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Chapter 5 Input/Output Interfaces
5-32
Compaq iPAQ Series of Desktop Personal Computers
Second Edition – February 2001
5.9
NETWORK INTERFACE CONTROLLER
All Compaq iPAQ systems include a network interface controller (NIC) on the system board
supported by an RJ-45 connector with two LED indicators. The iPAQ 1.x system uses an 82559
Ethernet Controller component while the iPAQ 2.0 system uses equivalent logic integrated into the
ICH2 component. The following discussion applies to both systems, which are functionally the
same.
The NIC supports speeds of 10 and 100 Mbs in half- or full-duplex modes, and provides IEEE
802.3u auto-negotiation. 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.
Network Interface Controller Block Diagram
The Intel 825xx 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 825xx controller features high and low priority queues and provides priority-packet (Quality
of Service or “QOS”) 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. Identification, configuration
and connection parameters are held in an EEPROM.
RJ-45
Connector
TX/RX
825xx
Ethernet
Controller
PCI Bus
Active/
Link
(Green)
Speed
(Yellow)
25 MHz
Clock
Circuitry
EEP/
ROM
CLK
SMBus
82801 ICH
PHY
I/F
TX/RX
Содержание iPAQ 1.0
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