VESA Feature Connector
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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 Bu ...
, 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 * Prov ...
graphics cards A graphics card (also called a video card, display card, graphics accelerator, graphics adapter, VGA card/VGA, video adapter, display adapter, or colloquially GPU) is a computer expansion card that generates a feed of graphics output to a displa ...
, but also on some early AGP ones. It was intended for use by devices that needed to exchange large amounts of data with the
graphics card A graphics card (also called a video card, display card, graphics accelerator, graphics adapter, VGA card/VGA, video adapter, display adapter, or colloquially GPU) is a computer expansion card that generates a feed of graphics output to a displa ...
without hogging a computer system's
CPU A central processing unit (CPU), also called a central processor, main processor, or just processor, is the primary processor in a given computer. Its electronic circuitry executes instructions of a computer program, such as arithmetic, log ...
or
data bus In computer architecture, a bus (historically also called a data highway or databus) is a communication system that transfers data between components inside a computer or between computers. It encompasses both hardware (e.g., wires, optical ...
, 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 ...
s, video capture cards, MPEG video decoders (e.g. SGS Thomson MPEG Decoder), 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 communication. 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 represented as ...
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 MB/s for a standard ISA-based
SVGA Super VGA (SVGA) or Extended VGA is a broad term that covers a wide range of computer display standards that extended IBM's Video Graphics Array, VGA specification. When used as shorthand for a resolution, as VGA and XGA often are, SVGA refers to ...
, up to 150 MB/s for a VESA-based or PCI-based one, while the standard 16 bit ISA bus ran at ~5.3 MB/s and the VESA bus at up to 160 MB/s bandwidth. The feature connector bandwidths were far beyond the capabilities of e.g. a
386 __NOTOC__ Year 386 (Roman numerals, CCCLXXXVI) was a common year starting on Thursday of the Julian calendar. At the time, it was known as the Year of the Consulship of Honorius and Euodius (or, less frequently, year 1139 ''Ab urbe condita''). ...
, 486 and barely handled by an early
Pentium Pentium is a series of x86 architecture-compatible microprocessors produced by Intel from 1993 to 2023. The Pentium (original), original Pentium was Intel's fifth generation processor, succeeding the i486; Pentium was Intel's flagship proce ...
. 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 Data ( , ) are a collection of discrete or continuous values that convey information, describing the quantity, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols that may be further interpreted for ...
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 sl ...
to access the graphics card
Video RAM Video random-access memory (VRAM) is dedicated computer memory used to store the pixels and other graphics data as a framebuffer to be rendered on a computer monitor. It often uses a different technology than other computer memory, in order to b ...
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) is a multi-GPU method developed by 3DFX for linking two (or more) video cards or chips together to produce a single output. It is an application of parallel computing, parallel processing for computer graphics, meant t ...
(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 PC Card is a technical standard specifying an expansion card interface for laptops and PDAs. The PCMCIA originally introduced the 16-bit ISA-based PCMCIA Card in 1990, but renamed it to PC Card in March 1995 to avoid confusion with the name of ...
, 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