NetBSD/share/man/man4/man4.i386/com.4

.\"	$NetBSD: com.4,v 1.6 1999/03/16 01:19:21 garbled Exp $
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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	5.2 (Berkeley) 3/27/91
.\"
.Dd August 6, 1993
.Dt COM 4 i386
.Os
.Sh NAME
.Nm com
.Nd
serial communications interface
.Sh SYNOPSIS
.Cd "com0 at isa? port" \&"IO_COM1\&" irq 4
.Cd "com1 at isa? port" \&"IO_COM2\&" irq 3
.Sh DESCRIPTION
The
.Nm
driver provides support for NS8250-, NS16450-, and NS16550-based
.Tn EIA
.Tn RS-232C
.Pf ( Tn CCITT
.Tn V.28 )
communications interfaces.  The NS8250 and NS16450 have single character
buffers, and the NS16550 has a 16 character buffer.
.Pp
Input and output for each line may set to one of following baud rates;
50, 75, 110, 134.5, 150, 300, 600, 1200, 1800, 2400, 4800, 9600,
19200, 38400, 57600, or 115200, or any other baud rate which is a factor
of 115200.
.Sh FILES
.Bl -tag -width Pa
.It Pa /dev/tty00
.It Pa /dev/tty01
.It Pa /dev/tty02
.El
.Sh DIAGNOSTICS
.Bl -diag
.It com%d: %d silo overflows
The input
.Dq silo
has overflowed and incoming data has been lost.
.It com%d: weird interrupt: iir=%x
The device has generated an unexpected interrupt
with the code listed.
.El
.Sh SEE ALSO
.Xr ast 4 ,
.Xr rtfps 4 ,
.Xr tty 4
.Sh HISTORY
The
.Nm
driver was originally derived from the
.Nm HP9000/300
.Nm dca
driver and is
.Ud
.Sh BUGS
Data loss is possible on busy systems with unbuffered UARTs at high speed.
.Pp
The name of this driver and the constants which define the locations
of the various serial ports are holdovers from
.Nm DOS .