Von Neumann, Harvard and contemporary processor architecture

Question 1

What is Von Neumann architecture?

Answer 1

• Includes the basic components of the computer and processor
• Shared memory and shared data bus is used for both data and instructions
• Built on the stored program concept

Question 2

Where is Von Neumann architecture more commonly used?

Answer 2

• Personal computers

- Small computers

Question 3

Advantages of Von Neumann architecture?

Answer 3

• Cheaper to develop as the control unit is easier to design

- Programs can be optimised in size

Question 4

Disadvantages of Von Neumann architecture?

Answer 4

• Parallel executions of programs are not allowed due to serial instruction processing
• Only one “bus” can be accessed at a time, this results in the CPU being idle - Von Neumann Bottleneck

Question 5

What is the Harvard architecture?

Answer 5

• Physically separate memories for instructions and data

- Useful for when memories have different characteristics

Question 6

Where is Harvard architecture more commonly used?

Answer 6

• Micro controllers

- Signal processing

Question 7

Advantages of Harvard architecture?

Answer 7

• Quicker execution as data and instructions can be fetched in parallel.
• Memories can be different sizes, which can make more efficient use of space

Question 8

Disadvantages of Harvard architecture?

Answer 8

• More complex architecture, as it requires two buses, more time to manufacture/more expensive
• The un-occupied data memory cannot be used by instructions and the free instruction memory cannot be used by data. Memory dedicated to each unit has to be balanced carefully

Question 9

What is contemporary processor architecture?

Answer 9

• Use a combination of Von Neumann and Harvard architecture
• Von Neumann is used when working with data and instructions in main memory
• Harvard architecture to divide the cache into instruction cache and data cache