103 lines
3.7 KiB
Groff
103 lines
3.7 KiB
Groff
.\" Copyright (c) 1990, 1991 The Regents of the University of California.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" the Systems Programming Group of the University of Utah Computer
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.\" Science Department.
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" from: @(#)dca.4 5.2 (Berkeley) 3/27/91
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.\" from: com.4,v 1.1 1993/08/06 11:19:07 cgd Exp
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.\" $Id$
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.\"
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.Dd August 28, 1993
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.Dt COM 4 i386
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.Os FreeBSD
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.Sh NAME
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.Nm com
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.Nd
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serial communications interface
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.Sh SYNOPSIS
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.Cd "device com0 at isa? port" \&"IO_COM1\&" tty irq 4 vector comintr
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.Cd "device com1 at isa? port" \&"IO_COM2\&" tty irq 3 vector comintr
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.Cd "device com2 at isa? port" \&"IO_COM3\&" tty irq 5 vector comintr
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.Cd "device com3 at isa? port" \&"IO_COM4\&" tty irq 9 vector comintr
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.Sh DESCRIPTION
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The
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.Nm com
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driver provides support for NS8250-, NS16450-, and NS16550-based
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.Tn EIA
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.Tn RS-232C
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.Pf ( Tn CCITT
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.Tn V.28 )
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communications interfaces. The NS8250 and NS16450 have single character
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buffers, and the NS16550 has a 16 character buffer.
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.Pp
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Input and output for each line may set to one of following baud rates;
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50, 75, 110, 134.5, 150, 300, 600, 1200, 1800, 2400, 4800, 9600,
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19200, 38400, 57600, or 115200.
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.Sh FILES
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.Bl -tag -width Pa
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.It Pa /dev/tty00
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.It Pa /dev/tty01
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.El
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.Sh DIAGNOSTICS
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.Bl -diag
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.It com%d: silo overflow.
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The single-character input
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.Dq silo
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has overflowed and incoming data has been lost.
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.\".It com%d: weird interrupt: %x.
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.\"The device has generated an unexpected interrupt
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.\"with the code listed.
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.El
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.Sh SEE ALSO
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.Xr tty 4
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.Xr sio 4
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.Sh HISTORY
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The
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.Nm
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driver is derived from the
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.Nm HP9000/300
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.Nm dca
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driver and is
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.Ud
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.Sh BUGS
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Data loss is possible on busy systems with baud rates greater than 300.
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The
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.Nm com
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driver is slow, buggy, and not properly tested.
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.Pp
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The name of this driver and the constants which define the locations
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of the various seiral ports are holdovers from
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.Nm DOS .
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.Pp
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As usual, you get what you pay for; cheap NS16550 clones
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generally don't work.
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