Importance

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Abstract

A semiconductor memory device, divided into plural blocks, comprising: a memory array having a non-volatile memory element which makes the read cycle and the write cycle to be substantially equivalent; plural storage elements storing the information of write protection/permission corresponding to each said block respectively; and a setting circuit to set the information of write protection/permission to said plural storage elements, wherein said setting circuit sets the write-protection information to said plural storage elements at the write cycle after designated plural read cycles. Therefore, the write protection/permission can be set by the unit of block, block by block, so that the write-protected ROM and the RAM can be set freely. Furthermore, the complexity of the setting procedure of write protection/permission may prevent the accidental false setting caused by a system runaway and so forth.

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First Claim