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Annotation of 43BSDTahoe/man/man4/vax/dhu.4, revision 1.1.1.1

1.1       root        1: .\" Copyright (c) 1985 Regents of the University of California.
                      2: .\" All rights reserved.  The Berkeley software License Agreement
                      3: .\" specifies the terms and conditions for redistribution.
                      4: .\"
                      5: .\"    @(#)dhu.4       6.2 (Berkeley) 4/27/86
                      6: .\"
                      7: .TH DHU 4 "April 27, 1986"
                      8: .UC 6
                      9: .SH NAME
                     10: dhu \- DHU-11 communications multiplexer
                     11: .SH SYNOPSIS
                     12: .B "device dhu0 at uba0 csr 0160440 vector dhurint dhuxint"
                     13: .SH DESCRIPTION
                     14: A DHU-11 provides 16 communication lines.
                     15: .PP
                     16: Each line attached to the DHU-11 communications multiplexer
                     17: behaves as described in
                     18: .IR tty (4).
                     19: Input and output for each line may independently
                     20: be set to run at any of 13 speeds (50, 200 and 38400 baud are not available);
                     21: see
                     22: .IR tty (4)
                     23: for the encoding.
                     24: .PP
                     25: Bit
                     26: .I i
                     27: of flags may be specified for a DHU-11 to say that a line is not properly
                     28: connected, and that the line should be treated as hard-wired with carrier
                     29: always present.  Thus specifying ``flags 0x0004'' in the specification of dhu0
                     30: would cause line ttyS2 to be treated in this way.
                     31: .PP
                     32: The DHU-11 driver normally uses input silos
                     33: and delays receiver interrupts by 20 milliseconds
                     34: rather than taking an interrupt on each input character.
                     35: .SH FILES
                     36: /dev/tty[S-Z][0-9a-f]
                     37: .SH "SEE ALSO"
                     38: tty(4)
                     39: .SH DIAGNOSTICS
                     40: \fBdhu(%d,%d): NXM fault\fR.  No response from UNIBUS on a DMA transfer
                     41: within a timeout period.  This is often followed by a UNIBUS adapter
                     42: error.  This occurs most frequently when the UNIBUS is heavily loaded
                     43: and when devices which hog the bus (such as RK07s) are present.
                     44: It is not serious.
                     45: .PP
                     46: \fBdhu%d: silo overflow\fR.  The character input silo overflowed
                     47: before it could be serviced.  This can happen if a hard error occurs
                     48: when the CPU is running with elevated priority, as the system may
                     49: then print a message on the console with interrupts disabled.
                     50: .SH NOTES
                     51: The driver currently does not make full use of the hardware
                     52: capabilities of the DHU-11, for dealing with XON/XOFF flow-control or hard-wired
                     53: lines for example.
                     54: .PP
                     55: Although the devices are not the same, a DHU-11 can convince the
                     56: DH-11 autoconfiguration code that it is a DH-11.
                     57: .PP
                     58: The 4 40-way cables are a pain.

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