dhq(4)							     Kernel Interfaces Manual							    dhq(4)

Name
       dhq - DHQ11 communications interface

Syntax
       device dhu0 at uba? csr 0160440 flags 0x?? vector dhurint dhuxint

Description
       A DHQ11 provides eight communication lines with modem control.

       Each  line attached to the DHQ11 communications multiplexer behaves as described in Input and output for each line can be set independently
       to run at any of 16 speeds.  See for the coding.

       Bit i of flags can be specified for a DHQ11 to say that a line is not properly connected and that the line should be treated  as  hardwired
       with carrier always present.  Thus, specifying ``flags 0x04'' in the specification of would cause the third line to be treated in this way.
       The driver operates under the control of the driver.

Diagnostics
       dhu%d %d: DMA ERROR
       The indicated channel failed to transfer DMA data within 21.3 microseconds of the bus request being acknowledged or there was a memory par-
       ity error.

       dhu%d: DIAG. FAILURE
       The DHQ11 failed the diagnostics that run at initialization time.

       dhu%d: recv. fifo overflow
       The  character input fifo overflowed before it could be serviced.  This can happen if a hard error occurs when the CPU is running with ele-
       vated priority.	Interrupts are disabled, and the system then prints a message on the console.

       dhu%d: DHU HARDWARE ERROR.  TX.DMA.START failed
       The dhq failed to clear the start bit.  Normally, this is cleared to signal that a DMA transfer has completed.

Files
       Dialups

See Also
       tty(4), MAKEDEV(8)

																	    dhq(4)