COMP3231/COMP9201/COMP3891/COMP9283 Operating Systems
Question 1 [40 Marks]
Answer this question on the multiple-choice answer sheet provided.
For each statement given below, classify each statement as true if the statement is generally true, or false
if the statement (or a component of it) is false.
If the statement is true, mark box ‘A’ on the answer sheet provided; if the statement is false, mark box
‘B’. You will receive one mark for each correct classiﬁcation, and lose one mark for each incorrect
classiﬁcation. You gain zero marks for each answer left unclassiﬁed. The overall mark for this question
will not be negative, i.e. the minimum mark is zero.
1) The role of an operating systems is to present all the low level details of the computer hardware
without any abstraction.
2) The operating system runs in the privileged mode of the microprocessor.
3) An application running in user-mode shares the same stack with the operating system when it runs
in kernel mode.
4) An operating system can enforce security by putting checks in the standard C-library.
5) Arguments to system calls are placed in registers (or on the stack) based on a mutually deﬁned
convention between the OS and user-level applications.
6) In the three-state process model, and common transition is from ready to blocked.
7) Co-operative (non-preemptive) multitasking can result in a non-responsive system if an application
has an endless loop.
8) A threading library implementation at user-level (i.e. user-level threads) does not expose the con-
currency available in the application to the operating system.
9) Application threading supported by kernel implemented threads (i.e. kernel-level threads) can take
advantage of multiple processors if available.
10) Applications (i.e. user-level code) can synchronise to avoid race conditions by disabling and en-
11) Semaphores can be used to implement mutual exclusion primitives.
12) Condition variables are used together with semaphores to manage blocking and waking within the
13) Bankers algorithm can avoid deadlock if the maximum resource requirements of threads are known
14) Hold and wait is a practical deadlock prevention strategy.
15) Sparse ﬁles save disk space by not storing the parts of the ﬁle that are not written to.
16) The buffer cache improves write performance by buffering writes. Without extra application effort,
the performance increase comes at the expense of reliability and consistency in the presence of
17) Contiguous ﬁle allocation is an allocation strategy suitable for read-only media.
18) Chained (link-list) ﬁle allocation is desirable for ﬁle systems that support random-access workloads.
19) Best-ﬁt memory allocation gives the best result in terms of memory fragmentation.
20) Swapping allows applications larger than physical memory to execute.
21) Overlays allow applications larger than physical memory to execute.
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