World Wide Web (WWW)

The World Wide Web (WWW) is a system of interlinked hypertext documents accessed via the
Internet. Invented by Tim Berners-Lee in 1989, it uses the Hypertext Transfer Protocol (HTTP)
to transmit data, allowing users to navigate and interact with websites seamlessly.

File Transfer Protocol (FTP)

File Transfer Protocol (FTP) is a standard network protocol used for transferring files between a
client and server over TCP/IP. It is commonly used for uploading and downloading files,
facilitating the exchange of large amounts of data over the Internet.

E-mail

Electronic mail (e-mail) is a method of exchanging digital messages across the Internet or other
computer networks. It operates using protocols like SMTP (Simple Mail Transfer Protocol),
IMAP (Internet Message Access Protocol), and POP3 (Post Office Protocol), enabling users to
send and receive messages efficiently.

DNS Addressing

Domain Name System (DNS) addressing translates human-friendly domain names (like
www.example.com) into IP addresses. This hierarchical and decentralized naming system is
essential for internet browsing and email services, ensuring that users can easily access websites
and services using readable names.

Liquid Crystal Display (LCD)

Liquid Crystal Display (LCD) technology is commonly used in TVs, computer monitors, and
mobile devices. It uses liquid crystals to modulate light and produce images, offering better
energy efficiency and slimmer designs compared to the older Cathode Ray Tube (CRT)
technology.

Cathode Ray Tube (CRT)

Cathode Ray Tube (CRT) technology, now mostly obsolete, uses electron beams to create
images on a phosphorescent screen. Once prevalent in TVs and monitors, CRTs are bulky and
consume more power compared to modern display technologies like LCDs.

Mouse

The mouse is a pointing device used to interact with a computer's graphical user interface. It
typically includes buttons and a scroll wheel, translating user movements into cursor movements
on the screen, facilitating navigation and interaction with software applications.
Telnet

Telnet is a network protocol that allows for remote login to another computer over the Internet.
Operating on TCP port 23, Telnet has largely been replaced by more secure protocols like SSH
due to its lack of encryption and security.

Keyboard

A keyboard is an input device used to enter text and commands into a computer. It includes keys
for letters, numbers, and functions, and can be mechanical, membrane, or virtual (on-screen),
providing a primary means of user input.

Types of Computer

Computers come in various types, including supercomputers, mainframes, minicomputers, and

microcomputers. Supercomputers are extremely fast and powerful, used for complex simulations
and calculations. Mainframes are large systems used by large organizations for bulk data
processing. Minicomputers, less powerful than mainframes, are used in mid-sized organizations,
while microcomputers, commonly known as personal computers (PCs), are used by individuals
and businesses.

Switch

A switch is a network device that connects multiple devices within a local area network (LAN).
Operating at the data link layer (Layer 2) of the OSI model, it filters and forwards data packets
between devices, improving network efficiency and performance.

Router

A router is a networking device that forwards data packets between computer networks.
Operating at the network layer (Layer 3) of the OSI model, it directs traffic on the Internet by
determining the best path for data, enabling efficient communication between networks.

Hub

A hub is a basic networking device that connects multiple Ethernet devices. Operating at the
physical layer (Layer 1) of the OSI model, it broadcasts data to all connected devices, leading to
potential data collisions and less efficient network performance compared to switches.

DSL (Digital Subscriber Line)

Digital Subscriber Line (DSL) is a family of technologies that provide internet access via
telephone lines. It offers higher data transfer rates compared to traditional dial-up connections,
with common types including ADSL (Asymmetric DSL) and VDSL (Very-high-bit-rate DSL).
WiMAX (Worldwide Interoperability for Microwave Access)

WiMAX is a wireless communication standard designed to provide high-speed internet over long
distances. Operating on the IEEE 802.16 standard, it can provide broadband access in rural and
remote areas, offering an alternative to wired internet connections.

IrDA (Infrared Data Association)

IrDA is a standard for wireless data transmission using infrared light. Commonly used for short-
range communication between devices, it has largely been replaced by Bluetooth and Wi-Fi
technologies due to its limited range and line-of-sight requirements.

Fiber Optics

Fiber optics technology uses thin strands of glass or plastic fibers to transmit data as light
signals. It offers high-speed and high-capacity data transmission over long distances, making it
ideal for internet, telephone, and television services.

USB (Universal Serial Bus)

Universal Serial Bus (USB) is a standard for connecting peripherals to a computer. It supports
data transfer and power supply, with versions including USB 1.0, 2.0, 3.0, and USB-C, providing
a versatile and widely-used interface for various devices.

Cache

Cache is a small, high-speed storage location that temporarily holds frequently accessed data. It
improves the speed and efficiency of data access, commonly used in CPUs and web browsers to
enhance performance and reduce latency.

SRAM/DRAM

Static Random-Access Memory (SRAM) is faster and more expensive, used for cache memory.
Dynamic Random-Access Memory (DRAM) is slower and cheaper, used for main system
memory. Both are types of volatile memory, losing data when power is turned off, but they play
crucial roles in computer performance and operation.

Programming Languages

Programming languages come in various forms, including low-level languages like assembly
language and machine code, which are close to hardware level. High-level languages like
Python, Java, and C++ are designed for easier programming and abstraction from hardware.
Scripting languages like JavaScript and PHP are often used for automating tasks and web
development, providing flexibility and efficiency in software development.
Here are detailed explanations suitable for exam answers:

1. Transmission Media

Transmission media are the physical pathways that connect computers,

devices, and people on a network. They can be categorized into two main
types: wired and wireless.

Wired Media

 Twisted Pair Cable:

o Description: Consists of pairs of insulated copper wires twisted

together.

o Types:

 Unshielded Twisted Pair (UTP): Common in LANs,

susceptible to interference.

 Shielded Twisted Pair (STP): Includes shielding to

reduce interference.

o Advantages: Inexpensive, easy to install.

o Disadvantages: Limited bandwidth, susceptible to interference.

 Coaxial Cable:

o Description: Central conductor surrounded by insulation,

metallic shield, and outer cover.

o Uses: Cable television, broadband internet.

o Advantages: Higher bandwidth than twisted pair, better

shielding.

o Disadvantages: Bulkier, more expensive.

 Fiber Optic Cable:

o Description: Uses light signals to transmit data through glass or

plastic fibers.

o Advantages: Extremely high bandwidth, immune to

electromagnetic interference.
 o Disadvantages: Expensive, fragile, difficult to splice.

Wireless Media

 Radio Waves:

o Description: Uses electromagnetic waves for communication.

o Uses: Wi-Fi, mobile networks, broadcasting.

o Advantages: Wireless connectivity, broad coverage.

o Disadvantages: Susceptible to interference, security concerns.

 Microwaves:

o Description: Uses high-frequency radio waves.

o Uses: Satellite communication, long-distance telephone

transmission.

o Advantages: High bandwidth, suitable for long distances.

o Disadvantages: Line-of-sight requirement, weather

interference.

 Infrared:

o Description: Uses infrared light for short-range communication.

o Uses: Remote controls, short-range data transfer.

o Advantages: No interference from radio frequencies.

o Disadvantages: Limited range, line-of-sight requirement.

2. Network Topologies

Network topologies refer to the arrangement of different elements (links,

nodes) in a computer network. Common types include:

 Mesh Topology:

o Description: Every node connects to every other node.

o Advantages:

 High reliability: Redundant paths increase fault tolerance.

 Direct communication: Reduces latency.

o Disadvantages:
  Expensive: High cost of cabling and hardware.

 Complex management: Difficult to install and configure.

 Star Topology:

o Description: All nodes are connected to a central hub or switch.

o Advantages:

 Easy to install and manage: Simple to add or remove

devices.

 Fault isolation: A failure in one connection doesn’t affect

others.

o Disadvantages:

 Central point of failure: Hub failure disrupts entire network.

 More cabling required compared to bus topology.

 Bus Topology:

o Description: All nodes share a single communication line (bus).

o Advantages:

 Simple and cost-effective: Requires less cabling.

 Easy to extend: Devices can be added easily.

o Disadvantages:

 Network slowdown: Performance degrades with more

devices.

 Single point of failure: Cable break affects the whole

network.

3. OSI Model Layers

The Open Systems Interconnection (OSI) Model is a conceptual

framework used to understand network interactions. It divides networking
into seven layers:

1. Physical Layer:

o Function: Transmits raw bit streams over a physical medium.

o Components: Cables, switches, NICs.

 o Protocols: Ethernet, USB.

2. Data Link Layer:

o Function: Provides node-to-node data transfer, error detection,

and correction.

o Components: Bridges, switches.

o Protocols: Ethernet, PPP, MAC.

3. Network Layer:

o Function: Manages packet forwarding, including routing through

different routers.

o Components: Routers.

o Protocols: IP, ICMP, ARP.

4. Transport Layer:

o Function: Ensures end-to-end communication, error recovery,

and flow control.

o Components: Gateways, firewalls.

o Protocols: TCP, UDP.

5. Session Layer:

o Function: Manages sessions or connections between

applications.

o Protocols: NetBIOS, RPC.

6. Presentation Layer:

o Function: Translates data formats, encrypts, and compresses

data.

o Protocols: SSL, TLS, JPEG.

7. Application Layer:

o Function: Interfaces directly with end-user applications.

o Protocols: HTTP, FTP, SMTP, DNS.

4. Types of Memory
Memory in computers is essential for storing data and instructions. Types
include:

 RAM (Random Access Memory):

o Function: Temporary storage for active processes and data.

o Characteristics: Volatile, fast access.

o Types: DRAM, SRAM.

 ROM (Read-Only Memory):

o Function: Permanent storage for firmware and system boot

processes.

o Characteristics: Non-volatile, read-only.

o Types: PROM, EPROM, EEPROM.

 Cache Memory:

o Function: High-speed memory for frequently accessed data.

o Characteristics: Faster than RAM, located close to the CPU.

o Levels: L1 (internal), L2, L3 (external).

 Virtual Memory:

o Function: Extends RAM using disk space.

o Characteristics: Slower than physical RAM, increases available

memory.

o Implementation: Paging, swapping.

5. Software

Software refers to programs and operating information used by a computer.

 Application Software:

o Description: Programs designed for end-users to perform

specific tasks.

o Examples: Word processors (Microsoft Word), spreadsheets

(Excel), web browsers (Chrome).

o Types: General-purpose (office suites), special-purpose (graphic

design tools).
  System Software:

o Description: Manages hardware resources and provides a

platform for applications.

o Examples: Operating systems (Windows, Linux), device drivers.

o Functions: Resource management, task scheduling, security

management.

6. IP Address

An IP address is a numerical label assigned to devices on a network,

enabling communication.

Addressing Scheme:

 IPv4:

o Format: 32-bit address, four octets (e.g., 192.168.1.1).

o Range: 0.0.0.0 to 255.255.255.255.

o Classes: A, B, C (public), D (multicast), E (experimental).

 IPv6:

o Format: 128-bit address, eight groups of four hexadecimal digits

(e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334).

o Advantages: Larger address space, improved security, better

auto-configuration.

7. System Bus

The system bus is a communication pathway used to connect the CPU,

memory, and other hardware components, facilitating data transfer.

 Components:

o Data Bus: Carries data between components.

o Address Bus: Carries addresses of data.

o Control Bus: Carries control signals.

 Functions:

o Data Transfer: Facilitates communication between the CPU and

peripherals.
 o Synchronization: Ensures data integrity and timing.

o Control: Directs operations within the computer.

8. Computer Network Components

 Modem:

o Function: Modulates and demodulates signals for internet

access.

o Types: DSL, cable, fiber-optic.

o Working: Converts digital signals to analog for transmission

over phone lines and vice versa.

 Hub:

o Function: Connects multiple devices in a network, broadcasting

data to all ports.

o Types: Active, passive, intelligent.

o Working: Operates at the physical layer, does not filter data.

 Switch:

o Function: Connects devices, forwards data to specific devices

based on MAC addresses.

o Types: Managed, unmanaged.

o Working: Operates at the data link layer, improves network

efficiency by reducing collisions.

 Router:

o Function: Routes data between different networks, manages

traffic.

o Working: Operates at the network layer, uses IP addresses to

forward packets.

9. Internet

The internet is a global network of interconnected computers that allows for

the exchange of information and resources.

Uses:
  Communication: Email, instant messaging, social media platforms.

 Information: Access to news, educational resources, research papers.

 Entertainment: Streaming services, online gaming, digital content.

 E-commerce: Online shopping, banking, transactions.

 Collaboration: Cloud-based tools, remote work applications.

10. Search Engine and Cloud Computing

 Search Engine:

o Description: Software system that searches the internet for

information based on user queries.

o Examples: Google, Bing, Yahoo.

o Functions: Indexing web pages, ranking results, providing

relevant information.

 Cloud Computing:

o Description: Delivery of computing services (e.g., servers,

storage, databases) over the internet.

o Types:

 IaaS (Infrastructure as a Service): Virtual machines,

storage.

 PaaS (Platform as a Service): Development platforms.

 SaaS (Software as a Service): Applications delivered

over the internet.

o Advantages: Scalability, cost-effectiveness, accessibility.

11. Storage Devices

 RAM (Random Access Memory):

o Function: Temporary storage for active processes.

o Characteristics: Volatile, fast access.

 ROM (Read-Only Memory):

o Function: Permanent storage for firmware and boot instructions.

 o Characteristics: Non-volatile, read-only.

 Hard Disk:

o Function: Long-term storage for data and applications.

o Characteristics: Magnetic storage, non-volatile, large capacity.

 Cache:

o Function: High-speed memory for frequently accessed data.

o Characteristics: Faster than RAM, improves processing speed.

12. Types of Microprocessors

 Single-core: One processing unit, suitable for basic tasks.

 Multi-core: Multiple processing units, allows parallel processing and

improved performance.

 ARM: Efficient processors used in mobile devices, known for low power
consumption.

 x86: Commonly used in desktops and laptops, supports complex

applications.

13. Printer Types

 Inkjet Printer:

o Description: Sprays liquid ink onto paper.

o Advantages: Good for high-quality photos, affordable.

o Disadvantages: Slower print speed, higher ink costs.

 Laser Printer:

o Description: Uses toner and laser technology to print.

o Advantages: Fast, efficient, good for text documents.

o Disadvantages: Higher initial cost, not ideal for photos.

 Dot Matrix Printer:

o Description: Impact printer that uses a print head to strike an

inked ribbon.

o Advantages: Durable, good for multipart forms.

 o Disadvantages: Low print quality, noisy.

 Thermal Printer:

o Description: Uses heat-sensitive paper for printing.

o Advantages: Quiet, no ink required.

o Disadvantages: Fades over time, limited to certain media.

14. Operating System Types

 Desktop OS: Designed for personal computers (e.g., Windows,

macOS, Linux).

 Mobile OS: Designed for mobile devices (e.g., Android, iOS).

 Server OS: Designed for servers, handling multiple users and tasks
(e.g., Windows Server, Linux distributions).

 Embedded OS: Designed for specific hardware, often in appliances

and devices (e.g., routers, smart TVs).