Other Platform Components; I/O & Firmware Bridge (Ifb); Programmable Interrupt Device (Pid); Reference Documents - Intel 460GX Software Developer’s Manual

Introduction
•
I2C Slave Interface will allow viewing and modifying of specific error and configuration
registers.
1.7

Other Platform Components

These 460GX devices provide access to flash space, interrupt collection and legacy features.
1.7.1 I/O & Firmware Bridge (IFB)
The 460GX chipset is designed to work with the IFB south bridge. As part of this support, the PXB
includes an internal PCI arbiter as well as support for an external PCI arbiter. The IFB consists of
an 8259C Interrupt controller, a bus-mastering IDE interface, and a Universal Serial Bus interface.
Devices using IFB are limited to a 32 bit addressing space available for DMA, not the full 44 bits
supported by the Itanium™ processor.
1.7.2

Programmable Interrupt Device (PID)

The PID is a PCI device that gathers interrupts and delivers them from the PCI bus to the system
bus using the SAPIC interrupt protocol. The interrupt will be presented to one of the processors on
the bus for servicing. A 460GX chipset based platform requires at least one PID located on the
compatibility PCI bus. The compatibility PID will handshake with the IFB before delivering a
south bridge/compatibility device interrupt. The same PID may also be used to deliver some
portion of the PCI based interrupts.
The system implementor can choose how many PIDs are used in the platform. If enough interrupt
lines are shared, there need be only one PID in the system; all interrupts in the system would then
be routed to that PID. Each PID has enough interrupt inputs to handle dedicated interrupts from the
cards on two PCI buses. Therefore, using one PID per PXB provides a high performance solution
with minimum routing between PCI buses.
1.8

Reference Documents

In addition to this document, the reader should be familiar with the following reference documents:
•
Intel® 460GX Chipset Datasheet
(Document Number: 248703)
•
Intel® Itanium™ Processor Hardware Developer's Manual
(Document Number: 248701)
•
Intel® Itanium™ Processor at 800 MHz and 733 MHz Datasheet
(Document Number: 245481)
•
Intel® 82460GX Chipset OLGA1 Package, Manufacturing, Mechanical, and Thermal Design
Guide
•
PCI Local Bus Specification, Rev 2.2
(http://www.pcisig.com/)
•
Accelerated Graphics Port Interface Specification
(http://www.intel.com/technology/agp/agp_index.htm)
1-6 Intel® 460GX Chipset Software Developer's Manual