Serial and parallel transmission
Bits one by one or all at once, skew, crosstalk and USB.
Transcript
Serial transmission sends one bit at a time, over a single wire.
It works over long distances and arrives fully synchronised, but at a slower rate.
Parallel transmission sends several bits, usually one byte, over several wires at the same time.
It works well over short distances, like the circuits inside a computer, where high speed is essential.
Over long distances, parallel data suffers from skew: bits arrive at slightly different times, or even out of order.
Crosstalk between the wires also causes interference if the cable is too long.
The universal serial bus, or U S B, sends data serially.
Its advantages include a standard connector, devices detected automatically, power supplied to devices, and backwards compatibility.
Its disadvantages include a limited cable length, and a slower speed than some other connections.
Serial for distance, parallel for short, fast links. And U S B is serial.
More in this series
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.
1:21Error 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.