Transcript Introduction to Computers

Introduction to Computers
Structured Computer Organization
Lecture #1
Jahan Zeb
Introduction to Computers
 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.
Lecture #1, Structured Computer Organization
Devices that comprise a computer system
Speaker
(output)
System unit
(processor, memory…)
Printer
(output)
Monitor
(output)
Storage devices
(CD-RW, Floppy, Hard
disk)
Scanner
(input)
Mouse
(input)
Keyboard
(input)
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Compare a computer ,Typical workshop
features
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Materials
Tools
Working Area
Storage
Measurements
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Workshop
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Materials: Wood
Tools: Hammer, screw driver, drill…
Work area: Worktable
Storage: Cabinet
Measurements Yards, feet, inches, meters,
centimeters, millimeters
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Compare a computer, Kitchen
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Materials: Food
Tools: Stove, mixer, spoon…
Work Area: Counter, cutting board, bowl…
Storage: Refrigerator, cabinet…
Measurements: Cups, tablespoons, teaspoons etc
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Computers
 How does this apply to computers?
 You will find materials, tools, work area,
storage, and measurements
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Computer Materials
 Information
 Words
 Numbers
 Pictures
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Computer Tools
 Two kinds:
 Hardware
 Physical parts to computer
 Software
 All information or data
 This slide show for example
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Computer Working Area
 The work area of a computer is called a window.
 The figure shows a typical window.
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Computer Storage
 Two main types:
 Memory (RAM)
 Data Storage (CD, DVD, Flash Drive)
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Measuring Information
 Bytes
 One character takes up about one Byte.
 An email takes up a few (thousand bytes) Kilobytes
(thousands of bytes)
 A picture may take up Megabytes (millions of
bytes)
 All the information on a computer may run into
Gigabytes (billions of bytes)
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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
computer 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 (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 (CPU)
 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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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 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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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 thousands of GBs.
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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 650-700 MB of data
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Flash Drive
 Most recent widely used storage system
 Very portable, often worn like jewelry
 128MB to GBs
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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 XP/Vista/7 are widely used
graphical operating systems. DOS (Disk Operating
System) is an older but still rarely 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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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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What is convenient?
People want to do X
Computers can only do Y
Problem Resolution
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Milestones in computer Architecture
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Evolution of modern digital computers
Most have been long forgotten
Few have significance
Generations
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Zeroth-Mechanical computers
First- Vacuum Tubes
Second-Transistors
Third-Integrated Circuits (IC)
Fourth-Very Large Scale Integration (VLSI)
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The Zeroth Gen-Mechanical Computers
(1642-1945)
 Working calculator-French Scientist
 Blaise Pascal, Pascal language
 Addition, subtraction
 30 yrs later, Baron Gottfried
 Multiplication, Division
 Leibniz, four function calculator
 Charles Babbage, Difference Engine
 Single Algorithm
 Output punched, copper plates
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Contd…
 Analytical Engine
 Store (Memory)
 Mill (Computation unit)
 Input (Punched card
reader)
 Output (Punched)
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The First Gen-Vacuum Tubes (19451955)
 Vacuum tubes are glass tubes with circuits inside
 Alan Turing, COLOSSUS
 World’s first electronic digital computer
 ENIAC (Electronic Numerical Integrator and Computer)
 18,000 vacuum tubes, 1500 relays
 30 tons, 140kw of power
 Capable of 20 Registers
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(ENIAC)
Von Neumann Machine
 First stored programmed computer, basis of
modern digital computers.
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Memory
Arithmetic and Logic Unit
Control Unit
I/O Equipment
Inside ALU , Special 40bit register called
Acuumulator
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Von Neumann Machine
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The Second Gen-Transistors
(1955-1965)
 First Transistor
 Uses Silicon
 Developed in 1948, used in
1956
 won a Nobel prize
 on-off switch
 First Transistorised computer
known as TX-0
(Transistorised eXperimental
computer 0)
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The Third Gen- Integrated Circuits
(1965-1980)
 Third Generation Computers used Integrated
Circuits (chips).
 Integrated Circuits are transistors, resistors, and
capacitors integrated together into a single “chip”
 Operating System (OS)
 Getting smaller, cheaper
 IBM, Intel Products
 Innovation of Multiprogramming
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The First Microprocessor – 1971
 Intel 4004
Microprocessor
 The 4004 had 2,250
transistors
 108Khz
 Called “Microchip”
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What is a Microchip?
 Very Large Scale Integrated Circuit (VLSIC)
 Transistors, resistors, and capacitors
 4004 had 2,250 transistors
 Pentium IV has 42 MILLION transistors
 Each transistor 0.13 microns (10-6 meters)
 Getting smaller and smaller, but we are still
using microchip technology
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Technological/Economic Progress
Moore’s Law
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The Computer Spectrum
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Birth of Personal Computers - 1975
 256 byte memory (not
Kilobytes or
Megabytes)
 2 MHz Intel 8080 chips
 Just a box with flashing
lights
 cost $395 kit, $495
assembled.
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Personal Computer
This circuit
board is at the heart
of every personal
computer. This
figure is a
photograph of the
Intel D875PBZ
board. The
photograph is
copyrighted by the
Intel Corporation,
2003 and is used by
permission.
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Others
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Disposable Computers
Microcontrollers
Embedded Computers
Game Computers
Personal Computers
Servers
Collections of Workstations
COW (Cluster of Workstations)
Mainframes
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Pentium
 Intel 8086,8088,80286,80486
 Cache Memory
 Used to hold most commonly used memory
data close to CPU( Central Processing Unit)
 MMX ( Multimedia Extension)
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Moore’s Law for CPU chips
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