| 摘要 |
<p>PURPOSE:To detect the shortening of a storage holding time due to rewriting beforehand and to prevent disappearance of stored contents before the operator is aware of it, by generating an alarm when the number of times of rewriting for contents stored in a specific address exceeds an allowable value. CONSTITUTION:When rewriting is requested to an EAROM1, address An of the EAROM1 is read out and is stored temporatily in a rewrite number adding circuit 7. A control circuit 3 is operated to erase and rewrite contents in all addresses of the EAROM1. At this time, information obtained by adding +1 to contents before rewriting is written in address An by the circuit 7. Next, contents of address An is read out and are sent to a comparing circuit 5 and are compared with an allowable number of times of rewriting. If they exceed this allowable number of times of rewriting, an alarm is issued by an alarm circuit 6. Thus, the shortening of the storage holding time of the EAROM due to repetition of rewriting is detected.</p> |
