Control bus

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. What does the control bus carry?

A The data being processed by the CPU

B Control signals such as read and write

2. Which component sends signals along the control bus to the other components?

A Control unit (CU)

B Arithmetic logic unit (ALU)

3. The control bus carries the memory address of the next instruction.

A False

B True

4. The CPU needs to fetch an instruction from RAM. Which signal does the control bus send to RAM?

A Read signal

B Write signal

5. The CPU needs to store a result in RAM. Which signal is sent along the control bus?

A Read signal

B Write signal

Match the Pairs

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

Left column		Right column
1control bus		AA set of wires that carries control signals from the control unit to other components
2read signal		BCU -> control bus -> RAM: write
3The control bus carries write signals, which tell memory to store data		CA control signal telling memory to send the data at an address back to the CPU
4The control bus carries signals only, not data or addresses		DThe data bus carries data, not the control bus. The control bus only carries control signals such as read and write.
5The control bus carries the data being read from RAM to the CPU		EThe address bus carries addresses. The control bus carries control signals sent from the control unit.
6The control bus carries the memory address of the next instruction		Fcontrol bus = signals; data bus = data; address bus = addresses

Definitions

control bus

Fill in the Blanks

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

The _______ bus carries read/write signals

CU sends a ____ signal on the control bus

A _____ signal tells RAM to store data

The __ sends signals along the control bus

Control bus carries no ____ or addresses

Spot the Error

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

Question 1

A CU sends READ on control bus

B RAM reads the address bus

C RAM puts data on control bus

Question 2

A CU sends READ signal

B Address bus carries address

C RAM finds that location

D RAM overwrites that location

Question 3

A Control bus carries signals

B Signals go from CU to others

C Example signals: address, data

Question 4

A Control bus starts at the RAM

B Signals travel to RAM and I/O

C This keeps components in sync

Question 5

A Data bus carries data

B Control bus carries data too

C Address bus carries addresses

Answer Key

Control bus

Section A: Quick Questions

B — Control signals such as read and write

A — Control unit (CU)

A — False

A — Read signal

B — Write signal

Section B: Match the Pairs

control bus → A set of wires that carries control signals from the control unit to other components

read signal → A control signal telling memory to send the data at an address back to the CPU

The control bus carries write signals, which tell memory to store data → CU -> control bus -> RAM: write

The control bus carries signals only, not data or addresses → control bus = signals; data bus = data; address bus = addresses

The control bus carries the data being read from RAM to the CPU → The data bus carries data, not the control bus. The control bus only carries control signals such as read and write.

The control bus carries the memory address of the next instruction → The address bus carries addresses. The control bus carries control signals sent from the control unit.

Section C: Definitions

control bus — A set of wires that carries control signals, such as read and write, from the control unit to other components so they work together. It carries signals, not data or addresses.

Section D: Fill in the Blanks

The control bus carries read/write signals

CU sends a read signal on the control bus

A write signal tells RAM to store data

The CU sends signals along the control bus

Control bus carries no data or addresses

Section E: Spot the Error

C — The control bus only carries control signals. The data being read goes on the data bus, so the line should be 'RAM puts data on data bus'.

D — A READ signal tells RAM to copy the data out without changing it. Overwriting a location is what a WRITE signal does. The line should be 'RAM copies data to data bus'.

C — Addresses and data travel on the address bus and data bus. Examples of control signals are READ and WRITE.

A — Control signals come from the control unit (CU), not from RAM. The line should be 'Control bus starts at the CU'.

B — The control bus carries control signals only. Data is carried by the data bus. The line should be 'Control bus carries signals'.