Introduction; About This Design Guide - VIA Technologies Apollo Pro133A Design Manual

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Technologies, Inc.

Design Guide - VT82C694X Apollo Pro133 with VT82C686A

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NTRODUCTION

This document provides design guidelines for motherboard manufacturers on developing single Slot-1 or Socket-370 processor

and Apollo Pro133A (VT82C694X) based systems. All the major underlying subsystems, especially Host Interface and Memory

subsystems, related to the motherboard design are described in detail. General layouts, routing guidelines and power requirements

of each subsystem are presented.

A brief description of each chapter is given below:

Chapter 1: Introduction.

An overview of Apollo Pro133A reference design features is given in this chapter along with general recommendations on

Pro133A system design.

Chapter 2: Motherboard Design Guidelines.

General design schemes and recommended layout rules are shown in chapter 2. It begins with the 510-pin BGA ballout

assignment. The following sections contain placement and routing of a motherboard, PCB stack-up information and power

requirements for a desktop or a mobile system. Detailed placement, layout, and routing guidelines for each bus or subsystem

(Host bus, Memory subsystem, AGP bus and PCI bus) are described in section 2.4.

Chapter 3: Timing Diagram Analysis.

133 MHz timing analyses for memory read/write cycles are discussed in Chapter 3.

Chapter 4: Electrical Specifications.

The electrical specifications for the VT82C694X North Bridge are listed in this chapter.

Chapter 5: Signal Connectivity and Design Checklist.

The final chapter provides signal connection tables as a brief reference for hardware design engineers who are experienced in PC

motherboard design. Also design checklists are included that can be used for reviewing Pro133A system designs.

Appendices: Reference Design Schematics.

Appendix A shows two power-up strapping circuits for the VT82C686A SPKR pin which determines the function of the

Secondary IDE disk data bus pins (SDD[15..0]) to be either SDD[15..0] (SPKR strapped low) or Audio/Game port functions

(SPKR strapped high).

Appendix B describes the Printed Circuit Board (PCB) layout recommendations for VIA VT1611A (AC'97 audio codec) and

Game/MIDI port in a motherboard design.

Reference schematics for an Apollo Pro133A system design with VT82C686A South Bridge are shown in Appendix C.

Preliminary Revision 0.5, November 19, 1999

Introduction

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