dfa(4)									dfa(4)

Name
       dfa - DFA01 communications interface

Syntax
       device dz0 at uba0 csr 0160100 flags 0x0 vector dzrint dzxint

Description
       The  DFA01 contains two DF224-compatible modems with a DZQ11-compatible
       interface.  Each line attached to the DFA01 behaves as described in See
       for  the	 encoding.  Lines may operate at 300, 1200, or 2400 baud.  The
       DZQ11 interface is capable of baud rates up to 9600 baud, but,  because
       the  modem  is  restricted  to  speeds of 300, 1200, and 2400 baud, all
       other baud rates are considered illegal and pass meaningless data.

       A flags field of 0x0 must be specified to indicate that the  lines  are
       to be treated as modems.

       An  entry  of  dfa01  should be used to describe the 2400 baud autodial
       attributes used by such programs as and For pulse tone dialing at  2400
       baud,  an  entry	 of dfa01-p should be used.  To dial at 1200 baud, the
       dfa01-1200 or dfa01-1200p (pulse dial) should  be  used.	  To  use  the
       DFA01 autodialer, the terminal line must be set to no parity.

       Any  entry in the file that specifies an ACU type of dfa01 must specify
       no parity.  The following example shows how a correct entry in the file
       may look:
       dial2400|2400 Baud attributes:\
	    :dv=/dev/ttyd0:br#2400:at=dfa01:du:pa=none:

       The  driver  normally  uses its input silos and polls for input at each
       clock tick (10 milliseconds) rather than taking an  interrupt  on  each
       input character.

       will  produce  four terminal lines for the DZQ11 interface.  The second
       and fourth lines are the actual modem lines.  The first and third lines
       pass status information when the modem is on line.

Diagnostics
       dz%d: receive fifo overflow.
       The  character input fifo overflowed before it could be serviced.  This
       can happen if other devices heavily utilize the bus and CPU, preventing
       interrupts  from	 the  DFA01 from being serviced.  This may cause a few
       input characters to be lost to users.  It is not serious.

Files
       Dialups

See Also
       tty(4), acucap(5), MAKEDEV(8)

				      VAX				dfa(4)

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