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CORK INSTITUTE OF TECHNOLOGY
INSTITIÚID TEICNEOLAÍOCHTA CHORCAÍ
Semester 2 Examinations 2009/10
Module Title: Operating Systems Fundamentals
Module Code: SOFT 6003
Programme Title: B.Sc. (Honours) in Software Development and Computer Networking
Higher Certificate in Science in Information Technology Support
Programme Code: KITMN_8_Y1
External Examiner(s): Mr. Ken Carroll
Internal Examiner(s): Mr Ger MacSweeney
Ms Helen Fagan
Instructions: Answer four questions. Show all work.
Duration: 2 hours
Sitting: Summer 2010
Requirements for this examination:
Note to Candidates: Please check the Programme Title and the Module Title to ensure that you have received the
correct examination paper.
If in doubt please contact an Invigilator.
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i) What are the main goals of a modern Operating System? List four of the main modules found
in an Operating System.
ii) What is an interrupt and why is this mechanism used by the CPU?
iii) With the aid of a diagram, describe the ‘fetch-execute’ cycle indicating when
interrupts are handled.
iv) Explain in detail the steps that are followed when an interrupt occurs.
i) Draw a 5 state Process Transition Diagram naming all states and illustrating the transitions
between these states.
ii) Apart from normal completion, suggest three reasons why a process might terminate.
iii) Consider the following set of processes with arrival times and service times given in
Process Name Arrival
A 0 2
B 2 6
C 4 3
D 5 1
Draw a timeline to show the execution of each of these processes for the following scheduling
• Round Robin - time slice (quantum) = 1.
• Shortest Remaining Time
Calculate the turnaround and the normalised turnaround time for each process.
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i) Describe how Fixed Partitioning and Dynamic Partitioning may be used to manage
memory. Explain when or if internal and external fragmentation occur in each case.
ii) Explain how a program is loaded into memory when a paging scheme is used for memory
management. Why is paging a better memory management solution than Dynamic
iii) Convert the following 16-bit logical address into the 16-bit physical given the 6-bit page
number and 10-but offset and using the supplied process page table
Process Page Table
i) With the aid of a diagram, briefly describe the structure of a hard disk and explain the terms
seek time, latency, and transfer time.
ii) What are the main differences between the C-Scan and SSTF algorithms used in Disk
iii) For the following track request queue, calculate the head movement for the
SSTF and the C-Scan algorithm.
Assume that the head starts at track 152 and is moving toward track 199. Also assume that the
drive has 200 tracks numbered 0-199.
Request queue: 86, 147, 91, 177, 94, 150, 102, 175, 130 [6 marks]
iv) Explain what is meant by I/O Buffering . What is the advantage of Double Buffering
over Single Buffering.
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i) Name three ways a disk management system might keep track of free space.
ii) With the aid of a diagram, describe the UNIX block addressing scheme. In your answer,
explain what is meant by:
• An i-node
• Single indirect addressing
• Double indirect addressing
• Triple indirect addressing
iii) Why is the scheme suitable for both large and small file?
iv) If the length of a block is 1Kbyte and each block that acts as an index block can hold 256
block addresses calculate the maximum size of a file. Show how you derived your answer.