Advantages and disadvantages of parallel transmission

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Quick Questions

Shade in the A or B circle for each question.

1. Parallel transmission over a short distance, such as inside a computer, is...

A Fast, because several bits are sent at once

B Slow, because only one bit is sent at a time

2. Which is a disadvantage of parallel transmission?

A It needs more wires, so the cables cost more

B It needs only one wire, so data is lost

3. Why is parallel transmission unreliable over long distances?

A The wires run out of bits to send

B Interference between the wires corrupts the data

4. Where is parallel transmission best suited?

A Long cables between cities

B Short links inside a computer, such as between the CPU and memory

5. Which statement about the cost of parallel transmission is correct?

A It costs more because it needs more wires

B It costs less because it needs fewer wires than serial

Match the Pairs

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

Left column		Right column
18 bits sent at once on 8 wires		AParallel needs more wires than serial, which makes it more expensive, not cheaper.
232 wires in a cable		BParallel is unreliable over long distances because of interference between wires. It is best for short distances.
3Parallel transmission is suited to very short links, such as inside a computer		CParallel transmission needs more wires, so the cable costs more to make
4Over long distances, parallel transmission becomes unreliable because wires interfere with each other		DBits on neighbouring wires interfere, so data arrives corrupted over a 50 m cable
5"Parallel transmission is best for sending data over long distances."		EParallel transmission sends several bits per clock tick, so it is fast over a short distance
6"Parallel transmission needs fewer wires than serial, so it is cheaper."		FData bus between the CPU and RAM

Definitions

parallel transmission

Fill in the Blanks

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

bitsPerTick ← 8 wiresNeeded ← ___________

bitsPerTick ← 8 clockTicks ← 4 bitsSent ← bitsPerTick _ clockTicks

wireCost ← 2 totalCost ← wiresNeeded * ________

__ distance = "long" THEN OUTPUT "Interference: unreliable" ENDIF

IF link = "inside computer" THEN ______ "Use parallel" ENDIF

Spot the Error

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

Question 1

A mode ← "PARALLEL"

B bitsPerTick ← 8

C distance ← "SHORT"

D speed ← "SLOW"

Question 2

A link ← "PARALLEL"

B wires ← 8

C cost ← "LOWER"

Question 3

A IF link = "SERIAL" THEN

B wires ← 8

C ENDIF

Question 4

A distance ← 0.1

B IF distance > 1 THEN

C mode ← "PARALLEL"

D ENDIF

Question 5

A distance ← 50

B IF distance > 10 THEN

C mode ← "SERIAL"

D reason ← "LOW COST"

E ENDIF

Answer Key

Advantages and disadvantages of parallel transmission

Section A: Quick Questions

A — Fast, because several bits are sent at once

A — It needs more wires, so the cables cost more

B — Interference between the wires corrupts the data

B — Short links inside a computer, such as between the CPU and memory

A — It costs more because it needs more wires

Section B: Match the Pairs

8 bits sent at once on 8 wires → Parallel transmission sends several bits per clock tick, so it is fast over a short distance

32 wires in a cable → Parallel transmission needs more wires, so the cable costs more to make

Parallel transmission is suited to very short links, such as inside a computer → Data bus between the CPU and RAM

Over long distances, parallel transmission becomes unreliable because wires interfere with each other → Bits on neighbouring wires interfere, so data arrives corrupted over a 50 m cable

"Parallel transmission is best for sending data over long distances." → Parallel is unreliable over long distances because of interference between wires. It is best for short distances.

"Parallel transmission needs fewer wires than serial, so it is cheaper." → Parallel needs more wires than serial, which makes it more expensive, not cheaper.

Section C: Definitions

parallel transmission — Sends several bits at once on many wires. Fast over short distances, but needs more wires (higher cost) and is unreliable over long distances because of interference between wires.

Section D: Fill in the Blanks

bitsPerTick ← 8
wiresNeeded ← bitsPerTick

bitsPerTick ← 8
clockTicks ← 4
bitsSent ← bitsPerTick * clockTicks

wireCost ← 2
totalCost ← wiresNeeded * wireCost

IF distance = "long" THEN
    OUTPUT "Interference: unreliable"
ENDIF

IF link = "inside computer" THEN
    OUTPUT "Use parallel"
ENDIF

Section E: Spot the Error

D — Parallel transmission sends several bits at once, so over a short distance it is fast. The line should be speed ← "FAST".

C — Parallel needs many wires, so the cable and connectors cost more. The line should be cost ← "HIGHER".

A — Using 8 wires is a feature of parallel transmission, not serial (which uses one wire for data). The test should be IF link = "PARALLEL" THEN.

B — Parallel is best over short distances, so the test should be distance < 1. Using > would choose parallel for long distances, where it is unreliable.

D — Parallel is avoided over long distances because interference between the wires makes it unreliable. The line should be reason ← "INTERFERENCE".