dhu man page on Ultrix

Printed from http://www.polarhome.com/service/man/?qf=dhu&af=0&tf=2&of=Ultrix

dhu(4)									dhu(4)

Name
       dhu - DHU11 communications interface

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

Description
       A DHU11 provides 16 communication lines with modem control.

       Each  line  attached to the DHU11 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 DHU11 to say that a line is not
       properly connected and that the line should be  treated	as  hard-wired
       with  carrier always present.  Thus, specifying ``flags 0x0004'' in the
       specification of would cause the third line tty02 to be treated in this
       way.

Diagnostics
       dhu%d %d: DMA ERROR
       The indicated channel failed to transfer DMA data within 21.3 microsec‐
       onds of the bus request being acknowledged or there was a memory parity
       error.	This is often followed by a UNIBUS adapter error, which occurs
       most frequently when the UNIBUS is heavily loaded and when devices such
       as rk07s, which monopolize the bus, are present.

       dhu%d: DHU 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.

       dhu%d: DIAG. FAILURE
       The DHU11 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 elevated priority.  Interrupts  are	disabled,  and
       the system then prints a message on the console.

Files
       (modem lines only)

See Also
       tty(4), MAKEDEV(8)

				      VAX				dhu(4)
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