.\" 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
.\"
.TH DMC 4 ""
.UC 5
.SH NAME
dmc \- DEC DMC-11/DMR-11 point-to-point communications device
.SH SYNOPSIS
.B "device dmc0 at uba0 csr 167600 vector dmcrint dmcxint"
.SH DESCRIPTION
The
.I 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.
.PP
The
.I 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.
.PP
The configuration flags specify how to set up the device, 
.br
0 -- full duplex DDCMP
.br
1 -- DDCMP Maintence mode (generally useless)
.br
2 -- DDCMP Half Duplex, primary station
.br
3 -- DDCMP Half Duplex, secondary station
.ti
.PP
Several device error counters are available via "adb", for
more information see the adb script /usr/lib/adb/dmcstats, or the
DMC11 technical manual.
.PP
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.
.SH ROUTING
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.
.SH DIAGNOSTICS
.BR "dmc%d: bad control %o" .
A bad parameter was passed to the
.I dmcload
routine.
.PP
.BR "dmc%d: unknown address type %d" .
An input packet was received which contained a type of
address unknown to the driver.
.PP
.BR "DMC FATAL ERROR 0%o" .
A fatal error in DDMCP occured, causing the device to be restarted.
.PP
.BR "DMC SOFT ERROR 0%o" .
A non-fatal error in DDMCP has occured. 
.PP
.BR "dmc%d: af%d not supported" . 
The interface was handed a message which has
addresses formatted in an unsuitable address family.
.SH SEE ALSO
intro(4N), inet(4F)