Advantages and disadvantages of serial transmission

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. Why is serial transmission cheaper to wire than parallel transmission?

A It needs fewer wires, so less cable is used

B It needs more wires, so the cable is stronger

2. Which statement about skew is correct for serial transmission?

A There is no skew, so the bits stay in step

B Skew is a big problem because bits travel side by side

3. Which type of transmission is better suited to long distances?

A Parallel transmission

B Serial transmission

4. A school needs to send a very large video file. What is a disadvantage of serial transmission here?

A It is slower, because bits are sent one at a time

B It is faster, because every bit has its own wire

5. Which is an advantage of serial transmission?

A It sends a whole byte at the same time

B Data arrives in the correct order and stays in step

Match the Pairs

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

Left column		Right column
1serial: 1 wire, bits sent one at a time		ASkew is a problem for parallel transmission, not serial. Serial has no skew, so it is reliable over long distances
2serial: long cable run, no skew		Bserial: 1 bit per pulse \| parallel: 8 bits per pulse
3Serial is slower than parallel for large amounts of data at the same clock speed, because only 1 bit is sent per clock pulse		CSerial transmission needs fewer wires, so cabling is cheaper
4Serial transmission has no skew, so the data stays in step and arrives in the correct order		DSerial transmission stays reliable over long distances because bits cannot get out of step
5Serial is faster than parallel because it only uses one wire		EFewer wires does not make serial faster. Serial sends one bit at a time, so it is slower than parallel for large amounts of data at the same clock speed
6Serial is unreliable over long distances because of data skew		Fwire 1: 1 0 1 1 0 0 1 0 (one wire, one order)

Definitions

serial transmission

Fill in the Blanks

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

serialWires ← _

skewHappens ← _____

serialCost _ parallelCost

IF bitsToSend > 1000000 THEN ______ "Serial is slower" ENDIF

longDistanceOK ← ____

Spot the Error

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

Question 1

A wires ← 8

B skew ← FALSE

C OUTPUT wires, skew

Question 2

A mode ← "serial"

B cost ← "high"

C OUTPUT mode, cost

Question 3

A distance ← 500

B IF distance < 100 THEN

C mode ← "serial"

D ENDIF

Question 4

A mode ← "serial"

B wires ← 1

C IF mode = "serial" THEN

D skew ← TRUE

E ENDIF

Question 5

A bits_per_tick ← 8

B ticks ← 800 DIV bits_per_tick

C OUTPUT ticks

Answer Key

Advantages and disadvantages of serial transmission

Section A: Quick Questions

A — It needs fewer wires, so less cable is used

A — There is no skew, so the bits stay in step

B — Serial transmission

A — It is slower, because bits are sent one at a time

B — Data arrives in the correct order and stays in step

Section B: Match the Pairs

serial: 1 wire, bits sent one at a time → Serial transmission needs fewer wires, so cabling is cheaper

serial: long cable run, no skew → Serial transmission stays reliable over long distances because bits cannot get out of step

Serial is slower than parallel for large amounts of data at the same clock speed, because only 1 bit is sent per clock pulse → serial: 1 bit per pulse | parallel: 8 bits per pulse

Serial transmission has no skew, so the data stays in step and arrives in the correct order → wire 1: 1 0 1 1 0 0 1 0 (one wire, one order)

Serial is faster than parallel because it only uses one wire → Fewer wires does not make serial faster. Serial sends one bit at a time, so it is slower than parallel for large amounts of data at the same clock speed

Serial is unreliable over long distances because of data skew → Skew is a problem for parallel transmission, not serial. Serial has no skew, so it is reliable over long distances

Section C: Definitions

serial transmission — Sends bits one at a time down one wire: cheaper, no skew and reliable over long distances, but slower than parallel for large amounts of data at the same clock speed.

Section D: Fill in the Blanks

serialWires ← 1

skewHappens ← FALSE

serialCost < parallelCost

IF bitsToSend > 1000000 THEN
    OUTPUT "Serial is slower"
ENDIF

longDistanceOK ← TRUE

Section E: Spot the Error

A — Serial transmission sends bits down a single wire, so wires should be 1. Eight wires would be parallel transmission.

B — Serial needs fewer wires than parallel, so it is cheaper to wire. The cost should be "low".

B — Serial suits long distances, so the test should be distance > 100. The < sign checks for short distances.

D — With one wire, bits cannot arrive out of step, so serial has no skew. skew should be set to FALSE.

A — Serial sends only 1 bit per clock tick. Sending 8 bits per tick describes parallel transmission.