1. Computer/IT SS 3

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Theme 1       Information and Communications Technology       

  1. Networking
  2. Introduction to the World Wide Web (WWW)
  3. Cables & Connectors

Theme 2       Computer Applications  

  1. Database
  2. Graphics (Introduction to CorelDraw)

Theme 3       Problems – Solving Skills

  1. BASIC programming III (One dimentional array)
  2. High-Level Languages (H.L.L.)

Theme 4       Coding Systems in Computer    

  1. Overview of Number BASES
  2. Data Representation

Theme 5       Computer Ethics   

  1. Security and Ethics




Table of Contents

Theme 1  Information and Communications Technology

  1. Computer Network

Computer networks are interconnected systems that allow computers and other devices to communicate, share resources, and exchange information. These networks come in various types, each suited for specific purposes and scales. Here are some common types of computer networks:


Types/Categories of Computer Networks

Computer networks are classified according to organizational structure, usage patterns, and operational coverage. These encompass:


  1. Local Area Network (LAN)

A LAN is a network that spans a relatively small geographic area, such as a single building, office, or campus. LANs are typically used to connect devices like computers, printers, and servers. Ethernet cables or wireless connections are commonly used to establish LANs.


  1. Wide Area Network (WAN)

WANs cover larger geographical areas, often connecting LANs across cities, countries, or continents. The internet is the most well-known example of a WAN. WANs use routers, switches, and communication lines like leased lines, fiber optics, and satellite links to connect distant locations.


  1. Metropolitan Area Network (MAN)

MANs are larger than LANs but smaller than WANs, covering a city or a metropolitan area. They are often used by organizations that need to connect multiple offices within a city.


  1. Campus Area Network (CAN)

CANs are networks that cover a campus or a large university. They provide connectivity between various departments and buildings on the campus.


  1. Personal Area Network (PAN)

A PAN is the smallest type of network, typically connecting devices within a short range, like personal devices (e.g., smartphones, laptops, and tablets) using technologies such as Bluetooth or infrared.


  1. Wireless Local Area Network (WLAN)

A WLAN is a type of LAN that uses wireless technology (such as Wi-Fi) to connect devices within a specific area, eliminating the need for physical cables.


  1. Virtual Private Network (VPN)

A VPN is a network that creates a secure and encrypted connection over a public network (usually the internet). It allows remote users to access a private network as if they were directly connected to it, ensuring data privacy and security.


  1. Intranet

 An intranet is a private network that functions similarly to the internet but is restricted to a specific organization. It enables employees to share resources, collaborate, and communicate within the organization.


  1. Extranet

An extranet is an extension of an intranet that allows authorized external users, such as partners, suppliers, and clients, to access certain parts of an organization’s internal network.


  1. Client-Server Network

In this network model, one or more powerful servers provide services and resources to client devices. Clients request and use services, while servers manage and deliver those services.


  1. Peer-to-Peer Network (P2P)

In a P2P network, devices, or nodes, communicate directly with one another without relying on a central server. P2P networks are often used for sharing files and resources between users.


  1. Cloud Network

Cloud networks leverage cloud computing services to deliver resources and services over the internet. Users can access applications and store data remotely, without the need for local infrastructure.


  1. Industrial Control System (ICS) Network

These networks are used in industrial environments to connect and control machinery, equipment, and processes. They are essential in sectors such as manufacturing, energy, and transportation.


  1. Sensor Networks

Sensor networks consist of interconnected sensors that gather and transmit data from the environment. They are used in applications like environmental monitoring, healthcare, and home automation.


  1. Home Area Network (HAN)

HANs are designed to connect devices within a household. Smart devices like thermostats, lights, and appliances can be part of a HAN, allowing remote control and automation.


  1. Storage Area Network (SAN)

A SAN is a high-speed network dedicated to connecting storage devices, such as disk arrays and tape libraries, to servers. SANs are commonly used to enhance storage capacity and performance in data centers.


  1. Overlay Network

An overlay network is created on top of an existing network infrastructure to provide additional functionality or features. Virtual private networks (VPNs) and content delivery networks (CDNs) are examples of overlay networks.


  1. Global Area Network (GAN)

GANs connect multiple networks across the world, often using satellite and terrestrial wireless communication. They are used for global communication and coordination in sectors like military and international organizations.


  1. Enterprise Private Network

This type of network is established within an organization and is designed to facilitate secure communication and data sharing among its various branches, departments, and offices.


  1. Cellular Network

Cellular networks provide wireless communication for mobile devices like smartphones and tablets. These networks use a system of cell towers to provide coverage and allow users to access voice and data services.


  1. Satellite Network

Satellite networks use communication satellites to transmit signals between ground stations and satellite dishes. They are used for various purposes, including television broadcasting, internet access, and global positioning systems (GPS).


  1. Municipal Area Network (MANet)

A MANet is a network that covers a specific area within a city or municipality, often providing free public Wi-Fi access to residents and visitors.


  1. Hybrid Network

A hybrid network combines different types of networks, such as LANs, WANs, and cloud services, to create a unified and versatile communication infrastructure.


  1. Mesh Network

A mesh network consists of interconnected nodes, where each node can communicate with several other nodes directly. Mesh networks are highly resilient and self-healing, making them suitable for scenarios where network reliability is crucial.


  1. Blockchain Network

Blockchain networks are decentralized and distributed ledgers that use cryptographic techniques to secure transactions and information. They have applications in secure data sharing, cryptocurrencies, and smart contracts.

These are examples of the many types of computer networks that exist. The choice of network type depends on factors like the geographical scope, connectivity requirements, security needs, and the purpose of the network.


Workstation/Client: Each computer within a network is commonly referred to as a workstation or client. Clients are the machines capable of accessing shared network resources made available by a server.

Server: A server offers shared resources and data across a network. It typically entails a high-performance microcomputer with multiple drives, often possessing substantial storage capacity and potentially a few CD-ROM drives. Servers permit all microcomputers to access an external network through the network communication system.

Media: The interconnection of computers relies on hardware components such as cables (UTP, STP, coaxial, and fiber optics).

User: An individual who employs a client to access network resources.

Resources: These encompass files, printers, modems, or other items employable by network users. Resources can manifest as hardware or software entities.

Protocol: Protocols denote prescribed rules employed for communication. They represent the language computers employ to interact within a network, examples being TCP/IP and AppleTalk.


Network Topology:

Topology characterizes the physical arrangement of computers within a network. Networks can be structured in diverse ways, such as:

Types of Network Topology:

  1. Star Topology
  2. Bus Topology
  3. Ring Topology
  4. Hierarchical Topology


Star Network:

In this configuration, multiple small computers link to a central resource, often termed a host computer or file server. The star arrangement is common for connecting microcomputers to a mainframe, establishing a time-sharing system. This design offers heightened security as communication between workstations transpires through the central node (servers).

Advantages of Star Topology:

  1. High reliability; failure of a node or cable does not disrupt other nodes.
  2. Easy addition of new nodes without major impact on network performance.
  3. Performance relies on the central hub’s capacity, with minimal impact from added nodes.
  4. Centralized management simplifies network monitoring.
  5. Simple and cost-effective installation and upgrading to a switch.

Disadvantages of Star Topology:

  1. Network failure if the server or server link falters.
  2. Added devices (hubs/switches) increase overall costs.
  3. Node addition contingent on central device capacity.
  4. Reconfiguration, fault isolation, and device installation can be complex.


Bus Topology:

A shared cable links all network computers. The cable is typically terminated at each end, with one or more stations acting as the file server. Ethernet is an example of a bus system.

Advantages of Bus Network:

  1. Simple and economical installation.
  2. Suitable for temporary networks.
  3. One node failure doesn’t affect the rest of the network.
  4. Nodes can be attached/detached flexibly.
  5. Troubleshooting is easier compared to ring topology.


Ring Network:

Workstations are connected in a ring-like arrangement using a single network cable. Ring networks offer less security, as data for a specific machine might traverse other machines before reaching its destination.

Advantages of Ring Network:

  1. Orderly network with token-based access, reducing collision likelihood.
  2. Equal resource access for each node.
  3. Additional components don’t notably impact network performance.
  4. Easy installation and reconfiguration.

Disadvantages of Ring Network:

  1. Challenging to troubleshoot; failure location can be hard to identify.
  2. Adding/changing/moving nodes can disrupt the network.
  3. All nodes must be active for communication.
  4. Network failure if any cable or workstation malfunctions.


Hierarchical Network:

A specialized bus topology wherein terminals resemble branches on a tree. Extending the network is straightforward, and failure of a branch can be easily rectified.

Advantages of Hierarchical Network:

  1. Network remains unaffected by segment failure.
  2. Easy expansion capability.

Disadvantages of Hierarchical Network

  1. Heavily reliant on hub; hub failure affects the entire system.
  2. Maintenance is challenging, leading to higher costs.





  1. Introduction to the World Wide Web (WWW)

Definition of the World Wide Web:

The World Wide Web (WWW or simply the Web) is a system of interconnected documents and resources that are accessed over the Internet using web browsers. It’s a part of the broader internet and allows users to navigate through a vast collection of web pages, multimedia content, and other resources linked by hyperlinks. The web is based on the use of URLs (Uniform Resource Locators) to locate and access specific web pages, and it enables users to view text, images, videos, and other types of media from around the world.

Brief History of the World Wide Web

The World Wide Web was invented by British computer scientist Tim Berners-Lee in 1989 while he was working at CERN, the European Particle Physics Laboratory. He proposed the concept of a hypertext system that would allow researchers to share information across the internet. In 1991, Berners-Lee published the first web page and released the first web browser. This marked the beginning of the web as we know it. Over the years, the web has evolved significantly, leading to the development of multimedia-rich websites, social media platforms, online commerce, and a wide range of applications that shape modern digital life.

Basic Terminologies and Protocols for Websites:


  1. Website: A collection of web pages and multimedia content that are accessible through a specific domain name.
  2. Web Page: A single document on the web that contains text, images, videos, and other media.
  3. URL (Uniform Resource Locator): A web address used to specify the location of a resource on the internet. It consists of the protocol, domain name, and optional path.
  4. Domain Name: A human-readable name that corresponds to an IP address. It’s used to identify websites on the internet (e.g., www.example.com).
  5. Hosting: The service of storing and serving website files on servers connected to the internet.
  6. Browser: A software application used to access and view websites. Popular examples include Chrome, Firefox, Safari, and Edge.
  7. HTML (Hypertext Markup Language): The standard markup language used to create web pages. It structures content using elements and tags.
  8. CSS (Cascading Style Sheets): A language used to describe the visual presentation and layout of HTML elements on a web page.
  9. JavaScript: A scripting language used to add interactivity and dynamic behaviour to web pages.
  10. Responsive Design: Designing a website to adapt and display properly on various devices and screen sizes, from desktops to mobile phones.
  11. CMS (Content Management System): Software that helps users create, manage, and publish digital content on the web without requiring advanced technical skills.
  12. SEO (Search Engine Optimization): The process of optimizing a website’s content and structure to improve its visibility on search engines like Google.
  13. Domain Name System (DNS): The system that translates human-readable domain names into IP addresses, allowing users to access websites using names instead of numeric IP addresses.
  14. Web Server: A computer program that serves requested web pages to users’ browsers. Apache, Nginx, and Microsoft IIS are common web server software.
  15. Web Hosting: A service that provides storage space and resources for websites to be accessible on the internet.
  16. Hyperlink: A clickable element on a web page that, when clicked, takes the user to another web page or a different section of the same page.
  17. Navigation Menu: A collection of links that help users navigate through different sections or pages of a website.
  18. Viewport: The visible area of a web page within a user’s browser window, which may differ depending on the device and screen size.
  19. Alt Text: Descriptive text provided for images on a web page. It’s used for accessibility and search engine optimization.
  20. Meta Tags: HTML tags that provide metadata about a web page, such as title, description, and keywords. They influence how search engines display and index the page.
  21. Cache: Temporary storage of web page resources (like images, scripts, and styles) in a user’s browser to improve loading speed on subsequent visits.
  22. Cookie: A small piece of data stored on a user’s device by a website, often used for tracking, authentication, and personalization.
  23. E-commerce: Conducting business transactions, such as buying and selling products or services, over the Internet.
  24. Plug-in: A piece of software that adds specific features or functionalities to a website. Common examples include browser plug-ins and WordPress plugins.
  25. Widget: A small application or component that provides specific functionality on a website, such as a weather widget or social media feed.
  26. Responsive Images: Images that are served in different sizes and resolutions based on the user’s device, ensuring optimal display and performance.
  27. Breadcrumb: A navigational element that shows the user’s path from the homepage to the current page within a website’s hierarchy.
  28. Call to Action (CTA): A prompt on a web page that encourages users to take a specific action, such as signing up for a newsletter or making a purchase.
  29. API (Application Programming Interface): A set of rules and protocols that allows different software applications to communicate and interact with each other.
  30. Web Analytics: The collection, measurement, and analysis of data related to website usage and user behaviour to optimize performance and user experience.



  1. HTTP (Hypertext Transfer Protocol): The protocol used for transferring data (web pages, images, etc.) over the internet. It defines how requests and responses are formatted and processed.
  2. HTTPS (Hypertext Transfer Protocol Secure): A secure version of HTTP that encrypts data transmitted between the user’s browser and the web server, ensuring privacy and security.
  3. FTP (File Transfer Protocol): A protocol used to transfer files between a local computer and a remote server.
  4. SMTP (Simple Mail Transfer Protocol): A protocol for sending and receiving email messages.
  5. POP3 (Post Office Protocol 3): A protocol for receiving email messages from a mail server.
  6. IMAP (Internet Message Access Protocol): A protocol for accessing and managing email messages stored on a mail server.
  7. TCP/IP (Transmission Control Protocol/Internet Protocol): The foundational protocol suite of the internet, responsible for data transmission and routing.
  8. DNS (Domain Name System): The protocol used to translate domain names into IP addresses and manage domain name records.
  9. SSL/TLS (Secure Sockets Layer/Transport Layer Security): Protocols used to establish secure and encrypted connections between a user’s browser and a web server.
  10. HTTP/2: An updated version of the HTTP protocol that offers improved performance and efficiency for loading web pages.
  11. RSS (Really Simple Syndication): A protocol for distributing and gathering web content in a standardized format, often used for news feeds.
  12. WebSocket: A communication protocol that enables real-time, full-duplex communication between a client (such as a browser) and a server.
  13. XML (eXtensible Markup Language): A markup language similar to HTML, used to structure data for exchange between different systems.
  14. JSON (JavaScript Object Notation): A lightweight data interchange format commonly used for transmitting structured data between a server and a web application.
  15. REST (Representational State Transfer): An architectural style and set of constraints for designing networked applications, often used in web services.
  16. GraphQL: A query language and runtime for APIs that enables clients to request specific data, reducing over-fetching and under-fetching of data.
  17. FTPS (FTP Secure): An extension of FTP that adds a layer of security through encryption, protecting file transfers.
  18. SFTP (SSH File Transfer Protocol): A secure file transfer protocol that uses encryption and secure shell (SSH) for data protection.
  19. WebDAV (Web Distributed Authoring and Versioning): An extension of HTTP that facilitates collaborative editing and management of files on remote web servers.
  20. SMTPS: An encrypted version of SMTP that secures email communication by using SSL or TLS encryption.




  1. Cables & Connectors

Cables and connectors are essential components in various industries, particularly in technology, telecommunications, and electronics. They play a crucial role in transmitting signals, data, and power between different devices and systems. There are various types of cables and connectors designed for specific purposes, each with its own characteristics, compatibility, and use cases. Here’s an overview of common types of cables and connectors:

Types of Cables:

  1. Coaxial Cable: Used for transmitting cable television signals, internet connections, and other data. It consists of a central conductor, an insulating layer, a metallic shield, and an outer insulating layer.
  2. Ethernet Cable (Cat5e, Cat6, Cat7, etc.): Used for wired network connections, Ethernet cables are commonly used in home and office networks to connect computers, routers, switches, and other network devices.
  3. HDMI Cable: High-Definition Multimedia Interface cables are used to transmit audio and video signals between devices like TVs, monitors, projectors, and gaming consoles.
  4. USB Cable: Universal Serial Bus cables are widely used for connecting various devices like smartphones, tablets, printers, external hard drives, and more to computers and chargers.
  5. Power Cables: These cables provide electrical power from sources like power outlets or power supplies to devices such as computers, appliances, and electronic equipment.
  6. Fiber Optic Cable: These cables use light signals to transmit data over long distances with high speed and minimal signal loss. They’re commonly used in high-speed internet connections and telecommunications.
  7. Audio Cables (3.5mm, RCA, XLR): These cables are used to transmit audio signals between devices like headphones, speakers, microphones, and audio interfaces.


Types of Connectors:

  1. RJ-45 Connector: Used for Ethernet connections, these connectors are commonly found on the ends of Ethernet cables and are used to connect network devices.
  2. USB Connectors (Type-A, Type-B, Micro-USB, USB-C): These connectors are used with USB cables to establish connections between various devices and computers for data transfer and charging.
  3. HDMI Connector: Found on HDMI cables, these connectors transmit high-definition audio and video signals between devices like TVs, monitors, and gaming consoles.
  4. VGA Connector: Although becoming less common, VGA connectors are used to transmit analogue video signals between computers and monitors or projectors.
  5. XLR Connector: Commonly used in professional audio setups, XLR connectors are used for balanced audio connections, often found in microphones and audio mixers.
  6. BNC Connector: Used with coaxial cables, BNC connectors are often used for video and RF applications, such as in CCTV systems or certain types of networking equipment.
  7. DisplayPort Connector: Used for transmitting video and audio signals, DisplayPort connectors are commonly found on computer monitors and some other display devices.
  8. Fiber Optic Connector (LC, SC, ST, etc.): These connectors are used with fiber optic cables to ensure proper alignment and connection of the delicate fiber strands.

These are just a few examples of the many types of cables and connectors available. The choice of cable and connector depends on factors like the type of data or signal being transmitted, the distance involved, compatibility with devices, and the intended use case.



Theme 2  Computer Applications

  1. Database

A database is an application utilized to systematically store information. It comprises a structured collection of data or records.

A database management system (DBMS) is a compilation of computer software that empowers users to establish, generate, and uphold a database. Functioning as a computer application, a DBMS interacts with users, other applications, and the database itself to capture and analyze data.


The primary objective of a database management system (DBMS) is to facilitate the creation, definition, querying, and administration of a database. It serves as an intermediary between the database and end users or application programs, ensuring consistent organization and easy accessibility of data. Database Administrators oversee the database system, including access and security aspects.


DBMS Functions:

A DBMS enables users to generate, modify, and update data in database files. Its functions encompass:

  1. Simultaneous access to the same database concurrently.
  2. Establishment of security protocols for user access rights.
  3. Enhancement of data integrity within the database.
  4. Provision of a data dictionary for data descriptions.


Examples of Database Management Packages:

Diverse types of database management systems are available, including:

  1. Microsoft Access: Developed by Microsoft, it uses the Access Jet Engine to store data in its proprietary format. It allows importing and linking data from other databases.
  2. MySQL: An open-source DBMS, widely popular.
  3. Oracle: An object-relational database management system.
  4. Microsoft SQL Server: Developed by Microsoft, it stores and retrieves data as requested by applications, whether local or across a network.
  5. FileMaker: Initially a MS-DOS program, it’s now a cross-platform relational DBMS.


Database Terminology:

  1. Rows: Represent records.
  2. Columns: These are vertical and alphabetically labelled.
  3. Fields: Consist of related characters in a file.
  4. Characters: Single symbols in a file.
  5. Records: Comprise-related fields treated as a single entity.


To establish a computer-based database with MS Access.

Initiating MS Access involves the following steps:

  1. Open the Start Menu.
  2. Navigate to All Programs.
  3. Find Microsoft Office.
  4. Click on Microsoft Office Access.


Creating a Database

  1. From the displayed window, select “blank database.”
  2. On the right-hand side of the window, where the arrow is indicated in the image, click inside the file name text box and enter the desired database name.
  3. Click the “Create” command button. This action will generate a database with the provided filename.


Creating a File

  1. Click on the “Create” menu and choose “Table.”
  2. In the “All Tables” tab, right-click on any of the tables.
  3. Select “Design View.”

In the “Save As” dialog box, input the desired table name (e.g., Student Table) in the “Table Name” text box and confirm by clicking “OK.”

Database tables on a computer are structured with rows and columns. An MS Access table is organized into rows and columns, similar to the presented screen.

Each row holds records or different fields, determining the number of records in the table. In the example screen, the student table contains six records.

Columns usually represent fields within a database table, specifying the type of information stored. The shown screen includes three fields (data fields): REG. No., Surname, and First Name.


Creating Fields with Data Types

Fields are designated names relevant to the stored information. These field names are assigned data types, which govern the type of data they can accept. For instance, in the MS Access table above, the “Surname” field only accepts alphabetic characters, not numeric inputs like 10 or 500 as surnames.


To set the data type for a field in MS Access, follow these steps:

  1. In the design view of the created table, under the “Field Name” tab, input the field name.
  2. Under the “Data Type” tab next to the field name, click the dropdown menu and choose “AutoNumber,” as depicted below.

In the provided screen, the field “ID Number” would be assigned the “Number” data type, considering its numeric nature. Similarly, the “Surname” and “First Name” fields would both be assigned the “Text” data type.


Unique Identifier

A table incorporates a unique identifier, often referred to as a KEY. In MS Access, the initial field is usually set as the default primary key. To designate another field as the primary key, right-click the respective cell and select “Primary Key.”

Note: The key symbol should appear beside the field after setting it as the unique identifier. If it doesn’t appear, repeat the prior steps.


Creating a Database

In general, creating a database using any DBMS involves the following fundamental steps:

  1. Define the Database Structure

The structure specifies the preferred database organization. For a relational form, this includes RDBMS, table structure, row and column count, keys, and relationships.

  1. Specify Field Types

When crafting a database, each field must accept a specific type of input, known as a data type. This prevents incorrect input, ensuring database integrity. Data types may differ across DBMS, but they generally fall into categories like alphanumeric/text, numeric, date, boolean, memo, currency, AutoNumber, hyperlink, attachment, and OLE object.



  1. Graphics (Introduction to CorelDraw)

Computer Graphics refer to visuals that are generated using computers and encompass the creation, representation, and manipulation of image data through computational means.

Examples of Graphics Software Packages

  1. Paint
  2. CorelDraw
  3. Adobe Photoshop
  4. Harvard Graphics
  5. Print Master
  6. Ventura
  7. Photoshop Pro
  8. Adobe PageMaker


CorelDraw Environment and its Features

Title Bar:

The title bar displays the name of the active CorelDraw file and facilitates window repositioning.

Menu Bar:

With 11 pull-down menus, the menu bar contains all command options.


Rulers aid in positioning and sizing, optionally toggleable, and guidelines can be dragged off for assistance in drawing.

Scroll Bars:

Horizontal and vertical scroll bars allow shifting of the page view.

Drawing Windows:

The primary drawing area is the large white screen space, with a shadowed rectangle representing the printable page.

Roll-up Windows:

The Transform (Position) roll-up, situated on the left, offers dynamic control over CorelDraw operations, serving as a quicker alternative to invoking standard menu dialog boxes.

Status Bar:

The status bar showcases fill patterns, outline location, object movement, and absolute coordinates of selected objects.

Color Palette:

The colour palette enables swift application of coloured fills or outlines. Expanding the palette offers an extended range of colours.

Page Counter:

CorelDraw supports multi-page drawings, displaying the total page count along with navigation arrows.

Standard Toolbar:

The toolbar provides convenient access to commonly used features, many of which can also be accessed through the Menu Bar. CorelDraw offers various customizable toolbars, with the option to add buttons for frequently used commands.

Note: Keyboard shortcuts can often expedite actions more than toolbar usage. Once memorized, they streamline tasks:

  1. Ctrl + S = Save
  2. Ctrl + P = Print
  3. Ctrl + Z = Undo
  4. Ctrl + X = Cut
  5. Ctrl + C = Copy
  6. Ctrl + V = Paste



Theme 3  Problems – Solving Skills

BASIC Programming III (One dimentional array)

  1. Basic Programming (one-dimensional array): Basic programming refers to the fundamentals of computer programming. A one-dimensional array is a data structure that holds a collection of values of the same type, each identified by an index or a key.


  1. DIM Statement: In BASIC, the `DIM` statement is used to declare the dimensions and size of arrays. It allocates memory space for the array elements. For example: `DIM myArray(10)` declares an array named `myArray` with 11 elements (indexed from 0 to 10).


  1. For… Next Statement: The `For… Next loop is used for executing a block of code repeatedly for a specific number of times. It uses a loop variable that is incremented or decremented with each iteration. The loop continues until the loop variable reaches a specified value. Example:



   FOR i = 1 TO 10

       PRINT i

   NEXT i



  1. While… End Statement: The `While… End` loop is used for executing a block of code repeatedly as long as a certain condition remains true. The loop checks the condition before each iteration. Example:



   WHILE condition

       ‘ Code to be executed




Now, let’s write a BASIC program to calculate the area of 10 different rectangles using both the `While… End` loop and the `For… Next` loop.


Using For… Next Loop:



DIM length(10)

DIM width(10)

DIM area(10)


FOR i = 1 TO 10

    INPUT “Enter length of rectangle ” + STR$(i) + “: “, length(i)

    INPUT “Enter width of rectangle ” + STR$(i) + “: “, width(i)

    area(i) = length(i) * width(i)



FOR i = 1 TO 10

    PRINT “Area of rectangle ” + STR$(i) + “: “; area(i)




Using While… End Loop



DIM length(10)

DIM width(10)

DIM area(10)


i = 1

WHILE i <= 10

    INPUT “Enter length of rectangle ” + STR$(i) + “: “, length(i)

    INPUT “Enter width of rectangle ” + STR$(i) + “: “, width(i)

    area(i) = length(i) * width(i)

    i = i + 1



i = 1

WHILE i <= 10

    PRINT “Area of rectangle ” + STR$(i) + “: “; area(i)

    i = i + 1




Both versions of the program will calculate and display the areas of 10 rectangles using different types of loops. The choice between `For… Next` and `While… End` depends on the specific needs of the program and the desired looping behavior.


High-Level Languages (H.L.L.)

  1. Definition of High-Level Language:

A high-level programming language is a type of computer programming language designed to be human-readable and relatively easy to understand by programmers. High-level languages abstract away much of the complexity of computer hardware and provide more intuitive and user-friendly syntax for writing code.

They allow programmers to express algorithms and logic in a way that is closer to natural language, making it easier to develop software without dealing with the intricacies of the underlying machine architecture.


  1. Examples of High-Level Languages:

Some examples of high-level programming languages include:

  1. Python: Known for its simplicity and readability, Python is widely used for web development, data analysis, artificial intelligence, and more.
  2. Java: A versatile language used in various applications, including web development, Android app development, and enterprise-level software.
  3. C++: An extension of the C programming language that supports both procedural and object-oriented programming paradigms.
  4. JavaScript: Primarily used for front-end web development to create interactive and dynamic web pages.
  5. C#: Developed by Microsoft, C# is used for Windows application development and game development using the Unity engine.
  6. Ruby: Notable for its elegant syntax and is often used for web development with the Ruby on Rails framework.


3. Features of BASIC, C, PASCAL, and COBOL:

  1. BASIC (Beginner’s All-purpose Symbolic Instruction Code): Designed for beginners, it has simple syntax and is used for educational purposes and simple applications.
  2. C: Known for its efficiency and close-to-hardware capabilities, C is widely used for system programming and developing applications where performance is critical.
  3. PASCAL: Emphasizes structured programming and clear code readability. It was designed as a teaching language and for general-purpose programming.
  4. COBOL (COmmon Business-Oriented Language): Created for business data processing, COBOL features extensive support for handling data and has been used in legacy business systems.


Advantages of High-Level Language over Machine Language and Low-Level Language:

  1. abstraction: High-level languages abstract away the complexities of machine architecture, making it easier to write and understand code.
  2. Readability: High-level languages use more natural and human-readable syntax, improving code readability and maintainability.
  3. Productivity: High-level languages enable faster development as programmers can express complex tasks with fewer lines of code.
  4. Portability: Code written in high-level languages can be easily ported to different platforms with minimal changes, unlike machine-specific assembly code.
  5. Efficiency: While not as efficient as machine code or low-level languages, modern high-level languages often have optimizations that make their performance acceptable for most applications.
  6. Rapid Development: High-level languages often provide built-in libraries, frameworks, and tools that expedite the development process.
  7. Debugging: High-level languages offer better debugging tools and error messages, helping programmers identify and rectify issues more easily than in low-level languages.


In summary, high-level languages strike a balance between human readability and machine execution, making them a powerful choice for a wide range of programming tasks, from web development to system programming.



Theme 4  Coding Systems in Computer

  1. Overview of Number BASES

Number bases refer to ways of counting numbers. Counting started way back in the ancient times when began counting first, with his fingers. He counts in tens maybe because he has ten fingers and this is called decimal system of counting. There are different bases of counting,

Different number bases/system

Binary system

Octal system

Denary/decimal system

Hexadecimal system


Binary System

The word BI means two, so binary combination means numbers made up of a combination of only two numbers. It also refers to numbers in base 2.  The available digits in a binary system where 0 means off and 1 means ON.


Octal System

This is counting in eight i.e. base 8. It has 0,1,2,3,,4,5,6,7 digits.



This is counting in tens. They are also called decimal system. The decimal system has the following digits 0,1,2,3,4,5,6,7,8,9


Hexadecimal System

This system deals with numbers in base 16. It has the following digits 0,1,2,3,4,5,6,7,8,9,A,B,C,D.E,F (A=10, B=11, C=12, D=13, E=14 and F=15).



To convert a number in decimal system to other bases, the method of continuous division of the number by the new base number is used.

Convert 17ten to base 2

2         17

2          8  r  1

2          4  r  0                             17ten = 100012

2          2  r  0

2          1  r  0

0  r  1


Convert 58ten to base 2

2          58

2          29  r  0

2          14  r  1

2          7  r  0                          58ten = 1110102

2          3  r  1

2          1  r  1

0  r  1


Convert 248ten to octal

8          248

8          31   r  0

8          3    r   7              248ten = 370eight


0    r  3


Convert 312ten to base 16

16       312

16       19   r  8

16       1     r  3                   312ten = 13816

0         r  1


Convert 935ten to hexadecimal

16       935

16       58    r 7

16       3      r A                    935ten = 3A716

0      r 3


To convert numbers in other bases to denary system, expand the given number in powers of its base and evaluate.



1) Convert the following numbers to base ten

(i) 10012 (ii) 255eight (iii) 35416

(i) 10012 = 1 x 23 + 0 x 22 + 0 x 21 + 1 x 20

= 1 x 8 + 0 x 4 + 0 x 2 + 1 x 1

= 8 + 0 + 0 + 1

= 9ten

(ii) 255eight = 2 x 82 + 5 x 81 + 5 x 80

= 2 x 64 + 5 x 8 + 5 x 1

= 128 + 40 + 5

= 173ten


(iii)   35416 = 3 x 162 + 5 x 161 + 4 x 160

= 3 x 256 + 5 x 16 + 4 x 1

= 768 + 80 + 4

= 852ten



To convert from a number system to another one (not denary), it is usual to convert to base ten and then convert the base ten number to the new base number.

However, binary numbers can be converted to octal and hexadecimal numbers because of the fact that 23 = 8 and 22 = 16.



(1) Convert 110110two to base 8, base 16

(note 23 = 8 and 24 = 16)

(i) 1101102 = (1102) (1102)

= 66eight (1102 = 6ten)


(ii) 1101102 = (00112) (01102)

= 36hex (00112 = 3ten)

2) Convert 1110110two to base 16

1110110 = (01110110)two

= 7616


3) Convert 1000101two to base eight

1000101two = (001)(000)(101)

= 103eight


4) Convert 62eight to base two

62eight = 6                  2

110            010

= 110010two

5)     Change A0316 = A            0           3

1010    0000     0011

= 10100000011two




  1. Data Representation

Definition of Data Representation:

Data representation is the way in which information or data is encoded and stored in a format that computers can understand and manipulate. Since computers work with binary systems (1s and 0s), data from the real world needs to be translated into these binary values for processing. Data representation encompasses various methods and techniques to represent different types of data, including numbers, text, images, audio, and more.


Description of Data Representation Methods:

  1. Bits: The fundamental unit of data representation is the bit, which can hold a value of either 0 or 1. It’s the building block of all digital information.
  2. BCD (Binary Coded Decimal): BCD is a method to represent decimal numbers using a binary code. In BCD, each decimal digit (0-9) is represented by a four-bit binary code. For example, the decimal number 123 would be represented as 0001 0010 0011 in BCD.
  3. EBCDIC (Extended Binary Coded Decimal Interchange Code): EBCDIC is an encoding scheme used to represent characters, including letters, numbers, and symbols, in computers. It was mainly used by IBM in their mainframe systems. Each character is assigned an 8-bit binary code.
  4. ASCII (American Standard Code for Information Interchange): ASCII is a widely used character encoding standard that represents characters using a 7-bit binary code. It includes codes for uppercase and lowercase letters, numbers, punctuation marks, control characters, and more. ASCII has been a foundation for many modern character encoding standards.


  1. Display Character Set – ASCII (American Standard Code for Information Interchange):

ASCII is a character encoding standard that assigns unique numerical values to various characters used in the English language and some control characters. The ASCII standard uses 7 bits to represent each character, allowing for a total of 128 possible characters. The ASCII character set includes:

  1. Uppercase letters (A-Z)
  2. Lowercase letters (a-z)
  3. Digits (0-9)
  4. Punctuation marks (e.g., !, ?, &, %)
  5. Control characters (e.g., newline, tab, carriage return)
  6. Special characters (e.g., $, #, @)

These characters are assigned specific numeric values, which are then represented in binary form. For example, the ASCII value for the uppercase letter ‘A’ is 65, which in binary is 01000001. This binary value is what computers use to internally represent and process the character ‘A’.


Data representation methods like bits, BCD, EBCDIC, and ASCII are crucial for enabling computers to handle various types of data in a standardized and consistent manner. ASCII, in particular, provides a way to represent characters in a format that is widely understood and used across different computing systems.




Theme 5  Computer Ethics

  1. Security and Ethics

Definition of Security

Security refers to the protection of computer systems, networks, and data from unauthorized access, attacks, and damage. It involves measures and practices that aim to ensure the confidentiality, integrity, and availability of digital assets. Ethical considerations come into play when making decisions about security practices. Ethical behaviour in the context of security involves respecting privacy, avoiding harm, and adhering to laws and regulations. For instance, ethical hacking involves testing systems for vulnerabilities with the permission of the owner to help improve security.


  1. Sources of Security Breaches – Viruses, Worms, and Trojans:

   Viruses, worms, and Trojans are types of malicious software that can lead to security breaches:

  1. Viruses: These are programs that attach themselves to legitimate files and spread when those files are executed. They can corrupt or delete data and spread to other files and systems.
  2. Worms: Worms are self-replicating malicious programs that spread over networks, exploiting vulnerabilities in software. They can consume network resources and disrupt services.
  3. Trojans: Trojans are disguised as legitimate software but contain malicious code. They often trick users into running them, giving hackers unauthorized access to systems.


  1. Poorly Implemented or Lack of ICT Policy:

An ICT (Information and Communication Technology) policy outlines guidelines and rules for using technology in an organization. A poorly implemented or lacking ICT policy can lead to security vulnerabilities. Without clear guidelines, employees might engage in risky behaviours, use unauthorized software, or ignore security practices. A well-defined policy helps prevent security breaches by providing a framework for secure technology usage.


  1. Preventive Measures – Legal Issues, Web Contents, Privacy Crime, Hacking, Crime:

   Various preventive measures are in place to address security concerns:

  1. Legal Issues: Legal frameworks, regulations, and standards exist to hold individuals and organizations accountable for security breaches. Data protection laws, for example, require entities to safeguard personal information.
  2. Web Contents: Ensuring secure web content involves using encryption (HTTPS) to protect data in transit and regularly updating software to fix security vulnerabilities.
  3. Privacy Crime: Preventing privacy crimes involves protecting sensitive personal information from unauthorized access, often through encryption, access controls, and regular security audits.
  4. Hacking: Ethical hacking, or penetration testing, involves authorized individuals attempting to exploit vulnerabilities in systems to identify weaknesses before malicious hackers can.
  5. Cybercrime: Preventing cybercrimes like identity theft, fraud, and cyberattacks requires a combination of technical measures (firewalls, intrusion detection systems) and user education to recognize and avoid threats.

Overall, a combination of technical measures, policies, ethical considerations, and legal frameworks is crucial to maintaining security, protecting user privacy, and preventing various forms of cybercrime.

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