Chapter 4 System Support

4.2PCI BUS OVERVIEW

NOTE: This section describes the PCI bus in general and highlights bus implementation

in this particular system. For detailed information regarding PCI bus operation, refer to the PCI Local Bus Specification Revision 2.2.

These systems implement a 32-bit Peripheral Component Interconnect (PCI) bus (spec. 2.2) operating at 33 MHz. The PCI bus handles address/data transfers through the identification of devices and functions on the bus. A device is typically defined as a component or slot that resides on the PCI bus (although some components such as the MCH and ICH2 are organized as multiple devices). A function is defined as the end source or target of the bus transaction. A device may contain one or more functions.

In the standard configuration these systems use a hierarchy of three PCI buses (Figure 4-1). The PCI bus #0 is internal to the 815E chipset components and is not physically accessible. The AGP bus that services the AGP slot (or resident AGP controller on the Small Form Factor) is designated as PCI bus #1. All PCI slots and the NIC function internal to the 82801BA reside on PCI bus #2.

82845 MCH Component

 

Mem. Cntlr.

PCI

 

PCI Bus #1

Function

Bus #0

AGP

(AGP Bus)

 

 

Bridge

AGP Connector

Hub Link I/F

 

Function

 

 

 

Hub Link Bus

 

 

Hub Link I/F

 

 

82801BA ICH2 Component

 

 

 

PCI Bus #0

PCI Bridge

 

 

 

 

 

 

 

 

 

 

 

 

Function

 

 

 

EIDE

 

USB

 

SMBus

 

LPC

 

AC97

 

 

 

 

Controller

 

I/F

 

Controller

 

Bridge

 

Audio

PCI

 

 

 

Function

 

Function

 

Function

 

Function

 

Function

Bus #2

NIC

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

I/F

 

 

 

 

 

 

 

 

 

 

 

 

Function

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PCI

Bus #2

PCI Connector 1

PCI Connector 2

PCI Connector 3 [1]

PCI Connector 4 [2]

PCI Connector 5 [2]

NOTES:

[1]Desktop and Configurable minitower models only.

[2]Configurable minitower models only

4-2Compaq Evo and Workstation Personal Computers

Featuring the Intel Pentium 4 Processor

Second Edition – January 2003

Page 56
Image 56
Compaq W4000 manual PCI BUS Overview, Eide USB