INT 10h,  0Ch (12)       Write Pixel

Writes a pixel dot of a specified color at a specified screen
coordinate.

On entry:      AH         0Ch
AL         Pixel color
CX         Horizontal position of pixel
DX         Vertical position of pixel
BH         Display page number (graphics modes with more
than 1 page)

Returns:       None

Registers destroyed:      AX, SP, BP, SI, DI

                                                                          
                             Legal values

  Mode   CX (Horizontal)  DX (Vertical)   AL (Pixel Color)   BH (Page Number)
04h      0-319            0-199             0-3
05h      0-319            0-199             0-3
06h      0-639            0-199             0-1
0Dh      0-319            0-199             0-15                  0-7
0Eh      0-639            0-199             0-15                  0-3
0Fh      0-639            0-349             0-1                   0-1
10h      0-639            0-349             0-15                  0-1
                                                                          

Notes:         If the pixel color (AL) is specified with bit 7 set,
the color bits of the pixel are XORed with the color
bits of the current pixel at the specified
coordinate. You can use this feature to write
characters and then erase them.

For modes 0Dh through 10h, a page number needs to be
supplied in BH.

See also: INT 10h, 0Dh

INT 10h, 0Ch (12) Write Pixel