

- Information Technology: The use of computers to store, retrieve, manipulate and send information.
- Computer: An electronic device that manipulates information, or data and outputs the results.
- Computer Systems: A collection of hardware and software that are designed to receive, process,
manage the instructions/data given by user and return output in the form of human readable
information.
- Hardware: Tangible parts of the computer system.
- Software: Intangible parts of the computer system.

ICT, short for information and communications technology. ICT generally refers to all devices, networking
components, applications and systems that facilitate interaction with the digital world. ICT is more
comprehensive than Information Technology, including more components related to computers and
digital technologies.
- Components include data, Internet access, cloud computing, software, hardware, transactions,
and communications technology. But more importantly, ICT encompasses combinations and
applications of those components.
- ICT has drastically changed how people work, communicate, learn and live, and continues to
revolutionize all parts of the human experience, from computers to robots, and ICT contributes
greatly to our economic development. Some have labeled it the fourth industrial revolution.
- The advancement of ICT capabilities has made the development and delivery of various
technologies cheaper for vendors and their customers, while also providing new market
opportunities for businesses. Advances within ICT have brought a slew of cost savings
opportunities and conveniences, ranging from highly automated cost cutting business processes,
to the big data revolution that leads new insights products and services, to ICT driven
transactions like online shopping, telemedicine and social media.
- ICT is not without its downsides. The digitization of data has led to new levels of crime,
automation tools and robots that can displace workers, and many believe ICT has stifled human
interaction.


A computer System can perform its operations with amazing speed, reliability, accuracy, power and has
communication capabilities.
- SPEED: A computer can process billions of instructions in a single second. E.g. Computers used by
utility companies to produce monthly bills. Without fast and powerful computers this would be
impossible.
- RELIABILITY: Modern computers have a low failure rate, and they produce consistent results.
Computers can work continuously and never go a strike.
- ACCURACY: The computer produces error free results if the data is entered correctly. (GIGO –
Garbage in Garbage out)
- STORAGE: A computer stores large amounts of data in a very small place for later use. Spare
copies or backup can also be stored in case of accidents.
- COMMUNICATION: Communication devices such as modems allows two or more computers to share
stored data and information.

Type of Computer System
Super Computer
Mainframe Computer
Desktop System
Mobile Devices
Embedded Devices




Examples
Cray
IBM zEnterprise
Microcomputers (has a microcontroller)
Personal Computer
Laptops, notebooks, smartphones, tablets, game
consoles, netbooks
Controllers in microwaves, car ignition systems,
answering machines (special purpose systems)



Parts of the computer that can be touched (Tangible)
Hardware components are split in 2 main categories: essential and peripheral.
Essential components are the parts the computer system could not operate without. E.g. Motherboard,
CPU, RAM, ROM and Power supply.
Peripherals are hardware components usually outside the system unit, not NEEDED for the basic
operation of the computer system. E.g. Speaker, keyboard, mouse, scanner, disk drives etc.

- Source Data automation Input Devices: Optical mark reader (OMR), character readers (OCR, MICR),
Magnetic Strip Reader, bar code reader, document scanner, digital camera, biometric systems,
sensors, remote control, sound capture, voice response unit, webcam.
- Key Input Devices: keyboard, specialized keyboards (gaming, disabled)
- Point and Draw Input Devices: mouse, joystick light-pen, touch terminals, Touch Screens (tablets,
point of sale, ATM), pointing devices (trackball, stylus)

Input
Optical Mark reader (OMR):
- leisure (lottery tickets)
- education (multiple choice questions)
Optical character recognition (OCR):
- form processing (automate data entry
from hand-filled applications, surveys,
etc.) or eBook creation from printed
book.
- speech recognition
- assistive technology (text-to-speech)
Microphone:
Touch sensor:
- automated manufacturing
- security systems
Output
Dot-matrix printer:
Inkjet printer:
Laser printer
3D Printer
Thermal (direct)
Plotter
Audio output
documents needed to be printed on thicker
paper.
a document that requires colour printout where
few pages are needed.
documents that must be colour fast (ink wont
smudge) and large volume office documents.
physical objects or architectural models.
small, low cost, single use printouts such as fastfood receipts and transaction receipts.
wallpaper murals/meeting and even signage.
when users have visual impairment, user is
playing an audio or video or when audio is most
appropriate i.e emergency alarms.

- Visual output: Monitors, Printers (laser, inkjet, dot matrix, thermal, plotters, 3D Printers)
- Audible output: speakers, headphones, earphones.




Primary
- Volatile: Data is lost when the power is lost. Temporary Storage.
- Non-Volatile: Data is stored permanently. Data is not lost when the power goes.
Secondary
- Local Devices: Magnetic, optical, Flash memory
- Cloud: Discuss the pros and cons of Cloud vs Local storage

Primary Storage
RAM (Random Access Memory)
Main Memory
Volatile meaning it is lost when power is turned
off
Is used to store the programs and data on
which the computer is currently working.
ROM (Read only Memory)
Consists of nonerasable hardware modules that
contain programs.
Non-volatile meaning contents are not lost when
power is shut off.
Contents are Read Only.
Stores the BIOS (Basic Input Output System)
DRAM - ordinary RAM
PROM - contents can be changed once after
manufacture of the device
SRAM - faster type of RAM
EPROM - The data can be erased and the chip
reprogrammed
EEPROM - enables individual bytes of data to be
erased and reprogrammed
Secondary Storage
Storage Device
Storage Media
Manages the media. Reads and Writes to the The material that stores the content.
media.
Hard Disk (Platters), Floppy Disk, CD, Magnetic
Read/write Head, Flash Drive, Cassette Reader
Tape, Memory sticks
Storage devices
Magnetic devices use
Optical devices use
Flash Memory is
manage the media.
magnets.
lasers.
electronically
programmed or erased.
Floppy Disk
Optical Disk (CD-ROM, Flash Drive
Hard Disk (Zip Disk, Disk CD-R, CD-RW, DVD)
Memory Card
pack, Winchester Disk)


Thumb Drive
Flash Drive
A thumb drive is a solid-state drive that connects A flash drive has a higher performance option than
to the USB port.
the hard disk drive or compact disks with the high
storage capacity ranging from 512 GB to 1 TB.

Both the thumb drive and flash drive are used for transferring and storage for the data.
Thumb drives are pen drives or USB, which are used Flash drives are small integrated chips that can be
to retrieve data.
electronically programmed and erased before they
are used again.
Thumb has the storage of 16, 32, or 64GB versions Flash drives are generally useful or come in use for
with three main USB specifications – USB 1.0, USB digital cameras, USB flash drives, and solid-state
2.0, and USB 3.0 which allows transferring data at drives.
a very quick rate.

Cloud storage: a model in which data is stored on remote servers and can be accessed only via the
Internet or cloud.
Local storage: any physical storage device directly connected (internally or externally) to the computer
system hardware
1. Accessibility:
-
Local storage: user needs physical access to the computer to which the storage is attached.
Cloud storage: can be accessed by the user from any internet-based computer device.
2. Capacity:
-
Local storage: determined by the decision made at the time of purchase; additional storage can be added
when needed.
Cloud storage: more flexible as users can rent as much as they need.
3. Security:
-
Local storage: your responsibility to ensure you have backup in case something goes wrong and also can
be made very secure against an unauthorized person attempting to access your data.
Cloud storage: responsibility of the supplier but even though encrypted before being sent to the internet,
there is a greater chance of an unauthorized person accessing your data.
4. Cost:
-
Local storage: initial purchase cost.
Cloud storage: hire purchase; users pay a monthly fee for 100GB.

Type of Storage
Cloud Storage
Advantages
- Backup
- Remotely update & sync
your files
- Share files easily
- Keep your files encrypted
Local Storage
- Physically on-site, so you
have full control:
- Local storage systems
can be changed easily:
- No Wi-Fi required:
- No hidden fees:
Disadvantages
- You need an internet
connection
- Extra storage space
comes at a cost
- Security & privacy
concerns with some
providers
- Data Security & Safety
- Cost.
- Backup/ Recovery.


The CPU processes the instructions it receives from input devices and gives the required output using
output devices. Processing speed, i.e. how fast the computer can fetch decode execute and store, is
measured in megahertz (MHz) or gigahertz (GHz). A computer word is a group of bits or bytes that may
be manipulated and stored as a unit.
CPU has four basic functions to perform a task:
Machine Cycle
I-Cycle (Instruction): Control Unit fetches from memory the next command. Control Unit decodes the
command into an instruction that the ALU can process.
E-Cycle (Execution): Control Unit retrieves data and commands ALU to execute and ALU complies. Control
Unit stores the result in memory.






There are Four major functions/operations of every
computer system.
-
Input – Accept/Get Data
Process – Manipulate Data
Output – Produce Results
Storage – Keep Data for future use
The above diagram represents the Input Processing Output Storage (IPOS) Cycle of a computer system.
It functions as follows:
1. Data is first put into the computer system via an input device
2. The data which is entered, along with data and instructions from any programs which were
opened, is first placed in Main Memory (also known as Random Access Memory)
3. The Central Processing Unit (CPU) is the 'brain' of the computer and is made of two parts:
- Control Unit - fetches and decodes instructions from main memory and controls the flow
of data and instructions around the computer
- Arithmetic Logic Unit (ALU) - Processes any mathematical or logic (decision making
operations)
4. After processing, the data is converted into information and can be sent to an output device
which will bring information to the user in a human understandable form.
5. A Storage device is used to make a copy or a backup of the information for future use.


Unit
Bit
Byte
Kilobyte
Megabyte
Gigabyte
Terabyte


Abbreviation
b
B
KB
MB
GB
TB
Value
1/8 of a byte
8 bits
1024 bytes
1024 kilobytes
1024 megabytes
1024 gigabytes
Bistable Devices – Device that is either on
or off eg switch, transistor
Files have to be stored as a whole within
the device capacity.
Kilo means 1thousand rep in significant
figures as 103 but because the computer
only has 1 and 0 it is 210 – 1024.



- Memory – GB, MB RAM
- CPU Type/Processor:
Pentium, Celeron (Dual
Core, Quad Core)
- Hard disk capacity –
80GB, 125GB
- CPU Speed – GHz, MHz
- Word Size– 32bit,
64bit
- Display Resolution:
1080p, 1024x768 px
- Gaming Systems vs
Web Browsing Vs
Graphic Designing,
Video Editing,

System software: the category of software used to operate and maintain a computer system
Functions of an operating system:
-
Manage processor resources
Manage memory
Manage storage/input/output devices
Manage files and folders
Maintain a secure computing environment
Establish basic elements for communicating with the user
Kinds of Operating Systems
- Real-time operating systems (RTOS) require no user intervention. They are designed for systems
with a specific purpose and response time (such as robotic machinery).
- A multiuser operating system (network operating system) provides access to a computer system
by more than one user at a time.
- Smartphones have their own specific operating systems, which allow the user to multitask.
- Tablets use operating systems (such as iOS, Android, and Windows 8) that allow interaction with
touch-screen interfaces.

- Gaming consoles use operating systems developed specifically for those particular devices.
- Current operating systems for desktops, laptops, and netbooks have multitasking and networking
capabilities.
Application software: the category of software that performs end user tasks.
1. General Purpose Software: Refers to computer applications that are made for everyone not
designed for a specific business, industry, or department. It is also known as off-the-shelf
software. General-purpose software consists of five main types.
Type
Example
Purpose / Use
Advantages
Disadvantages
Word Processing
Microsoft
Word, Google
Docs & Lotus
Word Pro
Microsoft
Excel, Apple
Numbers,
Google Sheets.
Roblox,
Minecraft,
Netflix &
Disney+
Microsoft
Access, Oracle,
File Maker PRO
Time Saving, Clarity
(fonts and print
options),
Spell/Grammar
checking
Organising data
(rows and columns),
Using Calculations /
Formulae
Relieves Stress
(Allows for relaxation
and relieve anxiety)
Expensive, Userfriendliness (difficult for
novice users)
Spreadsheet
Used to write and
revise documents,
compose the layout
of the text on a
computer.
Used to store,
manipulate and
analyse data in rows
and columns.
Used for leisure and
helps users rest and
relax.
To create, edit and
maintain database
files and records.
Controls Redundancy Data Security (login and
(Saves space and
password protection
time), Easily
available), Concurrent
Manipulated
Access (multiple users
(inserted, modified
can use at the same
or deleted)
time)
Convenience
Technical Problems
(interact from
(machines can
wherever), Saves
malfunction), Can lead to
Money (Reduces
lack of face-to-face
transport cost)
communication
Easier to customise Overwhelming (too many
(full control over
options for transitions
appearance),
and animations can
Entertainment
Database
Communication
Zoom, Skype,
Microsoft
Teams
Provide remote
access to systems
and exchange files
and messages.
Presentations
Microsoft
PowerPoint,
Creates sequences
of words / pictures
User - friendliness
(difficult for novice
users), Lack of Security
Addictive (cause
negligence of important
tasks.

Prezi, Google
Slides
Graphics
Adobe
Photoshop,
Microsoft
Paint, Inkscape
and supports a public
presentation.
Efficient
frustrate, replaces
organization and
planning and
planning (many
preparations (can be
features to enhance)
seen as only a prop)
Used to create
Design (extremely
Complexity (Not very
user-friendly
and has a
digital images, ability
useful in style and
lot of advanced tools
to create, edit and
creating)
and
features that would
save images.
be foreign to novice
users)
2. Specialized Software: This is software that is specially designed for an individual or company's
specific needs/discipline. It does not have much use beyond those tasks, so it can be quite
expensive. Examples include
- Airline Reservation System (Used by airlines)
- Peach Tree (Used by accountants)
- CAD (Used by architects)
- Expert System –This is a system used by doctors that ask patients a series of questions
and make a diagnosis.
3. Custom Written Software: This type of software is often called tailor-made or bespoke which is
created specifically for a user or an organization by a programmer. It is designed to fit the specific
needs of the user or organization. This enables a company to get its software exactly how they
want it.
- E.g. a shoe store hiring a programmer to create a point-of-sale program to handle their
business needs.
4. Integrated Software: This is a set of useful applications that are bundled together or sold
together as one package. E.g.
- Microsoft Office
- AppleWorks
- Lotus SmartSuite
- Corel WordPerfect Office
- WPS Office

5. Customised-General Purpose: This type of software is general-purpose software that has been
modified by a programmer to fit the needs of a user or organization. For example:
- Installing adobe reader plugin/addons to read pdf files in word.
- Installing an addon in google chrome.
Utility software:
- Backup: creates a spare copy of data and program files to protect them in case of an emergency
- Disk defragmenter: organises files on the disk drive so that the computer can access files faster
- Disk error checker: examines files, folders and the platter surfaces of the specified hard disk
drive and repairs any faults found
- Disk clean up: clears disk of any unnecessary files
- Antivirus: checks/removes viruses that may infect the system

A User Interface is the part of the computer (hardware or software) that interacts with the user. The
user interface is sometimes more formally called the Human Computer Interface (HCI). The user-friendlier
an HCI, the easier it is for a user to use. We will now take a look at the different types of HCI as it relates
to software.
There are three types of User Interfaces:
- Command Driven User Interface
- Menu Driven User Interface
- Graphical User Interface
A. Command Driven User Interface:
This is the oldest type of user interface and perhaps the least user friendly. It involves the use
of commands that are typed in by the user to instruct the computer as to what task to perform.
The commands are typed in at the command line, which is usually to the right of the C prompt. A
command driven user interface requires the user to be familiar with the commands that are
available, what they do and how they should be used. It is very quick if the user knows all or most
of the very important commands. It is therefore not suited for novice users, as they will need to
learn the commands before being able to be verse in the use of the program.

Advantages of a Command Driven User Interface
*
*
User can quickly enter commands if they are familiar with them
Commands are executed faster by the processor.
Disadvantages of a Command Driven User Interface
*
*
*
Requires knowing the commands to work quickly and efficiently
Not suitable for novice users
Limited choice in input devices. Input device is usually limited to a keyboard.
B. Menu Driven User Interface:
Allows the user to select an action to be initiated from a list of options that are displayed. There
are different types of menus namely Pull-down and Pop-up menus. A Pull-down menu is one where
the items in the list to be selected drops down when the menu is selected. Simply put another
menu is displayed below the one selected. A Pop-up menu is one where the items in the list "popsup" when the menu is selected. In other words, another menu is displayed above the one selected.
Advantages of a Menu Driven Interface
*
*
Commands can be entered from a variety of input devices
User does not need to remember commands as they are selected from a list of options.
Disadvantages of a Menu Driven Interface
*
*
To execute a command the user maybe required to go through many steps.
Though commands do not have to be memorised users must know the menu under which
the desired command is located in order to move quickly and efficiently.
C. Graphical User Interface:
Graphical User Interface GUIS GUI pronounced 'gooey' is a HCI that uses a graphical display with a
combination of menus, buttons, icons and other graphical images to give commands. A GUI is
arguably the most user-friendly user interface. It gives the user complete control over what
he/she is doing. It is easier for a person to remember a graphical object and what it represents
than to remember some keyword. Often the objects used symbolize exactly what they do. An
Icon is a graphical object used to represent commonly used features.

Advantages of a GUI
*
*
*
The use of icons that is representative of the task being done results in less errors in the
entering of commands
Best suited for novice users
Reduce typing
Disadvantages of a GUI
*
*
Uses a lot of processor resources
Slowest interface due to the processing of colours, images, text, etc.

- Data is raw facts and figures while information is processed data
- Information processing is the collecting, storing, interpretation, and retrieval of data. E.g: The use
of an electric kettle (once the water boils at the desired temperature, it will activate to turn off
the kettle)

General tips to keep in mind
There are many different things that could cause a problem with your computer. No matter what's
causing the issue, troubleshooting will always be a process of trial and error—in some cases, you may
need to use several different approaches before you can find a solution; other problems may be easy to
fix.
General Troubleshooting Tips
1. Write down your steps: Once you start troubleshooting, you may want to write down each step
you take. This way, you'll be able to remember exactly what you've done and can avoid repeating
the same mistakes. If you end up asking other people for help, it will be much easier if they know
exactly what you've tried already.
2. Take notes about error messages: If your computer gives you an error message, be sure to write
down as much information as possible. You may be able to use this information later to find out
if other people are having the same error.
3. Always check the cables: If you're having trouble with a specific piece of computer hardware,
such as your monitor or keyboard, an easy first step is to check all related cables to make sure
they're properly connected.
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4. Restart the computer: When all else fails, restarting the computer is a good thing to try. This can
solve a lot of basic issues you may experience with your computer.
Using the Process of Elimination
If you're having an issue with your computer, you may be able to find out what's wrong using the process
of elimination. This means you'll make a list of things that could be causing the problem and then test
them out one by one to eliminate them. Once you've identified the source of your computer issue, it will
be easier to find a solution.
Scenario #1: Printer Problem
Let's say you're trying to print out invitations for a birthday party, but the printer won't print. You have
some ideas about what could be causing this, so you go through them one by one to see if you can
eliminate any possible causes.
Solutions #1: Printer Problem
* First, you check the printer to see that it's turned on and plugged in to the surge protector. It is, so
that's not the issue. Next, you check to make sure the printer's ink cartridge still has ink and that there
is paper loaded in the paper tray. Things look good in both cases, so you know the issue has nothing to
do with ink or paper.
* Now you want to make sure the printer and computer are communicating correctly. If you recently
downloaded an update to your operating system, it might interfere with the printer. But you know there
haven't been any recent updates and the printer was working yesterday, so you'll have to look elsewhere.
* You check the printer's USB cord and find that it's not plugged in. You must have unplugged it
accidentally when you plugged something else into the computer earlier. Once you plug in the USB cord,
the printer starts working again. It looks like this printer issue is solved!

Scenario #2: Power button problem
Power button will not start computer.
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Solutions #2: Power button problem
* If your computer does not start, begin by checking the power cord to confirm that it is plugged
securely into the back of the computer case and the power outlet.
* If it is plugged into an outlet, make sure it is a working outlet. To check your outlet, you can plug in
another electrical device, such as a lamp.
* If the computer is plugged in to a surge protector, verify that it is turned on. You may have to reset
the surge protector by turning it off and then back on. You can also plug a lamp or other device into the
surge protector to verify that it's working correctly.
* If you are using a laptop, the battery may not be charged. Plug the AC adapter into the wall, then try
to turn on the laptop. If it still doesn't start up, you may need to wait a few minutes and try again.

Scenario #3: An application is running slowly
* Close and reopen the application.
* Update the application. To do this, click the Help menu and look for an option to check for Updates. If
you don't find this option, another idea is to run an online search for application updates.
Scenario #4: An application is frozen
Sometimes an application may become stuck, or frozen. When this happens, you won't be able to close
the window or click any buttons within the application.
Solution #4: An application is frozen
* Force quit the application. On a PC, you can press (and hold) Ctrl+Alt+Delete (the Control, Alt, and
Delete keys) on your keyboard to open the Task Manager. On a Mac, press and hold
Command+Option+Esc. You can then select the unresponsive application and click End task (or Force Quit
on a Mac) to close it.
* Restart the computer. If you are unable to force quit an application, restarting your computer will
close all open apps.
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Scenario #5:
All programs on the computer run slowly
Solutions #5:
* Run a virus scanner. You may have malware running in the background that is slowing things down.
* Your computer may be running out of hard drive space. Try deleting any files or programs you don't
need.
* If you're using a PC, you can run Disk Defragmenter.
Scenario #6: The computer is frozen
Sometimes your computer may become completely unresponsive, or frozen. When this happens, you won't
be able to click anywhere on the screen, open or close applications, or access shut-down options.
Solutions #6: The computer is frozen
* (Windows only): Restart Windows Explorer. To do this, press and hold Ctrl+Alt+Delete on your keyboard
to open the Task Manager. Next, locate and select Windows Explorer from the Processes tab and click
Restart. You may need to click More Details at the bottom of the window to see the Processes tab.
* (Mac only): Restart Finder. To do this, press and hold Command+Option+Esc on your keyboard to open
the Force Quit Applications dialog box. Next, locate and select Finder, then click Relaunch.
* Press and hold the Power button. The Power button is usually located on the front or side of the
computer, typically indicated by the power symbol. Press and hold the Power button for 5 to 10 seconds
to force the computer to shut down.
* If the computer still won't shut down, you can unplug the power cable from the electrical outlet. If
you're using a laptop, you may be able to remove the battery to force the computer to turn off. Note:
This solution should be your last resort after trying the other suggestions above.
* Press and hold the Power button. The Power button is usually located on the front or side of the
computer, typically indicated by the power symbol. Press and hold the Power button for 5 to 10 seconds
to force the computer to shut down.
* If the computer still won't shut down, you can unplug the power cable from the electrical outlet. If
you're using a laptop, you may be able to remove the battery to force the computer to turn off. Note:
This solution should be your last resort after trying the other suggestions above.
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Scenario #7
The mouse or keyboard has stopped working.
Solutions #7
* If you're using a wired mouse or keyboard, make sure it's correctly plugged into the computer.
* If you're using a wireless mouse or keyboard, make sure it's turned on and that its batteries are
charged.
Scenario #8
The sound isn't working
Solutions #8
* Check the volume level. Click the audio button in the top-right or bottom-right corner of the screen
to make sure the sound is turned on and that the volume is up.
* Check the audio player controls. Many audio and video players will have their own separate audio
controls. Make sure the sound is turned on and that the volume is turned up in the player.
* Check the cables. Make sure external speakers are plugged in, turned on, and connected to the correct
audio port or a USB port. If your computer has color-coded ports, the audio output port will usually be
green.
* Connect headphones to the computer to find out if you can hear sound through the headphones.
* Check the cables. Make sure external speakers are plugged in, turned on, and connected to the correct
audio port or a USB port. If your computer has color-coded ports, the audio output port will usually be
green.
* Connect headphones to the computer to find out if you can hear sound through the headphones.
Scenario #9
The screen is blank
Solutions #9
* The computer may be in Sleep mode. Click the mouse or press any key on the keyboard to wake it.
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* Make sure the monitor is plugged in and turned on.
* Make sure the computer is plugged in and turned on.
* If you're using a desktop, make sure the monitor cable is properly connected to the computer tower
and the monitor.
* Check the brightness control, located on your monitor or your keyboard, and make sure it is not set
too low.
Solving more difficult problems
If you still haven't found a solution to your problem, you may need to ask someone else for help. As an
easy starting point, search the Web. It's possible that other users have had similar problems, and solutions
to these problems are often posted online. Also, if you have a friend or family member who knows a lot
about computers, they may be able to help you.
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A spreadsheet is a computer program that organizes data into rows and columns. Each row and column
can be manipulated with formulas, commands, and formats. This tool is especially useful for accountants,
financial analysts, and business people to analyze business performance numbers and results.
Some Spreadsheet package includes:
-
Microsoft Excel
Lotus 123
Open Office
Google Sheet
Numbers (IPad & IPhone)
Purpose of a spreadsheet:
-
Storing & calculating accounting information.
Calculating financial information.
Creating Budget.
Sorting and storing data.
Creating Graphs and Charts.
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Terms Associated with Spreadsheet
- Workbook - is a spreadsheet file. It contains at least one worksheet, and may contain several
worksheets.
- Worksheet - is a single page in a spreadsheet file.
- Columns - run from top to bottom of the window and their position is designated by a letter.
- Rows - run from left to right across the window and their position is designated by a number.
- Cell - is the intersection of a column and a row. Example cell G10 is the intersection of column G
and row 10.
- Cell address - identifies a single cell in a worksheet. It is given the format B23, where the letter
indicates the column and the number indicates the row.
- Range - a group or block of cells that form a rectangle in the worksheet. A range is referenced
by indicating the upper left cell and the lower right cell, placing a colon between the two cells.
For example, the range C2:D4.
- Labels - are non-numeric data that will not be used in calculations, e.g. a person’s name.
- Values - are data used for calculations, e.g. an employee’s salary
- Formulae - can be entered in a cell to perform calculations on values in other cells. A formula
always begins with =. For example, =B1+B2,
- Functions - are shortcuts that is used in place of entering lengthy and complicated formulae.
Example we could enter the function =max(B1:B2) to find which cell has the maximum value.
Function
Sum
Average
Max
Min
If
Count
Counta
Definition and Format
The SUM function is used to add the values in a range of cells. For example, =SUM(A1:F1)
The AVERAGE function is used to find the average for a range of cells. For example,
=AVERAGE(A1:F1)
The MAX function can be used to find the maximum (highest) value in a range of cells.
Example, =MAX(B2:B5)
The MIN function can be used to find the minimum (lowest) value in a range of cells.
Example, =MIN(B2:B5)
IF (Logical test, Value if True, Value if False) Used to give a cell a result based on some
condition existing
The COUNT function can be used to count the number of cells in a range that contains
numeric or date values. Example, =COUNT(B2:B5)
The COUNTA function can be used to count the number of cells in a range that contains
text or numeric values. =COUNTA(B2:B5)
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Countif
Vlookup
an Excel function to count cells in a range that meet a single condition. COUNTIF can be
used to count cells that contain dates, numbers, and text. The criteria used in COUNTIF
supports logical operators (>,<,<>,=). Example =COUNTIF(C3:C7,"boy") or
=COUNTIF(C4:C8,">50")
stands for ‘Vertical Lookup’. It is a function that makes Excel search for a certain value
in a column (the so called ‘table array’), in order to return a value from a different column
in the same row. Syntax: =VLOOKUP ([value], [range], [column number], [false or true])
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Information Processing refers to the collecting, storing, interpretation and retrieving of data. Depending
on the data inputted, a particular output is provided. Many of the devices we used today involve the
processing and interpretation of a particular input (data). Take, for example, an electric kettle, where
once the water boiled at a desired temperature, the sensor will activate a switch to have the kettle
turn off. The used of an ATM is also included where, based on your input, you can either make a deposit,
do a withdrawal, top up your phone with credit, etc.
- Data- raw unprocessed facts and figures that a computer processes by following a set of
instructions call a program.
- Information- process data which is meaningful and useful.
Sources of Data and Information
- People
- Places
- Things
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Source documents- When an employee takes a document and enters the data into computer system,
the document is referred to as a source document. Once the data has been entered it should be filed
away safely, and not thrown away. That is because data may have to be checked again.
Human-readable documents- Many forms are filled in by hand and the employee has to read them before
entering the data on a keyboard. These are called human-readable documents. Acquiring data by this
means can prove to be challenging for several reasons. The person filing the document may
misunderstand the questions asked, his or her handwriting is difficult to read and understand, and there
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is also the possibility of him or her leaving out some sections of the document. To alleviate this problem
by instructing an individual to write using capital letters, as well as have a series of boxes place on the
document to allow separation of letters and numbers. Such documents can be used in banks for making
cash deposits, which one has to write the account number in subsequent boxes, or when one fills out the
form to apply for you passport.
Machine-readable- are one solution to the problem of unclear handwriting. Instead of filing out the data
by hand, the form is marked by some means. A particular scanner or reader is normally used to scan the
document and identify the marks made by the human. The drawback is that only selected type of data
can be processed by such machines. For example, multiple choice papers, you would have shaded for an
e-learning examination or mock examination, a point-of-sale terminal, when a particular item is swiped
by a barcode reader, the barcodes printed on the product are examples of machine-readable documents.
Turnaround document- A turnaround document is a machine-readable document that has some
information printed on it by a computer but has some information printed on it by a human. It is then fed
back into a computer to transfer this newly added information. These documents serve two purposes.
They are used to: Verify the accuracy and completeness of information that has already been entered.
Update information already entered with additional data. Example: multiple choice sheets, utility bill,
prescription form where you are entitled to sign to be returned to the respective entities,
Soft Copy: This refers to the output or information displayed on a screen (visually) or in an audio or voice
form. Soft copies can be sent via email or over a network connection, which makes them a more efficient
and cost-effective option than using hard copies for communications.
Hard Copy: This refers to the output printed onto paper. This is also called permanent output. Hard copies
are used by individuals for a number of reasons. In some cases, there is the idea that hard copies can act
as a back-up for digital documents that may be lost or destroyed. In other cases, hard copies are simply
easier to keep track of, easier to transport, or easier to distribute. There are also instances where hard
copies are used as schemas, or templates, that are marked with pencil or pen.
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The Internet is an amazing and almost limitless source of information, but it can also present problems
and challenges. How do you know the websites you're using for research are quality sites? The following
are criteria to follow.
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Currency: The timeliness of the information.
-
When was the information published or posted?
Has the information been revised or updated?
Does your topic require current information, or will older sources work as well?
Are the links functional?
Relevance: The importance of the information for your needs.
-
Does the information relate to your topic or answer your question?
Who is the intended audience?
Is the information at an appropriate level (i.e. not too elementary or advanced for your needs)?
Have you looked at a variety of sources before determining this is one you will use?
Would you be comfortable citing this source in your research paper?
Bias: Use the point-of-view of more than one author.
-
What kind of information is included in the website?
Based on your other research, is it accurate? ...complete?
Is the content primarily fact, or opinion?
Is the information balanced, or biased?
Does the author provide references for quotations and data?
If there are links, do they work?
Authenticity: The source of the information is legitimate or real.
-

Who is the author/publisher/source/sponsor?
What are the author’s credentials or organizational affiliations?
Is the author qualified to write on the topic?
Is there contact information, such as a publisher or email address?
Does the URL reveal anything about the author or source? examples: .com .edu .gov .org .net
Where does the information come from?
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
Data validation- Data validation checks are carried out by a computer system when data is entered, to
identify data that cannot be corrected.
Methods of Data Validation:
You may have entered your personal details into a web-based form online. If you leave out some data
that ought to be included it will give a message and ask you to enter it. Similarly, if you type in a password
incorrectly it will test you to try again. These are examples of Data Validation.
1. Range Checks- This check whether numerical data is within expected limits. For example: if you
are asked to enter someone’s age, the number should be between 0 to 110.
2. Data type checks- This check whether the data is of the correct type, such as number, date,
text. For example: Phone numbers are numerical, so data type check would notice if a letter was
included.
3. Inconsistency checks (also known as consistency checks) – This method checks one piece of
data against another. For example: the data may include both gender (M or F) and title (Mr., Mrs.,
Miss). If someone has entered M and Mrs., then the data items are inconsistent.
4. Presence check- Presence checks are used to check that data has been entered into a field and
has not been left blank.
5. Length Check- Length checks are used to check that the number of characters entered in a field
does not exceed the amount allocated for the field or is not less than specified.
6. Format check-Format checks are used to check that the data is entered in the format specified
by the software. For example: A car registration number should consist of one to three letters
followed by one to four numbers.
7. Reasonableness Checks- A test to determine whether a value conforms to specified criteria. A
reasonableness checks on a data is really common-sense check. Does data fall within an accepted
range or consist of accepted value. Does it even make sense? There is no 14th month, humans
don’t live past 120 years, it’s not common to hire an employee who is 10 years old, and no month
has more than 31 days.
Data verification- data verification takes place when a person checks that data has been correctly keyed
into a computer system.
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Methods of Data Verification
- Double entry verification- Double entry is a common method of data verification in which the
data is keyed in a second time, and the first entry is checked against the second.
- Proofreading- Proofreading means examining your text carefully to find and correct errors
(Detects typographical errors and transpositional errors). Examples of Errors
- Correct Sentence-I went down the street and saw my friends playing cricket.
- Typographical errors- I sent down the street and saw my friends playing cricket.
- Transpositional errors- I went down the street and was my friends playing cricket.

The OS allows you to organize the contents of your computer in a hierarchical structure of directories
that includes files, folders, libraries, and drives.
Types of Files: Depending on the data that is stored they file types will vary.
- Image Files – colour values are stored in a particular position know as a pixel. A group of
pixels create an image.
- Document Files – these files contain text, numeric and image data. These documents are
usually formatted in a particular order that is a set standard.
- Video Files – these files contain motion pictures.
- Presentation Files – similar to document files, these files contain text, numeric and image
data, but it is formatted in a specific way to be easily projected.
- Audio Files – these files contain sound waves/recordings
- Program files – these files contain instruction that the computer will understand how to
execute (code).
File Extensions
A file name is comprised to 2 parts > FILENAME.EXTENSION
The file name is whatever the user saves the file as.
The extension determines how the computer interprets the file and what application manipulate the
file.
-
Image –jpg, jpeg, gif, svg, png, tiff
Document – doc, docx, pdf, txt, xls, xlsx, htm, html, xml, dat
Compressed – tar, zip, rar
Video – mp4, avi, mov, flv, avchd
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- Presentation – key(apple), odp, ppt, pptx
- Audio –m4a, mp3, wav
- Program – exe, bat, apk, app, sys
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
File organization refers to the way data is stored in a file. File organization is very important because it
determines the methods of access, efficiency, flexibility and storage devices to use.
There are four methods of organizing files on a storage media:
- Direct access file organization- Direct access also called a random-access file, allows the
computer to go directly to a specific piece of data on the storage media without having the
access any other data. (For example: Hard disk, Floppy disk)
- Sequential file organization- Sequential file organization describes a file that is sorted using data
in one of the fields. Hence Sequential file are sorted in some way. With sequential access data is
retrieved in the order in which it was stored. Magnetic tape drives use this type of method to
retrieve data stored on the data tapes. (For example: magnetic tape)
- Index - sequential file organization- Index-sequential file organization uses index file to speed up
searches on a sequential file. To think of Index-sequential file organization, A dictionary with the
letters written on it would be a real-life example of how Index-sequential file organization words.
Where the letters would be and index to quickly find the beginning of the word that you are
looking for and afterwards words would be searched for sequentially until the world is found;
similar to how Index-sequential file organization works in computing.
- Serial file organization- Serial files are stored as each record is received it is stored in the next
available storage position. In general, it is only used on a serial medium such as magnetic tape.
This type of file organization means that the records are in no particular order and therefore to
retrieve a single record the whole file needs to be read from beginning to end.

Archiving- this is the process of removing files that are no longer actively used to separate storage
device for long term retention. Archived file is still important to the organization and may be needed for
future reference or must be retained for regulatory compliance. Files that are archived may be accessed
in a serial manner or directly depending on the file organization methods used.
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Payroll file- The employee payroll file is the source for anything that has to do with an employee’s pay
check. It includes information about employee’s gross salary, deductions, net pay etc. The main reason
to create a payroll file, which is likely to be stored in a sequential manner, is to limit access to the rest
of confidential information that is located on the personnel file.
Real time Systems- This is a software system where the correct functioning of the system depends on
the results produced by the system and the time at which these results are produced. This system is
time critical and thus, real time system must respond within a specific time period. For example, real time
system would be suited for Air traffic control System, Network Multimedia System and Command Control
System.
*Something someone said we should know*
- Master file: a permanent file, periodically updated, that serves as an authoritative source of data.
- Transaction file: used to hold data during transaction processing