Data Transmission IGCSE Computer Science

Data Transmission (IGCSE Computer Science)

• Data transmission involves moving data from one location (e.g., computer) to another.
• Networks connect two or more computers to share resources, exchange files, and enable communication.
• Network connections use various methods, including cables, phone lines, radio waves, satellites, and infrared light beams.

Network Types

• Local Area Network (LAN): Connects computers within a limited geographical area like a home or office.
• Wide Area Network (WAN): Connects computers over a large geographical area, potentially spanning countries or continents.

Network Connection

• Direct connection is suitable for small LAN with few computers.
• This method is impractical for large WAN systems where millions of computers connect randomly and need to exchange data.

Circuit Switching

• A dedicated communication path is established for the duration of data transmission.
• Steps involved: connection establishment, data transfer, and disconnection.
• This method is inefficient for random communication needs.

Packet Switching

• Data is broken into smaller units called packets.
• Each packet takes its own route to the destination.
• Routers determine the shortest possible path for each packet in the network.
• Packets may arrive at the destination in a different order than sent.

Packet Format

• Packets consist of a header, payload, and trailer.
• Header includes source and destination addresses, sequence number, packet size.
• Payload contains the actual data being transmitted.
• Trailer includes error-checking information.

Packet Switching Benefits

• Overcomes failed/busy lines and re-routes packets.
• Scalable for large networks.
• Efficient data transmission over long distances.

Packet Switching Drawbacks

• Packets can be lost and need retransmission.
• Susceptible to errors, especially in real-time scenarios.
• Can introduce delays due to packet reordering.

Transmission Factors

• Direction: Simplex (one way), half-duplex (both ways, but not simultaneously), and full-duplex (both ways simultaneously).
• Method: Serial (bits sent one by one) and parallel (bits sent simultaneously). Serial is suitable for longer distances; parallel is faster but requires more wires.
• Synchronization: Asynchronous (no timing mechanism between devices) and Synchronous (devices share a common timing mechanism).

Transmission Modes

• Simplex: Data transmission in one direction only (e.g., sending data from the keyboard to the CPU).
• Half-duplex: Data transmission in both directions, but not simultaneously (e.g., walkie-talkies).
• Full-duplex: Data transmission in both directions simultaneously (e.g., internet cables).

UNIVERSAL SERIAL BUS (USB)

• A serial data transmission method.
• Supports both half-duplex and full-duplex transmission.
• Uses a four-wire shielded cable.
• Two wires for power/earth, two for data transmission.
• USB devices are automatically detected and configured (driver loaded).
• New devices require drivers for effective communication. May require manual download if the driver's not available.

USB Benefits and Drawbacks

• Benefits: Automatic device detection, simple connection, wide availability.
• Drawbacks: Limited data transfer speed compared to other methods, particularly newer Ethernet lines. Length limitations; extension hubs are necessary. Early USB versions might only be supported by older devices.

This quiz covers the fundamentals of data transmission and network types as outlined in IGCSE Computer Science. Explore key concepts such as Local Area Networks (LAN) and Wide Area Networks (WAN), and understand the methods of connecting computers for effective communication. Test your knowledge on circuit switching and the various technologies used for data transmission.