1*47672Scael.\" Copyright (c) 1990, 1991 The Regents of the University of California. 244674Sbostic.\" 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. 744674Sbostic.\" %sccs.include.redist.man% 844674Sbostic.\" 9*47672Scael.\" @(#)dcm.4 5.2 (Berkeley) 03/27/91 1044674Sbostic.\" 11*47672Scael.Dd 12*47672Scael.Dt DCM 4 hp300 13*47672Scael.Os 14*47672Scael.Sh NAME 15*47672Scael.Nm dcm 16*47672Scael.Nd 17*47672Scael.Tn HP 18*47672Scael98642A communications multiplexer 19*47672Scael.Sh SYNOPSIS 20*47672Scael.Cd "device dcm0 at scode? flags 0xe" 21*47672Scael.Sh DESCRIPTION 22*47672ScaelThe 23*47672Scael.Tn 98642A 24*47672Scaelis a four port 25*47672Scael.Tn EIA 26*47672Scael.Tn RS-232C 27*47672Scael.Pf ( Tn CCITT 28*47672Scael.Tn V.28 ) 29*47672Scaelcommunications 30*47672Scaelmultiplexer. The 31*47672Scael.Tn 98642A 32*47672Scaelhas three direct-connect ports and one port with 3344674Sbosticfull modem control. 34*47672Scael.Pp 3544674SbosticInput and output for each line may set to one of following baud rates; 3644674Sbostic50, 75, 110, 134.5, 150, 300, 600, 1200, 1800, 2400, 4800, 37*47672Scael9600, 19200, 38400. 38*47672Scael.Pp 39*47672Scael.Ar Flags 40*47672Scaelis usually specified as 0xe since 3 of the 4 ports (1-3) do not support 4144674Sbosticmodem control and should be treated as hard-wired with carrier always present. 4244674SbosticIf port 0 does not have the need for modem control then flags can be specified 43*47672Scaelas 44*47672Scael.Ql 0xf . 45*47672Scael.Pp 46*47672ScaelEach port on the 47*47672Scael.Tn 98642A 48*47672Scaelhas a 128 byte input silo and a 16 byte output silo. 4944674SbosticInterrupts happen on a per character basis unless the interrupt 5044674Sbosticrate for the card reaches 70 interrupts per second at which time the 5144674Sbosticdriver changes to a 16.7ms (60 interrupts per second) polling scheme until 5244674Sbosticthe interrupt rate drops. 53*47672Scael.Sh FILES 54*47672Scael.Bl -tag -width /dev/tty0[0-9a-f] -compact 55*47672Scael.It Pa /dev/tty0[0-9a-f] 56*47672Scael.El 57*47672Scael.Sh DIAGNOSTICS 58*47672Scael.Bl -diag 59*47672Scael.It dcm%d port%d: silo overflow 60*47672ScaelInput Silo has overflowed and incoming data 6144674Sbostichas been lost. 62*47672Scael.Pp 63*47672Scael.It dcm%d port%d: uart overflow 64*47672ScaelThe 3 character buffer in the uart has 6544674Sbosticoverflowed. 66*47672Scael.El 67*47672Scael.Sh SEE ALSO 68*47672Scael.Xr tty 4 69*47672Scael.Sh HISTORY 70*47672ScaelThe 71*47672Scael.Nm 72*47672Scaeldriver 73*47672Scael.Ud 74*47672Scael.Sh BUGS 7544674SbosticTotal throughput per card, all ports together, is limited to 76800 bits per 7644674Sbosticsecond continuous input rate. 77