1.\" 2.\" Copyright (c) 1990, 1991 The Regents of the University of California. 3.\" All rights reserved. 4.\" 5.\" This code is derived from software contributed to Berkeley by 6.\" the Systems Programming Group of the University of Utah Computer 7.\" Science Department. 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. All advertising materials mentioning features or use of this software 17.\" must display the following acknowledgement: 18.\" This product includes software developed by the University of 19.\" California, Berkeley and its contributors. 20.\" 4. Neither the name of the University nor the names of its contributors 21.\" may be used to endorse or promote products derived from this software 22.\" without specific prior written permission. 23.\" 24.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34.\" SUCH DAMAGE. 35.\" 36.\" from: @(#)dca.4 5.2 (Berkeley) 3/27/91 37.\" from: Id: com.4,v 1.1 1993/08/06 11:19:07 cgd Exp 38.\" $Id: ast.4,v 1.2 1994/03/31 06:50:08 mycroft Exp $ 39.\" 40.Dd March 30, 1994 41.Dt AST 4 i386 42.Os NetBSD 0.9a 43.Sh NAME 44.Nm ast 45.Nd 46multiplexing serial communications interface 47.Sh SYNOPSIS 48.Cd "master ast0 at isa? port 0x1a0 tty irq 5 vector astintr" 49.Cd "device com2 at ast0 slave 0 flags 1" 50.Cd "device com3 at ast0 slave 1 flags 1" 51.Cd "device com4 at ast0 slave 2 flags 1" 52.Cd "device com5 at ast0 slave 3 flags 1" 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 kernel configuration specification for each slave 77.Nm com 78device can optionally omit the 79.Tn port 80specification, in which case the slaves are assumed to be at 81sequential addresses. The 82.Tn port 83specification for the 84.Nm 85device is used to compute the port for the interrupt multiplexing 86register, and taken as the default port for the first slave 87.Nm com 88device. 89.Sh FILES 90.Bl -tag -width Pa 91.It Pa /dev/tty0? 92.El 93.Sh SEE ALSO 94.Xr com 4 95.Sh HISTORY 96The 97.Nm 98driver was written by Roland McGrath and placed into the public 99domain. It was inspired by the work of Bill Sommerfeld on support for 100this hardware in the 101.Nm com 102driver. 103 104