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.
Transcript
Which one should we use? It mostly comes down to three things: distance, speed, and reliability.
Use parallel for short distances where speed matters most, like the buses between the processor and the memory inside a computer.
Older printers also used parallel cables, but only short, thick ones.
Use serial for longer distances, where bits must arrive in step and reliably, like U S B, Ethernet and the internet.
Serial needs fewer wires, so cables are thinner and cheaper, and there is less crosstalk.
Take a computer sending a page to a printer. An old parallel cable sends a whole byte at once, but it has to stay short.
A U S B cable sends the bits one after another down a thin cable, so it can be longer.
Data flows back too. The printer reports out of paper or low ink, and the same connection carries it to the computer.
As a rule of thumb: short and fast, choose parallel. Long distance or high reliability, choose serial.
Parallel inside the machine, serial between machines.
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.
1:43Serial 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.
1:32Crosstalk in transmission
How a signal leaks into a neighbouring wire, corrupts data, and how twisted pairs and shielding fix it.