1.\" $NetBSD: ioasic.4,v 1.3 2001/10/29 18:59:55 gmcgarry Exp $ 2.\" 3.\" Copyright (c) 1996, 1997 Jonathan Stone. 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed by Jonathan Stone. 17.\" 4. The name of the author may not be used to endorse or promote products 18.\" derived from this software without specific prior written permission 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 21.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 22.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 23.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 24.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 25.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 29.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30.\" 31.Dd September 12, 1996 32.Dt IOASIC 4 33.Os 34.Sh NAME 35.Nm ioasic 36.Nd 37baseboard IO control ASIC for DEC TURBOchannel systems 38.Sh SYNOPSIS 39.Cd "ioasic0 at tc? slot ? offset ?" 40.Sh DESCRIPTION 41The 42.Nm 43driver provides support for the DEC proprietary IOCTL ASIC found on 44all DEC TURBOchannel machines with MIPS (DECstation 5000 series, 45excluding the 5000/200) and Alpha (3000-series) processors. On these 46machines (including the 5000/200), all baseboard devices should be 47configured as children of the 48.Nm 49device. 50.Pp 51The 52.Nm 53provides hardware DMA channels and interrupt support for several 54baseboard devices, including one 55.Nm asc 56SCSI device with a scatter/gather DMA channel, an mc146818-compatible 57.Nm mcclock , 58an Am9730 audio device 59.Nm bba , 60one or two 61.Nm scc 62two-port serial devices, and a AMD 9770 LANCE 63.Nm le 64Ethernet interface. 65.Pp 66The 67.Nm 68is also used for the floppy-disc drive and audio/ISDN hardware on 69the Personal DECstation and audio-equipped TURBOchannel Alphas, 70where the 71.Nm 72hardware provides a scatter-gather DMA channel between the 16-bit 73device and the 32-bit 74.Nm tc 75DMA address space. 76.Pp 77Support for scatter-gather DMA eliminates the need for additional copying. 78A baseboard 79.Nm asc 80SCSI adaptor attached to an 81.Nm ioasic 82will give slightly better performance than its 83.Nm tc 84counterpart. 85.Sh SEE ALSO 86.Xr asc 4 , 87.Xr bba 4 , 88.Xr intro 4 , 89.Xr le 4 , 90.Xr mcclock 4 , 91.Xr scc 4 , 92.Xr tc 4 93.Sh HISTORY 94The 95.Nm 96driver 97first appeared in 98.Nx 1.1 , 99derived from DECstation boot-time configuration code in 100.Bx 4.4 . 101.Sh BUGS 102The DECstation 5000/200 does not actually have an IOASIC 103chip, but for consistency it must be configured as if it did. 104