Technical Reference Guide
Compaq Personal Computers
Changed - June 1998 D-3
TX Data
TX/RX
Filters
D.2.2 CARD POWER AND CLOCK
The controller ca r d includes on-board p ower l ogic that receives +5 VDC p ower fr om the PCI
connector or the WOL h ea der. The PCI CLK sign al provides the clock sour ce for the controller
when the system is up and active. When the system is off or in Standby the on-board clock
generator provides the clock signal.
NOTE: Lack of a WOL header connection with the main system will result in the
controller board n ot receiving power at an y time. Therefore the WOL header cable
should always be installed even if Wake-On-LAN functionality is not required.
D.2.3 82558 CONTROLLER
The Intel 82558 Fast Ethernet LAN controller provides most of the functionality of the card
(Figure D-3). The 82558 provides the following features:
Dual-mode support with auto-switching between 10BASE-T to 100BASE-TX PHY.
Digitally controlled adaptive equalization of transmission
Optimized PCI bandwidth with enhanced support of PCI commands.
ACPI support of power-down and wake-up states.
Wake On LAN (WOL) support.
LANDesk Service Agent (LSA) support.
Figure D-3 shows the internal architecture of the 82558 Ethernet controller.
Figure D–3. 82558 Controller Internal Architecture
The 82558 controller features auto-negotiation of both speed and direction (half/full duplex). The
82558 provides high-level command support for minimum Host CPU intervention and uses 3-KB
FIFOs for both transmit and receive buffers.
82558 Ethernet Controller
Bus
I/F
3-KB
TX FIFO
10BASE-TX/
100BASE-T
PHY
AD31..0
PCI Bus
RX Data
Micro
Machine FIFO Cntrl
3-KB
RX FIFO
4-Ch
DMA
Cntlr.