Computer Architecture
5 things
4 things about the fetch-decode-execute cycle
4 things about how your CPU runs every single instruction
Quick check · tap an answer to continue
Lesson notes
Key points
- PC holds the next address: The program counter stores the memory address of the next instruction to fetch.
- Fetch into the IR: The instruction is copied from memory into the instruction register, and the PC increments.
- Control unit decodes: The control unit reads the opcode and sends signals to the right components.
- ALU executes: The ALU does arithmetic or logic, and results go to registers or memory.
- Jumps rewrite the PC: Branch instructions load a new address into the PC, changing what runs next.
Takeaway: Fetch with the PC, decode in the control unit, execute in the ALU.
Quick check: Which register holds the address of the next instruction to fetch?
- Instruction register
- Accumulator
- Program counter
The program counter points to the next instruction's address.
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