COMPUTERS -INTRODUCTION

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What Is A Computer?

A computer is an electronic device, operating under the control of instructions (software) stored in its own memory unit, that can accept data (input), manipulate data (process), and produce information (output) from the processing. Generally, the term is used to describe a collection of devices that function together as a system.

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Devices that comprise a computer system

Printer (output)

Monitor (output)

Speaker (output)

Scanner (input)

Mouse (input)

Keyboard (input)

System unit(processor, memory…)

Storage devices

(CD-RW, Floppy, Hard disk, zip,…)

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What Does A Computer Do?

Computers can perform four general operations, which comprise the information processing cycle.

• Input

• Process

• Output

• Storage

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Data and Information

• All computer processing requires data, which is a collection of raw facts, figures and symbols, such as numbers, words, images, video and sound, given to the computer during the input phase.

• Computers manipulate data to create information. Information is data that is organized, meaningful, and useful.

• During the output Phase, the information that has been created is put into some form, such as a printed report.

• The information can also be put in computer storage for future use.

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Why Is A Computer So Powerful?

• The ability to perform the information processing cycle with amazing speed.

• Reliability (low failure rate).• Accuracy.• Ability to store huge amounts of data and

information.• Ability to communicate with other computers.

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How Does a Computer Know what to do?

• It must be given a detailed list of instructions, called a compute program or software, that tells it exactly what to do.

• Before processing a specific job, the computer program corresponding to that job must be stored in memory.

• Once the program is stored in memory the compute can start the operation by executing the program instructions one after the other.

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What Are The Primary Components Of A Computer ?

• Input devices.

• Central Processing Unit (containing the control unit and the arithmetic/logic unit).

• Memory.

• Output devices.

• Storage devices.

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Input Devices

• Keyboard.

• Mouse.

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The Keyboard

The most commonly used input device is the keyboard on which data is entered by manually keying in or typing certain keys. A keyboard typically has 101 or 105 keys.

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The Mouse

Is a pointing device which is used to control the movement of a mouse pointer on the screen to make selections from the screen. A mouse has one to five buttons. The bottom of the mouse is flat and contains a mechanism that detects movement of the mouse.

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The Central processing Unit

The central processing unit (CPU) contains electronic circuits that cause processing to occur. The CPU interprets instructions to the computer, performs the logical and arithmetic processing operations, and causes the input and output operations to occur. It is considered the “brain” of the computer.

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Memory

Memory also called Random Access Memory or RAM (temporary memory) is the main memory of the computer. It consists of electronic components that store data including numbers, letters of the alphabet, graphics and sound. Any information stored in RAM is lost when the computer is turned off.

Read Only Memory or ROM is memory that is etched on a chip that has start-up directions for your computer. It is permanent memory.

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Amount Of RAM In Computers

The amount of memory in computers is typically measured in kilobytes or megabytes. One kilobyte (K or KB) equals approximately 1,000 memory locations and one megabyte (M or MB) equals approximately one million locations A memory location, or byte, usually stores one character.

Therefore, a computer with 8 MB of memory can store approximately 8 million characters. One megabyte can hold approximately 500 pages of text information.

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Output Devices

Output devices make the information resulting from the processing available for use. The two output devices more commonly used are the printer and the computer screen.

The printer produces a hard copy of your output, and the computer screen produces a soft copy of your output.

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Storage Devices

Auxiliary storage devices are used to store data when they are not being used in memory. The most common types of auxiliary storage used on personal computers are floppy disks, hard disks and CD-ROM drives.

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Floppy DisksA floppy disk is a portable, inexpensive storage medium that consists of a thin, circular, flexible plastic disk with a magnetic coating enclosed in a square-shaped plastic shell.

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Structure Of Floppy Disks

• Initially Floppy disks were 8-inches wide, they then shrank to 5.25 inches, and today the most widely used floppy disks are 3.5 inches wide and can typically store 1.44 mega bytes of data.

• A floppy disk is a magnetic disk, which means that it used magnetic patterns to store data.

• Data in floppy disks can be read from and written to. • Formatting is the process of preparing a disk for reading

and writing.• A track is a narrow recording band that forms a full circle

on the surface of the disk.

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• The disk’s storage locations are divided into pie-shaped sections called sectors.

• A sectors is capable of holding 512 bytes of data.

• A typical floppy stores data on both sides and has 80 tracks on each side with 18 sectors per track.

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Hard Disks

• Another form of auxiliary storage is a hard disk. A hard disk consists of one or more rigid metal plates coated with a metal oxide material that allows data to be magnetically recorded on the surface of the platters.

• The hard disk platters spin at a high rate of speed, typically 5400 to 7200 revolutions per minute (RPM).

• Storage capacites of hard disks for personal computers range from 10 GB to 120 GB (one billion bytes are called a gigabyte).

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Compact Discs

• A compact disk (CD), also called an optical disc, is a flat round, portable storage medium that is usually 4.75 inch in diameter.

• A CD-ROM (read only memory), is a compact disc that used the same laser technology as audio CDs for recording music. In addition it can contain other types of data such as text, graphics, and video.

• The capacity of a CD-ROM is 650 MB of data.

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Computer Software

Computer software is the key to productive use of computers. Software can be categorized into two types:

• Operating system software

• Application software.

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Operating System Software

Operating system software tells the computer how to perform the functions of loading, storing and executing an application and how to transfer data.

Today, many computers use an operating system that has a graphical user interface (GUI) that provides visual clues such as icon symbols to help the user. Microsoft Windows 98 is a widely used graphical operating system. DOS (Disk Operating System) is an older but still widely used operating system that is text-based.

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Application Software

Application Software consists of programs that tell a computer how to produce information. Some of the more commonly used packages are:

• Word processing

• Electronic spreadsheet

• Database

• Presentation graphics

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Word Processing

• Word Processing software is used to create and print documents. A key advantage of word processing software is that users easily can make changes in documents.

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Electronic Spreadsheets

• Electronic spreadsheet software allows the user to add, subtract, and perform user-defined calculations on rows and columns of numbers. These numbers can be changed and the spreadsheet quickly recalculates the new results.

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Database Software

• Allows the user to enter, retrieve, and update data in an organized and efficient manner, with flexible inquiry and reporting capabilities.

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Presentation Graphics

• Presentation graphic software allows the user to create documents called slides to be used in making the presentations. Using special projection devices, the slides display as they appear on the computer screen.

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computer

• It is an automatic electronic apparatus for making calculations or controlling operations that are expressible in numerical or logical terms.

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ComputerAn electronic device

Can store and process data

Speed and accuracy

Access desired data

Not a master but a slave

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Personal ComputerMonitor

CPU Keyboard

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ELEMENTS OF A COMPUTER SYSTEM

Storage devices

Input devices

Output devicesComputer components

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Structure of Computer

central processing unit

Memory

ControlUnit

Arithmatic& LogicUnit

Inputdevice

OutputDevice

Storage

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MICROPROCESSORAND THE CPU

Arithmetic/Logic UnitArithmetic Operations - addition, subtraction, multiplication and division

Logical operations - comparing data using <, <=, =, >=, >

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COMPONENTS OF THE SYSTEM UNIT

Motherboard

Microprocessor and CPU

Upgrade Sockets

Memory

Coprocessors

Buses

Expansion Slots

Ports and Connectors

Bays

Power Supply

Sound Components

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MOTHERBOARDMain Board (System Board)

a Circuit Board Containing Electronic Components of System Unit

• Motherboard: The main circuit board responsible for checking that all the other circuit boards are eating properly and wearing clean clothes.

A Megabyte of Computer Jokess k satapathy

MICROPROCESSORAND THE CPU

Microprocessor - contains the central processing unit (CPU)

Top View Bottom View

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MICROPROCESSORAND THE CPU

System ClockControls timing of all computer operations

Generates electronic pulses at a fixed rate to synchronize different parts of the computer

One megahertz = 1 million pulses per second

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MEMORY

• Every computer has the same available memory: too little.

» Ken Skier, 1981

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MEMORY

Integrated circuits that temporarily store instructions (Programs) and data

Memory chips in the motherboard and some other circuit boards, e.g., video cards (see the slide on Expansion Slots)

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RANDOM ACCESS MEMORY

Main Memory

– volatile — gets erased when the computer is turned off

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MEMORY

RAMRAM chips are normally characterized by

The technology used (static, dynamic or others)

The memory size (4MB, 8MB … )

The access time (50 ns, 10ns, … )

Today, most RAM memory is installed using SIMM (Single in-line memory module)

DIMM (Dual in-line memory module)

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BUSES

Wires, OR

Etched lines on the circuit board, OR

Within the CPU chip

Paths on which electrical signals (a SERIES of bits) are Transmitted

Etched lines on PCI network card

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BUSESAccording to the information they contain, they can be categorized into

Address bus

Data bus

Control bus

Expansion Bus - carries data to and from the expansion slots

Local Bus - an expansion bus that connects directly to the CPU

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EXPANSION SLOTSExpansion Slot - a socket which holds a circuit board that increases the capability of the computer system

Expansion BoardExpansion Cards

Controller Cards

Adapter Cards

Interface Cards

Sound Card

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EXPANSION SLOTS

Inserting expansion board into expansion slot

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PORTS

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PORTS AND CONNECTORSConnectors

Male — have one or more pins

Female — have receptacles that match the pins — like electrical outlets

RJ Connector 1-pin BNC Connector

15-pin DB Connectors k satapathy

BAYSOpen areas inside the computer base, specifically designed to facilitate the installation of additional equipment

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POWER SUPPLY

Converts Wall Electricity to Lower Voltages

Convert 220V AC (in HK) to 5 to 12V DC to be used by different computer components

For power stability

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SOUND COMPONENTS

Speakers

Microphones

Music

Voice

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Power Supply

Ports and Connectors

Expansion board

Mother Board

Expansion Slots CPU

Memory

Hard Disk

Open Bay

Open Bay

Open Bay

CD-ROM

Floppy Drive

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STORAGE DEVICESSTORAGE DEVICES

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MAGNETIC DISK STORAGEMAGNETIC DISK STORAGE

Shutter

Paper Liner

Rigid Plastic Shell

Metal Hub

Plastic Disk

Magnetic Coating

3 1/2-inch Floppy disk (diskette)

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MAGNETIC DISK STORAGEMAGNETIC DISK STORAGE

Hard disksOne or more rigid platters

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MAGNETIC DISK STORAGEMAGNETIC DISK STORAGE

TrackSector

DiskSector

Tracks

This disk is dividedinto 18 sectors.s k satapathy

CD-ROM AND OPTICAL DISKSCD-ROM AND OPTICAL DISKSCD-ROM (compact disk read-only memory)

650 MB of information

DVD-ROM (digital versatile disk)

4.7 gigabytes

CD-R (compact disk-recordable)

Magneto-optical (MO)230 MB, 650 MB, 1.3 GB of information

support read and write operation.

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MAGNETIC TAPEMAGNETIC TAPEThin plastic ribbon

Sequential storage

Support read and write operation

reel-to-reel devices for large computer

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OTHER TYPES OF STORAGE DEVICES

OTHER TYPES OF STORAGE DEVICES

PC cardsVery small

Most often used with portable computers

Can store more than 300 MB of data

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SPECIAL-PURPOSE STORAGE DEVICESSPECIAL-PURPOSE STORAGE DEVICES

Smart Card

Optical Memory Card

Memory Button

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History of computerAbacusBlaise Pascal French Mathematician

Mech calculator in 1642

Charles Babbage 1830Automated Pascal’s model.

Herman invented Census Machine in 1887Punch cards were read by this m/c

1944 Electro Mechanical Computer Designed by using electro-magnetic relays

1946 ENIAC ( electro numeric integrator & cal )

18000 vaccum tubes, 30 tonnes,gen-purpose computerVon Neuman’s concept of Binary system

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A Brief History of Computers

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ABACUS

• 2000-500 BC

• Babylonians or Chinese

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Abacus

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Early Calculators

• 1614 John Napier, Napier’s Rods - multiply, divide, square roots

• 1623 Wilhelm Schickard, Calculating Clock reconstructed in 1960

• 1625 slide rule invented

• 1642 Blaise Pascal invented the Pascaline, the first “digital calulator”

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Napier’s Bones

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Schickard’s Calculator

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Slide Rule

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The Pascaline

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Early Caluclators

• 1822 Charles Babbage Mechanical computing machine. Too complicated to build until 1853

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Babbage’s “Difference Engine”

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Vacuum Tube

• 1906

• Lee Forest invented the “Electronic Valve”

• This made digital electronic computers possible

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Early Vacuum Tube

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First Generation computers

• 1939 - 1959

• Use vacuum tubes and wire circuits

• 1939 ABC computer completed, clock speed of 60 Hz, uses punch cards for secondary memory

• 1946 ENIAC 18,000 valves, used 25 KW of power, 100,000 calculations/second

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ABC Atanasoff-Berry Computer

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ENIAC

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ENIAC

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Transistors

• 1947

• Bell laboratories invent the transistor

• Smaller, cheaper, more reliable, less heat

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First Transistor

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Second Generation Computers

• 1959 - 1964

• Based on transistors and printed circuits

• Much smaller and less power consumption

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Integrated Circuit

• 1958

• Invented by Jack Kilby at Texas Instruments

• Integrates the functions of many transistors into one physical component

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First Integrated Circuit

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Third Generation Computers

• 1964 - 1972

• Based on integrated circuits, smaller than 2nd Generation

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Microprocessors

• 1971

• Intel released first microprocessor, the 4004

• Equivalent to 2,300 transistors, 4 bit data path, ran at 108 KHz

• Microprocessors are complex integrated circuits, capable of many different functions

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Intel 4004 Processor

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Intel 8088 circuitry

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Fourth Generation Computers

• 1972 -

• Based on microprocessors

• Utilize LSI (Large Scale Integration), and VLSI (Very Large Scale Integration)

• Smaller, faster, and more complex than 3rd Generation

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Fifth Generation Computers

• ????

• Will be much smaller and faster than 4th Generation

• Greatly increased data storage capability

• Will most likely have light, easily transportable display capabilities

• May be built into clothing

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Fifth Generation Computers

• Fifth Generation - Present and Beyond: Artificial IntelligenceFifth generation computing devices, based on artificial intelligence, are still in development, though there are some applications, such as voice recognition, that are being used today. The use of parallel processing and superconductors is helping to make artificial intelligence a reality. Quantum computation and molecular and nanotechnology will radically change the face of computers in years to come. The goal of fifth-generation computing is to develop devices that respond to natural language input and are capable of learning and self-organization.

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Physical Limits

• Chip designers are running up against the laws of physics. Ten years from now, chips will run at 30 GHz and complete a trillion operations per second. Unfortunately, with today's design technologies, those chips would be putting out the same amount of heat, proportionally, as a nuclear power plant.

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Physical Limits & CPUs

• We have “hit the wall” of physics in our CPU clock speeds

• Intel announced in 2004 that it would not attempt to make processors that run at speeds greater than 3.6 GHZ

• Future CPUs will have multiple “Cores” to increase performance and bandwidth

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Future Computers

• Few argue that the next generation of computers will be nearly invisible, meaning that they will blend in with everyday objects. Flexible ink-like circuitry will be printed onto plastic or sprayed onto various other substrates, such as clothes.

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Wearable Computers-Now

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Wearable Computers-future?

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Wearable Computers

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Wearables

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Characteristics of a Computer

• Speed: Computers provide the processing speed essential to our fast-paced society. The execution of an instruction, such as multiplying pay-rate with number of hours worked – are measured in milliseconds,microseconds, nanoseconds and Pico seconds. A computer speed is generally expressed in megahertz (MHz), millions of machine cycles per second. 

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• Accuracy: Results given by computer are accurate and consistent. Often mistakes attributed to computers are human errors.

• Flexibility: Above all, the computer provides fast access to information, process data, text, signals and generates reports in no time.

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Processing capability

It involves manipulating the symbols that represent things required by the users

Data and information

Data are represented by the symbols. After processing data information can be drawn

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• Handling the out put result

(a) storing and retrieving

(b) communicating and reproducing

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Computer processing operations

• Input output operations

• Text manipulation and calculation operations

• Logic/ comparison operations

• Storage and retrieval operations

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Memory capability

• Computer system has the ability of total and instant recall of data and an almost unlimited capacity to store these data

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COMPUTER GENERATIONS

1. VACUUM TUBES: 1946-1959

2. TRANSISTORS: 1957-1963

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COMPUTER GENERATIONS

1. VACUUM TUBES: 1946-1959

2. TRANSISTORS: 1957-1963

3. INTEGRATED CIRCUITS: 1964-1979

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COMPUTER GENERATIONS

1. VACUUM TUBES: 1946-1959

2. TRANSISTORS: 1957-1963

3. INTEGRATED CIRCUITS: 1964-1979

4. VERY LARGE-SCALE INTEGRATED (VLSI) CIRCUITS: 1980- PRESENT

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SUPERCOMPUTERTERAFLOP: TRILLION CALCULATIONS/SECOND

• HIGHLY SOPHISTICATED

• COMPLEX COMPUTATIONS

• FASTEST CPUs

• LARGE SIMULATIONS

• STATE-OF-THE-ART COMPONENTS

• EXPENSIVE

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MAINFRAME

• LARGEST ENTERPRISE COMPUTER

• 5O MEGABYTES TO OVER ONE GIGABYTE RAM

• COMMERCIAL, SCIENTIFIC, MILITARY APPLICATIONS

• MASSIVE DATA

• COMPLICATED COMPUTATIONS

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MIPS: Millions of Instructions per secondMIPS: Millions of Instructions per second

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MINICOMPUTER

• MIDDLE-RANGE

• 10 MEGABYTES TO OVER ONE GIGABYTE RAM

• UNIVERSITIES, FACTORIES, LABS

• USED AS FRONT-END PROCESSOR FOR MAINFRAME

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• DESKTOP OR PORTABLE• 64 KILOBYTES TO OVER 128 MEGABYTES

RAM• PERSONAL OR BUSINESS COMPUTERS• AFFORDABLE• MANY AVAILABLE COMPONENTS• CAN BE NETWORKED

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MICROCOMPUTER

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Computer Generations

1st GENERATION 1940-52 (valves & vaccum tubes )

2nd GENERATION 1952-64 (trans,diodes,flip flops)

3rd GENERATION 1964-71 (MSI)

4th GENERATION 1971 (VLSI,processor)

5th GENERATION (AI,speech/speaker,recognisation knowledge bases adapt

through experience)

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First generation

• Vacuum time circuit• Continuous maintenance required• Punch card and paper tape storage• Machine and symbolic language programming• Different computers for scientific and business applications• Batch processing• Generated considerable heat• Poor reliability• Limited internal storage capacity• First commercial computer to be used• Slow input out put operations• Examples are ENIAC, EDSAC and UNIVAC

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Second generation

• Transistor circuit • Magnetic core primary storage• Secondary storage on tapes• Greater reliability and speed• Transistor replaced tubes• Reduced generated heat• Smaller and more reliable• Faster than first gen computers• Required less power to operate• Development of magnetic disk storage• FORTRAN and COBOL were used• Examples are IBM 700, ATLAS and ICL 1901

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Third generation

• Integrated circuit of thousands of transistors and other electronic components on a silicon crystal

• Increased miniaturisation , speed and reliability• Development of mini computers• Transistors replaced by ICs• Magnetic disk secondary storage• On line real time processing• Multiprograming operating system• Faster than previous generation computers• Improved input and output devices• Concept of multi programing was used• Better storage devices• Examples are IBM/360/370 .

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Fourth generation

• Large scale and VLSI circuits• Rise in hardware cost• Semi conductor primary storage• Development of Micro and personnel computer• Increased cost of software• Data base management system• Application development by users• User friendly software• Graphics terminals• Compact size but faster speed• Microprocessor used

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TYPES OF COMPUTERS

Main Frames

Mini Frames

Micros

Super Computer

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Representation of data inside Computer

Logic High or Logic Low

Voltage high & low

Binary System (bit = 0 or 1)

Combination of bits represnets a character/numeric

8 bits make a BYTE

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Computer Specifications

Memory

Storage

Speed

Data bus

Resolution

Multimedia

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SoftwareOS

unix, win NT, dos, win 95 etc

Languages

c/c++, basic, pascal, lisp etc

Applications s/w

HLL

ALL

MLL

Kernel

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HARDWARE• Ram’s friend John had a daughter who

started going to college and wanted to buy a computer. Ram spent a while on the phone answering questions, and Ram thought she understood the fundamentals pretty well, until she asked: "Which is better, hardware or software?"

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