Question 1
Choose the correct answer
1- The main function of the operating system is to provide an interface between ………… and application
programs used by users.
[ ] Software [ ] Hardware [ ] Networks [ ] Application
2- ……… program is loaded at power-up or reboot.
[ ] Kernel [ ] Bootstrap [ ] Computer [ ] Application
3- Software may trigger an interrupt by executing a special operation called a ………
[ ] System processes [ ] Database [ ] System call [ ] None of the above
4- ……… any mechanism for controlling access of processes or users to resources defined by the OS.
[ ] Supervisor [ ] Security [ ] Networks [ ] Protection
5- ……… time is the amount of time it takes from when a request was submitted until the first
response is produced, not output.
[ ] Waiting [ ] Turnaround [ ] Response [ ] None of the above
6- ……… scheduler chooses from ready queue a job to run on CPU.
[ ] Short-term [ ] Long-term [ ] Medium-term [ ] None of the above
7- ……… consists of everything below the system-call interface and above the physical hardware.
[ ] The software [ ] The kernel [ ] The system [ ] None of the above
8- ……… time it takes for the dispatcher to stop one process and start another running.
[ ] Throughput [ ] Dispatcher [ ] Dispatch latency [ ] Turnaround
9- Timesharing (multitasking) is logical extension in which CPU switches jobs so frequently that
users can interact with each job while it is running, creating interactive computing.
[ ] Scheduler [ ] Single task [ ] Preemptive [ ] Multitasking
10- In CPU scheduling, FCFS is stands for First-Come, ………….
[ ] Fast-Served [ ] First-Send [ ] First-Served [ ] None of the above
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Question 2
State True or False and correct the false statements
1- Mostly accessed by programs via a high-level Application Programming Interface [ T ]
(API) rather than direct system call use.
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2- Bootstrap program is loaded at power-up or reboot. [ T ]
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3- Small, fast memory located between the processor and main memory is called WORM [ F ]
memory.
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4- Virtualization is a technology that allows operating systems to run as applications [ T ]
within other operating systems.
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5- Communications provide the mechanism for creating virtual connections among [ T ]
processes, users, and computer systems.
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6- Cloud computing delivers computing, storage, even apps as a service across a network [ T ]
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7- Throughput is to keep the CPU as busy as possible. [ F ]
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8- In preemptive, once a process is allocated the CPU, it does not leave until terminate. [ F ]
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9- Medium-term scheduler may move (swap) some partially-executed jobs from memory [ T ]
to disk (to enhance performance).
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10- CPU utilization is to keep the CPU as busy as possible. [ T ]
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Question 3
The following figure is VMware architecture:
Determine the host operating system(s) and the guest operating system(s)?
host operating system is Linux
guest operating systems are (free BSD, Windows NT, Windows XP)
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Question 4
In CPU scheduling, what the different between turnaround time, waiting time, and response time?
• Turnaround time – amount of time to execute a particular process. (time
from submission to termination)
• Waiting time – amount of time a process has been waiting in the ready
queue.
• Response time – amount of time it takes from when a request was submitted
until the first response is produced, not output.
Question 5
Explain two of the operating system services?
User interface - Almost all operating systems have a user interface (UI).
Program execution - The system must be able to load a program into memory
and to run that program, end execution, either normally or abnormally
(indicating error).
I/O operations - A running program may require I/O, which may involve a file
or an I/O device.
File-system manipulation – The file system is of particular interest. Programs
need to read and write files and directories, create and delete them, search
them, list file Information, permission management.
Communications – Processes may exchange information, on the same
computer or between computers over a network.
Error detection – OS needs to be constantly aware of possible errors.
Resource allocation - When multiple users or multiple jobs running
concurrently, resources must be allocated to each of them.
Accounting - To keep track of which users use how much and what kinds of
computer resources.
Protection and security - The owners of information stored in a multiuser or
networked computer system may want to control use of that information,
concurrent processes should not interfere with each other.
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Question 6
Using a preemptive SJF scheduling algorithm. Consider the following processes with the relative CPU
bursts.
Process Arrival Time Burst Time
P1 0 7
P2 1 3
P3 3 5
Draw the Gantt charts, and find out the average waiting time.
Process Waiting Time
P1 9−1=8
P2 1−1=0
P3 4−3=1
average waiting time = (8+0+1)/3 = 3 ms
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