1.\" $OpenBSD: com.4,v 1.5 2001/06/25 14:26:55 mpech 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. All advertising materials mentioning features or use of this software 19.\" must display the following acknowledgement: 20.\" This product includes software developed by the University of 21.\" California, Berkeley and its contributors. 22.\" 4. Neither the name of the University nor the names of its contributors 23.\" may be used to endorse or promote products derived from this software 24.\" without specific prior written permission. 25.\" 26.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36.\" SUCH DAMAGE. 37.\" 38.\" from: @(#)dca.4 5.2 (Berkeley) 3/27/91 39.\" 40.Dd July 12, 1998 41.Dt COM 4 42.Os 43.Sh NAME 44.Nm com , 45.Nm pccom 46.Nd serial communications interface 47.Sh SYNOPSIS 48.Cd "com0 at isa? port" \&"IO_COM1\&" irq 4 49.Cd "com1 at isa? port" \&"IO_COM2\&" irq 3 50.Pp 51.Cd "pccom0 at isa? port" \&"IO_COM1\&" irq 4 52.Cd "pccom1 at isa? port" \&"IO_COM2\&" irq 3 53.Cd "pccom* at isapnp?" 54.Sh DESCRIPTION 55The 56.Nm com 57and 58.Nm pccom 59drivers provide support for NS8250-, NS16450-, NS16550-, ST16650-, and 60TI16750-based 61.Tn EIA 62.Tn RS-232C 63.Pf ( Tn CCITT 64.Tn V.28 ) 65communications interfaces. 66The 67.Nm pccom 68driver also supports the XR16850 UART. 69.Pp 70The NS8250 and NS16450 have single 71character buffers, the NS16550 has a 16 character buffer, while 72the ST16650 has a 32 character buffer, and the TI16750 has a 64 character 73buffer. 74The XR16850 has a 128 character buffer. 75.Pp 76The 77.Nm com 78and 79.Nm pccom 80drivers are mutually exclusive; both may not be present in the same system at 81the same time. 82Attempting to compile such a system will fail. 83.Pp 84Input and output for each line may set to one of following baud rates; 8550, 75, 110, 134.5, 150, 300, 600, 1200, 1800, 2400, 4800, 9600, 8619200, 38400, 57600, or 115200, or any other baud rate which is a factor 87of 115200. 88.Sh FILES 89.Bl -tag -width Pa -compact 90.It Pa /dev/tty00 91.It Pa /dev/tty01 92.It Pa /dev/cua00 93.It Pa /dev/cua01 94.El 95.Sh DIAGNOSTICS 96.Bl -diag 97.It com%d: %d silo overflows 98The input 99.Dq silo 100has overflowed and incoming data has been lost. 101.It com%d: weird interrupt: iir=%x 102The device has generated an unexpected interrupt 103with the code listed. 104.El 105.Sh SEE ALSO 106.Xr ast 4 , 107.Xr rtfps 4 , 108.Xr tty 4 109.Sh HISTORY 110The 111.Nm 112driver was originally derived from the 113.Nm HP9000/300 114.Nm dca 115driver and is 116.Ud 117.Sh BUGS 118Data loss is possible on busy systems with unbuffered UARTs at high speed. 119.Pp 120The name of this driver and the constants which define the locations 121of the various serial ports are holdovers from 122.Nm DOS . 123