1.\" $NetBSD: ast.4,v 1.12 2004/05/11 22:42:47 wiz Exp $ 2.\" 3.\" Copyright (c) 1990, 1991 The Regents of the University of California. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" the Systems Programming Group of the University of Utah Computer 8.\" Science Department. 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 3. Neither the name of the University nor the names of its contributors 18.\" may be used to endorse or promote products derived from this software 19.\" without specific prior written permission. 20.\" 21.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31.\" SUCH DAMAGE. 32.\" 33.\" from: @(#)dca.4 5.2 (Berkeley) 3/27/91 34.\" from: Id: com.4,v 1.1 1993/08/06 11:19:07 cgd Exp 35.\" 36.Dd March 30, 1994 37.Dt AST 4 38.Os 39.Sh NAME 40.Nm ast 41.Nd 42multiplexing serial communications interface 43.Sh SYNOPSIS 44.Cd "ast0 at isa? port 0x1a0 irq 5" 45.Cd "com2 at ast? slave ?" 46.Cd "com3 at ast? slave ?" 47.Cd "com4 at ast? slave ?" 48.Cd "com5 at ast? slave ?" 49.Sh DESCRIPTION 50The 51.Nm ast 52driver provides support for boards that multiplex together up to four 53.Tn EIA 54.Tn RS-232C 55.Pf ( Tn CCITT 56.Tn V.28 ) 57communications interfaces. 58Apparently the original maker of hardware 59using this multiplexing protocol was AST. 60.Pp 61Each 62.Nm 63device is the master device for up to four 64.Nm com 65devices. 66The kernel configuration specifies these 67.Nm com 68devices as slave devices of the 69.Nm 70device, as shown in the synopsis. 71The slave ID given for each 72.Nm com 73device determines which bit in the interrupt multiplexing register is 74tested to find interrupts for that device. 75The 76.Tn port 77specification for the 78.Nm 79device is used to compute the base addresses for the 80.Nm com 81subdevices and the port for the interrupt multiplexing register. 82.Sh FILES 83.Bl -tag -width Pa 84.It Pa /dev/tty0? 85.El 86.Sh SEE ALSO 87.Xr com 4 88.Sh HISTORY 89The 90.Nm 91driver was written by Roland McGrath and placed into the public 92domain. 93