2-4 Service Guide
Enhanced Power Management
PIIX4’s power management functions include enhanced clock control, local and global monitoring
support for 14 individual devices, and various low-power (suspend) states, such as Power-On
Suspend, Suspend-to-DRAM, and Suspend-to-Disk. A hardware-based thermal management circuit
permits software-independent entrance to low-power states. PIIX4 has dedicated pins to monitor
various external events (e.g., interfaces to a notebook lid, suspend/resume button, battery low
indicators, etc.). PIIX4 contains full support for the Advanced Configuration and Power Interface
(ACPI) Specification.
System Management Bus (SMBus)
PIIX4 contains an SMBus Host interface that allows the CPU to communicate with SMBus slaves
and an SMBus Slave interface that allows external masters to activate power management events.
Configurability
PIIX4 provides a wide range of system configuration options. This includes full 16-bit I/O decode on
internal modules, dynamic disable on all the internal modules, various peripheral decode options,
and many options on system configuration.
2.2.1 Features
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Supported Kits for Pentium
®
II Microprocessors
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82440BX ISA/DP Kit
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Multifunction PCI to ISA Bridge
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Supports PCI at 30 MHz and 33 MHz
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Supports PCI Rev 2.1 Specification
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Supports Full ISA or Extended I/O (EIO) Bus
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Supports Full Positive Decode or Subtractive Decode of PCI
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Supports ISA and EIO at 1/4 of PCI Frequency
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Supports both Mobile and Desktop Deep Green Environments
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3.3V Operation with 5V Tolerant Buffers
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Ultra-low Power for Mobile Environments Support
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Power-On Suspend, Suspend to RAM, Suspend to Disk, and Soft-OFF System States
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All Registers Readable and Restorable for Proper Resume from 0.V Suspend
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Power Management Logic
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Global and Local Device Management
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Suspend and Resume Logic
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Supports Thermal Alarm
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Support for External Microcontroller
