Computer Science
Processor architecture and memory
- 1.
Describe the roles of the program counter and memory address register during instruction fetch.
[3 marks] · no calculator - 2.
Explain why RAM and secondary storage serve different roles when running a program.
[3 marks] · no calculator - 3.
A cache lookup takes 2 ns. On a miss, an additional 50 ns memory access is needed. With hit rate 0.90, calculate mean access time under this nonoverlapping model.
[3 marks] - 4.
Explain how temporal and spatial locality can make a cache effective in a loop processing consecutive array elements.
[3 marks] · no calculator - 5.
A program spends 60% of its original time in a section sped up by a factor of 3; the rest is unchanged. Calculate overall speedup and explain the bottleneck limit.
[4 marks] - 6.
An interrupt occurs while a user program is executing. Explain the state-saving and return requirements, and why disabling all interrupts permanently would not be a satisfactory solution to interruption overhead.
[4 marks] · no calculator
Marking points are indicative, not an official mark scheme. Accept equivalent valid methods and supported interpretations that address the task; award each mark once without requiring the model wording.