Answer any four questions from the list below:

1- What is the purpose of interrupts? How does an interrupt differ from a trap? Can traps be generated intentionally by a user program? If so, for what purpose?

2- Describe some of the challenges of designing operating systems for mobile devices compared with designing operating systems for traditional PCs.

3- List five services provided by an operating system, and explain how each creates convenience for users. In which cases would it be impossible for user-level programs to provide these services? Explain your answer.

4- Explain the role of the init (or systemd) process on UNIX and Linux systems in regard to process termination.

5- What are two differences between user-level threads and kernel-level threads? Under what circumstances is one type better than the other?