DMF
Section: Devices and Network Interfaces (4)
Updated: vax
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BSD mandoc
BSD 4.2
NAME
dmf
- DMF-32
terminal multiplexor
SYNOPSIS
device dmf0 at uba? csr 0160340 vector dmfsrint dmfsxint dmfdaint dmfdbint dmfrint dmfxint dmflint
DESCRIPTION
The
dmf
device provides 8 lines of asynchronous serial line support.
The first two of these have full modem control.
The device also provides a line printer port
similar to the
LP-11
Other features of the
DMF-32
are not supported.
During autoconfiguration, the driver examines the configuration of each
DMF-32
and adjusts the interrupt vectors so that fewer vector locations are used
if possible.
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'
0x04
for
dmf0
would cause line
ttyA2
to be treated in this way.
Flags should be set for all lines without hardware support for modem control.
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 serial line part of the
dmf
driver normally enables the input silos with a short timeout
(30 milliseconds); this allows multiple characters to be received
per interrupt during periods of high-speed input.
A line printer port on a
dmf
is designated by
a minor device number of the form
128+ n
See
MAKEDEV(8).
Column and lines per page may be changed from the default
132 columns and 66 lines by encoding the number of columns
in bits 8-15 of flags and the number of lines in bits 16-23.
This device does not provide the fancy output canonicalization
features of the
lp(4)
driver.
FILES
- /dev/tty[A-CE-I][0-7]
-
- /dev/ttyd[0-7]
-
- /dev/lp
-
DIAGNOSTICS
- dmf%d: NXM line %d.
-
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.
- dmf%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.
- dmfsrint, dmfsxint, dmfdaint, dmfdbint.
-
One of the unsupported parts of the dmf interrupted; something
is amiss, check your interrupt vectors for a conflict with another
device.
SEE ALSO
tty(4)
HISTORY
The
driver appeared in
BSD 4.2
BUGS
It should be possible to set the silo timeout with a configuration file option,
as the value is a trade-off between efficiency and response time for flow
control and character echo.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- FILES
-
- DIAGNOSTICS
-
- SEE ALSO
-
- HISTORY
-
- BUGS
-
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Time: 06:48:42 GMT, May 19, 2025