Fundamentals of Computing

FUNDAMENTALS OF
COMPUTING
By JOEL AMENYA K.
Tel:0724269229
Email: joamesh@gmail.com,
joamesh@hotmail.com for assignemnt

Introduction
O What is a computer?
O It is an electronic programmable machine
that accepts data as input process it and
give output in form information.
O It is composed of two major components:
O Hardware and
O software.
06/27/13
Fundamentals of Computing by
Joel Amenya
2

Common Computer terms
O Hardware: the physical tangible parts or
components of a computer system
O Software: these are sets of instruction
(programs) used to direct the operation of a
computer. such as word process, manage
databases, play games, etc
O Softcopy: This is unprinted information/data or
instructions in the computer.
O Hardcopy: means printed output, or
information that has been printed on paper
stationary.
06/27/13Fundamentals of Computing by Joel Amenya 3

Common Computer terms
cont’d
O Peripheral: electronic equipment
connected by cable to the computer.
They are used to increase the
functionality of the computer. E.g.
printer, scanner
O Data: Raw facts of information that
have not been processed thus are not
meaningful to the user.
O Information: This processed data that
is meaningful to the user.

Computer evolution/History
O Computer History and Generations
O Abacus computers - These were the first computers
cable of only doing addition and subtraction
O Pascaline - This was a mathematical calculator which
performs addition and subtraction
O G.W Leinbiz - Stepped up performance and uses punch
card for storage of information, they had got additional
function besides addition and subtraction, and also
performs square root functionality
O Charles Babbage - Uses engine and could compute
data and store data and information. They were analytical
machine which works as the present computers

Computer Generations
First Generation Computers
O Characteristics of 1st
generation Computers
1946 - 1959
O These computers used vacuum tube for data processing
and storage.
O They had a memory size of 20bytes speed of 5mbps (very
small).
O They produced a lot of heat.
O These computers were unreliable and could not work fast
with a lot of data.
O They uses punch card for data storage.
O The programmer were machine dependent.
O First generation consume a lot of power.

Second Generation of
Computer. 1959-1964
O Were capable of translating, process and store
data
O Had got memory size of 32bytes speed of
10mbps
O Were reliable compared to first generation
computers
O Produced less heat compared to first generation
computers
O They uses punch card for data storage
O Consumed less energy compared to first
generation computers

Third generation
Computers 1965 - 1975
O They used integrated circuit(i.c.) to store
data
O The integrated circuit consisted of many
transistors
O Uses storage disk for data storage e.g.
magnetic disks, tapes
O Third generation computers were more
reliable compared to other previous
generations
O They produced less heat

Fourth Generation Computers
O 1975 to present
O These are computers in use today; they use
sophisticated micro-electronic devices
O These computers uses micro processors to
process data
O The micro processors are single chip which
perform computer operation
O Programs are machine independent
O Were more reliable

Fifth generation computers
1990 to present.
O These are predictions that by
early 21st
century computers will
have developed that will be able
to converse with people, human
communication. With the fifth
generation there will be artificial
intelligent computers.

Categories of Computers
O Computer systems may be classified according to the
data they are designed to process
Analog Computers: Analog Computers
O The analog computers do not directly interact with
numbers, but rather deal with variables measured along
a continuous scale, like the temperature of a room.
O It uses continuous variables for mathematical
operations and utilizes mechanical or electrical energy.
O Analog computers may be accurate to within 0.1% of the
correct value.
O Analog computer can perform several mathematical
operations simultaneously.

Digital Computers
O A digital computer operates on discrete data. That is
Data expressed in 0’s and 1’s
O It works basically by directly counting numbers that
represent numerals, letters or other functional
symbols.
O Digital computers can be further divided into special
purpose and general purpose digital computers.
O A special purpose digital computer is one which has
been designed to perform one specific task. The set
of instructions required for that task is permanently
stored in the computer's memory.
O What this type of computer lacks in variety, it makes
up in speed and efficiency.

Digital computers cont.
O A general purpose computer is one
which can store different programs and
is also re-programmable.
O The only limitation to the versatility of
this type of computer is the extent of
imagination of the human mind.
O In fact, these computers can be made to
perform a surplus of different and varied
functions.

Hybrid Computers
O A hybrid computing system is one in which
desirable characteristics of both the analog
and digital computers are integrated.
O In an intensive care unit, analog computers
may measure the patient's heart rate,
temperature, etc.
O The measurements may then be converted
into numbers and supplied to the digital part
of the system which will thereafter regulate
the flow of certain medications.

Classification According to Size and
Memory Capacity
O The size of a computer often determines its function
and processing capacity.
O The size of computers varies widely from tiny to huge
and is usually dictated by computing requirements.
O The largest computers are supercomputers.
O They are the most powerful, the most expensive, and
the fastest, capable of processing trillions of
instructions per second.
O Users of these computers are governmental agencies,
such as the, National Weather Service, and the
National Defense Agency.
O Also, they are used in the making of movies, space
exploration, and the design of many other machines.06/27/13Fundamentals of Computing by Joel Amenya 15

Mainframe Computers.
O The second largest computers are called
mainframes.
O Mainframe computers process data at very high rates
of speed, measured in the millions of instructions per
second.
O They are very expensive, costing millions of dollars in
some cases.
O Mainframes are designed for multiple users and
process vast amounts of data quickly.
O Banks, insurance companies, manufacturers, mail-
order companies, and airlines are typical users.
O Mainframes are often ‘servers’-- computers that
control the networks of computers.

Microcomputers
O Microcomputers A computer with a
microprocessor and its central processing unit is
known as a microcomputer.
O They do not occupy space as much as
mainframes.
O When supplemented with a keyboard and a
mouse, microcomputers are known as personal
computers.
O A monitor, a keyboard and other similar input
output devices, computer memory in the form of
RAM and a power supply unit come packaged in
a microcomputer.
O These computers can fit on desks or tables and
serve as the best choices for single-user tasks.

Minicomputers
O A minicomputer system is a small general
purpose computer varying in size from a
desktop model to a unit the size of a four
drawer filing cabinet".
O It is quite obvious that there is tremendous
amount of similarity between the more
powerful micros and the lower end minis.
O The same situation exists on the other end
where the lower priced mainframes are
almost similar to the higher priced minis.

Notebook Computers
O Another classification of computer is the
notebook computer.
O It can fit into a briefcase and weigh fewer than
two pounds, yet it can compete with the
microcomputer.
O A larger, heavier version is called a laptop
computer.
O Notebooks generally cost more than
microcomputers but can run most of the
microcomputer software and are more versatile.
O Like other computers, notebook computers are
getting faster, lighter, and more functional.

PDAs
O The smallest computer is the handheld
computer called a personal digital
assistant or a PDA.
O PDAs are used to track appointments and
shipments as well as names and addresses.
O They are called pen-based computers
because they utilize a pen-like stylus that
accepts hand-written input directly on a
touch-sensitive screen.
O You have probably noticed delivery
employees using these.

Factors to consider when buy
a computer
O Cost
O Processing speed
O Storage capacity
O Memory size
O Software and hardware compatibility
O Maintenance support from the
manufacturer
O User needs

Characteristics of a computer
O Speed: Computers work at very high speed
and are much faster than humans. A second
is very large time period time for computer.
A computer can perform billions of
calculations in a second. The time used by a
computer to perform an operation is called
the processing speed. Computer speed is
measured in Mega Hertz (MHz).

Characteristics of a computer
Cont’dO Accuracy Computer provides a high degree of accuracy.
For example, the computer can accurately give the result
of division of any two numbers up to 10 decimal places.
O Diligence. When used for a longer period of time, the
computer does not get tired or fatigued. It can perform
long and complex calculations with the same speed and
accuracy from the start till the end.
O Versatility Computer is versatile in nature. It can perform
different types of tasks with the same ease. 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.

Characteristics of a
computer Cont’dO Storage Capability. Large volumes of data and information
can be stored in the computer and also retrieved
whenever required. Secondary storage devices like floppy
disk and compact disk can store a large amount of data
permanently.
O Reliable. Most errors are caused by humans, not
computers. Computers are capable of storing enormous
amounts of data that must be located and retrieved very
quickly. The capability to store and retrieve volumes of
data is at the core of the Information Age.

Assignment
O Find advantage and disadvantages of using
computers.

Chapter Two
O Computer Components
O Hardware,
O Software,
O Live ware or orgware.

General computer concepts
O What is the meaning of the terms hardware,
software, Information Technology (IT)?
O Hardware • The term hardware refers to
the physical components of a computer
such as the system unit, mouse, keyboard,
monitor etc.

Software
O Software • The software is the
collection of instructions which makes
the computer work.
O For instance, when you type in words via
the keyboard, the software is
responsible for displaying the correct
letters, in the correct place on the creen.
O Software is held either on your
computer’s hard disk, CD-ROM, DVD or
on a diskette (floppy disk) and is loaded
(i.e. copied) from the disk into the
computers RAM (Random Access
Memory), as and when required.

Computer Diag’

Information Technology (IT)
• This is a general term which relates to the use
of computers as an aid to creating and
maintaining data, i.e. information.
O IT is related to all aspects of managing and
processing information, especially within a large
organisation.
O Computers are critical to managing information,
and computer departments within large
organisations are often called IT departments. or
IS departments (Information Services) or MIS
departments (Management Information
Services).

Main parts of a computer
Hardware - Central Processing Unit (CPU)
O In terms of computing power, the CPU is the most
important element of a computer system.
O “It is the brain of the computer.”
O CPU or processor or Microprocessor is an
electronic circuit that can execute a sequence of
stored instructions called programs.
O CPU controls all internal and external devices,
performs arithmetic and logic operations.

Hardware Classification
O Hardware can also be referred to as Devices. These are
the physical parts of a computer that a user can see and
touch. They include
O Input Devices.
O Output Devices.
O Storage Devices.
O Processing Devices.
O Network Devices.

Input
O Input is any data or instructions entered into
the computer’s memory

Input Devices: Giving Commands
O Input devices are types of hardware that
enable you to get programs, data, commands,
and responses into the computer’s memory
Keyboard
Mouse
Stylus

Keyboard
O The keyboard allows the computer user to
enter words, numbers, punctuation, symbols,
and special function commands into the
computer’s memory

Types of Keyboard
O Multimedia keyboard -for playing games
O Enhanced or Extended keyboard – Typically 101
keys laid out in the QWERTY fashion; connected
to the computer by a serial cable
O Cordless keyboard – Uses infrared or radio wave
signals
O Ergonomic keyboard – Designed to help prevent
Cumulative Trauma Disorder (CTD) or damage to
nerve tissues in the wrist and hand due to
repeated motion
Enhanced / Extended
Keyboard
Ergonomic
Keyboard

Types Of keyboard keys
O Function keys as shortcuts for
performing certain functions such as saving
files or printing data. Function keys usually
are lined along the top of the keyboard
labeled F1 through F12, although some
keyboards have fewer and others may have
more.

Types Of keyboard keys cont’d
O Modifiers/ Special pc keys. are special keys
that modify the normal action of another key,
when the two are pressed in combination. For
example, <Alt> + <F4> in Microsoft Windows will
close the program in an active window.
O The most widely-used modifier keys
include the Control key, Shift key and the
Alt key. The Alt key is used to access
additional symbols for keys that have
three symbols printed on them.

O System commands. This are keys used to
issue some system commands to the
computer. They are keys like Break
key/Pause, he SysRq / Print screen key the
Escape key.
O The Print screen command used to capture the
entire screen and send it to the printer, but in
the present it usually puts a screenshot in the
clipboard.
O The Escape key (often abbreviated Esc) is used
to initiate an escape sequence. Its used most
often to mean Stop.

O Numeric keys: The number keys are used
to type numbers. 0,1,2,3,4,5,6,7,8,9. These
are called as number keys
O Alphanumeric keys- used to enter both
numeric and alphabetical data to the
computer.

O Navigation and typing modes
O Navigation keys include a variety of keys which
move the cursor to different positions on the
screen. Arrow keys are programmed to move the
cursor in a specified direction; page scroll keys,
such as the 'Page Up and Page Down keys',
scroll the page up and down. The Home key is
used to return the cursor to the beginning of the
line where the cursor is located; the End key
puts the cursor at the end of the line. The
Tab key advances the cursor to the next tab
stop.

O Miscellaneous
O Not all, computer keyboards have a numeric keypad to
the right of the alphabetic keyboard which contains
numbers, basic mathematical symbols (e.g., addition,
subtraction, etc.), and a few function keys. On
Japanese/Korean keyboards, there may be Language
input keys. Some keyboards have power management
keys (e.g., Power key, Sleep key and Wake key); Internet
keys to access a web browser or E-mail; and/or
multimedia keys, such as volume controls or keys that
can be programmed by the user to launch a specified
software or command like launching a game or minimize
all windows.

Mouse
O The mouse is the most widely used pointing
device
O A mouse is palm sized
O As the mouse is moved, its movements are
mirrored by the on-screen pointer
O Mouse pad – clean, flat surface for mouse
movement

Types of Mouse
O Wheel mouse – Contains a rotating wheel used
to scroll vertically within a text document;
connects to PS/2 port or USB port
O Cordless mouse – Uses infrared signals to
connect to the computer’s IrDA port; it must be
within sight of the receiving port
Wheel
Mouse
Cordless
Mouse

PS/2 Port
The color-coded PS/2 connection ports:
 Purple for keyboard
 Green for mouse

How a Mouse Works Mouse operaton
O Mouse buttons enable the user to initiate
actions
O Clicking (left-, right-, or double-clicking)
allows the user to select an item on the
screen or open a program or dialog box
O Click and drag – Holding down the left
mouse button and moving the mouse
enables the user to move objects on the
screen
O Scrolling- Operation achieved by the use of
the mouse elevator.

Other Types of Pointing Devices
Joystick
Touch Pad
Touch
ScreenTrackball
Pointing
Stick
Pen

Image Processing Systems: Scanners
O Image processing systems are used in
business, industry, and science to input data
without manually keying it in
Scanners

MICR
Image Processing Systems: Scanners
Magnetic-ink character recognition (MICR) A computer can read
numbers and letters printed with ink containing magnetic material.
MICR is used by banks to process cheques. The account details at the
bottom of the cheque can be accurately read in this manner since
MICR is not affected by dirt.
 Optical Mark Reader (OMR) – A scanning device that
senses the magnetized marks from #2 pencils.

Alternative Input Devices
Barcode reader
Microphone – Speech
recognition

Digital Camera
Digital Video
Video-conferencing
Web Cam
Alternative Input Devices

Speech Recognition - Microphone
O Speech recognition is a type of input in which the
computer recognizes words spoken into a microphone
O Special software and a microphone are required
O A microphone – an input device that converts sound
input into electrical signals
O Latest technology uses continuous speech recognition
where the user does not have to pause between words

Digital Cameras
O The image’s light falls on a charge-coupled
device (CCD) which transforms the light’s
patterns into pixels
O Images are stored in the camera using flash
memory. The most popular types are
CompactFlash and SmartMedia.
O Photo-editing programs enable the user to edit
the images
O Good pictures can be taken using point-and-
shoot cameras
O Single-lens reflex (SLR) digital cameras are
expensive and used by professional
photographers

Digital Video
O A video capture board transforms analog
video into digital video
O Codes or compression/decompression
standards are used to compress digital
video files
O A frame rate of 24 frames per second
(fps) is needed to produce a continuous
smooth action

Video-conferencing
O Videoconferencing uses digital video
technology to simulate face-to-face meetings
O Whiteboards, which are a part of the screen,
can be used to write or draw

Web Cam
O A Web cam provides low-
resolution video-
conferencing for Internet
users
O The images are small and
jerky

Output Devices
O Output devices are peripheral devices that
enable users to view or hear the computer’s
processed data
O Visual output – Text, graphics, and video
O Audio output – Sounds, music, and
synthesized speech

Visual Display System
O A visual display system is composed of two parts:
O Video adapter – Responsible for video quality
O Monitor – Displays the video adapter’s output
58

Video Adapter
O A video adapter is also called display adapter, video card,
or graphics card
O It plugs into an expansion slot on the motherboard
O It contains memory called video RAM (VRAM)
O It is designed to work with digital or analog monitors
O It converts digital signals to analog
O It determines a monitor’s maximum resolution
(VGA/Super VGA)
O It determines a monitor’s refresh rate
O 3D graphics adapter – Enables 3-dimensional images
O Multi-display video adapter – Permits a connection of two
monitors at a time

Monitors
O A monitor is a peripheral device which
displays computer output on a screen.
O Screen output is referred to as soft copy.
O Types of monitors:
O Cathode-ray tube (CRT)
O Liquid Crystal Display (LCD or flat-panel)
CRT LCD

Cathode-ray tube (CRT)
O Resembles televisions
O Uses picture tube technology
O Less expensive than a LCD monitor
O Takes up more desk space and uses more
energy than LCD monitors

Liquid Crystal Display (LCD)
O Cells sandwiched between two
transparent layers form images
O Used for notebook computers,
PDAs, cellular phones, and
personal computers
O More expensive than a CRT
monitor
O Takes up less desk space and
uses less energy than CRT
monitors
O Types of LCD monitors:
O Passive-matrix LCD
O Active-matrix LCD
O Gas plasma display
O Field emission display

Monitor Specifications
O Screen size – The diagonal measurement of the
screen surface in inches (15, 17, 19, 21)
O Resolution – The sharpness of the image
determined by the number of horizontal and
vertical dots (pixels) that the screen can
display (800 x 600, 1024 x 768, 1600 x 1200)
O Refresh rate – The speed at which the screen
is redrawn (refreshed) and measured in Hertz
(Hz) (60Hz, 75Hz)

Printers
O A printer is a peripheral device that produces a
physical copy or hard copy of the computer’s
output
O Two basic types:
O Impact printer
O Non-impact printer

Impact Printer
O An impact printer is a printer that has a
print head that contacts the paper to
produce a character
O It uses ink ribbon
O It is noisy, produces Near-letter quality
printouts, and is not commonly used
today
O Dot-matrix – Pins are used to make
characters
Impact printer Dot-matrix

Multifunction Printer
O A multifunction printer combines the functions of
a non-impact printer, scanner, fax machine, and
copier in one unit

Non-impact Printer
O Inkjet printer, also called
a bubble-jet, makes
characters by inserting
dots of ink onto paper
O Letter-quality printouts
O Cost of printer is
inexpensive but ink is
costly
Inkjet Laser
 The non-impact printer is the most commonly used printer
today
 It works quietly compared to an impact printer
 Laser printer works like a
copier
 Quality determined by dots
per inch (dpi) produced
 Color printers available
 High initial costs but
cheaper to operate per page

Plotter
O A plotter is a printer that uses a pen that
moves over a large revolving sheet of
paper
O It produces high-quality images
O It is used in engineering, drafting, map
making, and seism otology

Factors to consider before
buying a printer
O Cost
O Volume expected to be printed
O Nature of reports to be printed
O Range of capability of the selected printer
O The interface with which its to connect to
the computer. E.g. parallel or USB.

Audio Output
O Audio output is the ability of the computer
to output sound
O Two components are needed:
O Sound card – Plays contents of
digitized recordings
O Speakers – Attached to sound card
O Digital formats include WAV, MPEG, MP3,
and MIDI

Processing Devices
CPU
O The program is represented by a series of
numbers that are kept in some kind of
computer memory.
O The CPU processes which is obtained, via the
system bus, from the main memory.
O Results from the CPU are then sent back to
main memory via the system bus.
O In addition to computation the CPU controls
and co-ordinates the operation of the other
major components.
O The CPU has two main components, namely:

Processing Devices

CPU
O The Control Unit -- controls the
fetching of instructions from the main
memory and the subsequent execution of
these instructions.
O Among other tasks carried out are the
control of input and output devices and
the passing of data to the
Arithmetic/Logical Unit for computation.

CPU Component
O The Arithmetic/Logical Unit (ALU) -- carries
out arithmetic operations on integer (whole
number) and real (with a decimal point)
operands.
O It can also perform simple logical tests for
equality and greater than and less than between
operands.
O It is worth noting here that the only operations that
the CPU can carry out are simple arithmetic
operations, comparisons between the result of a
calculation and other values, and the selection of the
next instruction for processing

Components of a CPU
O Registers are
temporary storage
area inside a CPU
O It is a high-speed
memory which holds
only data for
immediate
processing and
results of this
processing

CPU manufacturersO There are basically two best known makers
of CPUs for consumer computers that is
AMD and Intel.
O AMD's current line of processors includes
Athlon, Phenom, Sempron and Turion
processors
O Intel's current line of processors includes:
the Celeron, Pentium, Core 2, Centrino and
Centrino 2 processors.

CPU manufacturers
O Today, Intel is the best-known manufacturer
of computer CPUs.
O Most CPUs conform to the von Neumann
architecture, which says that the CPU must
fetch, decode, execute, and write back the
data in a fairly rapid succession.

MEMORY and STORAGE
What is Storage Device?
O A storage device is a hardware device
designed to store information.
O There are two types of storage devices used
in computers; a 'primary storage' device
and a 'secondary storage' device.
O Primary Storage is Main Memory
O This keeps track of what is currently being
processed. It's volatile memory i.e.
power off erases all data.
O For Main Memory, computers use Random
Access Memory (RAM ). This uses
memory chips and is the fastest but most
expensive type of storage.

MEMORY STORAGE
O Secondary Storage is called Auxiliary Storage
O This is what is not currently being processed.
This is the stuff "filed away", but ready to be
pulled out when needed.
It is nonvolatile. (power off does not
erase)
Auxiliary Storage is used for:
O Input- data & programs.
O Output- saving results of processing

MEMORY STORAGE
MAGNETIC DISKS
O Of the various types of Auxiliary Storage,
the types used most often involve some
type of magnetic disk.
O These come in various sizes and
materials.
O This method uses magnetism to store
the data on a magnetic surface.
O Advantages:- high storage capacity
-reliable
-gives direct access to data

TYPES OF MAGNETIC DISKS
O Diskette / Floppy Disk
O Sizes: Two types 5¼", and 3½"
Several other kinds of removable magnetic
media are in use, such as the popular Zip
disk.
O All of these have a much higher capacity
than floppy disks.
O Some kinds of new computers come without
a floppy disk drive at all.
O Each type of media requires its own drive.
The drives and disks are much more
expensive than floppy drives and disks, but
then, you are getting much larger capacities.

TYPES OF MAGNETIC DISKS
Hard Disks
O These consist of 1 or more metal
platters which are sealed inside a case.
O The metal is one which is magnetic.
O It is usually installed inside the
computer's case, though there are
removable and cartridge types, also.
O Technically the hard drive is what
controls the motion of the hard disks
which contain the data.
O But most people use "hard disk" and
"hard drive" interchangeably.

TYPES OF MAGNETIC
DISKSOPTICAL DISKS
O An entirely different method of recording data is used for optical
disks it uses light.
O To make an optical disk, tiny lasers create peaks and valleys in a
plastic layer on a circular disk.
O In the device that reads the optical disk these peaks and valleys
are read as 1's and 0's by shining another laser on the disk.
CD ROM
O The most common size of optical disk, which stands for Compact
Disk - Read Only Memory.
O It looks just like an audio CD. Almost all software is being
distributed on CDs now. The price of the drives that read the disks
(but can't write one) has dropped low enough that a new system
will come with a CD drive. Such drives will also play your audio CDs,
if you have a sound card and speakers.
O The CDs that contain commercial software are of the Write Once
Read Many (WORM) variety.
O For changing data we need rewritable disks labeled as CD/RW

OPTICAL DISKS
Advantages of Optical Disc
1. The optical disk is much sturdier than the other media
discussed so far. It is physically harder to break or melt or
warp.
2. It is not sensitive to being touched, though it can get
too dirty or scratched to be read.
3. It is entirely unaffected by magnetic fields.
4. Plus you can imprint a pretty label right on the disk!
So for software providers, the optical disk is a great way to
store the software and data that they want to distribute or
sell.
Disadvantages
1. The main disadvantage has been cost.
But the cost of a CD-RW drive has dropped drastically and
quickly.
So for commercial use, the read/write drives are quite
cost effective.
2. It is not easy to copy an optical disk. (This is an
advantage as far as commercial software providers are
concerned!). 06/27/13Fundamentals of Computing by Joel Amenya 84

CHAPTER THREE
SOFTWARE COMPONENTS
O A Computer System is made up of Hardware,
Operating System (OS) and user interface.
O Computer Software can be divided into:
O System programs which manage the operation of
the computer itself
O Application programs, which solve problems for
the users.
O The Operating System controls the entire
Computers’ resources and provides the base
upon which the application programs can be
written 06/27/13Fundamentals of Computing by Joel Amenya 85

Categories of Computer
Software

Definition of Operating
SystemO An OS is the core software component of your
computer program that makes the computing
power available to users by controlling the
hardware using “Drivers”.
O OR- OS is a program that controls the
execution of application programs. It
masks/covers the details of the hardware to
application programs.
O Assignment: What Are The Functions Of
Operating System?

What does a driver do?
O A driver is a specially written program which
understands the operation of the device it interfaces to,
such as a printer, video card, sound card or CD ROM
drive.
O A driver is a program designed to comprehend the
functions of a particular device installed on the
system.
O It translates commands from the operating system or
user into commands understood by the component
computer part it interfaces with.
O It also translates responses from the component
computer part back to responses that can be
understood by the operating system, application
program, or user.

Characteristics of the
operating system
O Reliable
O Protected
O Efficient
O Predictable
O Convenience

Basic Functions of OSO Memory Allocation and loading of programs. O.S must be
responsible for managing all system memory which is currently in use
by programs. This ensures that a program does not interfere with
memory already in use by another program. Since programs time
share, each program must have independent access to memory.
O Job scheduling. The job management function of an OS prepares,
schedules, controls, and monitors jobs submitted for execution to
ensure the most efficient processing. A job is a collection of one or
more related programs and their data
O Peripheral control. The resource management function of an OS
allocates computer resources such as CPU time, main memory,
secondary storage, and input and output devices for use.
O Error reporting. During execution if an error occurs the OS
furnishes the user and tries to minimize effects of the error
O Interfacing the user. The OS establishes a standard means of
communication between users and their computer systems. It does
this by providing a user interface and a standard set of commands
that control the hardware.
O Logging and account. Keeps record of various operation in the
computer

Common Operating Systems
O Originally the operating system was created by each
company that manufactured a processor and
motherboard.
O Operating system was unique to each manufacturer.
O Problem: changing to a new computer meant your
software had to be replaced!
O There was pressure early on to standardize things so
that software could be transferred to the new (and of
course better!) computer. This required more
standardization in operating systems.
O The winner in the PC market was MS-DOS,
Microsoft's Disk Operating System, and its twin
at IBM, PC-DOS, also written by Microsoft

Types of Operating
Systems
O There are several types of operating systems.
O Here is an overview on each system:
O Windows: Windows is the popular Microsoft brand
preferred by most personal users. This system has
come a long way from version 1.0 all the way up to
the new Vista and soon to be released Windows 7.
O Although Windows has made strides in regard to
security, it has a reputation for being one of the
most vulnerable systems.

Microsoft suite of operating
systems
O They include from most recent to the oldest:
O Windows XP Professional Edition - A version used by
many businesses on workstations. It has the ability to
become a member of a corporate domain.
O Windows XP Home Edition - A lower cost version of
Windows XP which is for home use only and should
not be used at a business.
O Windows 2000 - A better version of the Windows NT
operating system which works well both at home and
as a workstation at a business. It includes
technologies which allow hardware to be automatically
detected and other enhancements over Windows NT.

Microsoft suite of operating
systemsO Windows ME - A upgraded version from windows 98
but it has been historically plagued with programming
errors which may be frustrating for home users.
O Windows 98 - This was produced in two main versions.
The first Windows 98 version was plagued with
programming errors but the Windows 98 Second
Edition which came out later was much better with
many errors resolved.
O Windows NT - A version of Windows made specifically
for businesses offering better control over workstation
capabilities to help network administrators.
O Windows 95 - The first version of Windows after the
older Windows 3.x versions offering a better interface
and better library functions for programs.

Types of Operating Systems
O Unix: is an operating system developed by Bell Labs to
handle complex scientific applications.
O University networks are likely to use UNIX, as are
Internet Service Providers.
O It is often used more as a server than a workstation
O Unix OS is well known for its stability.
O Unix is text based, but X-Windows is a net work based
graphical interface for UNIX that some think is even
easier to work with than Windows 98.
O UNIX is a machine-independent operating system, which
means it is not specific to just one type of computer
hardware.

Types of Operating Systems
O Linux is an operating system similar to UNIX that is
becoming more and more popular.
O It is an open-source program created by Linus Torvalds at
the University of Finland, starting in 1991.
O Open source means that the underlying computer code
is freely available to everyone.
O Programmers can work directly with the code and add
features.
O They can sell their customized version of Linux, as long
as the source code is still open to others.

Types of Operating
Systems
O Apple Macintosh: is a multitasking operating system
that was the first graphical interface to achieve
commercial success.
O Recent versions of the Macintosh operating system,
including the Mac OS X, follow the secure architecture
of Unix.
O Apple made a major marketing error when they decided
to keep their hardware and software under tight control
rather than licensing others to produce compatible
devices and programs.
O Systems developed by Apple are efficient and easy to
use, but can only function on Apple branded hardware.

Operating system updates
O Operating systems are updated frequently.
O For example, if users find a bug or security hole
in an operating system, the company that makes
the operating system normally releases an
update called a patch or service pack.
O This allows you to update your operating system
without installing from scratch.
O Check the Web site of the company that writes
your operating system for the latest information
about latest software patches .

Operating system types
O GUI - Short for Graphical User Interface, a GUI Operating System
contains graphics and icons and is commonly navigated by using a
computer mouse.
O Multi-user - A multi-user Operating System allows for multiple
users to use the same computer at the same time and/or different
times. Below are some examples of multi-user Operating Systems.
Linux, Unix, Windows 2000
O Multiprocessing - An Operating System capable of supporting
and utilizing more than one computer processor. Below are some
examples of multiprocessing Operating Systems. Linux, Unix,
Windows 2000
O Multitasking - An Operating system that is capable of allowing
multiple software processes to run at the same time. Below are
some examples of multitasking Operating Systems. Unix, Windows
2000
O Multithreading - Operating systems that allow different parts of
software program to run concurrently. Operating systems that
would fall into this category are: Linux, Windows 2000

UTILITY AND APPLICATION PROGRAMS
O Utility software (also known as service program,
service routine, tool, or utility routine) is computer
software designed to help manage and tune the computer
hardware, operating system or application software by
performing a single task or a small range of tasks.
O Utility Programs perform tasks related to the
maintaining of your computer's health - hardware or data.
O Some utility software has been integrated into most major
operating systems.
O Examples, Disk, Defragmenter, Registry cleaners,
Antivirus, File Management, Data Recovery, Data Back
up, Data Compression, and Memory management.

Application Software
/Programs
O Applications software allows you to
perform a particular task or solve a specific
problem.
Examples of application Software.
O Word Processor Provides the tools for
entering and revising text, adding graphical
elements, formatting and printing documents.
O Spreadsheets Provides the tools for working
with numbers and allows you to create and edit
electronic spreadsheets in managing and
analyzing information.

Examples of application
Software
O Database Management Provides the tools for
management of a collection of interrelated facts.
O Data can be stored, updated, manipulated,
retrieved, and reported in a variety of ways.
O Presentation Graphics Provides the tools for
creating graphics that represent data in a visual,
easily understood format.
O Communication Software Provides the tools for
connecting one computer with another to enable
sending and receiving information and sharing files
and resources. Internet Browser Provides access
to the Internet through a service provider by using a
graphical interface.

Relationship Between
SoftwareO As important as applications software may be, it is not able to
directly communicate with hardware devices.
O Another type of software required is the operating systems
software. OS software is the set of programs that lies
between applications software and the hardware devices.
O Think of the cross section of an onion. The inner core of the
onion represents the hardware devices, and the applications
software represents the outside layer. The middle layer is the
OS software. The instructions must be passed from the outer
layer through the middle layer before reaching the inner layer.
O All computers, regardless of size, require the OS. As soon as
your personal computer is turned on, the OS software is
loaded into RAM in order to use your computer devices and
other software.

What is a computer
virus?
O A computer virus is a small software program that
spreads from one computer to another computer and
that interferes with computer operation. A computer
virus may corrupt or delete data on a computer, use
an e-mail program to spread the virus to other
computers, or even delete everything on the hard
disk.

Symptoms of a computer
virusO The computer runs slower than usual.
O The computer stops responding, or it locks up
frequently.
O The computer crashes, and then it restarts every few
minutes.
O The computer restarts on its own. Additionally, the
computer does not run as usual.
O Applications on the computer do not work correctly.
O Disks or disk drives are inaccessible.
O You cannot print items correctly.
O You see unusual error messages.

virusO You see distorted menus and dialog boxes.
O There is a double extension on an attachment
that you recently opened, such as a .jpg, .vbs, .gif,
or .exe. extension.
O An antivirus program is disabled for no reason.
Additionally, the antivirus program cannot be
restarted.
O An antivirus program cannot be installed on the
computer, or the antivirus program will not run.

virus
O New icons appear on the desktop that you
did not put there, or the icons are not
associated with any recently installed
programs.
O Strange sounds or music plays from the
speakers unexpectedly.
O A program disappears from the computer
even though you did not intentionally
remove the program.

How to eliminate and
cub computer virus.
O Install an anti-virus examples of antiviruses
include:- avast, kaspasky, mcafee, f secure
O Keep Microsoft Updates current
O Only download from reputable sources.
O When downloading free software beware and
read the fine print.
O Install a firewall
O Verify e-mails with attachments from sender. for
even higher security block all attachments.

How to eliminate and
cub computer virus.O Do not open attachments with double extensions
or extensions with the following .vbs .msi, .pif, .scr
O Turn off preview pane in E-mail
O Download music and programs from legitimate
sources not through warez sites or peer-to-peer
file swapping.
O Beware of porn sites especially phone dialers.
O Get of that joke e-mail list
O Have proper back up procedures in place.
O Enable Macro prevention in Microsoft Office

INFORMATION NETWORKS
O A computer network is a group of interconnected
computers.
Advantages of Networks:
O Speed. Sharing and transferring files within Networks
are very rapid. Thus saving time, while maintaining the
integrity of the file.
O Cost. Individually licensed copies of many popular
software programs can be costly. Networkable versions
are available at considerable savings. Shared programs,
on a network allows for easier upgrading of the program
on one single file server, instead of upgrading individual
workstations.

Advantages of
Networks:O Security. Sensitive files and programs on a network
are passwords protected (established for specific
directories to restrict access to authorized users) or
designated as "copy inhibit," so that you do not have
to worry about illegal copying of programs.
O Centralized Software Management. Software
can be loaded on one computer (the file server)
eliminating that need to spend time and energy.
O Resource Sharing. Resources such as, printers,
fax machines and modems can be shared.

USES OF NETWORKS AND
INTERNET
O Sharing music and video files
O Research and on-line learning
O Chatting with friends
O Planning vacations
O Purchasing gifts and supplies

Characteristics of a Computer
NetworkO The primary purpose of a computer network is to share
resources:
O You can play a CD music from one computer while
sitting on another computer
O You may have a computer with a CD writer or a backup
system but the other computer doesn’t have it; In this
case, you can burn CDs or make backups on a
computer that has one of these but using data from a
computer that doesn’t have a CD writer or a backup
system
O You may have a computer that doesn’t have a DVD
player. In this case, you can place a movie DVD on the
computer that has a DVD player, and then view the
movie on a computer that lacks a DVD player

Characteristics of a Computer
Network Cont.
O You can connect a printer (or a scanner, or a fax
machine) to one computer and let other
computers of the network print (or scan, or fax)
to that printer (or scanner, or fax machine)
O You can place a CD with pictures on one
computer and let other computers access those
pictures
O You can create files and store them in one
computer, then access those files from the other
computer (s) connected to it

Disadvantages of
Networks
O One server breaking down may affect a number of
computers
O vulnerable to hackers, Crackers and viruses
O Cabling and installation may be expensive
O a network manager may need to be employed to run the
network
O Could degrade in performance

Types of networks
O 1.PAN-A personal area network (PAN) is a
computer network used for communication
among computer and different information
technological devices close to one person.
O Some examples of devices that are used in a
PAN are personal computers, printers, fax
machines, telephones, PDAs, scanners, and
even video game consoles. A PAN may include
wired and wireless devices. The reach of a PAN
typically extends to 10 meters.

Types of networks Cont’
O 2. A local area network (LAN) supplies
networking capability to a group of
computers in close proximity to each other
such as in an office building, a school, or a
home.
O A LAN is useful for sharing resources like
files, printers, games or other applications.
O A LAN in turn often connects to other LANs,
and to the Internet or other WAN.

Types of networks Cont’d
O A campus network, campus area network,
corporate area network or CAN is a computer
network made up of an interconnection of local
area networks (LANs) within a limited
geographical area. The networking equipments
(switches, routers) and transmission media
(optical fiber, copper plant, Cat5 cabling etc)
are almost entirely owned by the campus
tenant / owner: an enterprise, university,
government etc

2.Wide-Area Network
O The term Wide Area Network (WAN) usually refers to a
network which covers a large geographical area.
O A computer network that spans a relatively large
geographical area.
O Typically, a WAN consists of two or more local-area
networks (LANs).
O Computers connected to a wide-area network are often
connected through public networks, such as the
telephone system.
O They can also be connected through leased lines or
satellites.
O The largest WAN in existence is the Internet.

O Global area networkGlobal (GAN)refers to
any network that is composed of different
interconnected computer networks (WANs) and
also covers an unlimited geographical area.
O Storage Area Network - connects servers to
data storage devices through a technology like
Fibre Channel.
O System Area Network - links high-performance
computers with high-speed connections in a
cluster configuration. Also known as Cluster Area
Network.

Network topology
O Linear Bus Topology A linear bus
topology consists of a main run of cable with
a terminator at each end (See fig. 1). All
nodes (file server, workstations, and
peripherals) are connected to the linear
cable.

Network topology Cont’d
O Advantages of a Linear Bus Topology
O Easy to connect a computer or peripheral to a linear bus.
O Requires less cable length than a star topology.
O Disadvantages of a Linear Bus Topology
O Entire network shuts down if there is a break in the main
cable.
O Terminators are required at both ends of the backbone
cable.
O Difficult to identify the problem if the entire network
shuts down.
O Not meant to be used as a stand-alone solution in a
large building.

O Ring network topology
O A network topology that is set up in a
circular fashion in which data travels around
the ring in one direction and each device on
the right acts as a repeater to keep the
signal strong as it travels. Each device
incorporates a receiver for the incoming
signal and a transmitter to send the data on
to the next device in the ring. The network is
dependent on the ability of the signal to
travel around the ring.

O Star
O A star topology is designed with each node (file server,
workstations, and peripherals) connected directly to a
central network hub, switch, or concentrator (See fig. 2).
O Data on a star network passes through the hub, switch, or
concentrator before continuing to its destination. The hub,
switch, or concentrator manages and controls all
functions of the network. It also acts as a repeater for the
data flow. This configuration is common with twisted pair
cable; however, it can also be used with coaxial cable or
fiber optic cable.

O Star topology

O Advantages of a Star Topology
O Easy to install and wire.
O No disruptions to the network when connecting or
removing devices.
O Easy to detect faults and to remove parts.
O Disadvantages of a Star Topology
O Requires more cable length than a linear topology.
O If the hub, switch, or concentrator fails, nodes attached
are disabled.
O More expensive than linear bus topologies because of the
cost of the hubs, etc. 06/27/13Fundamentals of Computing by Joel Amenya 127

Network topology Cont’dO Tree or Expanded Star
O A tree topology combines characteristics of linear bus and
star topologies. It consists of groups of star-configured
workstations connected to a linear bus backbone cable
(See fig. 3). Tree topologies allow for the expansion of an
existing network, and enable schools to configure a
network to meet their needs.

Advantages of a Tree Topology
O Point-to-point wiring for individual segments.
O Supported by several hardware and
software venders.
Disadvantages of a Tree Topology
O Overall length of each segment is limited by
the type of cabling used.
O If the backbone line breaks, the entire
segment goes down.
O More difficult to configure and wire than
other topologies.

Network topology Cont’dO Mesh Topology
Mesh topologies involve the concept of routes. Unlike
each of the previous topologies, messages sent on a
mesh network can take any of several possible paths
from source to destination. (Recall that even in a ring,
although two cable paths exist, messages can only
travel in one direction.) Some WANs, most notably the
Internet, employ mesh routing.
O A mesh network in which every device connects to
every other is called a full mesh. As shown in the
illustration below, partial mesh networks also exist in
which some devices connect only indirectly to others.

INTRODUCTION TO
WINDOWS OPERATING
SYSTEM
Starting, Shutting Down And Restarting
Windows
Turning on the PC
O Most PCs will have a single switch in the front that is activated to provide
power.
O The monitor will also have a power switch in most cases. Usually this is
in the front or lower right portion of the display case.
O The startup process of a computer is also referred to as booting the
system. There are two types:
O A cold boot is performed when the PC is turned on using the power
button.
O At the end of this process, the Windows operating system desktop will
be displayed.
O Before starting your computer make sure you do not have a diskette in
your A drive

Shutting Down a
Computer
O To shutdown the computer, click on the Start button on the lower left
corner of the Windows Taskbar, and select Shut Down.
O Alternatively, press Ctrl-Alt-Delete and click Shut Down from the
menu that displays.
O Do not switch the computer off until a message displays indicating
that it is safe to do so.
O Important data that is stored in memory while the system is operating
needs to be written to the hard disk before switching off the
computer.
O Newer computers will automatically shut off power when the
shutdown process is complete.
O NOTE: It is extremely important not to power off the computer with
the power switch. Most operating systems like Macintosh and
Windows have a specific method for turning the system off. In
Windows, choose the Shut Down button from the Start menu. On a
Macintosh, choose the Shut Down button from the Special menu06/27/13Fundamentals of Computing by Joel Amenya 134

Restarting the PC
O Restarting a PC that has already been powered up is referred to as
a warm boot.
O This can be achieved by pressing the reset button on the front
panel.
O Alternatively, press Ctrl- Alt-Delete, and click Restart from the
menu that displays.
O Sometimes your computer will start doing funny things or your
mouse will stop working
O Try ALT + CTL + DELETE
O If you see a program is not responding, you can try to highlight that
program and press the “End Task” button.
O If nothing happens try ALT + CTL + DELETE again. This will restart
your computer

Mouse
O Pointing device that moves pointer or cursor
O Point and click (tip of the arrow is the point)
O Left and right buttons
O Start programs - 1 click vs 2 clicks
O Highlight text (click and drag)
O Practice makes perfect

Cursor Types
O Arrow
O Busy
O Text
O Double arrow
O Hand

The Desktop
O The main display screen in Windows is
known as the desktop.
O IT refers to the main background area.
O You can customize your desktop in various
ways, including adding a background
picture, changing the background colour,
and changing the size of the icons on the
desktop.

The Desktop

Features of a Desktop
O Icons are small graphical images that can represent your computer's
programs, files, folders and printers amongst other things
O To activate the program/file/folder that an icon represents you simply
double click (two clicks in quick succession) on it with the left mouse
button.
O This will activate the icon and either start a program or open a
file/folder.
O It can also be non selectable as in a company logo on a web page.
O Some of the icons on the desktop, such as My Computer, Network
Neighbourhood, My Network Places, Recycle Bin, or My Documents,
are shortcuts to those directories.
O Other icons that may be on the desktop, such as Microsoft Word,
Excel, or Adobe Photoshop, are shortcuts to those applications.
O The My Computer icon gives access to all the installed drives, which
are computer storage components.

Features of a Desktop
O Recycle Bin
When you delete a file, Windows XP will
place the file into the recycle bin (instead of
deleting it altogether), this allows you to
restore the file in case you deleted it by
mistake.

Start button
O Clicking on the start button
opens up what is called the start
menu, the start menu is used to
access your programs, settings,
printers and almost all functions
on PC.
O The quick launch buttons are
located on the taskbar next to
the Start button.
O These buttons allow immediate
access to the desktop from any
application, as well as access to
Internet Explorer and Outlook
Express.

Start Menu OverviewO Log off - Log off the current user.
O Turn Off Computer - shutdown, restart and standby.
O All Programs - Access to installed programs.
O Run - Used to manually start executable files (programs).
O Search - Search your PC for pictures, music, documents, files and
folders.
O
Help and Support - Opens the built-in Windows help system, including
various help and support topics.
O You can control windows updates and also request remote assistance
from a friend/colleague via the internet or network.
O Printers and Faxes - Access to your printers and faxes folder, allows
you to add and configure printers/faxes.
O Control Panel - The control panel is used to configure various
Windows XP settings. We will be looking at the Win XP control panel in
detail later in the tutorial.

Start Menu Overview
O My Computer - Gives you access to your computer's disk
drives and files.
O My Music - Links to a folder created by Windows XP which
is used (by default) to store any music files on your hard
drive.
O My Pictures - Links to a folder (again created by Windows
XP) used (by default) to store any pictures/images on your
hard drive.
O My Recent Documents - This folder contains any recently
viewed documents.
O My Documents - Gives access to a folder created by
Windows XP which is used (by default) to store any
documents on your hard drive. 06/27/13Fundamentals of Computing by Joel Amenya 144

Start Menu Overview
O Tour Windows XP - Starts the built-
in tour of Windows XP's features.
O Windows Movie Maker - Opens
Windows XP's movie editing software.
O Outlook Express - Opens the
Outlook Express mail program.
O Files and Settings Transfer
Wizard - Allows you to import or
export your files and settings from or
to a different installation of Windows
XP. 06/27/13Fundamentals of Computing by Joel Amenya 145

The All Programs Menu
O When you hover the mouse over All Programs on
the start menu, you will see a menu appear.
O The menu gives you access to the programs
currently installed on your PC.
O Your menu will be different from our example, as
you will have different programs installed on your
PC.
O To open a program simply left click on it with the
left mouse button.
O Notice some options have a small black arrow to
the right hand side, this indicates that it contains
another sub-menu.

All program menu cont.
O You can rename any program on the menu
by right clicking on it and selecting rename
from the menu that appears.
O After installing new software it will (usually)
appear on the programs menu.
O To remove a program from the All
Programs menu simply right click on it and
select delete.
O NOTE: if you want to uninstall a program
then use the control panel to uninstall it.
O Simply deleting it from the programs menu
will not uninstall the software.

The Task Bar
O Start Button - The Start Button is used to
access the Windows XP start menu
O Window Tabs - The Windows tabs are used to
switch between any open windows (programs,
folders, documents, etc).
O You can switch between the windows by simply
clicking on the corresponding window tab, clicking
a second time on the same tab will minimize the
window.

Features of a Task bar
O Grouping Window Tabs - When the taskbar fills up with
window tabs it can group all files/windows within a single
program into just one window tab. In other words, if you
have 2 documents open in Word, you will only have one tab
on the taskbar (instead of 2).
O You can then access each document by left clicking on the
tab and selecting the file/window you want from the menu
that appears.
O This feature can be switched off by right clicking on the
taskbar, clicking on properties and then unchecking the
box next to Group similar taskbar buttons.
O System Tray - The system tray displays icons for programs
that are loaded into memory, although not all programs
place an icon in this tray

Features of a Task Bar
O The Quick Launch Bar
By default, Windows XP has the quick launch bar hidden, if you want to
use the quick launch bar you need to activate it.
O To do this simply right click on the taskbar, hover the mouse pointer
over toolbars and then put a tick in the box next to Quick Launch.
The Windows XP quick launch bar provides direct access to your
programs, files or folders with just one click.
O It is bar is visible (by default) even when you have a window open.

Task Bar Cont.
O When you first enable the quick launch bar there are normally a couple
of icons visible:
- Show Desktop Icon - This icon is used to minimise all open
windows to show the windows xp desktop, clicking again will restore the
windows to their previous state.
- Internet Explorer Icon -This icon will open Microsoft's Internet
Explorer browser.
Adding icons to quick launch bar
O Simply drag the icon of the program/file/folder over the quick launch
bar and drop it (release the mouse button).
O If you add or delete icons you can increase or decrease the size of the
quick launch bar by moving the divider
O To delete an icon from it , Right click on the icon you want to delete
and then select delete from the menu that appears.

Explorer
O Windows Explorer is an application that provides
detailed information about your files, folders, and
drives.
O It is also the component of the operating system that
presents the user interface on the monitor and enables
the user to control the computer.
O It is sometimes referred to as the Windows Shell, or
simply “Explorer”.
O You can use it to see how your files are organized and to
copy, move, and rename files, as well as perform other
tasks pertaining to files, folders, and drives.

Opening Explorer
O The simplest way to access Windows Explorer is
to right-click the Start menu or the My
Computer icon and select Explore.
O OR hold down the START button and press the
E key.
O Or click the START button, click run, type
explorer into the box and press enter.
O Or open My Computer and click on the
Folders button at the top of the My
Computer environment.
O In newer operating systems, it is under
Accessories.

Copying, Deleting, and
Renaming Files and FoldersO All of these tasks are straight forward and can be
achieved by right clicking in a folder where you want to
make the action.
You will be presented with the window below;

Working With Icons
O Creating Shortcuts (Icons)
O Go to the program or file in Windows Explorer.
Right-click the program or file and select Create
Shortcut
O OR Right-click on the desktop and select New >
New Shortcut or Create Shortcut.
O Enter the path for the program or file, and the
shortcut will display on the desktop.

Working With IconsO Moving Icons
O To move the created icon or another desktop icon to
another position on the desktop, click on it and then
drag it to the desired location. The icon becomes semi-
transparent while being dragged. To restore the icon to
full intensity, click outside of it. If the icon does not
move, disable the Auto Arrange function on the
desktop.
O To do this, right-click on an empty space of the desktop
and uncheck the Auto Arrange selection. Shortcut
icons can be created for frequently used programs such
as web browsers, word processors, spreadsheets, and
instant messengers.

Working with Icons
O Selecting Multiple Icons
O To simultaneously select and move several icons, hold down the Ctrl
key and click on all the icons that are to be moved. Then drag the group
of icons to the new location and let go of the mouse button. De-select
the icons by clicking on an empty part of the desktop.
O Renaming Icons
O There are two ways to rename an icon;
O The first way is to simply click once on the name under the icon, then
type in a new name. Click on an empty part of the desktop to complete
the action.
O The second ways is to right-click on the icon and select the Rename
option.
O Navigating and working with the desktop is easier with the use of icons.
Since icons are simply shortcuts that point to programs and files, they
can be copied, moved, and even deleted without affecting the program
or file.

Scrolling pages
O Mouse
O Click on up and down arrows
or
O Click on top of and below that darker box
without touching the box
or
O Click and drag the darker box
O Keyboard (make sure cursor is on page
by clicking on empty space)
O Use arrow keys
O Use page up, page down, home and end

Opening Programs
O If on desktop as icon, double click on icon. If
does not open press “Enter” key.
O Click on “Start” button, Move cursor up to
“Programs”. After menu on the right appears
move cursor over to menu and up or down to
required program. Click on program
O If program has been minimized and appears on
task bar, click on square representing program.

SDLC and Related
Methodologies

Contemplative Questions
O What are the various approaches to
developing Information Systems?
O Is there one best way?
O What is the difference between techniques,
methodologies and tools?
O What does the popular term “SDLC” actually
mean?

SDLC
O SDLC stands for
O Systems
O Development
O Life
O Cycle
O What does it mean?

SDLC
O SDLC stands for
O Systems Development Life Cycle
O First, SDLC is a Life Cycle.
O All systems have a life cycle or a series of stages they
naturally undergo.
O The number and name of the stages varies, but the primary
stages are conception, development, maturity and decline.
O The systems development life cycle (SDLC) therefore,
refers to the development stage of the system’s life cycle.
Why are we so interested in the development stage?
What about conception, maturity and decline?

Typical Reasons to Initiate a
Systems Development Project
Desire to make more
effective use of information
Problems with existing systems
Desire to exploit new opportunities
Increasing competition
Organizational growth
Merger or acquisition
Change in market or
external environment
Perception of potential
benefit by individual
capable of initiating
change
Systems development
process initiated

Methodologies
O Is there a difference between the term SDLC and the
term ‘methodology’?
O Whereas the SDLC refers to a stage all systems
naturally undergo, a methodology refers to an
approach invented by humans to manage the events
naturally occurring in the SDLC.
O A methodology is, in simple terms, a set of steps,
guidelines, activities and/or principles to follow in a
particular situation.
O Most methodologies are comprehensive, multi-step
approaches to systems development
O There are many methodologies out there. See
www.methodology.org .

SDLC vs. Methodology
O It is confusing, but unfortunately, the term
SDLC is frequently used synonymously with the
waterfall or traditional approach for
developing information systems.
O “The SDLC approach”
O This approach essentially refers to a linear sequence of
stages to develop a system from planning to analysis to
design to implementation.
O Stages are followed from beginning to end.
O Revisiting prior stages is not permitted.

Databases and Application
Independence
O Database
O Shared collection of logically related data
O Organized to facilitate capture, storage and
retrieval by multiple users
O Centrally managed
O Designed around subjects such as Customers or
Suppliers
O Application Independence
O Separation of data from the applications, e.g.
O Payroll data is part of the enterprise-wide data model
and can be used by many systems, not just the Payroll
System

Systems Development Life
Cycle
O Every textbook has different names for the
stages of the SDLC
O Usually they stages are
O Planning (just after Conception)
O Analysis
O Design
O Implementation
O Maintenance (starting Maturity)
1.
168

Cycle
O This text highlights 6 distinct phases:
O Project Identification and Selection
O Project Initiation and Planning
O Analysis
O Design
O Implementation
O Maintenance

Stages of the SDLC
IS
421
System
s Analysis
IS
422
System
s Design

Phases of the Systems
Development Life Cycle
1. Project Identification and Selection
O Two Main Activities
O Identification of need
O Prioritization and translation of need into a development
schedule
O Helps organization to determine whether or not
resources should be dedicated to a project.
1. Project Initiation and Planning
O Two Activities
O Formal preliminary investigation of the problem at hand
O Presentation of reasons why system should or should
not be developed by the organization

Cycle
O Analysis
O Study of current procedures and information
systems
O Determine requirements
O Study current system
O Structure requirements and eliminate
redundancies
O Generate alternative designs
O Compare alternatives
O Recommend best alternative

Cycle
O Design
O Logical Design
O Concentrates on business aspects of the system
O Physical Design
O Technical specifications
O Implementation
O Implementation
O Hardware and software installation
O Programming
O User Training
O Documentation

Cycle
O Maintenance
O System changed to reflect changing conditions
O System obsolescence
A good way to learn the stages of the SDLC is
to create deliverables (output) of each stage
in the process.

Alternative Approaches
O Prototyping
O Building a scaled-down working version of
the system
O Advantages:
O Users are involved in design
O Captures requirements in concrete form
O Rapid Application Development (RAD)
O Utilizes prototyping to delay producing
system design until after user
requirements are clear

O Joint Application Design (JAD)
O Users, Managers and Analysts work together
for several days
O System requirements are reviewed
O Structured meetings
O We will see a video on this when we cover
Chapter 7

O Evolutionary or spiral methodology
The *** never gets done! Different versions, always in
different stages.

Fundamentals of Computing

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