dhv(4) [ultrix man page]
dhv(4) Kernel Interfaces Manual dhv(4) Name dhv - DHV11 communications interface Syntax device dhu0 at uba0 csr 0160440 flags 0x?? vector dhurint dhuxint Description A DHV11 provides eight communication lines with partial modem control, adequate for UNIX dialup use. Each line attached to the DHV11 com- munications interface behaves as described in and can be set to run at any of 16 speeds. See for the encoding. Bit i of flags may be specified for a DHV to say that a line is not properly connected and that the line should be treated as hardwired, with carrier always present. Thus, specifying ``flags 0x04'' in the specification of dhu0 would cause line tty02 to be treated in this way. The driver normally interrupts on each input character. The and devices operate under the control of the driver. Diagnostics dhu%d: receive 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 ele- vated priority, as the system will then 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. dhu%d:%d DMA ERROR A DMA transfer error has occurred. The unit number and line number are printed. This means that the channel indicated has failed to transfer DMA data within 10.7 microseconds of the bus request being acknowledged or that there is a memory parity error. This may cause a few output characters to be lost. dhu%d: DIAG. FAILURE This indicates that the internal diagnostics have detected an error. 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. Files Dialups See Also tty(4), MAKEDEV(8) dhv(4)
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DH(4) Kernel Interfaces Manual DH(4) NAME
dh - DH-11/DM-11 communications multiplexer SYNOPSIS
/sys/conf/SYSTEM: NDH dh_units # DH11; NDH is in units of boards (16 each) NDM dm_units # DM11; NDM is in units of boards (16 each) /etc/dtab: #Name Unit# Addr Vector Br Handler(s) # Comments dm ? 170500 310 4 dmintr # dm11 dh modem control dh ? 160020 320 5 dhrint dhxint # dh11 terminal mux major device number(s): raw: 3 minor device encoding: bits 0017 specify line on DH unit bits 0060 specify DH unit bit 0100 specify RTS/CTS (``hardware'') flowcontrol bit 0200 specifies non-blocking open (``CD always on'') DESCRIPTION
A dh-11 provides 16 communication lines; dm-11's may be optionally paired with dh-11's to provide modem control for the lines. If there are fewer dm-11's than dh-11's, the dm-11's are assumed to be paired with the first dm_units dh-11's. Each line attached to the DH-11 communications multiplexer behaves as described in tty(4). Input and output for each line may indepen- dently be set to run at any of 16 speeds; see tty(4) for the encoding. Bit 0200 of the minor device number for DH lines may be set to say that a line is not properly connected, and that the line should be treated as hard-wired with carrier always present. Thus creating the special character device node "3, 130" via mknod /dev/ttyh2 c 3 130 would cause line ttyh2 to be treated in this way. Bit 0100 of the minor device number enables RTS/CTS (also called ``hardware'') flow con- trol. It is enabled by adding 64 to the minor device number: mknod /dev/ttyh2 c 3 194 The dh driver monitors the rate of input on each board, and switches between the use of character-at-a-time interrupts and input silos. While the silo is enabled during periods of high-speed input, the driver polls for input 30 times per second. FILES
/dev/tty[h-k][0-9a-f] /dev/ttyd[0-9a-f] /dev/MAKEDEV script to create special files /dev/MAKEDEV.local script to localize special files SEE ALSO
tty(4), dtab(5), autoconfig(8) DIAGNOSTICS
dh%d NXM. No response from UNIBUS on a dma transfer within a timeout period. This has never been observed on a PDP-11 and is a carryover from the VAX driver when it was ported. It is not serious. dh%d %d overruns. The character input silo overflowed before it could be serviced. This message is only printed at line close time. It is not serious but does indicate that the system was not able to keep up with the data flow. 3rd Berkeley Distribution May 31, 1997 DH(4)