Grade 9 · Unit 2: Data transmission
1:32Data packets and packet switching
Packet structure, routing, out-of-order arrival and reassembly.
1:19Simplex, half-duplex and full-duplex
Which way the data flows, and when.
1:43Serial and parallel transmission
Bits one by one or all at once, skew, crosstalk and USB.
1:21Error detection
Why errors happen, and checksums, echo checks and ARQ.
1:13Parity checks
Parity bits and parity blocks, including finding and fixing a flipped bit.
1:32Check digits
The multiply, add, divide-by-10 method with a worked example and a practice question.
1:28Encryption
Eavesdroppers, symmetric keys and the public and private key pair.
5:08Unit 2 quiz
Ten questions with a think-time countdown and explained answers.