1.\" Copyright (c) 1985, 1991, 1993 2.\" The Regents of the University of California. 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.\" @(#)dhu.4 8.1 (Berkeley) 6/5/93 33.\" 34.Dd June 5, 1993 35.Dt DHU 4 vax 36.Os BSD 4.3 37.Sh NAME 38.Nm dhu 39.Nd 40.Tn DHU-11 41communications multiplexer 42.Sh SYNOPSIS 43.Cd "device dhu0 at uba0 csr 0160440 vector dhurint dhuxint" 44.Sh DESCRIPTION 45A 46.Tn DHU-11 47provides 16 communication lines. 48.Pp 49An optional argument 50.Ar flags 51may be supplied with the device specification 52in the config file indicating 53that the line corresponding to 54bit number 55.Ar i 56is not properly 57connected, and should be treated as hard-wired with carrier 58always present. Thus specifying 59.Ql flags 0x0004 60for 61.Li dhu0 62would cause line 63.Pa ttyS2 64to be treated in this way. 65.Pp 66Normal I/O 67control parameters for individual lines are managed by 68.Xr ioctl 2 69calls. 70Individual 71.Tn DHU-11 72lines may be configured to run at any of 13 speeds 73(50, 200 and 38400 baud are not available); 74the speed may be set via 75.Xr getty 8 76or 77.Xr stty 1 78or may be communicated by other programs which 79utilize 80.Xr ioctl 81such as 82.Xr ifcongif 8 , 83see 84.Xr tty 4 . 85.Pp 86The 87.Tn DHU-11 88driver normally uses input silos 89and delays receiver interrupts by 20 milliseconds 90rather than taking an interrupt on each input character. 91.Sh FILES 92.Bl -tag -width /dev/tty[S-Z][0-9a-f]xx -compact 93.It Pa /dev/tty[S-Z][0-9a-f] 94.El 95.Sh DIAGNOSTICS 96.Bl -diag 97.It dhu(%d,%d): NXM fault. 98No response from 99.Tn UNIBUS 100on a 101.Tn DMA 102transfer 103within a timeout period. This is often followed by a 104.Tn UNIBUS 105adapter 106error. This occurs most frequently when the 107.Tn UNIBUS 108is heavily loaded 109and when devices which hog the bus (such as 110.Tn RK07 Ns s ) 111are present. 112It is not serious. 113.Pp 114.It dhu%d: silo overflow. 115The character input silo overflowed 116before it could be serviced. This can happen if a hard error occurs 117when the 118.Tn CPU 119is running with elevated priority, as the system may 120then print a message on the console with interrupts disabled. 121.El 122.Sh NOTES 123The driver currently does not make full use of the hardware 124capabilities of the 125.Tn DHU-11 , 126for dealing with 127.Tn XON/XOFF 128flow-control or hard-wired 129lines for example. 130.Pp 131Although the devices are not the same, a 132.Tn DHU-11 133can convince the 134.Tn DH-11 135autoconfiguration code that it is a 136.Tn DH-11 . 137.Pp 138The 4 40-way cables are a pain. 139.Sh SEE ALSO 140.Xr tty 4 141.Sh HISTORY 142The 143.Nm 144driver appeared in 145.Bx 4.3 . 146