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dhv(4) [bsd man page]

DHV(4)							     Kernel Interfaces Manual							    DHV(4)

dhv - DHV-11 communications multiplexer SYNOPSIS
/sys/conf/SYSTEM: NDHV dhv_units # DHV11 /etc/dtab: #Name Unit# Addr Vector Br Handler(s) # Comments dhv ? 160440 310 5 dhvrint dhvxint # dhv terminal mux major device number(s): raw: 24 minor device encoding: bits 0007 specify line on DHV unit bits 0070 specify DHV unit bit 0100 specifies RTS/CTS (``hardware'') flowcontrol bit 0200 specifies non-blocking open (``CD always on'') DESCRIPTION
A DHV-11 provides 8 communication lines. Each line attached to the DHV-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 and 200 baud are not available). While 38400 is available the underlying hardware is not fast enough to handle it and there will be pauses/gaps between characters. Bit 0200 of the minor device number for DHV 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 in the minor device number via mknod /dev/ttyS2 c 4 194 would enable RTS/CTS flow control. The DHV-11 has an input silo but does not have the programmable receiver delay that the DHU (and DHQ) have. Thus system services more interrupts (i.e. gets fewer characters per interrupt on average) with a DHV-11 than with a DHQ (in DHU mode). FILES
/dev/tty[S-Z][0-9a-f] SEE ALSO
dhv%d,%d NXM. No response from QBUS on a DMA transfer within a timeout period. This error has never been observed on a PDP-11 and is a carryover from the VAX driver when that was ported to 2BSD. dhv%d diag %o. Diagnostic information from the DHV11. This has never been observed. The DHV-11 hardware manual will be required to decode the value printed out. dhv%d: %d overruns. The character input silo overflowed before it could be serviced. This message is printed only when the line is closed. By only printing this when the line is closed further silo overruns are avoided (kernel printf statements are not interrupt driven). NOTES
The DHV lacks the receiver delay that the DHU (and DHQ) have. Thus it is extremely easy (indeed it's almost certain at higher data rates) for a DHV-11 to enter an interrupt per character mode and use 70-80% of the cpu. 3rd Berkeley Distribution May 31, 1997 DHV(4)

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LP(4)							     Kernel Interfaces Manual							     LP(4)

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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