DMC(4) | Device Drivers Manual (vax) | DMC(4) |
dmc
— DEC
DMC-11/DMR-11 point-to-point serial communications device
dmc0 at uba0 csr 167600
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 |
SIOCSIFADDR
ioctl(2), and the destination
address specified with a SIOCSIFDSTADDR
ioctl(2), 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(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.
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 earlier drivers, including the 4.2BSD version.
February 17, 2017 | NetBSD 10.99 |