OPERATING SYSTEMS EXAM I WITH
ANSWER KEY PROVIDED WITH 100%
CORRECT ANSWERS
operating system - ANS-a layer of software that manages a computer's resources for its
users and their applications
Resource - ANS-a physical or virtual entity that can be assigned to a user or application.
Virtualization - ANS-provide an application with the illusion of resources that are not
physically present
Protection - ANS-the isolation of potentially misbehaving applications and users so that
they do not corrupt other applications or the operating system itself
Security - ANS-a computer's operation cannot be compromised by a malicious attacker
Privacy - ANS-data sorted on a computer is only accessible to authorized users
principle of least privilege - ANS-system security and reliability are enhanced if each
part of the system has exactly the privileges it needs to do its job and no more
proprietary system - ANS-a system that is under the control of a single company; it can
be changed at any time by its provider to meet the needs of its customers
open system - ANS-a system whose source code is available to the public for
modification and reuse, or a system whose interfaces are defined by a public standards
process
batch operating system - ANS-an early tupe of operating system that efficiently ran a
queue of tasks. While one program was running, another was being loaded into
memory.
time-sharing operating system - ANS-an operating system designed to support
interactive use of the computer
, virtual machine - ANS-an execution context provided by an operating system that
mimics a physical machine, e.g., to run an operating system as an application on top of
another operating system
host operating system - ANS-an operating system that provides the abstraction of a
virtual machine, to run another operating system as an application
guest operating system - ANS-an operating system running in a virtual machine
Overhead - ANS-the added resource cost of implementing an abstraction versus using
the underlying hardware resources directly
Efficiency - ANS-the lack of overhead in implementing an abstraction
response time - ANS-the time for a task to complete, from when it starts until it is done
Throughput - ANS-the rate at which a group of tasks are completed
Utilization - ANS-the fraction of time a resource is busy
Predictability - ANS-whether the system's response time or other metric is consistent
over time.
Reliability - ANS-a property of a system that does exactly what it is designed to do
How does the OS serve as a referee for a parallel application? - ANS-An operating
system manages the resources that applications use on a physical machine. The
operating system is like a referee because it directs what each player (application)
should be doing so that there is a valid game (a correct system state). The operating
system determines which program uses what resources and when. It runs applications
and separates their scope: so that, for example, a bug in one application does not
cause the other to crash. The operating system also defends against outside threats like
viruses.
Is the system library above or below the API? - ANS-The system library sits below the
API.
Describe the Multics system in 2-3 sentences. - ANS-Multics was the first time-sharing
operating system developed by MIT researchers in tandem with General Electric and
Bell Laboratories in the 1960's. New and interesting features at the time were included,
such as: running on a symmetric multiprocessor, using a hierarchical file system, and
providing access control on individual files.
In which role does an OS manage resources, protect users and applications, and
facilitate sharing? - ANS-referee
ANSWER KEY PROVIDED WITH 100%
CORRECT ANSWERS
operating system - ANS-a layer of software that manages a computer's resources for its
users and their applications
Resource - ANS-a physical or virtual entity that can be assigned to a user or application.
Virtualization - ANS-provide an application with the illusion of resources that are not
physically present
Protection - ANS-the isolation of potentially misbehaving applications and users so that
they do not corrupt other applications or the operating system itself
Security - ANS-a computer's operation cannot be compromised by a malicious attacker
Privacy - ANS-data sorted on a computer is only accessible to authorized users
principle of least privilege - ANS-system security and reliability are enhanced if each
part of the system has exactly the privileges it needs to do its job and no more
proprietary system - ANS-a system that is under the control of a single company; it can
be changed at any time by its provider to meet the needs of its customers
open system - ANS-a system whose source code is available to the public for
modification and reuse, or a system whose interfaces are defined by a public standards
process
batch operating system - ANS-an early tupe of operating system that efficiently ran a
queue of tasks. While one program was running, another was being loaded into
memory.
time-sharing operating system - ANS-an operating system designed to support
interactive use of the computer
, virtual machine - ANS-an execution context provided by an operating system that
mimics a physical machine, e.g., to run an operating system as an application on top of
another operating system
host operating system - ANS-an operating system that provides the abstraction of a
virtual machine, to run another operating system as an application
guest operating system - ANS-an operating system running in a virtual machine
Overhead - ANS-the added resource cost of implementing an abstraction versus using
the underlying hardware resources directly
Efficiency - ANS-the lack of overhead in implementing an abstraction
response time - ANS-the time for a task to complete, from when it starts until it is done
Throughput - ANS-the rate at which a group of tasks are completed
Utilization - ANS-the fraction of time a resource is busy
Predictability - ANS-whether the system's response time or other metric is consistent
over time.
Reliability - ANS-a property of a system that does exactly what it is designed to do
How does the OS serve as a referee for a parallel application? - ANS-An operating
system manages the resources that applications use on a physical machine. The
operating system is like a referee because it directs what each player (application)
should be doing so that there is a valid game (a correct system state). The operating
system determines which program uses what resources and when. It runs applications
and separates their scope: so that, for example, a bug in one application does not
cause the other to crash. The operating system also defends against outside threats like
viruses.
Is the system library above or below the API? - ANS-The system library sits below the
API.
Describe the Multics system in 2-3 sentences. - ANS-Multics was the first time-sharing
operating system developed by MIT researchers in tandem with General Electric and
Bell Laboratories in the 1960's. New and interesting features at the time were included,
such as: running on a symmetric multiprocessor, using a hierarchical file system, and
providing access control on individual files.
In which role does an OS manage resources, protect users and applications, and
facilitate sharing? - ANS-referee
