| 摘要 |
PROBLEM TO BE SOLVED: To evade useless refreshing operation and to prevent lowering in access efficiency by counting the number of access times at every memory cell and executing refreshing. SOLUTION: A refreshing control circuit 10 counts the number of times of the write-in access and the read-out access of the first and second logic data to respective memory cells MC by first and second counters. Then, when either count value between the first and second counters exceeds a prescribed value, the circuit 10 outputs an address, and activates a refreshing start signalϕta. A main control circuit 9 executes the refreshing operation for a capacitor of the answering memory cell MC based on the address outputted from the circuit 10. Thus, since only the specified memory cell MC is refreshed, the useless refreshing simultaneously refreshing useless memory cells MC is eliminated, and a refreshing time is shortened also.
|
