Accelerated Graphics Port Interface Specification

AGP3.0 Interface Specification
Rev. 1.0
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Table 2: V2.0 Compatibility
AGP3.0 Feature Impact
Uses the same connector and signal pins as
AGP4x with a few additional signals to
support the new signaling.
Uses the same AGP 1.5 V and Universal AGP connectors
as AGP2.0.
Common Clock remains at 66 MHz. Same flow control and PCI speeds. Buffering needs for
Source Synchronous transfers double relative to AGP4X.
Same protocol and flow control as AGP. Maintains interface level backward compatibility.
Continued support for PCI master and target
transactions.
Allows the use of the existing PCI cores.
Same power delivery scheme as AGP and
AGP Pro.
Uses AGP 1.5 V and AGP Pro 1.5 V connectors as is.
Same device enumeration and configuration
schemes.
Backward compatible with the existing AGP enumeration
schemes.
Routing rules, board impedance requirements
etc. compatible with AGP.
Maintains evolutionary approach. Allows a motherboard
to support both AGP2.0 and AGP3.0 modes of operation.
1.5 Classification of Changes
Changes to AGP2.0 are classified as follows:
1. Performance Enhancements: Changes here target improving the performance of the interface.
2. Feature Removals: Changes here target removing unused features in AGP with the intention of
simplifying the interface.
3. Feature Additions or Enhancements: These target new usage models that were not the focus of
AGP. Almost all feature additions or enhancements are specific to workstation platforms and are
described in the Appendices.