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In a stored-program computer, main memory holds both instructions and data in addressable locations. The CPU fetches instructions and coordinates their execution. The control unit directs operations, while the arithmetic logic unit performs arithmetic and logical work. Registers are small fast storage locations within the processor; cache stores frequently needed information close to the CPU. An embedded system is designed for a particular function within a larger device.
Video by Craig'n'Dave. The video’s own board label is retained; follow the specification reference and scope notes on this lesson for assessed content.
Viewing focus: Explain the stored-program concept
After watching, attempt these questions before opening the answers. You can also use the written lesson below.
After watching 1: Which unit performs arithmetic?
ALU. The arithmetic logic unit carries out arithmetic and logic operations.
After watching 2: What does the MAR hold?
A memory address. It identifies the location being accessed.
What you'll be able to do
In a stored-program computer, main memory holds both instructions and data in addressable locations. The CPU fetches instructions and coordinates their execution. The control unit directs operations, while the arithmetic logic unit performs arithmetic and logical work. Registers are small fast storage locations within the processor; cache stores frequently needed information close to the CPU. An embedded system is designed for a particular function within a larger device.
The program counter identifies the next instruction address. The address passes to the memory address register; memory supplies the instruction through the memory data register, and it is held for decoding. The program counter is normally advanced before subsequent execution can change it. The decoded operation may use the ALU, transfer data or branch. Trace the actual values and instruction order instead of repeating the cycle words without explaining the state changes.
A higher clock rate can allow more processing steps per second, but useful work also depends on architecture, memory access and the program. More cores help workloads that can be split, but do not guarantee that one sequential program runs proportionally faster. More cache can reduce slower memory accesses. Compare processors using the workload and evidence supplied, rather than declaring the one with the largest single number universally fastest.
Attempt these problems on paper before opening the worked reasoning. Explain your steps as well as giving a final answer.
Common mistakes to avoid
Key takeaways
Question 1: Why might four cores fail to make a sequential calculation four times faster?
Available parallelism limits the speed-up.
Check the assessed scope and practical or mathematical requirements.
An external explanation or interactive activity to use alongside the lesson. It may include extension material.
Close the notes and answer from memory. Revisit any explanation you cannot yet reconstruct.
Test yourself
Answer a few questions, then review anything you missed.
Start with the quiz above to check the key ideas. You can also choose another topic from the practice library.