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MoboCop · 10-06-2004 · Category: Tech-planations

AGP


The Accelerated Graphics Port (AGP or A.G.P.) is a high performance, component level interconnect targeted at 3D graphical display applications. AGP is based on a set of performance extensions or enhancements to the PCI bus.

The AGP interface specification uses the 66 MHz PCI (PCI Local Bus Specification) specification as an operational baseline, and provides four significant performance extensions or enhancements to the PCI specification which are intended to optimize the AGP for high performance 3D graphics applications.

AGP neither replaces nor diminishes the necessity of PCI in the system. This high speed port (AGP) is physically, logically, and electrically independent of the PCI bus. It is intended for the exclusive use of visual display devices; all other I/O devices will remain on the PCI bus. The add-in slot defined for AGP uses a new connector body (for electrical signaling reasons) which is not compatible with the PCI connector; PCI and AGP boards are not mechanically interchangeable.

The AGP interface specification was developed by Intel.

AGP 1.0

Modes

  • 1x (266Mbps) (8 bytes per two clock cycles)
  • 2x (533Mbps) (8 bytes per clock cycle)

Connectors

  • AGP 3.3v keyed

AGP 2.0

AGP 2.0 Specification (PDF file)

Modes

  • 1x (266Mbps) (8 bytes per two clock cycles)
  • 2x (533Mbps) (8 bytes per clock cycle)
  • 4x (1.07Gbps) (16 bytes per clock cycle)

Connectors

  • AGP 3.3v keyed
  • AGP 1.5v keyed
  • AGP UNIVERSAL (supports both 3.3v and 1.5v cards)

AGP Pro

AGP Pro, is primarily designed to deliver additional electrical power to the graphics add-in cards to meet the needs of advanced workstation graphics. AGP Pro will accept AGP 1.0 and 2.0 cards depending on the connector used on the motherboard.

AGP Pro 1.0 Specification (PDF file)

AGP Pro 1.1a Specification (PDF file)

Modes

  • 1x (266Mbps) (8 bytes per two clock cycles)
  • 2x (533Mbps) (8 bytes per clock cycle)
  • 4x (1.07Gbps) (16 bytes per clock cycle)

Connectors

  • AGP Pro 3.3v keyed
  • AGP Pro 1.5v keyed
  • AGP Pro UNIVERSAL (supports both 3.3v and 1.5v cards)

AGP 3.0 (Draft)

AGP3.0 offers a significant increase in performance along with feature enhancements to AGP2.0. This interface represents the natural evolution from the existing AGP to meet the ever-increasing demands placed on the graphic interfaces within the workstation and desktop environments.

AGP Pro 3.0 Draft (PDF file)

Modes

  • 1x (266Mbps) (8 bytes per two clock cycles)
  • 2x (533Mbps) (8 bytes per clock cycle)
  • 4x (1.07Gbps) (16 bytes per clock cycle)
  • 8x (2.1Gbps) (32 bytes per clock cycle)

Connectors

  • AGP 1.5v keyed
  • AGP Pro 1.5v keyed

While AGP 3.0 spec uses existing AGP 2.0 and AGP Pro 1.5v connectors, this does not mean you can use an AGP 3.0 card on a AGP 2.0 motherboard, you cannot. What is does mean is that some AGP 3.0 motherboards will accept AGP 2.0 1.5v cards. It depends on the design of the motherboard. Some AGP 3.0 motherboards will support only AGP 3.0 and some will support both AGP 2.0 and AGP 3.0. Since this is still a draft spec any of the info on AGP 3.0 is subject to change.

Contents

  1. Introduction
  2. VESA Local Bus
  3. PCI
  4. AGP
  5. PCI Express

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