how computer works final

7/29/2019 How Computer Works Final

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INTRODUCTION:

Our lifestyles have undergone a sea change with the advancement in technology especially

in the field of computers. Computers are an integral part of our lifestyles today and are

found at offices, homes, schools, colleges, hotels, shops etc. This advance in technology has

made our lives easy and comfortable. For instance, we can execute a number of activities

using computer based systems- we can write a draft on word processor and email it, make

calculations using an electronic spreadsheet and incorporate graphics, create a database of

friends with their phone numbers, addresses and e-mail ids etc. It is an arduous process to

perform these activities using existing traditional methods. Computers can also simplifyother tasks such as word processing, designing, web site development, database

management etc. Therefore, a computer should be referred to as a data processor.

The computer comprises of technologically advanced hardware put together to work at

great speed. To accomplish its various tasks, the computer is made of different parts, each

serving a particular purpose in conjunction with other parts. In other words, a 'computer' is

an ensemble of different machines that you will be using to accomplish your job. A

computer is primarily made of the Central Processing Unit (usually referred to as the

computer), the monitor, the keyboard and the mouse. Other pieces of hardware, commonly

referred to as peripherals, can enhance or improve your experience with the computer.

ADVANTAGES:

Compared to traditional systems, computers offer many noteworthy advantages. This is one

reason that traditional systems are being replaced rapidly by computer-based systems. The

main advantages offered by computers are as follows:

High Accuracy

Superior Speed of Operation

Large Storage Capacity

User-friendly Features

Portability


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Platform independence

Economical in the long term

COMPONENTS:

HARDWARE SOFTWARE

Basic Elements of Computer System

1. Mouse

2. Keyboard

3. Monitor

4. Memory

5. CPU

6. Motherboard

7. Hard Disk8. Speakers

9. Modem

10.Power Supply

11.Processor


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1. Mouse

In computing, a mouse is a pointing device that functions by detecting two-

dimensional motion relative to its supporting surface. Physically, a mouse consists of an

object held under one of the user's hands, with one or more buttons.

The mouse sometimes features other elements, such as "wheels", which allow the user to

perform various system-dependent operations, or extra buttons or features that can add

more control or dimensional input. The mouse's motion typically translates into the motion

of a pointer on a display, which allows for fine control of a graphical user interface.

Types Of Mouse :-

a) Optical Mouse

b) Mechanical Mouse

c) Wireless Mouse

2. Keyboard


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In computing, a keyboard is a typewriter-style device, which uses an arrangement of

buttons or keys, to act as mechanical levers or electronic switches. Following the decline

of punch cards and paper tape, interaction via teleprinter-style keyboards became the

main input device for computers.

A keyboard typically has characters engraved or printed on the keys and each press of a key

typically corresponds to a single written symbol. However, to produce some symbols

requires pressing and holding several keys simultaneously or in sequence. While most

keyboard keys produce letters,numbers or signs (characters), other keys or simultaneous

key presses can produce actions or computer commands.

Despite the development of alternative input devices, such as the mouse, touchscreen, pen

devices, character recognition and voice recognition, the keyboard remains the most

commonly used and most versatile device used for direct (human) input into computers.

In normal usage, the keyboard is used to type text and numbers into a word processor, text

editor or other programs. In a modern computer, the interpretation of key presses is

generally left to the software. A computer keyboard distinguishes each physical key from

every other and reports all key presses to the controlling software. Keyboards are also used

for computer gaming, either with regular keyboards or by using keyboards with special

gaming features, which can expedite frequently used keystroke combinations. A keyboard is

also used to give commands to the operating system of a computer, such

as Windows' Control-Alt-Delete combination, which brings up a task window or shuts down

the machine. Keyboards are the only way to enter commands on a command-line interface.

3. Monitor

A monitor or display (also called screen or visual display unit) is an electronic visual

display for computers. The monitor comprises the display device, circuitry and an enclosure.

The display device in modern monitors is typically a thin film transistor liquid crystal


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display (TFT-LCD) thin panel, while older monitors use a cathode ray tube (CRT) about as

deep as the screen size.

Originally, computer monitors were used for data processing while television receivers were

used for entertainment. From the 1980s onwards, computers (and their monitors) have

been used for both data processing and entertainment, while televisions have implemented

some computer functionality. The common aspect ratio of televisions, and then computer

monitors, has also changed from 4:3 to 16:9 (and 16:10).

4. Motherboard

A motherboard (sometimes alternatively known as the mainboard, system board, planar

board or logic board) is a printed circuit board (PCB) found in all modern computers which

holds many of the crucial components of the system, such as the central processing

unit (CPU) and memory, and provides connectors for other peripherals.

Motherboardspecifically refers to a PCB with expansion capability. The term mainboardis

applied to devices with a single board and no additional expansions or capability. In modern

terms this would include controlling boards in televisions, washing machines and

other embedded systems.


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5. Hard disk drive

A hard disk drive (HDD; also hard drive, hard disk, or disk drive) is a magnetic data storage

device featuring low cost, non-volatility andrandom-access. Introduced by IBM in 1956,

HDDs have been the dominant secondary storage device in general purpose

computers since the early 1960s.[3]

They have maintained this position against competing

products, including today's solid-state drives, through technological advances in recording

capacity and continued improvements in cost per unit of storage and reliability.

An HDD consists of one or more rigid ("hard") rapidly rotating discs (platters) coated withmagnetic material. Magnetic heads arranged on a moving actuator arm read and write data

to the surfaces. The read-write heads are supported on a thin layer of air inside the enclosed

disk unit with only tiny gaps between the heads and the disk surface.

HDD capacity is specified in multiples of 1000 - a 1-terabyte (TB) drive has a capacity of

1,024 gigabytes (GB 1 billion bytes). However, due to system usage and reporting not all of

the specified storage is ever available for user storage.

The primary performance measurements of an HDD are the time to move the heads to a file

(average access time) plus the time it takes for the file to move under its head (averagelatency, a function of the physical rotational speed in revolutions per minute) and the speed

at which the file is transmitted (data rate). The original hard drive was the size of two

refrigerators, but modern HDDs typically are in a 3.5-inch form factor in desktop computers

and servers and 2.5-inch form factor in laptops. HDDs are connected to systems by

standard interface cables such as SATA (Serial ATA),USB or SAS (Serial Attached SCSI) cables.

More than 200 companies have manufactured HDD units but today only four remain,

Western Digital, Seagate, Simmtronics, and Toshiba. Worldwide revenues for HDDs

shipments are expected to reach $38 billion in 2012, up about 19% from $32 billion in 2011.


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6. Modem

A modem (modulator-demodulator) is a device that modulates an analog carrier signal to

encode digital information, and also demodulates such a carrier signal to decode the

transmitted information. The goal is to produce a signal that can be transmitted easily and

decoded to reproduce the original digital data. Modems can be used over any means of

transmitting analog signals, from light emitting diodes to radio. The most familiar example is

avoice band modem that turns the digital data of a personal computer into

modulated electrical signals in the voice frequency range of a telephonechannel. These

signals can be transmitted over telephone lines and demodulated by another modem at the

receiver side to recover the digital data.

Modems are generally classified by the amount of data they can send in a given unit of time,usually expressed in bits per second (bit/s, or bps), orbytes per second (B/s). Modems can

alternatively be classified by their symbol rate, measured in baud. The baudunit denotes

symbols per second, or the number of times per second the modem sends a new signal. For

example, the ITU V.21 standard used audio frequency shift keying, that is to say, tones of

different frequencies, with two possible frequencies corresponding to two distinct symbols

(or one bit per symbol), to carry 300 bits per second using 300 baud. By contrast, the

original ITU V.22 standard, which was able to transmit and receive four distinct symbols

(two bits per symbol), handled 1,200 bit/s by sending 600 symbols per second (600 baud)

using phase shift keying.


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7. Speakers

Computer speakers, or multimedia speakers, are speakers external to a computer, that

disable the lower fidelity built-in speaker. They often have a low-power internal amplifier.

The standard audio connection is a 3.5 mm (approximately 1/8 inch) stereo jack plug often

color-coded lime green (following the PC 99 standard) for computer sound cards. A plug and

socket for a two-wire (signal and ground) coaxial cable is widely used to

connect analogaudio and video components. Rows of RCA sockets are found on the backs of

stereo amplifier and numerous A/V products. The prong is 1/8" thick by 5/16" long. A few

use an RCA connector for input. There are also USB speakers which are powered from the

5 volts at 500 milliamps provided by the USB port, allowing about 2.5 watts of output

power.

Computer speakers range widely in quality and in price. The computer speakers typically

packaged with computer systems are small, plastic, and have mediocre sound quality. Some

computer speakers have equalization features such as bass and treble controls.

The internal amplifiers require an external power source, usually an AC adapter. More

sophisticated computer speakers can have a subwoofer unit, to enhance bass output, and

these units usually include the power amplifiers both for the bass speaker, and the small

satellite speakers.

Some computer displays have rather basic speakers built-in. Laptops come with integrated

speakers. Restricted space available in laptops means these speakers usually produce low-

quality sound.

For some users, a lead connecting computer sound output to an existing stereo system is

practical. This normally yields much better results than small low-cost computer speakers.

Computer speakers can also serve as an economy amplifier for MP3 player use for those


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who wish to not use headphones, although some models of computer speakers have

headphone jacks of their own.

8. C.P.U.

A central processing unit (CPU), also referred to as a central processor unit, is the hardware

within a computer system which carries out theinstructions of a computer program by

performing the basic arithmetical, logical, and input/output operations of the system. The

term has been in use in the computer industry at least since the early 1960s.The form,

design, and implementation of CPUs have changed over the course of their history, but their

fundamental operation remains much the same.

On large machines, CPUs require one or more printed circuit boards. On personal

computers and small workstations, the CPU is housed in a single silicon chip called

a microprocessor. Since the 1970s the microprocessor class of CPUs has almost completely

overtaken all other CPU implementations. Modern CPUs are large scale integrated circuits in

packages typically less than four centimeters square, with hundreds of connecting pins.

Two typical components of a CPU are the arithmetic logic unit (ALU), which performs

arithmetic and logical operations, and the control unit (CU), which extracts instructions

from memory and decodes and executes them, calling on the ALU when necessary.Not all computational systems rely on a central processing unit. An array processor or vector

processor has multiple parallel computing elements, with no one unit considered the

"center". In the distributed computing model, problems are solved by a distributed

interconnected set of processors.


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9. Power Supply Unit of Computer

A power supply unit (PSU) converts mains AC to low-voltage regulated DC power for the

internal components of a computer. Modern personal computers universally use

a switched-mode power supply. Some power supplies have a manual selector for input

voltage, while others automatically adapt to the supply voltage.

Most modern desktop personal computer power supplies conform to the ATX specification,

which includes form factor and voltage tolerances. While an ATX power supply is connected

to the mains supply, it always provides a 5 V standby (5VSB) voltage so that the standby

functions on the computer and certain peripherals are powered. ATX power supplies are

turned on and off by a signal from the motherboard. They also provide a signal to the

motherboard to indicate when the DC voltages are in spec, so that the computer is able to

safely power up and boot. The most recent ATX PSU standard is version 2.31 of mid-2008.


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10.R.A.M

Random-access memory (RAM) is a form of computer data storage. A random-access

device allows stored data to be accessed in very nearly the same amount of time for any

storage location, so data can be accessed quickly in any random order. In contrast, other

data storage media such ashard disks, CDs, DVDs and magnetic tape, as well as early primary

memory types such as drum memory, read and write data only in a predetermined order,

consecutively, because of mechanical design limitations. Therefore the time to access a

given data location varies significantly depending on its physical location.

Today, random-access memory takes the form of integrated circuits. Strictly speaking,

modern types of DRAM are not random access, as data is read in bursts, although the

name DRAM / RAM has stuck. However, many types of SRAM, ROM, OTP, and NOR flash are

still random access even in a strict sense. RAM is often associated with volatile types of

memory (such as DRAM memory modules), where its stored information is lost if the poweris removed. Many other types of non-volatile memory are RAM as well, including most types

of ROM and a type of flash memory called NOR-Flash. The first RAM modules to come into

the market were created in 1951 and were sold until the late 1960s and early 1970s.


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11.Printer

A printer is a piece of hardware for a computer. It is a device that must be connected to a

computer which allows a user to print items on paper, such as letters and pictures. It can

also work with digital cameras to print directly without the use of a computer.

Types of Printers :-

Inkjet printers, also sometimes called bubble jet printers use colored ink they

put on a paper.

Plotters are large format inkjet printers, or printers that use special pens.

Laser printers transfer tiny particles of toner onto the paper.

Dot-matrix printers are now almost extinct. They used a ribbon and made a

lot of noise. There were models with 9 pins and models with 24 pins.

Dye sublimation printers produce very high quality images. Three colors are

used. Cyan, Magenta and Yellow. Each color is printed one at a time

from cellophane sheets. The image is the sealed with an clear top layer. Some

small photographic printers made by Kodak and Canon use this process.

Daisy Wheel printers are a typewriter printer; Results look hand-typed with

excellent looking text, no real graphics and very loud.


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12.Storage CD (compact disc): The most common type of removable media, suitable for music

and data

CD-ROM Drive: A device used for reading data from a CD

CD Writer: A device used for both reading and writing data to and from a CD

DVD (digital versatile disc): A popular type of removable media that is the same size

as a CD but stores up to 12 times as much information- the most common way of

transferring digital video and is popular for data storage

DVD-ROM Drive: A device used for reading data from a DVD

DVD Writer: A device used for both reading and writing data to and from a DVD

DVD-RAM Drive: A device used for rapid writing and reading of data from a special type

of DVD

Blu-ray Disc: A high density optical disc format for data and high-definition video that

can store 70 times as much information as a CD

BD-ROM Drive: A device used for reading data from a Blu-ray disc

BD Writer: A device used for both reading and writing data to and from a Blu-ray disc

HD DVD: A discontinued competitor to the Blu-ray format

Floppy disk: An outdated storage device consisting of a thin disk of a flexible

magnetic storage medium used today mainly for loading RAID drivers

Iomega Zip drive: An outdated medium-capacity removable disk storage system, first

introduced by Iomega in 1994

USB flash drive: A flash memory data storage device integrated with a USB interface,

typically small, lightweight, removable and rewritable with varying capacities from

hundreds of megabytes (in the same ballpark as CDs) to tens of gigabytes

(surpassing, at great expense, Blu-ray discs)

Tape drive: A device that reads and writes data on a magnetic tape, used for long

term storage and backups

SECONDARY STORAGE

This hardware keeps data inside the computer for later use and retains it even when the

computer has no power.

Hard disk: A device for medium-term storage of data

Solid-state drive: A device quite similar to the hard disk, but containing no moving

parts and which stores data in a digital format


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RAID array controller: A device to manage several internal or external hard disks and

optionally some peripherals in order to achieve performance or reliability

improvement in what is called a RAID array

Software

Computer software, or just software, is a collection of computer programs and

related data that provides the instructions for telling a computer what to do and how to

do it. Software refers to one or more computer programs and data held in the storage of

the computer for some reasons. In other words, software is a set ofprograms,

procedures, algorithms and its documentation concerned with the operation of a data

processing system. Program software performs the function of the program it

implements, either by directly providing instructions to the computer hardware or by

serving as input to another piece of software. The term was coined to contrast to the old

term hardware (meaning physical devices). In contrast to hardware, software "cannot be

touched".[1]

Software is also sometimes used in a more narrow sense,

meaning application software only. Sometimes the term includes data that has not

traditionally been associated with computers, such as film, tapes, and records.[2]

Computer software is so called to distinguish it from computer hardware, which

encompasses the physical interconnections and devices required to store and execute

(or run) the software. At the lowest level, executable code consists of machine language

instructions specific to an individual processor. A machine language consists of groups

of binary values signifying processor instructions that change the state of the computer


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from its preceding state. Programs are an ordered sequence of instructions for changing

the state of the computer in a particular sequence. It is usually written in high-level

programming languages that are easier and more efficient for humans to use (closer

to natural language) than machine language. High-level languages are compiled or

interpreted into machine language object code. Software may also be written inan assembly language, essentially, a mnemonic representation of a machine language

using a natural language alphabet. Assembly language must be assembled into object

code via an assembler.

Operating System

An operating system (OS) is a collection of software that manages computer

hardware resources and provides common services for computer programs. The operating

system is a vital component of the system software in a computer system. Application

programs require an operating system to function.

Time-sharing operating systems schedule tasks for efficient use of the system and may also

include accounting for cost allocation of processor time, mass storage, printing, and otherresources.

For hardware functions such as input and output and memory allocation, the operating

system acts as an intermediary between programs and the computer hardware, although

the application code is usually executed directly by the hardware and will frequently make

a system call to an OS function or be interrupted by it. Operating systems can be found on

almost any device that contains a computerfrom cellular phones and video game

consoles to supercomputers and web servers.


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Examples of popular modern operating systems include Android, BSD, iOS, Linux, Mac OS

X, Microsoft Windows, Windows Phone, and IBM z/OS. All these, except Windows and z/OS,

share roots in UNIX.

Types of Operating Systems :-

Real-time : A real-time operating system is a multitasking operating system that aims

at executing real-time applications. Real-time operating systems often use

specialized scheduling algorithms so that they can achieve a deterministic nature of

behavior. The main objective of real-time operating systems is their quick and

predictable response to events. They have an event-driven or time-sharing design

and often aspects of both. An event-driven system switches between tasks based on

their priorities or external events while time-sharing operating systems switch tasks

based on clock interrupts.

Multi-user : A multi-user operating system allows multiple users to access a

computer system concurrently. Time-sharing systems and Internet servers can be

classified as multi-user systems as they enable multiple-user access to a computer

through the sharing of time. Single-user operating systems, as opposed to multi-user

operating systems, are usable by a single user at a time. Being able to use multiple

accounts on a Windows operating system does not make it a multi-user system.

Rather, only the network administrator is the real user. But for a UNIX-like operating

system, it is possible for two users to log in at a time and this capability of the OS

makes it a multi-user operating system.

Multi-tasking vs. single-tasking : A multi-tasking operating system allows more than

one program to be running at a time, from the point of view of human time scales. A

single-tasking system has only one running program. Multi-tasking can be of two

types: pre-emptive or co-operative. In pre-emptive multitasking, the operating

system slices the CPU time and dedicates one slot to each of the programs. Unix-like

operating systems such as Solaris and Linux support pre-emptive multitasking, as

does AmigaOS. Cooperative multitasking is achieved by relying on each process to

give time to the other processes in a defined manner. 16-bit versions of Microsoft

Windows used cooperative multi-tasking. 32-bit versions, both Windows NT and

Win9x, used pre-emptive multi-tasking. Mac OS prior to OS X used to support

cooperative multitasking.

Distributed : A distributed operating system manages a group of independent

computers and makes them appear to be a single computer. The development of

networked computers that could be linked and communicate with each other gaverise to distributed computing. Distributed computations are carried out on more

than one machine. When computers in a group work in cooperation, they make a

distributed system.

Embedded : Embedded operating systems are designed to be used in embedded

computer systems. They are designed to operate on small machines like PDAs with

less autonomy. They are able to operate with a limited number of resources. They

are very compact and extremely efficient by design. Windows CE and Minix 3 are

some examples of embedded operating systems

How Computer Works


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To accomplish a task using a computer, you need a combination of hardware, software, and

input.

Modern computers are electronic and digital. The actual machinery -- wires,transistors, and

circuits -- is called hardware; the instructions and data are called software.All general-purpose computers require the following hardware components:

memory: enables a computer to store, at least temporarily, data and programs.

mass storagedevice: allows a computer to permanently retain large amounts of

data. Common mass storage devices include disk drives and tape drives.

input device: usually a keyboard and mouse, the input device is the conduit through

which data and instructions enter a computer.

output device: a display screen, printer, or other device that lets you see what the

computer has accomplished.

central processing unit(CPU): the heart of the computer, this is the component that

actually executes instructions.

It is not just one factor that is responsible for running a computer it is the combination of

above all the units thats responsible for running of the computer.

To understand the basic rudiments of the functioning of the computer refer to the basic

block diagram of a computer as shown in Fig. This flow of information holds true for all

types of computers such as Personal Computers, Laptops, Palmtops etc. In other words, the

fundamental principle of working is the same.

As shown in there are four main building blocks in a computer's functioning input,processor, output and memory. The data is entered through input devices like the keyboard,

disks or mouse. These input devices help convert data and programs into the language that

the computer can process.

The data received from the keyboard is processed by the CPU, i.e. the Central Processing

Unit. The CPU controls and manipulates the data that produce information. The CPU is

usually housed within the protective cartridge. The processed data is either stored in the

memory or sent to the output device, as per the command given by the user. The memory

unit holds data and program instructions for processing data. Output devices translate the

processed information from the computer into a form that we can understand.

how computer works final

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