Abstract: A printer used as an output unit for a personal computer or the like is characterized by having a memory unit including a first memory area for storing input data and a second memory area for storing image data obtained by developing the input data, the first memory area and the second memory area being arranged within one and the same memory space to form the memory unit, and by having an area control unit for changing a proportion of the capacity of the second memory area within the memory unit to alter the relative proportions of the first memory area and the second memory area in the memory space forming the memory unit. A print unit included in the printer fetches the image data from the second memory area and performs printing in accordance with the fetched image data.