INT 10 - VESA SuperVGA BIOS - CPU VIDEO MEMORY CONTROL
        AX = 4F05h
        BH = subfunction
            00h select video memory window
                DX = window address in video memory (in granularity units)
            01h get video memory window
                Return: DX = window address in video memory (in gran. units)
        BL = window number
            00h window A
            01h window B
Return: AL = 4Fh function supported
        AH = status
            00h successful
            01h failed
SeeAlso: AX=4F06h,AX=4F07h,AX=7000h/BX=0004h