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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    ◄SCREEN►    ◄Screen Modes►
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