.\"	$OpenBSD: dca.4,v 1.14 2010/01/02 19:55:35 schwarze Exp $
.\"
.\" Copyright (c) 1990, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
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.\" This code is derived from software contributed to Berkeley by
.\" the Systems Programming Group of the University of Utah Computer
.\" Science Department.
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.\"     from: @(#)dca.4	8.1 (Berkeley) 6/9/93
.\"
.Dd $Mdocdate: January 2 2010 $
.Dt DCA 4 hp300
.Os
.Sh NAME
.Nm dca
.Nd
.Tn HP 98644A
serial communications interface
.Sh SYNOPSIS
.Cd "dca0 at dio? scode 9 flags 1" Pq "on-board serial interfaces"
.Cd "dca* at dio?"
.Sh DESCRIPTION
The
.Tn 98644A
is a single port
.Tn EIA
.Tn RS-232C
.Pf ( Tn CCITT
.Tn V.28 )
communications interface with a single character buffer.
Such an interface is built-in to all series 300 machines.
.Pp
Input and output for each line may be set to one of the following baud rates:
50, 75, 110, 134.5, 150, 300, 600, 1200, 1800, 2400, 4800, 9600,
19200, 38400.
.Pp
An optional argument
.Ar flags
may be set to 1 if the line should be treated as hard-wired
with carrier always present or 0 if modem control is desired.
.Sh FILES
.Bl -tag -width Pa -compact
.It Pa /dev/tty[0-3]
.It Pa /dev/cua[0-3]
.El
.Sh DIAGNOSTICS
.Bl -diag
.It dca%d: silo overflow.
The single-character input
.Dq silo
has overflowed and incoming data has been lost.
.El
.Sh SEE ALSO
.Xr dio 4 ,
.Xr intro 4 ,
.Xr tty 4
.Sh BUGS
Data loss is possible on busy systems with baud rates greater than 300.
The
.Nm
has never been tested with modem control enabled or on anything but the
built-in interface.