INT 10H 1013H: DAC Color Paging Functions

                                                          Compatibility: VGA 
 Expects: AX    1013H
          BL    subfn: 00H = select color paging mode
                             BH = paging mode
                                  00H = 4 blocks of 64 registers
                                  01H = 16 blocks of 16 registers

          BL    subfn: 01H = activate color page
                             BH = DAC color page number
                                  00H-03H (4-page/64-reg mode)
                                  00H-0fH (16-page/16-reg mode)
 Returns: (none)
    Info: This lets you choose a DAC color-paging mode to enable groupings
          of color registers.  It also lets you activate a particular DAC
          register page.

          Text-mode users will prefer 16-color paging mode (BX=0100H),
          making it possible to quickly map any of 16 color set to the 16
          possible text-mode attribute colors.

          For instance, imagine setting up 16 groups with gradually-
          increasing brightness of all colors.  Then you could cycle
          through the groups (BX=0001H, BX=0101H, BX=0201H...) to brighten
          or dim the entire screen.

   Notes: Use INT 10H 101aH (query color paging state) to obtain the
          current settings.

See Also: INT 10H 10H: EGA/VGA Palette Functions
          INT 10H: Video Services
          EGA/VGA Data Areas
          VGA I/O Ports