INT 60 - MDEBUG - GET ADDRESS OF THE HELP REGISTERS
        AH = 01h
        DS:SI -> password or a null byte
Return: AX = return code
            FFFEh password is invalid
            FFFDh display mode is invalid
           else successful
                ES:DI point to the help registers of MDEBUG
               ES:DI-02h  -> R0 (WORD)
               ES:DI      -> R1 (WORD)
               ES:DI+02h  -> R2 (WORD)
               ES:DI+04h  -> R3 (WORD)
               ...
               ES:DI+0Eh  -> R8 (WORD)