82801DB Datasheet, PDF (34/587 Pages) Intel Corporation – Intel 82801DB I/O Controller Hub 4 (ICH4)

Introduction
Manageability
The ICH4 integrates several functions designed to manage the system and lower the total cost of
ownership (TC0) of the system. These system management functions are designed to report errors,
diagnose the system, and recover from system lockups without the aid of an external
microcontroller.
• TCO Timer. The ICH4’s integrated programmable TCO Timer is used to detect system locks.
The first expiration of the timer generates an SMI# that the system can use to recover from a
software lock. The second expiration of the timer causes a system reset to recover from a
hardware lock.
• Processor Present Indicator. The ICH4 looks for the processor to fetch the first instruction
after reset. If the processor does not fetch the first instruction, the ICH4 will reboot the system.
• ECC Error Reporting. When detecting an ECC error, the host controller has the ability to
send one of several messages to the ICH4. The host controller can instruct the ICH4 to
generate either an SMI#, NMI, SERR#, or TCO interrupt.
• Function Disable. The ICH4 provides the ability to disable the following functions: AC ’97
Modem, AC ’97 Audio, IDE, LAN, USB, or SMBus. Once disabled, these functions no longer
decode I/O, memory, or PCI configuration space. Also, no interrupts or power management
events are generated from the disable functions.
• Intruder Detect. The ICH4 provides an input signal (INTRUDER#) that can be attached to a
switch that is activated by the system case being opened. The ICH4 can be programmed to
generate an SMI# or TCO interrupt due to an active INTRUDER# signal.
• SMBus 2.0. The ICH4 integrates an SMBus controller that provides an interface to manage
peripherals (e.g., serial presence detection (SPD) and thermal sensors) with host notify
capabilities.
• Alert On LAN*. The ICH4 supports Alert On LAN and Alert On LAN 2. In response to a
TCO event (intruder detect, thermal event, processor not booting) the ICH4 sends a message
over the SMBus. A LAN controller can decode this SMBus message and send a message over
the network to alert the network manager.
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Intel^® 82801DB ICH4 Datasheet