Compatibility: All
Expects: AH    0cH
AL    color number (+80H means XOR with current value)
BH    video page (0-based)
CX    graphics column
DX    graphics row
                                                                  
Returns: (none)
                                                                  
Info: Even on the FASTEST computers, this fn is WAY TOO SLOW to expect
to get any reasonable amount of drawing done.

The BIOS does not support line-drawing or other standard graphics
primitives.  To draw graphics with reasonable speed, you must
access video memory directly.  See Video Memory Layouts.

Notes: When you add 80H to the color value in AL, the specified color is
XORed with the color that is currently at that position.  That is
a useful graphics operation since XORing the same value twice
ends up with the original value.

See Also: INT 10H 0dH (read graphics pixel)
- -

INT 10H 0cH: Write Graphics Pixel