.\" $NetBSD: dh.4,v 1.17 2017/08/01 11:11:17 wiz Exp $ .\" .\" Copyright (c) 1980, 1991, 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" from: @(#)dh.4 8.1 (Berkeley) 6/5/93 .\" .Dd June 5, 1993 .Dt DH 4 vax .Os .Sh NAME .Nm dh .Nd .Tn DH-11 Ns / Ns Tn DM-11 serial multiplexer device interface .Sh SYNOPSIS .Cd "dh0 at uba0 csr 0160020 vector dhrint dhxint" Op Ar flags .Cd "dm0 at uba0 csr 0170500 vector dmintr" Op Ar flags .Sh DESCRIPTION NOTE: This driver has not been ported from .Bx 4.4 yet. .Pp A .Tn DH-11 provides 16 serial communication lines; .Tn DM-11 Ns s may optionally be paired with .Tn DH-11 Ns s to provide modem control for the lines. .Pp An optional argument .Ar flags may be supplied with the device specification in the .Xr config 1 file indicating that the line corresponding to bit number .Ar i is not properly connected, and should be treated as hard-wired with carrier always present. Thus specifying .Ql flags 0x0004 for .Li dh0 would cause line .Pa ttyh2 to be treated in this way. .Pp Normal I/O control parameters for individual lines are managed by .Xr ioctl 2 calls. Line speeds may be initiated via .Xr getty 8 and .Xr stty 1 or may be communicated by other programs which use .Xr ioctl 2 such as .Xr ifconfig 8 , see .Xr tty 4 . .Pp The .Nm dh driver monitors the rate of input on each board, and switches between the use of character-at-a-time interrupts and input silos. While the silo is enabled during periods of high-speed input, the driver polls for input 30 times per second. .Sh FILES .Bl -tag -width /dev/tty[h-o][0-9a-f]x -compact .It Pa /dev/tty[h-o][0-9a-f] .It Pa /dev/ttyd[0-9a-f] .El .Sh DIAGNOSTICS .Bl -diag .It dh%d: NXM. No response from .Tn UNIBUS on a DMA transfer within a timeout period. This is often followed by a .Tn UNIBUS adapter error. This occurs most frequently when the .Tn UNIBUS is heavily loaded and when devices which hog the bus (such as .Tn RK07 Ns s ) are present. It is not serious. .It dh%d: silo overflow. The character input silo overflowed before it could be serviced. This can happen if a hard error occurs when the .Tn CPU is running with elevated priority, as the system will then print a message on the console with interrupts disabled. It is not serious. .El .Sh SEE ALSO .Xr tty 4 .Sh HISTORY A .Nm driver appeared in .At v6 .