Von Neumann: exam style questions

1. Explain what is meant by the term "Von Neumann Architecture" (2 marks)

A computer where both the data and software currently being used (1) are stored in computer memory (1)

2. What term can be used in place of von Neumann Architecture? (1 mark)

Stored program

3. Give two features of the Von Neumaan architecture (2 marks)

There is enough memory available to hold both programs and data. This makes it easy to change task by loading a different program. In modern computers this memory is RAM. There is a Control Unit responsible for handling the movement of instructions and data around the computer. Data and instructions are carried on buses. There is an Arithmetic Logic Unit responsible for carrying out calculations and logic comparisons. The Accumulator is a special register that holds temporary data as the program runs. There may be many more registers also available. Some have a specific purpose and others are for general use. There is a way of inputting data into the computer and a way to output information.

4. Outline the role of the ALU in the von Neumann architecture (2 marks)

The role of the ALU is to carry out calculations (1) and logic comparisons (1)

5. Identify which part of the CPU holds the address of the next instruction in memory (1 mark)

Program counter

6. Outline the role of the program counter (2 marks)

It holds the address of the current instruction (1) and updates the MAR with the address of the next one.(1)

7. Identify what it is that controls the program counter (1 mark)

The software that is currently running in RAM

8. Explain why the program counter doesn't always increment instruction numbers by one (2 marks)

It may receive a branch instruction from the running software (1) telling it to jump to a different point.(1)

9. Outline the role of the accumulator in von Neumann architecture (2 marks)

Holds temporary data (1) while the program runs (1)

10. Explain why data is held temporarily in the accumulator, rather than simply accessing it from RAM. (1 mark)

The Accumulator is much quicker to access than RAM, since it is inside the CPU itself.