INT 10 - VESA SuperVGA BIOS v1.1+ - GET/SET DISPLAY START
        AX = 4F07h
        BH = 00h (reserved)
        BL = function
            00h set display start
                CX = leftmost displayed pixel in scan line
                DX = first displayed scan line
            01h get display start
                Return: BH = 00h
                        CX = leftmost displayed pixel in scan line
                        DX = first displayed scan line
Return: AL = 4Fh if function supported
        AH = status
            00h successful
            01h failed
Note:   this function is valid in text modes, provided that values are
          multiplied by the character cell width/height
SeeAlso: AX=4F01h,AX=4F05h,AX=4F06h

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