Computer Fundamentals module 3

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INTRODUCTION TO COMPUTERS

Definition

A computer is an electronic device that is used for information

processing. It accepts data and instructions, stores it in its memory,

process and gives the required results as output.

The word Computer is derived from the Latin word Compute that

means manipulate or calculate.

Input Processing Memory Output



CAPABILITIES

Input & Output

Processing

Huge Data Storage

CHARACTERISTICS

High Speed

Accuracy

Reliability

Versatility

Diligence

Storage Capacity



TYPES

Micro Computer.

Mini or Midrange Computer.Mainframe Computer.

Super Computer.

Micro Computer

Mini Computer

PC¶s are called as Home computers

or Desktop computers.

Mainframe Computer Example: VAX-8000, UNIVAS

1100/60, IBM-3033/3090 etc.



Input

Unit

Primary Memory

Arithmetic and Logical Unit

Secondary Memory

Control Unit

Output

Unit

Memory

CPU

BLOCK DIAGRAM

SYSTEM UNIT



BASIC UNITS

Input Unit.

System Unit

Output Unit.

Input Unit.

Input unit is an external device that is connected to the

CPU. It is used to feed data and instructions for solving

the problem

Examples: Key Board, Mouse ,Scanner etc.



System Unit.

Once the data and instructions are received from the input they are

stored and processed in the system unit.

The system unit further consists of two sub-units.

They are:

Central Processing Unit.

Memory Unit.

It is generally called CPU. Once the data and instructions are

received from the input device, they are to be processed in this

unit. So, it can be considered as the heart and brain of the

computer system. Further, the CPU consists at two importantfunctional units.

Control unit

Arithmetic and Logic unit

Central Processing Unit



Memory Unit

It is a storage device. The memory unit is a device where the data

and instructions fed by the used are stored.

Primary memory

Secondary memory

Cache Memory

Primary Memory

The place where the data and instructions are stored.

Temporary memory.

Semiconductor memory.

Read Only Memory - ROM Random Access Memory - RAM



Permanent memory. Stores large amount of information for a long time.

Backup memory or an auxiliary memory.

Examples : FDD, HDD & CDROM

Secondary Memory

Cache Memory

High-speed memory and placed between the CPU and the main

memory.

The data and instructions stored in it are accessed at a higher

speed.

User cannot access this memory. Its stores data and instructions that are currently to be executed.



MAIN MEMORY

All instructions and data to beexecuted are stored temporarily

Access time is 80 ns

More capacity

Less costlier

CACHE MEMORY

Only goes instructions and data

that are immediately executed

are stored here.

Access time is 15 - 25 ns

Less capacity

More costlier

It is used to display the results obtained after execution of a

program. Whenever the user wants output from the computer,

The most commonly used display unit in the monitor.

Examples : Monitor, Printer, Plotters, Speakers etc.

Output Unit.



LIMITATIONS

Non Intelligent.

Inactive.



HARDWARE

Keyboard

It is the most common input device.

To enter both Alphanumerical &

character

Mechanical Typewriter Compatible Keyboards contain 108

Keys

Input Devices

The term hardware refers to the physical devices that you can see and

touch in a computer system. Thus, the input, output, storage, control

and processing devices are hardware.



Mouse

It is a small hand held pointing

device connected. It has a rotating ball at the bottom

and has two click buttons on the top.

Light Pen

It is a pencil shaped device. It is

used to select screen co-ordinates

by detecting the light coming form

illuminated points on the CRT

(Cathode Ray Tube) screen.

Joy Stick

It is a small rod (lever or stick)mounted on a rolling ball. This rod is

used to control the screen cursor.

It is mainly used for playing

Computer or TV games.



Scanner

It is used to acquire (scan) both

character and graphics required for image processing or character

recognition.

It scans the image of a photograph

or written information and

communicates it to the CPU

Microphone

It is an input device, used to feed the

audio input to the computer.

The microphone is directlyconnected to the CPU.



Output Devices

Monitor

It is an electronic device

Which is used to monitor the work

process taking place in the computer.

The output which is monitored on the

monitor screen is known as the softcopy.

Speaker

Listen to the audio output sent by theprocessor.



Printers

A printer is an electromechanical device which signals from the

computer and acts accordingly.

Characteristics

Speed

Quality of output

Printer memory (Buffer)

Type

Fonts, etc.,



Plotters

A device used to produce graphical

output. They are employed for plotting graphs,

charts and other designs on paper.

Flat Bed Plotter Drum Plotter



Secondary Storage Devices

Floppy Disk

Floppy diskette

Floppy is soft and flexible and disk

means circular thing

A floppy disk plate is a special polymer

called Mylar Stores in Tracks & Sectors

Slno Size Specification Capacity

1. 5.25 Inch DSDD

DSHD

360 KB

1.22 MB

2. 3.5 Inch DSDD

DSHD

720 KB

1.44 MB



Hard Disk

A hard disk is a group of round flat metal

plates which are coated with magnetic material Data is recorded on both the surfaces of a disk

The speed is generally in the range of 2400 ±

4700 rpm Stores in Tracks & Sectors

Stores in Tracks & Sectors.

The disk in the hade disk is called as Platter

and made up of semiconductor material

Advantages

Random access ± Data is located and accessed

directly for reading and writing

Reusability ± Data stored on these disks can

be used repeatedly.

Durability - They are less prone to damage

Disadvantages

Costlier as compared to magnetic tape

Hard disks are of heavy weight as compared

to magnetic tapes



CD-ROM

CD-ROM stands for Compact Disk-Read Only Memory.

Circular plastic plate which is coated

with a highly reflective material.

The data is recorded on this disk by

focusing a laser beam on the surface of

the disk The storage capacity of CD-ROM is 700

to 900 MB.



SOFTWARE

Set of Programs is an software.

Set of instructions is an program

Classification of Software

Software

Application

Software

System

Software

Utility

Software



Application Software

It is a general purpose program or a collection of programs written bythe users to solve a particular problem, in his/her area of interest.

For example: Payroll, Inventory system, Student Information System,

Library Management System etc.



System Software

It is a collection of programs written for computer system management. These programs are developed by the manufacturer. They are supervisory programs and

help in executing the user¶s programs effectively. We can classify system software

into the following three types.

A) SYSTEM MANAGEMENT PROGRAMS: -

Programs that manage the hardware, software, network and data

resources of the computer systems during the execution of the variousinformation-processing job of users. Eg. All Operating systems like Windows

98, 2000, XP,Unix, Linux, Novel Netware etc.

B) SYSTEM DEVELOPMENT PROGRAMS: -

Programs that help users develop information system programs and

procedures and prepare user programs for computer processing. Eg. C, C++,VB, Oracle, JAVA etc.



Managing Data Resources

Data Concepts

Character: The most basic logical data element is the

character, which consists of a single alphabetic, numeric or

other symbol.

Field: It consists of grouping of related characters. Ex.

Name, number, object, place, event etc.

Record: It represents grouping of related data fields. Thus, a

record represents a collection of attributes that describe anentity.



File: A group of related records is a data file.

Database: It is an integrated collection of logically related

data elements.It consolidates the records previously stored

in separate files into a common pool of data elements that provides data for many applications.



Types of Databases

1. Operational databases: Stores detailed data needed tosupport the business processes and operations of a

company. Ex: Inventory database, customer database,

human resource database etc.

2. Distributed databases: It involves replicating anddistributing copies or parts of databases to network servers

at a variety of sites. These databases can reside on network

servers on the world wide web, corporate intranets,

extranets or on other company networks.

Done to improve database performance at end user worksites.



3. External databases: Access to a wealth of information

from external databases is available for a fee fromcommercial online services, with or without charge from

many sources on the world wide web.

Provides an endless variety of hyper linked pages of

multimedia documents for you to access.

4. Hypermedia databases: Stores information in a

hypermedia database consisting of hyperlinked pages of

multimedia (text, graphic, photographic images, video clips,

audio segments etc)



ZEROETH GENERATION

Man used his fingers, ropes, beads, bones,

pebbles and other objects for counting.

Abacus, Pascaline, Difference & Anyliticalengines

Electricity was not yet invented



FIRST GENERATION,

1947 ± 1956: The Vacuum Tube

y The first generation of computers, characterized byvacuum tubes, started in 1951 with the creation of -

UNIVAC (Universal Automatic Computer) ± a

tabulating machine which won the contest for thefastest machine which could count the US 1890 census.

VACUUM TUBES ± electronic tubes about the size of light bulbs.



First Generation (1950¶s):

y The vacuum tubes were used in the circuits of these

computers.

y The input and output operations were done using punched

card technology.

y For external storage, magnetic tapes were used.

y The machine was capable to do one job at a time, therefore

batch processing was adopted.

y The language used by these computers was machine

language and assembly language.

y Example of Computers: UNIVAC, IBM 650 etc.



DISADVANTAGES:

yThey generate more heat causing

many problems in temperature

regulation and climate control.

yTubes were subject to frequent burn-out.



SECOND GENERATION,

1957 ± 1963: The TransistorThe year 1959 marked the invention of transistors, whichcharacterized the second generation of computers.

This invention of the transistor which was faster, smaller andrequired considerably less power to operate

TRANSISTOR ± was a three-legged component which shrunk thesize of the first generation computers. Occupied only 1/100th of thespace occupied by a vacuum tube

More reliable, had greater computational speed, required no warm-up time and consumed far less electricity.



y Transistors were used in the circuits.

y The input operations were performed using punched cards and

magnetic tapes and for output operations, punched cards and papers were used.

y For external storage magnetic tapes were used.

y The orientation was towards multiple users i.e. the machinewas capable to process multiple tasks concurrently.

y The high level languages like FORTRAN, COBOL, BASICetc. were used as the languages by the computer.

y Example of Computers: IBM 1400 and 7000 series, GeneralElectric 635 etc.

Second Generation (1960¶s



THIRD GENERATION,

1964 ± 1979: The Integrated Circuit

Third generation computers arose in 1965 with the invention

of smaller electronic circuits called integrated circuits

(IC¶S)

INTEGRATED CIRCUITS ± are square silicon chipscontaining circuitry that can perform the functions of

hundreds of transistors.



Third Generation (1970¶s):

y Integrated circuits replaced transistors. Inspite of their

y smaller size they were capable to perform better than

transistors.

y For data input and output operations monitors and

keyboards replaced the punched cards.

y For external storage magnetic disks were used.

y

Sophisticated operating systems, which were capable of handling several jobs concurrently were used.

y More advanced high level languages like PASCAL were used.

y Example of computers: IBM System



ADVANTAGES:

yRELIABILITY ± Unlike vacuum tubes,

silicon will not break down easily. It is

very seldom that you will have to replaceit.

yLOW COST ± Silicon chips are

relatively cheap because of their smallsize and availability in the market. It also

consumes less electricity.



FOURTH GENERATION,

1980 ± present: The Microprocessor

y Marked by the use of microprocessor

y MICROPROCESSOR ± is a silicon chip that contains the

CPU ± part of the computer where all processing takes

place.4004 chip ± was the first microprocessor introduced by Intel

Corporation.



Fourth Generation (1980¶s):y The circuits used VLSI and microprocessors of virtually microscopic

size, which led to drastic cut on the size of computer.

y The input output devices were the same monitors, keyboard, printer

etc.Micro computers have evolved.Magnetic disks were the primary devices used for external storage.The use of special software for maintaining large data bases became

popular.

y The application software for micro computer essentially became popular in this generation.

y Example of computers: IBM Systems



Fifth Generation (late 1990¶s):

y The computers of this generation use optic fibre

technology to handle Artificial Intelligence.

y These computers have capacity to think and reason which

can be used to solve problems where human intelligence isrequired.

y Expert Systems are examples of systems implementing

y Artificial Intelligence (AI).



yIs classified as fourth generationcomputers.

yFaster, more powerful, tremendous data

storage and processing capacityy New brands and models would come out

the market almost every other month.

yMany clones or imitations of the IBMhave become even more powerful and alot cheaper.



yComputers became more affordable

y Computers an now be found in homes, schools, offices etc.

y There has been a tremendous improvement in softwaretechnology

y

Different software applications to choose from: word processing,spreadsheets, database management, games and entertainment.

y Computer subjects are now being offered not just to collegestudents but even to high school and elementary.

y Computers are now used as an aid in teaching math, science etc.



Operating Systemy A program that controls the execution of application

programs

y

An interface between applications and hardware



Operating System Objectivesy Convenience

y Makes the computer more convenient to use

yEfficiencyy Allows computer system resources to be used in an efficient

manner

y Ability to evolve

y Permit effective development, testing, and introduction of new system functions without interfering with service



Layers of Computer System



Services Provided by the

Operating Systemy Program development

y Editors and debuggers

yProgram execution

y Access to I/O devices

y Controlled access to files

y System access




Operating Systemy Error detection and response

y Internal and external hardware errors

y

Memory error y Device failure

y Software errors

y Arithmetic overflow

y Access forbidden memory locations

y Operating system cannot grant request of application




Operating Systemy Accounting

y Collect usage statistics

y

Monitor performancey Used to anticipate future enhancements

y Used for billing purposes



Operating Systemy Responsible for managing resources

y Functions same way as ordinary computer software

y

It is program that is executedy Operating system relinquishes control of the processor



y Portion of operating system that is in main memory

y Contains most frequently used functions

yAlso called the nucleus



Evolution of an Operating Systemy Hardware upgrades plus new types of hardware

y New services

yFixes



Evolution of Operating

Systemsy Serial Processing

y No operating system

y

Machines run from a console with display lights, toggleswitches, input device, and printer

y Schedule time

y Setup included loading the compiler, source program, saving

compiled program, and loading and linking



Evolution of Operating

Systemsy Simple Batch Systems

y Monitors

y Software that controls the sequence of events

y Batch jobs together

y Program branches back to monitor when finished



Job Control Language (JCL)y Special type of programming language

y Provides instruction to the monitor

y

What compiler to usey What data to use



Hardware Featuresy Memory protection

y Do not allow the memory area containing the monitor to be

altered

y Timer

y Prevents a job from monopolizing the system



Hardware Featuresy Privileged instructions

y Certain machine level instructions can only be executed by

the monitor

y Interrupts

y Early computer models did not have this capability



Memory Protectiony User program executes in user mode

y Certain instructions may not be executed

y

Monitor executes in system modey Kernel mode

y Privileged instructions are executed

y Protected areas of memory may be accessed



I/O Devices Slow



Uniprogrammingy Processor must wait for I/O instruction to

complete before preceding



Multiprogrammingy When one job needs to wait for I/O, the

processor can switch to the other job



Multiprogramming



Utilization Histograms



Example



Time Sharingy Using multiprogramming to handle multiple interactive

jobs

y

Processor¶s time is shared among multiple usersy Multiple users simultaneously access the system through

terminals



Compatible Time-Sharing System

(CTSS)

y First time-sharing system developed at MIT



Major Achievementsy Processes

y Memory Management

yInformation protection and security

y Scheduling and resource management

y System structure



Processes

y A program in execution

y An instance of a program running on a computer

y The entity that can be assigned to and executed on a processor

y A unit of activity characterized by a single sequentialthread of execution, a current state, and an associated setof system resources



Process

y Consists of three components

y An executable program

y

Associated data needed by the programy Execution context of the program

y All information the operating system needs to manage the process



Process



Memory Managementy Process isolation

y Automatic allocation and management

y

Support of modular programmingy Protection and access control

y Long-term storage



Virtual Memory Addressing

I f ti P t ti d



Information Protection and

Securityy Availability

y Concerned with protecting the system against interruption

y

Confidentialityy Assuring that users cannot read data for which access is

unauthorized



Information Protection and Security

y Data integrity

y Protection of data from unauthorized modification

y

Authenticityy Concerned with the proper verification of the identity of

users and the validity of messages or data

Scheduling and Resource



Scheduling and Resource

Managementy Fairness

y Give equal and fair access to resources

y Differential responsiveness

y

Discriminate among different classes of jobsy Efficiency

y Maximize throughput, minimize response time, and

accommodate as many uses as possible

Key Elements of



K ey Elements of

Operating System



System Structurey View the system as a series of levels

y Each level performs a related subset of functions

y

Each level relies on the next lower level to perform more primitive functions

y This decomposes a problem into a number of more

manageable subproblems

Multiprogramming and



Multiprogramming and

Multiprocessing



Modern Operating Systemsy Distributed operating systems

y Provides the illusion of a single main memory space and

single secondary memory space



Modern Operating Systems

y Object-oriented design

y Used for adding modular extensions to a small kernel

y Enables programmers to customize an operating system

without disrupting system integrity



Operating System Organizationy Modified microkernel architecture

y Not a pure microkernel

y Many system functions outside of the microkernel run in

kernel mode

y Any module can be removed, upgraded, or replaced

without rewriting the entire system



Windows Executivey I/O manager

y Cache manager

y Object manager

y Plug and play manager

y Power manager

y Security reference monitor

y Virtual memory manager

y Process/thread manager

y Configuration manager

y Local procedure call (LPC) facility



UNIX



UNIX K ernel



Modern UNIX K ernel



Modern UNIX Systemsy System V Release 4 (SVR4)

y Solaris 9

y

4.4BSDy Linux



Generation of Languagesy First Generation Languages

y Machine Language: consists of group of binary code, or

bytes that represents every thing from characters,

arithmetic & logic operations to store locations in RAM &

CPU

y Second Generation Languages

y

Assembler Languages:

to save programming time, thelong strings of 0¶s & 1¶s that represents each command,

were represent by , or assembled into, a single three or

four letters instructions.



y Third Generation Languages

y High Level Languages: user instructions which are called

statements translating HLL into Machine languages

program called ³Compiler´ or ³interpreters´

y Easy to learn & program than the assembler

y E.g., FORTRAN ± FOR mula TRANslator

y COBOL ± COmmon Business Oriented Language

y BASIC ± Beginners All purpose Symbolic Instruction Code



y Fourth Generation Languages : Application program

develop more easier connected to DBMS. Many routine

procedures are programmed & can be incorporated into a

program with single procedure.

y Command more in English.



Telecommunicationsy Tele (Far) + Communications

y Early telecommunications

y smoke signals and drums

y visual telegraphy (or semaphore in 1792)

y Telegraph and telephone

y Telegraph (1839)

y Telephone (1876)

y Radio and television

y Telephony

y Voice and Data

Communications and



Networksy Data Communications

y Transmission of signals

y Encoding, interfacing, signal integrity, multiplexing etc.

y Networking

y Topology & architecture used to interconnect devices

y Networks of communication systems



Network Trends (1980-Present)

Microcontroller Networking

Wireless

Voice, Image, Data, Video

Integrated Systems!

Microcontroller



Communication Systemsy Process describing transfer of information, data, instructions betweenone or more systems through some media

y Examplesy people, computers, cell phones, etc.

y Computer communication systems

y Signals passing through the communication channel can be Digital, or analog

y Analog signals: continuous electrical waves

y Digital signals: individual electrical pulses (bits)

y Receivers and transmitters: desktop computers, mainframe computers,

etc.

TX

RX

RX

RX

Communication channel

Communication

media

Amp/Adaptor



Communication Systems



Communications Componentsy Basic components of a

communication system

y Communication technologies

y Communication devices

y Communication channels

y Communication software



A Communications Model



Communications Tasks

Transmission system utilization Addressing

Interfacing Routing

Signal generation Recovery

Synchronization Message formatting

Exchange management Security

Error detection and correction Network management

Flow control



Data Communications Model



Communication Technology Applications

voice mail Twitt

er

e-

mail

instant

messagingchat rooms

newsgroup

s

telephony videoconferencing

collaboration groupware global positioning

system (GPS)



Communication Technologies -

Applicationsy Different technologies allowing us to communicate

y Examples: Voice mail, fax, email, instant message, chat rooms,news groups, telephony, GPS, and more

y Voice mail: Similar to answering machine but digitized

y Fax: Sending hardcopy of text or photographs between computers usingfax modem

y Email: electronic mail ± sending text, files, images between differentcomputer networks - must have email software

y More than 1.3 billion people send 244 billion messages monthly!

y Chat rooms: Allows communications in real time when connected tothe Internet

y

Telephony: Talking to other people over the Internet (also called VoIP)y Sends digitized audio signals over the Internet

y Requires Internet telephone software

y Groupware: Software application allowing a group of people tocommunicate with each other (exchange data)

y Address book, appointment book, schedules, etc.



Communication Devicesy Any type of hardware capable of transmitting data, instructions, and

information between devices

y Functioning as receiver, transmitter, adaptor, converter

y Basic characteristics: How fast, how far, how much data!

y Examples: Dial-up modems, ISDN[Integrated service Digital Network], DSLmodems, network interface cards

y Dial-up modem: uses standard phone linesy Converts digital information into analog

y Consists of a modulator and a demodulator

y Can be external, internal, wireless

y Cable modem: a modem that transmits and receives data over the cabletelevision (CATV) network

y Also called broadband modem (carrying multiple signals)y The incoming signal is split

y Requires a cable modem

y Network interface cards: Adaptor cards residing in the computer totransmit and receiver data over the network (NIC)

y Operate with different network technologies (e.g., Ethernet)



Communication Channelsy A channel is a path between two communication devices

y Channel capacity: How much data can be passed through

the channel (bit/sec)

y Also called channel bandwidth

y The smaller the pipe the slower data transfer!

y Consists of one or more transmission media

y Materials carrying the signal

y Two types:

y Physical: wire cable

y Wireless: Air destination

network

server

T1

lines

T1

lines

T1

lines

T3

lines



Physical Transmission Mediay A tangible media

y Examples: Twisted-pair cable, coaxial cable, Fiber-optics, etc.

y Twisted-pair cable:

y One or more twisted wires bundled together (why?)

y Made of copper y Coax-Cable:

y Consists of single copper wire surrounded by three layers of insulatingand metal materials

y Typically used for cable TV

y Fiber-optics:

y Strands of glass or plastic used to transmit lighty Very high capacity, low noise, small size, less suitable to natural

disturbances



Physical Transmission Media

plastic outer

coating

woven or

braided metal

insulating

material

copper wire

twisted-pair cable twisted-pair wire

protective

coating

glass cladding

optical fiber

core



Wireless Transmission Mediay Broadcast Radio

y Distribute signals through the air over long distance

y Uses an antenna

y

Typically for stationary locationsy Can be short range

y Cellular Radio

y A form of broadcast radio used for mobile communication

y

High frequency radio waves to transmitvoice or data

y Utilizes frequency-reuse



Wireless Transmission Mediay Microwaves

y Radio waves providing high speedtransmission

y They are point-to-point (can¶t be obstructed)

y Used for satellite communication

y Infrared (IR)y Wireless transmission media that sends signals

using infrared light- waves - Such as?



Physical Transmission Media

100 Mbps is how many bits per

sec?

Which is bigger:

10,000 Mbps, 0.01Tbps or

Wireless channel

capacity:



Networksy Collection of computers and devices connected together

y Used to transfer information or files, share resources, etc.

y What is the largest network?

y Characterized based on their geographical coverage, speed, capacities

y Networks are categorized based on the following characteristics:

y Network coverage: LAN, MAN, WAN

y Network topologies: how the computers are connected together

y Network technologies

y Network architecture



Network coveragey

Local Area Networks: y Used for small networks (school, home, office)

y Examples and configurations:

y Wireless LAN or Switched LAN

y Peer-2-PEER : connecting several computers together (<10)

y Client/Server : The serves shares its resources between

different clientsy Metropolitan Area Network

y Backbone network connecting all LANs

y Can cover a city or the entire country

y Wide Area Network

y

Typically between cities and countriesy Technology:

y Circuit Switch, Packet Switch, Frame Relay, ATM



LAN v.s WANLAN - Local Area Network a group of

computers connected within a building or a

campus (Example of LAN may consist of

computers located on a single floor or a

building or it might link all the computers in a

small company.

WAN - A network consisting of

computers of LAN's connected

across a distance WAN can cover

small to large distances, usingdifferent topologies such as telephone

lines, fiber optic cabling, satellite

transmissions and microwave

transmissions.



Network Topologiesy Configuration or physical arrangement in which devices are connected

together

y BUS networks: Single central cable connected a number of devices

y Easy and cheap

y

Popular for LANsy RING networks: a number of computers are connected on a closed loop

y Covers large distances

y Primarily used for LANs and WANs

y STAR networks: connecting all devices to a central unit

y All computers are connected to a central device called hub

y All data must pass through the huby What is the problem with this?

y Susceptible to failure



Network Topologiespersonal

computer

personal

computer

personal

computer

personal

computer

personal

computer

host

computer

printer

file server

personal computer

personal computer

personal computer

personal computer



Network Architecturey Refers to how the computer or devices are designed in a network

y Basic types:

y Centralized ± using mainframesy Peer-2-Peer :

y Each computer (peer) has equal responsibilities, capacities, sharing hardware, data,with the other computers on the peer-to-peer network

y

Good for small businesses and home networksy Simple and inexpensive

y Client/Server :

y All clients must request service from the server

y The server is also called a ho st

y Different servers perform different tasks: F ile server , network server , etc.

clien

t

clien

t

clien

t

serv

er

laser

printer



(Data) Network Technologiesy Vary depending on the type of devices we use for

interconnecting computers and devices together

y Ethernet:y LAN technology allowing computers to access the network

y Susceptible to collision

y Can be based on BUS or STAR topologies

y Physical layer y Gigabit Ethernet using optical fiber, twisted pair cable, or

balanced copper cable

Project

Topic



Network Examplesy Interplanetary (Internet) Network

http://www.ece.gatech.edu/research/labs/ bwn/deepspace/

Project

Topic



Network Example:

Optical Networksy Fiber-to-the-x

y Broadband network architecture thatuses optical fiber to replace copper

y Used for last mile telecommunications

y Fiber Distribution Network (reaching

different customers)

Project

Topic

Network Example:



Network Example:Telephone Networks



Network ExamplesPublic Telephone

Network

T-Carrier Dedicated

Lines

Dail-up

DSL ISDN

ATM

What about Cable Internet Services?



Cellular Network Examplesy 0G

y Single, powerful base station covering a wide area, and eachtelephone would effectively monopolize a channel over thatwhole area while in use (developed in 40¶s)

y No frequency use or handoff (basis of modern cell phonetechnology)

y 1Gy Fully automatic cellular networks

y introduced in the early to mid 1980s

y2Gy Introduced in 1991 in Finland on the GSM standard

y Offered the first data service with person-to-person SMS textmessaging

C ll l N k E l



Cellular Network Examplesy 3G:

y Faster than PCS; Used for multimedia andgraphics

y Compared to 2G and 2.5G services, 3G allowssimultaneous use of speech and data services andhigher data rates (up to 14.4 Mbit/s on the

downlink and 5.8 Mbit/s.y 4G:

y Fourth generation of cellular wireless;

y providing a comprehensive and secure IP basedservice to users "Anytime, Anywhere" at highdata rates



Wireless Technologies [WAP]y The Wireless Application protocol [WAP] is a set of

specifications, developed by WAP forum that lets

developers using wireless mark up language[WMP] built

network applications designed for handled wirelessdevices.

y Wire-free World: (Blue Tooth)

Is a computing, networking and telecommunications

industry specification that enables mobile phones,

Computers and other WIDs to talk each other using radio

waves.

Wireless internet as the way



Wireless internet as the way

of the Futurey 1. Blue tooth is a global defacto standard for wireless connectivity.

Based on low cost short range radio link. Blue tooth cuts that cards

that used to tie up digital devices.

y 2. UMTS (Universal Mobile Telecommunication System) is also calle

third generation broadband, pocket based transmission of text,

digitised voice, video and multimedia.

y 3. GPRS (General Pocket Radio Services) is packet based wireless

communication service that promises data transmission and continuou

connection to the internet for mobile phone and computer user.y 4. i mode is wireless technology developed by Japanese Company

NTT DoCoMo that enables users to access internet services via their

cellular phones.

Internet, Intranet and



Internet, Intranet and

ExtranetIntranet Extranet



Internet



Electronic Market1. Broker Model :

y Attractive packaging

y Efficient delivery

y Accurate payment handling

2. Customization model :

selling of customized products to mass market

3. Contact Model :

Matching prospective supplier of goods and services with

buyers.

Computer Fundamentals module 3

Documents

Transcript of Computer Fundamentals module 3