04/06/2026
Lesson 1-
Introduction to computer system
Data and Information
Data is raw. Unorganized facts. Needs to organize or process.
Example:
Mathematics marks of the class.
Information
Informations are organized facts. It is processedsystem
Example: Average mathematic mark of the class.
Features of informations
✔️Reliability
✔️Accessibility
✔️Accuracy
✔️Relevance
✔️Completeness
Features of a computer. 🖥️💻📱📲📠
✔️Speed
✔️Accuracy
✔️Versatility
✔️Diligence
✔️Multitasking
Types of computers
✅Super computer
✅Mainframes
✅Mini frames
✅Micro computer( personal computer)
✅Workstations
✅Servers
Examples for Micro computers
✴️Laptop
✴️Desktop
✴️Tablets
✴️Palmtop
✴️Smartphone
Software
✔️Software is a collection of instructions, data, or programs that tell a computer how to work.
✔️ It is the non-physical (intangible) part of a computer system that enables hardware to perform tasks.
Software is mainly divided into two categories:
✅System software
✅Application software
System Software/ OS
This type of software controls and manages the hardware of the computer and provides a platform for application software to run.
Operating System (OS)
• The OS acts as an interface between the user and the computer hardware. Examples of Operating Systems:
• Windows (e.g., Windows 10, Windows 11)
• Linux (e.g., Ubuntu, Fedora)
• macOS
• Android
• iOS
Functions of an Operating System (OS)
• Process Management
• Memory Management
• File Management
• Device Management (I/O Management.
• User Interface (UI)
• Security and Access Control
• Networking Management
• Error Detection and Handling
Free and Open Source Software (FOSS)
FOSS is software that is both free to use and open source, meaning its source code is available for anyone to view, modify, and distribute.
Key Features:
• Free of cost or minimal cost.
• Source code is open and accessible.
• Users can modify, improve, and share it.
• Community-driven development. Examples: Linux, LibreOffice, Mozilla Firefox, GIMP, Apache.
Server Software
Server software is a type of software that enables a computer (server) to provide services, data, or resources to other computers (clients) over a network.
Functions:
• Manages network resources and data sharing.
• Handles client requests and delivers responses.
• Provides centralized storage, security, and backup.
• Supports multiple users simultaneously.
• Examples:
• Web Server: Apache, Nginx, Microsoft IIS
• Database Server: MySQL, Oracle, PostgreSQL
• Mail Server: Microsoft Exchange, Postfix
• File Server: Samba, Windows Server File Services
Application Software
This type of software is designed to help users perform specific tasks or application
Examples of Application Software:
• Microsoft Word, Excel, PowerPoint (productivity software/package software)
• Google Chrome, Mozilla Firefox (web browsers)
• VLC Media Player (multimedia software)
• Adobe Photoshop (graphics software)
• WhatsApp, Zoom (communication software)
• Pay Role (Custermized software)
Computer Memory
Computer memory is the storage space in a computer where data and instructions are kept for processing.
It is essential for the computer to perform tasks.
Types of Memory
Primary Memory (Volatile)
✅RAM (Random Access Memory): Stores data temporarily while the computer is working. Data is lost when power is off.
Types of RAM
1. SRAM (Static RAM)
Stores data using flip-flops.
Faster and more expensive.
Used in cache memory.
2. DRAM (Dynamic RAM)
Stores data in capacitors, needs constant refreshing.
Slower but cheaper and higher capacity.
Used in main memory.
3. SDRAM (Synchronous DRAM)
Works in sync with the CPU clock.
Faster than regular DRAM.
4. DDR SDRAM (Double Data Rate SDRAM)
Transfers data on both rising and falling edges of the clock.
Versions: DDR, DDR2, DDR3, DDR4, DDR5 (increasing speed and efficiency).
5. VRAM (Video RAM)
Special RAM for graphics cards.
Improves video and image rendering.
6. NVRAM (Non-Volatile RAM)
Retains data even when power is off.
Example: Flash memory, CMOS
Differences between SRAM and DRAM
SRAM = Fast, expensive, small capacity → Used in cache.
DRAM = Slower, cheaper, large capacity → Used in main memory
✅Cache Memory: High-speed memory that stores frequently used instructions for quick access. short
term use. Volatile memory.
✅ROM (Read Only Memory):
• Non-volatile memory that stores permanent instructions like BIOS.
Importance:
• Holds programs and data for processing.
• Improves speed and efficiency.
• Helps store information permanently or temporarily.
✅Register Memory
Registers are the fastest memory in a computer, located inside the CPU.
They store small amounts of data and instructions that the processor is currently using.
Very small (measured in bytes or words, e.g., 32-bit or 64-bit registers).
Faster than cache, RAM, and other types of memory because they are directly connected to the processor.
Registers are volatile (data is lost when power is off).
Secondary Memory (Non-Volatile)
• Examples: Hard Disk, SSD, CD, DVD, USB drives.
• Stores data permanently for longtime use
Differences between HDD (Hard Disk Drive) and SSD (Solid State Drive)
HDD - Cheaper, high storage, slower, mechanical.
SSD - Faster, durable, quieter, but costlier.
Firewall
A firewall is a network security system .
It acts as a protective barrier between a trusted internal network and untrusted external networks such as the Internet.
Functions:
• Blocks unauthorized access
• Allows legitimate communication
• Protects against cyber threats (viruses, hackers, malware)
• Monitors network traffic and maintains security policies. Types:
• Hardware Firewall – physical device used mainly in networks
• Software Firewall – installed on computers or servers
• Cloud/Network Firewalls – modern online protection systems
Utility Program
A utility program is a type of system software that helps manage, maintain, and control computer resources. It performs specific tasks to keep the computer system running efficiently.
Examples:
• Antivirus software – protects the computer from viruses.
• File management tools – help organize and manage files and folders.
• Backup software – creates copies of important data.
• Disk cleanup tools – remove unnecessary files to free up space.
Main Purpose:
To improve the performance, security, and usability of a computer system.
BIOS System
BIOS stands for Basic Input/Output System.
It is a firmware stored on a chip on the computer’s motherboard that starts automatically when the computer is powered on.
Main Functions:
• Performs POST (Power-On Self-Test):
Checks hardware components like RAM, keyboard, and disk drives to ensure they work properly.
• Loads the Operating System:
Finds and loads the operating system from the hard drive into memory.
• Provides Hardware Control:
Manages basic communication between the operating system and computer hardware.
• Offers Setup Utility:
Allows users to configure hardware settings like boot order, date, and time.
G. P. O. B. Prera
Lecturer in ICT
