Bhashi Technology Advisor

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

ICT (තොරතුරු හා සන්නිවේදන තාක්ෂණය) සම්බන්ධ ප්‍රධාන ගැටලු ....

ICT වාසි බොහොමයක් තිබුණත්, එයට සම්බන්ධ ගැටලුත් ඇත.
✔️සෞඛ්‍ය ගැටලු
✔️ඩිජිටල් විභේදනය
✔️කම්පියුටර් අපරාධ
✔️කුසලතා අහිමිවීම

🧠 1. සෞඛ්‍ය ගැටලු (Health Issues)
ICT උපාංග දිගු කාලයක් භාවිතා කිරීමෙන් අපගේ සෞඛ්‍යයට අහිතකර බලපෑම් ඇතිවිය හැක.
සාමාන්‍ය සෞඛ්‍ය ගැටලු:
ඇස් වේදනාව (Eye strain) – තිරයට දිගු වේලාවක් නිරාවරනය වීමෙන් ඇස් වියළීම හෝ වේදනාව
පිට හා බෙල්ලේ වේදනාව – වැරදි ඉරියව් නිසා
පුනරාවර්තන ආතති ආබාධ (RSI) – ටයිප් කිරීම වැනි වැඩ නැවත නැවත කිරීමෙන් අත, ඇඟිලි හෝ මැණික් කටුවේ වේදනාව

අඩික්ශන් (Addiction) – කම්පියුටර් හෝ දුරකථන වැඩිපුර භාවිතා කිරීම
🌍 2. ඩිජිටල් විභේදනය (Digital Divide)
ඩිජිටල් විභේදනය කියන්නේ ICT භාවිතයට අවශ්‍ය සම්පත් ඇති පුද්ගලයින් හා එවැනි අවස්ථා නොමැති පුද්ගලයින් අතර ඇති පරතරයයි.
උදාහරණ:
සමහර සිසුන්ට කම්පියුටර් සහ අන්තර්ජාලය තිබුණත්, වෙනත් සිසුන්ට නැත
ගම්මාන ප්‍රදේශවල අන්තර්ජාල පහසුකම් සීමිත වීම
දුප්පත් පවුල්වලට නව තාක්ෂණය මිලදී ගැනීමට නොහැකි වීම

මෙය අධ්‍යාපනය හා අවස්ථා වල අසමානතාවයක් ඇති කරයි.
🔐 3. කම්පියුටර් අපරාධ (Computer Crimes)
කම්පියුටර් අපරාධ (Cybercrime) කියන්නේ කම්පියුටර් හෝ අන්තර්ජාලය භාවිතා කර සිදු කරන නීතිවිරෝධී ක්‍රියාය.
උදාහරණ:
හැකින් (Hacking) – කම්පියුටර් පද්ධති වලට අනවසරයෙන් ඇතුල් වීම
ෆිෂිං (Phishing) – පුද්ගලික තොරතුරු ලබාගැනීමට වංචා කිරීම
අයිඩෙන්ටිටි හොරකම (Identity theft) – පුද්ගලික දත්ත සොරකම් කිරීම
වයිරස්/මැල්වෙයාර් පැතිරවීම
👉මෙවැනි අපරාධවලින් මුදල්, දත්ත සහ පුද්ගලිකත්වයට හානි විය හැක.
⚙️ 4. කුසලතා අහිමිවීම (Deskilling)
කුසලතා අහිමිවීම කියන්නේ යන්ත්‍ර හෝ කම්පියුටර් වැඩ කිරීම නිසා මිනිසුන්ගේ කුසලතා අඩුවීමයි.
උදාහරණ:
ගණිත ගැටලු සඳහා කැල්කියුලේටරය භාවිතා කිරීම
GPS භාවිතයෙන් මාර්ග හඳුනා ගැනීම
කර්මාන්තශාලාවල යන්ත්‍ර මිනිසුන්ගේ රැකියා මාරු කිරීම
මෙය මිනිසුන්ගේ හැකියාවන් හා රැකියා අවස්ථා අඩු කරයි.

Ransomware ....
Ransomware is a type of malicious software (malware) that blocks access to a computer system or encrypts files, and then demands money (a ransom) to restore access.

How it works:
A user unknowingly downloads ransomware (often through email attachments, fake websites, or infected software).
The ransomware locks files or the entire system.
A message appears demanding payment (usually in cryptocurrency).
Even if the ransom is paid, there is no guarantee the data will be recovered.

Examples of ransomware:
WannaCry ransomware attack – spread worldwide and affected hospitals and businesses.
Petya ransomware – encrypted entire systems instead of just files.

How to protect yourself:
Do not open suspicious emails or links.
Keep your software updated.
Use antivirus software.
Regularly back up important data.

Phishing ......

Phishing is a cyber attack where criminals pretend to be trustworthy organizations (like banks, social media platforms, or companies) to trick people into giving sensitive information such as usernames, passwords, or credit card details. They usually use emails, text messages, or fake websites that look real to deceive users.
Common Types with Examples

Email Phishing

You receive an email that looks like it is from your bank saying:
“Your account has been suspended. Click here to verify your details.”
The link takes you to a fake website where your information is stolen.

SMS Phishing (Smishing)

A message says:
“You have won a prize! Click this link to claim now.”
When you click the link, it may ask for personal details or install harmful software.
Website Phishing
You visit a website that looks exactly like a real site (like Facebook or a bank).
When you enter your username and password, attackers capture your login details.


Spear Phishing

A targeted attack where a scammer sends a message using your name or school/company details, making it look more real.
Example: “Hi John, your school account needs updating. Click here.”
Summary..
Phishing works by tricking people, not computers. So being careful and thinking before clicking is the best protection.

Personal Computers (PCs) are computers designed for use by one person at a time...

Some common examples are:
🖥️Desktop Computer – A computer kept on a desk, usually used in homes, offices, and schools.
💻Laptop – A portable computer that can be carried easily and used anywhere.
💻Notebook Computer – A smaller and lighter type of laptop.
📱Tablet Computer – A touchscreen computer that is easy to carry.
🖥️Workstation – A powerful personal computer used for tasks like graphic design, engineering, and video editing.
📱Smart phones

Software Threats to Computers...
Software threats are harmful programs or actions that can damage computer software, steal information, or disturb the normal operation of a computer system.

Examples of Software Threats

✂️Viruses – Malicious programs that attach to files and spread to other computers, damaging data.
✂️Worms – Programs that spread automatically through networks and slow down systems.
✂️Trojan Horses – Harmful programs that appear as useful software but secretly damage the system or steal data.
✂️Spyware – Software that secretly collects personal information from a computer.
✂️Ransomware – Malicious software that locks or encrypts files and demands money to unlock them.
✂️Computer Hacking – Unauthorized access to computer systems to steal or change data.

How to Prevent Software Threats

✂️Install antivirus software and keep it updated.
✂️Update the operating system and applications regularly.
✂️Do not download software from unknown or untrusted websites.
✂️Avoid opening suspicious email attachments or links.
✂️Use strong passwords and change them regularly.
✂️Backup important data regularly.

Physical Threats of ICT Devices...
Physical threats are damages or dangers that affect ICT devices such as computers, servers, and network equipment due to physical conditions or actions.
Examples of Physical Threats
Theft – Stealing computers, laptops, or other ICT equipment.
Fire – Fire accidents can destroy devices and stored data.
Water Damage – Spilling liquids or floods can damage electronic components.
Dust and Dirt – Dust can block cooling systems and damage internal parts.
Power Problems – Power cuts, power surges, or lightning can damage devices.
Physical Damage – Dropping or mishandling devices can break hardware.
How to Prevent Physical Threats
Use security locks and CCTV to prevent theft.
Install fire alarms and fire extinguishers in computer rooms.
Keep liquids away from ICT equipment.
Clean devices regularly to avoid dust buildup.
Use UPS or surge protectors to protect from power problems.
Handle devices carefully and keep them in safe places.

Main features of a computer...
✔️Speed – A computer can process data and perform calculations much faster than humans.
✔️Accuracy – It gives correct results if the instructions (programs) are correct.
Automation – Once a program is started, the computer can work automatically without human help.
✔️Storage – Computers can store a large amount of data and retrieve it whenever needed.
✔️Versatility – They can perform many types of tasks (calculations, word processing, graphics, internet browsing, etc.).
✔️Connectivity – Computers can connect with other devices and networks (like the internet) for communication and sharing information.
✔️Multitasking – They can run multiple programs at the same time (e.g., listening to music while typing a document).
✔️Diligence – Unlike humans, computers don’t get tired or bored. They can repeat tasks continuously without loss of efficiency.
✔️Programmable – Their functions depend on the software or instructions given to them.
Data Communication – Computers can send and receive data quickly across the world.

Types of Computers...
1. Supercomputer
Extremely powerful and fast.
Used for scientific research, weather forecasting, space exploration, nuclear simulations, etc.
Example: Fugaku (Japan), Summit (USA).
2. Mainframe Computer
Very large and powerful.
Can process and store huge amounts of data.
Used by banks, airlines, and government departments.
3. Minicomputer (Mid-range computer)
Smaller than mainframes but still powerful.
Used by small organizations for tasks like database management.
Not very common today.
4. Microcomputer (Personal Computer)
Most common type, designed for individual use.
Examples: Desktop PCs, Laptops, Tablets.
5. Workstation
More powerful than a normal personal computer.
Used for technical tasks like graphic design, engineering, or video editing.
6. Servers
Provide services to other computers in a network.
Examples: Web servers, File servers, Database servers.
7. Embedded Computer
Small computers built inside other devices to control them.
Found in washing machines, cars, ATMs, smart TVs, etc.

Plagiarism...