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There are three principles of OOP short definations

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EncapsulationInheritancePolymorphism Encapsulation is the mechanism that binds together code and the data it manipulates and keeps both safe from outside interference and misuse.  Inheritance is the process by which one object acquires the properties of another object. By use of inheritance, an object would need only to define those qualities that make it unique within […]

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DEADLOCKS and METHODS FOR HANDLING DEADLOCKS in OS

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In a multiprogramming environment, several processes may compete for a finite number of resources. A process requests resources; if the resources are not available at that time, the process enters a waiting state. Coming to definition Sometimes, a waiting process is never again able to change state, because the resources it has requested are held by […]

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PAGE REPLACEMENT ALGORITHMS in OS

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PAGE REPLACEMENT ALGORITHMS In general, we want a page replacement algorithm with the lowest page-fault rate. We evaluate an algorithm by running it on a particular string of memory references and computing the number of page faults on that string. To determine the number of page faults for a particular reference string and page replacement […]

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BASIC ELEMENTS OF COMPUTER

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BASIC ELEMENTS OF COMPUTER BASIC ELEMENTS OF COMPUTER A computer consists of the processor, memory, and I/O components, with one or more modules of each type. These components are interconnected in some fashion to achieve the main function of the computer, which is to execute programs. Thus, there are four main structural elements: 1.      Processor: […]

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Cache memory

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Although cache memory is invisible to the OS, it interacts with other memory management hardware. Furthermore, many of the principles used in virtual memory schemes  are also applied in the cache memory. On all instruction cycles, the processor accesses memory at least once, to fetch the instruction, and often one or more additional times, to […]

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THREADS IN OPERATING SYSTEM

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A thread is a basic unit of CPU utilization; it comprises a thread ID, a program counter, a register set, and a stack. It shares with other threads belonging to the same process its code section, data section, and other operating-system resources, such as open files and signals. Threads share the memory and the resources […]

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PROCESS STATE

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PROCESS STATE The state of a process is defined in part by the current activity of that process. As a process executes, it changes state. A process may be in one of the following states: 1.      New. The process is being created. 2.      Running. Instructions are being executed. 3.      Waiting. The process is waiting for […]

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Dijkstra’s Algorithm

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Dijkstra’s algorithm is an algorithm for finding the shortest paths between nodes in a graph, which may represent, for example, road networks. It was conceived by computer scientist Edger W. Dijkstra in 1956 The algorithm exists in many variants; Dijkstra’s original variant found the shortest path between two nodes, but a more common variant fixes a single node as the “source” node and finds shortest paths […]