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Mode control reg.      index 10h  ATTRIB

Layout  b7     IPS  Internal palette size
        b6     PCS  Pixel clock select
        b5     PPC  Pixel panning compatibility
        b4          Reserved
        b3     B/I  Enable blink or intensify
        b2     ELG  Enable line graphics character codes
        b1     DT   Display type
        b0     G/A  Graphics / alphanumerics mode

- Internal palette size (bit 7)
        0 : The palette registers's bits 4 and 5 provide the address
            bits 4 and 5 to the Color registers.
        1 : The C45 field of the Color select register provides the
            address bits 4 and 5 to the Color registers.

- Pixel clock select (bit 6)
        Controls the clocking of the PELs to allow eight bits of data
        to select a color in mode 13h. This field is used in
        conjunction with the Shift register (SR) field of the Mode
        register. When the SR field is set to 2, data is loaded into
        the shift registers in two operations, providing 8 bits of
        data from each display plane. This value of 2 is operative
        only during mode 13h. During this mode, the PCS field is set
        to 1.
        0 : The pixel data is changed at each cycle of the dot clock.
        1 : The pixel data is changed every second cycle of the dot
            clock.

- Pixel panning compatibility (bit 5)
        This field allows a section of the screen to be panned
        independently from the second section during a split-screen
        mode of operation.

        0 : Prevents a line compare from affecting the output of the
            Horizontal pixel panning register.
        1 : Allows a line compare to affect the output of the
            Horizontal pixel panning register and the Byte panning
            field of the Preset row scan register.

- Enable blink or intensify (bit 3)
        0 : Use bit 7 of the character attribute code to select a
            background color. Do not allow blinking.
        1 : Use bit 7 of the character attribute code to enable or
            disable blinking. This is the default mode of operation.

- Enable line graphics character codes (bit 2) (text modes)
        0 : Set the ninth dot of the character to the background
            color, regardless of the character code.
        1 : Set the ninth dot of the character to the same value as
            eighth dot of the character for all graphics line
            characters.

- Display type (bit 1)
        0 : Select color display attributes.
        1 : Select IBM monochrome display adapter attributes.

- Graphics/alphanumerics (bit 0)
        Selects whether the display is in an alphanumeric (text) or
        graphics mode. In the VGA, this field should be the same value
        as the G/A field in the Miscellaneous register.

        0 : Select alphanumeric mode.
        1 : Select graphics mode.