INT 2F - MDEBUG command driver - GET ADDRESS OF THE OLD INT 2F
        AX = D110h
Return: DL = FFh
        ES:BX -> next program in the chain for INT 2F
        CX = code segment of this driver
        DI = offset of driver identification table (see below) (v1.60+)
Notes:  only called by the transient part of the driver
        must be reentrant and the driver must not chain this function to the
          old INT 2F

Format of the driver identification table:
Offset  Size    Description
 00h  26 BYTEs   signature "Kommandotreiber f.r MDEBUG"
                                             - Note: ASCII 129,German U-umlaut
 27h  12 BYTEs   name of driver, e.g. "MDHISDRV.COM"
                 each driver must have a unique name