Intel® 820E Chipset
R
22 Design Guide
Function Disable
The ICH2 provides the ability to disable the following functions: AC’97 Modem, AC’97 Audio, IDE,
USB or SMBus. Once disabled, these functions no longer d ecode I/O, memory or PCI configuration
space. Also, no interrupts or power management events are generated by the disabled functions.
Intruder Detect
The ICH2 provides an input signal (INTRUDER#) that can be attached to a switch that is activated when
the system case is opened. The ICH2 can be programmed to generate an SMI# or TCO interrupt resulting
from an active INTRUDER# signal.
SMBus
The ICH2 integrates an SMBus controller. The SMBus provides an interface to manage peripherals such
as serial presence detection (SPD) on RIMMs and thermal sensors. The slave interface allows an external
microcontroller to access system resources.
The Intel 820E chipset platform integrates several functions designed to expand the capability of
interfacing several components to the system.
Interrupt Controller
The interrupt capabilities of the Intel 820E chipset platform expands support for up to eight PCI interrupt
pins and PCI 2.2 message-based interrupts. In addition, the ICH2 supports system bus interrupt delivery.
FWH Flash BIOS
The Intel 820E chipset-based system platform supports firmware hub BIOS memory sizes up to 8 MB,
for increased system flexibility.
Alert on LAN*
The ICH2 supports Alert on LAN. In response to a TCO event (intruder detect, thermal event, processor
not booting), the ICH2 sends a message over ALERTCLK and ALERTDATA to alert the network
manager.