The purpose of the CPU questions and answers
Q1. What does ‘CPU’ stand for?
A1. Central Processing Unit
Q2. Describe briefly what is meant by the ‘fetch – decode – execute’ cycle.
A2. Fetching an instruction from memory, deciding what the instruction means, then carrying out the instruction.
Q3. A CPU might execute an ‘arithmetic instruction’ or ‘a logical instruction’. Describe with an example what the difference is between an arithmetic instruction and a Boolean instruction.
A3. Arithmetic = add, subtract, multiply, divide e.g. 3 + 5. Logical AND, OR, NOT e.g. 110 AND 011 gives 010.
Q4. Define software.
A4. Software is the term for the instructions and programs that make the hardware do useful things.
Q5. Where does the CPU fetch instructions from?
A5. The CPU fetches instructions from Random Access Memory (RAM).
Q6. Where are all programs and files kept, whether they are being used or not?
A6. They are all kept on the hard drive.
Q7. What is meant by 'decoding' and instruction?
A7. Decoding an instruction means working out what the instruction is and what has to be done next to carry it out.
Q8. What is the next part of the cycle after decoding an instruction?
A8. Once an instruction has been decoded, it is executed.
Q9. What carries signals such as address, data and control signals around the computer between components?
A9. Busses carry signals between components.
Q10. Some processors are known as 'quad core'. What does this mean?
A10. Quad core means that the processor is in fact made up of four smaller processors.