AGP(Accelerated Graphics Port)

 

AGP(Accelerated Graphics Port)

       i.          AGP (Accelerated Graphics Port): A connection type designed for attaching a graphics card to a computer to speed up 3D graphics.

      ii.          Created by Intel in 1997: It was designed to improve the performance of graphics, especially for 3D gaming and multimedia.

    iii.          Improvement over PCI: AGP is faster and better suited for graphics than the older PCI standard, which wasn't optimized for heavy graphics tasks.

    iv.          Direct Memory Access: AGP allows the graphics card to directly access the computer’s memory, making it faster to load and display textures.

      v.          Higher Bandwidth: AGP offers more bandwidth than PCI(Peripheral Component Interconnect), allowing the graphics card to transfer data faster, which helps in rendering 3D graphics smoothly.

    vi.          By the mid-2000s, PCI Express replaced AGP as the standard for connecting graphics cards. PCIe offered higher speeds, more lanes, and could support multiple devices on the same bus, while AGP was limited to one graphics card.

 

2. Purpose of AGP

AGP was built to offer better performance for 3D graphics than the older PCI bus. The PCI(Peripheral Component Interconnect) bus was shared by various components like sound cards, network cards, and other peripherals, which limited the amount of data that could be processed for graphics. AGP provided a dedicated pathway between the graphics card and the CPU (Central Processing Unit) and RAM (Random Access Memory), allowing for faster data transfers and smoother graphics.

3. Key Features of AGP

AGP came with several features that made it superior to PCI for graphics processing:

• Direct Access to System Memory: AGP allowed the graphics card to access the system's main memory directly. This was useful for storing large textures and 3D models without needing a lot of memory on the graphics card itself.
• Pipelining: AGP could send multiple data requests without waiting for each previous request to finish. This made the flow of data much more efficient and faster compared to PCI(Peripheral Component Interconnect), which handled data requests one at a time.
• Sideband Addressing: This feature allowed AGP to send extra information (like addresses) along with the main data, speeding up communication between the graphics card and the system.
• Increased Bandwidth(the maximum amount of data that can be transmitted over a network or communication channel in a given amount of time): AGP offered a significantly higher bandwidth than PCI, which meant it could transfer much larger amounts of data in a shorter period. This was critical for processing the complex graphics needed in modern games and software.

4. AGP Versions and Speed

AGP evolved through different versions, with each new version offering faster data transfer speeds and improved functionality:

• AGP 1.0 (1x, 2x): This was the original version. AGP 1x operated at a base clock speed of 66 MHz, with a bandwidth of 266 MB/s. AGP 2x doubled this speed to 533 MB/s.
• AGP 2.0 (4x): This version improved the bandwidth even more, reaching speeds of 1.07 GB/s.
• AGP 3.0 (8x): The final and fastest version, which could transfer data at a rate of 2.1 GB/s. It operated at 533 MHz and could handle the large textures and high-resolution models needed in modern 3D graphics.

5. Architecture of AGP

AGP uses a point-to-point connection, meaning it has a direct link between the graphics card and the memory controller hub on the motherboard. This is different from PCI, where multiple devices share the same bus, leading to slower data transfer rates.

• AGP Slot: The slot on the motherboard where the graphics card connects looks similar to a PCI slot but is slightly different in design and placement.
• Modes of Operation:
• 1x mode: Basic mode, transfers data once per clock cycle.
• 2x mode: Doubles the transfer rate by sending data twice per cycle.
• 4x and 8x modes: Quadruple and octuple the transfer rates for faster graphics processing.

 

 

6. Difference between AGP and PCI

Parameters of Comparison	AGP	PCI
Definition	Hardware developed with high-speed direct point channels for 3D accelerators and video cards.	Hardware completely based on the ISA and VL-bus technology.
Abbreviation	Accelerated Graphic Port	Peripheral Component Interconnect
Introduced In	1996	1992
Purpose	Used alongside the graphic card	I/O interface bus
Priority Queues	Maybe high/low	Absent
3D Graphics quality	High	Low
Requests	Pipelined	Non-pipelined
Peripheral Device	High	Low
Address/Data	De-Multiplexed	Multiplexed
Slots	Short	Long
Target	Single	Multiple
Peak at 32 bits	533 Mb/s	133 Mb/s