DHU
Section: Devices and Network Interfaces (4)
Updated: vax
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BSD mandoc
BSD 4.3
NAME
dhu
- DHU-11
communications multiplexer
SYNOPSIS
device dhu0 at uba0 csr 0160440 vector dhurint dhuxint
DESCRIPTION
A
DHU-11
provides 16 communication lines.
An optional argument
flags
may be supplied with the device specification
in the config file indicating
that the line corresponding to
bit number
i
is not properly
connected, and should be treated as hard-wired with carrier
always present. Thus specifying
`flags'
0x0004
for
dhu0
would cause line
ttyS2
to be treated in this way.
Normal I/O
control parameters for individual lines are managed by
ioctl(2)
calls.
Individual
DHU-11
lines may be configured to run at any of 13 speeds
(50, 200 and 38400 baud are not available);
the speed may be set via
getty(8)
or
stty(1)
or may be communicated by other programs which
utilize
ioctl
such as
ifcongif(8),
see
tty(4).
The
DHU-11
driver normally uses input silos
and delays receiver interrupts by 20 milliseconds
rather than taking an interrupt on each input character.
FILES
- /dev/tty[S-Z][0-9a-f]
-
DIAGNOSTICS
- dhu(%d,%d): NXM fault.
-
No response from
UNIBUS
on a
DMA
transfer
within a timeout period. This is often followed by a
UNIBUS
adapter
error. This occurs most frequently when the
UNIBUS
is heavily loaded
and when devices which hog the bus (such as
RK07 s
are present.
It is not serious.
- dhu%d: silo overflow.
-
The character input silo overflowed
before it could be serviced. This can happen if a hard error occurs
when the
CPU
is running with elevated priority, as the system may
then print a message on the console with interrupts disabled.
NOTES
The driver currently does not make full use of the hardware
capabilities of the
DHU-11
for dealing with
XON/XOFF
flow-control or hard-wired
lines for example.
Although the devices are not the same, a
DHU-11
can convince the
DH-11
autoconfiguration code that it is a
DH-11
The 4 40-way cables are a pain.
SEE ALSO
tty(4)
HISTORY
The
driver appeared in
BSD 4.3
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- FILES
-
- DIAGNOSTICS
-
- NOTES
-
- SEE ALSO
-
- HISTORY
-
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