levo
Log inStart

Hardware: Architecture, Memory and Storage

The fetch-execute cycle

  • 3 things to know
  • AS Unit 1

Overview

Three stages of the fetch-execute cycle in order and purpose of the system clock.

What you need to know

Answer each one before you reveal it.

Your recallNot started
Process

Describe, in order, what happens during the fetch stage.

Process

State the three stages of the fetch-execute cycle in order.

Key term

Which bus carries the contents of the memory address register?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    State the three stages of the fetch-execute cycle in order.

    Model answer

    Fetch, decode, execute.

  2. 2

    Describe, in order, what happens during the fetch stage.

    Model answer

    The address in the program counter is copied to the memory address register, the program counter is incremented, the instruction at that address travels back along the data bus into the memory data register, and it is then copied into the current instruction register.

  3. 3

    At what point in the cycle is the program counter incremented, and why then?

    Model answer

    It is incremented during the fetch stage as soon as the address has been copied to the memory address register, so that it already points at the following instruction while the current one is still being carried out.

  4. 4

    What does the control unit do during the decode stage?

    Model answer

    It splits the contents of the current instruction register into opcode and operand and works out which internal circuits and data paths the operation requires.

  5. 5

    Give three different things that might happen during the execute stage.

    Model answer

    The arithmetic and logic unit may perform a calculation and leave the result in the accumulator, a value may be copied between a register and memory, or a new address may be loaded into the program counter.

  6. 6

    How does a jump instruction alter the normal flow of the cycle?

    Model answer

    It writes a new address into the program counter, so the next fetch takes the instruction from that address instead of the one that follows sequentially.

See the rest and revise

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.

1Closed book
2Open book
3Closed book

The 3-step method, run for you

Answer cold, learn it, then prove it stuck. Levo tracks the jump between your first attempt and your last.

Hardware: Architecture, Memory and Storage
Networks and Data Transmission
Logic Gates and Boolean Algebra
Data Representation and Data Types

Cram a whole paper in one sitting

Sort every topic into what you know and what you do not, then drill only the weak ones.

Fetch, , execute.
decodecompilestore

Blank Blitz makes facts automatic

Rapid timed gap-fills on the terms and numbers you need to recall without thinking.

AEncryption is reversible.
BThe stored form could be decrypted.
CA hash cannot be reversed.

Build It gets the exam shape right

Assemble a full-mark answer from its marking points, in the order an examiner wants them.

A bit is a single binary digit.
TrueFalse

Test It catches misconceptions

Spot the fault in a statement. The traps are the mistakes students actually make.

721941163128510

Brain Breaks between sessions

Short focus games to reset attention, so the next set lands better than the last.

Every question in Hardware: Architecture, Memory and Storage, on a schedule.

Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.

Start revising, £5 a monthSee how the method works

Or £46 a year, about £3.83 a month. Cancel anytime.