99 lines
3.1 KiB
Groff
99 lines
3.1 KiB
Groff
.\"
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.\" Copyright (c) 1996 Jonathan Stone.
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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 Jonathan Stone.
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.\" 3. The name of the author may not be used to endorse or promote products
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.\" derived from this software without specific prior written permission
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $Id: ioasic.4,v 1.1 1996/08/11 02:29:06 jonathan Exp $
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.\"
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.Dd August 6, 1996
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.Dt IOASIC 4 pmax
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.Os NetBSD 1.2
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.Sh NAME
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.Nm ioasic
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.Nd
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turbochannel SCSI adaptor
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.Sh SYNOPSIS
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.Cd "ioasic? at mainbus"
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.Sh DESCRIPTION
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The
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.Nm
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driver provides support for the DEC proprietary IOCTL asic found on
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Decstation 5000 series machines (excluding the 5000/200), and on
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Turbochannel-based Alphas. On these machines (including the
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5000/200), all baseboard devices should be configured as children
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of the
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.Nm ioasic .
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The
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.nm
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provides hardware DMA channels and interrupt support for
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several baseboard devices, including one
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.Nm asc
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scsi device with a scatter/gather DMA channel, up to two
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.Nm scc
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devices, a
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.Nm tc
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turbochannel expansion bus with two, three, or six slots.
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.Pp
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The
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.Nm
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is also used for theose
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floppy-disc drive and audio/ISDN hardware
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on the Personal Decstation and Alpha.
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.Nm
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hardware is used to interface to
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a
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scatter-gather DMA channel.
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.Pp
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Support for scatter-gather DMA eliminates the need for copying.
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A baseboard
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.Nm asc
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SCSI adaptor attached to an
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.Nm ioasic
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will give slightly better performance than its
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.Nm tc
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counterpart.
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.Sh SEE ALSO
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.Xr intro 4 ,
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.Xr clock 4,
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.Xr asc 4 ,
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.Xr le 4 ,
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.Xr scc 4 ,
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.Xr tc 4 .
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.Sh HISTORY
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The
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.Nm
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driver
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first appeared in
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.Nx 1.1 ,
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derived from the
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.Sh BUGS
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The Decstation 5000/200 does not actually have an
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.Nm ioasic
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chip, but for consistency it must be configured as if it
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did.
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