A specifying circuit specifies either the first masking method or the second masking method. A first generation circuit generates a signal corresponding to the first method. A second generation circuit generates a signal corresponding to the second method. A third generation circuit generates a write pulse signal on the basis of the output signal of the first generation circuit in response to the specification of the first masking method made by the specifying circuit and on the basis of the output signal of the second generation circuit in response to the specification of the second masking method made by the specifying circuit.