How Operating Systems Work

         Operating systems is a software that controls the many different operations of a computer.  It also directs and coordinates in processing programs.  Its remarkable complex set of instructions schedule series of tasks to be performed by the computer and allocates them to the computer's various hardware systems, such as the central processing unit, main memory, and peripheral systems. When a computer is executing several tasks simultaneously, the operating system acts to allocate the computer's time and resources in the most efficient manner, by prioritizing some jobs over others in a process called time-sharing.  An operating system also governs a computer's interactions with other computers in a network. 

Generally, there are six categories of tasks in which the operating systems perform.  These categories are as follow:

·        Processor management - The heart of managing the processor is to ensure that each process and application receives enough of the processor's time to function properly. The operating system directs the central processor in the loading, storage, and execution of programs.

·        Memory management - The management of memory involves the assurance that each process must have enough memory to execute, without running into the memory space of another processor, nor be run into by another process.  In addition, it must make sure that different types of memory in the system are used properly, so that each process can run effectively.

·        Device management - Device management controls the input and output of data to and from the peripheral devices. The operating system is responsible for providing central management of all devices, not just disk drives. When a new type of peripheral is added to the computer, the operating system is updated with a new driver for that device. The driver contains specific instructions necessary to run it. The operating system calls the drivers for input and output and the drivers talk to the hardware.

·        Storage management - The operating systems direct the central processor to store information in cache, main memory (RAM), or in any secondary memory (disk storage).  The operating systems main purposes here are to assist in finding available storage location to store data.

·        Application interface – When there is more than one particular type of computer using the operating system, or when the hardware making up the computer is ever open to changes, provision of a consistent application interface is essential.  A consistent application program interface (API) allows a software developer to write an application on one computer.  Yet, still have a high level of confidence that it will run on another computer of the same type, even if the amount of memory or the quantity of storage is different on the two machines.  The roles of the operating systems here are to allow communication among different applications in the system.

·        User interface - Just as the API provides a consistent way for applications to use the resources of the computer system, a user interface (IU) brings structure to the interaction between a user and the computer.  The main purpose is to make it easier for the user to manipulate the functions of the operating system. 

Hence, the primary goals of an operating system are to make the computer system convenient to use and to utilize the computer hardware in an efficient manner.   

Source:  This is a summary from http://www.howstuffworks.com/operating-system.htm 

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