The CPU

Question 1

What is the purpose of the CPU? (2 marks)

Answer 1

1. To fetch, decode and execute instructions
2. To take an input, process data and produce an output
   (the “brain of the computer” made up of components and registers)

Question 2

What are the components of the CPU? And what do they have in common? (5 marks)

Answer 2

1. Arithmetic Logic Unit (ALU)
2. Control Unit (CU)
3. Cache
4. Registers
5. Each component sits within the CPU

Question 3

What is the function of the ALU? (2 marks)

Answer 3

1. Performs arithmetic operations
2. Performs logical decisions

Question 4

What is the function of the CU? (3 marks)

Answer 4

1. Coordinates how data moves around the CPU
2. By issuing signals to control the flow of the data / hardware
3. Decodes the instructions fetched from memory

Question 5

What is the cache? What is its function? (3 marks)

Answer 5

1. Very small, very fast memory located in the CPU
2. Used to provide quick access to frequently used instructions and data
3. Stores data to be immediately processed
4. It prevents the CPU from having to repeatedly fetch frequently used instructions from RAM

Question 6

What happens where there is more cache? (2 marks)

Answer 6

1. More cache means more data can be stored
2. Speeds up the performance of the CPU

Question 7

What are registers? (2 marks)

Answer 7

1. Extremely small, extremely fast memory located in the CPU
2. Each register has its very own specific purpose

Question 8

Why is the data not kept in the RAM and collected one at a time to be processed? (5 marks)

Answer 8

1. Cache memory is much closer to CPU
2. Keeps data closer to the CPU 3. Reduces transfer time / makes it quicker
3. Cache memory is temporarily used to hold data and instructions that the processor is likely to reuse
4. Allows for faster processing as processor does not have to wait for the instructions and data to be fetched from RAM (outside the CPU)