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A1.1 Computer hardware and operationA1.1.5

Fetch, decode and execute cycle

Describe the fetch, decode and execute cycle

SL + HL≈ 35 minCommand term: DescribePremium

In this lesson

  • The basic operations a CPU carries out to execute one machine-language instruction
  • How memory and registers interact through the address, data and control buses

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What's inside

  1. LearnOne instruction, three phases
  2. CheckQuick check
  3. LabStep through the CPU
  4. CheckQuick check
  5. CheckOrder the steps
  6. CheckQuick check
  7. CodeThe cycle as a Python loop
  8. ExamWorked exam answer
  9. PracticeTrace table
  10. ReviewMistakes examiners see
  11. Exam practiceExam-style questions

Ends with 5 exam-style questions worth 12 marks, with a self-marking markscheme.