Use bits-per-pixel-per-plane and planes values to determine the required size of the array that holds a graphics screen image. Bits-per-pixel-per-plane and planes values, along with the horizontal resolution, also determine which screen modes are compatibile: Horizontal Bits-per-pixel- resolution Screen mode per-plane Planes (in pixels) ----------- --------------- ------ ----------- 1 2 1 320 2, 4, 11 1 1 640 3 1 1 720 7 1 4 320 8, 9(> 64K video memory), 12 1 4 640 9(64K video memory), 10 1 2 640 13 8 1 320 The following formula gives the required size, in bytes, of an array used to hold a captured image: size% = 4 + INT(((PMAP (x2!, 0) - PMAP (x1!, 0) + 1) * (bits-per-pixel-per-plane%) + 7) / 8) * planes% * (PMAP (y2!, 1) - PMAP (y1!, 1) + 1) GET and PUT operations are compatible in screen modes with the same horizontal resolution and bits-per-pixel-per-plane and planes values. For example, screen modes 2, 4, and 11 are compatible, and screen modes 8 and 12 are compatible. See Also