.\" SCCSID: @(#)dhq.4	2.1	3/10/87.TH dhq 4.SH Namedhq \- DHQ11 communications interface.SH Syntax.B "device dhu0 at uba? csr 0160440 flags 0x?? vector dhurint dhuxint".SH Description.NXR "DHQ11 communications interface".NXS "dhu interface" "DHQ11 communications interface".NXS "dhq keyword" "DHQ11 communications interface"A DHQ11 provides eight communication lines with modem control..PPEach line attached to the DHQ11 communications multiplexerbehaves as described in.MS tty 4 .Input and output for each line can be set independentlyto run at any of 16 speeds.See.MS tty 4for the coding..PPBit.I iof flags can be specified for a DHQ11to say that a line is not properlyconnected and that the line should be treated as hardwired with carrier always present.Thus, specifying ``flags 0x04'' in the specification of .PN dhu0would cause the third line to be treated in this way..NTThe .PN dhqdriver operates under the control of the.PN dhu driver..NE.SH Diagnostics.B "dhu%d %d: DMA ERROR" .brThe indicated channel failed to transfer DMAdata within 21.3 microseconds of the bus request being acknowledged orthere was a memory parity error..PP.B "dhu%d: DIAG. FAILURE".br The DHQ11 failed the diagnostics thatrun at initialization time..PP.B "dhu%d: recv. fifo overflow".br The character input fifo overflowedbefore it could be serviced.  This can happen if a hard error occurswhen the CPU is running with elevated priority.  Interrupts aredisabled, and the system then prints a message on the console..PP.B "dhu%d: DHU HARDWARE ERROR.  TX.DMA.START failed".br The dhq failed to clear the start bit.  Normally, this is cleared to signal that a DMA transfer has completed..SH Files.TP 15.PN /dev/tty??.TP.PN /dev/ttyd?Dialups.SH See Alsotty(4), MAKEDEV(8)