PURPOSE: To emininate a waste of operation cycle time by controlling the operation of a machine according to previously stored designated size data when a paper cassette of a wide use is mounted.

CONSTITUTION: A control unit is adapted to control a machine capable of operating with a paper cassette capable of storing sheets of different size for a wide use and operating corresponding to a size code of a special cassette having a code corresponding to each sheet size. Means SW300WSW307 for discriminating a size code of a paper cassette are mounted on a machine body. Means RAM203 for storing designated size data separately from a size code of a paper cassette is provided. The first CPU201 is adapted to detect that a cassette of wide use is installed, and the second CPU202 is adapted to control the operation of the machine according to a size code of a paper cassette and control the operation of the machine according to the stored size data on detecting that a cassette of a wide use is used.