The feature connector was an internal connector found mostly in some older ISA,

VESA Local Bus The VESA Local Bus (usually abbreviated to VL-Bus or VLB) is a short-lived expansion bus introduced during the i486 generation of x86 IBM-compatible personal computers. Created by VESA (Video Electronics Standards Association), the VESA Local Bus ...

, and

PCI PCI may refer to: Business and economics * Payment card industry, businesses associated with debit, credit, and other payment cards ** Payment Card Industry Data Security Standard, a set of security requirements for credit card processors * Pro ...

graphics cards A graphics card (also called a video card, display card, graphics adapter, VGA card/VGA, video adapter, display adapter, or mistakenly GPU) is an expansion card which generates a feed of output images to a display device, such as a computer moni ...

, but also on some early AGP ones. It was intended for use by devices which needed to exchange large amounts of data with the

graphics card A graphics card (also called a video card, display card, graphics adapter, VGA card/VGA, video adapter, display adapter, or mistakenly GPU) is an expansion card which generates a feed of output images to a display device, such as a computer moni ...

without hogging a computer system's CPU or

data bus In computer architecture, a bus (shortened form of the Latin '' omnibus'', and historically also called data highway or databus) is a communication system that transfers data between components inside a computer, or between computers. This ex ...

, such as

TV tuner card A TV tuner card is a kind of television tuner that allows television signals to be received by a computer. Most TV tuners also function as video capture cards, allowing them to record television programs onto a hard disk much like the digital vi ...

video capture card Video capture is the process of converting an analog video signal—such as that produced by a video camera, DVD player, or television tuner—to digital video and sending it to local storage or to external circuitry. The resulting digital data a ...

s, MPEG video decoders (e.g. RealMagic), and first generation 3D graphic accelerator cards. Early examples include the IBM EGA video adapter. Several standards existed for feature connectors, depending on the bus and graphics card type. Most of them were simply an 8, 16 or 32-

bit The bit is the most basic unit of information in computing and digital communications. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represente ...

wide internal connector, transferring data between the graphics card and 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 MByte/s for a standard ISA-based

SVGA Super VGA (SVGA) is a broad term that covers a wide range of computer display standards that extended IBM's VGA Video Graphics Array (VGA) is a video display controller and accompanying de facto graphics standard, first introduced with the I ...

, up to 150 MByte/s for a VESA-based or PCI-based one, while the standard 16 bit ISA bus ran at ~5.3 MByte/s and the VESA bus at up to 160 MByte/s bandwidth. The Feature connector bandwidths were far beyond the capabilities of e.g. a 386, 486 and barely handled by an early

Pentium Pentium is a brand used for a series of x86 architecture-compatible microprocessors produced by Intel. The original Pentium processor from which the brand took its name was first released on March 22, 1993. After that, the Pentium II and Pe ...

. Depending on the implementation, it could be uni or bi-directional, and carry

analog Analog or analogue may refer to: Computing and electronics * Analog signal, in which information is encoded in a continuous variable ** Analog device, an apparatus that operates on analog signals *** Analog electronics, circuits which use analog ...

color information as well as data. Unlike analog overlay devices however, a feature connector carried mainly

data In the pursuit of knowledge, data (; ) is a collection of discrete values that convey information, describing quantity, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols that may be further interpreted ...

and essentially allowed an

expansion card In computing, an expansion card (also called an expansion board, adapter card, peripheral card or accessory card) is a printed circuit board that can be inserted into an electrical connector, or expansion slot (also referred to as a bus slo ...

to access the graphics card

Video RAM Dual-ported video RAM, or VRAM, is a dual-ported variant of dynamic RAM (DRAM), which was once commonly used to store the framebuffer in graphics adapters. Note that most computers and game consoles do not use this form of memory, and dual-porte ...

directly, although directing this data stream to the system's CPU and RAM was not always possible, limiting its usefulness mainly to display 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 resurfaced with the introduction of the

Scan-Line Interleave Scan-Line Interleave (SLI) from 3dfx is a method for linking two (or more) video cards or chips together to produce a single output. It is an application of parallel processing for computer graphics, meant to increase the processing power availa ...

(3dfx SLI) technology, although this technology is aimed at connecting two equally powered and complete graphic cards to produce a single, increased performance visual output, and not e.g. directly interfacing TV tuner cards.

PCMCIA card

A variant of that idea, born for

PCMCIA Card In computing, PC Card is a configuration for computer parallel communication peripheral interface, designed for laptop computers. Originally introduced as PCMCIA, the PC Card standard as well as its successors like CardBus were defined and develop ...

, is named Zoomed video port

References

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External links

Definition of VESA Advanced feature connection at thefreedictionary.comDefinition of VGA feature connection at thefreedictionary.com
an ATI extension of the Feature Connector Computer buses Display technology VESA