Patent ID: 8416446

Claim:
An image forming device which allows a connection of an external memory device storing therein print data and file information corresponding to the print data, the image forming device comprising: a separate memory from the external memory device, the separate memory to store log file information associated with previously printed print data; a connecting part to connect the external memory device; a controller to store group file information in the separate memory that includes file information selected from among the file information received through the connecting part, to compare the log file information and the file information of the connected external memory device and to confirm whether the printing has been previously performed, and to determine whether the received file information matches with the group file information; and a display to display a comparison result of the log file information and the file information of the connected external memory device, wherein the external memory device is a portable memory device, and when the external memory device or other type of external memory device is re-connected to the image forming device, the controller reads from the memory the log file information and the group file information which correspond to the re-received file information transmitted through the connecting part from the re-connected external memory device or other type of external memory device, and displays the log file information and the read group file information through the display.