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Quiz1 on Chapter 1 and Chapter 2.
Operating Systems and Networking.
1. What are the objectives of modern commodity level operating systems? Classify these objectives
from two divergent sets of interests: (a) from the perspective of view of user needs, and (b) from
the perspective of system needs. Suggest why such polarized accounting may be necessary.
2. Operating system is supposed to provide easy interfaces to hardware. What are in hardware that
OS needs to present consistently to user programs?
3. CPU registers are essential to provide operational links between CPU, process, and I/O processor.
Show how.
4. I/O could be done most optimally using the DMA system. What is the DMA system, and how does
it work?
5. I/O could be done using (a) programmed-I/O approach and (b) interrupt driven approach. How
do they work? In what way DMA represents a totally different paradigm compared to these two
modes of getting I/O done?
6. What is the difference between and interrupt and a trap? What happens if a user on getting the
system disables interrupt?
7. How should we deal with multiple interrupts? Discuss various approaches to it.
8. Discuss what CPU must do (a) when the current process exits it, (b) when it has to respond to an
interrupt, or (c) the triggering event is a trap.
9. An OS could appear in different architectural modes like monolithic, layered, objected oriented
and as a micro-kernel. Indicate their basic design principles outlining their weaknesses and
10. What are open systems? Why is the trend toward open systems so strong? What effect will open
systems have on the massive installed bases of proprietary hardware, software and
communication systems?
11. What would be in your opinion the three main features of memory? In what way(s) cache
memory is different than, say, RAM memory?
12. What is the purpose of a system call? How do the system calls relate to the underlying operating
system and to the concept of dual-mode (kernel-mode and user-mode) operations?
13. One of the cited appeals of a microkernel based operating systems is flexibility. Explain how
architectural ‘flexibility’ does allow one to implement a more adaptive platform for user
14. One famous OS designer suggests two types of cache configurations in multi-core chips as
shown below in figures (a) and (b)
Suggest under what condition configuration (a) would be preferable to that of (b)? Under what
conditions the reverse would be true?
15. Symbian and Palm OS are popular OS for handheld computers as Tanenbaum indicates on page
35. In what major ways, does a handheld OS differ from PC based OS? Tanenbaum mentions
lack of hard drive capacity in handheld computers. What else are worth noting?
16. What is a PCB block? What does it contain? Why is it important? Who needs it? What if it is
accidentally lost? Could it be regenerated somehow in case it’s lost?
17. Explain the way they do differ from each other. Briefly evaluate each system from (a)
performance, and, (b) the security points of view.
18. What are the differences and similarities between a multiprogramming system and a timesharing
system in a multiuser environment? What would be the most likely systems objective in each
19. In an operating system context, system performance could be measured using one or more of
the following metrics. Explain their meaning and their relevance as possible performance
measures in specific system environment
Residence time
Response time
Turnaround time
20. What does it mean for a process to be preemptive? What does it mean to be nonpreemptive?
Can the processor handle interrupts while a nonpreemptive process is running? Explain. Give an
example of a process that might be preemptive. What type of processes would probably
21. In a time-sharing system, a process might be temporarily deprived of CPU. Indicate those cases
in which such possibilities might result. What must OS require of CPU to do to facilitate a smooth
transition for the target process? What happens to the process if the departure is necessitated by
an (a) I/O call, or, by a (b) system error?
22. In virtually all systems that include DMA units, DMA access to main memory is given higher
priority than processor access to main memory. Why?
23. What is the difference between a batch system and an interactive system? When you pay your
grocery bill by a credit card instead of cash, what system would you be using? What is the
system objective to attain in a multiprogramming system? What is the corresponding goal in a
time-sharing system.
24. What is context switching? Under what conditions does a context-switch take place? What must
be done when a context-switch is warranted?
25. Real-time computing is often misunderstood to be high-performance computing. Give an example
to show that it is not always true. Could a network server, highly loaded with network traffic, be
considered a real-time system element? Why, or, why not? Indicate why, for a real-time system,
the predictability and not performance is the pertinent issue.