.\" Copyright (c) 1980 Regents of the University of California.
.\" All rights reserved.  The Berkeley software License Agreement
.\" specifies the terms and conditions for redistribution.
.\"
.\"	@(#)dz.4	6.2 (Berkeley) 5/16/86
.\"
.TH DZ 4 "May 16, 1986"
.UC 4
.SH NAME
dz \- DZ-11 communications multiplexer
.SH SYNOPSIS
.B "device dz0 at uba0 csr 0160100 vector dzrint dzxint"
.SH DESCRIPTION
A DZ11 provides 8 communication lines with partial modem control,
adequate for UNIX dialup use.
Each line attached to the DZ11 communications multiplexer
behaves as described in
.IR tty (4)
and may 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 dz 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 0x04'' in the specification of dz0
would cause line tty02 to be treated in this way.
.PP
The
.I dz
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.
.SH FILES
/dev/tty[0-9][0-9]
.br
/dev/ttyd[0-9a-f]		dialups
.SH "SEE ALSO"
tty(4)
.SH DIAGNOSTICS
.PP
\fBdz%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.
It is not serious.