Semiconductor memory device having data protection feature
First Claim
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1. A semiconductor memory device comprising:
- a plurality of memory block regions, each memory block region including at least one memory block for storing data in a nonvolatile manner, each memory block region storing data of a different attribute;
control circuitry for setting data rewriting protection status for said plurality of memory block regions on a region-by-region basis according to states of a plurality of external control signals, so that the protection status of one of said memory block regions can be made different from the protection status of another of said memory block regions.
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Abstract
A reset power down mode designating signal and first and second write protect signals are provided to a control circuit. According to the states of these external control signals, the status of unconditional inhibition, unconditional permission, and lock bit (LB) dependency for the protect status of data rewrite is set for each memory block group of a memory array. Therefore, the write protect status can be set in a flexible manner for a nonvolatile semiconductor memory device.
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Citations
9 Claims
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1. A semiconductor memory device comprising:
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a plurality of memory block regions, each memory block region including at least one memory block for storing data in a nonvolatile manner, each memory block region storing data of a different attribute; control circuitry for setting data rewriting protection status for said plurality of memory block regions on a region-by-region basis according to states of a plurality of external control signals, so that the protection status of one of said memory block regions can be made different from the protection status of another of said memory block regions. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A semiconductor memory device including a plurality of nonvolatile memory blocks, and having a write protect feature, comprising:
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lock bit storage sections corresponding respectively to said plurality of nonvolatile memory blocks, for storing lock bits indicating whether data rewriting of corresponding memory blocks is allowed; first and second write protect designating signal input pins, so that a write protect state of each of said plurality of nonvolatile memory blocks can be set on a region by region basis, the region including at least one memory block, through signals applied to the first and second write protect designating signal pins, the write protect state including a first mode in which allowance of data rewriting of a memory block is determined in accordance with a value of a corresponding lock bit and a second mode in which allowance of data rewriting of the memory block is determined regardless of the value of the corresponding lock bit.
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8. A semiconductor memory device, comprising:
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a plurality of memory block regions each including at least one memory block for storing data in a nonvolatile manner; a plurality of lock bit storage circuits provided corresponding to respective memory blocks of said plurality of memory block regions, for storing lock bits indicating whether corresponding memory blocks are allowed to rewrite storage data; mode setting circuitry for setting write protect status for the memory blocks on a region by region basis in accordance with a combination of states of a plurality of external control signals; protect control circuitry responsive to a data rewriting operation mode instructing signal for determining whether data rewriting of an addressed memory block is allowed in accordance with a block address signal addressing the addressed memory block, a value of a lock bit for the addressed memory block and an output signal of said mode setting circuitry. - View Dependent Claims (9)
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Specification