COMPUTERS & INFORMATION TECHNOLOGY – SHORT NOTES

Useful for SSC, RRB, PSC, UPSC basics, Banking, Insurance, Defence, Railway, Police & All State-Level Exams

1. Introduction to Computers

A computer is an electronic device that accepts data, processes it, and gives useful output.
Basic steps: Input → Processing → Output → Storage.

Characteristics

Speed
Accuracy
Automation
Storage
Versatility
Diligence

Types of Data

Analog – continuous (temperature, pressure)
Digital – discrete (0/1)
Hybrid – combines both

2. Generations of Computers

Computers evolved through five generations:

1st Generation (1940–1956)

Technology: Vacuum tubes
Language: Machine & Assembly
Example: ENIAC, EDVAC

2nd Generation (1956–1963)

Transistors replaced vacuum tubes
Smaller, faster, more reliable
Languages: FORTRAN, COBOL

3rd Generation (1964–1971)

Integrated Circuits (ICs) used
Monitors & keyboards introduced

4th Generation (1971–Present)

Microprocessors invented by Intel
Start of Personal Computers (PCs)

5th Generation (Present & Future)

AI, Machine Learning, Robotics, Quantum Computing

3. Types of Computers (Based on Size)

Supercomputer

Fastest computing machines
Uses: Weather forecasting, space research
Example: PARAM, Pratyush

Mainframe Computer

Large capacity, supports thousands of users
Banks, railways, insurance

Minicomputer

Mid-sized, multiple users
Industries, small organizations

Microcomputer

Personal computers, laptops

Workstations

High-end graphics and engineering tasks

4. Computer Hardware

Input Devices

Keyboard
Mouse
Scanner
Microphone
Barcode reader
Touch screen

Output Devices

Monitor
Printer (Inkjet, Laser, Dot-Matrix)
Speakers
Projector

Storage Devices

Primary Storage – RAM, ROM
Secondary Storage – HDD, SSD, USB
Optical – CD, DVD, Blu-ray

Memory Units

Bit
Byte = 8 bits
KB = 1024 bytes
MB = 1024 KB
GB = 1024 MB
TB = 1024 GB

5. Central Processing Unit (CPU)

CPU = Brain of the computer

Parts of CPU

ALU (Arithmetic Logic Unit)
CU (Control Unit)
Registers

CPU Processing Cycle

Fetch
Decode
Execute

6. Computer Software

System Software

Controls hardware
Examples:

Operating systems (Windows, macOS, Linux, Android)
Device drivers

Application Software

Used for end tasks
Examples:

MS Office
Browsers
Media players
Tally, Photoshop

Programming Languages

Generation	Examples
Low-level	Machine, Assembly
High-level	C, C++, Java, Python
Very High-level	SQL, MATLAB
Scripting	JavaScript, PHP

7. Operating Systems (OS)

An OS manages hardware & software.

Functions

Memory management
Process management
File management
Device management
Security

Types of OS

Single-user: Windows
Multi-user: Linux, UNIX
Mobile OS: Android, iOS
Real-time OS
Distributed OS

8. Internet & Networking

Network = Interconnection of computers.

Types of Networks

LAN – Office, school
MAN – City level
WAN – Global (Internet)
PAN – Bluetooth devices

Network Devices

Modem
Router
Switch
Hub
Repeater
Firewall

Networking Cables

Coaxial
Twisted pair (LAN cable)
Fiber optic

Communication Protocols

TCP/IP (Internet)
HTTP/HTTPS
FTP
SMTP (email)
DNS

Internet Terms

URL
Browser (Chrome, Firefox)
IP Address
Domain Name

9. Email & Cloud Computing

Email Components

To
CC
BCC
Subject
Attachments

Cloud Computing

Internet-based computing service.

Services:

IaaS – Infrastructure
PaaS – Platform
SaaS – Software (Google Drive, Gmail)

Benefits:

Cost-effective
Scalable
Accessible anywhere

10. Cyber Security

Cyber security protects systems from attacks.

Common Cyber Threats

Virus
Worm
Trojan
Spyware
Ransomware
Phishing
DDoS attack

Protection Measures

Antivirus
Firewall
Strong passwords
Two-factor authentication
Regular updates

11. Database Management

Database

Collection of structured data.

DBMS

Software to manage data
Examples: MySQL, Oracle, SQL Server

SQL Commands

DDL: CREATE, DROP
DML: INSERT, UPDATE
DQL: SELECT
DCL: GRANT, REVOKE

12. Number Systems

Computers use binary system.

Types

Binary (Base 2)
Octal (Base 8)
Decimal (Base 10)
Hexadecimal (Base 16)

Conversion between systems is frequently asked in exams.

13. Logic Gates

Basic building blocks of circuits.

Three Basic Gates

Other Gates

NAND
NOR
XOR
XNOR

14. MS Office Suite (Important for Bank & SSC)

MS Word

Editing documents
Formatting
Header/footer
Mail merge

MS Excel

Rows, columns, cells
Formulas: SUM, AVERAGE, MAX, MIN
Charts
Pivot tables

MS PowerPoint

Slides
Animations
Transitions

Useful for computer knowledge sections.

15. Emerging Technologies

Artificial Intelligence (AI)

Machines mimicking human intelligence.
Applications: Chatbots, robotics, automation.

Machine Learning

System learns from data.
Examples: Recommendation systems (YouTube, Netflix).

Deep Learning

Neural networks with many layers.

Internet of Things (IoT)

Interconnected smart devices.
Examples: Smart lights, smart meters.

Blockchain

Distributed digital ledger.
Used in → Cryptocurrency, secure transactions.

3D Printing

Manufacturing through layer-by-layer printing.

Augmented Reality (AR) & Virtual Reality (VR)

AR: Adds digital elements to real world
VR: Fully immersive digital environment

16. Mobile Technology

Operating Systems

Android
iOS

Mobile Networks

1G: Analog
2G: SMS
3G: Internet
4G LTE: High-speed data
5G: Low latency, IoT support

17. E-Governance in India

Technology used for public services.

Examples:

Aadhaar
Digital India
UMANG
BHIM UPI
DigiLocker
eCourts
National Digital Health Mission

Benefits

Transparency
Speed
Reduced corruption
Easy access

18. Computer Abbreviations (Important for Exams)

Term	Full Form
CPU	Central Processing Unit
RAM	Random Access Memory
ROM	Read Only Memory
HDD	Hard Disk Drive
SSD	Solid State Drive
USB	Universal Serial Bus
URL	Uniform Resource Locator
HTTP	Hyper Text Transfer Protocol
HTTPS	Hyper Text Transfer Protocol Secure
IP	Internet Protocol
GUI	Graphical User Interface
BIOS	Basic Input Output System
PDF	Portable Document Format
PNG	Portable Network Graphics
AI	Artificial Intelligence
ML	Machine Learning

19. Important Computer Inventors

Inventor	Contribution
Charles Babbage	Father of Computer
Ada Lovelace	First Programmer
Alan Turing	Father of AI
Bill Gates	Microsoft
Steve Jobs	Apple
Tim Berners-Lee	Invented WWW

20. Frequently Asked Exam Points

1 byte = 8 bits
1 GB = 1024 MB
Linux = Open-source OS
First computer = ENIAC
Brain of computer = CPU
Shortcut for copy = Ctrl + C
Primary memory = RAM
Binary digits = 0 and 1
Search engine = Google
Spreadsheet software = MS Excel

⭐ Conclusion

Computers & IT form a crucial part of all competitive exams. Understanding fundamentals like hardware, software, networking, internet, security, and emerging technologies increases your score in Computer Awareness, General Knowledge, and IT aptitude sections.

Computers & Information Technology Short Notes | Complete IT Basics for Competitive Exams