CPU Architecture and the Fetch-Execute Cycle
The roles of processor components, registers and buses as instructions and data move through the fetch-decode-execute cycle.
How to study for GCSE Computer Science
Move repeatedly between problem, algorithm, trace, code, test evidence and system explanation; use the exact language and assessment format required by your current board.
Core concepts
Concept 1
The CPU coordinates processing through the control unit, arithmetic logic unit, registers and communication pathways.
Exam cue: Trace what value moves, where it moves and why during each cycle stage.
Concept 2
The fetch-decode-execute cycle retrieves an instruction, interprets it and performs the required operation while updating processor state.
Exam cue: Keep an address distinct from the data stored at that address.
Concept 3
Registers hold small, immediately needed values such as addresses, instructions, data and intermediate results; exact named-register lists vary by board.
Exam cue: Use the register names and bus model required by the current specification.
Risk pitfalls and guardrails
Describing the CPU as storage for all programs and files.
Guardrail: Do not substitute one board's syntax, protocol list, language version or extension topic for the multi-board core; check the current specification and exam year.
Confusing the program counter's address with the current instruction itself.
Guardrail: Do not substitute one board's syntax, protocol list, language version or extension topic for the multi-board core; check the current specification and exam year.
Memorising one board's register list as a universal DfE list.
Guardrail: Do not substitute one board's syntax, protocol list, language version or extension topic for the multi-board core; check the current specification and exam year.
Memory anchors
CPU
The processor that fetches, decodes and executes instructions.
Control unit
The CPU component coordinating instruction processing and control signals.
ALU
The CPU component performing arithmetic and logical operations.
Register
A small fast storage location within the processor.
Fetch-execute cycle
The repeated process of fetching, decoding and executing instructions.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
What is the CPU's central role?
What does the control unit do?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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