1.\" $NetBSD: ast.4,v 1.10 2001/09/11 17:39:01 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. All advertising materials mentioning features or use of this software 18.\" must display the following acknowledgement: 19.\" This product includes software developed by the University of 20.\" California, Berkeley and its contributors. 21.\" 4. Neither the name of the University nor the names of its contributors 22.\" may be used to endorse or promote products derived from this software 23.\" without specific prior written permission. 24.\" 25.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35.\" SUCH DAMAGE. 36.\" 37.\" from: @(#)dca.4 5.2 (Berkeley) 3/27/91 38.\" from: Id: com.4,v 1.1 1993/08/06 11:19:07 cgd Exp 39.\" 40.Dd March 30, 1994 41.Dt AST 4 42.Os 43.Sh NAME 44.Nm ast 45.Nd 46multiplexing serial communications interface 47.Sh SYNOPSIS 48.Cd "ast0 at isa? port 0x1a0 irq 5" 49.Cd "com2 at ast? slave ?" 50.Cd "com3 at ast? slave ?" 51.Cd "com4 at ast? slave ?" 52.Cd "com5 at ast? slave ?" 53.Sh DESCRIPTION 54The 55.Nm ast 56driver provides support for boards that multiplex together up to four 57.Tn EIA 58.Tn RS-232C 59.Pf ( Tn CCITT 60.Tn V.28 ) 61communications interfaces. Apparently the original master of hardware 62using this multiplexing protocol was AST. 63.Pp 64Each 65.Nm 66device is the master device for up to four 67.Nm com 68devices. The kernel configuration specifies these 69.Nm com 70devices as slave devices of the 71.Nm 72device, as shown in the synopsis. The slave ID given for each 73.Nm com 74device determines which bit in the interrupt multiplexing register is 75tested to find interrupts for that device. 76The 77.Tn port 78specification for the 79.Nm 80device is used to compute the base addresses for the 81.Nm com 82subdevices and the port for the interrupt multiplexing register. 83.Sh FILES 84.Bl -tag -width Pa 85.It Pa /dev/tty0? 86.El 87.Sh SEE ALSO 88.Xr com 4 89.Sh HISTORY 90The 91.Nm 92driver was written by Roland McGrath and placed into the public 93domain. 94