the computer 60 and its respective applications under the windowing system provides output 100 to a display 64 on the screen of which will be displayed the various images 106 108 etc as desired in a windowed environment also similar to the prior art system of fig1 a sequencer and d a converter 102 is provided which receives various stored images resulting from execution of the applications on line 98 from the memory to be described and outputs them on line 100 to the display 64 a closer comparison of fig2 to fig1 however reveals significant differences provided by the invention first a system accessible memory 74 is provided each application 66 70 in accordance with the invention assumes control over a portion of such memory 74 entirely for its own functioning each such portion of memory will comprise the virtual display adapter for each respective application whereby the application may independently declare such apportioned memory to represent any adapter type or mode required by the particular application thus a plurality of different such memory requirements associated with respective applications is shown at reference numerals 76 78 80 and 82 more particularly a first application 66 may require a display type mode of 640 u00d7 480 pixel resolution and a color palette managed by 8 bit byte words this requirement is reflected by the portion of system accessible memory 74 shown at reference numeral 76 this application 66 will further as an illustration require yet a different mode of display namely a 320 u00d7 240 resolution yuv 9 bit image shown at reference numeral 78 in like manner a second application 68 may require a different format such as 512 u00d7.