1.\" Copyright (c) 1985, 1991 Regents of the University of California. 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" from: @(#)dhu.4 6.3 (Berkeley) 3/27/91 33.\" $Id: dhu.4,v 1.2 1993/08/01 07:36:30 mycroft Exp $ 34.\" 35.Dd March 27, 1991 36.Dt DHU 4 vax 37.Os BSD 4.3 38.Sh NAME 39.Nm dhu 40.Nd 41.Tn DHU-11 42communications multiplexer 43.Sh SYNOPSIS 44.Cd "device dhu0 at uba0 csr 0160440 vector dhurint dhuxint" 45.Sh DESCRIPTION 46A 47.Tn DHU-11 48provides 16 communication lines. 49.Pp 50An optional argument 51.Ar flags 52may be supplied with the device specification 53in the config file indicating 54that the line corresponding to 55bit number 56.Ar i 57is not properly 58connected, and should be treated as hard-wired with carrier 59always present. Thus specifying 60.Ql flags 0x0004 61for 62.Li dhu0 63would cause line 64.Pa ttyS2 65to be treated in this way. 66.Pp 67Normal I/O 68control parameters for individual lines are managed by 69.Xr ioctl 2 70calls. 71Individual 72.Tn DHU-11 73lines may be configured to run at any of 13 speeds 74(50, 200 and 38400 baud are not available); 75the speed may be set via 76.Xr getty 8 77or 78.Xr stty 1 79or may be communicated by other programs which 80utilize 81.Xr ioctl 82such as 83.Xr ifcongif 8 , 84see 85.Xr tty 4 . 86.Pp 87The 88.Tn DHU-11 89driver normally uses input silos 90and delays receiver interrupts by 20 milliseconds 91rather than taking an interrupt on each input character. 92.Sh FILES 93.Bl -tag -width /dev/tty[S-Z][0-9a-f]xx -compact 94.It Pa /dev/tty[S-Z][0-9a-f] 95.El 96.Sh DIAGNOSTICS 97.Bl -diag 98.It dhu(%d,%d): NXM fault. 99No response from 100.Tn UNIBUS 101on a 102.Tn DMA 103transfer 104within a timeout period. This is often followed by a 105.Tn UNIBUS 106adapter 107error. This occurs most frequently when the 108.Tn UNIBUS 109is heavily loaded 110and when devices which hog the bus (such as 111.Tn RK07 Ns s ) 112are present. 113It is not serious. 114.Pp 115.It dhu%d: silo overflow. 116The character input silo overflowed 117before it could be serviced. This can happen if a hard error occurs 118when the 119.Tn CPU 120is running with elevated priority, as the system may 121then print a message on the console with interrupts disabled. 122.El 123.Sh NOTES 124The driver currently does not make full use of the hardware 125capabilities of the 126.Tn DHU-11 , 127for dealing with 128.Tn XON/XOFF 129flow-control or hard-wired 130lines for example. 131.Pp 132Although the devices are not the same, a 133.Tn DHU-11 134can convince the 135.Tn DH-11 136autoconfiguration code that it is a 137.Tn DH-11 . 138.Pp 139The 4 40-way cables are a pain. 140.Sh SEE ALSO 141.Xr tty 4 142.Sh HISTORY 143The 144.Nm 145driver appeared in 146.Bx 4.3 . 147