Comparing serial and parallel transmission

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Quick Questions

Shade in the A or B circle for each question.

1. Which method sends several bits at the same time down several wires?

A Parallel transmission

B Serial transmission

2. Which method is better for sending data over a long distance?

A Parallel transmission

B Serial transmission

3. Which statement is correct?

A Parallel is faster than serial over a long distance

B Parallel is faster than serial over a short distance

4. Why is parallel transmission unreliable over long distances?

A Bits can arrive out of sync because of data skew

B It can only send 1 bit at a time

5. Which method usually costs less to wire up?

A Serial, because it needs fewer wires

B Parallel, because it needs fewer wires

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1Serial: 1 bit at a time, 1 wire		ASerial uses only one wire, so it needs less wiring and is cheaper. Parallel uses many wires, which costs more.
2Parallel: 8 bits at once, 8 wires		Bdistance = "short" method = "parallel"
3Over a long distance, serial is the better choice because the bits stay in step and arrive reliably		CSerial sends one bit after another down a single wire, so it needs less wiring and costs less.
4Over a very short distance, parallel can be faster because many bits travel at once		Ddistance = "long" method = "serial"
5Parallel is best for sending data over long distances because it uses more wires		EParallel is not suited to long distances. Data skew makes bits arrive at different times and the data becomes unreliable. Serial is better for long distances.
6Serial is more expensive than parallel because it needs more wires		FParallel sends several bits at the same time down separate wires, so it is faster but only over short distances.

Definitions

serial vs parallel

Fill in the Blanks

Complete each line of code by filling in the missing parts.

serial: bits sent at once = _

parallel: bits sent at once = ____

long distance: ______ is more reliable

parallel over distance causes data ____

short distance, high speed: ________

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A serial: bits at once = 1

B parallel: bits at once = 8

C longer distance: parallel

Question 2

A serial: wires = 1

B parallel: wires = 1

C cheaper wiring: serial

Question 3

A serial: sends 8 bits at once

B parallel: sends 8 bits at once

C short range: parallel faster

Question 4

A distance ← "long"

B IF distance = "long" THEN

C method ← "parallel"

D ENDIF

Question 5

A Feature | Serial | Parallel

B Bits at once | 1 | many

C Wires | 1 | several

D Cost | higher | lower

E Short range | slower | faster

Answer Key

Comparing serial and parallel transmission

Section A: Quick Questions

A — Parallel transmission

B — Serial transmission

B — Parallel is faster than serial over a short distance

A — Bits can arrive out of sync because of data skew

A — Serial, because it needs fewer wires

Section B: Match the Pairs

Serial: 1 bit at a time, 1 wire → Serial sends one bit after another down a single wire, so it needs less wiring and costs less.

Parallel: 8 bits at once, 8 wires → Parallel sends several bits at the same time down separate wires, so it is faster but only over short distances.

Over a long distance, serial is the better choice because the bits stay in step and arrive reliably → distance = "long" method = "serial"

Over a very short distance, parallel can be faster because many bits travel at once → distance = "short" method = "parallel"

Parallel is best for sending data over long distances because it uses more wires → Parallel is not suited to long distances. Data skew makes bits arrive at different times and the data becomes unreliable. Serial is better for long distances.

Serial is more expensive than parallel because it needs more wires → Serial uses only one wire, so it needs less wiring and is cheaper. Parallel uses many wires, which costs more.

Section C: Definitions

serial vs parallel — Serial sends 1 bit at a time down one wire: cheaper, reliable, better over long distance. Parallel sends many bits at once down several wires: faster over short distances only.

Section D: Fill in the Blanks

serial: bits sent at once = 1

parallel: bits sent at once = many

long distance: serial is more reliable

parallel over distance causes data skew

short distance, high speed: parallel

Section E: Spot the Error

C — Serial is the better choice over longer distances because parallel suffers from data skew. Line 3 should read 'longer distance: serial'.

B — Parallel transmission uses several wires, one per bit, so it does not use 1 wire. It should be 'parallel: wires = 8'.

A — Serial sends only 1 bit at a time down a single wire. Sending many bits at once is parallel.

C — Over a long distance parallel suffers from data skew and costs more, so serial should be chosen. Line 3 should be method ← "serial".

D — The cost values are swapped. Serial needs only one wire so it is cheaper, while parallel needs several wires so it costs more.