A Level Computer Science OCR Practice Exam

How does paging differ from segmentation?

1. It uses fixed sizes for data storage

2. It allows dynamic sizes for data storage

3. It only stores executable code

4. It is always faster than segmentation

The correct answer is: It allows dynamic sizes for data storage

Paging and segmentation are both memory management techniques used by operating systems, but they have fundamental differences in how they handle memory allocation. The correct choice highlights that paging allows for fixed-size blocks of memory, usually referred to as pages. Each page is the same size, which means that when a process is loaded into memory, it is divided into these fixed-size pages that are then mapped to physical memory. This uniformity simplifies memory allocation and management. Segmentation, on the other hand, permits dynamic sizes for segments. In segmentation, a program is divided into different segments that can vary in size, such as code, data, stack, or heap. Each of these segments can grow or shrink independently based on the needs of the program, allowing for more flexible memory usage that reflects the logical divisions of a program. The other options do not accurately capture the distinctions. For example, stating that paging is always faster than segmentation overlooks the complexity of the context and the actual overhead that can occur with both methods. Similarly, mentioning that paging only stores executable code or has fixed sizes for data storage does not reflect the full capabilities and flexibility inherent in these memory management strategies.