Kabushiki Kaisha Tokai Rika Denki Seisakusho

Hidekazu Adachi

Tetsuya Egawa

Kazunori Arakawa

Yosuke Ohashi

Different block management values that sequentially increase are set for a plurality of blocks to indicate active states of the blocks. For example, a first block management value '$1111' is stored in a first block, and a second management value '$1112' is stored in a second block. Thus, even when more than one block is in an active state, an updated value is read from the block that stores a larger block management value. This allows for the true updated value to be read.

Flash memory device

In a flash memory device, after an updated value is copied from a first block to a second block, a block management value of the first block is set to an unused state, and maintenance is performed to erase data from the first block. When performing maintenance, the block management value of the first block Bis rewritten from '$FFF0' to '$FFFF.' When a reset occurs and the power supply is deactivated during the maintenance, the digit of &#x201c;$0&#x201d; in the block management value may become &#x201c;1&#x201d; to &#x201c;E&#x201d; of the hexadecimal system. In this manner, when the block management value includes a single digit of &#x201c;1&#x201d; to &#x201c;E&#x201d; and three digits of &#x201c;F,&#x201d; the reading of an updated value from the block corresponding to the block management value is restricted.

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Aichi, Japan

Hidekazu Adachi