dhb(4)dhb(4)Namedhb - DHB32 communications multiplexer
device dmb0 at vaxbi? node? flags 0x????
vector dmbsint dmbaint dmblint
A DHB32 device provides 16 asynchronous communication lines with full
modem control. The DHB32 and the DMB32 share a common software device
driver. For this reason, the configuration line is the same for both
the DHB32 and DMB32.
Each line attached to a DHB32 serial line port behaves as described in
Input and output for each line can independently be set to run at any
of 16 speeds. See for the encoding.
Bit i of flags may 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 will operate 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
DHB32 to be treated as hardwired with carrier always present. In this
example, the remainder of the lines will be modem control lines.
dmbinit: async lines unavailable
This message is produced at system boot time if the DHB32 fails its
internal self test indicating that the asynchronous lines have failed
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 may indicate that configuration con‐
straints have been reached.
dmb%d: DMA Error. tbuf = 0x%x
A DMA output transfer failed. This problem can result from a memory
error or an invalid pte (page table entry). For a description of the
error code in the ``tbuf'' register. See the DHB32 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 DHB32 documentation.
dmb%d: Internal Error. tbuf = 0x%x
Indicates that the DHB32 detected an internal error. For a description
of the error code in the ``tbuf'' register. See the DHB32 User Guide.
(modem lines only)
See Alsotty(4), MAKEDEV(8), dmbsp(4)dhb(4)