8
Chipset
The Intel 440GX+ chipset is the latest generation of Intel’s PCI set and is designed
for the Pentium III processors. It consists of the Intel 82440GX PCI/A.G.P. controller
(PAC) and the Intel 82371EB PCI/ISA/IDE controller (PIIX4e) bridge chip.
Intel 82440GX PCI/A.G.P. Controller (PAC)
The 82440GX host bridge is a 492-pin BGA device with a 3.3V core and mixed 5V,
3.3V, and GTL+ signal interface pins. The PCI host bridge in the 440GX provides the
sole pathway between processor and I/O systems, performing control signal
translations and managing the data path in transactions with PCI resources onboard.
This includes translation of 64-bit operations in the GTL+ signaling environment at
100MHz, to a 32-bit PCI Rev. 2.1 compliant, 5V signaling environment at 33MHz.
The 440GX also handles arbitration for PCI bus master access. Although the 440GX
is capable of being clocked to operate with multiple processor FSB frequencies, on
the host bridge only supports a 100MHz FSB. The device also features 32-
bit addressing (not 36-bit), 4 or 1 deep in-order and request queue (IOQ), dynamic
deferred transaction support, and Desktop Optimized (DTO) GTL bus driver support
(gated transceivers for reduced power operation). The PCI interface provides greater
than 100 MB/s data streamlining for PCI to SDRAM accesses (120 MB/s for writes),
while supporting concurrent processor host bus and PCI transactions to main
memory. This is accomplished using extensive data buffering, with processor-to-
SDRAM and PCI-to-SDRAM write data buffering and write-combining support for
processor-to-PCI burst writes.
Intel 82371EB PCI ISA IDE controller (PIIX4e)
The PIIX4e is a multi-function PCI device, providing four PCI functions in a single
package: PCI-to-ISA bridge, PCI IDE interface, PCI USB controller, and power
management controller. Each function within the PIIX4e has its own set of
configuration registers and once configured, each appears to the system as a distinct
hardware controller sharing the same PCI bus interface. The PIIX4e is packaged as
a 324-pin BGA device. On , its primary role is to provide the gateway to all
PC-compatible I/O devices and features.
uses the following PIIX4e features:
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PCI interface
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ISA bus interface
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Dual IDE interfaces
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USB interface
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Power management control
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System reset control
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ISA-compatible interrupt control
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PC-compatible timer/counters and DMA controllers
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Baseboard plug-n-play support
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General purpose I/O
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Real-time Clock and CMOS configuration RAM.
