To provide a display device capable of editing data for image display anywhere by using original data only if there is a compatible PC.

In a computer system comprising (1) a PC main body having software for data preparation for image display which prepares data for image display from original data stored by a display device, an operation processing part and a PC inputting-outputting part for performing data communication with an external device and (2) the display device having a display device side connecting part for performing data communication with the PC main body, software for image display, data of image display and a display device memory part for storing the original data, the control to display on a displaying part by using the data for image display stored in the display device memory part is carried out when the display device is not connected to the PC main body, and the operation processing part performs controls the display device memory part to store the data for image display and the original data as a set in the display device memory part when the display device is connected to the PC main body.