usr/share/man/cat4/vax/dhu.0



DHU(4)                        1986                         DHU(4)


N\bNA\bAM\bME\bE
     dhu - DHU-11 communications multiplexer

S\bSY\bYN\bNO\bOP\bPS\bSI\bIS\bS
     d\bde\bev\bvi\bic\bce\be d\bdh\bhu\bu0\b0 a\bat\bt u\bub\bba\ba0\b0 c\bcs\bsr\br 0\b01\b16\b60\b04\b44\b40\b0 v\bve\bec\bct\bto\bor\br d\bdh\bhu\bur\bri\bin\bnt\bt d\bdh\bhu\bux\bxi\bin\bnt\bt

D\bDE\bES\bSC\bCR\bRI\bIP\bPT\bTI\bIO\bON\bN
     A DHU-11 provides 16 communication lines.

     Each line attached to the DHU-11 communications multiplexer
     behaves as described in _\bt_\bt_\by(4).  Input and output for each
     line may independently be set to run at any of 13 speeds
     (50, 200 and 38400 baud are not available); see _\bt_\bt_\by(4) for
     the encoding.

     Bit _\bi of flags may be specified for a DHU-11 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 dhu0
     would cause line ttyS2 to be treated in this way.

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

F\bFI\bIL\bLE\bES\bS
     /dev/tty[S-Z][0-9a-f]

S\bSE\bEE\bE A\bAL\bLS\bSO\bO
     tty(4)

D\bDI\bIA\bAG\bGN\bNO\bOS\bST\bTI\bIC\bCS\bS
     d\bdh\bhu\bu(\b(%\b%d\bd,\b,%\b%d\bd)\b):\b: N\bNX\bXM\bM f\bfa\bau\bul\blt\bt.  No response from UNIBUS on a DMA
     transfer within a timeout period.  This is often followed by
     a UNIBUS adapter error.  This occurs most frequently when
     the UNIBUS is heavily loaded and when devices which hog the
     bus (such as RK07s) are present.  It is not serious.

     d\bdh\bhu\bu%\b%d\bd:\b: s\bsi\bil\blo\bo o\bov\bve\ber\brf\bfl\blo\bow\bw.  The character input silo overflowed
     before it could be serviced.  This can happen if a hard
     error occurs when the CPU is running with elevated priority,
     as the system may then print a message on the console with
     interrupts disabled.

N\bNO\bOT\bTE\bES\bS
     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.


Printed 7/27/90               April                             1


DHU(4)                        1986                         DHU(4)


     The 4 40-way cables are a pain.


Printed 7/27/90               April                             2