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Miscellaneous          index 06h  GRAPH

Layout  b3-b2  MM   Memory map
        b1     COE  Chain odd/even
        b0     G/A  Graphics/alphanumerics mode

- Memory map (bits 3-2)
        The display memory is mapped into the host processor's memory
        address space. The starting location and the length of the
        display memory are set in this field.

                b3 b2   Location      Length
                0  0    A000h-BFFFh   128 kb    VGA
                0  1    A000h-AFFFh    64 kb    VGA + 2nd adapter
                1  0    B000h-B7FFh    32 kb    Hercules emul.
                1  1    B800h-BFFFh    32 kb    CGA emulation

- Chain odd/even (bit 1)
        0 : Standard VGA addressing.
        1 : Replace host address bit 0 with a higher-order address bit
            so that even host addresses access even planes and odd
            addresses access odd planes. Used for MDA emulation.

- Graphics/alphanumerics mode (bit 0)
        0 : Select the alphanumeric mode of operation.
        1 : Select the graphics mode of operation.