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OPS621S - OPERATING SYSTEMS - 2ND OPP - JAN 2025 |
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nAm I BIA un IVERSITY
OFSCIEn CE Ano TECHn OLOGY
Faculty of Computing and Informatics
QUALIFICATION : BACHELOROF COMPUTER SCIENCE: SYSTEMSADMINISTRATION, COMMUNICATION
NETWORl<S;BACHELOROF SOFTWAREDEVELOPMENT,BACHLOEROF GEO-INFORMTION TECHNOLOGY
QUALIFICATIONCODE: 80BSAN; 07BACS,07BGEI
LEVEL: 6
COURSE: OPERATINGSYSTEMS
COURSECODE: OPS621S
DATE: JANUARY2025
SESSION: 2
DURATION: 3 HOURS
MARKS: 70
SECONDOPPORTUNITY/SUPPLEMENTARYEXAMINATION QUESITON PAPER
EXAMINER(S)
ALBERTINASHILONGO
MODERATOR:
LOINI IIYAMBO
INSTRUCTIONS
1. Answer ALL the questions.
2. Read all the questions carefully before answering.
3. Number the answers clearly
THIS QUESTIONPAPERCONSISTSOF 5 PAGES
(including this front page)
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Multiple Choice and Fill in question/True and False: Writhe the question number and the correct
answer next to it.
[20 Marks]
1. Which OS is pre-emptive processing and put high significance on priority processing.
a) Batch OS
b) Real-Time OS
c) Network OS
d) Distributed OS
2. Which is an example of an embedded operating system?
a) Windows 10
b) Android
c) FreeRTOS
d) Ubuntu
3. Which term correctly describe fragmentation in memory management?
a) Misuse of CPU usage
b) Inefficiency usage of memory space due to dynamic allocation leading to memory
space wastage.
c) Loading programs into memory.
d) The speed at which d.ata is transferred from the processor to memory.
4. Which of the following correctly explain "swapping" in memory management?
a) Copying files to disk
b) Moving processes between main memory and virtual memory.
c) Changing the file permission to read.
d) More memory space the process in memory management.
5. Which tern explain the techniques used in memory management to divides memory into
fixed-size blocks?
a) Paging
b) Segmentation
c) Compaction
d) Virtual Memory
6. Which term correctly describe page fault in Memory management.
a) When a page is 11otfound in the main ,:nemory.
b) An error in memory allocation.
c) Incorrectly data written a memory page
d) Misuse of page table.
7. What is the primary function of virtual memory?
a) Faster access to data.
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b) It offers the ability to the OSto cater for processes larger than the Main memory can
accommodate.
c) Simplifies the operation memory management.
d) Efficiency in power consumption.
8. What is a process in OS?
a) A collection of running programs.
b) An instance of a program that is running.
c) A technique used to manage memory management.
d) scheduling of tasks.
9. What does the term scheduling refers to in process management?
a) Processallocation to memory pages.
b) Technique applied by the OS in determining the the order in which processes are
executed.
c) Configuration of processes.
d) Processallocation to CPU.
10. The read state of a process indicates that ....
a) The process is currently under execution.
b) The process is waiting for an event to occur prior execution.
c) The process is waiting for CPUtime.
d) The process has completed its execution.
Fill in the missing words:
11. A specialized software that enables the OS and hardware peripheral component to
communicates is a ----------
12. A/an _______
is a signal from hardware or software indicating that there is an
event that in the computer that requires immediate attention.
13. __________
is a nonprimitive scheduling algorithm that handles incoming in
the order they arrive in the ready.
14. A(n) ________
contains files with the names of users who are allowed to
access it and the type of access each user is permitted.
15. ________
are resources that can be taken away from active process and
reallocated to another process in the ready queue.
Determine whether the following statements are true or false:
16. File management includes creating, editing, moving, and deleting files on a computer
system:
17. Operating system security is mainly concerned with protecting the system from
unauthorised access and threats.
18. Least Recently Used algorithm (LRU)works on the assumption that the most recently used
page is likely not to be requested back in the RAM.
19. Regular software updates are critical in the maintained of the OS security and protecting
against system vulnerabilities.
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20. Round Robin scheduling algorithm function on process priority basis.
Sectio B: Short questions
[20 Marks]
1. List and explain any four goals that describe good scheduling policy in process
management?
(8)
2. Explain the master file directory (MFD) and state its role.
(4)
3. Explain the difference between shared and virtual devices. Give one (1) example of each
device.
(4)
4. Explain the difference between the following concepts used in operating systems.
a. Aging
(2)
b. Context Switching
(2)
Section C: Practical
Question 1
[30 Marks]
You are given that it takes 1.5 ms to travel from one track to the next, and that the read/write arm
is originally positioned at Track 350. The request queue (number of tracks) is 0-700. (Ignore
rotational time and transfer time, just consider seek time). You must note that the read/write arm
by default moves towards the high-numbered tracks.
Compute how long it will take to satisfy the following track requests which are all present in the wait
queue:
427, 118, 610, 105, 274, 77, 555
1.1 Use the following seek strategy algorithms, illustrate using a graph how
the track requests will be serviced.
a) SSTF
(5)
b) LOOK
(5)
1.2 Calculate the average seek time for both seek strategies mentioned in 1.1.
a) SSTF
(2)
b) LOOK
(2)
Question 2
2.1 In demand paging, a page replacement policy is used to manage system resources. Given that
main memory has 4-page frames available to programs and that a program consisting of 15 pages is
to be loaded in main memory. The request pages are provided below in order:
10 2143 10 204 3124
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Suppose that all the page frames are initially empty.
a) Using the following Least Recently Used (LRU)removal algorithms, demonstrate how you will
fit the pages in the frames
(8)
b) Calculate the hit rate and page fault.
(2)
Question 3:
3.1 Suppose You are given the following memory blocks of size in (MB): {150, 350, 500, 200, 300}.
The following processes require the indicated memory size (MB) need to be allocated.
• Process 1:120
• Process 2: 300
• Process 3: 180
• Process 4: 490
• Process 5:560
a) Using the Best Fit Memory allocation indicate the memory blocks that will be allocated.
(5)
b) Calculate the total memory fragmentation that will occur.
(1)
Exam Ends