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

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

N\bNA\bAM\bME\bE
     d\bdh\bhu\bu - 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.

     An optional argument _\bf_\bl_\ba_\bg_\bs may be supplied with the device specification
     in the config file indicating that the line corresponding to bit number _\bi
     is not properly connected, and should be treated as hard-wired with car-
     rier always present.  Thus specifying `flags 0x0004' for dhu0 would cause
     line _\bt_\bt_\by_\bS_\b2 to be treated in this way.

     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 ifcongif(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.

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

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.\b.  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 seri-
     ous.

     d\bdh\bhu\bu%\b%d\bd:\b: s\bsi\bil\blo\bo o\bov\bve\ber\brf\bfl\blo\bow\bw.\b.  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.

     The 4 40-way cables are a pain.

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

H\bHI\bIS\bST\bTO\bOR\bRY\bY
     The d\bdh\bhu\bu driver appeared in 4.3BSD.

4.3 Berkeley Distribution        June 5, 1993                                1