INT 21 - DOS 3.1+ network - GET REDIRECTION MODE
        AX = 5F00h
        BL = redirection type
            03h printer
            04h disk drive
Return: CF set on error
            AX = error code (see AH=59h)
        CF clear if successful
            BH = redirection state
                00h off
                01h on
Note:   calls INT 2F/AX=111Eh with AX on top of the stack
SeeAlso: INT 2F/AX=111Eh