Lecture#2
YASMIN AFZAAL
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Exploring Computers and their Uses:
“Computers are everywhere”
• In our family car, in home appliances and even in
our alarm clock
• Majority of business now use computerized
equipment
• Most companies are networked internally and
externally
• More than half of all homes in the united states
have at least one computer
• Workers who once had little use for technology
now interact with computers almost every
minute of the work day.
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Cont..
• A computer controlling the automatic
transmission in a car. Any radio or CD player
with a digital display contains a computer of
its own.
Fig: Car navigation System
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The computer defined
• A computer is an electronic device that
processes data, converting it information that
is useful to people.
• Any type of computer is controlled by
programmed instructions, which give the
machine a purpose and tell it what to do.
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TYPES OF COMPUTERS
• Two types of computers
– Digital computers
– Analog computers
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Cont..
• Analog computers are used for quantities for
which the exact values are not always
necessary such as temperature and speed
• Digital computers are used for numbers which
require exact values, for example, the
calculations which are carried out while
constructing a bridge and other operations.
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Digital computers:
• Are work “ by the numbers”
• Break all types information into tiny units and use
numbers to represent those pieces of information.
• Digital computer, any of a class of devices
capable of solving problems by processing
information in discrete form.
• It operates on data, including magnitudes, letters,
and symbols, that are expressed in binary code—
i.e., using only the two digits 0 and 1.
Cont..
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Cont..
• Analog computers:
– A lesser known computers
– Earliest computers were analog systems
– Early analog computers were mechanical devices
weighing several tons and using motors and gears
to perform calculations
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Fig: Vannevar Bush (1890–1974) with his differential analyzer
Differential Analyzer – An Analog computer
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A simple kind of analog computer
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• Computer can be categorized
– by their use
• used by one person
• Used by groups of people
• Not used by people at all
– by their power
• Speed at which they operate
• Types of tasks they can handle
– By price
– By types of hardware
– By kind of software
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Computers for individual users
• Computer meant for single accessibility that is
used by only one user at a time e.g.
Computers in lab
• Also called microcomputer
• Smallest computers created for people
• Connected to create networks
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Cont..
• Desktop computers
• Workstations
• Notebook computers
• Tablets computer
• Handheld computers
• Smart phones
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Desktop Computers
• Most common type of computer
• A PC design to sit on a desk or table
• In schools, homes and offices.
• Today’s desktop are more powerful can be
used to communicate, produce music, edit
photographs and videos, play games and much
more.
• From preschool to nuclear physicists
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Design of desktop computers
Fig: tower design system unit can be placed
on floor or desk
Fig: traditional design , with
monitor stacked on top of the
system unit
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Work stations
• A workstation is a special computer designed for
technical or scientific applications. Intended
primarily to be used by one person at a time,
they are commonly connected to a local area
network and run multi-user operating systems.
• Specialized, single user computer
• More features and power than desktop PC
• Used by engineers, scientists, animators
• Large high resolution monitor, accelerated
graphics handling capabilities, engineering
design,video editing
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Cont..
Fig: Office work stations
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Note book Computers
• Have power and features of desktop PCs but are
light and portable
• Shape of 8.5-by-11 inch
• Fit inside a brief case
• Also called laptop computers
• Operate on special batteries
• Weightless than 8 pounds even than three
pounds
• Having thin monitor and keyboard
• Also called mobile computers
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Cont..
• Docking station is a hardware device that
allows portable computers to connect with
other devices with little or no effort.
• enable users with a laptop computer to
convert it into a desktop computer when at
the office or at home.
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Cont..
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Tablets PC
• Functionality of note book PC but are more lighter
• Accept input from a special pen -Stylus or a digital pen
• Used to write directly on the screen
• Built-in microphones and special software accept input
from user voice
• Few models with fold-out keyboard can be transferred
to notebook PC
• Can be connected to keyboard and a full-sized monitor
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Handheld PCs
• Small enough to fit in hands
• Popular type of handheld computer
– PDA(Personal digital assistance)
• Not larger than a small appointment book
• Built-in keyboard or microphones
• Access internet via wireless connection
• Some models have features such as cellular telephones,
cameras, music players &GPS
• Used for
– Taking notes
– Displaying telephones numbers & Addresses
– Keeping track of dates and agenda
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Smart phones
• a mobile phone that performs many of the
functions of a computer, typically having a
touchscreen interface, Internet access, and an
operating system capable of running
downloaded apps.
Fig: Smart phone with miniature keyboard 26

Computers for organizations
• Handled needs of many users at the same
time i.e. In schools, business
• Each user interact with his or her own device
• Freeing people from having to wait for their
turn for a single keyboard and monitor
• Support thousands of users at the same time
from thousand of miles away
• Some are for special purpose and mostly for
general purpose
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Network servers
• Individual users with desktop computers
connected to one or more centralized
computers called network servers
• It is powerful computer with special software
equipment
• Clusters or server farms (dozens or hundreds
of individual servers working together)
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Cont..
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Mainframe computers
• Large powerful systems, handled processing
needs of thousands of users at a given time
• Used in large organizations i.e. insurance
company and banks
• Where many people frequently need to use the
same data
• In traditional mainframe environment user access
the mainframe resources through a device called
terminal
• dumb terminals and intelligent terminals
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Cont..
• Intelligent terminal
– Perform some processing operations
– No storage
• Dumb terminal
– Do not store/process data
– Simply an input/output device
• Can use PCs to access mainframe.
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Cont..
• Most mainframe system designed to handle specific
tasks
• Department of a motor vehicles
– Storing information about
» Drivers
» Vehicles
» Drivers’ licenses
• Airline’s website
– To reserve a seat on a flight conduct
a transaction with mainframe computer
Fig: Often housed alone in
special rooms away from
their users
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Minicomputers
• Released in 1960s
• Small sized
• Also called midrange computers (capabilities
between personnel and mainframe computers)
• Handled more input/output than personal
computers
• Used in scientific and engineering computations,
business-transaction processing, file handling,
and database management
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Super computer
• Largest and powerful computers
• Process huge amount of data
• Perform more than one trillion calculations
per second
• Housed thousands of processors
• Used for handling complex problems
– Forecasting weather
– Nuclear fission
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Fig: Super computer
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Parts of a computer system
• Hardware
• Software
• Data
• User
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Software
• Software is a program that enables
a computer to perform a specific task
• software is instructions that can be stored and
ran by hardware.
• Application software
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Hardware
• Computer hardware are the physical parts
or components of a computer, such as the
monitor, keyboard, computer data storage,
graphic card, sound card and motherboard.
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Data
• Computer data is information processed or
stored by a computer. This information may
be in the form of text documents, images,
audio clips, software programs, or other types
of data. Computer data may be processed by
the computer's CPU and is stored in files and
folders on the computer's hard disk.
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Cont..
• These processes work together and repeat
over and over.
• Input—entering data into the computer.
• Processing—performing operations on the
data.
• Storage—saving data, programs, or output for
future use.
• Output—presenting the results.
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Essential computer hardware
• Processor
• Memory
• Input/output
• storage
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Processor
• Brain of computer
• It is in motherboard
• A central processing unit is the electronic
circuitry within a computer that carries out
the instructions of a computer program by
performing the basic arithmetic, logical,
control and input/output operations specified
by the instructions.
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Memory
• Computer memory is any physical device
capable of storing information temporarily or
permanently.
• RAM (random access memory)
• ROM (read only memory)
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RAM
• Random-access memory is a form of
computer data storage that stores data and
machine code currently being used.
• Hold data and program instructions while the
CPU works with them
• Also called read/write memory
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ROM
• ROM is "built-in" computer memory containing data
that normally can only be read, not written to.
• Non-volatile memory never loses its contents
• Contains info about computer hardware
• ROM contains the programming that allows your
computer to be "booted up" or regenerated each time
you turn it on.
• . Unlike a computer's random access memory (RAM),
the data in ROM is not lost when the computer power
is turned off. The ROM is sustained by a small long-life
battery in your computer.
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Cont..
• Tremendous effect on computer speed and
power
• More RAM a computer has more tasks it can
do and faster it can perform tasks
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INPUT/OUTPUT DEVICES
• INPUT DEVICES
• Input Devices:
• a) Graphics Tablets
• b) Cameras
• c) Video Capture
Hardware
• d) Trackballs
• e) Barcode reader
• f) Digital camera
• g) Gamepad
h)Joystick
i) Keyboard
j) Microphone
k) Mouse
m) Scanner
n) Webcam
o) Touchpads
p) Pen Input
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Output devices
• Monitor (LED, LCD, CRT etc.)
• Printers (all types)
• Plotters
• Projector
• Speaker(s)
• Head Phone
• Visual Display Unit
• Film Recorder
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Both…
• Both Input–OutPut Devices:
• Modems
• Network cards
• Touch Screen
• Headsets (Headset consists of Speakers and
Microphone.
– Speaker act Output Device and Microphone act as Input device)
• Facsimile (FAX)
– It has scanner to scan the document and also have printer to Print
the document
• Audio Cards / Sound Card
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Storages devices
• a piece of computer equipment on which
information can be stored.
• Magnetic storage
• Optical storage
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Cont..
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• Optical storage is the storage of data on an
optically readable medium. Data is recorded
by making marks in a pattern that can be read
back with the aid of light, usually a beam of
laser light precisely focused on a
spinning optical disc.
Optical storage devices
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Magnetic storage
• Magnetic storage or magnetic recording is
the storage of data on a magnetized
medium. Magnetic storage uses different
patterns of magnetisation in a magnetisable
material to store data and is a form of non-
volatile memory.
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Material
• BOOK:
– Introduction to Computers
Peter Norton
Published by McGraw Hill
– lesson 1A
 Exploring computer and their uses
– Lesson 1B
• Looking inside the computer system
• SLIDES:
– Uploaded on portal
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