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Chapter One
Introduction to Computer
Computer
A computer is an electronic device, operating under the control of instructions stored
in its own memory that can accept data (input), process the data according to specified
rules, produce information (output), and store the information for future use1
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Hardware:
Computer hardware is the collection of physical elements that constitutes a computer
system
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all of
which are physical objects that can be touched
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Microsoft Office 2013 Introductory
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IT3
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tutorialspoint
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htm
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http://en
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org/wiki/Computer_hardware
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Input Devices
Input device is any peripheral (piece of computer hardware equipment to provide data
and control signals to an information processing system such as a computer or other
information appliance
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Most common are keyboard and mouse

Example of Input Devices:1
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Touch screen
7
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Graphics Tablets
13
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Barcode reader
19
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Mouse (pointing device)
5
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MIDI keyboard
11
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Microphone
17
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Electronic Whiteboard

3
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Webcam
9
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Pen Input
15
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Joystick
21
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Generally standard Keyboard
has 104 keys
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It is responsible for all functions and processes
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The CPU is comprised of three main parts :
* Arithmetic Logic Unit (ALU): Executes all arithmetic and logical operations
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Logical operation like compare numbers, letters, or special characters
* Control Unit (CU): controls and co-ordinates computer components
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Read the code for the next instruction to be executed
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Increment the program counter so it points to the next instruction
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Read whatever data the instruction requires from cells in memory
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Provide the necessary data to an ALU or register
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If the instruction requires an ALU or specialized hardware to complete, instruct
the hardware to perform the requested operation
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Primary Memory:1
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It is volatile in nature, which means
that data will be erased once supply to the storage device is turned off
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RAM is considered "random access" because you can access any memory
cell directly if you know the row and column that intersect at that cell
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ROM (Read Only Memory): ROM is a permanent form of storage
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ROM devices
do not allow data stored on them to be modified
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Hard drive (HD): A hard disk is part of a unit, often called a "disk drive," "hard drive," or "hard
disk drive," that store and provides relatively quick access to large amounts of data on an
electromagnetically charged surface or set of surfaces
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Optical Disk: an optical disc drive (ODD) is a disk drive that uses laser light as part of the process
of reading or writing data to or from optical discs
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Compact discs,
DVDs, and Blu-ray discs are common types of optical media which can be read and recorded by
such drives
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There are three main types of optical media: CD,
DVD, and Blu-ray disc
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4 GB of data
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This storage capacity is a clear advantage over the floppy disk storage media (a
magnetic media), which only has a capacity of 1
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3
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A Flash disks have no mechanical platters or access
arms, but the term "disk" is used because the data are accessed as if they were on a hard drive
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Output devices
An output device is any piece of computer hardware equipment used to communicate
the results of data processing carried out by an information processing system (such
as a computer) which converts the electronically generated information into humanreadable form
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Monitor
3
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Plotters
7
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LCD Projection Panels
4
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Speaker(s)

Note Basic types of monitors are a
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B
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c
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Printer types: 1-Laser Printer
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3-Dot Matrix Printer

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Software
Software is a generic term for organized collections of computer data and instructions,
often broken into two major categories: system software that provides the basic nontask-specific functions of the computer, and application software which is used by
users to accomplish specific tasks
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System software is responsible for controlling, integrating, and managing the
individual hardware components of a computer system so that other software and
the users of the system see it as a functional unit without having to be concerned
with the low-level details such as transferring data from memory to disk, or
rendering text onto a display
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B
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Application software may consist of a single program, such
as an image viewer; a small collection of programs (often called a software
package) that work closely together to accomplish a task, such as a spreadsheet or
text processing system; a larger collection (often called a software suite) of related
but independent programs and packages that have a common user interface or
shared data format, such as Microsoft Office, which consists of closely integrated
word processor, spreadsheet, database, etc
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Comparison Application Software and System Software
System Software
Computer software, or just software is a
general term primarily used for digitally stored
data such as computer programs and other
kinds of information read and written by
computers
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Example:

Interaction:

Dependency:

1) Microsoft Windows
2) Linux
3) Unix
4) Mac OSX
5) DOS
Generally, users do not interact with system
software as it works in the background
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Application Software
Application software, also known as an
application or an "app", is computer software
designed to help the user to perform specific
tasks
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Application software cannot run without the
presence of the system software
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Computers use these little bits, which are composed of ones
and zeros, to do things and talk to other computers
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This two
number system, is called a “binary number system” since it has only two
numbers in it
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Computer Storage units
Bit
Kilobyte
Megabyte
Gigabyte
Terabyte

BIT
KB
MB
GB
TB

0 or 1
1024 bytes
1024 kilobytes
1024 megabytes
1024 gigabytes

Size example
• 1 bit - answer to an yes/no question
• 1 byte - a number from 0 to 255
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• 4 KB: about one page of text
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• 3 MB - a three minute song (128k bitrate)
• 650-900 MB - an CD-ROM
• 1 GB -114 minutes of uncompressed CD-quality audio at 1
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The speed of CPU is known as Computer
Speed
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In
addition to the microprocessor, a personal computer has a keyboard for entering
data, a monitor for displaying information, and a storage device for saving data
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A workstation is like a personal
computer, but it has a more powerful microprocessor and a higher-quality
monitor
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• mainframe : A powerful multi-user computer capable of supporting many hundreds
or thousands of users simultaneously
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Laptop and Smartphone Computers
LAPTOP: A laptop is a battery or AC-powered personal computer that can be easily
carried and used in a variety of locations
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However,
some laptops, such as netbooks, sacrifice some functionality in order to be
even more portable
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Netbooks are often cheaper than laptops or desktops
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Mobile Device: A mobile device is basically any handheld computer
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Some mobile devices are more powerful, and they allow you to do many of

***http://www
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net/teaching/survival/handouts/pcwebopedia
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These include
tablet computers, e-readers, and smartphones
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However, they provide a very different computing experience
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Instead, the entire screen is touch-sensitive, allowing you to type on a virtual
keyboard and use your finger as a mouse pointer
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For many
people, a "regular" computer like a desktop or laptop is still needed in order
to use some programs
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Smartphones: A smartphone is a powerful mobile phone that is designed to run a
variety of applications in addition to phone service
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Data, Information and Knowledge
Data: Facts and figures which relay something specific, but which are not organized
in any way and which provide no further information regarding patterns, context, etc
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"
Information: For data to become information, it must be contextualized, categorized,
calculated and condensed
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It may convey a trend in the environment, or perhaps indicate
a pattern of sales for a given period of time
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Knowledge: Knowledge is closely linked to doing and implies know-how and
understanding
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The content of the human mind can be classified into four categories:
1
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Information: data that are processed to be useful; provides answers to "who", "what",
"where", and "when" questions
3
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Wisdom: evaluated understanding
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A brief overview of these characteristics are
• Speed: The computer can process data very fast, at the rate of millions of instructions
per second
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For example, calculation and generation of salary slips of thousands of
employees of an organization, weather forecasting that requires analysis of a
large amount of data related to temperature, pressure and humidity of various
places, etc
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For example, the computer
can accurately give the result of division of any two numbers up to 10 decimal
places
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It can perform long and complex calculations with the same speed and
accuracy from the start till the end
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A limited amount of data can
be stored, temporarily, in the primary memory
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• Versatility: Computer is versatile in nature
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At one moment you can use the computer to prepare a letter
document and in the next moment you may play music or print a document
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Computer can only perform tasks that
it has been programmed to do
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It executes
instructions as specified by the user and does not take its own decisions
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For
example, a virus might attach itself to a program such as a spreadsheet program
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•E-mail viruses: An e-mail virus travels as an attachment to e-mail messages, and
usually replicates itself by automatically mailing itself to dozens of people
in the victim's e-mail address book
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•Trojan horses: A Trojan horse is simply a computer program
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Trojan horses have no way to replicate
automatically
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A copy of the worm scans the network for another
machine that has a specific security hole
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What are some tips to avoid viruses and lessen their impact?*
 Install anti-virus software from a reputable vendor
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 In addition to scanning for viruses on a regular basis, install an "on access"
scanner (included in most anti-virus software packages) and configure it to start
each time you start up your computer
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 Use a virus scan before you open any new programs or files that may contain
executable code
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 If you are a member of an online community or chat room, be very careful
about accepting files or clicking links that you find or that people send you
within the community
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) on disc so that in the event of a virus infection, you do not lose
valuable work
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howstuffworks
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htm
*http://www
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gov/publications/virus-basics

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