Importance

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Abstract

A semiconductor memory device is provided with a memory cell array including memory cells being arranged in a shape of matrix and requiring a refresh operation. In the semiconductor memory device, a control circuit controls a timing of the refresh operation in accordance with an internal signal independently of an external signal and controlling the memory cell array in a non-normal operation mode different from a normal operation mode for writing data into the memory cell array and reading out data from the memory cell array. The control circuit starts the non-normal operation mode in response to a sequence of entry into the non-normal operation mode based on a predetermined first command signal, sets the non-normal operation mode in response to a sequence of setting the non-normal operation mode based on a predetermined second command signal, and thereafter, executes operation of the corresponding non-normal operation mode which is set.

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First Claim