Describe the process of segmentation for memory management.

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2024). The mark or mark type is shown in brackets.

1. 8(a) One mark per mark point (Max 4)
2. 8(a) MP1 In segmented memory, the logical / virtual address space is broken into varying sized blocks called segments / sections.
3. 8(a) MP2 Each segment has a name and size.
4. 8(a) MP3 During execution segments from logical / virtual memory are loaded into physical memory.
5. 8(a) MP4 The address is specified by the user
6. 8(a) MP5 it contains the segment name and offset value.
7. 8(a) MP6 Segments are numbered
8. 8(a) MP7 and this number is used as an index in the segment map table.
9. 8(a) MP8 The offset value determines the size of the segment.
10. 8(a) MP9 A segment map table maps logical / virtual addresses to physical addresses / contains the segment number and offset.
11. 8(b) One mark per mark point (Max 3)
12. 8(b) MP1 Disk thrashing is a problem that may occur when virtual memory is being used.
13. 8(b) MP2 As the main memory fills up, more and more pages need to be swapped in and out of virtual memory.
14. 8(b) MP3 This swapping leads to a very high rate of hard disk access / excessive disk head movements.
15. 8(b) MP4 Moving a hard disk read/write head takes a relatively long time / long latency time.
16. 8(b) MP5 Eventually, more time is spent swapping pages than processing data thrash point, which can cause the program to freeze or not run.