FW21555AA Просмотр технического описания (PDF) - Intel

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FW21555AA

Non-Transparent PCI-to-PCI Bridge

Intel 

21555AA/BA and 21555AB/BB Differences

1.0

Introduction

This document defines the differences between the 21555AA/BA bridge when compared with the

21555AB/BB bridge. The 21555 bridge is a second generation Non-Transparent PCI-to-PCI

bridge.

1.1

Changes to the 21555 Bridge

After the introduction of the 21555AA/BA bridge, two errata were discovered

• The I2O circuitry would not work in asynchronous mode.

• The BSDL circuitry was driving data one cycle late.

Additionally, the PCI standards committee ratified the new PCI 2.3 Specification, which required

an additional bit to be added to the control register and status register.

The new 21555AB/BB bridge version addresses all three of these issues.

Note:

This Differences document is not a stand-alone document and does not provide complete 21555

bridge details. The intent here is only to highlight the feature differences between the

21555AA/BA and the 21555BA/BB steppings. Please be sure to review the data sheet and spec

updates for more complete information on the device.

2.0

Stepping Differences

Table 1. Stepping Differences

Package Markings

REV_ID

Register

Valuea

Speed (MHz)

Intel FW21555AA

Intel FW21555BA

Intel FW21555AB

Intel FW21555BB

02h

33

02h

66

03h

33

03h

66

a. Identified in a PCI system by reading the value in the REV_ID register.

Stepping

A2

A2

A3

A3

3.0

I2O Asynchronous Operation

The 21555AA/BA devices would not operate asynchronously. This behavior has been corrected in

the 21555AB/BB device. Please refer to the device data sheet for information on I2O operation.

Application Note

5

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