DH
Section: Devices and Network Interfaces (4)
Updated: vax
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BSD mandoc
BSD 4
NAME
dh
- DH-11 / DM-11
multiplexer device interface
SYNOPSIS
device dh0 at uba0 csr 0160020 vector dhrint dhxint [flags
]
device dm0 at uba0 csr 0170500 vector dmintr [flags
]
DESCRIPTION
A
DH-11
provides 16 serial communication lines;
DM-11 s
may optionally be
paired with
DH-11 s
to provide modem control for the lines.
An optional argument
flags
may be supplied with the device specification
in the
config(8)
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
dh0
would cause line
ttyh2
to be treated in this way.
Normal I/O
control parameters for individual lines are managed by
ioctl(2)
calls.
Line speeds may be initiated via
getty(8)
and
stty(1)
or may be communicated by other programs which
utilize
ioctl
such as
ifcongif(8),
see
tty(4).
The
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.
FILES
- /dev/tty[h-o][0-9a-f]
-
- /dev/ttyd[0-9a-f]
-
DIAGNOSTICS
- dh%d: NXM.
-
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.
- dh%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 will
then print a message on the console with interrupts disabled.
It is not serious.
SEE ALSO
tty(4)
HISTORY
A
driver appeared in
AT&T System
v6 .
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- FILES
-
- DIAGNOSTICS
-
- SEE ALSO
-
- HISTORY
-
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Time: 06:48:31 GMT, May 19, 2025