INT 67 - LIM EMS 4.0 - GET HANDLE DIRECTORY
        AH = 54h
        AL = subfunction
            00h get handle directory
               ES:DI -> buffer for handle directory (see below)
            01h search for named handle
               DS:SI -> 8-byte name
            02h get total number of handles
Return: AL = number of entries in handle directory (subfunction 00h)
        DX = value of named handle (subfunction 01h)
        BX = total number of handles (subfunction 02h)
        AH = status
            00h successful
            80h internal error
            81h hardware malfunction
            84h undefined function requested
            8Fh undefined subfunction
            A0h no such handle name
            A1h a handle found had no name

Format of handle directory entry:
Offset  Size    Description
 00h    WORD    handle
 02h  8 BYTEs   handle's name