INT 21 - DOS 3.1+ network, Banyan VINES, LANtastic - REDIRECT DEVICE
        AX = 5F03h
        BL = device type
            03h printer
            04h disk drive
        CX = user data to save
                0000h for LANtastic
        DS:SI -> ASCIZ local device name (16 bytes max)
        ES:DI -> ASCIZ network name + ASCIZ password (128 bytes max total)
Return: CF clear if successful
        CF set on error
            AX = error code (01h,03h,05h,08h,0Fh,12h) (see AH=59h)
Notes:  if device type is disk drive, DS:SI must point at either a null string
          or a string consisting the drive letter followed by a colon; if a
          null string, the network attempts to access the destination without
          redirecting a local drive
        calls INT 2F/AX=111Eh with AX on top of the stack
SeeAlso: AX=5F04h,INT 2F/AX=111Eh