102 lines
3.6 KiB
Groff
102 lines
3.6 KiB
Groff
.\" $NetBSD: dcm.4,v 1.7 2001/09/11 06:30:03 gmcgarry Exp $
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.\"
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.\" Copyright (c) 1990, 1991, 1993
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.\" The Regents of the University of California. 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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.\"
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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: @(#)dcm.4 8.1 (Berkeley) 6/9/93
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.\"
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.Dd June 9, 1993
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.Dt DCM 4 hp300
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.Os
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.Sh NAME
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.Nm dcm
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.Nd
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.Tn HP98642A
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serial communications multiplexer
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.Sh SYNOPSIS
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.Cd "dcm* at dio? scode ? flags 0xe"
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.Sh DESCRIPTION
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The
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.Tn 98642A
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is a four port
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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
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multiplexer. The
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.Tn 98642A
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has three direct-connect ports and one port with
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full modem control.
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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,
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9600, 19200, 38400.
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.Pp
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.Ar Flags
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is usually specified as 0xe since 3 of the 4 ports (1-3) do not support
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modem control and should be treated as hard-wired with carrier always present.
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If port 0 does not have the need for modem control then flags can be specified
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as
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.Ql 0xf .
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.Pp
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Each port on the
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.Tn 98642A
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has a 128 byte input silo and a 16 byte output silo.
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Interrupts happen on a per character basis unless the interrupt
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rate for the card reaches 70 interrupts per second at which time the
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driver changes to a 16.7ms (60 interrupts per second) polling scheme until
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the interrupt rate drops.
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.Sh FILES
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.Bl -tag -width /dev/tty0[0-9a-f] -compact
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.It Pa /dev/tty0[0-9a-f]
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.El
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.Sh DIAGNOSTICS
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.Bl -diag
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.It dcm%d port%d: silo overflow
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Input Silo has overflowed and incoming data
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has been lost.
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.Pp
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.It dcm%d port%d: uart overflow
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The 3 character buffer in the uart has
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overflowed.
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.El
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.Sh SEE ALSO
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.Xr dio 4 ,
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.Xr tty 4
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.Sh BUGS
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Total throughput per card, all ports together, is limited to 76800 bits per
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second continuous input rate.
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