1.\" Copyright (c) 1980, 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: @(#)dh.4 6.3 (Berkeley) 3/27/91 33.\" $Id: dh.4,v 1.2 1993/08/01 07:36:31 mycroft Exp $ 34.\" 35.Dd March 27, 1991 36.Dt DH 4 vax 37.Os BSD 4 38.Sh NAME 39.Nm dh 40.Nd 41.Tn DH-11 Ns / Tn DM-11 42multiplexer device interface 43.Sh SYNOPSIS 44.Cd "device dh0 at uba0 csr 0160020 vector dhrint dhxint" Op Ar flags 45.Cd "device dm0 at uba0 csr 0170500 vector dmintr" Op Ar flags 46.Sh DESCRIPTION 47A 48.Tn DH-11 49provides 16 serial communication lines; 50.Tn DM-11 Ns s 51may optionally be 52paired with 53.Tn DH-11 Ns s 54to provide modem control for the lines. 55.Pp 56An optional argument 57.Ar flags 58may be supplied with the device specification 59in the 60.Xr config 8 61file indicating 62that the line corresponding to 63bit number 64.Ar i 65is not properly 66connected, and should be treated as hard-wired with carrier 67always present. Thus specifying 68.Ql flags 0x0004 69for 70.Li dh0 71would cause line 72.Pa ttyh2 73to be treated in this way. 74.Pp 75Normal I/O 76control parameters for individual lines are managed by 77.Xr ioctl 2 78calls. 79Line speeds may be initiated via 80.Xr getty 8 81and 82.Xr stty 1 83or may be communicated by other programs which 84utilize 85.Xr ioctl 86such as 87.Xr ifcongif 8 , 88see 89.Xr tty 4 . 90.Pp 91The 92.Nm dh 93driver monitors the rate of input on each board, 94and switches between the use of character-at-a-time interrupts 95and input silos. 96While the silo is enabled during periods of high-speed input, 97the driver polls for input 30 times per second. 98.Sh FILES 99.Bl -tag -width /dev/tty[h-o][0-9a-f]x -compact 100.It Pa /dev/tty[h-o][0-9a-f] 101.It Pa /dev/ttyd[0-9a-f] 102.El 103.Sh DIAGNOSTICS 104.Bl -diag 105.It dh%d: NXM. 106No response from 107.Tn UNIBUS 108on a dma transfer 109within a timeout period. This is often followed by a 110.Tn UNIBUS 111adapter 112error. This occurs most frequently when the 113.Tn UNIBUS 114is heavily loaded 115and when devices which hog the bus (such as 116.Tn RK07 Ns s) are present. 117It is not serious. 118.Pp 119.It dh%d: silo overflow. 120The character input silo overflowed 121before it could be serviced. This can happen if a hard error occurs 122when the 123.Tn CPU 124is running with elevated priority, as the system will 125then print a message on the console with interrupts disabled. 126It is not serious. 127.El 128.Sh SEE ALSO 129.Xr tty 4 130.Sh HISTORY 131A 132.Nm 133driver appeared in 134.At v6 . 135