asyc(7)                                                      asyc(7)


       NAME
             asyc, asyhp - asynchronous and high performance asynchronous
             serial ports

       DESCRIPTION
             The asyc driver supports both the system board serial port and
             an additional serial adapter simultaneously.  While up to four
             serial ports are supported, the system default enables two
             serial ports.  If an adapter for a port is not installed, an
             attempt to open it will fail.  Depending on your system
             processor type and UART, the port can be programmed for speed
             (50-38400 baud), character length, and parity.  Output speed
             is always the same as input speed.  The port behaves as
             described in termio(7).

             The asynchronous port is a character-at-a-time device for both
             input and output.  This characteristic both limits the
             bandwidth that can be achieved over a line, and increases the
             interrupt loading on the central processor.  File transfer
             programs such as uucp(1C) may be able to function well at
             speeds greater than 9600 baud, depending on your system
             processor type and UART.

             The baud rates of the serial adapter programmable baud-rate
             generator do not correspond exactly with system baud rates.
             Specifically, setting B0 will cause a disconnect, setting EXTA
             will set 19200 baud, and setting EXTB will set 38400 baud.  It
             is not possible to directly set 2000, 3600, or 7200 baud.  The
             asynchronous ports driver supports interrupt sharing, as well
             as line signal (hardware) flow control when the device node
             /dev/tty0?h is used.  The /dev/tty0?s ports are software flow
             control nodes as are the /dev/tty0? nodes.

       USAGE
             The system is delivered with 16450 UART equivalents for the
             two COM ports, COM1 and COM2.  You can add COM3 and COM4 as
             high performance asynchronous ports by mixing 16450 UARTs and
             16550 UARTs on your machine.

             Add the two ports to your system by following these steps:

             1     Create two additional device nodes by adding the lines
                         iasy tty02    c    4
                         iasy tty03    c    6




                           Copyright 1994 Novell, Inc.               Page 1

      asyc(7)                                                      asyc(7)


                  to /etc/conf/node.d/iasy.

            2     You may want to activate asyc for all four ports, since
                  the asyc driver supports both 16450 and 16550 UARTs.
                  Use the /sbin/dcu command to enable the two new ports.
                  See dcu(1M).

            3     While /sbin/dcu does an idbuild, you need to reboot the
                  system for the additional ports to work.

         Files
            /dev/tty*
            /dev/term/*

      REFERENCES
            dcu(1M), Node(4), signal(2), termio(7)

      NOTICES
            The asyhp driver, which was previously described on this page,
            is obsolete; use asyc instead.




























                          Copyright 1994 Novell, Inc.               Page 2