From 90a856fd0d255166459eaf4a9067f5a316209b2b Mon Sep 17 00:00:00 2001 From: Kirk McKusick Date: Thu, 16 May 1985 00:18:24 -0800 Subject: [PATCH 1/1] manual page distributed with 4.1BSD SCCS-vsn: share/man/man4/man4.vax/dh.4 4.1 --- usr/src/share/man/man4/man4.vax/dh.4 | 65 ++++++++++++++++++++++++++++ 1 file changed, 65 insertions(+) create mode 100644 usr/src/share/man/man4/man4.vax/dh.4 diff --git a/usr/src/share/man/man4/man4.vax/dh.4 b/usr/src/share/man/man4/man4.vax/dh.4 new file mode 100644 index 0000000000..f61618f587 --- /dev/null +++ b/usr/src/share/man/man4/man4.vax/dh.4 @@ -0,0 +1,65 @@ +.\" Copyright (c) 1980 Regents of the University of California. +.\" All rights reserved. The Berkeley software License Agreement +.\" specifies the terms and conditions for redistribution. +.\" +.\" @(#)dh.4 4.1 (Berkeley) %G% +.\" +.TH DH 4 4/1/81 +.UC 4 +.SH NAME +dh, dm \- DH-11/DM-11 communications multiplexer +.SH SYNOPSIS +device dh0 at uba0 csr 0160020 vector dhrint dhxint +.br +device dm0 at uba0 csr 0170500 vector dmintr +.SH 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. +.PP +Each line attached to the DH-11 communications multiplexer +behaves as described in +.IR tty (4). +Input and output for each line may independently +be set to run at any of 16 speeds; +see +.IR tty (4) +for the encoding. +.PP +Bit +.I i +of flags may be specified for a dh to say that a line is not properly +connected, and that the line should be treated as hard-wired with carrier +always present. Thus specifying ``flags 0x0004'' in the specification of dh0 +would cause line ttyh2 to be treated in this way. +.PP +If the Berknet line driver +.IR bk (4) +is included in the system, then the dh driver will use its input silos +and poll for input at each clock tick (normally 1/50'th or 1/60'th of a +second) rather than taking an interrupt on each input character. +.SH FILES +/dev/tty[hi][0-9a-f] +.br +/dev/ttyd[0-9a-f] +.SH "SEE ALSO" +tty(4) +.SH DIAGNOSTICS +\fBdh%d: NXM\fR. 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 rk07's) are present. +It is not serious. +.PP +\fBdh%d: silo overflow\fR. The 64 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 will +then print a message on the console with interrupts disabled. If the +Berknet +.IR net (1) +is running on a +.I dh +line at high speed (e.g. 9600 baud), there is only 1/15th of a second of +buffering capacity in the silo, and overrun is possible. This may +cause a few input characters to be lost to users and a network +packet is likely to be corrupted, but the network will recover. +It is not serious. -- 2.20.1