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OSY216D 2021 S1 A1 - xxx
OPERATING SYSTEMS III (OSY301T)
Tshwane University of Technology
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OSY216D S1, 2021 Assignment 1
Page 1 of 3
Faculty of Information and Communication
Technology
Department of Information Technology
Operating Systems 226R
OSY216D
Due Date: 21 June 2021 at 13:
SPECIAL REQUIREMENTS : Submit a typped neat report INSTRUCTIONS TO CANDIDATES: Answer all the questions
NUMBER OF PAGES: 3 APPENDIX: 0
COURSE/S: DIPLOMA IN INFORMATION TECHNOLOGY
EXAMINER Dr. M. MIGABO
MODERATOR Mr. N. MATANGA
TOTAL MARKS: 40 FULL MARKS: 40
OSY216D S1, 2021 Assignment 1
Page 2 of 3
Question 1 – Introduction to Operating System [23]
- By means of well-selected examples, explain the two main functions of an operating system. (4)
- Using two examples, differentiate between timesharing and multiprogramming systems. (4)
- Suppose that a 10-MB file is stored on a disk on the same track (track 50) in consecutive sectors. The disk arm is currently situated over track number 100. How long will it take to retrieve this file from the disk? Assume that it takes about 1 ms to move the arm from one cylinder to the next and about 5 ms for the sector where the beginning of the file is stored to rotate under the head. Also, assume that reading occurs at a rate of 200 MB/s. (4)
- Modern operating systems decouple a process address space from the machine’s physical memory. List two advantages of this design. (4)
- Virtual machines have become very popular for a variety of reasons. Nevertheless, they have some downsides. Name one. (1)
- Consider a system that has two CPUs, each CPU having two threads (hyperthreading). Suppose three programs, P0, P1, and P2, are started with run times of 5, 10 and 20 msec, respectively. How long will it take to complete the execution of these programs? Assume that all three programs are 100% CPU bound, do not block during execution, and do not change CPUs once assigned. (5)
- Which of the following instructions should be allowed only in kernel mode? (1) (a) Disable all interrupts. (b) Read the time-of-day clock. (c) Set the time-of-day clock. (d) Change the memory map.
Question 2 – PROCESSES AND THREADS [17]
Draw a diagram showing the three process states of an Operating System. In theory, with three states, there could be six transitions, two out of each state. However, only four transitions are shown. Are there any circumstances in which either or both of the missing transitions might occur? (5)
When an interrupt or a system call transfers control to the operating system, a kernel stack area separate from the stack of the interrupted process is generally used. Why? (4)
If a multithreaded process forks, a problem occurs if the child gets copies of all the parent’s threads. Suppose that one of the original threads was waiting for keyboard input. Now two threads are waiting for keyboard input, one in each process. Does this problem ever occur in single-threaded processes? (4)
OSY216D 2021 S1 A1 - xxx
Course: OPERATING SYSTEMS III (OSY301T)
University: Tshwane University of Technology
