- Feature connector
It was intended for use by devices which needed to exchange large amounts of data with the
graphics cardwithout hogging a computer system's CPU or data bus, such as TV tuner cards, video capture cards, MPEG video decoders, first generation 3D graphic acceleratorcards and the such.
Several standard existed for "feature connectors", depending on the bus and graphics card type. Most of them were simply an 8, 16 or 32-
bitwide internal connector, transferring data from and to the graphics card to another device, bypassing the system's CPU and memory completely.
Their speeds often far exceeded the speed of normal ISA or even early PCI buses, (e.g. 40 MB/s for a standard ISA-based SVGA, up to 150 MB/s for a PCI or VESA-based one, while the ISA and VESA bus had much lower or barely as much bandwidth, with such figures being far beyond the capabilities of e.g. a 386, 486 or barely handled by an early
Depending on the implementation, it could be uni or bi-directional, and carry analog color information as well as data. Unlike analog overlay devices however, a feature connector carried mainly
dataand essentially allowed an expansion cardto access the graphics card Video RAMdirectly, although directing this data stream to the system's CPU and RAM was not always possible, limiting its usefulness mainly for displaying purposes.
Although its use rapidly declined after the introduction of the faster AGP internal bus, it was, at its time, the only feasible way to connect certain types of graphics-intensive devices to an average computing system without exceeding the available CPU power and memory bandwidth, and without the disadvantages and limitations of a purely analog overlay.
The idea of accessing a video card's memory directly has recently resurfaced with the introduction of the
Scalable Link Interface(SLI) technology by NVidia, although this technology is aimed at connecting two equally powered and complete graphic cards in order to produce a single, increased performance visual output, and not e.g. directly interfacing TV tuner cards.
* [http://computing-dictionary.thefreedictionary.com/VESA+Advanced+Feature+Connector Definition of VESA Advanced feature connection at thefreedictionary.com]
* [http://computing-dictionary.thefreedictionary.com/VGA%20feature%20connector Definition of VGA feature connection at thefreedictionary.com]
* [http://web.archive.org/web/20050210035518/http://www.ati.com/support/faq/amcvip.html AMC] , an ATI extension of the Feature Connector
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