Computer Fundamentals

🧠 1. Introduction to Computers

🔹 Definition

A computer is an electronic device that accepts data as input, processes it according to instructions (programs), and produces useful output.

🔹 Characteristics

Feature	Description
Speed	Performs calculations very fast.
Accuracy	High precision; errors only occur due to human/program mistakes.
Storage	Stores large amounts of data.
Automation	Works automatically after instructions are given.
Versatility	Performs multiple tasks.
Diligence	No fatigue or boredom.

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🧩 2. Components of a Computer System

A computer system consists of Hardware + Software + Data + Users.

🔸 (A) Hardware

Physical parts of a computer that you can see or touch.

Examples:

• Input Devices (Keyboard, Mouse)
• Output Devices (Monitor, Printer)
• CPU, RAM, Hard Disk, Motherboard, etc.

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🔸 (B) Software

Set of instructions that tell the computer what to do.

Types of Software:

Type	Description	Examples
System Software	Controls hardware and system operations	Operating Systems, Device Drivers
Application Software	Performs specific user tasks	MS Word, Photoshop, Tally
Utility Software	Maintenance tools	Antivirus, Disk Cleanup
Programming Software	Used to develop applications	Compilers, Editors

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🔸 (C) Peopleware

The human users who operate and manage computers (like programmers, users, technicians).

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⚙️ 3. Functional Units of a Computer

🔹 Input Unit

Devices used to input data into the computer.

Examples: Keyboard, Mouse, Scanner, Microphone, Webcam.

🔹 Central Processing Unit (CPU)

Known as the brain of the computer.

Component	Function
ALU (Arithmetic Logic Unit)	Performs arithmetic and logical operations.
CU (Control Unit)	Controls flow of data and instructions.
Registers	Temporary storage for data being processed.

🔹 Memory / Storage Unit

Stores data, instructions, and results.

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💾 4. Memory / Storage Devices

🔹 Primary Memory (Main Memory)

Type	Description
RAM (Random Access Memory)	Temporary; volatile memory (data lost when power off).
ROM (Read Only Memory)	Permanent; non-volatile (stores BIOS).

Types of ROM: PROM, EPROM, EEPROM.

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🔹 Secondary Memory (External / Permanent Storage)

Used for long-term storage.

Examples: Hard Disk, SSD, CD/DVD, USB Drive, Memory Card.

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🔹 Cache Memory

• High-speed memory located between CPU and RAM.
• Stores frequently used instructions.
• Increases processing speed.

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🔹 Virtual Memory

• Portion of hard disk used as temporary RAM when physical RAM is full.

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🖥️ 5. Input and Output Devices

🔹 Input Devices

Devices that send data to the computer.

Examples:
Keyboard, Mouse, Scanner, Joystick, Barcode Reader, Microphone, Webcam, Touchscreen.

🔹 Output Devices

Devices that display or output processed data from the computer.

Examples:
Monitor, Printer, Speaker, Projector, Plotter.

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🧮 6. Types of Computers

Type	Description	Example
Microcomputer	Personal computers	Laptop, Desktop
Minicomputer	Multi-user system	IBM AS/400
Mainframe	Large-scale computing	IBM zSeries
Supercomputer	Extremely fast; used for scientific research	PARAM, Cray
Embedded Computer	Built into devices	ATM, Microwave, Smartwatch

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🧰 7. Classification by Generation

Generation	Period	Technology Used	Language	Example
1st	1940–56	Vacuum tubes	Machine Language	ENIAC, UNIVAC
2nd	1956–63	Transistors	Assembly Language	IBM 1401
3rd	1964–71	IC (Integrated Circuits)	High-Level Languages	IBM 360
4th	1971–80s	Microprocessors	C, BASIC	Apple II, IBM PC
5th	1980s–Present	AI, Parallel Processing	AI Languages	Robotics, AI Systems

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💻 8. Computer Software – Detailed

🔸 Operating System (OS)

Interface between user and hardware; manages all operations.

Functions of OS:

• File management
• Process management
• Memory management
• Device management
• Security

Examples: Windows, macOS, Linux, Android, iOS.

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🔸 Application Software

Performs specific tasks for users.
Examples: MS Office, Photoshop, VLC, Chrome.

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🔸 Programming Languages

Generation	Language Type	Example
1GL	Machine Language	Binary code (0,1)
2GL	Assembly Language	MOV, ADD
3GL	High-Level Language	C, BASIC, FORTRAN
4GL	Very High-Level	SQL, MATLAB
5GL	AI-based Languages	Prolog, LISP

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🌐 9. Computer Networks

🔹 Definition

A network is a collection of interconnected computers that share data and resources.

🔹 Types of Networks

Type	Full Form	Coverage
PAN	Personal Area Network	Small (1–10m) – Bluetooth
LAN	Local Area Network	Limited area – office/school
MAN	Metropolitan Area Network	City-level
WAN	Wide Area Network	Country/worldwide – Internet

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🔹 Network Devices

Device	Function
Modem	Converts digital signals to analog and vice versa.
Router	Routes data between networks.
Switch	Connects multiple computers within a LAN.
Hub	Basic device for connecting systems (no data filtering).
Gateway	Connects dissimilar networks.
Repeater	Amplifies signals to extend range.

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🔹 Network Topologies

• Bus – Single cable (used in small networks)
• Star – All devices connected to a central hub (most common)
• Ring – Circular data flow
• Mesh – Multiple interconnections (high reliability)

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🔐 10. Data and Information

Term	Definition
Data	Raw facts (e.g., numbers, names).
Information	Processed, meaningful data.

Data Processing Cycle:
👉 Input → Processing → Output → Storage → Feedback

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💡 11. Number Systems

System	Base	Digits Used	Example
Binary	2	0, 1	10101
Octal	8	0–7	345
Decimal	10	0–9	567
Hexadecimal	16	0–9, A–F	9AF

Conversions among these are common exam topics.

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🔢 12. Logic Gates (Basic Digital Logic)

Gate	Symbol	Function	Boolean Expression
AND	∧	Output 1 if both inputs 1	A·B
OR	∨	Output 1 if any input 1	A+B
NOT	¬	Inverts input	Ā
NAND	–	NOT of AND	(A·B)’
NOR	–	NOT of OR	(A+B)’
XOR	⊕	1 if inputs differ	A⊕B

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📡 13. The Internet and Web

🔹 Internet

• Global network connecting millions of computers.
• Invented by ARPANET (1969) in the USA.

🔹 Important Terms

Term	Description
URL	Uniform Resource Locator (web address)
HTTP/HTTPS	Web transfer protocols
IP Address	Unique number assigned to a device
DNS	Converts domain names to IP addresses
ISP	Internet Service Provider (e.g., Airtel, Jio)

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📧 14. Email & Cloud Computing

Concept	Description
Email	Electronic mail (uses SMTP/POP protocols).
Cloud Computing	Using remote servers to store & process data (e.g., Google Drive, AWS).
Benefits:	Scalability, accessibility, cost-effective.

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🔒 15. Cyber Security Basics

Term	Meaning
Virus	Malicious software that damages files.
Worm	Self-replicating malware.
Trojan Horse	Disguised harmful program.
Phishing	Fake emails/websites to steal data.
Firewall	Security barrier between networks.
Antivirus	Software to detect & remove malware.
Encryption	Converting data into coded form for security.

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🧮 16. Common Computer Acronyms

Acronym	Full Form
BIOS	Basic Input Output System
HTTP	HyperText Transfer Protocol
URL	Uniform Resource Locator
IP	Internet Protocol
CPU	Central Processing Unit
GUI	Graphical User Interface
HTML	HyperText Markup Language
USB	Universal Serial Bus
PDF	Portable Document Format
AI	Artificial Intelligence
IoT	Internet of Things
VPN	Virtual Private Network

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🏁 17. Emerging Technologies

Technology	Description
Artificial Intelligence (AI)	Machines that simulate human thinking.
Machine Learning (ML)	System learns from data automatically.
Internet of Things (IoT)	Interconnection of smart devices.
Blockchain	Secure, decentralized digital ledger.
Cloud Computing	On-demand computing services.
5G	Latest high-speed wireless technology.
Quantum Computing	Uses quantum bits (qubits) for ultra-fast processing.

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✅ Quick Summary

• Computer = Input → Process → Output → Storage → Feedback
• CPU = ALU + CU + Registers
• Memory Hierarchy: Cache → RAM → Hard Disk → Optical → Cloud
• Generations: Vacuum Tubes → Transistors → IC → Microprocessor → AI
• Networking: LAN, MAN, WAN
• Security: Virus, Firewall, Encryption