104 lines
3.3 KiB
Groff
104 lines
3.3 KiB
Groff
.\" $NetBSD: ioasic.4,v 1.4 2004/05/11 22:42:47 wiz Exp $
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.\"
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.\" Copyright (c) 1996, 1997 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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.\" 4. 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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.Dd September 12, 1996
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.Dt IOASIC 4
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.Os
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.Sh NAME
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.Nm ioasic
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.Nd
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baseboard IO control ASIC for DEC TURBOchannel systems
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.Sh SYNOPSIS
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.Cd "ioasic0 at tc? slot ? offset ?"
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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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all DEC TURBOchannel machines with MIPS (DECstation 5000 series,
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excluding the 5000/200) and Alpha (3000-series) processors. On these
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machines (including the 5000/200), all baseboard devices should be
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configured as children of the
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.Nm
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device.
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.Pp
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The
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.Nm
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provides hardware DMA channels and interrupt support for several
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baseboard devices, including one
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.Nm asc
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SCSI device with a scatter/gather DMA channel, an mc146818-compatible
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.Nm mcclock ,
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an Am7930 audio device
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.Nm bba ,
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one or two
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.Nm scc
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two-port serial devices, and a AMD 7990 LANCE
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.Nm le
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Ethernet interface.
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.Pp
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The
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.Nm
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is also used for the floppy-disc drive and audio/ISDN hardware on
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the Personal DECstation and audio-equipped TURBOchannel Alphas,
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where the
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.Nm
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hardware provides a scatter-gather DMA channel between the 16-bit
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device and the 32-bit
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.Nm tc
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DMA address space.
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.Pp
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Support for scatter-gather DMA eliminates the need for additional 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 asc 4 ,
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.Xr bba 4 ,
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.Xr intro 4 ,
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.Xr le 4 ,
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.Xr mcclock 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 DECstation boot-time configuration code in
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.Bx 4.4 .
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.Sh BUGS
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The DECstation 5000/200 does not actually have an IOASIC
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chip, but for consistency it must be configured as if it did.
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