440Ch                   ■ Generic IOCTL for Character Devices

    Int 21h, function 440Ch subfunctions:

        Minor code      Subfunction
            45h         Set Iteration Count
            4ah         Select Code Page
            4ch         Start Code-Page Prepare
            4dh         End Code-Page Prepare
            5fh         Set Display Mode
            65h         Get Iteration Count
            6ah         Query Selected Code Page
            6bh         Query Code-Page Prepare List
            7fh         Get Display Mode