NAME
dmz
-
DMZ-32
serial terminal multiplexor
SYNOPSIS
dmz0 at uba? csr 0160540 vector dmzrinta dmzxinta dmzrintb dmzxintb dmzrintc dmzxintc
DESCRIPTION
NOTE: This driver has not been ported from
4.4BSD
yet.
The
dmz
device provides 24 lines of asynchronous serial line support.
Modem control on all ports is available
as an option for the H3014 distribution panel.
An optional argument
flags
may be supplied with the device specification for
dmz
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 0x000004'
for
dmz0
would cause line
ttya2
to be treated in this way.
Normal
I/O
control parameters for individual lines are managed by
ioctl(2)
calls.
Line speeds (there are 16 choices for the
DMZ)
may be initiated via
getty(8)
and
stty(1)
or may be communicated by other programs which
use
ioctl(2)
such as
ifconfig(8),
see
tty(4).
The
dmz
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.
FILES
/dev/tty[abcefg][0-9a-n]
-
DIAGNOSTICS
- dmz%d: NXM line %d.
-
No response from the
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.
- dmz%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
The
dmz
driver appeared in
4.3BSD.
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.