PURPOSE: To efficiently fetch the change condition of an input analog signal to an external memory by generating a sampling command signal each time the differential value of the A/D converting data of an input analog signal exceeds a prescribed value.

CONSTITUTION: The title generator is composed of an A/D converting part 10 and a pulse generating part 20. An input analog signal is sent to the pulse generating part 20 converted to the digital data by the A/D converting part 10. The pulse generating part 20 calculates the differential value of the introduced data and generates a pulse-shaped output each time it exceeds the value specified beforehand. The pulse-shaped output is impressed to a memory as a sampling command signal, and when the data of the A/D converting part are introduced into the memory, the data are stored each time the sampling command signal is impressed. Thus, without enlarging the memory capacity, the generator of the sampling signal to fetch the data, in which the input signal can be faithfully reproduced, is obtained.