Accelerated Graphics Port

related topics
{system, computer, user}
{game, team, player}

The Accelerated Graphics Port (often shortened to AGP) is a high-speed point-to-point channel for attaching a video card to a computer's motherboard, primarily to assist in the acceleration of 3D computer graphics. Since 2004, AGP has been progressively phased out in favor of PCI Express. As of mid-2009, PCIe cards dominate the market, but new AGP cards and motherboards are still available for purchase, though OEM driver support is minimal.[1]

Contents

Advantages over PCI

As computers became increasingly graphically oriented, successive generations of graphics adapters began to push the limits of PCI, a bus with shared bandwidth. This led to the development of AGP, a "bus" dedicated to graphics adapters.

The primary advantage of AGP over PCI is that it provides a dedicated pathway between the slot and the processor rather than sharing the PCI bus. In addition to a lack of contention for the bus, the point-to-point connection allows for higher clock speeds. AGP also uses sideband addressing, meaning that the address and data buses are separated so the entire packet does not need to be read to get addressing information. This is done by adding eight extra 8-bit buses which allow the graphics controller to issue new AGP requests and commands at the same time with other AGP data flowing via the main 32 address/data (AD) lines. This results in improved overall AGP data throughput.

In addition, to load a texture, a PCI graphics card must copy it from the system's RAM into the card's framebuffer, whereas an AGP card is capable of reading textures directly from system RAM using the Graphics Address Remapping Table (GART). GART reapportions main memory as needed for texture storage, allowing the graphics card to access them directly.[2] The maximum amount of system memory available to AGP is defined as the AGP aperture.

Full article ▸

related documents
Windows Me
Electronics
Audio Video Interleave
Hercules emulator
Amiga 500
Intelligent network
ISCSI
Apple Lisa
Intel 8085
XScale
LINC
AOL Instant Messenger
Windows 1.0
Slave clock
Digital audio
Dial-up internet access
Parallel port
PCX
DECnet
ARCNET
Intel 8051
Internet Protocol
Shortwave
Wearable computer
Game Boy line
Pocket PC
S/PDIF
Java Message Service
Phantom circuit
Wireless telegraphy