DHU(4)           NetBSD Programmer's Manual (VAX Architecture)          DHU(4)

NNAAMMEE
     ddhhuu - DHU-11/DHV-11 communications multiplexer

SSYYNNOOPPSSIISS
     ddhhuu00 aatt uubbaa00 ccssrr 00116600444400

DDEESSCCRRIIPPTTIIOONN
     A DHU-11 provides 16 communication lines.

     Normal I/O control parameters for individual lines are managed by
     ioctl(2) calls.  Individual DHU-11 lines may be configured to run at any
     of 13 speeds (50, 200 and 38400 baud are not available); the speed may be
     set via getty(8) or stty(1) or may be communicated by other programs
     which utilize ioctl such as ifconfig(8),  see tty(4).

     The DHU-11 driver normally uses input silos and delays receiver inter-
     rupts by 20 milliseconds rather than taking an interrupt on each input
     character.

FFIILLEESS
     /dev/tty[S-Z][0-9a-f]

NNOOTTEESS
     The driver currently does not make full use of the hardware capabilities
     of the DHU-11, for dealing with XON/XOFF flow-control or hard-wired lines
     for example.

     Although the devices are not the same, a DHU-11 can convince the DH-11
     autoconfiguration code that it is a DH-11.

     The 4 40-way cables are a pain.

SSEEEE AALLSSOO
     tty(4)

HHIISSTTOORRYY
     The ddhhuu driver appeared in 4.3BSD.
     A new ddhhuu driver showed up in NetBSD 1.1A.

BBUUGGSS
     Even if the ddhhuu hardware supports DMA, the driver cannot make use of this
     capability.

4.3 Berkeley Distribution        June 5, 1993                                1