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Intel
®
820E Chipset
R
102 Design Guide
Interrupts B, D, E, and H service devices internal to the ICH2. Interrupts A, C, F, and G are unused and
can be used by PCI slots. The following figure shows an example of IRQ line routing to the PCI slots.
Figure 63. Example PCI IRQ Routing
ICH2
PIRQA#
PIRQB#
PIRQC#
PIRQD#
PIRQE#
PIRQF#
PIRQG#
PIRQH#
INTA
INTB
INTC
INTD
INTA
INTB
INTC
INTD
INTA
INTB
INTC
INTD
INTA
INTB
INTC
INTD
PCI_IRQ_routing_ex
Slot 1
PCI Device 0
(AD16 to IDSEL)
Slot 2
PCI Device 5
(AD21 to IDSEL)
Slot 3
PCI Device 6
(AD22 to IDSEL)
Slot 4
PCI Device C
(AD28 to IDSEL)
The PCI IRQ routing in the previous figure allows the ICH2’s internal functions to have a dedicated
IRQ, assuming add-in cards are single-function devices and use INTA. If a P2P bridge card or a
multifunction device uses more than one INTn# pin on the ICH2 PCI bus, the ICH2’s internal functions
will start sharing IRQs.
Figure 63 is one example. It is up to board designers to route these signals most efficiently for their
particular systems. A PCI slot can be routed to share interrupts with any of the ICH2’s internal
device/functions.
2.22. LAN Layout Guidelines
The ICH2 provides several options for integrated LAN capability. The platform supports several
components, depending on the target market. These guidelines use the Intel 82562ET to refer to both the
Intel 82562ET and the Intel 82562EM. The Intel 82562EM is specified in those cases where there is a
difference.
LAN Connect Component Connection Features
Intel 82562EM Advanced 10/100 Ethernet AOL* & Ethernet 10/100 connection
Intel 82562ET 10/100 Ethernet Ethernet 10/100 connection
Intel 82562EH 1-Mbit HomePNA* LAN 1-Mbit HomePNA connection
Intel developed a dual footprint for the Intel 82562ET and Intel 82562EH components, to minimize the
required number of board builds. A single layout with the specified dual footprint allows the OEM to
install the LAN connect component appropriate for the market need. Design guidelines are provided for
each required interface and connection. Refer to Figure 64 and Table 22 for the corresponding section of
the design guide.