Grade 9 · Unit 2: Data transmission · IGCSE Computer Science

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Revision videos, vocabulary practice and written questions for IGCSE.

IGCSE Computer Science

10 videos

Revision videos for IGCSE Computer Science, unit by unit: Grade 9 data representation, data transmission and hardware.

Grade 9 · Unit 2: Data transmission

1:32

Data packets and packet switching

Packet structure, routing, out-of-order arrival and reassembly.

packetsrouters
1:19

Simplex, half-duplex and full-duplex

Which way the data flows, and when.

transmission mode
1:43

Serial and parallel transmission

Bits one by one or all at once, skew, crosstalk and USB.

serialparallelUSB
1:21

Error detection

Why errors happen, and checksums, echo checks and ARQ.

checksumARQ
1:13

Parity checks

Parity bits and parity blocks, including finding and fixing a flipped bit.

parityerrors
1:32

Check digits

The multiply, add, divide-by-10 method with a worked example and a practice question.

check digitworked example
1:28

Encryption

Eavesdroppers, symmetric keys and the public and private key pair.

encryptionkeys
5:08

Unit 2 quiz

Ten questions with a think-time countdown and explained answers.

quizrevision
1:32

Crosstalk in transmission

How a signal leaks into a neighbouring wire, corrupts data, and how twisted pairs and shielding fix it.

crosstalkinterferencetwisted pair
1:48

When to use serial or parallel

Choosing between serial and parallel: inside a computer, computer to printer, USB, Ethernet and a distance rule of thumb.

serialparallelprinterUSB