INT 16 - BORLAND TURBO LIGHTNING - API
        AH = EDh
        BH = EDh
        BL = function
            00h installation check
                Return: AX = 5205h
                        CH = major version
                        CL = minor version
            01h ???
            02h get resident CS
                Return: AX = code segment of resident portion
            03h get resident ???
                Return: AX = offset of some buffer in resident code seg
            04h ???
            05h set ???
                AL = 0 to 0Ch
                Return: AX = status
                            0000h if OK
                            0001h if out of range.
            06h ???
            07h ???
            08h ???
                AL = char???
                CX = ???
                DX = ???
                Return: AX = 0, 1 or 2
            09h ???
            0Ah ???
                CX = ???
                DX = ???
                Return: AX = ???
            0Bh ???
                DS:SI -> ???
                Return: AX = 0, 40h, 80h
            0Ch ???
                DS:SI -> ???
                Return: AH = 0
                        AL = ???
            0Dh set ???
                (sets an internal flag)
            0Eh ???
                DS:SI -> ???
                Return: AX = 0, 1 or 2.
            0Fh ???
            10h ???
Notes:  AX in general returns an error code from most functions.