Copyright (c) 1983 Regents of the University of California.
All rights reserved. The Berkeley software License Agreement
specifies the terms and conditions for redistribution.

@(#)dmc.4 6.1 (Berkeley) 05/15/85

C 5 dmc - 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-11's 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-11's are a more recent design and thus are preferred over DMC-11's. The NXMT and NRCV constants in the driver should 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

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", for more information see the adb script /usr/lib/adb/dmcstats, or the DMC11 technical manual.

The host's address must be specified with an SIOCSIFADDR ioctl, and the destination address specified with a SIOCSIFDSTADDR ioctl, before the interface will transmit or recive 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 localnets, you must explicitly add the route with the route(8) command. "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 occured, causing the device to be restarted.

"DMC SOFT ERROR 0%o" . A non-fatal error in DDMCP has occured.

"dmc%d: af%d not supported" . The interface was handed a message which has addresses formatted in an unsuitable address family.

intro(4N), inet(4F)