Best Revision Notes in Computer for Competitive Exams in 2025.

Best Revision Notes in Computer for Competitive Exams in 2025.

Computer and Terms associated with it

Here are some important one-liners drawn from the syllabus of NTPC(RRB) to help you revise key concepts in computer basics and applications for competitive exams:

General Concepts

• A computer is a machine performing processes, calculations, and operations based on instructions.
• A computer system includes both hardware and software components.
• Hardware refers to the physical equipment of a computer.
• Software comprises the operating systems and programs.
• The Information Processing Cycle includes Input, Processing, Storage, and Output.
• Input is the process of entering data into the computer.
• Processing involves the computer performing operations on the data.
• Output is the presentation of the result.
• Storage is saving data, programs, or results for future use.
• The CPU (Central Processing Unit) is considered the brain of the computer.
• The CPU performs all data processing operations and controls other parts of the computer.
• The Memory Unit stores instructions, data, and intermediate results.
• The Control Unit controls operations but does not process data.
• The ALU (Arithmetic Logic Unit) performs arithmetic and logic operations.
• The Input Unit allows users to enter data into the computer.
• The Output Unit allows users to get information from the computer.

Computer Generations

• First Generation (1942-1955) used Vacuum Tubes and Punch Cards.
• First Generation computers supported only machine language.
• Examples of First Generation computers include ENIAC and UNIVAC.
• Second Generation (1955-1964) used Transistors.
• The first operating system (Batch Processing, Multiprogramming) was developed in the Second Generation.
• Second Generation computers used Machine Language and Assembly language.
• Third Generation (1964-1975) used Integrated Circuits (ICs).
• Third Generation computers supported time-sharing OS and High Level Languages.
• Fourth Generation (1975-1980) used ICs with VLSI technology.
• The Fourth Generation saw the development of networks, the internet, GUIs, and the mouse.
• Examples of Fourth Generation computers include Apple II and CRAY supercomputers.
• Fifth Generation (1980-Present) uses ICs with ULSI and Nano technology.
• The Fifth Generation is characterized by the introduction of Artificial Intelligence and Expert Systems.

Input and Output Devices

• Input devices provide data and control signals to the computer.
• Examples of input devices include Keyboard, Mouse, Scanner, Joystick, Light Pen, Microphone.
• The Keyboard is a basic input device for entering data by pressing keys.
• The Mouse is a hand-held input device used to move the cursor.
• A Scanner converts pictures or text documents into a digital format.
• A Light Pen is an input device with a light-sensitive tip to point or select on screen.
• MICR (Magnetic Ink Character Recognition) is used in banks to read text printed with magnetic ink.
• OCR (Optical Character Reader) converts scanned text images into digital text.
• Bar Code Readers read bar coded data.
• OMR (Optical Mark Reader) recognizes marks made by pen or pencil.
• Output devices display the result of data processing.
• Examples of output devices include Monitors, Printers, Projectors.
• Monitors, also called Visual Display Units (VDU), are main output devices that form images from pixels.
• Types of monitors include CRT and Flat-Panel Display.
• A Printer produces hard copies of processed data.
• Printers are categorized into Impact and Non-impact types.
• A Projector projects output onto a large surface.

Computer Memory

• Memory is essential for computer tasks.
• Computer memory is categorized into Primary Memory and Secondary Memory.
• Primary memory is accessed first or directly by the processor.
• Primary memory includes RAM (Volatile) and ROM (Non-Volatile).
• RAM is volatile; it loses data when power is off.
• ROM is non-volatile; it retains data permanently from manufacture.
• Register Memory is the smallest and fastest memory, located in the CPU.
• Cache Memory is small but faster than main memory, holding frequently used data to speed up the system.
• Secondary memory devices are non-volatile and store data permanently.
• Secondary memory cannot be accessed directly by the CPU; data must first transfer to primary memory.
• Common secondary storage devices are Hard Disk and Optical Disks.
• Types of secondary storage: Solid state, Optical, Magnetic.
• Solid state storage stores data electrically and is faster than traditional hard drives.
• Optical storage (CD, DVD) uses a laser to read/write data.
• Magnetic storage (Hard disks) uses magnetic fields to store data.
• A Byte is a group of 8 bits.
• Kilobyte (KB) is 1024 Bytes, Megabyte (MB) is 1024 KB, Gigabyte (GB) is 1024 MB, Terabyte (TB) is 1024 GB.

Programming Languages

• Programming languages make the computer functional.
• Languages have vocabulary and rules known as syntax.
• Major language categories include Machine Language, Assembly Language, High Level Language.
• Machine Language is written for hardware and directly executed by the CPU.
• Assembly Language is a simpler, readable encoding of machine code.
• High Level Languages are similar to English and easy to understand (e.g., C, Python).

Computer Networks

• A computer network is a group of linked computers for communication and sharing.
• Network types by size: LAN, PAN, MAN, WAN.
• LAN (Local Area Network) connects computers in a small area like a building.
• PAN (Personal Area Network) is within an individual’s range, typically 10 meters.
• MAN (Metropolitan Area Network) interconnects LANs across a larger area.
• WAN (Wide Area Network) extends over a large geographical area like states or countries.
• The Internet is one of the biggest WANs.
• An Internetwork connects two or more computer networks using devices.

Logic Gates and Boolean Operations

• Logic Gates are basic building blocks of digital systems that produce binary signals.
• Basic logic gates include AND, OR, NOT, NAND, NOR, XOR, XNOR.
• A truth table represents the input-output binary variables for each gate.
• Boolean algebra deals with binary variables and logic operations (AND, OR, complement).

Computer Security

• Computer security protects systems from theft, damage, or disruption.
• Internet security focuses on attacks over the Internet.
• A cyber-attack exploits computer systems and networks using malicious code.
• Types of attacks include Web-based attacks and System-based attacks.
• Phishing attempts to steal sensitive information by masquerading as a trustworthy entity.
• Denial of Service (DoS) attacks make a server or network resource unavailable.
• A Virus is malicious software that replicates itself by modifying other programs.
• A Computer Worm is malicious, self-replicating software that spreads with no human intervention.
• A Trojan horse is malware that misleads users of its true intent, often spread via social engineering.
• Malware is malicious software used to disrupt operation, gather info, or gain access.
• Ransomware infects a system to extort money from its owner.
• Spyware is unwanted software that infiltrates devices, stealing data/info.
• Key logger malware stores all keystrokes.
• Anti-virus software is designed to prevent, detect, and remove malware.
• A Firewall monitors and controls network traffic based on security rules.
• Authentication confirms the truth of an identity.
• Authorization specifies access rights to resources.
• A Hacker gains illegal access to computers to get information or cause damage.
• Spam is unwanted emails.
• Encryption converts data into an encoded version readable only with a decryption key.

Important Abbreviations

• AI – Artificial Intelligence
• ASCII – American Standard Code for Information Interchange
• BIOS – Basic Input Output System
• CPU – Central Processing Unit
• DVD – Digital Video Disc/Digital Versatile Disc
• GUI – Graphical User Interface
• HTML – Hyper Text Markup Language
• HTTP – Hyper Text Transfer Protocol
• IP – Internet Protocol
• ISP – Internet Service Provider
• LAN – Local Area Network
• LCD – Liquid Crystal Display
• LED – Light Emitting Diode
• MB – Megabyte
• MHz – Megahertz
• OS – Operating System
• PDF – Portable Document Format
• RAM – Random Access Memory
• ROM – Read Only Memory
• SQL – Structured Query Language
• TCP/IP – Transmission Control Protocol/Internet Protocol
• URL – Uniform Resource Locator
• USB – Universal Serial Bus
• VGA – Video Graphics Array
• WAN – Wide Area Network
• WWW – World Wide Web

Fathers and Inventors

• Charles Babbage invented The Analytical Engine.
• Alan Turing invented The Turing Machine.
• Douglas Engelbart invented the Computer Mouse.
• Herman Hollerith invented the Keyboard.
• Dennis Ritchie invented the C programming language.
• James Gosling invented the Java programming language.
• Guido van Rossum invented the Python programming language.
• John Vincent Atanasoff & Clifford Berry invented the first fully electronic digital computer (ABC computer).

Applications of Computers

• Computers are widely used in Banking for transactions and ATMs.
• Computers are important in Insurance for managing client databases and policies.
• Computers play a vital role in Defence for missile control, communication, and operations.
• Computers help in Education through e-learning and administrative tasks.
• Computers are used in Desktop Publishing for creating documents.
• Computers are important in Healthcare for patient records and medical diagnosis.
• Computers are crucial for Communication via E-mail, video-conferencing, etc..
• Computers are used in Engineering Design for tasks like Computer-Aided Drafting (CAD).
• Computers are used for Entertainment, such as watching movies or playing games.
• Computers are important in Scientific Research across various fields.

These one-liners summarize key points from the source regarding computer basics, history, components, security, terminology, and applications, formatted for quick revision.