dmc(4)									dmc(4)

Name
       dmc - DMC11/DMR11 communications interface

Syntax
       device dmc0 at uba0 csr 0167600 flags 0x???? vector dmcrint dmcxint

Description
       The interface provides access to a point-to-point communications device
       that runs at either 1 Mb/s or 56 Kb/s.  DMC11s  communicate  using  the
       DDCMP link layer protocol.

       The  interface  driver  also  supports a DMR11 providing point-to-point
       communication running at data rates from 2.4 Kb/s to  1	Mb/s.	DMR11s
       are a more recent design and are preferred over DMC11s.

       The host address must be specified with an SIOCSIFADDR ioctl before the
       interface will transmit or receive any packets.

       Several protocols can be multiplexed over a link simultaneously.	  Con‐
       versely,	 a  can	 be  set up such that only one protocol family can use
       that device.  If the latter approach is taken, an SIOCSTATE ioctl  must
       be issued by the protocol family requesting device ownership.  The fam‐
       ily address must appear in  the	``if_family''  structure  member,  and
       ``if_nomuxhdr''	must  be  set.	Before requesting ownership, make sure
       that access to the device for all other protocol families is disabled.

       The first byte of the flags word can be set up to  indicate  what  mode
       the  device  should  use.  The supported modes are 0 for full duplex, 1
       for maintenance mode, and 2 for	half  duplex.	In  addition,  if  the
       device is a the number of outstanding transmit buffers can be increased
       from a default of 7 to a maximum of 24 buffers by specifying a hexadec‐
       imal  value  in the second byte of the flags word.  For example, if the
       flags word is set to 0x1800, 24 transmit buffers will be allocated on a
       device set up to run full duplex.

Restrictions
       Note  that  maintenance	mode should be used only to diagnose data link
       problems.  It is not intended to be used for normal data link traffic.

Diagnostics
       dmcprobe: can't start device
       The could not be started at boot time.

       dmcinit:	 DMC not running
       The unexpectedly stopped running.

       dmc%d: done unalloc rbuf
       The returned a receive or transmit buffer that was not allocated to it.

       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 that contained a type of  address  unknown
       to the driver.

       dmc%d: bad packet address 0x%x
       The device returned a buffer with an unexpected buffer address.

       dmc%d: can't handle af%d
       The  interface  was handed a message that has addresses formatted in an
       unsuitable address family.  Formerly reported as dmc%d: af%d  not  sup‐
       ported.

       dmc%d: internal loopback enable requested
       The device is being put in internal loopback at a user's request.

       dmc%d: internal loopback disable requested
       The device is being taken out of internal loopback at a user's request.

       DMC FATAL ERROR 0%o

       DMC SOFT ERROR 0%o

See Also
       inet(4f), intro(4n)

				      VAX				dmc(4)

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