COP 4610 - Operating Systems questions well answered to pass, Exams of Nursing

Download COP 4610 - Operating Systems questions well answered to pass and more Exams Nursing in PDF only on Docsity! COP 4610 - Operating Systems Operating System (OS) - correct answer ✔✔Software that runs on the bare hardware of a computer and provides essential support for users to develop and use applications in the most efficient and safe manner. Abstraction - correct answer ✔✔The act of removing unimportant details or attributes of objects in order to construct more general and less complex objects. OSs make extensive use of abstraction by creating hierarchies of objects where multiple operations at one level are combined into a single operation at a higher level, thus hiding the details of the implementation and making the operation easier to use. Virtualization - correct answer ✔✔The act of creating virtual (rather than physical) versions of a variety of computing capabilities including hardware platforms, Operating Systems, Storage Devices, and Networks. The act of creating the illusion of having one or more objects with more desirable characteristics than the real object. OSs rely on virtualization to create virtual CPUs, memory, I/O devices, and other system components that facilitate the work of programmers and users. Abstraction vs Virtualization - correct answer ✔✔Are closely related. Abstraction emphasizes unification and simplification by combining multiple simpler objects into more complex ones. Virtualization may use abstraction, but emphasizes diversification and replication by creating illusions of objects with more favorable characteristics. An OS is thus an extended machine, which provides efficient high-level functions and virtual entities that liberate the programmer and the user from having to understand details of memory, disk, I/O management, and other internal processes. Multiprogramming - correct answer ✔✔A technique that keeps several programs active in memory and switches execution among the different programs to maximize the use of the CPU and other resources. Whenever a program enters an I/O-bound phase where little CPU time is needed, other programs can resume and utilize the CPU in the meantime. Similarly, whenever a device completes an operation, the OS activates computations that can utilize the now available device. Time-sharing (multitasking) - correct answer ✔✔An extension of multiprogramming where the CPU is switched periodically among all active computations to guarantee acceptable response times to each user. Time-sharing employs the concept of virtualization by creating the illusion of having a separate virtual CPU for each computation. Justify or refute: Abstraction can be used without virtualization. - correct answer ✔✔Abstraction does not necessarily create a virtual object. EX: A single operation to read n bytes from a file is implemented as a sequence of many low-level instructions. The new operation is not a virtual version of any physical object. Justify or refute: Virtualization can be used without abstraction. - correct answer ✔✔Virtualization creates the illusion of a new object, but the new object can have exactly the same characteristics as the underlying physical object. No features have been removed or simplified. EX: The OS can create the illusion of having multiple printers, one per user, but each of the virtual printers is identical to the physical printer. Justify or refute: Abstraction and virtualization can be used together. - correct answer ✔✔A virtual object is frequently simpler than the underlying physical object by having fewer features and a higher-level interface created by abstraction. The OS can provide the illusion of a simple local storage device, which is implemented in a distributed manner by managing the stored data on remote network servers. The user is unaware of the internal implementation. What do multiprogramming and time-sharing have in common? What are differences between the two concepts? - correct answer ✔✔Multiprogramming allows multiple programs to be active in memory simultaneously. While one is waiting for I/O completion or some other event, another can run on the CPU. The main objective is to increase CPU and device utilization. Time sharing goes beyond multiprogramming by guaranteeing that each computation gets a turn at the CPU in a timely manner, not only when other computations block. Kernel - correct answer ✔✔The kernel of an OS is the minimal set of functions necessary to manage the system resources safely and efficiently. The kernel typically provides the most essential services for