FUNDAMENTAL OF COMPUTER

COMPUTER FUNDAMENTALS

Computer

A computer is an electronic device that performs arithmetic and logical operations.

• Arithmetic operations include addition, subtraction, multiplication, and division.
• Logical operations include AND, OR, and NOT.

A computer:

• Accepts input from the user
• Processes the input
• Produces output as a result

Computers are widely used in communication and have played a major role in the development of Information Technology.

Characteristics of a Computer

The main characteristics of a computer are:

1. Speed

• A computer works at very high speed.
• It can execute millions of instructions per second.
• Speed is measured in Hertz (Hz) such as:
  • KHz (Kilohertz)
  • MHz (Megahertz)
  • GHz (Gigahertz)
• Modern computers perform calculations in nanoseconds.

2. Accuracy

• A computer is an accurate machine.
• It performs calculations correctly if the input data is correct.
• Errors usually occur due to wrong input, not because of the computer.

3. Reliability

• A computer is reliable.
• It performs tasks exactly according to given instructions.
• It can work continuously without failure.

4. Versatility

• A computer is versatile, meaning it can perform different types of tasks.
  Examples:
• Text processing
• Graphics
• Sound
• Animation
• Calculations

5. Storage Capacity

• A computer has a large memory capacity.
• It can store huge amounts of data in a small space.
• The basic unit of storage is Byte.

6. Diligence

• A computer does not get tired.
• It can work continuously for long hours without losing accuracy.

7. Logical Ability

• A computer can compare data such as:
  • Numbers
  • Text
• It makes logical decisions based on instructions.

8. Flexibility

• A computer can perform multiple tasks at the same time.
• It can switch between applications instantly.

9. Transfer of Data

• Data can be easily transferred from one computer to another using networks or storage devices.

Limitations of Computer

Despite many advantages, computers also have limitations:

• A computer has zero intelligence (IQ).
• It cannot think or make decisions on its own.
• It works only according to instructions given by the user.
• A computer has no emotions or feelings.
• It cannot learn from past experiences unless programmed (AI systems are exceptions).

CPU (Central Processing Unit)

The CPU is known as the brain of the computer.

• All processing of data happens inside the CPU.
• It converts raw data into meaningful information.
• It is both a hardware component and an important functional unit.

Functional Components of CPU

The CPU consists of three main components:

1. MU — Memory Unit
2. CU — Control Unit
3. ALU — Arithmetic Logic Unit

Control Unit (CU)

The Control Unit controls the working of all computer components.

Functions:

• Coordinates all hardware devices
• Controls the flow of data and instructions
• Performs operations in the Fetch–Decode–Execute–Store (F-D-E-S) cycle

Steps:

1. Fetch instructions from memory
2. Decode instructions
3. Send instructions to ALU
4. Execute instructions
5. Store results

Arithmetic Logic Unit (ALU)

The ALU performs:

Arithmetic Operations

• Addition (+)
• Subtraction (-)
• Multiplication (×)
• Division (÷)

Logical Operations

• Greater than (>)
• Less than (<)
• Equal to (=)
• Not equal to (!=)

The ALU processes data and sends the result back to the Control Unit.

Memory Unit (MU)

The Memory Unit stores:

• Data
• Instructions
• Intermediate results
• Final results

Key Points:

• Data is stored before processing
• Each memory location has a unique address
• High-speed memory inside CPU is called Registers

Computer Buses

Computer components are connected using buses:

INPUT DEVICES

Input Device

An input device is a hardware device used to enter data and instructions into a computer.

Input devices allow users to communicate with the computer system.

Examples of Input Devices:

• Keyboard
• Mouse
• Joystick
• Scanner
• Microphone
• Webcam
• Barcode Reader
• Biometric Sensor

Types of Input Devices

1. Keyboard

A keyboard is the most commonly used input device.

Functions:

• Used to type text
• Used to enter commands and instructions
• Sends input data to the computer

Features:

• A standard keyboard has 101 to 106 keys
• Keys include:
  • Alphabet keys
  • Number keys
  • Function keys
  • Special keys

Types of Keyboards:

• QWERTY — Most commonly used
• AZERTY — Used mainly in France
• QWERTZ — Used in Germany and Central Europe
• DVORAK — Designed for faster typing

Note:
Keys are buttons that represent letters, numbers, and symbols.

2. Mouse

A mouse is a handheld pointing device.

Functions:

• Moves pointer on screen
• Selects items
• Opens programs
• Scrolls pages

Features:

• Usually has:
  • Two buttons
  • One scroll wheel

3. Joystick

A joystick is an input device used mainly for playing games.

Features:

• Similar to a mouse
• Controls movement on screen
• Used in gaming and simulation software

4. Scanner

A scanner is an input device that converts printed documents into digital format.

Functions:

• Captures images or text
• Stores scanned data inside the computer

Types of Scanner:

• Handheld Scanner
• Flatbed Scanner

5. OMR (Optical Mark Reader)

OMR stands for Optical Mark Reader.

Functions:

• Detects marked answers on paper
• Used to read shaded areas

Common Uses:

• OMR answer sheets
• Surveys
• Exams

6. OCR (Optical Character Reader)

OCR stands for Optical Character Reader.

Functions:

• Reads printed text
• Converts printed text into editable digital text

Common Uses:

• Reading printed documents
• Form verification
• Digitizing books

7. MICR (Magnetic Ink Character Reader)

MICR stands for Magnetic Ink Character Reader.

Functions:

• Reads characters printed with magnetic ink

Common Uses:

• Used by banks
• Processing cheques

8. Light Pen

A light pen is a pen-shaped input device.

Functions:

• Used to draw on the screen
• Select objects directly on display

Features:

• Contains light-sensitive detector

9. Barcode Reader

A barcode reader is a scanning device used to read barcodes.

Features:

• Reads vertical black bars
• Converts barcode into digital data

Common Uses:

• Supermarkets
• Billing systems
• Inventory management

10. Microphone

A microphone is a voice input device.

Functions:

• Records sound
• Converts sound into digital signals

Common Uses:

• Voice recording
• Video calls
• Online meetings

11. Digital Camera

A digital camera captures images and stores them digitally.

Features:

• Saves images in memory card
• Quality measured in pixels

Common Uses:

• Photography
• Video recording

12. Webcam (Web Camera)

A webcam is a video camera connected to a computer.

Functions:

• Sends live video to computer
• Used for video communication

Common Uses:

• Video conferencing
• Online classes
• Video calls

13. Biometric Sensor

A biometric sensor captures unique biological information.

Examples:

• Fingerprint scanner
• Iris scanner
• Face recognition

Common Uses:

• Security systems
• Attendance systems
• Mobile unlocking

List of Input Device and Their Use

OUTPUT DEVICE

Output Device

An output device is a hardware device that displays or produces the result after processing data.

The user receives processed results through output devices.

Output can be in two forms:

• Soft Copy — Displayed on screen
• Hard Copy — Printed on paper

Common Output Devices:

1. Printer
2. Plotter
3. Monitor
4. Speaker

1. Printer

A printer is an output device used to produce hard copies of documents on paper.

Printer Characteristics:

Printers are classified based on:

1. Quality of Printing

• Measured in DPI (Dots Per Inch)
• Higher DPI means better quality

2. Speed

Measured in:

• CPS — Characters Per Second
• PPM — Pages Per Minute

3. Printing Mechanism

How the printer prints on paper.

Types of Printers

Printers are mainly classified into:

1. Impact Printer
2. Non-Impact Printer

Impact Printer

An impact printer prints by striking the print head against an ink ribbon.

Features:

• Produces noise
• Uses ribbon
• Suitable for bulk printing

Types of Impact Printer:

1. Line Printer
2. Character Printer

Line Printer

A line printer prints one line at a time.

Features:

• Very fast printing
• Used in large organizations

Speed:

• 300 to 3000 lines per minute

Types:

1. Drum Printer
2. Chain Printer

Drum Printer

A drum printer uses a rotating cylindrical drum.

Features:

• Characters are embossed on drum
• Hammer strikes ribbon to print characters
• Speed: 300 to 2000 lines per minute

Chain Printer

A chain printer uses a fast rotating chain.

Features:

• Characters are printed using rotating chain
• Speed: 40 to 2500 lines per minute

Character Printer

A character printer prints one character at a time.

Also known as serial printer.

Types:

1. Daisy Wheel Printer
2. Dot Matrix Printer

Daisy Wheel Printer

A daisy wheel printer has a wheel shaped like a flower.

Features:

• High-quality printing
• Slow speed
• Cannot print graphics

Speed:

• 10 to 50 characters per second

Dot Matrix Printer

A dot matrix printer prints characters using pins.

Features:

• Uses ribbon
• Low printing cost
• Suitable for continuous paper

Specifications:

• Uses 9 or 24 pins
• Speed: 100 to 300 characters per second
• Resolution: 150 to 250 DPI

Non-Impact Printer

A non-impact printer prints without striking the ribbon.

Features:

• Faster than impact printers
• Less noise
• Better print quality
• Can print colored output

Types:

1. Inkjet Printer
2. Laser Printer

Inkjet Printer

An inkjet printer sprays tiny droplets of ink onto paper.

Features:

• Produces high-quality images
• Suitable for photo printing

Speed:

• 2 to 10 pages per minute

Resolution:

• 400 to 4000 DPI

Laser Printer

A laser printer uses laser technology to print.

Features:

• Fast printing
• High-quality output
• Works like a photocopy machine

Speed:

• 12 to 25 pages per minute

Resolution:

• 600 to 2400 DPI

2. Speaker

A speaker is an output device that converts electrical signals into sound.

Features:

• Produces audio output
• Used for music, video, and alerts

Speakers can be:

• Internal — Built inside computer
• External — Connected through audio jack

Sound quality depends on frequency.

3. Plotter

A plotter is an output device used to produce large-size graphics.

Uses:

• Engineering drawings
• Maps
• Charts
• CAD designs

Plotters use electronic pens to draw images.

Types of Plotters

1. Flatbed Plotter
2. Drum Plotter
3. Micrographic Plotter
4. Inkjet Plotter

Flatbed Plotter

A flatbed plotter uses a flat surface.

Features:

• Paper remains fixed
• Pen moves horizontally and vertically

Drum Plotter

A drum plotter uses a rotating drum.

Features:

• Paper rotates around drum
• Pen moves across drum

Micrographic Plotter

In this type:

• Paper moves back and forth
• Held by pinch wheels

Inkjet Plotter

An inkjet plotter uses ink spray instead of pens.

Features:

• Produces colored drawings
• Used for banners and posters

4. Monitor

A monitor is an output device that displays soft copy output.

It is also called:

VDU — Visual Display Unit

Functions:

• Displays processed data
• Shows images, text, and videos

Monitors connect to:

• Video card
• Motherboard

Types of Monitor

1. CRT Monitor
2. LCD Monitor
3. LED Monitor

CRT Monitor

(Cathode Ray Tube)

Features:

• Uses vacuum tube
• Bulky and heavy
• Consumes more power

Older technology.

LCD Monitor

(Liquid Crystal Display)

Features:

• Thin and lightweight
• Produces sharper images
• Uses TFT technology

Common in laptops and desktops.

LED Monitor

(Light Emitting Diode)

Features:

• Very thin
• High brightness
• Energy efficient
• Better image quality

Most widely used today.

Special Display Device

Touch Screen

A touch screen acts as:

• Input device
• Output device

Uses:

• ATMs
• Airports
• Railway stations
• Information kiosks

List of OutPut Device and their Use

STORAGE DEVICES

Storage Devices

Storage devices are hardware components used to store data, information, and instructions either temporarily or permanently.

Storage devices are mainly classified into two types:

1. Primary Storage Devices
2. Secondary Storage Devices

Primary Storage Devices (Main Memory)

Primary storage devices store data temporarily while the computer is working. These devices are fast but have limited storage capacity.

Types of Primary Memory

1. RAM (Random Access Memory)

• RAM is a temporary memory.
• Data stored in RAM is lost when the computer is turned off.
• It is used to store data and instructions currently being processed.
• RAM is also called volatile memory.

2. ROM (Read Only Memory)

• ROM is a permanent memory.
• Data stored in ROM remains even when the computer is turned off.
• It stores important instructions required to start the computer.
• ROM is also called non-volatile memory.

Secondary Storage Devices (Auxiliary Memory)

Secondary storage devices store data permanently. These devices have large storage capacity and are used to save data for long-term use.

Features of Secondary Storage

• Stores data permanently
• Large storage capacity
• Data is not lost when power is off
• Used for backup and recovery
• Slower than primary memory

Types of Secondary Storage Devices

1. Magnetic Storage Devices

Magnetic storage devices store data using magnetic material.

Hard Disk

• A hard disk is the most commonly used storage device.
• It stores large amounts of data permanently.
• It consists of circular plates called platters.
• Data is stored in the form of magnetic spots.
• Hard disks are used as internal storage in computers.
• Storage capacity examples:
  • 500 GB
  • 1 TB
  • 2 TB or more

Floppy Disk (Older Technology)

• A floppy disk is a portable magnetic storage device.
• Size: 3.5 inches
• Storage capacity: 1.44 MB
• It is rarely used today.

2. Optical Storage Devices

Optical storage devices use laser light to read and write data.

CD (Compact Disc)

• CD stands for Compact Disc.
• It is made of lightweight plastic.
• Storage capacity: Up to 700 MB
• Used to store music, videos, and data.

DVD (Digital Versatile Disc)

• DVD stands for Digital Versatile Disc.
• Looks similar to a CD but stores more data.
• Storage capacity: Up to 4.7 GB to 15 GB
• Used to store movies and large files.

Blu-ray Disc

• Blu-ray Disc stores very large amounts of data.
• Storage capacity:
  • 25 GB (single layer)
  • 50 GB (dual layer)
• Uses a blue-violet laser.
• Used for high-definition videos.

3. Flash Storage Devices

Flash storage devices are small, fast, and portable.

Pen Drive (USB Flash Drive)

• A pen drive is a small portable storage device.
• Connected using a USB port.
• Rewritable and easy to carry.
• Storage capacity examples:
  • 16 GB
  • 32 GB
  • 64 GB
  • 128 GB or more

Memory Card

• A memory card is used in mobile phones, cameras, and tablets.
• Types include:
  • SD Card
  • MicroSD Card
• Storage capacity ranges from:
  • 1 GB to 2 TB

Units of Storage

Data in computers is measured using storage units.

Summary

• Storage devices store data and information.
• Primary storage includes RAM and ROM.
• Secondary storage includes hard disks, CDs, DVDs, pen drives, and memory cards.
• Flash storage devices are commonly used today due to their speed and portability.
• Storage capacity is measured in units like Byte, KB, MB, GB, and TB.

SOFTWARE

Program

A program is a set of meaningful instructions that performs a specific task.

Software

Software is a collection of programs developed to perform specific tasks.

• Software is an intangible part of a computer.
• It provides instructions that tell the computer what to do.

Types of Software

Software is mainly divided into three categories:

1. Application Software
2. System Software
3. Utility Software

APPLICATION SOFTWARE

Application software refers to programs designed to perform specific tasks for users.

• It is created to meet the specific needs of users.

Types of Application Software

1. Application Package
2. Customized Package

1. Application Package

An application package is designed to perform common tasks required by many users.

Examples:

• Word processing software
• Spreadsheet software
• Presentation software

2. Customized Package

Customized software is developed for a specific user or organization.

• It is also called tailor-made software.
• It is developed according to user requirements.

Examples:

• Inventory management system
• Fee collection system
• Hospital management system

SYSTEM SOFTWARE

System software helps the user operate and communicate with the computer system.

• It controls computer hardware.
• It manages system operations.
• It acts as an interface between user and hardware.

Types of System Software

1. Operating System
2. Language Processor

1. OPERATING SYSTEM

An Operating System (OS) is system software that acts as an interface between the user and computer hardware.

Functions of Operating System

• Manages hardware resources
• Controls system operations
• Runs application programs
• Shares computer resources

EXAMPLES OF APPLICATION SYSTEMS

Accounting Management System

An Accounting Management System is used to manage financial records.

• Helps maintain accounts
• Reduces data redundancy
• Generates reports such as:
  • Profit and Loss Account
  • Balance Sheet

Reservation System

A Reservation System is used to book tickets, hotel rooms, and other services.

• Allows online booking
• Shows availability of seats
• Stores booking details

Human Resource (HR) Management System

An HR Management System manages employee information.

• Stores employee records
• Handles salary processing
• Manages performance records
• Maintains payroll data

Note:
NFC (Near Field Communication) cards are used for attendance in schools, universities, and offices.

UTILITY SOFTWARE

Utility software consists of small programs that help manage and maintain computer systems.

• It supports system operations.
• It performs additional maintenance tasks.

Examples of Utility Software

1. Disk Defragmenter
2. Disk Checker
3. Disk Cleaner
4. Disk Partitioner
5. Backup Utility
6. Disk Compression Tool
7. File Manager

FIRMWARE

Firmware is a small program stored in ROM.

It performs basic tasks such as:

• Booting the computer
• Keeping system time

VIRUS SCANNER / CLEANER

A virus scanner detects and removes harmful software (malware) from a computer.

• Scans storage devices
• Removes viruses
• Protects system data

ENCRYPTION AND DECRYPTION

Encryption

Encryption is the process of converting data into a secret code.

• Protects confidential data
• Prevents unauthorized access

Encrypted data is called cipher text.

Decryption

Decryption is the process of converting encrypted data back into its original form.

• Allows authorized users to access data

Examples of Encryption Tools:

• OpenSSL
• Stunnel
• OpenVPN

OPERATING SYSTEM TYPES

UNIX Operating System

UNIX is one of the earliest operating systems.

• Developed in 1969 at AT&T Bell Labs
• Initially written in Assembly language
• Later rewritten in C language
• Supports:
  • Multi-user system
  • Multitasking

Used in:

• Servers
• Workstations
• Universities

SOLARIS Operating System

Solaris is a UNIX-based operating system.

• Developed by Sun Microsystems
• Now known as Oracle Solaris
• Supports multiprocessing

WINDOWS Operating System

Windows is a popular graphical operating system.

• Developed in 1985
• Easy to use with graphical interface

Examples:

• Windows 95
• Windows 98
• Windows NT
• Windows 2000

FEATURES OF OPERATING SYSTEM

1. User-friendly interface
2. Supports multitasking
3. Provides GUI (Graphical User Interface)
4. Supports networking
5. Supports multimedia applications

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OPERATING SYSTEM

Operating System Definition

An Operating System coordinates hardware, software, and user resources.

• Provides interface between hardware and software
• Ensures efficient system performance

COMPONENTS OF OPERATING SYSTEM

1. Control Program
2. Supervisory Program
3. Service Program

Control Program

• Manages hardware resources
• Allocates memory
• Controls CPU activities
• Handles input and output operations

Supervisory Program

• Controls operating system functions
• Manages application programs

Service Program

Provides services to users such as:

• Saving files
• Loading data
• Deleting files

CLASSIFICATION OF OPERATING SYSTEM

Based on Interface

1. CUI (Character User Interface)

• Commands are typed using keyboard
• Works through command prompt

Examples:

• PC-DOS
• MS-DOS
• UNIX

2. GUI (Graphical User Interface)

• Uses icons, menus, and buttons
• Easy to operate

Examples:

• Windows 7
• Windows 8

Based on Number of Users

1. Single User Operating System

Allows only one user at a time.

Example:

• MS-DOS

2. Multi-User Operating System

Allows multiple users at the same time.

Examples:

• Linux
• UNIX