A digital multifunction device is provided with RAM having a virtual drive area. The digital multifunction device enables a personal computer connected to and capable of communicating with the digital multifunction device via a USB interface to recognize this virtual drive area as an external storage device. When the personal computer writes image data to the virtual drive area, the digital multifunction device selectively executes one of an image forming process, fax transmitting process, and mail transmitting process based on the type of folder in which the image data is written. Accordingly, image data in a first folder is printed on recording paper, or image data in a second folder is transmitted to an external facsimile machine.