Function 5F03h          Make Network Connection                      DOS 3.1+

    Creates a connection to a network device or drive, or redirects a
    local device or drive if a local name is specified.

        Entry   AX   = 5F03h
                BL    = Device type (local)
                        | 3 = printer
                        | 4 = drive
                CX    = User value to save (0)
                DS:SI = Pointer to ASCIIZ local device name
                        (max. 16 bytes)
                ES:DI = Pointer to ASCIIZ network name followed
                        by ASCIIZ password (max. 128 bytes total)

        Return  Nothing
                or
                AX = Error code, if CF is set
                     | 01h Invalid function (Network not running)
                     | 03h Path not found
                     | 05h Access denied (Bad password/device)
                     | 08h Insufficient memory
                     | 0Fh Invalid drive
                     | 12h No more files
                     | 57h Invalid parameter

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    This function allows a program to redirect I/O from a local
    printer or disk drive to a network device. The program can also
    control access to the network device by means of a password.

    The parameter passed in CX specifies a value to be saved and
    returned to a program that calls function 5F02h (Get Assign-List
    Entry).
    If the Device Type is 03h, the local device is a printer, and
    the local device name must be PRN, LPT1, LPT2, or LPT3.
    If the Device Type is 04h, the local device is a disk drive and
    the string at DS:SI must specify either a drive letter followed by
    a colon or a null string. If a drive letter is specified, DOS
    redirects the drive to the network device. If a null string is
    specified, DOS attempts to provide access to the network device
    without redirecting a local disk drive.

    If the network device has no password, the second string at ES:DI
    must be a null string.