93 lines
3.0 KiB
Groff
93 lines
3.0 KiB
Groff
.\" $NetBSD: ast.4,v 1.12 2004/05/11 22:42:47 wiz Exp $
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.\"
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.\" 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. 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: Id: com.4,v 1.1 1993/08/06 11:19:07 cgd Exp
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.\"
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.Dd March 30, 1994
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.Dt AST 4
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.Os
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.Sh NAME
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.Nm ast
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.Nd
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multiplexing serial communications interface
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.Sh SYNOPSIS
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.Cd "ast0 at isa? port 0x1a0 irq 5"
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.Cd "com2 at ast? slave ?"
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.Cd "com3 at ast? slave ?"
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.Cd "com4 at ast? slave ?"
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.Cd "com5 at ast? slave ?"
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.Sh DESCRIPTION
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The
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.Nm ast
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driver provides support for boards that multiplex together up to four
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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.
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Apparently the original maker of hardware
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using this multiplexing protocol was AST.
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.Pp
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Each
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.Nm
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device is the master device for up to four
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.Nm com
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devices.
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The kernel configuration specifies these
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.Nm com
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devices as slave devices of the
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.Nm
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device, as shown in the synopsis.
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The slave ID given for each
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.Nm com
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device determines which bit in the interrupt multiplexing register is
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tested to find interrupts for that device.
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The
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.Tn port
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specification for the
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.Nm
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device is used to compute the base addresses for the
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.Nm com
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subdevices and the port for the interrupt multiplexing register.
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.Sh FILES
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.Bl -tag -width Pa
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.It Pa /dev/tty0?
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.El
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.Sh SEE ALSO
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.Xr com 4
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.Sh HISTORY
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The
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.Nm
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driver was written by Roland McGrath and placed into the public
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domain.
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