A Level Computer Science OCR Practice Exam

What is the major difference between Von Neumann Architecture and Harvard Architecture?

1. Von Neumann uses multiple control units

2. Harvard has shared data pathways

3. Von Neumann has combined instruction and data storage

4. Harvard has a linear control flow

The correct answer is: Von Neumann has combined instruction and data storage

The choice highlighting that Von Neumann architecture has combined instruction and data storage is correct because this architecture utilizes a single memory for both program instructions and data. This contrasts with Harvard architecture, which features separate memory storage for instructions and data, allowing for simultaneous access to both and potentially leading to improved performance. The integration of instruction and data storage in Von Neumann architecture means that there can be contention for the memory bus, as both instructions and data must share the same pathways for processing. This characteristic fundamentally shapes how programs operate within this architecture, influencing design and performance considerations. In addition, while the other choices mention characteristics that do not accurately describe the architectures, they serve to highlight key distinctions. For example, Harvard architecture is known for having separate pathways, which facilitates parallel processing of instructions and data, whereas Von Neumann's unified approach can result in bottlenecks. Understanding these structural differences is essential for grasping the performance implications of each architecture.