Intel
82801BA ICH2 Datasheet
5-17
Functional Description
5.2.4
CSMA/CD Unit
The ICH2 integrated LAN Controller CSMA/CD unit implements both the IEEE 802.3 Ethernet
10 Mbps and IEEE 802.3u Fast Ethernet 100 Mbps standards. It also supports the 1 Mbps Home
Phoneline Networking Alliance (HomePNA*) specification effort. It performs all the CSMA/CD
protocol functions such as transmission, reception, collision handling, etc. The LAN Controller
CSMA/CD unit interfaces to the 82562ET/EM 10/100 Mbps Ethernet or the 82562EH 1 Mbps
HomePNA*-compliant LAN Connect component through the ICH2’s LAN Connect interface
signals.
Full Duplex
When operating in full duplex mode, the LAN Controller can transmit and receive frames
simultaneously. Transmission starts regardless of the state of the internal receive path. Reception
starts when the LAN Connect component detects a valid frame on its receive differential pair.
When in Full Duplex mode, the ICH2 integrated LAN Controller also supports the IEEE 802.3x
flow control standard.
Table 5-3. EEPROM Word Field Descriptions
Bits
Name
Description
Word Ah
15:14
Signature
A signature of 01b indicates to the LAN Controller that there is a valid EEPROM
present. If this field is not equal to 01b, the other bits are ignored and the default
values are used.
Word Ah
13
ID
The ID bit indicates how the Subsystem ID and Subsystem Vendor ID fields are
used as described in
Section 7.1.14
. Default value is 0b.
Word Ah
12:11
Reserved
Should be set to 0b.
Word Ah
10:8
Revision ID
These three bits are used as the three least significant bits of the device revision, if
bits [15, 14, and 13] = 011b and the ID was set as described in
Section 7.1.14
. The
default value depends on the silicon revision.
Word Ah
7
Power
Management
Enables the LAN Controller’s PCI power management capabilities. This bit is
always set to 1.
Word Ah
6
Deep Power
Down
Bit is used as the Deep Power Down enable/disable bit. When the DPD bit = 0,
deep power down is enabled in the D3 power state while PME is disabled. If the
DPD bit = 1, deep power down is disabled in the D3 power state while PME is
disabled.
Word Ah
5
Wake on LAN
This bit sets the LAN Controller into WOL mode. When in this mode, the LAN
Controller reads three additional words from the EEPROM, word addresses 0h,
1h, and 2h. These words are expected to hold the MAC Individual Address. After
reading these words, the LAN Controller wakes the system by asserting PME#
when a wake-up packet is received. Default value is 0b.
Word Ah
4:3
Reserved
Should be set to 00b.
Word Ah
2
Reserved
Should be set to 00b.
Word Ah
1
Standby
Enable
Enables the LAN Controller to enter standby mode. When this bit = 1, the LAN
Controller is able to recognize an idle state and can enter standby mode (some
internal clocks are stopped for power saving purposes). If this bit = 0, the idle
recognition circuit is disabled and the LAN Controller always remains in an active
state.
Word Ah
0
Reserved
Should be set to 0.
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