DCM(4) | Device Drivers Manual (hp300) | DCM(4) |
dcm
— HP98642A
serial communications multiplexer
dcm* at dio? scode ? flags 0xe
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.
Total throughput per card, all ports together, is limited to 76800 bits per second continuous input rate.
February 17, 2017 | NetBSD 10.99 |