Type of Operating System

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 Operating Systems: 

DOS

Windows Based 

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Operating System

Thread

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  Thread:   A thread, also called a lightweight process (LWP).  A thread is a stream of execution throughout the process code having its program counter which keeps track of lists of instruction to execute next, system registers which bind its current working variables. Threads are also termed as lightweight process. A thread uses parallelism which provides a way to improve application performance.     It is the basic unit utilization of Microprocess.     It has its own program counter, a register set, and stack space.   It shares with the pear threads its code section, data section, and OS resources such as open files and signals, collectively called a task. ·          The idea of a thread is that a process has five fundamental parts: code (“text”), data, stack, file input/output and signal tables. “Heavy-weight processes” (HWPs) have a significant amount of overhead when switching: all the tables have ...
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Scheduling

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  Scheduling:              Scheduling is a fundamental operating system function. All computer resources are scheduled before use. Since Microprocessor is one of the primary computer resources, its scheduling is central operating system design. Scheduling refers to a set of policies and mechanisms supported by operating system that controls the order in which the work to be done is completed. A scheduler is an operating system program that selects the next job to be admitted for execution. The main objective of scheduling is to increase CPU utilization and higher throughput is the amount of work accomplished in a given time interval. CPU scheduling is the basis of operating system which supports multiprogramming concepts. By having a number of programs in computer memory at the same time, the CPU may be shared among them. This mechanism improves the overall efficiency of the computer system by getting more work done in less...
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Inter-process Communication and Process Synchronization

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  Inter-process Communication and Process Synchronization:             Inter-process communication is a set of programming interfaces that allow a programmer to coordinate activities among different program processes that can run concurrently in an operating system. There are applications that involve each executing multiple processes concurrently. Processes work together to perform application-specific tasks. They are referred to as cooperating processes. Cooperating processes are “loosely” connected in the sense that they have independent private address spaces and run at different speeds. The relative speeds of the processes are not normally known. From time to time, they interact among themselves by exchanging information. An exchange of information among processes is called an interposes communication.             It is stated in that one process cannot access elem...
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Process Life Cycle

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  Process Life Cycle: The process life cycle can be divided into several stages as a state each with certain characteristics that describes each process. It means that as a process start executing it goes through one state to another state. Each process may be in one of the following stages. 1)       New 2) Ready 3) Running 4) Waiting 5) Terminate   1)       New:   The process has been created in this state. The operating system is aware of the existence of this task, but the task has not been allocated a priority and a context and has not been included into the list of schedulable tasks. 2)       Ready : There may be several tasks in ready state. The attributes of the task and the resources required to run it must be available for it to be placed in the 'ready' state. 3)       Running : This is the task which has control of the CPU. It will normally be the task...
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Scheduling (Algorithms) Policies (Priority)

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Scheduling (Algorithms) Policies (Priority): These are the following different types  of common policies or algorithms: 1)       First Come First Served (FCFS) scheduling: This is non-preemptive technique. A single queue of ready processes is maintained, and the dispatcher always picks the first one. This method does not emphasize throughput, since long processes are allowed to monopolize CPU, For the same reason, the response time with FCFS can be high (with respect to execution time), especially if there is a high variance in process execution times. This is also known FCFS scheduling. Consider the following example of two processes- In the several processes come on different job p1, p2 and p3 respectively, here p2 and p3 jobs required less than or comparatively p1 process (job), but computer run p1 process in the process of FCFS scheduler. P2 and p3 process has in ready queue in waiting process state. Advantages: These are the following advantag...
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What is an operating System

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  What is an operating System?             An operating system is an essential component of a computer system. The primary objectives of an operating system are to make computer system suitable to use and utilized computer hardware. An operating system is a program designed to run other programs on a computer. A computer’s operating system is its most important program. It is considered the backbone of a computer, managing both software and hardware resources. Operating systems are responsible for everything from the control and allocation of memory to recognizing input from external devices and transmitting output to computer displays. They also manage files on computer hard drives and control peripherals, like printers and scanners. The operating system of a large computer system has even more work to do. Such operating systems monitor different programs and users, making sure everything runs smoothly, without interference,...
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classification of operating System

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  Types of Operating System: There are many different Operating Systems. But operating systems are mainly classified in several categories. These are the following – 1)       Single user and single tasking operating system   2)       Single user and multitasking operating system 3)       Multiuser multitasking Operating System   1) Single user single tasking operating system: This operating system is very popular on personal computers. In this system one user works on a machine at a time. One program can be executed at a time. So this operating system is known as ‘Single user operating system’. If you have a large number of jobs to be executed on such a system, then you have to execute them one after another in sequence. For example: Input and output devices like the printer are very slow as compared to the speed of a CPU. When, you give the printing command a CPU reads a file ...
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