functions and type of computer cards
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Function and types of
Computer cardsComputer cards are devices which are used to connect peripheral components.They are a printed circuit board used to accomplish a specific task.
These types of cards can be connected to a computer in two ways:
Using the PCI slots on a motherboard
This is a typical interface used mostly. If the on-
board card fails to work, it is possible to plug anew card on the PCI slot and continue your work.
This is one of the advantages of having PCI slotson a motherboard.
Built-in on a motherboard
Current computer already have all the main cardsintegrated with the main board, no need to buy additional cards. Unless for
better performance specially if you are in video gaming and graphical
applications.
Several kinds of cards can be fitted on a computer. Modern computerincorporates at leastgraphics, sound and network cards on the main board means they are built with the motherboard.
Internal modem and TV cards are the other types of cards which can be hookedon PCI slot.
Types of PC cards
Graphics card enables to display images and videos on screen
Sound card enables to play music on a computer
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Network card allows computers to communicate each other
Modem card used to connect to a telephone line to get dialup internet service
How Sound Cards Work
Computer Hardware Image Gallery
A sound card allows a computer to create and record real, high-quality sound. See morecomputer hardwarepictures.
Photo courtesyHowStuffWorks Shopper
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Before the invention of the sound card, aPCcould make one sound - a beep. Although the computer
could change the beep's frequency and duration, it couldn't change the volume or create other sounds.
At first, the beep acted primarily as a signal or a warning. Later, developers created music for the earliest
PC games using beeps of different pitches and lengths. This music was not particularly realistic -- you can
hear samples from some of these soundtracks atCrossfire Designs.
Fortunately, computers' sound capabilities increased greatly in the 1980s, when several manufacturers
introduced add-on cards dedicated to controllingsound. Now, a computer with a sound card can do far
more than just beep. It can produce 3-D audio for games or surround sound playback forDVDs. It can
also capture and record sound from external sources.
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In this article, you'll learn how a sound card allows a computer to create and record real, high-quality
sound.4. See more
A sound card must translate between sound waves andbits and bytes.
Analog vs. Digital
Sounds and computer data are fundamentally different. Sounds are analog - they are made of waves that
travel through matter. People hear sounds when these waves physically vibrate theireardrums.
Computers, however, communicate digitally, using electrical impulses that represent 0s and 1s. Like a
graphics card, a sound card translates between a computer's digital information and the outside world's
analog information.
Sound is made of waves that travel through a medium, such as air or water.
The most basic sound card is a printed circuit board that uses four components to translateanalogand digitalinformation:
An analog-to-digital converter (ADC)
A digital-to-analog converter (DAC)
An ISA or PCI interface to connect the card to themotherboard
Input and output connections for a microphone andspeakers
Instead of separate ADCs and DACs, some sound cards use a coder/decoder chip, also called
a CODEC, which performs both functions.
In the next section, we'll explore the analog-to-digital and digital-to-analog conversions that take
place on the sound card.
X-FI
One of the newest advances in sound card technology is , or Xtreme Fidelity, from SoundBlaster
manufacturerCreative. features:
"Active Modal Architecture," which gives people different sound options for games, leisure use or music
creation
A Digital Signal Processor (DSP) with 51 million transistors
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Multiple processing engines, each of which performs specific sound operations
A 24-bit Crystallizer, which reverses some of the sound quality loss inherent in 16-bitCDrecording
4. See more
An analog-to-digital converter measures sound waves at frequent intervals.
ADCs and DACs
Imagine using yourcomputerto record yourself talking. First, you speak into amicrophonethat you have
plugged into your sound card. The ADC translates the analog waves of your voice into digital data that
the computer can understand. To do this, it samples, or digitizes, the sound by taking precise
measurements of the wave at frequent intervals.
The number of measurements per second, called the sampling rate, is measured in kHz. The faster a
card'ssampling rate, the more accurate its reconstructed wave is.
If you were to play your recording back through thespeakers, the DAC would perform the same basic
steps in reverse. With accurate measurements and a fast sampling rate, the restored analog signal can
be nearly identical to the original sound wave.
Even high sampling rates, however, cause some reduction in sound quality. The physical process of
moving sound through wires can also cause distortion. Manufacturers use two measurements to
describe this reduction in sound quality:
Total Harmonic Distortion (THD), expressed as a percentage
Signal to Noise Ratio (SNR), measured in decibels
For both THD and SNR, smaller values indicate better quality. Some cards also support digital input,
allowing people to store digital recordings without converting them to an analog format.
Next, we'll look at the other components commonly found on sound cards and what they do.
METHODS OF SOUND CREATION
Computers and sound cards can use several methods to create sounds. One is frequency
modulation (FM) synthesis, in which the computer overlaps multiple sound waves to make more complex
wave shapes. Another is wave table synthesis, which uses samples of real instruments to replicate
musical sounds. Wave table synthesis often uses several samples of the same instrument played at
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different pitches to provide more realistic sounds. In general, wave table synthesis creates more accurate
reproductions of sound than FM synthesis.
4. See more
A PCI sound card
Other Sound Card Components
In addition to the basic components needed for sound processing, many sound cards include additional
hardware or input/output connections, including:
Digital Signal Processor (DSP): Like a graphics processing unit (GPU), a DSP is a
specializedmicroprocessor. It takes some of the workload off of the computer's CPU by performing
calculations for analog and digital conversion. DSPs can process multiple sounds, or channels,
simultaneously. Sound cards that do not have their own DSP use the CPU for processing. Memory: As
with agraphics card, a sound card can use its ownmemoryto provide faster data processing. Input and
Output Connections: Most sound cards have, at the very minimum, connections for
amicrophoneandspeakers. Some include so many input and output connections that they have
abreakout box, which often mounts in one of the drive bays, to house them. These connections include:
Multiple speaker connections for 3-D andsurround sound
Sony/Philips Digital Interface (S/PDIF), a file transfer protocol for audio data. It uses either coaxial or
optical connections for input to and output from the sound card.
Musical Instrument Digital Interface (MIDI), used to connect synthesizers or other electronic instrumentsto their computers.
FireWireandUSBconnections, which connect digital audio or video recorders to the sound card
Game designers use 3-D sound to provide fast-paced, dynamic sound that changes based on a player's
position in the game. In addition to using sound from different directions, this technology allows realistic
recreations of sound traveling around or through obstacles.Surround soundalso uses sound from
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several directions, but the sound does not change based on the listener's actions. Surround sound is
common inhome theatersystems.
Like agraphics card, a sound card uses software to help it communicate with applications and with the
rest of the computer. This software includes the card's drivers, which allow the card to communicate with
theoperating system. It also includes application program interfaces (APIs), which are sets of rules orstandards that make it easier for software to communicate with the card. The most common APIs include:
Microsoft: DirectSound
Creative: Environmental Audio Extensions (EAX) and Open AL
Sensaura: MacroFX
QSound Labs: QSo
Next, we'll look at integratedmotherboardand external sound control options.
3-D VS SURROUND SOUND AND DRIVERS & APIS
Game designers use 3-D sound to provide fast-paced, dynamic sound that changes based on a player's
position in the game. In addition to using sound from different directions, this technology allows realistic
recreations of sound traveling around or through obstacles.Surround soundalso uses sound from
several directions, but the sound does not change based on the listener's actions. Surround sound is
common inhome theatersystems.
Like agraphics card, a sound card uses software to help it communicate with applications and with the
rest of the computer. This software includes the card's drivers, which allow the card to communicate with
theoperating system. It also includes application program interfaces (APIs), which are sets of rules or
standards that make it easier for software to communicate with the card. The most common APIs include:
Microsoft: DirectSound
Creative: Environmental Audio Extensions (EAX) and Open AL
Sensaura: MacroFX
QSound Labs: QSound
4. See more
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External sound controller
Photo courtesyHowStuffWorks Shopper
Other Options for Sound Control
Not every computer has a sound card. Some motherboards feature integrated audio support instead.
Amotherboardthat has its own DSP can process multiple data streams. It may also support 3-D positional
and Dolbysurround sound. However, in spite of these features, most reviewers agree that separate
sound cards provide better audio quality.
Laptops usually have integrated sound capabilities on their motherboards or small sound cards. However,
space and temperature control considerations make top-of-the-line internal cards impractical.So,laptopusers can purchase external sound controllers, which useUSBorFireWireconnections. These
external modules can significantly improve laptop sound quality.
For more information on sound cards and related topics, check out the links on the following page.
SHOPPING FOR A SOUND CARD
Numerous factors affect a sound card's abilities to provide clear, high-quality sound. When shopping for a
sound card, pay attention to:
ADC and DAC data capacity, measured inbits
Signal-to-noise ratio (SNR) and total harmonic distortion (THD)
Frequency response, or how loudly the card can play sounds at different frequencies
Sampling rate
Output channels, such as 5.1 or 7.1 surround sound
Supported application programming interfaces (APIs)
Certifications, including Dolby Master and THX
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Anyone investing in a top-of-the-line sound card should also have high-qualityspeakers. Even the best
sound card cannot compensate for poor speaker quality.
How Graphics Cards Work4. See all Hardware Basics articles
Computer Hardware Image Gallery
Graphics cards take data from the CPU and turn it into pictures. See more computer hardware pictures.
The images you see on yourmonitorare made of tiny dots called pixels. At most common resolution
settings, a screen displays over a million pixels, and the computer has to decide what to do with every
one in order to create an image. To do this, it needs a translator -- something to takebinary datafrom
theCPUand turn it into a picture you can see. Unless a computer has graphics capability built intothemotherboard, that translation takes place on the graphics card.
A graphics card's job is complex, but its principles and components are easy to understand. In this article,
we will look at the basic parts of a video card and what they do. We'll also examine the factors that work
together to make a fast, efficient graphics card.
Think of a computer as a company with its own art department. When people in the company want a
piece of artwork, they send a request to the art department. The art department decides how to create the
image and then puts it on paper. The end result is that someone's idea becomes an actual, viewable
picture.
A graphics card works along the same principles. TheCPU, working in conjunction with software
applications, sends information about the image to the graphics card. The graphics card decides how to
use the pixels on the screen to create the image. It then sends that information to themonitorthrough a
cable.
Creating an image out ofbinary datais a demanding process. To make a3-Dimage, the graphics card
first creates a wire frame out of straight lines. Then, it rasterizes the image (fills in the remaining pixels).
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It also addslighting, texture and color. For fast-paced games, the computer has to go through this
process about sixty times per second. Without a graphics card to perform the necessary calculations, the
workload would be too much for the computer to handle.
The graphics card accomplishes this task using four main components:
Amotherboardconnection for data and power
Aprocessorto decide what to do with each pixel on the screen
Memoryto hold information about each pixel and to temporarily store completed pictures
Amonitorconnection so you can see the final result
Next, we'll look at the processor and memory in more detail.
4. See all Hardware Basics articles
Graphics cards take data from the CPU and turn it into pictures. Find out the parts of a graphics card and readexpert reviews of graphics cards.
2008 HowStuffWorks
The GPU
Like amotherboard, a graphics card is a printed circuit board that houses aprocessorandRAM. It also
has an input/output system(BIOS)chip, which stores the card's settings and performs diagnostics on
thememory, input and output at startup. A graphics card's processor, called agraphics processing
unit (GPU), is similar to a computer's CPU. A GPU, however, is designed specifically for performing the
complex mathematical and geometric calculations that are necessary for graphics rendering. Some of the
fastest GPUs have more transistors than the average CPU. A GPU produces a lot of heat, so it is usually
located under a heat sink or a fan.
In addition to its processing power, a GPU uses special programming to help it analyze and use
data. ATIand nVidia produce the vast majority of GPUs on the market, and both companies have
developed their own enhancements for GPU performance. To improve image quality, the processors use:
Full scene anti aliasing (FSAA), which smoothes the edges of 3-D objects
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Anisotropic filtering (AF), which makes images look crisper
Each company has also developed specific techniques to help the GPU apply colors, shading, textures
and patterns.
As the GPU creates images, it needs somewhere to hold information and completed pictures. It uses thecard'sRAMfor this purpose, storing data about each pixel, its color and its location on the screen. Part of
the RAM can also act as a frame buffer, meaning that it holds completed images until it is time to display
them. Typically, video RAM operates at very high speeds and is dual ported, meaning that the system
can read from it and write to it at the same time.
The RAM connects directly to the digital-to-analog converter, called the DAC. This converter, also
called the RAMDAC, translates the image into an analog signal that the monitor can use. Some cards
have multiple RAMDACs, which can improve performance and support more than one monitor. You can
learn more about this process inHow Analog and Digital Recording Works.
The RAMDAC sends the final picture to the monitor through a cable. We'll look at this connection andother interfaces in the next section.
THE EVOLUTION OF GRAPHICS CARDS
Graphics cards have come a long way since IBM introduced the first one in 1981. Called aMonochrome
Display Adapter (MDA), the card provided text-only displays of green or white text on a black screen.
Now, the minimum standard for new video cards is Video Graphics Array (VGA), which allows 256
colors. With high-performance standards like Quantum Extended Graphics Array (QXGA), video cards
can display millions of colors at resolutions of up to 2040 x 1536 pixels.
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This Radeon X800XL graphics card has DVI, VGA and ViVo connections.
PCI Connection
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Graphics cards connect to the computer through the motherboard. Themotherboardsupplies power to
the card and lets it communicate with theCPU. Newer graphics cards often require more power than the
motherboard can provide, so they also have a direct connection to the computer's power supply.
Connections to the motherboard are usually through one of three interfaces:
Peripheral component interconnect(PCI)
Advanced graphics port(AGP)
PCI Express(PCIe)
PCI Express is the newest of the three and provides the fastest transfer rates between the graphics card
and the motherboard. PCIe also supports the use of two graphics cards in the same computer.
Most graphics cards have two monitor connections. Often, one is a DVI connector, which
supportsLCDscreens, and the other is a VGA connector, which supportsCRTscreens. Some graphics
cards have two DVI connectors instead. But that doesn't rule out using a CRT screen; CRT screens can
connect to DVI ports through an adapter. At one time, Apple made monitors that used the proprietaryApple Display Connector (ADC). Although these monitors are still in use, new Apple monitors use a DVI
connection.
Most people use only one of their two monitor connections. People who need to use two monitors can
purchase a graphics card with dual head capability, which splits the display between the two screens. A
computer with two dual head, PCIe-enabled video cards could theoretically support four monitors.
In addition to connections for the motherboard and monitor, some graphics cards have connections for:
TV display: TV-out or S-video
Analog video cameras: ViVo or video in/video out
Digital cameras:FireWireorUSB
Some cards also incorporate TV tuners. Next, we'll look at how to choose a good graphics card.
DIRECTX AND OPEN GL
DirectX and Open GL are application programming interfaces, or APIs. An API helps hardware and
software communicate more efficiently by providing instructions for complex tasks, like 3-D rendering.
Developers optimize graphics-intensive games for specific APIs. This is why the newest games often
require updated versions of DirectX or Open GL to work correctly.
APIs are different from drivers, which are programs that allow hardware to communicate with a
computer'soperating system. But as with updated APIs, updated device drivers can help programs run
correctly.
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Some cards, like the ATI All-in-Wonder, include connections for televisions and video as well as a TV tuner.
Photo courtesy ofHowStuffWorks Shopper
Choosing a Good Graphics Card
A top-of-the-line graphics card is easy to spot. It has lots ofmemoryand a fastprocessor. Often, it's also
more visually appealing than anything else that's intended to go inside a computer's case. Lots of high-
performance video cards are illustrated or have decorative fans or heat sinks.
But a high-end card provides more power than most people really need. People who use their computers
primarily fore-mail, word processing or Web surfing can find all the necessary graphics support on
amotherboardwith integrated graphics. A mid-range card is sufficient for most casual gamers. People
who need the power of a high-end card include gaming enthusiasts and people who do lots of 3-D
graphic work.
A good overall measurement of a card's performance is its frame rate, measured in frames per second
(FPS). The frame rate describes how many complete images the card can display per second. The
human eye can process about 25 frames every second, but fast-action games require a frame rate of at
least 60 FPS to provide smooth animation and scrolling. Components of the frame rate are:
Triangles or vertices per second:3-Dimages are made of triangles, or polygons. This measurement
describes how quickly the GPU can calculate the whole polygon or the vertices that define it. In general, it
describes how quickly the card builds a wire frame image.
Pixel fill rate: This measurement describes how many pixels the GPU can process in a second, which
translates to how quickly it can rasterize the image.
The graphics card's hardware directly affects its speed. These are the hardware specifications that most
affect the card's speed and the units in which they are measured:
GPU clock speed (MHz)
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Size of the memory bus (bits)
Amount of available memory (MB)
Memory clock rate (MHz)
Memory bandwidth (GB/s)
RAMDAC speed (MHz)
The computer'sCPUandmotherboardalso play a part, since a very fast graphics card can't compensate
for a motherboard's inability to deliver data quickly. Similarly, the card's connection to the motherboard
and the speed at which it can get instructions from the CPU affect its performance.
For more information on graphics cards and related topics, check out the links on the following page.
INTEGRATED GRAPHICS AND OVERLOCKING
Manymotherboardshave integrated graphics capabilities and function without a separate graphics card.
These motherboards handle 2-D images easily, so they are ideal for productivity and Internet
applications. Plugging a separate graphics card into one of these motherboards overrides the onboard
graphics functions.
Some people choose to improve their graphics card's performance by manually setting their clock speed
to a higher rate, known as overclockings. People usually overclock theirmemory, since overclocking the
GPU can lead to overheating. While overclocking can lead to better performance, it also voids the
manufacturer's warranty.
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