Concept in Definition ABC

Although sharing, in general, is good, in the science of computing This is not always the case, and a good example of this is the graphics cards; The big problem with the PCI bus is that by serving various types of peripherals, it creates bottlenecks that delay the delivery of information from the memory even the peripheral itself.

This makes PCI graphics cards ineffective for time consuming or graphics intensive applications. real, since the flow of graphical data can be easily interrupted by requests from other peripherals.

This is fatal for, for example, video games, since they require a constant flow and refresh of the graphics.

To avoid these problems, the

AGP bus (Accelerated Graphics Port), which directly and exclusively connects the graphics adapter of the system to the RAM memory.

It was developed by Intel in 1996 starting from the same PCI, since we remember that the problem was not technical, but rather of sharing this last bus for several tasks, which affects the performance of the graphics.

In each computer system (computer) there is only one AGP slot, the measurements of which differ from those PCI slots, in addition to their color, being that of the AGP slot brown, while the PCI ones are colored White.

This limits to a single card graph by computer system, although "tricks" have been made to skip the limitation that this single card could cause in some cases, like building a card with two video outputs.

These were usually VGA and DVI, so we could connect our computer to someone monitor, either through the most modern DVI connection, or - if the monitor was older and only had that port-, through the VGA connection, but it could also allow us to control two monitors simultaneously.

If we didn't have that option, we could always install a second graphics card through a PCI slot, so that we had two graphics cards in the system, each of them controlling a monitor different.

The AGP standard reached version 3.0, always evolving on a 66 MHz clock speed basis, but reducing the necessary voltage and increasing data transfer, so version 1.0 consumed 3.3 V and had a data rate of 266 MB / s, although the transfer was later doubled to 533 MB / s.

Version 2.0 consumed 1.5 V and quadrupled the velocity transfer rate reaching up to 1,066 MB / s. Finally, version 3.0 reduced the consumption up to 0.8 V while multiplying the transfer by eight, raising it to 2,133 MB / s.

Subsequently there have been several extensions to the standard, some of them unofficial,

As is the case with AGP Express. The official extensions have been the AGP Pro, for graphic cards of use professional, and 64-bit AGP (the original specification was for 32-bit systems), intended to equip the incipient 64-bit computers at that time.

Years have not passed by the AGP standard, and the natural substitute for the AGP port, which is already being abandoned, is the PCI-Epress (abbreviated as PCIe), which improves in speed to AGP, it is available in various sizes, and seeks to be a substitute for both the bus dedicated only to graphics, and for the more generic PCI.

Photos: Fotolia - Arthur Palmer / Jerome Salort

Topics in AGP