.\" SCCSID: @(#)dhv.4	2.1	3/10/87.TH dhv 4.SH Namedhv \- DHV11 communications interface.SH Syntax.B "device dhu0 at uba0 csr 0160440 flags 0x?? vector dhurint dhuxint".SH Description.NXR "DHV11 communications interface".NXS "dhv keyword" "DHV11 communications interface".NXS "dhu interface" "DHV11 communications interface"A DHV11 provides eight communication lines with partial modem control,adequate for UNIX dialup use.Each line attached to the DHV11 communications interfacebehaves as described in.MS tty 4and can be set to run at any of 16 speeds.  See.MS tty 4for the encoding..PPBit.I iof flags may be specified for a DHV to say that a line is not properlyconnected and that the line should be treated ashardwired, with carrieralways present.Thus, specifying ``flags 0x04'' in the specification of dhu0would cause line tty02 to be treated in this way..PPThe .PN dhvdriver normally interrupts on each input character..NTThe .PN cxa ,.PN cxb ,.PN cxy ,.PN dhv ,and.PN dhqdevices operate under the control of the .PN dhudriver..NE.SH Diagnostics.B "dhu%d: receive fifo overflow"  .brThe character input fifo overflowedbefore it could be serviced.  This can happen if a hard error occurswhen the CPU is running with elevated priority, as the system willthen print a message on the console with interrupts disabled.This can cause a few input characters to be lost to users.It is not serious..PP.B "dhu%d:%d DMA ERROR".brA DMA transfer error has occurred.The.PN dhvunit number and line number are printed.This means that the channel indicated has failed to transfer DMA datawithin 10.7 microseconds of the bus request being acknowledged or thatthere is a memory parity error.This may cause a few output characters to be lost..PP.B "dhu%d: DIAG. FAILURE".brThis indicates that the.PN dhvinternal diagnostics have detected an error..PP.B "dhu%d: DHU HARDWARE ERROR.  TX.DMA.START failed".brThe .PN dhv 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)