Digital Society and Computer Ethics

Digital Society

Stakeholder of Digital Society

Challenges of Digital Society


Computer Ethics

Importance of Computer ethics

Concept of Information Security


Information Security vs. Cyber Security


Information security principles






Information Security Policy


Information security measures


Concept of Cybercrime

Types of Cybercrime:


Malicious Software and Spam

Malicious Software

Different Types of Malware

Symptoms of Malware attack:


Protection from Cybercrime


Intellectual Property Right (IPR)


Types of Intellectual Property Right

Copyright and related rights:



Industrial designs:

Geographical indications:

Trade secrets:


Why should we promote and protect intellectual property?
Intellectual property rights (IPRs)


Digital Signature

Working mechanism of digital signature

Hash function:

Public Key Infrastructure (PKI):

Certificate Authority (CA):

Digital Certificate:


Advantage and Disadvantages of Digital Signature:

Advantage of Digital Signature: 

  1. Enhanced security and resistance to forgery.
  2. Authenticates sender’s identity.
  3. Ensures data integrity.
  4. Provides non-repudiation.
  5. Saves costs and time.
  6. Increases efficiency in workflows.
  7. Globally accepted for legal purposes.
  8. Positive environmental impact.
  9. Simplifies audit trail creation.
  10. Integrates well with digital workflows.

Disadvantage of Digital Signature: 

  1. Dependence on technology and digital infrastructure.
  2. Complex implementation and management.
  3. Key management challenges.
  4. Variability in legal recognition.
  5. Infrastructure requirements for both parties.
  6. Initial costs for implementation.
  7. User acceptance and familiarity concerns.
  8. Potential for misuse or fraudulent activities.
  9. Complex revocation processes.
  10. Risk of sensitive data exposure during transfer.

Cyber Law in Nepal

Area of Cyber Law

  1. Electronic and Digital Signature:
  2. Computer Crime:
  3. Intellectual Property:
  4. Data Protection and Privacy:
  5. Telecommunication Laws:

Cyber law in Nepal

Provisions included in the laws:

 ICT Policy in Nepal



Major Objectives


 Introduction to Multimedia

Benefits of Multimedia:

Interactive Multimedia


Category of Multimedia


Component of Multimedia



Graphics or image:










Advantage of Multimedia:

Disadvantage of Multimedia:


Application of Multimedia

1) Education:

2) Entertainment and Games:

      • Education is a human right for all.
      • Challenges like geography, technology, lack of higher education options.
      • Distance education options available: CBT (CD-based) and WBT (Web-based).
      • CBT offers CD-based courses, while WBT provides online courses.
      • Smart education tools in schools and colleges for interactive learning.
      • Many universities offer online degrees and distance education.
      • Learning becomes engaging and enjoyable.

3) Business:

      • Includes product demos, instant messaging.
      • Voice and live conferencing are excellent applications.
      • Engages audiences and widely used in programs.
      • Mechanics and various professionals can benefit.
      • Easy-to-use authoring tools for program creation.
      • Applications enhance smooth and effective operations.

4) Communication:

      • Multimedia tools allow cost-effective communication via live text, audio, and video chats.
      • This enhances daily communication’s ease, efficiency, and effectiveness.
      • Interactive multimedia-based social networking platforms like Facebook, Twitter, and Hi5 make communication faster across different time zones.
      • Communication through these platforms comes at a nominal cost.

5) Training:

      • Various systems available for training students.
      • Covers subjects from mathematics to complex medical procedures.
      • Incorporates audio clips and multi-angled views for practical skills.
      • Equipped with decision-making utilities for personalized training.
      • Uses video sequences to clarify concepts.

6) Web Page Designing:

      • Websites today serve as information sources for organizations and individuals.
      • Multimedia tools like images, audios, videos, and animations are used to interactively share information with users.
      • This approach enhances clarity in delivering information to recipients.
      • Various types of websites, such as news, educational, medical, business, and personal sites, adopt dynamic layouts for attractive and engaging web pages.

7) Journalism:

      • Modern journalists have expanded roles, including reporting, photography, editing, interpretation, and design.
      • Proficiency in multimedia tools is crucial for effectively designing and editing news articles.
      • Journalists gather diverse field footage to create captivating audio and visual content.
      • This multimedia approach ensures easy global accessibility to news content.

8) Engineering:

      • Software engineers frequently employ multimedia tools for tasks like computer graphics, simulations, and product demonstrations.
      • These tools have versatile applications, spanning scientific research to entertainment design.
      • Utilizing multimedia tools yields productive results for business entrepreneurs.
      • The impact of such usage extends to future societal implications.

9) Advertising:

      • Internet’s rise changed advertising.
      • Multimedia is crucial in advertising.
      • Used in both print and electronic ads.
      • Created using professional software.
      • Presents to target audiences effectively.

10) Virtual Reality:

      • Enables user interaction with computer-simulated environments.
      • Environment can mimic the real world or be completely different.
      • Used in training (pilot, combat, surgery) and games.
      • Built on multimedia technology.

11) Medicine:

Introduction to Web Development

Webpage and Website





Web Browsers and Search Engines


Web Development Process


Overview of Various Internet & Web Technologies

Overview of Internet

Uses of Internet

Misuses of Internet


Web Technology



Domain Name System


Content Management System (CMS)


Feature of CMS:


HTML the Language of the Web

Objectives of HTML:

  1. Create web pages for websites.
  2. Essential markup language for web pages.
  3. Allows adding graphical elements like videos, images, rich text.
  4. Facilitates customization with HTML5 and newer versions.
  5. Learn coding tools: code editor and browser developer tools.
  6. Create hypertext links to various online resources.

 Structure of HTML:


Published and Hosting (Web Publishing and Web Hosting)

Web Publishing:

Web hosting:


 HTML Tags vs. Attributes


Basic Tags of HTML

Heading Tag (H1 to H6) and Attributes (ALIGN)

Heading Tags


Font Tag and Attributes (Sizes: 1 to 7 Levels, BASEFONT, SMALL, BIG, COLOR)

<font> Tag


<basefont> Tag


Paragraph Formatting (P)

<p> Tag


Break Line BR

<br> Tag and <hr> Tag


Comment in HTML (<! >)

Comment Tag and Space Character


 Formatting Text (B, I, U, Mark, Sup, Sub, EM, BLOCKQUOTE, PREFORMATTED)

General Text Formatting


<marquee> Tag and <pre>

Special Characters

Ordered List- OL (LI, Type- 1, I, A, a; START, VALUE)



Unordered List – UL (Bullet Type- Disc, Circle, Square, DL, DT, DD)

Definition List




Inserting Image:

Inserting Object:


Anchor Tag and Hyperlink

Creating Hyperlink


Links to place in other HTML documents


Image Map


Table: Creating Table using TH, TR and TD tags

Creating Table 


Form: Creating form using Textbox, Radio, Checkbox, Text Area, Button

Creating Form




Creating Frameset


Introduction to HTML5 Elements including Audio, Embed, Source, Track and Video Attributes

Introduction to HTML5


HTML5 Graphics using canvas and svg Tags

<canvas> Tag


<svg> Tag


Structure of HTML5


Concept of Domain Name and Web Hosting

Domain  Name System 


Web hosting

Types of web hosting


Cascading Style Sheet

Introduction to Cascading Style Sheet (CSS)
 Inline CSS
Embedded CSS (Internal Style)
 External CSS


Some More on CSS

Class Style





Programming Concept

Computer Program

Characteristics of a Good Computer Program:

Introduction to Programming Language


 Low level, High level, 4 GL Programming Language (Types of Programming Language)

1. Low Level Language
a) Machine Language
b) Assembly Language

Merit of Assembly Language:

  1. Easier to understand and use than machine language.
  2. Easier to locate and remove the errors.
  3. It is easier to modify.
  4. It is easy to re-locatable.

Demerit of Assembly Language:

  1. It is machine dependent.
  2. Detailed knowledge of hardware is required.
  3. It uses machine level coding.
  4. Language processor (Assembler) is required to translate the coding.
2. High Level Language

Merit of High level language:

  1. Machine independent.
  2. Easy to write and learn then low level language.
  3. Easy to find out and remove the mistakes.
  4. High level programs are easy to maintain.
  5. Better documentation.

Demerit of High level language:

  1. Execute very slowly.
  2. Need language processor (Compiler, Interpreter) to translate the program.
  3. Some programs cannot be solved with these languages.
  4. Lower efficiency.
  5. Less flexibility.
a) Third Generation Language (3GL)

Merit of third generation language are:

  1. English-like statements, user-friendly.
  2. Faster program development.
  3. Ease of understanding and modification.
  4. Simple syntax error detection and debugging.
  5. Standardized and machine-independent.
  6. Examples: C, COBOL, FORTRAN, PASCAL, etc.

Demerit of third generation language are:

  1. Complexity for beginners
  2. Learning curve
  3. Hardware dependency
  4. Limited abstraction
  5. Efficiency concerns
  6. Challenging debugging
  7. Less control over hardware
  8. Limited portability
  9. Performance trade-offs
b) Fourth Generation Language (4GL)

Merit of fourth generation language are :

  1. No need to know machine details.
  2. Variety of languages available.
  3. Easy bug detection and debugging.
  4. English-like syntax, user-friendly.
  5. Faster and easier coding.
  6. Supports OOP and code reusability.

Demerit of fourth generation language are :

  1. Needs a compiler/interpreter for conversion.
  2. Conversion and execution time.
  3. Less efficiency than machine language.
  4. Inefficient resource usage.

Difference between 3GLs and 4GLs

Basis 3GLs 4GLs
Focus Emphasize procedure and algorithms. Emphasize on end-user outcomes and data handling.
Nature Low-level languages, closer to machine code. High-level languages, abstracted from machine code.
Abstraction Moderate level of abstraction. High level of abstraction.
Syntax Complex syntax requiring detailed coding. User-friendly, more natural language-like.
Syntax Suitable for system-level programming and complex applications. Designed for database querying, reporting, and rapid application development.
Examples C, C++, Java, Fortran. SQL, Python (in certain contexts), visual programming tools.


c) Fifth Generation Language (5GL)

Merit of fifth generation language are:

  1. Ease of Use
  2. Wide Adoption
  3. Rich Expression
  4. Contextual Understanding
  5. Flexibility
  6. Inclusivity
  7. Cognitive Load Reduction
  8. Natural Interaction
  9. Efficiency for Certain Tasks
  10. Communication with Non-Programmers

Demerit of fifth generation language are: 

  1. Complexity
  2. Limited Precision
  3. Learning Curve
  4. Performance Overhead
  5. Dependency on AI
  6. Resource Intensive
  7. Potential Ambiguity
  8. Limited Optimization
  9. Compatibility
  10. Reliance on Infrastructure

Compiler, Interpreter and Assembler (Language Translator)






Difference Between Compiler and Interpreter

Compiler  Interpreter
Translates the entire program before execution. Translates one line at a time, executing immediately.
Generates an object program (machine code). No separate object program generated.
Detected errors only after compilation. Detects errors line by line during execution.
Produces faster execution as code is pre-translated. Slower execution due to on-the-fly translation.
Used for languages like C, C++, Java. Used for languages like Python, JavaScript.


Syntax, Semantic and Runtime errors

Syntax Error:

Semantic Error:

Runtime Error:


Program Design tools


Characteristic of algorithm are:

  1. An algorithm must be simple and in easy language.
  2. An algorithm should have finite number of steps.
  3. The algorithm can be easily modified.
  4. The algorithm should be able to produce accurate result.





Feature of Flowchart are:

  1. Visual representation
  2. Sequential steps
  3. Decision points
  4. Connectors and arrows
  5. Symbolic notations
  6. Easy-to-understand
  7. Process visualization
  8. Logic illustration
  9. Hierarchical structure
  10. Language-agnostic



  1. It provides a clear overview of the entire problem.
  2. It is easy to draw and understand.
  3. It is independent of any programming languages.
  4. It serves as a guide for program coding.


  1. It is time consuming work.
  2. It is difficult to translate flowchart into a program.
  3. It is difficult to later time modification.
  4. Some time it may be miscommunication.






Control Structure: Sequence, Selection and Iteration





Absolute binary, BCD, ASCIL, and Unicode (Code)

Absolute Binary:










C Programming Language

 Introduction and Feature of C Language

Facts About C:

Feature of C:

  1. Easy learning due to the small command set.
  2. Follows structured programming.
  3. Provides machine independence.
  4. Supports modular programming.
  5. Acts as a bridge between high and low-level languages.
  6. Faster execution than other languages.
  7. Offers various data types and declarations.
  8. Includes numerous built-in functions.
  9. Powerful for commercial and hardware programming.
  10. Programs independent of CPU used.

Advantage of C: 

  1. Machine independent and portable.
  2. Considered the foundation of modern languages.
  3. Compiler widely accessible.
  4. Combines high-level and low-level capabilities.
  5. Known for fast execution.

Disadvantage of C:

  1. Lacks runtime checking.
  2. Challenging to fix errors in large programs.
  3. Doesn’t support object-oriented programming.
  4. Complexity may be difficult for beginners.

Structure of C program


Preprocessor and Header Files


Void main function ()




Compiling Process


C Preprocessor and Header Files


Character Set used in C

Special Characters:

 Use of Comments


Identifiers, Keywords and Tokens



Valid Identifiers

A1        B34        FIRST_NAME         x_1


Invalid Identifiers

1A        34AB        int       void        First-NAME        X.1


Basic Data Types in C


Primary Data Types:


Constants and Variables


Numeric Variable:

String Variable:



  1. Integer Constant

Decimal Integer          123       -31      0      +78

Octal Integer                 O26       O      O347     O676

Hexadecimal Integer OX2     OX8C        OXbcd        OX


2. Character Constant

                                   ‘A’          ‘B’          ‘h’          ‘2’          ‘6’


3. String Constant

                                    “VISHAL”          “1234”          “God Bless”          “!…?”


4. Symbolic Constant

                                       #define PI 3.14

                                      #define name “HSEB”

                                     #define area 100

5. Escape Sequence Constant


Difference between Variable and  Constant 

Variable Constant
Holds a value that can be modified during program execution. Holds a fixed value that cannot be changed during program execution.
Declared using a data type and an identifier (name). Declared using the const keyword.
Values can be assigned and reassigned as needed. Values must be assigned at the time of declaration.
Used to store and manipulate changing data. Used to represent unchanging data.


Types of Specifier


 Simple and Compound Statements

Simple Statement:

Compound Statement:


Operators and Expressions

Arithmetic Operators:


Relational Operators:

Logical Operators:

Assignment Operators:


Unary Operators:


Ternary Operator (? : operator):


The Comma Operator:



Type Casting and Conversions

Implicit Type Conversion:


Explicit Type Conversion:


Introduction to Library Functions


 Input/output (I/O) Functions

Other Input/Output Functions


Selection Control Statement: Decisions (if, if-else, if-else-if, nested and switch)

Introduction to Control Statement


Branching Statement

If statement:

If else statement:

If else if statement:

nested if else statement:

Switch case Statement:

Iteration Control Statement: Looping (while, do while, for nested)


while loop:


do while loop:


Difference between while loop and do while loop
while loop  do while loop
Condition is checked before entering the loop Condition is checked after executing the loop body.
If the condition is false initially, the loop might not execute at all. The loop body always executes at least once, even if the condition is false.
Execution might not enter the loop body if the condition is false from the beginning. Execution enters the loop body before the condition is checked.


for loop:


Nested Loop:


Infinite Loop:


Jumping Statement

break Statement:


continue Statement:


goto Statement:


Array: definition, types (1D and 2D), matrix addition and subtraction

Introduction to Array
Characteristics of Array:
Advantages of Array:
  1. Random Access: Elements can be accessed directly using array indices.
  2. Code Efficiency: Requires fewer lines of code for multiple elements.
  3. Simplified Access: Provides easy access to all elements.
  4. Efficient Traversal: Can be traversed easily using a single loop.
  5. Simplified Sorting: Sorting is easier with fewer lines of code.
Disadvantage of Array:
  1. Fixed Size: Array size is determined during declaration and cannot be changed.
  2. Limited Dynamic Behavior: Unlike linked lists, arrays are not dynamic in nature.
  3. Costly Insertion and Deletion: Inserting and deleting elements can be inefficient due to memory reallocation and shifting.
  4. Memory Management: Array elements need to be managed explicitly with new memory allocation.
  5. Static Structure: Array structure is static, making it less flexible for changing data requirements.


Types of Arrays


One Dimensional Array:

Array Initialization


Multi Dimensional Array:


String: Definition and String Function: strlen(), strcat(), strcamp(), strrev(), strcpy(), strlwr(), strupr()

Introduction to string


String Handling Functions


Array of Strings:

Introduction of Office Package

Microsoft Office

Concept of Word Processor

Feature of Word Processing:

  1. Document creation.
  2. Writing, editing, saving, and opening documents.
  3. Formatting options (font, size, color, style, etc.).
  4. Background, foreground, and word art features.
  5. Spelling checker and thesaurus for proofreading.
  6. On-screen reading and revision.
  7. Insertion of graphics, audio, and video.
  8. Ability to produce multiple copies of documents.

Applications of Word Processing:

  1. Document creation (letters, reports, memos)
  2. Academic work (research papers, assignments)
  3. Business communication (emails, contracts)
  4. Publishing (newsletters, brochures)
  5. Data analysis (tables, charts)
  6. Collaboration (track changes, comments)
  7. Legal documents (agreements, correspondence)
  8. Content for blogs/websites
  9. Creative writing (poems, stories)
  10. Personal use (resumes, letters)

Types of Word Processing

  1. MS Word
  2. Word Perfect
  3. Word Star
  4. Lotus Notes


Presentation Tools

Concept of Presentation

Feature of Presentation Software:

  1. Detailed topic overview
  2. Audio-video integration on slides
  3. Simple to interactive presentation
  4. Built-in design and animation tools
  5. 2D and 3D text editing
  6. Conversion to movie file


Application of Presentation Software:

  1. Creating slideshows for lectures and presentations.
  2. Business proposals and reports.
  3. Pitching ideas to investors.
  4. Educational content for classrooms.
  5. Marketing and sales presentations.
  6. Conference and seminar materials.
  7. Showcasing data visually.
  8. Interactive multimedia presentations.
  9. Collaborative team projects.
  10. Remote and online presentations.

Example Of Presentation Program:

  1. Microsoft PowerPoint
  2. Apple Keynote
  3. OpenOffice Impress
  4. Prezi, Google Slides
  5. Canva, Haiku Deck.


Types of Presentation

  1. Static Presentation:

2. Interactive Presentation:


Spreadsheet Package


Fundamental of SpreadSheet

  1. Grid of rows and columns.
  2. Cells store data, text, or formulas.
  3. Formulas perform calculations.
  4. Functions are predefined operations.
  5. Charts visualize data.
  6. Sorting and filtering organize data.
  7. Data analysis and modeling.
  8. Collaboration and sharing features.
  9. Common formats like Excel, Google Sheets.


Some Feature of SpreadSheet:

  1. Handles large data volumes.
  2. Provides built-in functions.
  3. Offers accurate results.
  4. Supports decision making.
  5. Includes word processing features.
  6. Offers database capabilities.
  7. Graphs, charts, and pivot tables for data representation.
  8. Integration with other software programs.

Application of SpreadSheet:

  1. Financial analysis and modeling.
  2. Budgeting and expense tracking.
  3. Data organization and management.
  4. Inventory management.
  5. Project planning and tracking.
  6. Statistical analysis and calculations.
  7. Business forecasting.
  8. Sales and revenue tracking.
  9. Employee scheduling.
  10. Data visualization and charts.


Database Management System



Database Management System (DBMS)

Advantage of DBMS:

  1. Controls database redundancy.
  2. Restricts unauthorized access.
  3. Offers storage structure and query processing techniques.
  4. Provides backup and recovery.
  5. Supports multiple user interfaces.
  6. Enforces data constraints.
  7. Reduces application development time.

Disadvantage of DBMS:

  1. Complex, time-consuming database design.
  2. High hardware and software startup costs.
  3. Database damage affects many applications.
  4. Significant conversion costs from file-based to database systems.
  5. Initial training required for programmers and users.
  6. Regular backup requirements leading to additional storage costs.


Introduction to Domain-specific Tools


Domain Specific Tools Advantages

School Management System

Feature of School Management System Project:

  1. Student management (enrollment, attendance, grades).
  2. Teacher management (schedules, assignments).
  3. Parent and guardian portals (access to info, communication).
  4. Administrative tools (staff, inventory, finances).
  5. Timetable creation and management.
  6. Communication tools (messaging, announcements).
  7. Library and resource tracking.
  8. Transportation management (routes, assignments).
  9. Exam and assessment management.
  10. Reports and analytics.
  11. Security and access control.
  12. Online admission and enrollment.


Inventory Management

Purpose of Inventory Management System Project:

  1. Efficiently track and manage inventory levels.
  2. Streamline stock ordering and restocking processes.
  3. Minimized overstocking or stockouts.
  4. Optimize resource allocation and utilization.
  5. Improve accuracy in inventory records.
  6. Facilitate timely reorder notifications.
  7. Enhance demand forecasting and planning.
  8. Reduce manual data entry and errors.
  9. Enable real-time visibility into inventory.
  10. Support effective cost management.
  11. Streamline vendor and supplier relationships.
  12. Enhance decision-making through data insights.
  13. Provide better control over inventory-related costs.

Feature of Inventory Management System Project:

  1. Product tracking and lifecycle management.
  2. Inventory control with reorder points.
  3. Barcode scanning for quick identification.
  4. Real-time updates and visibility.
  5. Reporting and analytics for data-driven decisions.
  6. Supplier management and relationships.
  7. Multi-location support for varied sites.
  8. User access control with permissions.
  9. Integration with other systems.
  10. Mobile app compatibility for on-the-go access.

Payroll Management System

Feature of payroll management system:

  1. Salary calculation and processing.
  2. Leave management.
  3. Bonus and incentive management.
  4. Tax calculation and deduction.
  5. Loan and advance tracking.
  6. Attendance and overtime tracking.
  7. Employee self-service portal.
  8. Direct deposit and payment methods.
  9. Tax compliance and reporting.


Financial Accounting

Objectives of financial accounting:

  1. Records transactions for analysis and statements.
  2. Calculates profit/loss for strategy adjustments.
  3. Assesses a company’s financial health (assets, liabilities).
  4. Share information with stakeholders for decisions.

Feature of financial accounting:

  1. Profit and loss calculation.
  2. Balance sheet preparation.
  3. Cash flow statement analysis.
  4. Audit trail and data accuracy.
  5. Tax calculation and compliance.
  6. Integration with other systems.
  7. Reporting and analytics capabilities.
  8. Data security and access controls.
  9. Financial statement generation.


Hotel Management System

Feature of Hotel Management Software:

  1. Reservation and booking management.
  2. Front desk operations.
  3. Guest check-in and check-out.
  4. Room allocation and availability tracking.
  5. Billing and invoicing.
  6. Housekeeping and maintenance scheduling.
  7. Restaurant and banquet management.
  8. Point of Sale (POS) integration.
  9. Online booking and payment processing.
  10. Guest communication and feedback.


Weather Forecasting System

Objective of Study:

  1. Predicting future atmospheric conditions.
  2. Providing timely and accurate weather information.
  3. Assisting public safety and disaster preparedness.
  4. Supporting agriculture, transportation, and industries.
  5. Enabling informed decision-making for various sectors.
  6. Enhancing understanding of climate patterns.
  7. Mitigating risks and minimizing impacts of severe weather.

Feature of weather forecasting software:

  1. Real-time data collection (temperature, humidity, wind).
  2. Meteorological model integration.
  3. Multi-day forecasts.
  4. Visualization and maps.
  5. Severe weather alerts.
  6. Historical data analysis.
  7. Regional and global coverage.
  8. User-friendly interfaces.

 Concept of Software

 Definition of Software:

Relationship Between Software and Hardware:

Categories of Software:

System Software:
  1. Operating System

Operating System (OS) Functions:

    1. Hardware management
    2. Process scheduling
    3. Memory allocation
    4. File system organization
    5. User interfaces
    6. Security control
    7. Device communication
    8. Error handling
    9. Networking support
    10. Software execution environment
    11. System services
    12. Virtualization (in some cases)
 2. Utility Software

Example of Utility Software are:


Disk Management:


Disk Cleanup:


File Management:

3. Language Processor


Application Software:

Used for a variety of purposes:

Types of Application Software
  1. Package Software:

Word Processing Software

Database Software

Spreadsheet Software

Multimedia Software

Presentation Software

Web Based Software

Mobile Apps

2. Tailored Software:


Concept of Operating System

Introduction of Operating System

  1. OS Kernel

2. Utility Software

3. OS Application


Role of Operating  System

  1. Memory Management:

2. Peripheral Management:

3. Hardware Interface Management:

4. Storage Allocation:

5. Time-Slicing (Swapping):

 Functions of Operating System:

1. Input Output (I/O) Management
2. Command Interpreter
3. Data Management
4.Files management
5. Memory Management
6. Job Management
7. Process Management

8. User Interface
9. Interrupt-handling
10. Security Management
11. Deadlock Prevention
12. Time Sharing
13. Virtual Storage Management


Operating System Terminology

Windows Operating System

 Introduction to GUI based Operating System and Its Features


GUI Advantages and Disadvantages:


  1. Beginner-friendly.
  2. Cut, paste, drag-and-drop info exchange.
  3. User-friendly interaction.


  1. High memory, processing needs.
  2. Slower than the command line.
  3. Can be complex for simple tasks.
  4. Main GUI components: Windows, Icons, Menus, Pointer (WIMP).
  5. Examples: Windows 10, macOS, Ubuntu.


Features of GUI:

  1. Visual interaction with images, icons.
  2. Mouse-based navigation.
  3. Windows: Separate on-screen areas for apps.
  4. Icons: Represent files, programs.
  5. Menus: Dropdown lists for commands.
  6. Pointing devices (e.g., mouse, touchpad).
  7. WYSIWYG: Accurate on-screen to print output.
  8. User-friendly, intuitive interface.
  9. Used in Windows, macOS, Linux distributions.


Open Source and Mobile Operating System

Concept of Open Sources Operating




Free Software

Introduction to UNIX, Linux

The UNIX Operating System

The Kernel:

The Shell:

The program:


Advantage of Linux:

Disadvantage of Linux:

Some LINUX commands

Syntax: mkdir directory

Example: mkdir ram

Syntax: cd directory

Example: cd hello

Syntax: my old_directory_namenew_directory_name

Example: mv testdir newnamedir

Syntax: rmdir directory

Example: rmdir directory

Syntax: cp source destination

Example: cp myfiles yourfile

Example: cal 12 1987

Syntax: cat files_name

Example: cat newyear

Syntax: clear


Linux Distributions

1. Ubuntu
2. Fedora
3. Linux Mint


Concept of Mobile Operating System

 Types of Mobile Operating System

1. Android OS (Google Inc.)

Feature of Android:


2. iPhone OS/IOS (Apple)

Feature of iPhone OS/iOS (Apple):


3. Windows Mobile (Windows Phone)

Feature of Windows Mobile:


4. BlackBerry OS (Research in Motion)

Feature of BlackBerry OS:


5. Symbian OS (Nokia)

Feature of Symbian OS (Nokia):

What is Number System?

Types of Number System:

  1. Non-positional Number System

2. Positional Number System

Radix of a Number System:


Why Binary number system is used in computer system?


Decimal/Binary/Octal/Hexadecimal Number System & Conversion

Decimal Number System:


Binary Number System:


Octal Number System:


Hexadecimal Number System:

Number System Conversion

Decimal to Other System Conversion

Conversion from decimal to binary


  1. Divide the decimal number by the base value of binary (2) and list the remainder.
  2. The process is continuing till the quotient becomes zero.
  3. Write the remainders left to right from bottom to top.


Convert (34)10 into Binary.


Given number: 34

Let’s convert it to binary:

∴ (34)10 = (100010)2

Fractional conversion (Decimal to Binary):


  1. Successively multiply the fraction by 2 (base 2) to generate binary digits.
  2. Repeat until the fraction becomes 0 or until the desired accuracy is reached.
  3. If the fraction becomes 0, terminate the process.
  4. If the fraction does not become 0 after 5 iterations, terminate the process after the 5th iteration.


Convert (23.84)10 into Binary.


Given number: 23.84

Let’s convert the non fractional part first:

∴ (23)10 = (10111)2

Now, let’s convert the fractional part:

∴ (.84)10 = (.11010)2


(23)10 + (.84)10 = (10111)2 + (.11010)2 

∴ (23.84)10 = (10111.11010)2


Converting Decimal to Octal


  1. Divide the decimal number by the base value of Octal (8) and list the remainder.
  2. The process is continuing till the quotient becomes zero.
  3. Write the remainders left to right from bottom to top.


Convert the decimal number 109 into octal.


Given number: 109

Let’s convert it to octal:

∴ (109)10 = (155)8

Fractional conversion (Decimal to Octal):


  1. Successively multiply the fraction by 8 (base 8) to generate binary digits.
  2. Repeat until the fraction becomes 0 or until the desired accuracy is reached.
  3. If the fraction becomes 0, terminate the process.
  4. If the fraction does not become 0 after 5 iterations, terminate the process after the 5th iteration.



Convert (23.84)10 into Octal.


Given number: 23.84

Let’s convert the non fractional part first:

∴ (23)10 = (27)8

Now, let’s convert the fractional part:

∴ (.84)10 = (.65605)8


(23)10 + (.84)10 = (27)8 + (.65605)8 

∴ (23.84)10 = (27.65605)8


Converting Decimal to Hexadecimal


  1. Divide the decimal number by 16 and list the remainder.
  2. The process is continuing till the quotient becomes zero.
  3. Write the remainders left to right from bottom to top.


  1. Convert the decimal number 53 into Hexadecimal number.


Given number: 53

Let’s convert it to octal:

∴ (53)10 = (35)16


  1. Convert decimal number 235 into Hexadecimal number.


Given number: 235

Let’s convert it to Hexadecimal:

Here, since it is hexadecimal values, we know:

14 = E

11 = B

∴ (235)10 = (EB)16

Fractional conversion (Decimal to Hexadecimal):


  1. Successively multiply the fraction by 16 (base 16) to generate binary digits.
  2. Repeat until the fraction becomes 0 or until the desired accuracy is reached.
  3. If the fraction becomes 0, terminate the process.
  4. If the fraction does not become 0 after 5 iterations, terminate the process after the 5th iteration.




Given number: 31.84

Let’s convert the non fractional part first:

Here, since it is hexadecimal values, we know:

15 = F

∴ (31)10 = (1F)16

Now, let’s convert the fractional part:

Here, since it is hexadecimal values, we know:

13 = D

10 = A

∴ (.84)10 = (.D70A3)16


(31)10 + (.84)10 = (1F)16 + (.D70A3)16 

∴ (31.84)10 = (1F.D70A3)16


Other System to Decimal Conversion

Converting From Binary to Decimal


  1. Multiply each binary digit with its place value i.e. positive powers of two with its positional weight.
  2. Add all the products.

Example: Convert Binary number 111111 into decimal no.

Given number: 11111

Let’s first find out positional weight for each binary digit:

Now, let’s convert: 

 = (1 × 25 + 1 × 24 + 1 × 23 + 1 × 22 + 1 × 21 + 1 × 20)

 = 32+16+8+4+2+1

 = 63

∴ (111111)2 = (63)10

Fractional conversion (Binary to Decimal):

Example:  Convert Binary number 110011.11into decimal no.

Given number: 110011.11

Let’s first find out positional weight for each binary digit:

Now, let’s convert: 

 = (1 × 25 + 1 × 24 + 1 × 23 + 1 × 22 + 1 × 21 + 1 × 20  + 1 × 2-1 + 1 × 2-2)

 = 32+16+0+0+2+1+0.5+0.25

 = 51.75

∴ (110011.11)2 = (51.75)10


Conversion from Octal to Decimal


  1. Multiply each octal digit with its place value (8) with its positional weight.
  2. Add all the products.

Example: Convert octal number 435 into Decimal number.

Given number: 435

Let’s first find out positional weight for each octal digit:

Now, let’s convert: 

= (4 × 82 + 3 × 81 + 5 × 80)

= (4 × 64 + 3 × 8 + 5 × 1)

= (256+24+5)

= 285

∴ (435)8 = (285)10

Fractional conversion (Octal to Decimal):

Solved examples of octal fractions to decimal fraction conversion

Example: Convert (21.21)8 into base 10

Given number: 21.21

Let’s first find out positional weight for each octal digit:

Now, let’s convert: 

= 2 × 81 + 1 × 80 + 2 × 8-1 + 1 x 8-2

= 2 × 8 + 1 × 1 + 2 × ( 1 / 8 ) + 1 × ( 1 / 64 )

= 16 + 1 + ( 0. 25 ) + ( 0.015625 )

= 17 + 0. 265625

 = 17.265625

∴ (21.21)8 = (17.265625)10


Conversion from Hexadecimal to Decimal


  1. Multiply each hexadecimal digit with its place value(16) with its positional weight.
  2. Add all the products.

Example: Convert hexadecimal number AB2 into decimal.

Given number: AB2 

Let’s first find out positional weight for each hexadecimal digit:

Here, since it is hexadecimal values, we know:

A = 10

B = 11

Now, let’s convert: 

(10 × 162 + 11 × 161 + 2 × 160 )

= (10 × 256 + 11 × 16 + 2 × 1)

= (2560 + 176 + 2) =2738

∴ (AB2)16 = (2738)10

Fractional conversion (Hexadecimal to Decimal):

Example: Convert ( E F . B 1 )16= ( ? )10

= E × 161 + F × 160 . B × 16-1 + 1 x 16-2

= 14 × 16 + 15 × 1 . 11 × ( 1 / 16 ) + 1 × ( 1 / 256 )

= 224 + 15 . ( 0. 6 8 7 5 ) + ( 0 . 0 0 3 9 0 6 2 5 )

= 239 + 0. 6914

= 239 . 691406

Therefore ( E F . B 1 )16 = ( 2 3 9 . 6 9 1 4 0 6 )10


Binary to Octal and Hexadecimal Conversion

Conversion from Binary to Octal

Method 1:

  1. Write the Binary number in group of 3 from right hand side.
  2. If any digits are inadequate for such group of 3, then add zeros before the number.
  3. Write its corresponding value of octal from the table or convert it to decimal as before.

Example: Convert Binary number 10110 into Octal.

Binary number: 10110

Grouped Binary Number: 010     110

Corresponding Octal Value: 2      6 [Taken from the table]


Given number: 10110

Let’s first find out positional weight for each binary digit:

Now, let’s convert: 

 = ( 0 × 22 + 1 × 21 + 0 × 20)

 = 0+2+0

 = 2


 = ( 1 × 22 + 1 × 21 + 0 × 20)

 = 4+2+0

 = 6

Concatenating above results. We get:

∴ (10110 )2 = (26)8


Method -2:

  1. First convert the Binary number into Decimal number.
  2. Now convert the decimal number into Octal number.

Example: Convert Binary number 10110 into Octal.

Given number: 10110

Let’s first find out positional weight for each binary digit:

Now, let’s convert to decimal first: 

= (1 × 2 4 + 0 × 23 + 1 × 22 + 1 × 21 + 0 × 20)

= 16 + 0 + 4 + 2 + 0

= 22

Therefore, (10110)2 = (22)10

Again, let’s convert decimal to octal:

Therefore (22)10 = (26)8

∴ (10110)2  = (26)8

Fractional conversion (Binary to Octal):

Example: Convert (0110 011.1011)2 into base 8

Binary number = (0110 011.1011)2

Group of 3 bit of Binary = (0 110 011 . 101 1)2

= (110 011 . 101 100)2

Now, let’s convert: 

 = ( 1 × 22 + 1 × 21 + 0 × 20)

 = 4+2+0

 = 6


 = ( 0 × 22 + 1 × 21 + 1 × 20)

 = 0+2+1

 = 3


 = ( 1 × 22 + 0 × 21 + 1 × 20)

 = 4+0+1

 = 5


 = ( 1 × 22 + 0 × 21 + 0 × 20)

 = 4+0+0

 = 4

Concatenting above results. We get:

Thus, (0110 011.1011)2 = (63.54)8

∴ (0110 011.1011)2  = (63.54)8


Conversion from Binary to Hexadecimal

Method -1:

  1. Write the binary number in a group of 4 from right to left. 
  2. If any digits are inadequate for such a group 4, then add 0 before the number as much is necessary. 
  3. Write the equivalent Hexadecimal number from the table or convert binary to decimal as before.

Example: Convert Binary number 10110 into Hexadecimal.

Binary Number: 10110

Grouped Binary Number: 0001     0110

Equivalent Hexadecimal number:   1     6 [taken from the table]


Now, let’s convert: 

 = ( 0 x 23  + 0 × 22 + 0 × 21 + 1 × 20)

 = 0+0+0+1

 = 1


 = ( 0 x 23  + 1 × 22 + 1 × 21 + 0 × 20)

 = 0+4+2+0

 = 6

Therefore, (10110) 2 = (16)16


Method -2:

  1. Convert the given binary number into Decimal number 
  2. Now convert decimal number into Hexadecimal number.

Example: Convert Binary number 10110 into Hexadecimal.

Let’s first find out positional weight for each binary digit:

Now, let’s convert to decimal first: 

= (1 × 2 4 + 0 × 23 + 1 × 22 + 1 × 21 + 0 × 20)

= 16 + 0 + 4 + 2 + 0

= 22

Therefore, (10110)2 = (22)10

Again, let’s convert decimal to octal:

Therefore (22)10 = (16)16

∴ (10110)2  = (16)16

Fractional conversion (Binary to Hexadecimal):

Method -1:

  1. Write the binary number in a group of 4 from right to left. 
  2. If any digits are inadequate for such a group 4, then add 0 before the number as much is necessary. 
  3. Write the equivalent Hexadecimal number from the table or convert binary to decimal as before.

Example: Convert (11110.01011)2 into Base 16

Binary Number: 11110.01011

Grouped Binary Number: 0001   1110   0101   1000

Equivalent Hexadecimal number:   1 14/E 5 8 [taken from the table]

∴  (11110..01011)2 =(1E.58)16


Binary number   = (11110..01011)2

Group of 4 bit of Binary = (0001 1110 . 0101 1000)2

Now, let’s convert: 

= (0 × 23 + 0 × 22 + 0 × 21 + 1× 20)

= 0 + 0 + 0 + 1

= 1


= (1 × 23 + 1 × 22 + 1 × 21 + 0 × 20)

= 8 + 4 + 2 + 0

= 14

= E


= (0 × 23 + 1 × 22 + 0 × 21 + 1 × 20)

= 0 + 4 + 0 + 1

= 5


= (1 × 23 + 0 × 22 + 0 × 21 + 0 × 20)

= 8 + 0 + 0 + 0

= 8

Concatenating above results. We get:

∴ (11110.01011)2 = (1E.58)16


Octal and Hexadecimal System to Binary Conversion

Conversion from Octal to Binary

Method – 1

  1. Write the equivalent 3 bits of binary number of octal from the table.

Example: Convert octal number 35 into Binary number.

Octal Number: 3 5

Equivalent Binary number: 011 101 [taken from the table]

Therefore, (35)8 = (011101)2


Method -2:

  1. First convert octal number into Decimal number.
  2. Now convert Decimal number into Binary number.

Example: Convert octal number 35 into Binary number.

Octal number: 3 5

Positional weight: 1 0

Conversion: = (3 × 81 + 5 × 80)

= 24+5

Therefore, (35)8 = (29)10

Thus, (35)8 = (11101)2


Conversion from Hexadecimal to Binary

Method – 1

  1. Convert the Binary number in the group of 4 bits for each hexadecimal number.
  2. Provide base 2 to the result.

Example: Convert Hexadecimal number A2C into Binary.

Hexadecimal Number: A 2 C

Equivalent Binary Number 1010 0010 1100

Therefore, (A2C)16 = (1010 0010 1100)2


Method – 2

  1. First convert the Hexadecimal number into decimal.
  2. Then convert the decimal number into a Binary number.

Hexadecimal Number: A 2 C

Positional weight: 2 1 0

Conversion: = (10 × 162 + 2 × 161 + 12 × 160)

(A=10, C=12 taken from the table)

= (10 × 256 + 2 × 16 + 12 × 1)

= (2560+32+12) = 2604

Therefore, (A2C)16 = (2604)10

Fractional conversion (Hexadecimal to Binary):


Octal to Hexadecimal Conversion and Vice Versa

Conversion from Octal to Hexadecimal


  1. Convert each octal digit into 3 bit of binary equivalent.
  1. Now, form the group of 4 digits of binary numbers from right hand side.
  2. Write the equivalent Hexadecimal value from the given table.

Example: Convert octal number 420 into Hexadecimal number.

Octal Number: 4 2 0

3 Bit of Binary equivalent: 100 010 000

Group of 4 bit of Binary digits 0001 0001 0000

Equivalent Hexadecimal number: 1 1   0

Thus, (420)8 = (110)16

Method -2:

  1. First convert octal number into Decimal number.
  2. Now convert Decimal number into Hexadecimal number.

Conversion from Hexadecimal to Octal

Method -1

  1. Convert each hexadecimal number into 4 bit of binary equivalent. 
  2. Then form the group of 3 bits of binary digits from right hand side.
  3. If any digits are inadequate for such group of 3, then add zero before the number.
  4. Now, write the equivalent octal value for each group from the table.

Example: Convert Hexadecimal number 183 into Octal.

Hexadecimal number: 1 8 3

4 bits of Binary equivalent 0001 1000 0011

3 bits of Binary grouping 000 110 000 011

Equivalent octal number   0   6   0   3

Hence, (183)16 = (603)8

Method – 2

  1. First convert Hexadecimal number into decimal number
  2. Then convert decimal number into octal number.

Hexadecimal number: 1 8 3

Positional weight: 2 1 0

Conversion: = (1 × 162 + 8 × 161 + 3 × 160)

= (256+128+3) 

= 387

Thus, (183)16 = (387)10

Fractional conversion (Hexadecimal to Octal):

 Binary Calculations

Binary Addition


Binary Subtraction

Note: Borrowing is necessary when we have to subtract a larger number from a smaller one. A borrow will cause a 1 in the minuend to become 0 and a 0 to become 1. In the second case the preceding 0s in the minuend are changed to 1s until a 1 can be changed to a 0.

Binary Multiplication

Binary Division

Binary division guidelines:

 One’s and Two’s Complement Method for Binary Subtraction 

1’s complement method for binary subtraction

Methods for binary subtracting by using 1’s complement.

  1. Make equal no. of bits by placing 0 in front of negative number to make equal with the first number.
  2. Convert 1’s complement of the second number i.e. 1 to 0 and 0 to 1
  3. Add it to the main value.
  4. If an overflow bit occurs, remove it and add it to the remaining number.
  5. If there is not extra bit, find 1’s complement of result in step 2 and add (-ve) sign.

Example: Subtract 11 from 100 by using 1’s complement.


2’s complement method for binary subtraction

Methods for binary subtracting by using 2’s complement

  1. Make equal no. of bits by placing 0 in front of negative number to make equal with first number.
  2. Convert 1’s complement of the second number i.e. 1 to 0 and 0 to 1 and adding 1 to inverted value.
  3. Add it to the main value.
  4. If overflow bit occurs, remove it and the remaining is answer.
  5. If there is no extra bit, find 2’s complement of result in step 2 and add (-ve) sign.

Example: Subtract 11 from 100 by using 1’s complement.


 Logic Function & Boolean Algebra

 Introduction to Boolean Algebra

Unique feature of Boolean Algebra:

  1. Boolean algebra: 0 and 1 values.
  2. No subtraction, division; only logical addition, multiplication.
  3. Unique laws: A + A = A, A . A = A.
  4. Distributive law: A + (B.C) = (A+B).(A+C).
  5. Graphical methods specific to Boolean algebra.

 Introduction to Boolean Values, Truth Table, Boolean Expression and Boolean Function

Truth Table


Boolean Expression or Functions

Basic Logical/Boolean Operation

AND Operation

OR Operation

NOT operation

Logic Gate

AND Gate

OR Gate 

NOT Gate


NOR Gate

X-OR Gate

X-NOR Gate

Universal Gate

NAND gate as Universal gate:

NOR gate as universal gate:

All NOR input pins connected to the input signal A give an output A’.

The figure below shows how the NOR gate can be used as OR gate.

An OR gate can be replaced by NOR gates as shown in the figure. The OR is replaced by a NOR gate with its output complemented by a NOR gate inverter.

The figure below show how the NOR gate can be used as AND gate.

An AND gate can be replaced by NOR gates as shown in the figure. The AND gate is replaced by a NOR gate with all its inputs complemented by NOR gate inverters.

Laws of Boolean Algebra

Duality Principle

For example:

Let us consider a Boolean expression

F = A + B . 0

Then it’s duality would be

FD = A . B + 1

And both expressions will be the same. It would be verified by the following truth table.

Boolean Postulates

Laws of Boolean Algebra
  1. Identify Laws

                        A + 0 = A                                        A . 1 = A

  2. Complement Laws

                        A + A’ = 1                                        A . A’ = 0

   3. Idempotent Laws

                       A + A = A                                        A. A = A

   4. Bounded Laws

                       A + 1 = 1                                          A . 0 = 0

   5. Absorption Laws

                      A + (A . B) = A                                A. (A + B) = A

   6. Commutative Laws

                     A + B = B + A                                  A . B = B . A

   7. Associative Laws

                    (A + B) + C = A + (B + C)             (A B) C = A (B C)

   8. Distributive Laws

                   A (B + C) = A B + A C                     A + (B C) = (A + B) (A + C)

  9. Involution Laws

                  (A’)’= A

10. De Morgan’s Laws

                 (A + B)’ = A’.B’                                (A.B)’ =A’+B’


Statement and Verification of Laws of Boolean  Algebra using Truth Table

Identity Law

These laws state that combining a Boolean variable with its complement (negation) results in the original variable.

(a) A + 0 = A

(b)  A . 1 = A


Complement Law

This law states that the sum of a Boolean variable and its complement is always equal to 1.

(a)  A + A’ = 1

(b) A . A’ = 0


Commutative Law

These laws state that the order of variables in an operation doesn’t affect the result.

(a) A + B = B + A

(b) A . B = B . A


Associative Law

These laws state that the grouping of variables in an operation doesn’t affect the result.

(a) A + (B + C)=(A + B) + C

The above table shows that (A + B) + C = A + (B + C) is equal for all possible combinations of inputs.

(b) A.(B.C)=(A.B).C

Distributive Law

These laws relate the operations of addition and multiplication.

(a) A (B + C) = A B + A C

The above table shows that A . ( B + C) = (A . B) + (A . C) is equal for all possible combinations of inputs.

(b) A + (B C) = (A + B) (A + C)

DeMoragan’s Theorem

Theorem 1

The above table shows that (A+B)’ = A’.B’ is equal for all possible combinations of inputs. Let us see: when the value of A = 0 and B = 0, the value of (A+B)’ = 1 and A’.B’ = 1. Similarly we can see all the combinations of A and B, all the time (A+B)’ = A’.B’ are equal.

Theorem 2

The above table shows that (A.B)’ = A’+B’ is equal for all possible combination of inputs. Let us see: when the value of A = 0 and B = 0, the value of (A.B)’ = 1 and A’.B’ = 1. Similarly we can see all the combinations of A and B, all the time (A.B)’ = A’+B’ are equal.

Simplification of Boolean Expression

Introduction to Computer

Definition of Computer:


Characteristics of Computer:


Advantages and Disadvantages of Computer


  1. Accurate and reliable machine.
  2. Much faster than humans.
  3. High storage capacity.
  4. Never feels tired and exhausted like a human being.
  5. Versatile device
  6. Error free result


  1. Expensive device
  2. Required skilled manpower to operate
  3. Discourage physical activities / affect human health
  4. Rise of computer crimes like hacking, virus, pornography etc.
  5. Need repair, update and maintenance frequently.
  6. Depend on electricity to work.


Application of Computers


  1. Online accounting facility like checking current balances, deposits etc. 
  2. ATM machines – interconnected computer system
  3. Internet banking for accessing accounts, transferring money, and paying bills.


  1. Work with CAM/CAD software packages like AutoCAD, CATIA, Etabs etc..
  2. Designing and developing machine drawings, building drawings, circuit drawings, 3D views etc.


  1. Diagnosing illness and monitoring patient’s status
  2. Look inside a person’s body and study in detail with the help of automated imaging techniques like UltraSound, CT scans, MRI scans etc.
  3. Storage of patients data in an efficient manner.


  1. Used as information resource, teaching aid, library system, result system, students record etc.
  2. Remote learning, audio-visual packages, interactive exercises etc.
  3. Online registration, mock exams, entrance exam and interviews
  4. Interactive learning and taking virtual field trips with the help of AR/VR 


  1. Book tickets for flight, bus, movies
  2. Online hotel reservations


  1. Information of defense system,  
  2. Secured database and record 
  3. Tracking, surveillance and controlling the flight, targeting ballistic missiles
  4. Control the access to atomic bombs


  1. Online buying and selling of goods and services
  2. Collaborating with business partners and suppliers, conducting electronic transactions
  3. File management, calculating the bills, office communication, administrative work, decision making etc.


  1. Working with graphics and images. Ex: Photoshop
  2. Audio or video composition, editing. Ex: Adobe Premiere Pro, Da Vinci Resolve
  3. Making special effects like VFX in science fiction movies.

Desktop publishing:

  1. Create page layouts for magazines, newspapers, books etc. Ex: Adobe Illustrator, InDesign etc.


  1. Real time communication(chatting, video call) over the internet. Ex. Zoom call
  2. Connects with people around the world with the help of emails, social media etc. For example Gmail, Facebook, Instagram, WhatsApp etc.


  1. Data processing and maintenance of database of citizens record
  2. Create paperless environment
  3. Aid in country’s defense organizations like missile development, satellite, rocket launches etc.

Planning and Scheduling:

  1. Store contact information, generate plans, schedule appointments and deadlines etc.
  2. For example: Project management with Jira, Gmail Scheduling etc.


History of Computer

  1. Mechanical Calculating Era:

            a)  Abacus

        1. Abacus: earliest calculating device, still in use today.
        2. Originated in China 3000 years ago.
        3. “ABACUS” derived from Roman words “ABAC” and “ABAX” (dust and sand).
        4. Wooden frame, beads on parallel bars for counting.
        5. Experienced users perform fast calculations, rivaling electronic calculators.

           b) Napier’s Bone

        1. 1617AD: John Napier invented rods for simple multiplication.
        2. ‘Bones’: rods with carved numbers for easy multiplication.
        3. Napier is better known for inventing logarithms.

         c) Slide Rule

        1. 1620 AD: William Oughtred invented the Slide Rule, combining logarithm and Napier’s bones.
        2. Slide Rule used logarithmic scales for rapid multiplication, division, and other calculations.
        3. Engineers and mathematicians extensively used slide rules until electronic calculators replaced them.

        d) Pascaline

        1. Around 1642 AD: Blaise Pascal invented a simple mechanical calculator.
        2. Pascal’s calculator used gears and wheels to register numbers.
        3. It could add and subtract easily but couldn’t multiply or divide.
        4. Recognized as the first mechanical calculating device.

        e) Stepped Reckoner

        1. Stepped Reckoner: Mechanical calculator invented by Gottfried Wilhelm Leibniz in 1671AD.
        2. Modified the Pascaline and made his own.
        3. Used until replaced by electronic calculators in the 1960’s.

        f) Babbage ‘s Engine (Difference Engine and Analytical Engine)

        1. 1822AD: Charles Babbage developed the Difference Engine for algebraic equations.
        2. 1833 AD: Designed Analytical Machine, inspired by Jacquard’s punched cards.
        3. Prototype of the modern computer with input, storage, output, and program control.
        4. Babbage’s ideas ahead of his time, technology limitations prevented completion.
        5. Babbage is known as the Father of Modern Computers.

      g) Lady Augusta Ada

        1. Ada Lovelace: Mathematician, Lord Byron’s daughter.
        2. Assisted Babbage, advocated a binary system.
        3. First computer programmer.
        4. “Ada” programming language named after her by U.S. Defense.
        5. Recognized for significant computer science contributions.

      h) George Boole

        1. 19th Century (1950s): English mathematician, symbolic logic.
        2. Discovered Boolean Algebra in mathematics.
        3. Pioneered modern electronic computers with 0 and 1 representation.
        4. Introduced “on” and “off” states for communication.

     i) Tabulating Machine

        1. 1886: Hollerith’s Tabulating Machine inspired by Jacquard.
        2. Used punch cards for faster census calculation.
        3. Founded Tabulating Machine Company (TMC).
        4. 1923: TMC merged, formed IBM.
        5. IBM: Top computer manufacturer today.


2) Electro-Mechanical Era:

     a) Mark I

        1. Also known as IBMASCC (IBM Automatic Sequence Control Calculator).
        2. 750,000 parts, 500 miles of wire, complex.
        3. Huge: 50ft long, 8ft high, 3ft wide.
        4. Dimension: 50 feet long, 8 feet high, 3 feet wide. 
        5. About  32 tons and had 18000 vacuum tubes
        6. Operations: Add, subtract, multiply, divide, table reference.
        7. Handled up to 23-digit numbers.
        8. Multiplication took 3-5 seconds.
        9. Mark II: Used high-speed electromagnetic relays, not electro-mechanical counters.

     b) ABC(Atanasoff Berry Computer)

        1. 1942: Atanasoff and Berry invented ABC.
        2. First electronic special-purpose computer.
        3. Designed for complex math problems like linear equation.
3) Electronic Computers Era:

     a) ENIAC

        1. ENIAC: First general-purpose electronic computer.
        2. Invented in 1946 by Mauchly and Eckert.
        3. Created for US armed forces.
        4. Capable of 5000 additions, 300 multiplications per microsecond.
        5. Used over 18000 vacuum tubes, high power consumption.


      b) J.V. Neumann

        1. 1945: J.V. Neumann discovered the stored program concept.
        2. Crucial for modern digital computer development.
        3. Improved speed, flexibility, efficiency.
        4. Known as “father of stored programs.”


     c) EDSAC

        1. 1949: EDSAC created by Maurice Wilkes.
        2. Used J.V. Neumann’s techniques.
        3. Introduced “Initial Orders” (first assemblers).
        4. Enabled symbolic programming instead of machine code.


      e) EDVAC

        1. 1952: Mauchly, Eckert, and von Neumann create EDVAC.
        2. First stored-program computer, storing instructions and data.
        3. Marked crucial step in modern computing evolution.


      f) UNIVAC

        1. UNIVAC was invented in 1951 by John Mauchly and J.P. Eckert.
        2. Used magnetic tape for input and output.
        3. Installed in 1954 at the office of General Electric Company.
        4. Marked the arrival of commercially available digital computers for business and scientific purposes.


Inventors J. Presper Eckert and John Mauchly Maurice Wilkes John von Neumann J. Presper Eckert and John Mauchly
Year of Invention 1946 1949 1952 1961
Memory No stored program concept Mercury delay lines Stored-program concept Mercury delay lines
Programming Wired plugboards Paper tape and later magnetic tape Binary-coded instructions stored in memory Binary-coded instructions stored in memory
Applications Ballistic trajectory calculations, cryptography, etc. Scientific calculations, computer science research Influenced subsequent computer architectures Business data processing, scientific calculations


Evolution of Computer Technology

First Generation of Computer (1940 – 1956)

Feature of First Generation Computer:

  1. Vacuum Tubes: Key hardware, large size, short lifespan.
  2. Slow speed, challenging maintenance, limited programming.
  3. Machine-level language for coding.


Vacuum Tube


Second Generation of Computer (1956 – 1963)

Feature of Second Generation Computer:

  1. Transistors: Key hardware advancement.
  2. Magnetic core memory: Reliable, smaller primary storage.
  3. Lower power consumption, no heat.
  4. High-level programming (FORTRAN, COBOL).
  5. Commercial and scientific use.

Examples: IBM 1401, Honeywell 400, CDC 1604, ICL 1901 etc.



Third Generation of Computer(1964 – Early 1970s)

Feature of Third Generation Computer:

  1. They are built with IC chips with SSI (Single Scale Integration) and MSI (Middle Scale Integration) technologies.
  2. Larger magnetic core memory.
  3. Larger capacity magnetic disk and tapes.
  4. More flexible with input/output devices.
  5. Smaller in size and had better performance and reliability.
  6. Extensively used high level programming language.
  7. Mini computers emerged from this generation.
  8. Easier to upgrade than the previous generation system.
  9. Operating system program used to control input/output in this generation.

Examples: IBM 360/370, CDC 6600, PDP 11, ICT 1900, Honeywell 2200 series etc.

Integrated Circuits (ICS)


Fourth Generation of Computer (Early 1970s – Till Date)

Feature of Fourth Generation Computer:

  1. Used VLSI/Microprocessor as a key hardware technology.
  2. Semiconductor memories replaced magnetic core memories.
  3. Larger storage capacity and fast processing speed.
  4. Personal /desktop computers were introduced.
  5. Small, affordable, reliable and easy to use.
  6. GUI based operating system introduced. (Windows)
  7. High speed computer networking also developed.
  8. Introduced electronic mailing system.

Examples: IBM PC, APPLE II, Motorola M6800, DCM, Burroughs B7700 etc.



Fifth Generation of Computer (Present and Beyond)

Feature of Fifth Generation computer:

  1. Utilization of Ultra Large Scale Integration (ULSI) technology.
  2. Incorporation of superconductors using materials like Gallium Arsenide (GA) or Biochips.
  3. Integration of hardware and software to achieve Artificial Intelligence (AI) comparable to human intelligence.
  4. Development of Expert systems as crucial software components.
  5. Expected to dominate other technologies in the future.

Examples: PARAM super computer, IBM notebooks, SUN, IBM SP/2 etc.

Artificial Intelligence(AI)


Feature First Generation Second Generation Third Generation Fourth Generation Fifth Generation
Time Period 1940s – 1956s 1956s – 1963s 1964s – 1970s 1970s – Till Date Present and Beyond
Main Component Vacuum Tubes Transistors Integrated Circuits Microprocessors AI, Quantum Tech
Size Large Smaller Smaller Much Smaller Shrinking
Speed Slow Faster Faster Much Faster Varies
Programming Languages Machine Language Assembly Language High-Level Languages High-Level Languages AI Languages
Memory Magnetic Drum, Delay Lines Core Memory Semiconductor Memory RAM, Hard Drives RAM, SSDs, Cloud Storage
Applications Scientific, Military Business, Scientific Business, Real-time Personal Computers, AI, Big Data
Power Consumption Very High High Moderate Moderate to Low Varies
Examples ENIAC, UNIVAC I IBM 1401, CDC 1604 IBM System/360, PDP-8 Intel 8086, Macintosh IBM Watson, Google’s Quantum Supremacy, various AI systems


Measurement Unit of Processing Speed and Storage Unit 

Computer processing Speed


Computer Processing Speed

Units Equivalent
1000 th of a second 1 Milliseconds (MS)
1000 th of a milliseconds 1 Microseconds (μs)
1000 th of a microseconds 1 Nanosecond (ns)
1000 th of a nanoseconds 1 Picoseconds (ps)
1000 th of a picoseconds 1 Femtoseconds (fs)


Measurement Unit

0,1 1 bit
4 Bit 1 Nibble
8 Bits or 2 Nibble 1 Byte, 1 Character
1024 Bytes 1 Kilobyte (KB)
1024 KB 1 Megabyte (MB)
1024 MB 1 Gigabyte (GB)
1024 GB 1 Terabyte (TB)
1024 TB 1 Petabyte (PB)
1024 PB 1 Exabyte (EB)


Super, Mainframe, Mini and Microcomputers


Characteristics or applications of supercomputers:

  1. Excellent results in animations.
  2. Virtual testing of nuclear weapons and critical medical tests.
  3. Studying and understanding climate patterns for weather forecasting.
  4. Designing flight simulators for pilot training.
  5. Diagnosing critical diseases, brain injuries, and strokes accurately.
  6. Scientific research analyzing data from exploring the solar system and Earth’s movements.
  7. Predicting fog and pollutants in the atmosphere for smog control.
  8. Enhancing security by decrypting passwords for protection.

Example: PARAM, CRAY -1, CDC Cyber 203, Cray XMP etc.

Uses: Weather Forecasting, Aircraft and Space Engineering, Scientific Researcher, etc.


Mainframe Computer

Characteristics of Mainframe Computers:

  1. Process huge amounts of data, e.g., millions of transactions in the banking sector.
  2. Long life span, running smoothly for up to 50 years after proper installation.
  3. Excellent performance with large-scale memory management.
  4. Can distribute workload among other processors and terminals.
  5. Fewer chances of errors or bugs, quickly fixable without performance impact.
  6. Ability to protect stored data and ongoing information exchange.

Examples: IBM 370, CYBER 170, UNIVAC 1100 series etc.

Uses: Industries, Banking, Insurance companies, Airlines, Air Traffic Control, etc.



Characteristics of Minicomputer:

  1. Lightweight, portable, and easy to carry.
  2. Less expensive than mainframe computers.
  3. Fast processing capabilities relative to its size.
  4. Long-lasting battery life.
  5. Operates without the need for a controlled environment.

Example: IBM sys/3, PDP-II, Hewlett Packard 3000 etc.

Uses: University, Scientific Research, Industries, etc.


Micro Computer

Characteristics of a microcomputer:

  1. Smallest in size among all computer types.
  2. Limited software compatibility.
  3. Designed for personal work with one user at a time.
  4. Less expensive and user-friendly.
  5. No special skills or training required.
  6. Often equipped with a single semiconductor chip.
  7. Capable of multitasking, such as printing, scanning, browsing, and video watching.

Example: IBM PCs, Apple/Macintosh, Dell, etc

Uses: Entertainment, Desktop, Business, School, College, Personal, etc.

Difference between mini and micro computers
Mini computer Micro computer
more powerful than micro computers. less powerful than mini computers.
comparatively more expensive. comparatively cheaper.
bigger in size so that nearly 50 terminals can work smaller in size & can work only single terminal.
not general purpose. general purpose computers.


Desktop Computer




Tablet PC

Smart Phone



Mobile Computing and its Application



Application of Mobile Computing:








Emergency Situation


 Computer system and I/O devices

Concept of Computer Architecture and Computer Organization
 Components of Computer System

Integrated components working together for a desired result.

Input Unit:

Processor/Central Processing Unit:


Control Unit

Arithmetic Logic Unit(ALU)

Memory/Storage Unit

Auxiliary Memory or Storage

Output Unit:


Function of Microprocessor:

Characteristics of Microprocessor

Components of Microprocessor

The components of a microprocessor (CPU) include:

Bus System


Types of Bus:

Address Bus:

      • Transfers memory or I/O device addresses
      • Unidirectional
      • Intel 8085 microprocessor’s Address bus: 16 bits
      • Allows addressing of 65,536 memory locations

Data Bus:

Control Bus:

Primary Memory

Random Access Memory(RAM):

Read-only Memory (ROM):

Cache Memory:

L1 and  L2 Cache :



Secondary Memory

Storage Device:

Magnetic Disk:

Hard Disk:

Floppy Disk:

Flash Memory:

Pen Drive:

Memory Card:

Magnetic Tape:

Optical Disk:





Blu-ray Disc:

Other External Storage Device:

Memo Stick:


Difference Between Primary Memory and Secondary Memory
Primary Memory Secondary Memory
Main memory of the computer. Long-term storage.
Fast access speed. Slower access speed.
Volatile (data is lost when powered off). Non-volatile (data is retained when powered off).
Limited capacity. Larger capacity.
More expensive per unit of storage. More cost-effective for larger storage needs.


 Input Devices





Magnetic Ink Character recognition (MICR):

Optical Mark Recognition (OMR):

Optical Character Recognition(OCR):

Barcode Reader:

Digital Camera:

Touch Screen:




Output Devices


CRT Monitor

Advantage of CRT Monitor:

  1. Good color reproduction and image quality.
  2. Suitable for graphic-intensive applications and gaming.
  3. Wide viewing angles with consistent colors.

Disadvantage of CRT Monitor:

  1. Bulkier and heavier than modern monitors.
  2. Higher power consumption.
  3. Limited resolution options compared to LCD and LED monitors.
  4. Susceptible to screen flickering and eye strain.
  5. Phased out due to advancements in LCD and LED technology.


Liquid Crystal Display (LCD) Monitor

Advantage of LCD:

  1. Slim and lightweight design, making them portable and easy to handle.
  2. Low power consumption, resulting in lower energy costs.
  3. Minimal heat production, contributing to a cooler working environment.
  4. Sharp and clear image quality with minimal flickering.
  5. Suitable for high-resolution displays, ideal for multimedia and gaming.

Disadvantage of LCD:

  1. Limited viewing angles can cause color and brightness distortion.
  2. Slower response times can lead to motion blur in fast-paced content.
  3. Potential for dead or stuck pixels, which can be distracting.
  4. Higher cost compared to CRT monitors, especially for larger sizes and high-end models.
  5. Limited color reproduction compared to other display technologies like OLED or QLED.


Light Emitting Diode (LED) Monitor

Advantage of LED Monitor

  1. Energy-efficient and eco-friendly.
  2. Slim and lightweight design.
  3. Long lifespan and durability.
  4. Brighter and more vibrant colors.
  5. No flickering and better contrast ratio.

Disadvantage of LED Monitor

  1. Higher cost.
  2. Limited viewing angles.
  3. Potential for backlight bleeding.
  4. Color accuracy issues.
  5. Potential manufacturing defects.



Impact Printers/Dot-matrix Printers


Non impact Printers / Inkjet Printers / Laser Printers

Non-impact Printers:

Inkjet Printers:

Laser Printers:


Difference between Impact printer and Non impact printer
Impact Printer Non Impact Printer
1.Mechanical touch between printing head and paper. 1. No mechanical touch between printing head and paper.
2. Low efficiency compared to non-impact printers. 2. Higher efficiency compared to impact printers.
3. Slower printing speed. 3. Faster printing speed.
4. Produces sound during printing. 4. Silent operation during printing.
5. Capable of printing multiple copies (carbon copies) simultaneously. 5. Capable of printing single copies at a time.
6. Not suitable for printing graphics. 6. Suitable for printing graphics.
7. Low cost. 7. High cost.
8. Example: Dot matrix, daisy wheel, line printer 8. Example: Inkjet printer, Laser printer, Thermal printer.



 Hardware Interfaces

Serial Port:

Parallel Port:

USB Port: