DMC(4) BSD/vax Kernel Interfaces Manual DMC(4)NAMEdmc — DEC DMC-11/ DMR-11 point-to-point communications device
device dmc0 at uba0 csr 167600 vector dmcrint dmcxint
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 Maintence mode (generally useless)
2 DDCMP Half Duplex, primary station
3 DDCMP Half Duplex, secondary station
Several device error counters are available via adb(1), for more informa‐
tion see the adb script /usr/lib/adb/dmcstats, or the DMC-11 technical
The host's address must be specified with an SIOCSIFADDR ioctl(2), and
the destination address specified with a SIOCSIFDSTADDR ioctl, before the
interface will transmit or receive any packets.
The driver places a HOST entry in the kernel routing tables for the
address given in the SIOCSIFDSTADDR ioctl. 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.
dmc%d: bad control %o. A bad parameter was passed to the dmcload rou‐
dmc%d: unknown address type %d. An input packet was received which con‐
tained 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 ALSOintro(4), inet(4)HISTORY
The dmc driver appeared in 4.2BSD.
The current version of the driver uses a link-level encapsulation so that
multiple protocol types may be used. It is thus incompatible with ear‐
lier drivers, including the 4.2BSD version.
4.2 Berkeley Distribution June 5, 1993 4.2 Berkeley Distribution