Function 5Bh            Create New File                              DOS 3.0+

    Creates the specified file, if the file does not already exist.

        Entry   AH    = 5Bh
                CX    = File attributes
                DS:DX = Pointer to ASCIIZ filename

        Return  AX = File handle
                or
                AX = Error code, if CF is set
                     | 03h Path not found
                     | 04h No handle available
                     | 05h Access denied
                     | 50h File exists

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    The filename parameter must be a valid DOS filename and cannot
    contain wildcards.
    The file attributes parameter can be a combination of:
    attr_normal, attr_readonly, attr_hidden, attr_system, attr_archive.


    This function will create a file and assign it the first available
    file handle. If the specified already exists, this function fails.

    When DOS creates a file, it opens it with read-and-write access
    and compatibility sharing mode and sets the file pointer to zero.
    If the attr_readonly attribute is specified, it takes affect only
    after the new file is closed.