| 摘要 |
PURPOSE:To operate a memory device normally even if any one of plural bank registers is failed by switching the failed bank register automatically by a stand-by bank register. CONSTITUTION:When any one of the bank registers 20-23 is failed and any one of selecting circuits 30-33 has an error, a common error register 431 holds logic '1' and the output of an OR gate 430 is turned to '1'. Any one of bank register setting signals S0-S3 is outputted to a NAND gate 405 through AND gates 400-403 and a NOR gate 430. The stand-by bank register 24 stores common bank information CD every system clock until the error is detected by error detecting circuits 410-413. When any one of the circuits 410-413 detects the error, the same information as that of the failed register out of the bank registers 20-23 is stored and then the stand-by register 24 continues to operate instead of the failed register out of the registers 20-23.
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