| 摘要 |
<p>A plurality of flags are formed so as to correspond to respective memory cell groups, each consisting of a plurality of volatile memory cells. Each flag indicates that the memory cell contains data in a second storage mode. When the first storage mode in which each memory cell holds data is switched to the second storage mode in which memory cells of each memory cell group holds the same data, each flag is reset in response to the first access of the corresponding memory cell group. For this, in each memory cell group, only the first access is performed in the second storage mode. In the aforementioned switching operation, by accessing a memory cell by the mode in accordance with the flag, a system managing the semiconductor memory can freely access the memory cell even during the switching operation. As a result, it is possible to substantially eliminate the switching time.</p> |
