4.3BSD-UWisc/man/man4/dmf.4

.\" Copyright (c) 1983 Regents of the University of California.
.\" All rights reserved.  The Berkeley software License Agreement
.\" specifies the terms and conditions for redistribution.
.\"
.\"	@(#)dmf.4	6.4 (Berkeley) 5/16/86
.\"
.TH DMF 4 "May 16, 1986"
.UC 5
.SH NAME
dmf \- DMF-32, terminal multiplexor
.SH SYNOPSIS
.B "device dmf0 at uba? csr 0160340"
.br
.ti +0.5i
.B "vector dmfsrint dmfsxint dmfdaint dmfdbint dmfrint dmfxint dmflint"
.SH DESCRIPTION
The 
.I 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.
.PP
Each line attached to a DMF-32 serial line port behaves as described
in
.IR tty (4).
Input and output for each line may independently be set to run at any
of 16 speeds; see
.IR tty (4)
for the encoding.
.PP
Bit
.I i
of flags may be specified for a
.I dmf
to to say that a line is not properly connected, and that the
line should be treated as hard-wired with carrier always present.
Thus specifying ``flags 0x04'' in the specification of 
.IR dmf 0
would cause line ttyA2 to be treated in this way.
Flags should be set for all lines without hardware support for modem control.
.PP
The serial line part of the
.I 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.
.PP
A line printer port on
.I dmf\^n
is designated by
a minor device number of the form 128+\fIn\fP.
Columns 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
.IR lp (4)
driver.
.SH FILES
/dev/tty[A-CE-I][0-7]
.br
/dev/ttyd[0-7]
.br
/dev/lp
.SH SEE ALSO
tty(4)
.SH DIAGNOSTICS
.BR "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 RK07s) are present.
It is not serious.
.PP
.BR "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.
.PP
.BR dmfsrint ,
.BR dmfsxint ,
.BR dmfdaint ,
.BR dmfdbint .
One of the unsupported parts of the dmf interrupted; something
is amiss, check your interrupt vectors for a conflict with another
device.
.SH 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.