文档介绍：solutions to the exercises
Chapter 1
In a multiprogramming and time-sharing environment, several users share the system simultaneously. This situation can result in various security problems.
a. What are two such problems?
b. Can we ensure the same degree of security in a time-shared machine as in a dedicated machine? Explain your answer.
Answer:
a. Stealing or copying one’s programs or data; using system resources (CPU, memory, disk space, peripherals) without proper accounting.
b. Probably not, since any protection scheme devised by humans can inevitably be broken by a human, and the plex the scheme, the more difficult it is to feel confident of its correct implementation.
The issue of resource utilization shows up in different forms in different types of operating systems. List what resources must be managed
carefully in the following settings: a. Mainframe or puter systems b. Workstations connected to servers c. puters
Answer:
a. Mainframes:memory and CPU resources, storage, network bandwidth.
b. Workstations: memory and CPU resouces
c. puters: power consumption, memory resources.
Under what circumstances would a user be better off using a timesharing system rather than a PC or single-user workstation?
Answer: When there are few other users, the task is large, and the hardware is fast, time-sharingmakes sense. The full power of the system can be brought to bear on the user’s problem. The problemcan be solved faster than on a puter. Another case occurs when lots of other users need resources at the same time.
A puter is best when the job is small enough to be executed reasonably on it and when performance is sufficient to execute the program to the user’s satisfaction.
Which of the functionalities listed below need to be supported by the operating system for the following two settings: (a) handheld devices and (b) real-time systems. a. Batch programming b. Virtual memory c. Time sharing
Answer: For real-time systems, the operatin