| 摘要 |
PURPOSE:To prevent the accumulation of errors of data read out in a rare case by readling all data out of memory cells within a definite time during refreshing operation, and by correcting and rewriting erroneous data in a memory if it is detected. CONSTITUTION:In refreshing operation, a refresh address generating circuit (composed of refresh counter 23 and refresh address register 24) generates cyclically a column address for selecting readout data bits and a chip selection address and, while reading all memory contents of memory part 21, detects 28 an error of the readout data; erroneous data is corrected 31 and the corrected data and a check bit are rewritten together in the address where the error occured. Therefore, even an error of data read out of an address read out in a rare case is corrected and the accumulation of errors is prevented. |
