Serial transmission

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Quick Questions

Shade in the A or B circle for each question.

1. How does serial transmission send data?

A One bit at a time down a single wire

B Many bits at the same time down several wires

2. How many wires or channels does serial transmission use to carry the data bits?

A One

B Eight or more

3. A byte (8 bits) is sent using serial transmission. How are the 8 bits sent?

A One after another, in a line

B All 8 together at the same moment

4. The bits 1 0 1 1 are sent by serial transmission. What order do they arrive in?

A Any order, because each bit takes its own path

B 1 0 1 1, the same order they were sent

5. Why do bits arrive in order in serial transmission?

A They travel along different wires at different speeds

B They all travel along the same single wire

Match the Pairs

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

Left column		Right column
1serial transmission		Asent: 1 0 1 1 / received: 1 0 1 1
21 0 1 1 0 0 1 0 (sent along one wire)		BA byte sent serially: each bit travels in turn and they arrive in the same order they were sent
3Serial transmission uses only one wire, so every bit has to share it		CSending data one bit at a time, one after another, down a single wire or channel
4In serial transmission the bits arrive in the same order they were sent		Dwires = 1
5Serial transmission sends 8 bits at the same time down 8 wires		EThis describes parallel transmission. Serial sends one bit at a time down a single wire.
6Serial transmission: bits can arrive in a different order than they were sent		FIn serial transmission the bits arrive in the same order they were sent because they travel one after another on one wire.

Definitions

serial transmission

Fill in the Blanks

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

MODE ← SERIAL wires ← _ bitsAtATime ← 1

___ i ← 1 TO 8 SEND data[i] ON wire1 NEXT i

sent ← "10110010" received ← sent IF received _ sent THEN OUTPUT "In order"

bitsLeft ← 8 SEND nextBit bitsLeft ← bitsLeft _ 1

IF wires = 1 THEN mode ← ______ ENDIF

Spot the Error

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

Question 1

A data = "10110"

B for bit in data:

C send(data)

Question 2

A wires = 1

B bits_per_tick = 8

C ticks = 8 / bits_per_tick

Question 3

A data = "1101"

B received = ""

C for bit in data:

D received = bit + received

Question 4

A data ← "0110"

B FOR i ← 1 TO 3

C SEND data[i]

D NEXT i

Question 5

A data = "1011"

B for i in range(len(data)):

C print(data[0])

Answer Key

Serial transmission

Section A: Quick Questions

A — One bit at a time down a single wire

A — One

A — One after another, in a line

B — 1 0 1 1, the same order they were sent

B — They all travel along the same single wire

Section B: Match the Pairs

serial transmission → Sending data one bit at a time, one after another, down a single wire or channel

1 0 1 1 0 0 1 0 (sent along one wire) → A byte sent serially: each bit travels in turn and they arrive in the same order they were sent

Serial transmission uses only one wire, so every bit has to share it → wires = 1

In serial transmission the bits arrive in the same order they were sent → sent: 1 0 1 1 / received: 1 0 1 1

Serial transmission sends 8 bits at the same time down 8 wires → This describes parallel transmission. Serial sends one bit at a time down a single wire.

Serial transmission: bits can arrive in a different order than they were sent → In serial transmission the bits arrive in the same order they were sent because they travel one after another on one wire.

Section C: Definitions

serial transmission — Sending data one bit at a time, one after another, down a single wire or channel. The bits arrive in the same order they were sent.

Section D: Fill in the Blanks

MODE ← SERIAL
wires ← 1
bitsAtATime ← 1

FOR i ← 1 TO 8
   SEND data[i] ON wire1
NEXT i

sent ← "10110010"
received ← sent
IF received = sent THEN OUTPUT "In order"

bitsLeft ← 8
SEND nextBit
bitsLeft ← bitsLeft - 1

IF wires = 1 THEN
   mode ← SERIAL
ENDIF

Section E: Spot the Error

C — Serial transmission sends one bit at a time. send(data) would push every bit at once. It should be send(bit) inside the loop.

B — Serial transmission sends one bit per tick down a single wire. Setting 8 bits per tick describes parallel transmission. It should be bits_per_tick = 1.

D — In serial transmission the bits arrive in the same order they were sent. Putting each new bit at the front reverses the order. It should be received = received + bit.

B — The data has 4 bits and each one is sent separately down the wire. Looping only to 3 means the last bit is never sent. It should be FOR i ← 1 TO 4.

C — Each pass of the loop must send the next bit in order. data[0] sends the first bit every time. It should be print(data[i]).