Compatibility: VGA
Expects: AX    1010H
BX    color register to set (0-255)
CH    green value (00H-3fH)
CL    blue value  (00H-3fH)
DH    red value   (00H-3fH)
                                                                  
Returns: (none)
                                                                  
Info: This sets a specified DAC color register on a VGA card to a
specified 18-bit value.  It allows you to make very subtle
changes to color settings--the VGA can display 256 of the 262,144
different colors at once (when in a 256-color video mode).

BX selects one of the 256 DAC color registers (00H-ffH).  The high-
order 8 bits are ignored.

In text modes, DAC registers 00-0fH normally represent palette
registers 00-0fH (and thereby affect the color settings of text-
mode video attributes).  You can use INT 10H 1013H to set the 256
color registers as 16 banks of 16 colors and then activate any of
the 16 banks for instant redefinition of the entire palette.

DH,CH,CL are Red, Green, and Blue settings.  Only the low 6 bits of each
element are used, so each can range from 0 to 3fH (64 possible
shades).  Thus, there are 64x64x64=262,144 possible RGB settings.

Notes: Use INT 10H 1015H to obtain the RGB values of a DAC register.
Use INT 10H 1012H to set a block of DAC registers all at once.

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INT 10H 1010H: Set One DAC Color Register