signal is transmitted to a counter circuit 12 and a memory for counter 14 is switched to other groups. When the unused part of the memory array 1 is selected, writing/erasing can furthermore be executed. Thus, the number of writing/erasing times can be improved for a reduced capacity when the all memory capacity is not required.</p> |
