1.\" $NetBSD: dcm.4,v 1.7 2001/09/11 06:30:03 gmcgarry Exp $ 2.\" 3.\" Copyright (c) 1990, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" the Systems Programming Group of the University of Utah Computer 8.\" Science Department. 9.\" 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: @(#)dcm.4 8.1 (Berkeley) 6/9/93 39.\" 40.Dd June 9, 1993 41.Dt DCM 4 hp300 42.Os 43.Sh NAME 44.Nm dcm 45.Nd 46.Tn HP98642A 47serial communications multiplexer 48.Sh SYNOPSIS 49.Cd "dcm* at dio? scode ? flags 0xe" 50.Sh DESCRIPTION 51The 52.Tn 98642A 53is a four port 54.Tn EIA 55.Tn RS-232C 56.Pf ( Tn CCITT 57.Tn V.28 ) 58communications 59multiplexer. The 60.Tn 98642A 61has three direct-connect ports and one port with 62full modem control. 63.Pp 64Input and output for each line may set to one of following baud rates; 6550, 75, 110, 134.5, 150, 300, 600, 1200, 1800, 2400, 4800, 669600, 19200, 38400. 67.Pp 68.Ar Flags 69is usually specified as 0xe since 3 of the 4 ports (1-3) do not support 70modem control and should be treated as hard-wired with carrier always present. 71If port 0 does not have the need for modem control then flags can be specified 72as 73.Ql 0xf . 74.Pp 75Each port on the 76.Tn 98642A 77has a 128 byte input silo and a 16 byte output silo. 78Interrupts happen on a per character basis unless the interrupt 79rate for the card reaches 70 interrupts per second at which time the 80driver changes to a 16.7ms (60 interrupts per second) polling scheme until 81the interrupt rate drops. 82.Sh FILES 83.Bl -tag -width /dev/tty0[0-9a-f] -compact 84.It Pa /dev/tty0[0-9a-f] 85.El 86.Sh DIAGNOSTICS 87.Bl -diag 88.It dcm%d port%d: silo overflow 89Input Silo has overflowed and incoming data 90has been lost. 91.Pp 92.It dcm%d port%d: uart overflow 93The 3 character buffer in the uart has 94overflowed. 95.El 96.Sh SEE ALSO 97.Xr dio 4 , 98.Xr tty 4 99.Sh BUGS 100Total throughput per card, all ports together, is limited to 76800 bits per 101second continuous input rate. 102