INT 13 - FAST! - API
        AH = 80h
        CX = 6572h
        DX = 1970h
        ES:BX -> data structure (see below)
        AL = function
            01h ???
            04h ???
            05h ???
            06h installation check
                Return: AX = 1965h if installed
            07h ???
            09h ???
            0Ah ???
            0Bh ???
            0Ch set ??? flag
            0Dh clear ??? flag
Return: AH = 00h if successful (except function 06h)

Format of data structure:
Offset  Size    Description
 00h    DWORD   pointer to 19-byte signature string
                13h 07h 06h 08h 11h 18h 0Fh 0Eh 02h 18h 13h 08h 0Bh 08h 01h 00h
                  04h 08h 15h  (v4.04)
 04h    ???     ???