| 摘要 |
PURPOSE:To improve the reliability of a memory protecting function by changing over an abnormal key data to other normal key memory through a changing-over circuit when a key memory checking circuit detects the abnormality at the key memory during the use. CONSTITUTION:In respective key memories 8, the same key data are stored, and when an access request in executed from a data processor, the key data of respective key memories 3 are read, the error checking is respectively executed at a key memory checking circuit 5 and respective key memories 3 are decided to be normal or abnormal. When a key memory 3 during the use out of these is abnormal, backing-up is executed by changing over a key data output to a normal key memory, and the reliability can be improved. The key memory and the memory device can be constituted in a pair, and for executing the LSI operation of an element or for a circuit constitution, the mass production can be obtained.
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