29 List five services provided by an operating system and explain how each

29 list five services provided by an operating system

This preview shows page 5 - 7 out of 9 pages.

2.9 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. Answer: The five services are: a. Program execution . The operating system loads the contents (or sections) of a file intomemory and begins its execution.Auser-level program could not be trusted to properly allocate CPU time. b. I/O operations .Disks, tapes, serial lines, and other devicesmust be communicated with at a very low level. The user need only specify the device and the operation to perform on it, while the system converts that request into device- or controller-specific commands. User-level programs cannot be trusted to access only devices they Practice Exercises 7 should have access to and to access them only when they are otherwise unused. c. File-system manipulation . There are many details in file creation, deletion, allocation, and naming that users should not have to perform. Blocks of disk space are used by files andmust be tracked.
Image of page 5