1. What are the three main purposes of an operating system? 2 .We have stressed the need for an operating system to make efficient use of the computing hardware. When is it appropriate for the...

1. What are the three main purposes of an operating system?


2 .We have stressed the need for an operating system to make efficient use


of the computing hardware. When is it appropriate for the operating


system to forsake this principle and to “waste” resources? Why is such


a system not really wasteful?


3. What is the main difficulty that a programmer must overcome in writing


an operating system for a real-time environment?


4. Keeping in mind the various definitions of operating system, consider w
hether the operating system should include applications such as web

browsers and mail programs. Argue both that it should and that it should

n
ot, and support your answers.

5. How does the distinction between kernel mode and user mode function


as a rudimentary form of protection (security) system?


6. Which of the following instructions should be privileged?


a. Set value of timer.


b. Read the clock.


c. Clear memory.


d. Issue a trap instruction.


e. Turn off interrupts.


f. Modify entries in device-status table.


g. Switch from user to kernel mode.


h. Access I/O device.