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COMPUTERS -INTRODUCTION. What Is A Computer ?.

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what is a computer

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
Devices that comprise a computer system

Monitor (output)

Speaker (output)

System unit

(processor, memory…)

Printer (output)

Storage devices

(CD-RW, Floppy, Hard disk, zip,…)

Mouse (input)

Scanner (input)

Keyboard (input)

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what does a computer do

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
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
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
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
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
Input Devices
  • Keyboard.
  • Mouse.

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the keyboard

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

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

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

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

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

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

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 disks

Floppy Disks

A 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
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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slide20
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
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
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

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

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

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
  • 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 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
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 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
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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computer1
Computer
  • An electronic device
  • Can store and process data
  • Speed and accuracy
  • Access desired data
  • Not a master but a slave

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personal computer
Personal Computer

Monitor

CPU

Keyboard

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elements of a computer system
Computer components

Input devices

Output devices

Storage devices

ELEMENTS OF A COMPUTER SYSTEM

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structure of computer
Structure of Computer

central processing unit

Storage

Memory

Control

Unit

Output

Device

Input

device

Arithmatic

& Logic

Unit

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microprocessor and the cpu
MICROPROCESSORAND THE CPU
  • Arithmetic/Logic Unit
    • Arithmetic 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

COMPONENTS OF THE SYSTEM UNIT

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motherboard
MOTHERBOARD
  • Main 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 Jokes

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microprocessor and the cpu1
MICROPROCESSORAND THE CPU
  • Microprocessor- contains the central processing unit (CPU)

Top View

Bottom View

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microprocessor and the cpu2
MICROPROCESSORAND THE CPU
  • System Clock
    • Controls 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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memory1
MEMORY
  • Every computer has the same available memory: too little.
          • Ken Skier, 1981

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memory2
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
RANDOM ACCESS MEMORY
  • Main Memory
  • volatile — gets erased when the computer is turned off

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memory3
MEMORY
  • RAM
    • RAM 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
BUSES
  • Paths on which electrical signals (a SERIES of bits) are Transmitted
  • Wires, OR
  • Etched lines on the circuit board, OR
  • Within the CPU chip

Etched lines on PCI network card

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buses1
BUSES
  • According 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 slots
EXPANSION SLOTS
  • Expansion Slot - a socket which holds a circuit board that increases the capability of the computer system
  • Expansion Board
    • Expansion Cards
    • Controller Cards
    • Adapter Cards
    • Interface Cards

Sound Card

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expansion slots1
EXPANSION SLOTS
  • Inserting expansion board into expansion slot

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slide48
PORTS

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ports and connectors
PORTS AND CONNECTORS
  • Connectors
    • 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 Connector

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slide50
BAYS
  • Open areas inside the computer base, specifically designed to facilitate the installation of additional equipment

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power supply
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
SpeakerSOUND COMPONENTS
  • Speakers
  • Microphones
  • Music
  • Voice

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slide53
Floppy Drive

Power Supply

CD-ROM

Open Bay

Ports and Connectors

Open Bay

Open Bay

Expansion board

Hard Disk

Memory

Expansion Slots

Mother Board

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CPU

storage devices1
STORAGE DEVICES

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magnetic disk storage
MAGNETIC DISK STORAGE
  • 3 1/2-inch Floppy disk (diskette)

Shutter

Rigid Plastic Shell

Paper Liner

Metal Hub

Plastic Disk

Magnetic Coating

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magnetic disk storage1
MAGNETIC DISK STORAGE
  • Hard disks
    • One or more rigid platters

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magnetic disk storage2
MAGNETIC DISK STORAGE

Track

Sector

Disk

Sector

Tracks

This disk is divided

into 18 sectors.

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cd rom and optical disks
CD-ROM AND OPTICAL DISKS
  • CD-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 tape
MAGNETIC TAPE
  • Thin plastic ribbon
  • Sequential storage
  • Support read and write operation

reel-to-reel devices for large computer systems

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other types of storage devices
OTHER TYPES OF STORAGE DEVICES
  • PC cards
    • Very small
    • Most often used with portable computers
    • Can store more than 300 MB of data

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special purpose storage devices
SPECIAL-PURPOSE STORAGE DEVICES

Memory Button

Smart Card

Optical Memory Card

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history of computer
History of computer
  • Abacus
  • Blaise Pascal French Mathematician
    • Mech calculator in 1642
  • Charles Babbage 1830
    • Automated Pascal’s model.
  • Herman invented Census Machine in 1887
    • Punch 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 computer
  • Von Neuman’s concept of Binary system

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abacus
ABACUS
  • 2000-500 BC
  • Babylonians or Chinese

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abacus1
Abacus

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early calculators
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
Napier’s Bones

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slide rule
Slide Rule

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the pascaline
The Pascaline

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early caluclators
Early Caluclators
  • 1822 Charles Babbage Mechanical computing machine. Too complicated to build until 1853

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vacuum tube
Vacuum Tube
  • 1906
  • Lee Forest invented the “Electronic Valve”
  • This made digital electronic computers possible

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early vacuum tube
Early Vacuum Tube

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first generation computers
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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eniac
ENIAC

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eniac1
ENIAC

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transistors
Transistors
  • 1947
  • Bell laboratories invent the transistor
  • Smaller, cheaper, more reliable, less heat

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first transistor
First Transistor

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second generation computers
Second Generation Computers
  • 1959 - 1964
  • Based on transistors and printed circuits
  • Much smaller and less power consumption

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integrated circuit
Integrated Circuit
  • 1958
  • Invented by Jack Kilby at Texas Instruments
  • Integrates the functions of many transistors into one physical component

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third generation computers
Third Generation Computers
  • 1964 - 1972
  • Based on integrated circuits, smaller than 2nd Generation

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microprocessors
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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fourth generation computers
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
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 computers1
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
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
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
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
Wearable Computers

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wearables
Wearables

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characteristics of a computer
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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slide99
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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slide100
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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slide102
Handling the out put result

(a) storing and retrieving

(b) communicating and reproducing

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computer processing operations
Computer processing operations
  • Input output operations
  • Text manipulation and calculation operations
  • Logic/ comparison operations
  • Storage and retrieval operations

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memory capability
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
COMPUTER GENERATIONS

1. VACUUM TUBES: 1946-1959

2. TRANSISTORS: 1957-1963

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computer generations1
COMPUTER GENERATIONS

1. VACUUM TUBES: 1946-1959

2. TRANSISTORS: 1957-1963

3. INTEGRATED CIRCUITS: 1964-1979

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computer generations2
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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supercomputer teraflop trillion calculations second
SUPERCOMPUTERTERAFLOP:TRILLION CALCULATIONS/SECOND
  • HIGHLY SOPHISTICATED
  • COMPLEX COMPUTATIONS
  • FASTEST CPUs
  • LARGE SIMULATIONS
  • STATE-OF-THE-ART COMPONENTS
  • EXPENSIVE

*

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mainframe
MAINFRAME

MIPS: Millions of Instructions per second

  • LARGEST ENTERPRISE COMPUTER
  • 5O MEGABYTES TO OVER ONE GIGABYTE RAM
  • COMMERCIAL, SCIENTIFIC, MILITARY APPLICATIONS
  • MASSIVE DATA
  • COMPLICATED COMPUTATIONS

*

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minicomputer
MINICOMPUTER
  • MIDDLE-RANGE
  • 10 MEGABYTES TO OVER ONE GIGABYTE RAM
  • UNIVERSITIES, FACTORIES, LABS
  • USED AS FRONT-END PROCESSOR FOR MAINFRAME

*

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microcomputer
MICROCOMPUTER
  • 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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computer generations3
Computer Generations
  • 1st GENERATION 1940-52(valves & vaccum tubes )
  • 2ndGENERATION 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
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
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
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
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
TYPES OF COMPUTERS
  • Main Frames
  • Mini Frames
  • Micros
  • Super Computer

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representation of data inside computer
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
Computer Specifications
  • Memory
  • Storage
  • Speed
  • Data bus
  • Resolution
  • Multimedia
  • Add on cards

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software
Software
  • OS
    • 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
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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