| 摘要 |
<p>PROBLEM TO BE SOLVED: To keep the precise data and to secure reliability in a system by periodically re-programming a charge loss much for a once programmed memory element and refreshing it. SOLUTION: When a program is stored in a specified area of a memory block 220 as a result of read-out, an EPROM write-in mode is set, and a sense amplifier means 230 re-programms the data on a data bus DB in the relevant area of the memory block 220. At a normal operation mode time, a count enable signal CNTEN' is outputted at every a prescribed time by a timer 281, and when an address CAO of an address selection part 260 is enabled, a read-out mode is set, and the data in the memory block 220 are read in, and only when the data are stored, the write-in mode is set, and refresh operation is performed. Thus, the refresh is performed only for a cell programmed from an original program mode.</p> |
