NAME
dmc
-
DEC
DMC-11/DMR-11
point-to-point serial communications device
SYNOPSIS
dmc0 at uba0 csr 167600
DESCRIPTION
NOTE: This driver has not been ported from
4.4BSD
yet.
The
dmc
interface provides access to a point-to-point communications
device which runs at either 1 Mb/s or 56 Kb/s.
DMC-11s
communicate
using the
DEC DDCMP
link layer protocol.
The
dmc
interface driver also supports a
DEC
DMR-11
providing point-to-point
communication running at data rates from 2.4 Kb/s to 1 Mb/s.
DMR-11s
are a more recent design and thus are preferred over
DMC-11s.
The
NXMT
and
NRCV
constants in the driver may be increased in this case,
as the
DMR
can accept up to 64 transmit and receive buffers, as opposed
to 7 for the
DMC.
The configuration flags specify how to set up the device,
0 full duplex DDCMP (normal mode)
1 DDCMP Maintenance mode (generally useless)
2 DDCMP Half Duplex, primary station
3 DDCMP Half Duplex, secondary station
The host's address must be specified with an
SIOCSIFADDR
ioctl(2),
and the destination address specified with a
SIOCSIFDSTADDR
ioctl(2),
before the interface will transmit or receive any packets.
ROUTING
The driver places a
HOST
entry in the kernel routing tables for the
address given in the
SIOCSIFDSTADDR
ioctl(2).
To use the
DMC
as a
link between local nets, the route to the remote net must be added manually
with the
route(8)
command, or by the use of the routing process
routed(8)
on each end of the link.
DIAGNOSTICS
- dmc%d: bad control %o.
-
A bad parameter was passed to the
dmcload
routine.
- dmc%d: unknown address type %d.
-
An input packet was received which contained a type of
address unknown to the driver.
- DMC fatal error 0%o.
-
A fatal error in
DDMCP
occurred, causing the device to be restarted.
- DMC soft error 0%o.
-
A non-fatal error in
DDMCP
has occurred.
- dmc%d: af%d not supported.
-
The interface was handed a message which has
addresses formatted in an unsuitable address family.
SEE ALSO
inet(4),
intro(4)
HISTORY
The
dmc
driver appeared in
4.2BSD.
BUGS
The current version of the driver uses a link-level encapsulation
so that multiple protocol types may be used.
It is thus incompatible with earlier drivers,
including the
4.2BSD
version.