dmb(4)									dmb(4)

Name
       dmb - DMB32 communications multiplexor

Syntax
       device dmb0 at vaxbi? node? flags 0x????
	    vector dmbsint dmbaint dmblint

Description
       A  DMB32	 device	 provides  eight asynchronous communication lines with
       modem control.  The device driver also supports a connection to a  line
       printer through the line printer port of the DMB32.

       Each  line attached to a DMB32 serial line port behaves as described in
       Input and output for each line may independently be set to run  at  any
       of 16 speeds.  See for the encoding.

       Bit  i  of  flags  can  be specified for a to say that a line should be
       treated as a hardwired connection, with carrier always present.	If bit
       i  of  flags  is	 not  set, the line operates under full modem control.
       Modem lines will operate in accordance to the CD (carrier detect),  DSR
       (data  set  ready)  and	CTS  (clear  to send) leads.  Thus, specifying
       ``flags 0x0004'' in the specification of would  cause  line  2  on  the
       DMB32 to be treated as hardwired, with carrier always present.  In this
       example, the remainder of the lines will be modem control lines.

Restrictions
       The DMB32 provides a synchronous port, but this is not supported by the
       driver.

Diagnostics
       dmbinit: async lines unavailable
       This  message  is  produced at system boot time, if the DMB32 fails its
       internal self test, indicating that the asynchronous lines have	failed
       to configure.

       dmbinit: printer port unavailable
       This  message  is  produced at system boot time, if the DMB32 fails its
       internal self test, indicating that the printer port failed to  config‐
       ure.

       dmb%d: fifo overflow
       The  character input fifo overflowed before it could be serviced.  This
       can happen if the CPU is running with elevated priority for too long  a
       period  of  time.  Overflow errors can indicate that configuration con‐
       straints have been reached.

       dmb%d: DMA Error. tbuf = 0x%x
       A DMA output transfer failed.  This can be caused by a memory error  or
       an invalid pte (page table entry).  For a description of the error code
       in the ``tbuf'' register, see the DMB32 documentation.

       dmb%d: DMB Hardware Error. TX.DMA.START failed
       The failed to clear the start bit.  Normally, this is cleared to signal
       that a DMA transfer has completed.

       dmb%d: Modem Error. tbuf = 0x%x
       Indicates  a  problem  with a modem or its cable.  For a description of
       the error code in the ``tbuf'' register, see the DMB32 documentation.

       dmb%d: Internal Error. tbuf = 0x%x
       Indicates that the DMB32 detected an internal error.  For a description
       of  the	error  code in the ``tbuf'' register, see the DMB32 documenta‐
       tion.

       hfBdmb%d: uio move error
       An error occurred when copying a printer buffer from user space to sys‐
       tem space.

       dmbsint
       The  unsupported synchronous port of the DMB32 interrupted because of a
       problem.	 Check your interrupt vectors  for  a  conflict	 with  another
       device.

Files
       (modem lines only)

See Also
       tty(4), MAKEDEV(8), dmbsp(4)

									dmb(4)

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