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.