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Chapter 5 Input/Output Interfaces
5-32 Compaq iPAQ Family of Internet Devices
First Edition – March 2000
5.9 NETWORK INTERFACE CONTROLLER
The Compaq iPAQ includes a network interface controller (NIC) resident on the system board.
The NIC (Figure 5-14) includes the 82559 controller, two LED indicators, and support firmware.
The support firmware is contained in the system (BIOS) ROM. The NIC can operate in half- or
full-duplex modes, and provides auto-negotiation of both mode and speed. Half-duplex operation
features an Intel-proprietary collision reduction mechanism while full-duplex operation follows
the IEEE 802.3x flow control specification. Transmit and receive FIFOs of 3 kilobytes each
reduce the chance of overrun while waiting for bus access.
LED Function
Green Activity/Link: Indicates network activity and link pulse
reception.
Yellow Speed: Indicates link detection in 100 MB/s mode
(always on if 100Base-Tx is forced).
Figure 5-14.
10/100 TX Network Interface Controller Block Diagram
The Intel 82559 Fast Ethernet Controller includes the following features:
♦
Intel 82559 Fast Ethernet controller with 32-bit architecture and 3-KB TX/RX buffers.
♦
Dual-mode support with auto-switching between 10BASE-T and 100BASE-TX.
♦
Power down and Wake up support in both APM and ACPI environments (PME- and WOL).
♦
Alert-on-LAN (AOL v1.0) support.
♦
Dual control (PCI and SM bus interfaces).
♦
Link and Activity LED indicator drivers
The 82559 controller features high and low priority queues and provides priority-packet
processing for networks that can support that feature. The controller’s micro-machine processes
transmit and receive frames independently and concurrently. Receive runt (under-sized) frames
are not passed on as faulty data but discarded by the controller, which also directly handles such
errors as collision detection or data under-run. An EEPROM, accessed by the 82559 controller
over a serial interface, is used to store identification, configuration and connection parameters.
The NIC uses 3.3 VDC auxiliary power, which allows the 82559 controller to support Wake-On-
LAN (WOL) and Alert-On-LAN (AOL) functions while the main system is powered down.
RJ-45
Connector
TX/RX
82559
Ethernet
Controller
PCI Bus #1
Active/
Link
(
Green
)
Speed
(
Yellow
)
25 MHz
Clock
Circuitry
EEP/
ROM
CLK
SMBus
82801 ICH