.\" Copyright (c) 1985, 1991 Regents of the University of California.
.\" %sccs.include.redist.man%
.\" @(#)dhu.4 6.3 (Berkeley) %G%
communications multiplexer
.Cd "device dhu0 at uba0 csr 0160440 vector dhurint dhuxint"
provides 16 communication lines.
may be supplied with the device specification
in the config file indicating
that the line corresponding to
connected, and should be treated as hard-wired with carrier
always present. Thus specifying
to be treated in this way.
control parameters for individual lines are managed by
lines may be configured to run at any of 13 speeds
(50, 200 and 38400 baud are not available);
or may be communicated by other programs which
driver normally uses input silos
and delays receiver interrupts by 20 milliseconds
rather than taking an interrupt on each input character.
.Bl -tag -width /dev/tty[S-Z][0-9a-f]xx -compact
.It Pa /dev/tty[S-Z][0-9a-f]
.It dhu(%d,%d): NXM fault.
within a timeout period. This is often followed by a
error. This occurs most frequently when the
and when devices which hog the bus (such as
.It dhu%d: silo overflow.
The character input silo overflowed
before it could be serviced. This can happen if a hard error occurs
is running with elevated priority, as the system may
then print a message on the console with interrupts disabled.
The driver currently does not make full use of the hardware
flow-control or hard-wired
Although the devices are not the same, a
autoconfiguration code that it is a
The 4 40-way cables are a pain.
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