1.\" $OpenBSD: com.4,v 1.49 2021/12/16 08:03:17 anton Exp $ 2.\" $NetBSD: com.4,v 1.5 1996/03/16 00:07:08 thorpej Exp $ 3.\" 4.\" Copyright (c) 1990, 1991 The Regents of the University of California. 5.\" All rights reserved. 6.\" 7.\" This code is derived from software contributed to Berkeley by 8.\" the Systems Programming Group of the University of Utah Computer 9.\" Science Department. 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 3. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" from: @(#)dca.4 5.2 (Berkeley) 3/27/91 35.\" 36.Dd $Mdocdate: December 16 2021 $ 37.Dt COM 4 38.Os 39.Sh NAME 40.Nm com 41.Nd serial communications interface 42.Sh SYNOPSIS 43.Cd "# com attachments" 44.Cd "#" 45.Cd "# i386" 46.Cd "com0 at isa? port 0x3f8 irq 4" 47.Cd "com1 at isa? port 0x2f8 irq 3" 48.Cd "com2 at isa? port 0x3e8 irq 5" 49.Cd "com3 at isa? port 0x2e8 irq 9" 50.Cd "com* at isapnp?" 51.Cd "com* at pcmcia?" 52.Cd "com* at puc?" 53.Cd "com* at cardbus?" 54.Pp 55.Cd "com* at addcom?" 56.Cd "com* at ast?" 57.Cd "com* at boca?" 58.Cd "com* at hsq?" 59.Pp 60.Cd "# alpha and amd64" 61.Cd "com0 at isa? port 0x3f8 irq 4" 62.Cd "com1 at isa? port 0x2f8 irq 3" 63.Pp 64.Cd "# amd64 and arm64" 65.Cd "com* at acpi?" 66.Pp 67.Cd "# arm64 and armv7" 68.Cd "com* at fdt?" 69.Pp 70.Cd "# hppa" 71.Cd "com0 at gsc? offset 0x5000 irq 5" 72.Cd "com0 at gsc? offset 0x823000 irq 5" 73.Cd "com1 at gsc? offset 0x822000 irq 6" 74.Cd "com2 at gsc? irq 13" 75.Cd "com1 at dino? irq 11" 76.Cd "com0 at ssio? irq 4" 77.Cd "com1 at ssio? irq 3" 78.Pp 79.Cd "# loongson" 80.Cd "com* at leioc?" 81.Pp 82.Cd "# macppc" 83.Cd "com* at puc?" 84.Cd "com* at pcmcia?" 85.Cd "com* at cardbus?" 86.Pp 87.Cd "# octeon" 88.Cd "com* at fdt?" 89.Pp 90.Cd "# riscv64" 91.Cd "com* at fdt?" 92.Pp 93.Cd "# sparc64" 94.Cd "com* at asio?" 95.Cd "com* at ebus?" 96.Cd "com* at puc?" 97.Sh DESCRIPTION 98The 99.Nm com 100driver provides support for NS8250-, NS16450-, NS16550-, ST16650-, 101ST16C654-, and TI16750-based 102.\" XR16850- 103.Tn EIA 104.Tn RS-232C 105.Pf ( Tn CCITT 106.Tn V.28 ) 107communications interfaces. 108.Pp 109The NS8250 and NS16450 have single 110character buffers, the NS16550 has a 16 character buffer, while 111the ST16650 has a 32 character buffer, and the TI16750 has a 64 character 112buffer. 113.\" The XR16850 has a 128 character buffer. 114.Pp 115Input and output for each line may be set to one of following baud rates; 11650, 75, 110, 134.5, 150, 300, 600, 1200, 1800, 2400, 4800, 9600, 11719200, 38400, 57600, or 115200, or any other baud rate which is a factor 118of 115200. 119.Sh FILES 120.Bl -tag -width Pa -compact 121.It Pa /dev/tty00 122.It Pa /dev/tty01 123.It Pa /dev/cua00 124.It Pa /dev/cua01 125.El 126.Sh DIAGNOSTICS 127.Bl -diag 128.It com0: N silo overflows 129The input 130.Dq silo 131has overflowed and incoming data has been lost. 132.It com0: weird interrupt: iir=XXXX 133The device has generated an unexpected interrupt 134with the code listed. 135.El 136.Sh SEE ALSO 137.Xr addcom 4 , 138.Xr asio 4 , 139.Xr ast 4 , 140.Xr boca 4 , 141.Xr cardbus 4 , 142.Xr dino 4 , 143.Xr ebus 4 , 144.Xr gsc 4 , 145.Xr hsq 4 , 146.Xr intro 4 , 147.Xr isa 4 , 148.Xr isapnp 4 , 149.Xr pcmcia 4 , 150.Xr puc 4 , 151.Xr ssio 4 , 152.Xr tty 4 153.Sh HISTORY 154The 155.Nm 156driver was originally derived from the 157.Nm HP9000/300 158.Nm dca 159driver. 160.Sh BUGS 161Data loss is possible on busy systems with unbuffered UARTs at high speed. 162.Pp 163The name of this driver and the constants which define the locations 164of the various serial ports are holdovers from 165.Nm DOS . 166