1*62974Sbostic.\" Copyright (c) 1990, 1991, 1993 2*62974Sbostic.\" The Regents of the University of California. All rights reserved. 344674Sbostic.\" 444674Sbostic.\" This code is derived from software contributed to Berkeley by 544674Sbostic.\" the Systems Programming Group of the University of Utah Computer 644674Sbostic.\" Science Department. 762973Sbostic.\" 844674Sbostic.\" %sccs.include.redist.man% 944674Sbostic.\" 10*62974Sbostic.\" @(#)dcm.4 8.1 (Berkeley) 06/09/93 1144674Sbostic.\" 1247672Scael.Dd 1347672Scael.Dt DCM 4 hp300 1447672Scael.Os 1547672Scael.Sh NAME 1647672Scael.Nm dcm 1747672Scael.Nd 1847672Scael.Tn HP 1947672Scael98642A communications multiplexer 2047672Scael.Sh SYNOPSIS 2147672Scael.Cd "device dcm0 at scode? flags 0xe" 2247672Scael.Sh DESCRIPTION 2347672ScaelThe 2447672Scael.Tn 98642A 2547672Scaelis a four port 2647672Scael.Tn EIA 2747672Scael.Tn RS-232C 2847672Scael.Pf ( Tn CCITT 2947672Scael.Tn V.28 ) 3047672Scaelcommunications 3147672Scaelmultiplexer. The 3247672Scael.Tn 98642A 3347672Scaelhas three direct-connect ports and one port with 3444674Sbosticfull modem control. 3547672Scael.Pp 3644674SbosticInput and output for each line may set to one of following baud rates; 3744674Sbostic50, 75, 110, 134.5, 150, 300, 600, 1200, 1800, 2400, 4800, 3847672Scael9600, 19200, 38400. 3947672Scael.Pp 4047672Scael.Ar Flags 4147672Scaelis usually specified as 0xe since 3 of the 4 ports (1-3) do not support 4244674Sbosticmodem control and should be treated as hard-wired with carrier always present. 4344674SbosticIf port 0 does not have the need for modem control then flags can be specified 4447672Scaelas 4547672Scael.Ql 0xf . 4647672Scael.Pp 4747672ScaelEach port on the 4847672Scael.Tn 98642A 4947672Scaelhas a 128 byte input silo and a 16 byte output silo. 5044674SbosticInterrupts happen on a per character basis unless the interrupt 5144674Sbosticrate for the card reaches 70 interrupts per second at which time the 5244674Sbosticdriver changes to a 16.7ms (60 interrupts per second) polling scheme until 5344674Sbosticthe interrupt rate drops. 5447672Scael.Sh FILES 5547672Scael.Bl -tag -width /dev/tty0[0-9a-f] -compact 5647672Scael.It Pa /dev/tty0[0-9a-f] 5747672Scael.El 5847672Scael.Sh DIAGNOSTICS 5947672Scael.Bl -diag 6047672Scael.It dcm%d port%d: silo overflow 6147672ScaelInput Silo has overflowed and incoming data 6244674Sbostichas been lost. 6347672Scael.Pp 6447672Scael.It dcm%d port%d: uart overflow 6547672ScaelThe 3 character buffer in the uart has 6644674Sbosticoverflowed. 6747672Scael.El 6847672Scael.Sh SEE ALSO 6947672Scael.Xr tty 4 7047672Scael.Sh BUGS 7144674SbosticTotal throughput per card, all ports together, is limited to 76800 bits per 7244674Sbosticsecond continuous input rate. 73