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Definition of a computer(rvd[1]2

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Simplified approach to computer science
Sir Wagner ™
ii
TABLE OF CONTENTS
Contents
TABLE OF CONTENTS ........................................................................................................................... II
INTRODUCTION TO COMPUTER SCIENCE ........................................................................................... 1
DEFINITION OF A COMPUTER .............................................................................................................. 1
Components of a computer ....................................................................................................................... 1
CLASSIFICATION OF COMPUTERS ....................................................................................................... 1
Super computer ......................................................................................................................................... 1
Characteristics ........................................................................................................................................... 1
Mainframe computers ............................................................................................................................... 1
Characteristics ........................................................................................................................................... 2
Mini computers ......................................................................................................................................... 2
Characteristics ........................................................................................................................................... 2
Desktop computers.................................................................................................................................... 2
Characteristics ........................................................................................................................................... 2
HARD WARE AND SOFTWARE ............................................................................................................. 3
HARDWARE ........................................................................................................................................... 3
Categories of hardware ............................................................................................................................. 3
INPUT DEVICES ..................................................................................................................................... 3
OUTPUT DEVICES ................................................................................................................................. 3
STORAGE DEVICES .............................................................................................................................. 6
APPLICATION OF HARDWARE DEVICES ............................................................................................ 8
Point of sale (POS) terminal ..................................................................................................................... 8
Automated Teller Machine (ATM) ........................................................................................................... 8
Components of an ATM ........................................................................................................................... 9
Data capturing systems ............................................................................................................................. 9
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SOFTWARE ........................................................................................................................................... 10
Classes of software ................................................................................................................................. 10
APPLICATION SOFTWARE ................................................................................................................ 10
General purpose software ....................................................................................................................... 10
Special purpose software ........................................................................................................................ 10
Off the shelf software.............................................................................................................................. 10
Customised software ............................................................................................................................... 11
SYSTEMS SOFTWARE ........................................................................................................................ 11
Operating System .................................................................................................................................... 12
Functions of operating system ................................................................................................................ 12
Types of operating systems ..................................................................................................................... 13
Personal computer operating system....................................................................................................... 13
Utilities.................................................................................................................................................... 14
Language translators ............................................................................................................................... 14
HARDWARE AND SOFTWARE MAINTENANCE ................................................................................. 14
Relationship between hardware and software ......................................................................................... 14
Troubleshooting ...................................................................................................................................... 14
COMPUTER NETWORKS AND INTERNET TECHNOLOGIES .............................................................. 15
COMPUTER NETWORKS ...................................................................................................................... 15
Reasons for networking .......................................................................................................................... 15
Advantages of Networking ..................................................................................................................... 15
Disadvantages of Networking ................................................................................................................. 15
Network architectures ............................................................................................................................. 15
Peer to peer network ............................................................................................................................... 15
Classification of networks....................................................................................................................... 16
Classes of Networks ................................................................................................................................ 16
LANS and WANS................................................................................................................................... 16
Local area network.................................................................................................................................. 16
Pan and can ............................................................................................................................................. 16
Wide area network .................................................................................................................................. 16
Network topologies ................................................................................................................................. 16
Topologies include .................................................................................................................................. 16
Bus topology: .......................................................................................................................................... 16
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Star topology: .......................................................................................................................................... 16
Ring network topology ........................................................................................................................... 16
Advantages of Ring Network.................................................................................................................. 17
Disadvantages of Ring Network ............................................................................................................. 17
Mesh Network......................................................................................................................................... 17
Advantages of Mesh Network................................................................................................................. 17
Disadvantages of Mesh Network ............................................................................................................ 17
INTERNET SERVICES ........................................................................................................................... 17
Email ....................................................................................................................................................... 17
E-commerce ............................................................................................................................................ 17
E-learning................................................................................................................................................ 18
Social media ............................................................................................................................................ 18
DATA TRANSMISSION ......................................................................................................................... 18
Data transmission modes ........................................................................................................................ 18
Full duplex/Duplex ................................................................................................................................. 18
Advantages of Duplex............................................................................................................................. 18
Half Duplex transmission modes ............................................................................................................ 19
Advantages of Half Duplex Transmission .............................................................................................. 19
Simplex transmission .............................................................................................................................. 19
Advantages.............................................................................................................................................. 19
DATA TRANSMISSION MEDIA ............................................................................................................ 19
Bounded media ....................................................................................................................................... 19
Twisted pair cable ................................................................................................................................... 19
Characteristics of twisted pair cables ...................................................................................................... 20
Coaxial cable........................................................................................................................................... 20
Characteristics ......................................................................................................................................... 20
Fibre optic cable...................................................................................................................................... 20
Fibre optic cable characteristics .............................................................................................................. 20
Unbounded transmission media .............................................................................................................. 20
Radio transmission .................................................................................................................................. 20
Characteristics of radio frequency transmission ..................................................................................... 20
Microwave transmission ......................................................................................................................... 21
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Satellite transmission .............................................................................................................................. 21
Internet service providers ........................................................................................................................ 21
Services offered by ISPs ......................................................................................................................... 21
MOBILE TECHNOLOGIES .................................................................................................................... 21
Mobile phone .......................................................................................................................................... 21
Feature phone .......................................................................................................................................... 21
Smartphones............................................................................................................................................ 21
Satellite communication.......................................................................................................................... 21
PDA Personal digital assistant ................................................................................................................ 22
Tablet ...................................................................................................................................................... 22
Application of mobile technologies ........................................................................................................ 22
Agriculture .............................................................................................................................................. 22
Communication ....................................................................................................................................... 22
Entertainment .......................................................................................................................................... 22
Education ................................................................................................................................................ 22
Mobile shopping ..................................................................................................................................... 23
Mobile banking ....................................................................................................................................... 23
Mobile marketing .................................................................................................................................... 23
WIRELESS TECHNOLOGIES ............................................................................................................... 23
WiFi ........................................................................................................................................................ 23
WiMax .................................................................................................................................................... 23
Bluetooth ................................................................................................................................................. 24
Infrared.................................................................................................................................................... 24
Microwave .............................................................................................................................................. 24
COMMUNICATION PROTOCOLS ........................................................................................................ 24
Networking hardware.............................................................................................................................. 24
Network interface card ............................................................................................................................ 24
Modem .................................................................................................................................................... 25
Switch ..................................................................................................................................................... 25
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SECURITY AND ETHICS ..................................................................................................................... 26
COMPUTER VIRUS .............................................................................................................................. 26
How does it affect a computer?............................................................................................................... 26
How do viruses spread? .......................................................................................................................... 26
Methods of preventing viruses ................................................................................................................ 26
Ethics ...................................................................................................................................................... 26
Cyber security ......................................................................................................................................... 26
CYBER WELLNESS .............................................................................................................................. 27
Importance of cyber wellness ................................................................................................................. 27
Cyber use ................................................................................................................................................ 27
Characteristics of safe and unsafe sites ................................................................................................... 27
Signs of a safe website ............................................................................................................................ 27
Signs of an unsafe website ...................................................................................................................... 27
Handling online content and behavior .................................................................................................... 27
Online Relationships ............................................................................................................................... 28
COPYRIGHT ISSUES ............................................................................................................................ 28
Copyright ................................................................................................................................................ 28
Copyright infringement ........................................................................................................................... 28
Importance of copyrights ........................................................................................................................ 28
PLAGIARISM AND PIRACY ................................................................................................................ 28
Plagiarism ............................................................................................................................................... 28
Consequences of plagiarism.................................................................................................................... 28
Piracy ...................................................................................................................................................... 28
Consequences of piracy .......................................................................................................................... 28
COMPUTER CRIME.............................................................................................................................. 29
Data protection measures ........................................................................................................................ 29
COMPUTER ETHICS ............................................................................................................................ 29
The ten commandments of computer ethics ........................................................................................... 29
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PRIVACY .............................................................................................................................................. 29
DATA INTEGRITY ............................................................................................................................... 30
It may be compromised by ...................................................................................................................... 30
Data integrity best practices include: ...................................................................................................... 30
DATA VERIFICATION ......................................................................................................................... 30
Data validation methods ......................................................................................................................... 30
DATA VALIDATION ............................................................................................................................ 30
Data validation methods ......................................................................................................................... 30
SYSTEM SECURITY .............................................................................................................................. 31
Network security measures ..................................................................................................................... 31
Fire wall .................................................................................................................................................. 31
Intrusion detection system IDS ............................................................................................................... 31
Types ....................................................................................................................................................... 31
Proxy server ............................................................................................................................................ 31
Encryption ............................................................................................................................................... 31
Additional safeguards to computer network and data ............................................................................. 32
CYBER CRIME ..................................................................................................................................... 32
Common types of cybercrime ................................................................................................................. 32
Effects of cybercrime .............................................................................................................................. 32
Examples of cyber crime ........................................................................................................................ 32
Spoofing .................................................................................................................................................. 32
Sniffing ................................................................................................................................................... 32
Fraud ....................................................................................................................................................... 32
Hacking ................................................................................................................................................... 32
DATA BACKUP .................................................................................................................................... 33
Reasons for backup ................................................................................................................................. 33
Backup hardware .................................................................................................................................... 33
Magnetic tape .......................................................................................................................................... 33
Magnetic disc .......................................................................................................................................... 33
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TYPES OF BACKUP ............................................................................................................................. 33
Complete backup .................................................................................................................................... 33
Partial backup.......................................................................................................................................... 34
User defined backup ............................................................................................................................... 34
CLOUD BACKUP .................................................................................................................................. 34
DATA LOSS PREVENTION .................................................................................................................. 34
DATA RECOVERY ............................................................................................................................... 34
Data loss can be caused by...................................................................................................................... 34
Data can be recovered from .................................................................................................................... 34
DATA RECOVERY TOOLS ................................................................................................................... 34
Disaster recovery .................................................................................................................................... 34
Disaster recovery plan............................................................................................................................. 35
Factors to consider .................................................................................................................................. 35
Creating a disaster recovery plan ............................................................................................................ 35
Document the DRP ................................................................................................................................. 35
Test the DRP ........................................................................................................................................... 35
SYSTEMS ANALSIS AND DESIGN ...................................................................................................... 36
SYSTEMS DEVELOPMENT LIFE CYCLE ............................................................................................ 36
The generic model................................................................................................................................... 36
STAGES IN THE SYSTEMS DEVELOPMENT LIFE CYCLE Abbreviation: (P.F.A.D.I.C.M.) ....... 36
PROBLEM IDENTIFICATION/ RECOGNITION/DEFINITION and Problem Solving ..................... 37
The problem solving process .................................................................................................................. 37
Data collection techniques ...................................................................................................................... 37
FEASIBILITY STUDY .......................................................................................................................... 38
SYSTEM ANALYSIS ............................................................................................................................ 39
SYSTEMS DESIGN .................................................................................................................................... 42
DEVELOPMENT AND TESTING ................................................................................................................. 44
DOCUMENTATION .................................................................................................................................. 45
SYSTEM IMPLEMENTATION .................................................................................................................... 46
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INTRODUCTION TO COMPUTER SCIENCE
Definition of a computer
A computer is an electronic device that operates by following instructions stored in its memory that accepts data as
input, process it (processing) following specified procedures to produce results as output and store the information
as storage for later use.
Components of a computer
Control unit
Input device
Arithmetic/Logic
Unit
Output device
Memory unit
Classification of Computers
Super computer, mainframe, minicomputer, desktop, and portable computers
Super computer
A computer with great speed and memory, It can do jobs faster than other computers of its generation.
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Characteristics
It is the largest computer
It is the fastest computer
It is the most expensive computer
It can handle over ten thousand (10000) users at a time.
It is mainly used in large scientific and research laboratories for processing speed, memory and other
services which may not be available in smaller computers.
Mainframe computers
They are powerful computers
Mainly used by government institutions and companies
Used for tasks such as census, industry and consumer statistics,
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The term is used to distinguish very big computers from less powerful ones.
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Characteristics
Smaller than supercomputer
Less processing speed than super computer
Cheaper than super computers
Can be used by hundreds of users at the same time
They can be big enough to occupy an entire room
Ideally used as servers in organisations
Mini computers
It is a computer that possesses most of the features and capabilities of a mainframe computer but smaller in size. It
fills the space between a microcomputer and mainframe computer. They are mainly used as small to mid-range
servers operating businesses and scientific applications. However, the term minicomputer has diminished and has
merged with servers.
It may also being called a mid-range computer.
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Characteristics
Smaller than mainframe computer
Mostly used by businesses to process large amounts of information such as controlling ATMs
Used for inventory control in supermarkets, insurance claim processing and payroll
Desktop computers
A personal computer designed for regular use
Personal computer pc is the common name
Used at a single location.
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Characteristics
Cheap and easy to use
Small enough to fit on top of desks and are rarely moved
Widely used for business, academic and home applications
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HARD WARE AND SOFTWARE
HARDWARE
It comprises of several components that fall into two broad categories, namely, hardware and software.
Hardware these are the physical components of a computer those we can see and touch.
 Physical components of a computer system such as input devices processing devices and output or storage
devices.
Categories of hardware
Hardware can be categorised into input devices, output devices, processing devices, and storage devices.
INPUT DEVICES
Keying devices are used to enter data into a computer by typing on keys with letters, numbers, mathematical
symbols and other special symbols.
 The most common is a QWERTY keyboard. Keyboards can also be seen on other devices such as ATMs
 They can be virtual or physical
Pointing devices used by a user to point to a desired location on a computer
 Mouse, trackball, touch pad l and joysticks are all pointing devices
Scanning devices they capture a copy of texts or photographs from a paper and reproduces same data on the
computer
 Image scanners are used to transform printed images into an electronic format that can be stored (saved) in
the computer.
Special purpose scanner
OUTPUT DEVICES
•Any peripheral that receives or displays output from a computer.
•Computer hardware equipment used to communicate the results of data processing carried out by a computer to the
outside world
Computers produce softcopy output, hardcopy output and audio output
A soft copy is the unprinted digital document file
A hardcopy is produced on a paper or some material that can be touched and carried for being shown to others
Audio output is the ability of the computer to output sound
Examples of Output Device
Monitor
Printer
Plotter
Speakers
Projector
Monitor
•The device which displays computer output as softcopy.
•The monitor displays the video and graphics information generated by the computer through the video card.
•Monitors are very similar to televisions but usually display information at a much higher resolution.
Monitors can display graphics, text and video.
The size of a monitor is measured in inches diagonally across the screen;
15, 17, 19 and 21 inch monitors are the most common sizes.
A color monitor can display from 16 to over 1 million different colors.
Types of Monitor
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•Cathode Ray Tube (CRT)
•Liquid Crystal Display (LCD)
•Light-emitting Diode
Cathode Ray Tube (CRT)
•Large
•Heavy
•Produce heat
•Not expensive
Liquid Crystal Display (LCD)
•Less space
•Lighter
•Low power consumption
•Expensive
•Limited viewing angle
Light-emitting Diode (LED)
•Less space
•Lighter
•Very expensive
•Provide higher contrast and better viewing angles than LCD monitor
Printer
•Printer is an external hardware device responsible for taking computer data and generating a hard copy of that
data.
•Printers are one of the most used peripherals on computers and are commonly used to print text, images, and
photos
Types of Printer
Printers can be categorised into:
•Impact Printer
•Non-Impact Printer
Impact Printer
•It strikes paper and ribbon together to form a character, like a typewriter.
Advantages
Disadvantages
•Less expensive
•Can make multiple copies with multipart paper
•Noisy
•Print quality lower in some types
•Poor graphics or none at all
•Slow
Daisy-wheel
•Similar to a ball-head typewriter, this type of printer has a plastic or metal wheel on which the shape of each
character stands out in relief.
•A hammer presses the wheel against a ribbon, which in turn makes an ink stain in the shape of the character on
the paper.
•Daisy-wheel printers produce letter-quality print but cannot print graphics.
Dot-Matrix
•Creates characters by striking pins against an ink ribbon.
•Each pin makes a dot, and combinations of dots form characters and illustrate
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Non-Impact Printer
•It uses ink spray, toner powder or inkless
Advantages
•Quiet
•Can handle graphics and often a wider variety of fonts than
impact printers
•Fast
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Disadvantages
•More expensive
•Occupies a lot of space
•The cost of maintaining it is high
Multifunction Printer (Toner-based)
•An MFP is an office machine which incorporates the functionality of multiple devices in one.
•A typical MFP may act as a combination of some or all of the following devices:
–Printer
–Scanner
–Photocopier
–Fax
Ink-jet Printer
•Inkjet printer operates by propelling variably-sized droplets of liquid or molten material (ink) onto almost any
sized page.
•They are the most common type of computer printer used by consumers.
Thermal Printer (Inkless)
•Thermal printers work by selectively heating regions of special heat-sensitive paper.
•These printers are commonly used in calculators and fax machines; and although they are inexpensive and
print relatively fast, they produce low resolution print jobs.
Printing Speed
The printing speed is measured in:
 cps (characters per second)
 lpm (lines per minute)
 ppm (pages per minute)
Plotter
 The plotter is a computer printer for printing vector graphics
 Plotters are used in applications such as computer-aided design such as diagrams, layouts, specification
sheets and banners
 The plotter is capable of producing color drawings in a matter of minutes
 Plotters differ from printers in that they draw lines using a pen
 Plotters are considerably more expensive than printers
Speakers
 A hardware device connected to a computer's sound card that outputs sounds generated by the computer.
 Speakers can be used for various sounds meant to alert the user, as well as music and spoken text
Headphones
 Headphones give sound output from the computer.
 They are similar to speakers, except they are worn on the ears so only one person can hear the output at a
time.
Projector
 An output device that can be directly plugged to a computer system for projecting information from a
computer on to a large screen
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Useful for making presentations to a group of people with direct use of a computer
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Full-fledged multimedia presentation with audio, video, image, and animation can be prepared and made
using this facility
An output device that can take the display of a computer screen and project a large version of it onto a flat
surface.
Projectors are often used in meetings and presentations so that everyone in the room can view the
presentation.
Types of projector
•Cathode Ray Tube (CRT) projector
•Liquid Crystal Display (LCD) projector
•Digital Light Processing (DLP) projector
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STORAGE DEVICES
A storage device is any computing hardware that is used for storing, porting and extracting data files and
objects.
 It can hold and store information both temporarily and permanently, and can be internal or external to a
computer, server or any similar computing device.
 A storage device may also be known as a storage medium or storage media.
 Storage devices keep information for later use
 Information is stored by the computer on storage media
Examples of storage media
Hard drive, floppy disk, compact disk (cd), zips drive, memory cards, memory stick and magnetic tape drive and
online storage.
HARD DISK
it is found in system unit
•hard disk drive is the main, and usually largest, data storage device in a computer.
•it can store anywhere from160gigabytes to 2terabytes.
•hard disk speed is the speed at which content can be read and written on a hard disk.
COMPACT DISC (CD)
Compact disk is a storage device which keeps information and music
 Played on computer, DVD player or a radio
 some cds are read only( CD -ROM)-data can only be once i.e. once the pits are burnt on to the surface ,that
part of the disc cannot be used again for storage although it can be replayed endless times.
 Some are rewritable (CD-R) - this means you can save the data over and over again
ADVANTAGES OF CDS
 small and portable
 very cheap to produce
DISADVANTAGES OF CDS
 fairly fragile, easy to scratch
 very cheap to produce
 smaller storage capacity than hard drive or dvd
 needs to be protected from heat
DIGITAL VERSATILE DISC (DVD)
 A disc capable of storing large amounts of data on one disc the size of a standard compact disc.
 Today they are widely used for storing and viewing movies and other data.
 A DVD is capable of holding any data and are most often used to store movie data, games, and install data
for programs.
 Can be easily break
 Store very large capacity of data
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 They are also cheap
 Sound and picture quality is good and why they used to store films
 Easily break like cd
WHAT IS THE DIFFERENCE BETWEEN A DVD AND A CD?
Physically, a DVD and cd look the same both discs are the same size and typically have one side with a
label and the other side that the laser reads, unless it is a double-sided DVD. However, the technology that
makes up a DVD allows for the same size disc to hold a lot more data than a cd.
MEMORY CARD
 Flash memory cards are small storage devices that are used to store the data backups such as the text , the
pictures , audio, and video , They are more compact and portable than CDs or DVD , And they can hold
more data than a CD , many gigabyte
 a storage media which stores memory
 These are commonly used in portable electronic devices, such as digital cameras, mobile phones, laptop
computers, tablets, mp3 players and video game consoles.
 memory cards are solid state media , They are free from mechanical difficulties or damages , They are
small , light and compact with high storage capacity , And they require less amount of power .
DISADVANTAGES OF MEMORY CARDS
 Memory Cards can break easily ,
 They can be lost , misplaced or smashed easily ,
 They can be affected by the electronic corruption , and they make the entire card unreadable ,
 They are more expensive than CD or DVD ,
 The metal part can be snapped off or damaged if they are handled roughly .
USB MEMORY STICK
 Solid way of storing data
 Most USB flash drives are removable and rewritable
 Physically, they are small, durable and reliable. The larger their storage space, the faster they tend to
operate
 Mistakenly referred as to usb
FLOPPY DISK
 a flexible removable magnetic disk, typically encased in hard plastic, used for storing data
 not commonly used nowadays
 available in 3.5 inches floppy 5.25 inches floppy 8 inches floppy
Advantages:
1) Floppies are cheap and can be used many times
2) Floppies are easy to transport and handle
Disadvantages:
1) Floppies don’t have much storage capacity
2) Floppies can get affected by heat
3) They have to handle more carefully
MAGNETIC TAPES
Definition - What does Magnetic Tape mean?
 Magnetic tape is a type of physical storage media for different kinds of data
 Magnetic tape is one of the oldest technologies for electronic data storage.
Advantages
 A single magnetic tape cartridge can store large amounts of data up to 1 Terabyte. Large cartridges are used
by big companies and institutions that require continuous recording and backup of data.
 Data collection can go on without interruption overnight or for an entire weekend.
 Magnetic tape can be recorded over and reused repeatedly.
 Large amounts of information are stored.
 Magnetic tape is inexpensive and budget friendly.
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Disadvantages
 Special equipment must be purchased and set up for recording and storing data. The data can only be read
on the special equipment.
 If the data is stored near a strong magnetic field or a large speaker, the tape can be damaged.
 Magnetic tape has a lifespan of 15 years. Data quality gradually erodes over time.
 It is necessary to keep older tape equipment just to be able to read the stored data.
CLOUD STORAGE
 Cloud storage means the Storage of data online in the cloud, “Wherein data is stored in and accessible from
multiple distributed and connected resources that comprise a cloud.
 Cloud storage can provide the benefits of greater accessibility and reliability; rapid deployment; strong
protection for data backup, archival and disaster recovery purposes
EXAMPLES:
 Google drive
 flicker
 Microsoft skydive
 drop box
Application of hardware devices
Point of sale (POS) terminal
 Electronic device used to process electronic payments at retail locations.
 May work together with a bar code reader to determine if item names and prices.
 Generally has its core a personal computer, which is provided with application specific programs and
I/O (input and output) devices for the particular environment in which it will serve
 POS in a restaurant is likely to have all menu stored in a database that is accessed to retrieve
information to do with prices of food items and others. It typically does the following
 Reads item name and price
 Reads the information on customer's credit or debit card.
 Transfer funds from customer account to the sellers account ( if the card has sufficient funds,
otherwise reject the transaction).
 Records the transaction and prints a receipt.
 Regardless of the software used, every POS should at least have the hardware below:
a) Register screen
A standard monitor that displays the product database
The device also enables other functions such as employee clock in and viewing sales reports.
b) Barcode scanner
Scanning barcodes pull out product information (name and price) from the database and adds it to
receipt total.
Barcodes may be interested with inventory or stock management systems to automatically adjust
stock levels when an item is scanned.
c) Receipt printer
Prints customer receipt
d) Card reader
Enables the POS to facilitate electronic payments made by debit or credit card
Automated Teller Machine (ATM)
 Is an automatic banking machine that allows bank customers to bank customers to access their
accounts without any help from a bank teller
 Customers have a magnetically encoded plastic card and a pin(Personal identification number) to
perform ATM transactions
 They can perform the following on an �
 Withdraw cash
 Pay bills
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Make deposits
Obtain statements
Effect bank transfers
Components of an ATM
a) Input device
 Card reader
An input device that reads data from a card when inserted into the machine
Card reader is part of the identification of you particular account number and the magnetic strip on the
backside of the ATM card is used for connection with the card reader.
The card once swiped or pressed on the card reader or inserted in the card reader which captures your
account information.
Data from the card is passed on the host processor server.
The host processor, thus, uses this data to get information to get the information from the card holder.
 Keypad
The keypad enables the ATM user to enter their PIN or amount they would like to withdraw. It also
has an enter key that communicates whether to approve the requested transaction and delete and cancel
facility that cancels any transaction. Some keypads are touch screens.
b) Output devices
 Speaker
Most advanced � s has a speaker facility that provides audio feedback when a particular key is pressed.
This of benefit to the blind as they can do their banking without any help
 Display screen
Displays the transaction information
Each step of withdrawal is shown by the display screen.
Leased line machines commonly use monochrome or colour crt (cathode ray tube).
Dial up machines use a monochrome or LCD (liquid crystal display) for their screens.
 Receipt printer
Prints all the details of transactions such as date and time, the amount withdrawn and balance of your
account
 Cash dispenser:
Central system of the ATM machine where the required money is obtained
Counts each note and give the required amount.
This action is carried out by Hy prediction sensors. A complete record of each transaction is kept by
the ATM with the help of a Real time clock (RTC) device.
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Data capturing systems
An electronic data capture (EDC) system is a computerized system designed for the collection of data in
electronic format.
EDC solutions are widely adopted by pharmaceutical companies and contract research organisations (CRO).
Some of the most fundamental EDC functionalities comprise of quality checking of already collected data,
allowing researchers to enter data into a centralized database and forming web- based data entry forms.
Typically, EDC systems provide:
A graphical user interface component for data entry.
A validation component to check user data.
A reporting tool for analysis of the collected data.
Examples of Electronic Data Capture systems include:
Medrido
Castor EDC
Aetiol
Datalabs
Poimapper
Advantages of EDC
Allows logic checks to highlight discrepancies to site during data entry.
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Data can be reported in real-time, ensuring safety data are readily available for central review,
advantageous for high risk- risk trials.
Queries can be sent instantly with reduced turnaround times for data clarification.
Using EDC reduces paper management time require less physical storage space.
Disadvantages of EDC
Specific training is required and site staff needs to be encouraged to submit data immediately following
participants visits, instead of batching data entry.
Database user access and internet browser compatibility monitoring systems are required to ensure only
current site staff have access and are using a supported browser.
SOFTWARE
Software can be defined as the programs/instructions that make the hardware to work.
Set of programs that contains instructions that tell the computer what to do and how to perform each task.
Classes of software
They are two classes
Systems Software and Application Software
APPLICATION SOFTWARE
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Refers to programs that enable the user to achieve specific objectives e.g. creating documents, spread
sheets, designing.
It is classified in to categories
 General purpose software
 Special purpose software
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General purpose software
Software that performs general tasks
Tasks that can be done by anyone regardless of their profession or area of specialisation.
In this category belongs the following:
Word processing software e.g. Microsoft (Ms) word.
Spreadsheets e.g. Microsoft (Ms) Excel
Database Management Software e.g. (Ms) access
Presentation graphics e.g. Microsoft (MS) power point
Dtp Desktop Publishing e.g. Microsoft (Ms) publisher
Special purpose software
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Refers to application software that is meant for use by professionals in specific industry like mining,
hospitality, transport, agriculture, banking and insurance, retail and medical.
 NB Take note people in these areas need general purpose software to perform certain tasks such as word
processing or presentation.
 Programs dedicated to very specific functions within a knowledge area of profession such as accounting,
engineering, manufacturing, transport and logistics, statistics
There are two ways of acquiring software
 Off the shelf software
 Customized software
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Off the shelf software
Ready-made software that you purchase .e.g. Microsoft Office
Characteristics of off the shelf software
Sold in stores can be sold on the Internet.
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 Installation can be standard or custom.
 Can be purchased, installed and used immediately.
 Written to solve specific problem.
 Can be designed to do one particular task e.g. payroll, stock control
Advantages
 Less expensive than custom written because of economies of scale
 Readily available since it can be bought from a shop or the internet and installed right away.
 Large user base that is available in the form of advice forums, 3rd party books and training courses. In
addition staff may be already be familiar with software.
 Software is tried and tested therefore there are fewer bugs than newly written software
 Runs on a wide range of hardware
Disadvantages
 Ownership can be high due to license and upgrades.
 Software may not completely fit the task since it would have been developed for a wide range of customers.
 Software may have too many additional unwanted extras.
Customised software
 Specifically developed for some specific organisation or user.
 Also known as tailor made software.
 Also known as bespoke software.
Characteristics
 Takes a lot to time to write and test since requirements would be unique.
 Designed and written specifically for one company.
Advantages
 Designed to do exactly what the user wants.
 Can be written to run on user-specified hardware.
 Can be interested with existing software.
Disadvantages
 Time consuming to have it developed
 Expensive since the one customer has to pay for all expenses. There are no economies of scale.
 There is limited support since nobody else would be using that software. 3rd part books not likely to be
available.
 New staff unlikely to be familiar with software.
Systems software
 A group of programs (software) that is almost always sold together with the computer.
 It helps you manage and control the hardware of your computer system.
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SYSTEMS SOFTWARE
Refers to a group of programs (software) almost always sold together with the computer. In other words, it helps
you manage and control the hardware of your computer.
It also provides an interface between you and the computer.
To every computer software for it to be able to run
Operating System (OS) is a part of systems software that provides a communication medium between application
software and computer hardware. E.g. Windows 10, Linux, MacOs desktop computers and laptops, while Android
for smartphones.
Utility software these are programs that are used to manage computer system effectively.
Language translators are also known as Systems Development software. These are programs used to develop
software (system and application software). System Development software is also referred to as programming
languages.
A programming language is a language used to write software and understood by computers. Examples are Java,
Visual Basic, Python and C etc.
Programming language understood by computers that is used to write software.
Programming is the process of writing (developing) computer instructions (software).
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Programmer is the one who develops computer software.
Examples include java, visual basic, python C, C#, java script, html, php etc.
It can be divided into three categories namely
 Operating system
 Utilities
 Language translators
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Operating System
Is the part of systems software that provides a communication medium between application software and
computer hardware.
 It ensures connectivity between hardware of computers and the application software
Examples are Windows 10, android, Linux, and apple iOS etc. Operating systems
 Operating System and utility software belong to the category of systems software.
 Though different Operating systems are available for computers performing similar functions. Most of
these functions are performed automatically in the background, often without the users’ awareness.
 Basic minimum software that a computer needs for it to function.
 Provides a user interface that allows that allows one to work with the computer.
 Manage all the hardware resources
 Provides a platform for managing files and application programs.
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Functions of operating system
Manages the computer resources, such as the CPU, memory, disk drives, and printers.
Provides the foundation for application software to be launched.
Establishes a user interface
Determines the to types of application software that can be installed.
Coordinates the applications running on the computer at any given time.
Reports errors such as printer out of paper, software error etc.
Executes and provides services for application software.
Manages the computer’s memory and processes, it is sometimes referred to as a task manager.
Also called a device manager because it controls how input and output devices (hardware) function on a
computer system.
 Allows the user to communicate with the computer. It is an interface between the user and the computer
Below are more functions of an operating system:
1) Routes data between the hardware resources and the application programs.
 It provides device drivers or refers the user to install a specific driver.
2) Booting/ starting the computer
 Starts the user interface and properly shuts down the hardware.
 Instructions for booting are stored on the Basic input output system (BIOS) chip that resides on the
motherboard.
 They are two basic ways of starting a computer cold boot and warm boot.
 Cold boot refers to turning on a computer that has been shut down.
 Warm boot refers to starting a computer without turning of power.
 A proper shutdown command is recommended so that programs and files are properly closed.
 During booting depending type of os a message is displayed on the screen.
 Upon completion of booting the user interface or the login screen will display.
3) Providing a user interface.
 User interface (UI) refers to the means which you interact with the computer.
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 They are two types of interfaces, namely graphical user interface and command line interface. A GUI
presents visual images such as buttons, tiles or icons that you tap or click to tell the OS what you want
to do whilst a CLI requires that you type
 commands onto a prompt such as c:\users\firstname using a keyboard
 Network specialists will sometimes use a CLI to configure or troubleshoot a network device.
Managing application programs and coordinating the flow of data.
 Manages the installed programs and allows you to run, install and uninstall programs.
 It provides a task manager thereby it manages computer resources.
 It allocates data to and software to or from the CPU as needed.
 Manages the CPU, cache memory, Ram, input, output devices.
Configuring hardware and peripheral devices.
 Configures all devices that are installed or connected to the computer.
 Each device requires specific software known as driver software for it to properly function on a
computer.
 Examples are printer drivers, sound drivers etc.
 Normally drivers are supplied by manufacturers and usually come as a CD.
 In some cases operating systems already provides some of the drivers.
 Plug and play refers to a situation where the driver is readily available.
Providing a file system
 Keeps track of files stored on the computer.
 Provides tools for managing files.
 Copying, renaming, moving or deleting.
 Utility programs restore, clean up, search, defragment storage devices and back up files are included in
the OS package.
Software updates and security.
 If permitted it automatically downloads available updates
 It provides program fixes, security enhancement and updates of device drivers
Types of operating systems
 They are several categories of Operating systems that are used in the field of computing.
 One way is by considering if they are used on networks or not.
Based on this classification we have.
a) Standalone Operating systems
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Is the one that works on a desktop?
 Provides its services to just one computer at a time.
 Examples: windows 10 home, windows 7 enterprise.
b) Network Operating Systems (network OS or NOS)
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Designed to support computers and peripherals devices connected in a network
 Enable sharing the sharing of data files, application programs and other services such as printing, over a
Local Area network (LAN)
 Example: windows 2000 server, UNIX, NetWare, Linux and Windows .net etc. etc.
c) Embedded Operating Systems
 Designed for embedded systems.
 Embedded systems are specially designed computers that are found inside other gadgets or equipment.
Examples of embedded systems are mobile phones, washing machines, microwave oven, ATM and digital
camera to mention a few.
 Examples of embedded operating systems are: palm os, Android OS, Windows CE, iOS, Symbian, pocket
PC 2002.
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Personal computer operating system
It depends on the hardware because some hardware is designed for specifically for a particular OS.
Mac books and apple computers are compatible with mac OS
The OS should be compatible with the hardware in terms of in terms of data bus size.
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A 64 bit OS cannot be installed on a computer less than 64 bit.
Utilities
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Software programs that are used for effectively managing a computer system.
They can be referred to as housekeeping tools.
Programs which improve the functioning of the operating system or supply missing or additional
functionality.
They perform the following tasks.
 Backing up files.
 Compress files e.g WinRAR, WinZip, power iso.
 Decreasing the size of files, resulting in faster downloads.
 Searching for and managing files.
 File management functions such as: copy files; determine how and where files are stored and delete files.
 Search utility. To
 Providing antivirus software protection - antivirus software protects the computer from viruses. Examples:
are bit Defender, Kaspersky, Norton and set nod32 antivirus.
 Help utility.
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Language translators
A Translator is a program that translates a source program/code into an equivalent object code [machine
code] before the program is executed by the computer.
System development software fall under this category.
Used to develop software (systems and application software).
HARDWARE and SOFTWARE MAINTENANCE
 A computer is functional if hardware and software are working properly computers just like any other
machines sometimes get faulty and fail to function
 This means either hardware or software can malfunction.
Relationship between hardware and software
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Hardware and software are mutually depended on each other
Hardware without a set of instructions cannot be utilized hence it’s of no value
Software can also not be utilized without supporting hardware
In order for proper functionality of the computer relevant software should be installed on to the appropriate
hardware
 Every device of hardware requires a device driver so it can function properly
Device Driver
 Program(software) that controls a particular type of device that is attached to your computer
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Troubleshooting
A systematic approach to problem solving that is often used to find and correct faults with computer
systems
The first step is to gather enough information on the issue, such as undesired behavior or lack of expected
functionality
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COMPUTER NETWORKS AND INTERNET
TECHNOLOGIES
Computer networks
 Refers to a collection of computers and other devices connected together in order to communicate.
 A network can be as small as just two devices connected or as big as millions or more computers connected.
 Networks can be wired or wireless.
Reasons for networking
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Sharing information
Sharing resources (such as printers)
Sharing communication such as receiving and sending emails.
Networks can be wireless or wired, depending on the medium of communication.
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Expensive peripherals like printers and scanners can be shared between users.
Messages can be sent easily and faster between users whether on WAN or LAN.
Avoids duplication of information as users can access the same file on the network
Network software can be purchased cheaply than buying individual packages for each computer.
It is possible to access data or programs from any terminal or workstation.
Data and programs can be stored centrally making it easier to maintain and backup.
Users can be easily prevented from accessing files not intended for them.
Allows sharing of files, software and data held in computers
Allows emails to be send between users
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Advantages of Networking
Disadvantages of Networking
Sophisticated equipment is needed, which may be expensive to buy.
Security of data can be a problem due to hacking.
Wiring can be expensive both to buy and to install; wiring can be sunk on the ground to avoid trailing
cables.
If a server breaks down, the whole network becomes unusable.
Networks need experienced network managers, who will be highly paid to keep the network running
Network architectures
Client a computer that requires service from another computer on a network
Server a computer that processes the request and sends back a response
 Network: A connection of computers for them to share data, files and resources like a printer the client.
 Host a computer connected to a network of computers.
 Data communication: The process of transferring data through networked computers
 Some networks have specific computers designed as servers, while others do not.
 In a network where no specific computers designed as a server, every computer can assume the role of a
server or client depending on whether it is requesting a service or processing a received request or
processing a received request to fulfill it, respectively.
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Peer to peer network
A network that does not have designated services.
Client/Server
Is a network that does not have designated server
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Classification of networks
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It is often based on the hardware and software technologies used to interconnect the computers and the
geographical coverage.
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-Computer networks are grouped into Local Area Networks (LAN) and Wide Area Networks (WAN).
-However we also have WLAN (Wireless Local Area Networks), MAN
(Metropolitan Area Networks) and PAN (Personal Area Networks); and these are described below.
Classes of Networks
LANS and WANS
Local area network
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Covers a small geographical area
Examples: office, house, classroom, lab hotel, university or school.
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Covers a small geographic area
Pan can be as small as a phone connected to a laptop to share files.
Pan and can
Wide area network
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A computer network that covers a broad geographical area
Any computer network whose communication links span city, town/metropolitan, regional or national
boundaries
NB bank network
 The largest WAN covers the world.
 Man metropolitan area network
 Spans across city or town
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Network topologies
Topology refers to the arrangement or layout pattern of computers and other devices in a computer network
Also called network architecture
It can be physical or logical
They are named on how computers are arranged in that network
Devices on a network are called nodes or hosts
Nodes includes VOIP ( voice over internet protocol) phones, computers and peripheral devices like printers
Topologies include
Star, Ring, Bus, Mash
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Bus topology:
A network topology in which each workstation is connected to a main cable (backbone) through which the
network is established.
The Backbone acts as the common medium; any signals sent or received go through the backbone in order
to reach the recipient.
Star topology:
A network topology in which each workstation is connected to a central node/connection point through
which the network s established
The central node (hub) re-directs and directs the packets according to the data traffic and their recipient.
Ring network topology
Computers are connected together to form a circle and uses a token when transferring data.
Data/information travels in one direction only.
Information moves around the ring in sequence from its source to its destination.
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As data passes from one computer to another in the ring, each computer removes any data relevant to it and
adds any data it wishes to send.
The diagram below illustrates the physical configuration of a ring network:
Advantages of Ring Network
Data processing is faster as each computer processes its own processor.
Has very high data transfer rates.
Uses a token to avoid data collision or loss
It is possible to create large networks using this topology
If one computer breaks down, others will remain working as they have their own processors and storage
facilities.
Performs better than star network when traffic is very heavy
Disadvantages of Ring Network
If one computer breaks down, the whole network is disrupted.
a faulty connection between two stations can cause network failure
Its requirements are expensive, that is buying several computers with processors and storage facilities.
It is difficult to link the computers together.
Difficult to add another computer without disrupting the networking
Only the computer with the token is allowed to send data at a given time. One may not send data when
another node (computer) is still sending its own data.
System is less secure as token together with data has to pass through other nodes that do not concern it.
Mesh Network
A network in which each computer serves as a relay point for directly sending information to any other
computer on the network
No central device oversees a mesh network, and no set route is used to pass data back and forth between
computers.
Thus, if any one computer is damaged or temporarily unavailable, information is dynamically rerouted to
other computers—a process known as self-healing
Advantages of Mesh Network
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If one computer breaks down, others will remain functional.
If one computer breaks down, the network is not disturbed.
Computers have their own storage and processing capabilities.
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Expensive to buy computers with their storage and processing facilities
Too much cabling is involved, which may be expensive.
Disadvantages of Mesh Network
INTERNET SERVICES
These include email, e-commerce, e-learning and social media
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Email
Long back mail was sent by post
Short for electronic mail
Used to send electronic messages over the internet
It real time meaning the message is delivered there and then
Examples of companies that that offer email services
Gmail, yahoo, cool toad and many more
E-commerce
The buying and selling through the internet
It does not have geographical limitations
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You can buy and sell in the comfort of your home
Payments can be done virtually or online using credit cards master cards, mobile money transfer or you
have to visit the bank
Advantages of e-commerce
 Buying and selling is 24hr a day and 7 days a week (24/7)
 Eliminates travelling costs to make a purchase
 No time wasted in queues
 Transactions can be done by several people simultaneously
 Reduces the risk of moving around with cash
E-learning
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The short for electronic learning
Also referred to as online learning, computer mediated learning, web based learning, and technology
mediated learning or virtual learning
 A computer based learning and teaching system that enables people to learn from anywhere at any time.
 Learning conducted via the internet or any other electronic media
 You can learn anywhere from anywhere
 Examples websites, social media platforms YouTube
Advantages of e-learning
 You learn from anywhere at any time
 You can self-pace your learning depending on learner speed and commitment
 It can be interactive, engaging and effective
 It reduces cost of learning
 It is flexible in terms of time tables
 Learning can be fun for example gaming
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Social media
Refers to internet based applications and tools that facilitate the creation of tools that facilitate the creation
and sharing of information, ideas and other forms of expression among people and communities
Members who participate in a particular social network form a virtual community
While it presents seems to emphasize on defining social interactions it is being used for other purposes like
marketing, learning and many more.
DATA TRANSMISSION
 Is the process of transmitting or transferring data between two or more digital devices connected on a
network?
 It allows devices to communicate with each other
 During communication, computer data is transmitted between e sending and receiving computers.
 The mechanism is called data transmission modes
 They are three modes of data transmission.
 They are three modes of data transmission
Data transmission modes
Full duplex/Duplex
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Simultaneous transmission of data in both directions
It is both bidirectional and simultaneous
The channel can transmit data signals in both directions on one signal carrier simultaneously
One example is a mobile phone
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High transmission speed
Improved communication efficiency due to simultaneous sending and receiving of data signals.
Advantages of Duplex
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Half Duplex transmission modes
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Sending and receiving of data is bidirectional but not simultaneous. When the other end is receiving the
other end should be transmitting
Example walkie talkie
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Cheaper to extend over long distances
Since data is transferred over a single wire
Fewer wires are required when extending it.
Though they is need for electric components the electric components are cheaper
There is no wire timing problems caused by different wire lengths. Unlike in parallel
It is cheaper than full duplex since it uses one channel for both sending and receiving.
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The flow of data is unidirectional
Common example is a radio station
Radio stations send signal to their audiences but never receive signals from them thus the data transmission
is one directional
In computer networks it is common on fiber optic communication
One strand is designed for sending signals only and the other one for receiving signals
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Entire bandwidth can be used during transmission
Cheaper in hardware since there is no need for receiving channel but sending only.
Advantages of Half Duplex Transmission
Simplex transmission
Advantages
Data transmission media
 It is the pathway through which data is transmitted or carried between the sender and the receiver (medium
in singular and media in plural).
 Normally data is transferred in electromagnetic signals
 Electric signals are in the form of electric current whilst electromagnetic signals are a series of
electromagnetic energy pulses at various frequencies.
 Transmission media can also be referred to as communication media.
It is classified in to two bounded and unbounded media
Bounded media are also called guided or wired whilst unbounded are also known as unguided or wireless
Bounded media
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Any data transmission medial that confines data signals to a specific path using a wire cable. It is therefore
referred to as wired medium
 Any data using wire or cable, it is therefore referred to as wired medium.
 Data signals traversing bounded media are directed and contained by the physical limits of transmission
media
Examples
 Fibre optic cable
 Coaxial cable
 Twisted pair cable
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Twisted pair cable
Copper wires are cheaper and are of good performance hence they are commonly used.
However, they are susceptible to signal interference if at least two wires are lying together.
The signal interference is known as electromagnetic interference and may result in distortion of
communication
To reduce the electromagnetic interference in copper cables, pairs of of copper wires are twisted together,
hence the name twisted pair cables
Ethernet cable is an example
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Characteristics of twisted pair cables
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It is relatively cheaper
It has low noise immunity
It can be affected by external magnetic interference
It has the lowest bandwidth compared to coaxial and fibre optic cables
Maximum cable length between hub and computer is 100m
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It is an insulated copper wire with mesh wire shielding and insulating cover.
May be reoffered to as coax
It has high capacitance, meaning it has good signal propagation
It has low magnetic interference (low noise), it is bulky and stiff to bend.
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It has higher immunity to noise than twisted pair.
It is less affected by external magnetic field
It is more expensive than twisted pair cable but less expensive than fibre optic cable.
It has higher bandwidth than a twisted pair cable but lower than a fibre optic cable
The maximum cable length between hub and computer is 500m
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It is similar in construction to the coaxial cable but it is faster and more expensive
It has a narrow strand of glass core, plastic buffer, Kevlar cushion and plastic shield. It has a very high
transmission speed and very high capacity.
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it is highly immune to noise since it is not affected by electrical noise
It is not affected by electromagnetic interference.
it is the most expensive compared to twisted pair and coaxial cables
it has a very high bandwidth
maximum cable length 80km
Coaxial cable
Characteristics
Fibre optic cable
Fibre optic cable characteristics
Unbounded transmission media
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Data signals flow through the air.
Oftenly referred to as wireless transmission.
Data signals are not guided or bounded by a physical channel to flow
Therefore are three types: Radio transmission, microwave transmission , and satellite transmission
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It is the sending of data signals through air by modulating electromagnetic wave frequencies below usable
light .It carries data signals over relatively long distances.
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Radio frequency (RF) waves are relatively easier to generate
They travel long distance unlike microwave
RF can easily penetrate building s .They can travel in an direction from the source , thus there no need for
careful physical aligning of transmitter and receiver
They are prone to interference from electrical equipment.
Behavior of RF waves is dependent upon frequencies. They tend to travel in straight lines and bounce off
obstacles when frequencies are high, whereas they pass through obstacles at low frequencies are high,
whereas they pass through obstacles at low frequencies very well
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Radio transmission
Characteristics of radio frequency transmission
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Microwave transmission
Refers to a straight line of sight transmission since transmitting station and sending station must be in
visible contact. This places a distance limit of about 50km between sending and receiving stations
The range of operation is between 3 GHz and 10 GHz. These high operating frequencies allow microwave
transmission to carry a large quantities because of their bandwidth
As distance between sending and receiving channel's increases, signal strength reduces. Repeater stations
must be installed to revitalize the signals
Satellite transmission
Uses electromagnetic waves as carrier signals to transmit data between ground and space vice versa
An unobstructed line of sight between the orbiting satellite and a station on earth is required for satellite
transmission
Although they travel in straight line they are not affected by such factors such as the Earth's curvature as in
the case of ground-based wireless transmission.
Internet service providers
ISP stand for internet service provider
It's a requirement to connect to the internet
It is a company that allows its clients to connect to the internet
They are also known as IAP internet access provider
Examples net one econet and powertel etc. etc.
Services offered by ISPs
Act as an interface between customer computer system and the internet. This is usually done through dial
up services, DSL digital subscriber line service and cellular data service
Provides a direct link between organisation network and the internet
Provides service such as electronic mail email, web hosting and also designing
Connect clients to the nearest internet gateway.
Provide modem for dial up connections
Provide security to their clients. It is archived by stopping spread of viruses and malware by applying
antivirus systems for their clients
Mobile technologies
 Refers to � battery powered information and communication technology
 Mobile technologies includes both software and hardware
 They include smartphones, satellite, PDAs personal digital assistants, tablets and laptops
Mobile phone
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A portable handheld wireless phone that uses a cellular radio system over a wide area
They are categorised into two. Feature phones and smartphones
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It is limited in functionality. Primarily allows one to make calls and send text messages and generally does
not allow users to connect to the internet
Feature phone
Smartphones
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Has more functionality than a feature phone
Runs software and applications which cannot run on a feature phone
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Refers to a wireless communication technology used to transfer signals between the transmitter and
receiver by using satellites
They are used for radio broadcasting in mobile communication
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Satellite communication
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PDA Personal digital assistant
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Also called a hand held personal computer and functions more like a personal information manager
It combines features, including computing, telephone/fax, internet and networking.
It can be used as a mobile phone, personal organiser, web browser and � fax sender
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It is a touch screen, a wireless, mobile device smaller than a laptop but larger than a smartphone. It is called
a tablet PC, though commonly shortened to just tablet. One can virtually everything that one can do on a
PC
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Are used in almost every facet of daily life. It is applied virtually in all most all sectors you may think of
Refers to electronic devices that communicate through the air using radio frequency signals. In wireless
technology communication takes places without cables.
Mobile technology hinge on wireless technology which provide greater mobility.
Some wireless technologies covers a short distance whilst others cover long distances
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Mobile technologies help in communication
Provide easy access to agricultural and market information.
Provides e banking ecommerce e insurance to farmers
Examples include Eco farmer, farmers club Telecel and Murimi Umlimi Rubiem tech
E agriculture or e farming are a result of the applications of mobile technology in agriculture
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Refers to the exchange (transmission or conveyance) of information between two or more people by
whatever means, such as writing, talking or any other means.
Wireless technologies are widely used in communication. Whatsapp, Facebook, calls and texts are used
every day globally
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Used for recording playing and editing music and videos
People can also buy and sell their services on the internet
Tablet
Application of mobile technologies
Agriculture
Communication
Entertainment
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Education
Mobile learning
M-learning or mobile learning is a form of distance education where learners use portable devices such as
mobile phones to learn anywhere at any time. The portability that mobile devices provide allow for learning
anywhere, hence the word "mobile" in "mobile learning". M-learning devices include computers, MP3
players, mobile phones, and tablets. M-learning can be an important part of informal learning. M-learning
is convenient in that it is accessible virtually anywhere.
 M-learning allows for the instant sharing of feedback and tips since the mobile devices are often connected
to the internet. M-learning also brings strong portability by replacing books and notes with small devices
filled with tailored learning contents. M-learning has the added benefit of being cost-effective, as the price
of digital content on tablets is falling sharply compared to traditional media (books, CDs, DVDs, etc.).
 It offers some possibilities, such as greater and different access to information. It also offers transcendent
innovations, such as the increase of informal and playful activities, iconic virtual membership, and
networks of friendly interaction within new scales of values
 *Here's some stuff you might want to know*
How does mobile technology help with education?
 Mobile devices allow students to connect, communicate, collaborate, and create using rich digital resources.
Learning to be comfortable with such devices prepares students for shifts in the global economy and helps
them adapt to quickly evolving new technologies.
What is an educational mobile application?
 Any mobile software that can be a remote learning platform is called an educational app. This integrated
learning system offers complete knowledge and end-to-end learning solutions.
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What is mobile technology in the classroom?
 Mobile learning seeks to utilize the ubiquity and unique capabilities of mobile devices to make course
materials available to students wherever they are, and to create new kinds of learning experiences that help
students engage with course content and the world
Mobile shopping
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M shopping refers to the buying and selling goods and services through mobile (handheld) devices such as
laptops, tablets and smartphones
 You can buy and sell virtually anything in the comfort of your home, hostel, office or car.
Advantages
 You can shop online at any time, from anywhere. Whether you're sitting at home on the couch or waiting
for a bus, you can easily browse products and make purchases with just a few taps on your phone
 Eliminating the risk of moving around with cash since payment is done remotely and digitally using plastic
money in most instances
 Saves on travelling and subsistence costs and time.
 It is convenient
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Mobile banking
Use of mobile devices in banking
Banking is no longer confined to the banking walls and working hours of the banking staff.
Mobile marketing
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A digital marketing strategy where audiences are reached via emails, social media, texts messages and
applications such as Pindula
Advantages of mobile marketing
 Huge audience can be reached
 Cheaper since they is less paper work and can be done online
 Modern society spends much of its time on mobile devices
Disadvantages
 Scams
 Pop up messages adds they irritate internet users
Wireless technologies
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WiFi
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Some texts write it as Wi-Fi
Wi-Fi is an acronym. It short for wireless fidelity
The technical name is IEEE802.11
It’s a universal wireless technology that uses wireless technology that uses radio frequencies to transfer
data and allow high speed internet connections without using cables
It operates in an unlicensed 2.4 radio bands with 11Mbps (802.11b) or 54Mbps (802.11a) data rates
respectively. Mbps is short for megabits per second.
A Wi-Fi enabled device is needed to be able to connect to a Wi-Fi
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Stands for worldwide interoperability for microwave access
A wireless broadband communication technology that is based on the IEEE 802.11 standards
It eliminates the need for wires by ISPs to provide internet connectivity to its clients
They do it wirelessly by providing base stations
Unlike WiFi which is local area network, WiMax is for wide area network
Its speed can get unto gigabits per second
It can run on both licensed and unlicensed spectrum whereas WiFi only runs on unlicensed spectrum
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WiMax
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Bluetooth
It is a short range wireless communication technology
Commonly used share files and connect to audio devices
A network of devices connected to a Bluetooth is called a mobile ad hoc network (MANET). The
network is self-configuring and infrastructure-less
Infrared
It is abbreviated IR, a wireless short range communication technology
It is line of sight mobile communication technology
Line of sight refers to a communication technology that requires the transmitter and receiver to be in visible
contact for communication to take place
It cannot penetrate through wall or other obstacles
Microwave
Refers to line of sight transmission since the transmitting station and receiving station should be in visible contact
It places a distance limit of 50km between the sending and receiving station
As distance between sending and receiving station increases, signal strength reduces
Communication protocols
 A communication protocol is a system of rules that allows two or more entities of a communications
system to transmit information via any kind of variation of a physical quantity. The protocol defines the
rules, syntax, semantics and synchronization of communication and possible error recovery methods.
Protocols may be implemented by hardware, software, or a combination of both. Communicating systems
use well-defined formats for exchanging various messages.
 Each message has an exact meaning intended to elicit a response from a range of possible responses predetermined for that particular situation. The specified behavior is typically independent of how it is to be
implemented. Communication protocols have to be agreed upon by the parties involved. To reach an
agreement, a protocol may be developed into a technical standard.
 A programming language describes the same for computations, so there is a close analogy between
protocols and programming languages: protocols are to communication what programming languages are
to computations. An alternate formulation states that protocols are to communication what algorithms are to
computation. Multiple protocols often describe different aspects of a single communication.
 A group of protocols designed to work together is known as a protocol suite; when implemented in
software they are a protocol stack
Networking hardware
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Networking hardware, also known as network equipment or computer networking devices, are electronic
devices which are required for communication and interaction between devices on a computer network.
Specifically, they mediate data transmission in a computer network.
 Is defined as the hardware and/or software whose primary purpose is to route and control communications
between computers or computer networks. Examples of network devices include but are not limited to,
routers, firewalls and network load balancers.
7 main devices that are used to build a network
 Router, Network cards, Cable, Hub, Bridge, Switch, and Modem.
 Seven main devices used to build a network are as follows
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Network interface card
A network interface controller (NIC, also known as a network interface card, network adapter, LAN
adapter or physical network interface and by similar terms) is a computer hardware component that
connects a computer to a computer network. Early network interface controllers were commonly
implemented on expansion cards that plugged into a computer bus.
The low cost and ubiquity of the Ethernet standard means that most newer computers have a network
interface built into the motherboard, or is contained into a USB-connected dongle.
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Computers use parallel data transmission technology for internal data transfer where multiple bits (binary
digits) are sent simultaneously. However the communication media use serial data transmission, in which a
single data bit is sent at a time. The purpose of the NIC is to convert messages being sent for the media to
be able to handle it and vice versa for the computer to be able to understand it.
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A modulator-demodulator or modem is a computer hardware device that converts data from a digital format
into a format suitable for an analog transmission medium such as telephone or radio. A modem transmits
data by modulating one or more carrier wave signals to encode digital information, while the receiver
demodulates the signal to recreate the original digital information. The goal is to produce a signal that can
be transmitted easily and decoded reliably.
Modems can be used with almost any means of transmitting analog signals, from light-emitting diodes to
radio.
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Modem
Switch
A network switch (also called switching hub, bridging hub, and, by the IEEE, MAC bridge) is networking
hardware that connects devices on a computer network by using packet switching to receive and forward
data to the destination device.
A network switch is a multiport network bridge that uses MAC addresses to forward data at the data link
layer (layer 2) of the OSI model. Some switches can also forward data at the network layer (layer 3) by
additionally incorporating routing functionality.
Such switches are commonly known as layer-3 switches or multilayer switches. Switches for Ethernet are
the most common form of network switch.
Ethernet switch operates at the data link layer of the OSI model and has multiple ports; hence it is used to
connect multiple devices such as computers, servers, printers, IP phones, and many other Ethernet IP
enabled devices.
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SECURITY AND ETHICS
Computer virus
A program software that is designed to harm or damage the normal operations of a computer together with s it's
programs and files and usually causes irreparable damage to the infected computer.
A computer virus is a type of computer program that, when executed, replicates itself by modifying other computer
programs and inserting its own code into those programs. If this replication succeeds, the affected areas are then said
to be "infected" with a computer virus, a metaphor derived from biological viruses. Computer viruses generally
require a host program. The virus writes its own code into the host program.
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How does it affect a computer?
Like the real thing, computer viruses replicate themselves, spreading through your operating system
and network. At the same time, the virus is wreaking havoc: it can damage programs, delete files, and
make devastating changes to your hard drive, all of which can result in reduced performance.
: it can steal data or passwords,
log keystrokes,
spam your email contacts
corrupt files
erase data,
cause permanent damage to the hard disk,
And sometimes can even take over your device control.
How do viruses spread?
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Viruses used to be spread when people shared floppy disks and other portable media, now viruses are
primarily spread through email messages. Unlike worms, viruses often require some sort of user action (e.g.,
opening an email attachment or visiting a malicious web page) to spread.
How does virus spread from one computer to another?
Typically, computer viruses spread through malicious online downloads, infected email attachments, or by
plugging in infected hardware like an external flash drive (USB stick). Computer viruses can spread
through almost any method of file sharing, as long as the virus can avoid detection by antivirus programs.
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Antivirus software
Not opening email attachments coming from unusual people
Update antiviruses regularly
Avoid sharing files using removable media
Avoiding downloading software from insecure sites
Have back up of computer data and programs stored on an external hard drive
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Refers to behavior that is morally or socially acceptable
Ethics are moral obligations and one cannot be taken to court for breaking such.
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Part of computer security that focuses on protecting computer networks and data on the internet.
Methods of preventing viruses
Ethics
Cyber security
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Cyber wellness
 (CW) refers to the positive well-being of Internet users. It involves an understanding of online behavior and
awareness of how to protect oneself in cyberspace. The focus of CW is about helping students to become
responsible digital learners.
Importance of cyber wellness
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Limits amount of time one spends using the computer on the internet
Prevents addiction to online games
Limits websites that one goes to
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Refers to using the internet and online resources
One has to stay safe while using the internet.
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Prioritized to stay safe on the internet
Internet criminals (cyber criminals) can make you visit dangerous sites and then install viruses on your
computer and steal your personal information.
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The address should begin with https and not http
Look for a lock in the address bar
It should have contact information
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Does not have a lock in the address bar and begins with http
Check the spelling if it's correctly spelt
Makes offers that are too good to be true
Offers questionable content such as illegal material or pornography
Lacks legitimacy, no contact information
Request bank details or credit card number to verify identity
Check properties of website link and see if they are genuine.
Cyber use
Characteristics of safe and unsafe sites
Signs of a safe website
Signs of an unsafe website
Handling online content and behavior
 One should take measures from being victims of some other mischievous internet users
Some of the measures
 Avoid using untrusted computers, secondary storage devices such as flash disks, as well as untrusted
websites and networks
 Make sure your computer has to up to date antivirus software since viruses are most common from online
attacks
 Never assume that every email you receive was actually sent by the person listed as the sender
 Avoid click on links in emails unless you requested for them
Bad online content and behavior
a) Inappropriate content
 Exposition to pornographic or illegal material
 Bad beliefs and political views
b) Cyber bullying
 Cyber bullying is bullying - unwanted, repeated, aggressive, negative behavior - that takes place
over digital devices like cell phones, tablets, and computers. Cyber bullying can happen over
email, through texting, on social media, while gaming, on instant messaging, and through photo
sharing.
c) Illegal activity
 Selling of weapons
 Online gambling
 Suicide sites
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Recipes of making bombs and drugs
Online Relationships
Cyber relationships
Internet relationship between two people
Usually they meet online and did never met physically
They know each other through the internet
Copyright issues
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Copyright
The legal right given to an author of original work, to print, distribute, publish perform or film their work,
for a fixed number of years.
It usually expires in 50 years
violating a copy right is illegal
author of original work can take legal action
it is good practice to cite the author of the original work
Copyright infringement
Refers to the use of copyrighted material e.g. book song, film without the permission of the copyright
holder.
Infringement includes using someone’s music to create your own video without getting permission from
the owner
Importance of copyrights
Protects the right of the author or originator of creative work, to control the dissemination and copying of
their work
Unauthorized person are prevented from copying the work
It prevents benefiting from copyrighted material
Plagiarism and piracy
Plagiarism
Refers to the using someone’s work (writing or ideas) without crediting the original author and pretending that it is
yours.
Consequences of plagiarism
a) Destroyed academic reputation
b) Destroyed student reputation
c) Legal charges
Piracy
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Refers to the illegal reproduction of someone’s work
Software piracy refers to0 the illegal, copying and/or distribution of copyrighted software or computer
programs.
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Non viability of software updates
High risk of virus infection
Increased chances that the software will function correctly or will completely fail
Consequences of piracy
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Computer crime
 Refers to all crime committed using the computer
 Is the unauthorized use, access, modification and destruction of hardware, software, data or networked
resources.
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Computer crime can be committed by anyone who uses a computer. However, hackers, disgruntled
employees or customers and an organisation’s competitors usually commit a crime
 Examples of illegal activities
i.
Salami slicing skimming small amounts of money from bank accounts
ii.
Card cloning creating a fake credit card by stealing information
iii.
Denial of service computer activity that results in in legitimate users being denied access from
databases
iv.
Social engineering tricking employees to gain access
v.
Dumpster driving finding private information in garbage cans/rubbish bins
vi.
Spoofing stealing passwords through false login page
 Consequences of computer crime include, but are not limited to, financial loss, increased costs for counter
measures, reduced productivity in companies and job loss.
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Data protection measures
Common data protection includes changing passwords frequently, limiting access to information to key
people only, installing updated antivirus software, and backing up software and dataset files.
Data protection measures
Access control
Authentication
Authorization
Passwords
The ten commandments of computer ethics were developed to guide the ethical of computers for everyone
who uses computers.
Computer ethics
Refer to the moral values that guide individuals as they use computers.
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The ten commandments of computer ethics
Thou shalt not use a computer to harm other people.
Thou shalt not interfere with other peoples computer work
Thou shalt not snoop around in other peoples files
Thou not use a computer to steal
Thou shalt not use a computer to bear false witness
Thou shalt not use or copy software for which you have not paid.
Thou shalt not appropriate other people intellectual output
That shalt think about the social consequences of the program you write
Thou shalt use a computer in ways that show consideration and respect
Privacy
 Privacy refers to an aspect of IT that deals with the ability and power of an individual or organisation to
deter what data in a computer system can be shared with a third party.
 The biggest problem caused by not protecting personal data identity theft.
 The biggest problem caused by not protecting personal data and proof read
 Pin (personal identification number)
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Data integrity
 Refers to the accuracy, reliability and trustworthiness of data throughout its lifecycle
 To maintain integrity, data should not be altered by unauthorized people or programs, neither in transit nor
when stored
It may be compromised by
Viruses, hacking and other computer threats
 Physical damage to st5orage devices
 Transfer errors, including unintended alterations or data, compromise during the transfer from one device
to another
 Human error, either malicious or unintentional
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Data integrity best practices include:
Validation of input data to avoid entering invalid
Error checking (data verification)
Security measures such as control, data encryption and prevention of data loss
Data verification
Data verification checks for accuracy and inconsistency when data is transferred from one source to another.
Data validation methods
a) Double entry entering data twice and compare two copies
b) Proofreading categorising the data entered against the original document
Data validation
 Validation refers to an automatic check that ensures that entered data is meaningful and sensible. In
programming, it is crucial to validate input data. This serves to avoid abnormal or unexpected data from
crashing
 Data validation also ensures that the data sent to connected applications is complete, accurate, secure and
consistent.
 It ensures that data complies with the requirements and quality benchmarks.
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a)
Data validation methods
Techniques that makes sure data is accurate and clean.
They include the following
Range check
 Ensures data falls within a set of range between acceptable lower value and upper limit
 Is the scope of values that data can fall within
E.g. maximum minimum range
b) Type check
 Checks that data expected type entered is correct eg text or numbers
 E.g. date number email
c) Check digit
 An extra number added to a digit which is calculated from other digits
 It ensures the rest of the number is correct
d) Presence check
 Checks if the user entered something
e) Length check
 Check the size of numbers or characters entered meet the expectations
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System security
Processes and techniques used to keep information confidential
It entails the protection of information in transit or stored
Network security measures
They are put forward to fight against hackers, malware and potential threats such as
Fire, theft, accidents, destruction of data, vandalism, hackers
The measures include
Fire wall
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A system that sit at some point of connectivity between the site it protects and the rest of the computer
In most cases it is implemented as an appliance or part of the router
A personal firewall may be implemented on an end user machine.
All incoming and outgoing traffic must pass through it
It controls the network
E.g. a packet filtering router
E.g. soft wares include pfsense, ipfire and smoothwall.
It allows one to specify network traffic to block or filter from reaching your computer
It allows one to let through only the traffic you want to reach.
It accomplishes rules set by the user
It does not protect one from malware
A firewall router is an end point that connects several desktop computers, tablets, laptops and smartphones
on the internet.
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A special category software that monitors activity across a network or a host computer
Watches for suspicious activity and take automated action based on what it sees
It works together with a firewall
Intrusion detection system IDS
Types
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Network IDS
Host based IDS
Signature based IDS
Anomality based IDS
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Proxy is to act on behalf of something
In computer networking, a proxy server is a server application that acts as an intermediary between a client
requesting a resource and the server providing that resource.Instead of connecting directly to a server that
can fulfill a request for a resource, such as a file or web page, the client directs the request to the proxy
server, which evaluates the request and performs the required network transactions.
This serves as a method to simplify or control the complexity of the request, or provide additional benefits
such as load balancing, privacy, or security. Proxies were devised to add structure and encapsulation to
distributed systems. A proxy server thus functions on behalf of the client when requesting service,
potentially masking the true origin of the request to the resource server.
It does not work when connected to virtual private network
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A way of scrambling data or changing data format so that it becomes meaningless to an unidentified person.
The scrambled data is known as cipher text.
Decryption a way of converting cipher text back to it's originally format plain text.
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Proxy server
Encryption
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Additional safeguards to computer network and data
Implement a security plan eg burglar bars
Make data and program backups
Implement technical solutions eg firewalls
Allow access to only authorized person's
Change passwords frequently
Use antivirus software
Use biometrics for access
Cyber crime
Refers to offence or crime performed by or involving use of icts and the internet
Common types of cybercrime
Hacking, spam, cyberbullying and fraud, identity theft, phishing, spoofing and illegal or prohibited online content
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Effects of cybercrime
Upsetting victims
Loss of data
Loss of customers
Loss of revenue
Examples of cyber crime
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Spoofing
Deceiving people into believing an email or website originates from a source it does not
Spoof, spoofs, spoofer, or spoofing may refer to:
Spoofing (finance), a disruptive algorithmic-trading tactic designed to manipulate markets
E-mail spoofing the creation of email messages with a forged sender address.
Spoofing attack A situation in which a person or program successfully identifies as another by falsifying
data...
Sniffing
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Sniffing attack in context of network security corresponds to theft or interception of data by capturing the
network traffic using a packet sniffer (an application aimed at capturing network packets). When data is
transmitted across networks, if the data packets are not encrypted, the data within the network packet can
be read using a sniffer.
Using a sniffer application, an attacker can analyze the network and gain information to eventually cause
the network to crash or to become corrupted, or read the communications happening across the network.
Fraud
 Computer fraud is when a computer is used to gain an unfair advantage over another person.
 The crime of obtaining money or some other benefit by deliberate deception
Common forms
 Identity theft, credit card fraud, scammers and con artist as well as financial swindles
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Hacking
Illegally gaining access to computer systems
Reasons for hacking
Harass other individuals
Show off
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Gain access of computer services without paying
Obtain information to sell
Data backup
 Backup is an additional copy of data that can be used for restoring and recovering purposes.
 It is used when primary copy is lost or corrupted as a result of hardware failure, natural disasters and
malicious damage.
 It is created by copying data to a separate storage device.
 Its purpose is to protect data from loss.
 It should be stored far enough from primary storage
 This is called of site backup
 Automate and streamline recovery process as much as you can.
 Automation lessens the risk of human error.
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Reasons for backup
Disaster recovery
Archival preserving for regulatory compliance. E.g. transaction records, emails, business work products
Recovered in the event of a primary data failure. Primary data failures can be the result of hardware or
software failure, data corruption, or a human-caused event, such as a malicious attack (virus or malware),
or accidental deletion of data.
Backup hardware
Hardware that can be used to store backup copies
Magnetic tape
 Most common type
 Cheap and affordable
 Reasonable performance and standardized formats
 Easy to use
Challenges
 Sequential or linear access
 Cannot be accessed by multiple hosts simultaneously
 Short life span
 Extra care in handling
 Not easy to store
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Magnetic disc
Ease of implementation
Fast access
More reliable
Random access
Multiple host access
Types of backup
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Complete backup
Involves everything the entire piece of work
Useful on relatively small databases
Faster restore time
Slowest back up strategy
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Partial backup
Files changed since last backup
Useful when it's important to have latest version of each file
User defined backup
Back up tools are most commonly found in operating systems.
Cloud backup
Online backup systems Drop box and Google drive
Data loss prevention
 Avoid heat and vibration
 Defragmentate data
 Use of uninterrupted power supply
 Network security
 Physical security
 Strong passwords
 Virus � protection
 Create backup
 Maintain off-site copies of backup
 Use reliable backup media
Data recovery
 Refers to recovery of lost data
 Process of salvaging data from damaged, failed, wrecked or inaccessible primary storage.
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Data loss can be caused by
Natural disasters
Computer virus
Data corruption
Computer crime
human errors
and bad use of information
Data can be recovered from
Deleted data
Overwritten data
Physical damage
Data recovery tools
Software used to recover data from damaged media
E.g. recuva and Pandora
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Disaster recovery
Catastrophic losses of entire systems can happen.
Backup and recovery are essential they should not be considered as disaster prevention
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They are critical components of disaster recovery plan
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Methods, processes and procedures needed to minimize the impact of a disaster upon information and data
required for critical business process.
The objective of a drop is to restore critical business process and it's focus is data recovery.
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Disaster recovery plan
Factors to consider
It should caver everything from usual reasons for data loss
E.g. human failure, smoke, � fire and water damage to not so common incidents like data loss due to
hackers and criminals.
It should be adaptable to any possible hazard
Stack holder should participate for them to be part of it and identify vulnerabilities and capacity.
Conduct frequent updates in addition to hardware and software updates
It should not be unnecessarily long.
Creating a disaster recovery plan
a) Guidelines
b) Conduct a risk assessment
c) Identify data recovery strategies
 Hot � site
Mirrors that run concurrently with your main data center
Fully equipped with hardware and software
 Cold � site
Empty data center
No server or workstation installed
Provides power, cooling and office space which is ready in the event of a significant outage at the
main data center
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Document the DRP
It should be clear and precise
The following should be included
 Steps for recovering from a disaster
 Contact information for software and hardware vendors
 Personnel familiar with the drop
 Location of backups
Test the DRP
See if it works
Identify areas of improvement a
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SYSTEMS ANALSIS AND DESIGN
SYSTEM – A group of elements working together to achieve a common goal.
SYSTEMS ANALYST
-A person who identifies problems of the existing system and recommends the best solution to such a problem.
DUTIES OFTHE SYSTEMS ANALYST
 Identifies the problem of the current system
 Liaises with the system users and determine their requirements.
 Find out facts important to the design of the new system.
 Determine the human and computer procedures that will make-up the system.
 Participate in the process of system implementation.
By performing such duties the system analyst acts as:
i. A consultant – can be called or hired to identify problems in a system.
ii. A support expert- draws together professional expertise concerning computer hardware and software and
their uses in business.
iii. An agent of the change- bring new ideas into the organization
QUALITIES OF A SYSTEM ANALYST
 Must have good written and oral communication skills for all managerial levels of an organization
 Must be able to work as a team
 Must be well educated with at least a degree
 Must be experienced in computers and at top managerial level
 Must have good management skills
 Must be a problem solver and see problems as challenges.
 Must be well disciplined
 Must be able to work under pressure and meet deadlines.
Systems Development Life Cycle
 Systems development life cycle (SDLC) is a set of steps/ stages/phases which are necessary to go through
in developing a new system to solve a problem.
 A conceptual model which includes policies and procedures for developing or altering systems throughout
their life cycles
The generic model
The general or most common way of representing the cycle
A model is a description either text or a diagram of how something is done.
STAGES IN THE SYSTEMS DEVELOPMENT LIFE CYCLE Abbreviation:
(P.F.A.D.I.C.M.)
1.
2.
3.
4.
5.
6.
7.
Problem identification
Planning
Design
Build
Test
deployment
Maintenance
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PROBLEM IDENTIFICATION/ RECOGNITION/DEFINITION and Problem Solving
What is a problem?
The difference between the actual and the desired situation
This is where by the problems of the current system is stated.
These might have been realized by system users or by managers (stakeholders).
The system might be producing wrong results.
We look for things which we do not want of the system
These are referred to as problems of the current system
The problem solving process
The process of defining a problem determining the cause of the problem, identifying and prioritising and
selecting alternatives for a solution
Implementing the solution
It has four problems
1.
Define the problem
 Study current situation to find the problem
 Define the problem so it can be understood by others
2.
Come up with an alternative solution
 Solving a problem is to think and come up with different ways of solving the problem
 They are known as alternative solutions since you can only choose one of the ways in solving the
problem
 NB we don’t choose a solution because we want it. we should have good reasons for supporting it
3.
Evaluate and select an alternative
 Consider an alternative in turn
 Consider issues like cost, feasibility, time to be taken and the organization’s expectations. at the end
you select the alternative that you consider to be the best under the given circumstances
4. Implementing the solution
After choosing a solution we now use it to solve the problem, then you can now start using the SDLC
Data collection techniques
Several techniques can be used but the most common are interview, questionnaire, observation and document
analysis
Document analysis in doing business it is advisable
The process of finding information from the documents kept by the organization
Questionnaires
A document given to users and other stakeholders so that they give information needed.
The person entering that does not include names so that they can say anything anonymously
When the information is gathered together it is used to make decisions.
Interviews
Interview is way of collecting important information from people. They is a interview or and interviewee
Interviews are done face to face which means the interviewee will be talking to the interviewer directly.
Its main advantage I I something is not clear, further questions will be asked to make the point more
understandable some people may be afraid to say out what they think because of fear.
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Observation
It involves the one looking for information and the one doing the work. The one looking for data will go
and watch thing happening.
When you are watching, you write down notes
The methods is good because it makes one to easily understand this because you can get information
direct from where it is unlike when sending someone else describes it for you.
FEASIBILITY STUDY
It involves an evaluation of proposal to determine if it is possible to construct a new system or just modification
of the existing one. It provides directions and reasons for continuing with the development.
Importance of feasibility study
The information obtained from the feasibility study is used to:
 Identify things needed to make the business work
 Point out any business related problems and their solutions
 It provides a strong foundation for developing your business or system.
 It determines early that an idea will not work
 It prevents disappointments, saves time and money
After completing a feasibility study, you produce a feasibility report
Types of feasibility
TECHNICAL FEASIBILITY-
Determines if the organization can obtain software, equipment and personal to develop, install and operate the
system and even to maintain it.
Questions that need answering during technical feasibility are
 Do we have the necessary technology?
 Do we have the necessary expertise in form of the people who will develop and use it?
 Does the company have the technological resources to undertake the project?
 Are the processes and procedures conducive to project success?
 Do the hardware and software available have the ability to support the new system?
ECONOMIC FEASIBILITY
Determining whether the benefits of the new system will outweigh the estimated cost involved in
developing, purchasing, assembling requirements, installing and maintenance of the new system. The
main task of this type of feasibility is to identify and quantify all the benefits that will be derived from the
project and all the expenses in obtaining the system.
Compare the total benefits and total expenses.
That is total benefits minus total expenses.
OPERATIONAL FEASIBILITY
Determines whether the current work practices and procedures are adequate to support the system e.g.
effects on social lives of these affected by the system, can it work well with existing hardware etc.
SOCIAL FEASIBILITY
A measure of the system acceptance by the public if it will meet the norms and values of the society.
ANALYSIS STAGE -The major function is to determine the requirement of the proposed or new system.
It consists of studying the current system followed by defining the new system. Work out a new system
requires, decide what the new system has to do. 4.
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SYSTEM ANALYSIS
System analysis is when the developers of the system develop and documents the properties of a system.
The problems and its solution structure are put in a simpler way to alternatives and are examined and the
most suitable one selected for implementation. After thee analysis phase follows a design phase in which
several types of documents are drawn. The documents are mostly diagrams, for example, flow charts,
decision tables and psuedocodes.
Systems analysis is the process of planning a new system to replace or complement the existing one.
Analyses specifies what the system should do and design states how to achieve that. The examination
should be carried should always be initiated by the people involved in the situation (or who will be
involved in a new situation. The system analysts suggest solutions and do not make business decisions.
Alternative solutions
A solution is an answer to a given problem or a procedure that draws benefits from a business opportunity.
There are many different ways of solving one or the same problem. These possible ways are known as
alternatives. During system analyses , the systems analysts, the system developers need to explore seversl
alternatives and eventually choose and justify one of them.
The chosen one should be the best under given conditions.
Common system alternatives are simply buying a a completely new system to re[place an old one,
modifying the old one in accordance with the new requirements and developing a completely new system
from scratch the old one
Evaluation of alternatives
An evaluation of Alternatives would be by examining the benefits and drawbacks of each.
During the evaluation of alternatives, careful consideration is given to social, economic and ecological
factors that influence the predicted outcome.
It is, advised to use discussion and visual aids to help explain alternatives
There is need of an evaluation criterion
Evaluation is a systematic determination of a subject’s merit, worth and significance, using criteria
governed by a set of standards. An evaluation is a well thought factors that are used to judge the
worthiness of an alternative. Factors to be included in evaluation are effectiveness of the alternative
solution, cost of the resources needed, the expertise needed and the time required.
Data Flow Diagrams (DFDs)
Data flow diagrams (DFDS) models a perspective of the system mostly readily understood by users
They show a flow of information through the system and the activities that process this information.
They provide graphical presentations of the system to the users both specialist and no specialist.
It enables stakeholders to work together during the analyses and specification of requirements
They provide simple and easy sets of constructs to follow.
They show a clear path information should flow through a process or system
It includes
 Data inputs
 Outputs
 Data stores
 Sub processes
They are build using standardized symbols and notations to describe various entries and their
relationships.
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Physical and logical data flow diagrams
Logical data flow diagrams
Focus on what happens in a particular information flow
What information is being transmitted, what entities are receiving that information and what general
processes occur. Processes described are business activities. It does not go into technical aspects of a
process or system
Physical data flow diagrams
Focus on how things happen in information flow
They specify the software, hardware, files and people involved in information flow.
A detailed physical data flow diagram can facilitate the development of the code (program instructions)
needed to implement a data system
Dfd symbols
They are four basic symbols
External entry
Process
Data store
Data flow
Processes are the activities carried out by the system that use and transform information.
They are as rectangles such as order supplies and make payments
The rules for processes
Process names should be an imperative verb specific to the activity in question, followed by a meaningful
description of the object of the activity for example Create Contract or Schedule Jobs, as opposed to using
very general or non-specific verbs, such as Update Customer Details or Process Customer Call.
Processes cannot act as data sources or sinks.
Data flowing in a process should have corresponding output., which is directly linked to it.
Rules for drawing data flows
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Information always flows to or from a process
An exceptional occasion to this rule is a data flow between two external entities
- Data stores may not be directly linked by data flows. A process needs to take place for data to
move from a data store
- Information may not flow directly from a data source to an external entity.
- The sources and sinks of data flows are always represent by external entities
- When something important happens to a data flow, as a result of a process acting on it, the label
of the resulting data-flow should reflect its transformed status
External entities:
These are sources from which information, flows into the system and the recipients of the information
leaving the system
External entities are noted as rectangles, such as “Supplier” or “Customer”.
In other words, external entities are referred to as sources and sinks
Data stores:
This is where information is stored within the system.
They are noted as rectangles with two parts, such as “Supplier Details” and “orders”.
A data store is represented in the data flow diagram by a long rectangle, containing two locations.
D1
Supplier file
The left hand box is the identifier, which is representing a numerical reference prefixed by a letter.
The right hand rectangle is labelled with name of the data store
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Rules for data stores
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One conversion that could be used is to determine the letter identifying a data store by the stores
nature
“M” is used where a manual data store is being depicted.
“D” is used where it is a computer based data store
“T” is used where a temporary data sore is being represented.
Data stores may not act as data stores or sinks.
Drawing data flow diagrams
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Each process should have at least one input and output.
Each data store should have at least one data flow in and one data flow out.
Data stored in a system must go through a process
All process in a DFD goes to another process or a data store.
The benefits of data flow diagrams
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They provide system scope and boundaries since they are indicated in the diagrams
They provide an overall vie of the complete system, as well as a more detailed breakdown and
description of individual activities
Activity diagrams
These consist of activities, states and transitions between activities and states.
Benefits of activity diagrams
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Demonstrate the logic of a computer program
Describe the steps to follow in doing a project
Illustrate a user training programme
Describe how to perform an experiment in science
Basic components of an activity diagram
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Action
Decision node
Control flows
Start node
End node
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SYSTEMS DESIGN
The function is to design a new system that fulfills the requirement of users and of management. Tasks performed
by the analyst in this phase include designing the program structure of the new system in cooperating measures to
guard against any computer crime e.g. password, encryption of sensitive data. - Consider possible solutions which fit
the analysis. -Consider whether new hardware is required. -Consider whether new software is required
INPUT/OUTPUT DESIGN
Input is normally the raw data processed to produce output
During this stage, developers must consider input devices
The quality of the input determines the quality of the output
The following properties are expected
- it should save a specific purpose effectively such as storing, recording and retrieving information
- it ensures proper completion with accuracy.
- It should be easy and straight forward to use
- It should focus on the users consistency, attention and simplicity
Objectives for input design
- Design data entry and input procedures
- Reduce input volume
- Design input data records, data entry screens and user interface screens
- Use validation checks and develop effective input controls
Input methods
It is important to design appropriate data input methods to prevent errors while entering data.
A system should prevent the user from making mistakes by
- Clear form design by leaving enough space for writing legibly
- Clear form design
- Reducing key strokes
- Immediate error feedback
Some of the popular data input methods
- Batch input method
- Online data input method
- Computer readable forms
- Interactive data input.
Output design
This is the most important task of any system
Types of outputs needed identified in this stage and consider the necessary outputs and prototype
report layouts
Objectives of output design
- Should serve the intended purpose and eliminates the production of unwanted outputs
- They should meet end users requirements
- Deliver the appropriate quantity of output
- Form output in an appropriate format and direct it to the right person
- Make output available on time for making decisions
Types of outputs
- Internal outputs stay inside the system to support the system’s users and managers
- External outputs leave the system to trigger actions on the part of their recipients or confirm
actions to their recipients
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Output formats
- Tabular output
- Graphic output
- Narrative output
User interface design
User interface refers to a way in which a computer system presents itself to the user and the way the
user interacts with the computer
General considerations before engaging on designing a use interface
- The problems to be solved – does it include inputting, processing, outputting or storage
- If it accepts input, how are you going to input?
- How are you going to process?
- How are you going to output?
Form design
Important factors
- Who will use them
- Where would they be delivered
- The purpose of the form or report
Objectives of good form design
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To keep the screen simple by giving proper sequence, information and clear captions
To meet the intended purpose by using appropriate forms
To ensure the completion of the form with accuracy
To keep the forms attractive by using icons, inverse video or blinking cursors
To facilitate navigation
Database or file design
The organization of data according to a database model
Database design involves classifying data and identifying interrelationships.
Involves designing tables/files and validation rules.
Data modeling
The first process of database design
Also referred to as conceptual design
It describes the data contained in a database, the relationships between data items, the constrains on
data
The second step is the expression of data items, the relationships and constrains using the concepts
provided by the high-level data model.
The third step is the database design.
They two sub steps
- Database logical design (defines a database in a data model of a specific DBMS)
- Database physical design (defines the internal database storage structure, file organistion or
indexing techniques).
Data is represented using a certain data model.
The data model is a collection of concepts or notations for describing data, data relationships and data
semantics and data constrains
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A relational database organizes data in tables (or relations). A table is made up of rows and columns.
A row is also called a record (or tuple). A column is also called a field (or attribute)
System flow charts
What is a flowchart?
A diagram that shows step by step progression through a procedure or system especially using
connecting lines and a set of conventional symbols.
Basic flow chart symbols
Symbol
Name
Function
START/END
AN OVAL REPRESENTS a start or
end point
Aroow
An arrow is a connector that
shows relationships between the
representative shapes
Input/output
A parallelogram represents input
or output
Processs
A rectangle represents a process
Decision
A diamond indicates a decision
To create a good flowchart you must first familiarise yourself with the most commonly used flow chart
symbols
What is input and output in a flowchart?
These are fundamental blocks of a process used to describe a computer program. The input is provided
by a user. The program will have a code to interprate the input and generate an output.
Algorith design
A procedure is a finite procedure of well defined instructions. They can be mechanically carried out in a
in a specific amount of time. A procedure must break up the problem solution into parts that the
recipient party can understand and execute with minimum effort.the procedure must consists of smaller
steps which the computer can understand.
A solution is a procedure , or method , for transforming the current situation to the desired one .
Points to consider when developing an algorithm
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−
−
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Use suitable identifier names
Are expressed using constraints such as assignment and sequence
Simple algorithms consist of input, process and output
In writing algorithms and their coreesponding programs we use control structures to direct the
course of program execution
DEVELOPMENT AND TESTING
Coding
Coding simply refers to programming
This is the actual development of the system (software) whereby you use a programming language
platform to write computer program.design documents from the previous stages are used
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Testing
A way of finding out and correcting errors
For it to be effective it needs to be planned
A test plan document is prepared
The test plan is a dynamic document
A test plan document that is current at all times determines the success of testing a program
The test plan document
i.
A document that we share with business analysts, project managers, development teams and the
other teams. It helps in improving the level of transparency of the quality assurance team.
ii. It is documented by the quality assurance manager based on the inputs from the quality assurance
team members
iii. It is typically allocated with 1/3 of the time taken for the entire quality assurance engagement. The
other 1/3 is for test designing and the rest for test execution
iv. This plan is not static and is updated on an on-demand basis. The more detailed and comprehensive
the plan is. The more successful will be the testing activity
CONSTRUCTION STAGE The new system has to be created and tested according to the specification set out in the
design. A new system has to be written. -System testing programs and methods ought to be tested and debugged. Tests are carried out.
DOCUMENTATION
Improvements suggest that we develop the system form one level to another level which is usually
better
There is need to document the details of the improvement
The details include the the shortfalls of the original system. How the new system will address those
shortfalls, the methods/techniques used to develop the system.
Reasons for documentation
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Visibility. This refers to the ability of the developers to see the activities what took place at different
stages
User support. Documentation is used to support users of the system during use. When the user is
not sure about carrying out a certain task, he /she will consult the available documentation. In most
cases it is in the form of a user manual.
Team communication. Normally computer systems are developed by a team. The team includes
programmers, system analysts, software engineers, software project managers and so on.
Documentation acts as a means of communication for the team.
Maintenance and evolution. Those who maintain the system are usually different from those who
develop it. The developers should document the process for the maintenance people to have a
reference.
Requirements document
Its is an official statement of what is required of the system developers and what the system should do
and not how it should do it. It acts as a contract between between the developer the customer and the
user.
Structure of the document
 Introduction it gives the purpose of the system
 Current software architecture describes the current state of affairs of the system
 Proposed architecture it describes the high level architecture of the systems under development. It
consists of the following
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 Overview of the system. A brief description of the system, what it does, why it was developed
and development constraints
 Subsystem decomposition. Gives names of subsystems and their associated responsibilities. The
subsystem must interact with the whole system to provide expected services
 Hardware and software assign hardware and software to the identified system
 Data mangement specify the data stored/used by the system
 Access control and security describes the access levels and the methods to be used to
authenticate users in the system.
 Data directory gives the definition of terms used to describe data that is used in the system
Types of documents
Project plan document
An overall plan of developing the software. It gives direction to the development process
Structure of the document
 Introduction it includes the purpose and objectives of the system
 Project organisation describes the different phases of the project from the problem of the
statement to the delivery of the system. It includes time frames and resources to be used
 Risk analysis it identifies the possible risks of developing the system and mitigation measures
 Hardware and software requirements lists all the hardware and software required in developing the
system. It also lists that are already available
 Work breakdown structure. It is the breakdown of the entire project work into smaller manageable
tasks.
 Project schedule. It specifies the duration start times and completion times of each task identified
in the work breakdown structure
 Monitoring and reporting mechanism. It promotes effective communication by letting every team
member to know the communication channels
 User training. Users are the ones who use the system in most cases they don’t have the experience
as the developers. Users should be trained on how to use the system before and during system use.
During training they should know their roles in detail.the following is under user training.
 User training guidelines
Identify appropriate trainees and trainers
Establish measurable objectives
Use appropriate training methods
Select suitable training site
Use understandable training materials
 Training topics
Use of the system
Related computer concepts
Information system concepts
Organisational bussines strategies
System mangement
System installation
How to use the system
SYSTEM IMPLEMENTATION
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Simplified approach to computer science
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-User documentation is prepared. -Users are trained to use the new system. 4 -Technical documentation is prepared
so that the new system can be maintained.
CONVERSION/CHANGE OVER -This involves putting the new computer system into operation that is changing
from the old system to the new one. -It involves file conversion which is the changing of the old data files into the
current format. -Different changeover methods can be used and these include:  PARALLEL RUN This includes or
involves both the old and the new system concurrently until the new system proves to be efficient. It involves
operating the new and old system simultaneously until management is confident that the new system will perform
satisfactory. ADVANTAGES OF PARALLEL RUN -Results for both systems are compared for accuracy and
consistency. -If the new system develop problems, it will be eas
shewag.tm@gmail.com
0779814951
© Tinashe Wagner Makoni
Simplified approach to computer science
Sir Wagner ™
shewag.tm@gmail.com
0779814951
48
© Tinashe Wagner Makoni
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