The Fetch-Execute Cycle (AQA GCSE Computer Science): Flashcards
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Fetch-Execute cycle definition
Fetch-Execute cycle definition
Continuous repeating process in processor that runs programs
Three stages of Fetch-Execute cycle
Three stages of Fetch-Execute cycle
Fetch, Decode, Execute
What happens in Fetch stage
What happens in Fetch stage
Processor retrieves next instruction from memory
Memory address purpose
Memory address purpose
Specific location where instructions are stored
Register in Fetch-Execute cycle
Register in Fetch-Execute cycle
Temporary storage area for fetched instruction
What happens in Decode stage
What happens in Decode stage
Control unit examines instruction & works out what to do
Control unit function
Control unit function
Decodes instructions to work out what needs to be done
What happens in Execute stage
What happens in Execute stage
Processor carries out the decoded instruction
ALU function
ALU function
Performs mathematical calculations during Execute stage
Order of Fetch-Execute stages
Order of Fetch-Execute stages
Must always be Fetch, then Decode, then Execute
When Fetch-Execute cycle repeats
When Fetch-Execute cycle repeats
Immediately after Execute stage finishes
Speed of modern processors (cycles/second)
Speed of modern processors (cycles/second)
Millions or billions of cycles per second
Cache memory definition
Cache memory definition
Small, fast storage between processor & main memory
How cache memory speeds up the cycle
How cache memory speeds up the cycle
Stores frequently-used instructions closer to processor