147 lines
4.1 KiB
Groff
147 lines
4.1 KiB
Groff
.\" Copyright (c) 1985, 1991 Regents of the University of California.
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.\" All rights reserved.
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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: @(#)dhu.4 6.3 (Berkeley) 3/27/91
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.\" $Id: dhu.4,v 1.2 1993/08/01 07:36:30 mycroft Exp $
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.\"
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.Dd March 27, 1991
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.Dt DHU 4 vax
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.Os BSD 4.3
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.Sh NAME
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.Nm dhu
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.Nd
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.Tn DHU-11
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communications multiplexer
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.Sh SYNOPSIS
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.Cd "device dhu0 at uba0 csr 0160440 vector dhurint dhuxint"
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.Sh DESCRIPTION
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A
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.Tn DHU-11
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provides 16 communication lines.
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.Pp
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An optional argument
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.Ar flags
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may be supplied with the device specification
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in the config file indicating
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that the line corresponding to
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bit number
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.Ar i
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is not properly
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connected, and should be treated as hard-wired with carrier
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always present. Thus specifying
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.Ql flags 0x0004
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for
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.Li dhu0
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would cause line
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.Pa ttyS2
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to be treated in this way.
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.Pp
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Normal I/O
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control parameters for individual lines are managed by
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.Xr ioctl 2
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calls.
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Individual
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.Tn DHU-11
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lines may be configured to run at any of 13 speeds
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(50, 200 and 38400 baud are not available);
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the speed may be set via
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.Xr getty 8
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or
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.Xr stty 1
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or may be communicated by other programs which
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utilize
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.Xr ioctl
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such as
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.Xr ifcongif 8 ,
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see
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.Xr tty 4 .
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.Pp
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The
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.Tn DHU-11
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driver normally uses input silos
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and delays receiver interrupts by 20 milliseconds
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rather than taking an interrupt on each input character.
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.Sh FILES
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.Bl -tag -width /dev/tty[S-Z][0-9a-f]xx -compact
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.It Pa /dev/tty[S-Z][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 dhu(%d,%d): NXM fault.
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No response from
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.Tn UNIBUS
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on a
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.Tn DMA
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transfer
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within a timeout period. This is often followed by a
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.Tn UNIBUS
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adapter
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error. This occurs most frequently when the
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.Tn UNIBUS
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is heavily loaded
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and when devices which hog the bus (such as
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.Tn RK07 Ns s )
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are present.
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It is not serious.
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.Pp
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.It dhu%d: silo overflow.
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The character input silo overflowed
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before it could be serviced. This can happen if a hard error occurs
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when the
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.Tn CPU
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is running with elevated priority, as the system may
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then print a message on the console with interrupts disabled.
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.El
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.Sh NOTES
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The driver currently does not make full use of the hardware
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capabilities of the
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.Tn DHU-11 ,
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for dealing with
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.Tn XON/XOFF
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flow-control or hard-wired
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lines for example.
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.Pp
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Although the devices are not the same, a
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.Tn DHU-11
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can convince the
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.Tn DH-11
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autoconfiguration code that it is a
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.Tn DH-11 .
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.Pp
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The 4 40-way cables are a pain.
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.Sh SEE ALSO
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.Xr tty 4
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.Sh HISTORY
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The
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.Nm
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driver appeared in
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.Bx 4.3 .
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