DCM
Section: Devices and Network Interfaces (4)
Updated: hp300
Index
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BSD mandoc
NAME
dcm
- HP
98642A communications multiplexer
SYNOPSIS
device dcm0 at scode? flags 0xe
DESCRIPTION
The
98642A
is a four port
EIA
RS-232C
( CCITT
V.28
communications
multiplexer. The
98642A
has three direct-connect ports and one port with
full modem control.
Input and output for each line may set to one of following baud rates;
50, 75, 110, 134.5, 150, 300, 600, 1200, 1800, 2400, 4800,
9600, 19200, 38400.
Flags
is usually specified as 0xe since 3 of the 4 ports (1-3) do not support
modem control and should be treated as hard-wired with carrier always present.
If port 0 does not have the need for modem control then flags can be specified
as
`0xf'
Each port on the
98642A
has a 128 byte input silo and a 16 byte output silo.
Interrupts happen on a per character basis unless the interrupt
rate for the card reaches 70 interrupts per second at which time the
driver changes to a 16.7ms (60 interrupts per second) polling scheme until
the interrupt rate drops.
FILES
- /dev/tty0[0-9a-f]
-
DIAGNOSTICS
- dcm%d port%d: silo overflow
-
Input Silo has overflowed and incoming data
has been lost.
- dcm%d port%d: uart overflow
-
The 3 character buffer in the uart has
overflowed.
SEE ALSO
tty(4)
HISTORY
The
driver
Ud
BUGS
Total throughput per card, all ports together, is limited to 76800 bits per
second continuous input rate.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- FILES
-
- DIAGNOSTICS
-
- SEE ALSO
-
- HISTORY
-
- BUGS
-
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