Parts of Computer-CPU

8/14/2019 Parts of Computer-CPU

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PARTS OF COMPUTER

CENTRAL PROCESSING UNIT

In order to work, a computer needs some sort of brain or calculator

At the core of every computer is a device roughly the size of a large

postage stamp. This device is known as the central processing unit,

or CPU for short. This is the brain of the computer. It reads and

executes program instructions, performs calculations, and makes

decisions. The CPU is responsible for storing and retrieving

information on disks and other media. It also handles information from

one part of the computer to another like a central switching station

that directs the flow of traffic throughout the computer to another like

a central switching station that directs the flow of traffic thought the

computer to another like a central switching station that directs the

flow of traffic thought the computer system.

PCs are designed around different CPU generations. Intel is not the

only company manufacturing CPUs but by far the leading one. The

following table shows the different CPU generations. They are

predominantly Intel chips, but in the 5 the generation we see

alternatives. There are CPUs of many brand names (IBM, Texas,

Cyrix, AMD), and often they make models which overlap two

generations. This can make it difficult to keep track of CPUs here is

an attempt to identify the various CPUs according to generation.


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The following table helps you to understand the differences between

the different processors that Intel has introduced over the years.

Name Date Transistors

Microns

ClockSpeed

Datewidth

MIPS

8080 1974 6,000 6 2MHz 8 bits 0.64

8088 1979 29,000 3 5MHz 16bits,8bit bus

0.33

80286 1982 134,000 1.5 6MHz 16 bits 1

80386 1985 275,000 1.5 16MHz 32 bits 5

80486 1989 1,200,000 1 25MHz 32 bits 20Pentium 1993 3,100,000 0.8 60MHz 32 bits,64 bitbus

100

PentiumII

1997 7,500,000 0.35 233MHz

32 bits,64 bitbus

300

PentiumIII

1999 9,500,000 0.25 450MHz 32 bits,64 bitbus

510

Pentium4

2000 42,000,000 0.18 1.5 GHz 32 bits,64 bitbus

1,700


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WHAT DOES THE CPU DO?

The CPU carries out instructions and tells the rest of the computer

system what to do. This is done by the Control Unit of the CPU whichsends command signals to the other components of the system.

It also performs arithmetic calculations and date manipulation.

E.g. Comparisons sorting, combining, etc. This is performed by

a part of the CPU known as the Arithmetic Logic Unit.

It holds date and instructions which are in current use. These

are kept in the main store or Memory.

An actual CPU has these components or other with different names

that provide the same functions.

Control Unit: - The control unit directs the entire computer system to

carry out stored program instructions. The control unit mustcommunicate with both the arithmetic logic unit and main memory.

The control unit uses the instruction contained in the instruction

register to decide which circuits need to be activated.

The control unit co-ordinates the activates of

the other two units as well as all peripheral and

auxiliary storage devices linked to the computer.

The control unit instructs the arithmetic logic unit

which arithmetic operations or logical operation is to

be performed.

Specialized electronic circuitry in the control

unit is designed to decode program instructions held

Instruction

Register

Program

Counter

+ 1


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in the main memory. Each instruction is read from

the memory into the instruction register. The

process of reading an instruction is often referred to

as the fetch-execute process.

Arithmetic Logic Unit: - The

Arithmetic logic unit executes

arithmetic and logical operations.

Arithmetic operations include addition,

subtraction, multiplication and division

Logical operations compare numbers,

letters and special characters.

Comparison operations test for three conditions:-

Equal-to condition in which two values are the same

Less-than condition in which one value is smaller than the

other

Greater-than condition in which one value is larger than the

other

Relational operations (=, 0 are used to describe the

comparison operations used by the arithmetic logic unit.

The arithmetic logic unit performs logic functions such as AND, OR

and Not. The accumulator is used to accumulate results. It is the

place where the answers from many operations are stored

Accumulator

General-

Purpose

Re ister


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temporarily before being put out to the operations are to performed by

the arithmetic logic unit.

Memory Unit: -The Memory unit is the part of the computer that

holds data and instructions for processing. Although it is closely

associated with the CPU, in actual fact is separate from it. Memory

associated with the CPU is also called primary storage, primary

memory, main storage, internal storage and main memory. When we

load software from a floppy disk, hard disk or CD-ROM, it is stored in

the Main Memory.

When you think about it, its amazing how many different types of

electronic memory you encounter in daily life. Many of them have

become an integral part of our vocabulary : RAM, ROM, Cache,

Dynamic RAM, Static RAM, Flash memory, Memory sticks, Volatile

memory, Virtual memory, Video memory, BIOS.

You already know that the computer in front of you has memory.

What you may not know is that most of he electronic items you use

every day have some form of memory also. Here are just a few

examples of the many items that use memory : Computers, Cell

phones, Personal Digital Assistants (PDSs) Game consoles, car

radios, VCRs, TVs.

Each of these devices uses different types of memory in different

ways!


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TYPES OF MEMORY

There are two basic types of computer memory inside the computer,

RAM and ROM.

(a) RAM : RAM stand for Random Access Memory.

This is really the main store and is the place where the programs and

software we load gets stored. When the Central Processing Unit runs

a program, it fetches the program instructions from the RAM and

carries them out.

It the Central Processing Unit needs to store the results of

calculations, it can store them in RAM.

Random Access Memory can have instructions READ from it by the

CPU and also it can have numbers or other computer date WRITTEN

to it by the CPU. When we switch a computer off, whatever is stored

in the RAM gets erased.

Random access memory (RAM) is best known form of computer

memory. RAM is considered random access because you can

access any memory cell directly if you know the row and column that

interest at that cell. The opposite of RAM is serial access memory

(SAM). (SAM) stores date as a series of memory cells that can only

be accessed sequentially (like a cassette tape). If the data is foundSAM works very well for memory buffers, where the data is normally

stored in the order in which it will be used (a good example is the

texture buffer memory on a video Card). RAM data, on the other

hand, can be accessed in any order.


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(b) ROM : ROM stands for Read Only Memory.

The CPU can only fetch or read instructions from Read Only Memory

(or ROM). ROM comes with instructions permanently stored inside

and these instructions cannot be over-written by the computers CPU.

ROM memory is used for storing special sets of instructions which the

computers needs when it starts up.

When we switch the computer off, the contents of the ROM do not

get erased but remain stored permanently. Therefore it is non-volatile.

Read-only memory (ROM), also known as firmware is anintegrated circuit programmed with specific data when it is

manufactured. ROM chips are used not only in computers, but in

most other electronic items as well.

(c) Cache Memory : Caching is a technology based on the

memory subsystem of your computer. The main purpose of a

cache is to accelerate your computer while keeping the price of

the computer low. Caching allows you to do your computer

tasks more rapidly.

Cache technology is use of a faster but smaller memory type to

accelerate a slower but larger memory type. When using a cache,

you must check the cache to see if an item is in there. If it is there, its

called a cache hit. If not, it is called a cache miss and the computer

must wait for a round trip from the larger, slower memory area. A

cache has some maximum size that is much smaller than the larger

storage area. It is possible to have multiple layers of cache.

There are a lot of subsystems in a computer; you can put cache

between many of them to improve performance. Heres an example.

We have the microprocessor (the fastest thing in the computer). Then


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theres the L1 cache that caches the L2 cache that caches the main

memory which can be used (and is after used) as a cache for even

slowed peripherals like hard disks and CD ROMs the hard disks are

also used to cache an even slower medium your internet connection.

L1 cache-memory accesses at full microprocessor speed (10

nanoseconds, 4 kilobytes to 16 kilobytes in size)

L2 cache Memory access of type SRAM (around 20 to 30

nanoseconds, 128 kilobytes to 512 kilobytes in size)

Min memory- Memory access of type RAM (around 60

nanoseconds, 32 megabytes to 128 megabytes in size)

Hard disk Mechanical-slow (around 12 milliseconds, 1

gigabyte to 10 gigabytes in size)

(d) Flash Memory: Electronic memory comes in a variety of forms

to serve a variety of purposes. Flash memory is used for easy and

fast information storage in such devices as digital cameras and home

video game consoles. It is used more as a hard drive than as RAM. In

fact, Flash memory is considered a solid state storage device. Solid

state means that there are no moving parts everything is electronic

instead of mechanical.

Here are a few examples of Flash memory:

Computers BIOS chip

Compact Flash (Most often found in digital cameras)

Smart Media (most often found in digital cameras)

Memory Stick( most often found in digital cameras)


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PCMCIA Type I and Type II memory cards (used as solid-state

disks in laptops)

Memory cards for video game consoles

Virtual Memory

Most computers today have something like 32 or 64 megabytes of

RAM available for the CPU to use. Unfortunately, that amount of RAM

is not enough to run all of the programs that most users expect to run

at once. For example, if you load the operating system, an e-mail

program a web browser and word processor into RAM

simultaneously, 32 megabytes is not enough to hold it all. If there

were no such thing as virtual memory, then once you filled up the

available RAM your computer would have to say Sorry, you cannot

load any more applications.

Please close another application to load a new one with virtual

memory, what the computer can do is look at RAM for areas that

have not been used recently and copy them onto the hard disk. This

frees up space in RAM to load the new application.

Because this copying happens automatically, you dont even

know it is happening and it makes your computer feel like that it has

unlimited RAM space even though it only has 32 megabytes installed.

Because hard disk space is so much cheaper than RAM chips, it also

has a once economic benefit.

The read/write speed of a hard drive is much slower than RAM and

the technology of a hard drive is not geared toward accessing small

pieces of data at a time. If your system has to rely too heavily on

virtual memory, you will notice a significant performance drop. The


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key is to have enough RAM to handle everything you tend to work on

simulating eusol then, the only time you feel the slowness of virtual

memory is when theres a slight pause when youre changing tasks.

When thats the case, virtual memory is perfect.

When it is not the case, the operating system has to constantly swap

information back and forth between RAM and the hard disk. This is

called thrashing, and it can make your computer feel incredibly slow.

The area of the hard disk that stores the RAM image is called a

page file. It holds pages of RAM on the hard disk, and the operatingsystem moves date back and forth between the page file and RAM.

On a Windows machine, page files have a SWP extension.

Cache

Level 1

Level 2

RAM

Physical

RAM

Virtual

Memory

Storage Device Types

RAM

Bids

Remova

l Drives

Network

internet

Nard

Opera

Input Sources

Keyboar

dMouse Remova

l Midis

Scann

er

Remot

e

Other

Source

CPURegister


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BUS

Buses have grown and evolved over the years in an effort to match

the performance of all the other computer components. Even so, the

evolution of the bus has been surprisingly slow compared to other

technologies. Most computers sold today still gave an IndustryStandard Architecture (ISA) bus that will accept computer cards

developed for the original IBM PC in the early 1980s.

There have been a couple of key reasons for this bus

longevity:

There is a need for long-term compatibility with a large number

of hardware manufactures. Before

the rise of multimedia, few hardware

peripherals fully utilized the speed of the

bus. A typical computer has two key

buses. The first one known as the

system bus or local bus connects themicroprocessor (central processing unit)

and the system memory. Other buses,

such as the ISA and PCI buses connect

to the system bus through a bridge,

which is a part of the computers chipset

and acts as a traffic cop, integrating the

CPU

Level

2

Memory

Controlle

RAM

Front side

AGP

Chipset

Graphic

s Card


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date from the other buses to the system

bus.

As the speed of central processing units (CPUs) and RAM increased,

it became more important to isolate the path between processor and

memory. A replacement for the standard system bus, called Dual

independent Bus (DIB), was created. DIB replaced the single system

bus with a front side bus and a backside bus. The backside bus has

one purpose: to provide a direct, fast channel between the CPU and

the Level 2 cache. The front side bus connected the system memory,

via the memory controller, to the CPU, and the other buses to the

CPU and system memory.

The other main bus, the shared bus, is for connecting additional

components to the computer. It is called a shared bus because it lets

multiple devices access the same path to the CPU and system

memory. This device includes such items such as:

Modem

Hard drive

Sound card

Graphics card

Controller card

Scanner

As technology advanced and the ISA bus grew long in the tooth,

other buses were developed. Key among these was Extended

Industry Standard architecture (EISA) which was 32 bits at 8 MHzand VESA Local Bus (VL Bus). The cool thing about VL-bus (named


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after VESA, the Video Electronics Standards association which

created the standard) is that it was 32 bits wide and operated at the

speed of the local bus, which was normally the speed of the

processor itself. The VL-bus essentially tied directly into the CPU.

This worked okay for a single device, or maybe even two. But

connecting more than two devices to the VL-bus introduced the

possibility of interference with the performance of the CPU. Because

of this the VL-Bus was typically used only for connecting a graphics

card, a component the really benefits from high speed access to the

CPU.

During the early 1990s Intel introduced a new bus standard for

consideration the peripheral Component Interconnect (PCI). PCI

presents a hybrid of sorts between ISA and VL-Bus. It provides direct

access to system memory for connected devices, but uses a bridge to

connect to the front side bus and therefore to the CPU. Basically this

means that it is capable of even higher performance than VL-Bus

while eliminating the potential for interference with the CPU.

PCI can connect more devices than VL-Bus up to five external

components. Each of the five connectors for an external component

can be replaced with two fixed devices on the motherboard. Also, you

can have more than one PCI bus on the same computer, although

this is rarely done. The PCI bridge chip regulates the speed of the

PCI bus independently of the CPUs speed. This provides a higher

degree of reliability and ensures that PCI-hardware manufactures

know exactly what to design for.

Bus Type Bus Width Bus Speed Mb/SEC

ISA 16 Bits 8 MHz 16 MBps

EISA 32 Bits 8 MHz 32 MBpsVL-BUS 32 Bits 25 MHz 100 MBps


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VL-BUS 32 Bits 33 MHz 132 MBps

PCI 32 Bits 33 MHz 132 MBps

PCI 64 Bits 33 MHz 264 MBps

PCI 64 Bits 66 MHz 512 Mbps

PCI 64 Bits 133MHz 1 GBps

PCI originally operated at 33 MHz using a 32 bit wide path.

Revisions to the standard include increasing the speed from 33 MHz

to 66 MHz and doubling the bit count to 64. Currently, PCI-X provides

for 64 bit transfers at a speed of 133 MHz for an amazing 1-GBps

(gigabyte per second) transfer rate!


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ADD-ON CARDS

ACCELERATED Graphics Port:

Modern computers rely heavily on graphic. For example, you

must be getting your training on a computer whose operating system

is based on a graphical user interface (GUI) that serves as the

primary interface between user and computer. You may enjoy playing

video games or creating 3-D graphics and animations. In fact, if you

are using your computer for anything other than the most basic

business-oriented tasks (word processing, spreadsheets) you

probably use lots of graphics.

The graphics card in modern PC can connect in one of several

different ways

Onboard The graphics chips and memory are built right onto

the motherboard.

PCI- The graphics card plugs into the PCI bus.

AGP The graphics card plugs into a slot dedicated to graphics

use.

Like virtually all other components in a computer, gr4aphics cards

prior to AGP relied on bus to connect to the control processing unit

(CPU) essentially, a bus is the channel or path between thecomponents in a computer. While AGP is based on the PCI bus and


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is after referred to as the AGP bus it is not actually a bus system.

Instead, it is a point-to point connection. In other words, the only

device connecting through AGP and system memory is the graphics

card. There are no other stops to make on the path. Therefore, it is

not truly a bus.

AGP provides two major enhancements over PCI:

Faster performance

Direct access to system memory

Lets look at exactly how AGP works so we can understand what

these enhancements mean.

AGP uses several techniques to achieve faster performance:

AGP is a 32 bit bus with a clock rate of 66 megahertz (MHz, or

million cycles per second). This means that in one second. It

can transfer 32 bits (4 bytes) of date 66 million times. The

transfer rate increases when you go to 2 x and 4x mode (more

about modes in this section).

There are not other devices on the AGP bus, which means that

the graphics card does not have to share the bus. The graphics

card is always able to operate at the maximum capacity of the

connection.

AGP uses pipelining to increases speed. Pipelining organizes

date retrieval into a sort of assembly line process. The graphics

card receives multiple chunks of date in response to a single

request.


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Think of pipelining as placing an order for a seven course

dinner : you can tell the waiter the first thing that you want, wait

for him to bring it, then tell him the next thing you want wait for

him to bring to and so on unit youre done with your order. Or

you can tell the waiter everything you want at once and let him

start bringing it to you. Youll get the courses in the same

sequence either way, but its much more efficient without the

additional discussions.

AGP uses sideband addressing, which allows the graphic card

to request and issue addressing information using eight

additional address lines that are separate from the 32 bit path

used to transfer date.

A good analogy for sideband addressing is the request line at a

radio station. Consider the music that the station is playing as date

flowing from system memory to the graphics card. You call in to the

stations request line and ask for a song to be played next. Your

request does not interfere with the current song that is playing but it

does tell the station what should be queued next. Sideband

addressing essentially does the same thing for AGP.

PCI VGA Bus

The original PC bus operated at 4.77 MHz and was 8 bits wide

meaning it could process 8 bits of date in each cycle. In 1982, it

improved to 16 bits at 8 MHz and officially became known as industry

standard Architecture (ISA). This bus design is capable of passing

along date at a rate of up to 16 MBps.


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Early graphics cards from the monochrome display adapter of

the early 1980 s through Super Video Graphics Array (SVGA)

adapters in the 1990 plugged into an ISA slot on the motherboard ofthe computer. As the number of colors and resolution of the display

increased, ISA-based graphics cards were simply too slow. The ISA

bus could not pump the image date to the CPU fast enough.

Over the years, ISA based graphics cards were replaced with

VESA Local Bus (VL-Bus) graphics cards. The Video ElectronicsStandards Association VESA agreed on a standard implementation of

SVGA that provided up to 16.8 million colors and 1280x1024

resolutions. These cards plugged into a special slot on the

motherboard that was on a separate bus from ISA. The graphics bus

was considered a local bus because it was connected directly to the

CPU and had to be physically near it.

The VL-bus was 32 bits wide and operated at the speed of the

local bus which was normally the speed of the processor itself. The

VL-Bus essentially tied directly into the CPU. This worked okay for a

single device, or maybe even two. But connecting more than two

devices to the VL-bus introduced the possibility of interference with

the performance of the CPU. Because of this the VL-Bus was

typically used only for connecting a graphics card, a component that

really benefits from high-speed access to the CPU.

VL-Bus cards communicated with the CPU at the same speed

as the CPUs clock. What this means is that if a CPU were rated at


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100 MHz the graphics card transferred 32 bits of date 100 million time

s per second. There were two problems with this approach:

The graphics card manufacturer has no idea how fast a

customers system would be.

Tying directly into the CPU could actually slow the CPU

down, resulting in poorer performance.

Along comes peripheral component interconnect (PCI) a

completely new Bus standard. The PCI bus is something of a hybrid

between ISA and VL-Bus it provides direct access to system memory

for connected devices but uses a bridge to connect to the CPU.

Basically, this means that it is capable of even higher performance

that VL Bus while eliminating the potential for interference with the

CPU.

Now AGP provides higher performance graphics processing

than PCI. With even more improvements in the queue for AGP, it

looks like graphics technology will continue to keep up with graphic

designers, meaning the coolest computer images are yet to come.

MOTHERBOARD & EXPANSION SLOTS

The motherboard has been an integral part of most personal

computers for more than 20 years. Think of a motherboard as a scale

model of a futuristic city with many modular plug-in buildings, each

using power from a common electrical system. Multiple-lane

highways of various circuit cards performing various functions all plug


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into many similar sockets on a common circuit board. Each circuit

card performs a unique function in the computer and gets it s power

from the socket.

The original IBM PC contained the original PC motherboard. In

this design which premiered in 1982.

Premiered in 1982 the motherboard itself was a large printed circuit

card that contained the 8088 microprocessor, the BIOS, sockets for

the CPUs RAM and a collection of slots that auxiliary cards could

plug into. If you wanted to add a floppy disk drive or a parallel port ofa joystick, you bought a separate card and plugged it into one of the

slots. This approach was pioneered in the mass market by the Apple

II machine. By making it easy to add cards, Apple and IBM

accomplished two huge things:

They made it easy to add new features to the machine over

time

They opened the computer to creative opportunities of third

party vendors.

Different motherboards of different vintages typically have different

from factors. The form factor is essentially the size shape and design

of the actual motherboard. There are more than a half dozen formfactors for motherboards. The motherboard by enabling pluggable

components allows users to personalize a computer system

depending on their applications and needs.

Motherboard: A motherboard is a multi layered printed circuit

board. Copper circuit paths called traces that resemble a complicated

roadmap carry signals and voltages across the motherboard. Layered


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fabrication techniques are used so that some layers of a board can

carry data for the BIOS, processor and memory buses while other

layers carry voltage and ground returns without the paths short-

circuiting at intersections. The insulated layers are manufactured into

one complete, complex sandwich. Chips and sockets are soldered

onto the motherboard.

Examples: the MSI 694D Pro AR supports dual Pentium

microprocessors has five PCI slots and a communications network

riser (CNR) slot. The board supports 133 MHz bus speeds and ultra

direct memory access 100 (UDMA). There are four USB ports and

onboard audio in the ATX from factor board.

Data Bus width: Modern Pentium class motherboards have a data

bus with 64 bits. That is the width of the date highway that goes in

and out of the processor. The Pentium processors, however, do use

32 bits registers to handle 32 bit instructions.

Bus speeds and widths have increased use to faster processors

and the needs of multimedia applications. Typical bus names and

widths are:

Industry Standard Architecture (ISA) 8 or 16 bits extended

industry Standard Architecture (EISA) 8 or 16 bits

Micro channel Architecture (MCA) 16 or 32 bits

VESA Local Bus (VLB) 32 bits

Peripheral component Interconnect (PCI) 32 or 64 bits

Accelerated Graphics Port (AGP) 32 bits


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SOUND CARDS

The voice in your computer that lets you know when youve

received a new email is made possible by the sound card. Before the

arrival of sound cards Personal Computers (PCs) were limited to

beeps from a tiny speaker on the motherboard. In the late 1980 s

sound cards ushered in the multimedia PC and took computer games

to a whole different level.

In 1989 Creative labs introduced the Creative labs

SoundBlaster@ Card Since then many other companies haveintroduced sound cards and Creative has continued to improve the

Sound Blaster line

Anatomy of a sound Card: A typical sound card has:

A digital signal processor (DSP) that handles most

computations

A digital to analog converter (DAC) for audio leaving the

computer

An analog to digital converter (ADC) for audio coming into the

computer

Read only memory (ROM) or Flash memory for storing date

Musical instrument digital interface (MIDI) for connecting to

external music equipment (for many cards, the game port is

also used to connect an external MIDI adapter)


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Jacks for connecting speakers and microphones, as well as line

in and line out

A game port for connecting a joystick or gamepad

Current sound cards usually plug into a peripheral Component

interconnect (PCI) slot, while some older or inexpensive cards may

use the industry standard architecture (ISA) bus. Many of the

computers available today incorporate the sound card as a chips right

on the motherboard. This leaves another slot open for other

peripherals the sound blaster Pro is considered the de facto standard

for sound cards. Virtually every sound card on the market today

includes sound blaster pro compatibility as a minimum.

Often different brands of sound cards from different manufactures

use the same chipset. The basic chipset comes from a third party

vendor. The sound card manufacturer then adds various other

functions and bundled software to help differentiate their product.

Sound cards may be connected to:

Headphones

Amplified speakers

An analog input source

Microphone

Radio

Tape deck

CD player


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A digital input source

Digital audiotape (DAT)

CD-ROM drive

An analog output device tape deck

A digital output device

DAT

CD recordable (CD-R)

Some of the current high end sound cards offer four speaker

output and digital interface through a jack. For audiophiles there is a

new generation of digital sound cards. A digital sound card is practical

for applications that need digital sound such as CD-R and DAT

Staying digital without any conversion to or from analog helps prevent

what is called generational loss. Digital sound cards have provisions

for digital sound input and output so you can transfer data from DAT,

DVD of CD directly to your hard disk in your PC.

Catching the Wave:

Typically, a sound card can do four things with sound:

Play prerecorded music (from CDs or sound files, such as wav

or MP3), games or DVDs

Record audio in various media from external sources

microphone or tape player)

Synthesize sounds


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Process existing sounds

The DAC and ADC provide the means for getting the audio in and

out of the sound card while the DSP oversees the process. The DSP

also takes care of any alterations to the sound, such as echo or

reverb. Because the DSP focuses on the audio processing the

computers main processor can take care of other tasks.

Early sound cards used FM synthesis to create sounds FM

synthesis takes tones at varying frequencies and combines them to

create an approximation of a particular sound such as the blare of a

trumpet. While FM synthesis has matured to the point where it can

sound very realistic it does not compare to wavetable synthesis.

Wavetable synthesis works by recording a tiny sample of the actual

instrument with incredible accuracy. Wavetable synthesis has

become the standard for most sound cards, but some of the

Inexpensive brands still use FM synthesis. A few cards provide

both types.

Very sophisticated sound cards have more support for MIDI

instruments. Using a music program, a MIDI equipped music

instrument can be attached to the sound card to allow you to see on

the computer screen the music score of what youre playing.

Producing sound:

Lets say you speak into your computer microphone. A sound card

creates a sound file in wave format from the date input through the

microphone. The process of converting that data into a file to be

recorded to the hard disk is:


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The sound card receives a continuous analog waveform input

signal from the microphone jack. The analog signals received

vary in both amplitude and frequency.

Software in the computer selects which input (s) will be used

depending on whether the microphone sound is being mixed

with a CD in the CD-ROM drive.

The mixed, analog waveform signal is processed in real time by

an analog to digital converter (ADC) circuit chip, creating a

binary (digital) output of 1s and 0s.

The digital output from the ADC flows into the DSP. Is

programmed by a set of instructions stored on another chip on

the sound card. One of the functions of the DSP is to compress

the now digital date in order to save space. The DSP also

allows the computers to perform other tasks while this is taking

place.

The output from the DSP is fed to the computers date bus by

way of connections on the sound card (or traces on the

motherboard to and from the sound chipst).

The digital data is processed by the computers processor and

routed to the hard disk controller it is then sent on to the hard

disk drive as a recorded way file.

To listen to a prerecorded wave file, the process is simply reversed:


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Digital data is read from the hard disk and passed on to the

central processor.

The central processor passed the date to the DSP on the sound

card.

The DSP uncompressed the digital date.

The uncompressed, digital date stream from the DSP is

processed in real-time by a digital to analog converter (DAC)

circuit chip, creating an analog signal that you hear in the

headphones or through the speakers, depending on which is

connected to the sound cards headphone jack.

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Parts of Computer-CPU