1/0
INTERFACING
,---
---
- -
--
~
-
-----,
HOST
CPU
ATTENTION
INTERRUPT
82586
LAN
COPROCESSOR
SERIAL
INTERFACE
82501
ETHERNET
SERIAL
INTERFACE
TRANSCEIVER
CABLE
IEEE 802.3 COMPATIBLE
WORKSTATION
82C502
ETHERNET
TRANSCEIVER
CHIP
L
__________________
J
IEEE 802.3/ETHERNET
LINK
Figure
8-16. LAN Station
8.6.7.1 DEDICATED
CPU
G30107
Dedicating a
CPU
to control the 82586 results
in
a high-performance, high-cost interface.
The CPU, typically an 80186, an 80188, or a microcontroller, executes the data link layer
(a
functional division) of software and sometimes the network, transport, and session layers
as
well.
{For definitions of these layers, see the Local Area Networking (LAN) Components
User's Manual}. The dedicated
CPU
relieves the 80386 of these layers and provides a high-
level, message-oriented interface
that
can be treated in software as a standard
I/O
device.
In hardware, the interface
is
mapped into a dual-port memory.
8-28
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