Computer Fundamentals

Introduction to Computer Systems

A Computer System is an integrated set of hardware and software designed to process data and produce meaningful information.

Functional Units of a Computer System

1. Input Unit - Receives data and instructions (e.g., mouse, keyboard).

2. Storage Unit - Stores data before, during, and after processing.

• Primary Storage: RAM, ROM

• Secondary Storage: HDD, SSD

3. Central Processing Unit (CPU) - Brain of the computer. (Components are explained later)

4. Output Unit - Displays the result (e.g., screen, printer).

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Computer Hardware & Software

Hardware: The physical, tangible components of a computer system.

• Input Devices: Keyboard, Mouse, Scanner, Microphone, Joystick.

• Output Devices: Monitor, Printer, Speakers, Projector.

• Processing Devices: Central Processing Unit (ALU, CU)

• Storage Devices: Primary(RAM, ROM), Secondary(HDD, SSD, USB Drive, Optical Discs (CD/DVD)

• Communication Devices: Enable data transfer between systems (Modem, NIC (Network Interface Card), Routers)

Software: The set of programs and instructions that direct hardware to perform specific tasks.

1. System Software

• Software that manages and controls computer's hardware and provides a platform for other software (application software) to run.

• Examples: Operating Systems (Windows, Linux, macOS)

2. Application Software

• Software that are designed to perform specific tasks directly for the end-user. Unlike system software, which manages the computer's internal operations, application software focuses on helping users accomplish particular activities.

• Examples: Microsoft Word (word processing), Photoshop (image editing), Browsers (Chrome, Firefox)

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CPU: ALU, Registers, CU

ALU

• Performs arithmetic and logical operations

Registers

• Small high speed storage area directly inside CPU that temporary hold’s data, instructions, and addresses during processing.

Control Unit

• Manages & co-ordinates all activities of the CPU,

• Generates control signals that direct operations.

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Memory & Storage Devices

Memory

Memory, often synonymous with RAM (Random Access Memory), is a temporary, high-speed storage area that the computer's Central Processing Unit (CPU) uses to store data and instructions that it needs to access immediately or frequently.

Types

Primary Memory

• RAM (Random Access Memory) – Temporary, used for running applications.

  • DRAM (Dynamic RAM)

  • SRAM (Static RAM)

• ROM (Read Only Memory) – Non-volatile, stores firmware.

  • PROM, EPROM, EEPROM

Cache Memory

• Small, high-speed memory close to CPU.

• Stores frequently accessed data/instructions.

Registers (Discussed above)

Storage Devices

Storage devices are hardware components used for long-term, non-volatile retention of digital data. They store files, applications, and the operating system permanently, even when the computer is turned off.

Types of Storage Devices

1. Magnetic Storage

• Data stored magnetically.

• Examples: Hard Disk Drive (HDD), magnetic tapes.

2. Solid-State Storage

• No moving parts, faster than magnetic.

• Examples: SSD, memory cards, USB flash drives.

3. Optical Storage

• Data is written and read using a laser (light).

• Examples: CD, DVD, Blu-ray Discs

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Operating System & Application programs

Operating System

An Operating System is system software that acts as an interface between the user and the computer hardware. It manages hardware, software resources, and provides common services for computer programs.

Examples: Windows, macOS, Linux.

Application Programs (Apps)

Software that are designed to perform specific tasks directly for the end-user. Unlike system software, which manages the computer's internal operations, application software focuses on helping users accomplish particular activities.

Examples: Microsoft Word, Google Chrome, Adobe Photoshop.

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Computer virus & remedies

Computer Virus

A computer virus is a type of malicious software (malware) designed to spread from one computer to another and interfere with normal system operations.

Types of Computer Viruses

1. File Infector Virus

   • Attaches itself to executable files (.exe, .com).

   • Activates when the file runs.

2. Boot Sector Virus

   • Infects the master boot record (MBR) of storage devices.

   • Loads before the operating system starts.

3. Worm

   • Self-replicates and spreads through networks.

   • Consumes bandwidth and system resources.

4. Trojan Horse

   • Appears to be useful software but hides malicious code.

   • Doesn't replicate but opens backdoors.

5. Ransomware

   • Encrypts user files or locks the system.

   • Demands payment to restore access.

6. Polymorphic Virus

   • Changes its code every time it runs.

   • Difficult for antivirus programs to detect.

Remedies and Prevention

1. Install and Update Antivirus Software

   • Use trusted software like Windows Defender, Avast, Norton, etc.

   • Regularly update virus definitions.

2. Keep Software Updated

   • Regularly update your OS and all installed applications to patch security holes.

3. Avoid Suspicious Links & Attachments

   • Don’t open emails or download files from unknown sources.

4. Use a Firewall

   • Helps block unauthorized access to your system.

5. Enable Real-Time Protection

   • Most antivirus programs offer this to detect threats instantly.

6. Use Strong Passwords

   • Protects against unauthorized access to your data.

7. Be Cautious with Public Wi-Fi

   • Avoid accessing sensitive information on public networks.

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Word Processor, Spreadsheet & PowerPoint

Word Processor

A word processor is an application program used for creating, editing, formatting, and printing text-based documents.

Examples: Microsoft Word, Google Docs, LibreOffice Writer

Common Uses: Writing reports, letters, essays, resumes

Spreadsheet

A spreadsheet is an application used to organize, analyze, and store data in tabular form, especially numbers.

Examples: Microsoft Excel, Google Sheets.

Common Uses: Budgeting, accounting, data analysis, attendance tracking

PowerPoint (Presentation Software)

PowerPoint is a presentation program used to create slideshow presentations with text, images, animations, and multimedia.

Examples: Microsoft PowerPoint, Google Slides, LibreOffice Impress

Common Uses: Business presentations, educational lectures, project reports

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Computer System Configuration

Computer System Configuration refers to the detailed description of the components and settings that make up a computer system. It includes both hardware and software specifications that determine the system's performance and capabilities.

Hardware Configuration

These are the physical components of a computer.

Software Configuration

These are the programs and system settings that control how the computer operates.

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Fonts, Nepali Fonts, Unicode and Unicode Fonts

Font

A font is a style or design for text. It determines how letters, numbers, and symbols look when you type. Example fonts: Arial, Times New Roman, Calibri, etc.

Nepali Fonts

Nepali fonts are fonts that are used to write in Nepali language (Devanagari script).

There are two main types:

Unicode

Unicode is a universal system that assigns a unique number (code point) to every character in every language.

• For example:

  • The letter "क" = U+0915 in Unicode

  • This makes Nepali text usable across all platforms, searchable, and compatible with modern devices.

Unicode Fonts

Unicode fonts are fonts that follow the Unicode standard and display characters based on their code points.