Accelerated Graphics Port Interface Specification

AGP3.0 Interface Specification
Rev. 1.0
5
Table of Contents
1 INTRODUCTION AND OVERVIEW .......................................................................11
1.1 Organization of This Document..................................................................................................11
1.2 Reference Documents ...............................................................................................................12
1.3 Need for AGP3.0.........................................................................................................................12
1.4 Evolutionary Aspects of AGP3.0.................................................................................................12
1.5 Classification of Changes...........................................................................................................13
1.5.1 Changes to AGP ..................................................................................................................14
2 DESCRIPTION OF NEW FEATURES....................................................................16
2.1 Signal Interface Differences........................................................................................................16
2.1.1 New and Redefined Signals.................................................................................................17
2.1.2 Clocking Changes................................................................................................................18
2.1.3 AGP3.0 Signaling Scheme...................................................................................................21
2.1.4 Calibration Cycle..................................................................................................................21
2.1.5 Dynamic Bus Inversion........................................................................................................27
2.2 Summary of Interfaces ...............................................................................................................29
2.2.1 IDSEL Usage for Configuration............................................................................................31
2.3 Transaction and Protocol Changes............................................................................................31
2.3.1 AGP Transaction Requests .................................................................................................31
2.3.2 Removal of Transaction Types............................................................................................32
2.3.3 Flow Control.........................................................................................................................34
2.3.4 Ordering Rule Changes .......................................................................................................36
2.4 Platform Architecture Differences ..............................................................................................38
2.4.1 Hardware Enforced Cache Coherency................................................................................38
2.4.2 AGP3.0/AGP2.0 Compatibility..............................................................................................39
2.4.3 Peer-to-Peer Access ...........................................................................................................42
2.5 AGP3.0 Programming.................................................................................................................43
2.6 Register Table Format................................................................................................................44
2.7 Required Master and Target Registers ......................................................................................45
2.7.1 PCISTS: PCI STATUS REGISTER .....................................................................................45
2.7.2 CAPPTR: CAPABILITIES POINTER....................................................................................45
2.7.3 NCAPID: AGP IDENTIFIER REGISTER..............................................................................46
2.7.4 AGPSTAT: AGP STATUS REGISTER ................................................................................47
2.7.5 AGP_CMD: AGP COMMAND REGISTER...........................................................................48
2.8 AGP3.0 Connector Pin-outs .......................................................................................................50
3 AGP3.0 PHYSICAL LAYER SPECIFICATION.........................................................51
3.1 Overview .....................................................................................................................................51
3.1.1 Introduction...........................................................................................................................51
3.1.2 AGP3.0 Signal Definitions ....................................................................................................51
3.2 Transfer Mode Operations..........................................................................................................54
3.2.1 AGP3.0 Common Clock Transfer Mode Operation.............................................................55
3.2.2 Source Synchronous Transfer Mode Operation..................................................................55
3.2.3 Sideband Strobe Synchronization........................................................................................60
3.3 Timing Definitions .......................................................................................................................60
3.3.1 Common Clock Operations .................................................................................................60
3.3.2 Source Synchronous Operation ..........................................................................................61
3.4 Interface Signaling.......................................................................................................................63