DISPLAY INTERFACE DEVICE

PROBLEM TO BE SOLVED: To realize a frame buffer memory retreat/return processing system by division data transfer control. SOLUTION: A data transfer between an incorporated frame buffer memory 12 and a system memory 5 is executed by a graphic board 1 incorporated graphic controller 11, and the data transfer between a pixel data area and a pixel data reservation area is controlled by the controller 11, and retreat/ return processing is performed for the display area pixel data on a video display 2 picture. The graphic controller 11 stores left upper corner addresses, widths, heights of pixel data small areas A, B,..., N secured on the frame buffer memory 12 and specified addresses and the number of entry by a relevant screen address table in respective incorporated registers. The controller 11 compares respective small area pixel data and address data by the frame buffer memory 12 with relevant cache buffer contents by incorporated comparison circuit and cache buffer to output them.