.\"	$OpenBSD: com.4,v 1.49 2021/12/16 08:03:17 anton Exp $
.\"	$NetBSD: com.4,v 1.5 1996/03/16 00:07:08 thorpej Exp $
.\"
.\" Copyright (c) 1990, 1991 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" the Systems Programming Group of the University of Utah Computer
.\" Science Department.
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     from: @(#)dca.4	5.2 (Berkeley) 3/27/91
.\"
.Dd $Mdocdate: December 16 2021 $
.Dt COM 4
.Os
.Sh NAME
.Nm com
.Nd serial communications interface
.Sh SYNOPSIS
.Cd "# com attachments"
.Cd "#"
.Cd "# i386"
.Cd "com0 at isa? port 0x3f8 irq 4"
.Cd "com1 at isa? port 0x2f8 irq 3"
.Cd "com2 at isa? port 0x3e8 irq 5"
.Cd "com3 at isa? port 0x2e8 irq 9"
.Cd "com* at isapnp?"
.Cd "com* at pcmcia?"
.Cd "com* at puc?"
.Cd "com* at cardbus?"
.Pp
.Cd "com* at addcom?"
.Cd "com* at ast?"
.Cd "com* at boca?"
.Cd "com* at hsq?"
.Pp
.Cd "# alpha and amd64"
.Cd "com0 at isa? port 0x3f8 irq 4"
.Cd "com1 at isa? port 0x2f8 irq 3"
.Pp
.Cd "# amd64 and arm64"
.Cd "com* at acpi?"
.Pp
.Cd "# arm64 and armv7"
.Cd "com* at fdt?"
.Pp
.Cd "# hppa"
.Cd "com0 at gsc? offset 0x5000 irq 5"
.Cd "com0 at gsc? offset 0x823000 irq 5"
.Cd "com1 at gsc? offset 0x822000 irq 6"
.Cd "com2 at gsc? irq 13"
.Cd "com1 at dino? irq 11"
.Cd "com0 at ssio? irq 4"
.Cd "com1 at ssio? irq 3"
.Pp
.Cd "# loongson"
.Cd "com* at leioc?"
.Pp
.Cd "# macppc"
.Cd "com* at puc?"
.Cd "com* at pcmcia?"
.Cd "com* at cardbus?"
.Pp
.Cd "# octeon"
.Cd "com* at fdt?"
.Pp
.Cd "# riscv64"
.Cd "com* at fdt?"
.Pp
.Cd "# sparc64"
.Cd "com* at asio?"
.Cd "com* at ebus?"
.Cd "com* at puc?"
.Sh DESCRIPTION
The
.Nm com
driver provides support for NS8250-, NS16450-, NS16550-, ST16650-,
ST16C654-, and TI16750-based
.\" XR16850-
.Tn EIA
.Tn RS-232C
.Pf ( Tn CCITT
.Tn V.28 )
communications interfaces.
.Pp
The NS8250 and NS16450 have single
character buffers, the NS16550 has a 16 character buffer, while
the ST16650 has a 32 character buffer, and the TI16750 has a 64 character
buffer.
.\" The XR16850 has a 128 character buffer.
.Pp
Input and output for each line may be 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 -compact
.It Pa /dev/tty00
.It Pa /dev/tty01
.It Pa /dev/cua00
.It Pa /dev/cua01
.El
.Sh DIAGNOSTICS
.Bl -diag
.It com0: N silo overflows
The input
.Dq silo
has overflowed and incoming data has been lost.
.It com0: weird interrupt: iir=XXXX
The device has generated an unexpected interrupt
with the code listed.
.El
.Sh SEE ALSO
.Xr addcom 4 ,
.Xr asio 4 ,
.Xr ast 4 ,
.Xr boca 4 ,
.Xr cardbus 4 ,
.Xr dino 4 ,
.Xr ebus 4 ,
.Xr gsc 4 ,
.Xr hsq 4 ,
.Xr intro 4 ,
.Xr isa 4 ,
.Xr isapnp 4 ,
.Xr pcmcia 4 ,
.Xr puc 4 ,
.Xr ssio 4 ,
.Xr tty 4
.Sh HISTORY
The
.Nm
driver was originally derived from the
.Nm HP9000/300
.Nm dca
driver.
.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 .