DATA DISPLAY DEVICE

PROBLEM TO BE SOLVED: To provide a data display device which does not require the saving/ rewriting of picture element data on a part hidden by the overlap of windows and which can execute a high speed processing. SOLUTION: Video memories 1a-1c holding picture element data of windows are hierarchically stored in a video memory stack 11. The video memories are managed by a video memory management means 12. A host bus interface means 13 newly secures the video memory at the time of plotting the new window. Display position information on the screen of a monitor 4 is preserved with picture element data on the video memory. The pertinent video memory is positioned on the highest stage of the video memory stack and picture element data on the respective video memories are synthesized by a video synthesis means 14.