dmb(4)							     Kernel Interfaces Manual							    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 constraints 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  documen-
       tation.

       hfBdmb%d: uio move error
       An error occurred when copying a printer buffer from user space to system 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)