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dhu(4) [bsd man page]

DHU(4)							     Kernel Interfaces Manual							    DHU(4)

NAME
dhu - DHU-11 communications multiplexer SYNOPSIS
/sys/conf/SYSTEM: NDHU dhu_units # DHU11 /etc/dtab: #Name Unit# Addr Vector Br Handler(s) # Comments du ? 160020 310 5 dhurint dhuxint # dhu11 terminal mux major device number(s): raw: 4 minor device encoding: bits 0017 specify line on DHU unit bits 0060 specify DHU unit bit 0100 specify RTS/CTS flow control bit 0200 specifies non-blocking open (``CD always on'') DESCRIPTION
A DHU-11 provides 16 communication lines. Each line attached to the DHU-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 13 speeds (50, 200 and 38400 baud are not available); see tty(4) for the encoding. Bit 0200 of the minor device number for DHU 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 "4, 130" via mknod /dev/ttyS2 c 4 130 would cause line ttyS2 to be treated in this way. Turning on bit 6 (adding 64) to the minor device number via mknod /dev/ttyS2 c 4 194 enables RTS/CTS flow control. The DHU-11 driver normally uses input silos and delays receiver interrupts by 20 milliseconds rather than taking an interrupt on each input character. FILES
/dev/tty[S-Z][0-9a-f] SEE ALSO
tty(4) DIAGNOSTICS
dhu(%d,%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 believed to be a carryover from the VAX driver when it was ported. It is not serious. dhu%d %d overruns. The character input silo overflowed before it could be serviced. This message is printed only at line close time rather than on each overrun error. Kernel printf's are not interrupt driven and caused more overruns by blocking interrupts for lengthy periods of time. NOTES
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. The 4 40-way cables are a pain. 3rd Berkeley Distribution May 31, 1997 DHU(4)

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LP(4)							     Kernel Interfaces Manual							     LP(4)

NAME
lp - line printer SYNOPSIS
/sys/conf/SYSTEM: NLP lp_printers # Line Printer LP_MAXCOL 132 # Maximum number of columns on line printers /etc/dtab: #Name Unit# Addr Vector Br Handler(s) # Comments lp ? 177514 200 4 lpintr # lp-11 line printer major device number(s): raw: 5 minor device encoding: bit 01 specifies 64-character set (instead of 96-character set) bits 06 are reserved bits 0370 specify line printer unit: <lp_unit> * 8 DESCRIPTION
Lp provides the interface to any of the standard DEC line printers on an LP-11 parallel interface. When it is opened or closed, a suitable number of page ejects is generated. Bytes written are printed. The unit number of the printer is specified by the minor device after removing the low 3 bits, which act as per-device parameters. Cur- rently only the lowest of the low three bits is interpreted: if it is set, the device is treated as having a 64-character set, rather than a full 96-character set. In the resulting half-ASCII mode, lower case letters are turned into upper case and certain characters are escaped according to the following table: { ( } ) ` ' | ! ~ ^ The driver correctly interprets carriage returns, backspaces, tabs, and form feeds. Lines longer than the maximum page width are trun- cated. The page width is specified via the LP_MAXCOL definition, set to 132 in the GENERIC distribution. FILES
/dev/lp /dev/MAKEDEV script to create special files /dev/MAKEDEV.local script to localize special files SEE ALSO
lpr(1), dtab(5), autoconfig(8) DIAGNOSTICS
None. BUGS
Although the driver supports multiple printers this has never been tried. 3rd Berkeley Distribution January 28, 1988 LP(4)
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