what is function of operating system

what is function of operating system

An operating system performs support functions. Before the advent of operating system in the early 1960s, computer operators had to perform the support functions that are now done by the operating system. Today, operating systems successfully perform many of the functions previously assigned to operators; further more, modern operating systems perform these functions better, faster and more economically. An operating system provides an environment for the execution of programs. An Operating System has a complex mixture of diversified functions. The specific functions provided will, of course, differ from one operating system to another, but there are some common classes of functions which can be identified. Its major functions are as follows :

♦ Memory Management : Memory management involves monitoring the various storage and retrieval operations in main memory. The operating system keeps track of vital information such as which areas are and are not in use and who is using the memory at any given time. In a large system this task can be very complicated. If virtual memory is being used, for example, portions of main memory are being transferred to and from the disk, and the operating system coordinates this process. Paging and segmentation are two common methods of realizing virtual memory. Another example of complex memory management is multiprogramming, a mode of operation in which two or more computer programs are executed by a single CPU in an interleaved manner. The operating system must then coordinate the memory requirements of the several programs.

♦ CPU Management : On smaller computers, the operating system keeps track of the status of the CPU at any point. It determines, for instance, whether the control unit is in the instruction cycle or the execution cycle. When many users are competing for the CPU, the operating system must prioritize and schedule its use. Larger minicomputers and mainframes often include several CPUs, which are together referred to as a multiprocessor. In multiprocessing (operating a multiprocessor system), CPU management becomes much more complex. The major advantage of multiprocessing, from the user’s standpoint, is that a CPU will more likely be available when it is requested.

♦ Input/output and File Management : The operating system efficiently and reliably controls many different types of input and output devices, such as keyboards, printers, monitors, and audio inputs. These devices have different specifications in terms of speed, printing density, control mechanism, and other variables. The operating system is also responsible for keeping track of the files and directories that reside on hard or floppy disks.

♦ Management of Communication : The operating system manages communication among computers connected on a network. Since data exchanged on the network may be received intermittently instead of continuously, they must be combined by the operating system. The received data is then converted into a form that computers can process. The operating system also keeps track of the status of the network, disconnecting faulty portions, reporting computer usage accounts, and so on.

♦ Security : The operating system protects computers from access by illegal users and from data corruption introduced by unintentional mistakes made by legitimate users. Security is particularly important for computers that are connected to a communications network, because many users can freely access any computer. Authorized users are authenticated by entering an individual password, and then a computer usage fee is charged to the account of each user.

♦ User Interface : The operating system provides a convenient interface between a computer and its users. In the case of batch processing with mainframes, for example, users may want to run their large program only after midnight for several days until the execution of the programs is completed. In the case of personal computers and workstations, graphical user interfaces such as windows and icons displayed on a monitor are convenient, for users.

♦ Detection of Errors : The operating system constantly needs to be aware of possible errors that may occur in the CPU and memory hardware (e.g. a memory error or power failure), in I/O devices (e.g. a parity error on tape or the printer out of paper), or in the user program (e.g. an arithmetic overflow, an attempt to access illegal memory location or using too much CPU time). For each type of error, the operating system should take the appropriate action to ensure correct and consistent computing.

♦ Information Management : The operating system also monitors system information, which is organized into records and files. There are several distinct tasks of information management. These are as follows :
♦ Managing groups of file
♦ Managing file directories
♦ Processing and managing the records within a file.

Allocation of Resources : If, there are multiple users or multiple jobs running at the same time, then an operating system must coordinate the use of all available resources. A good operating system accomplishes this in the most efficient manner possible.

Besides these functions, some of the functions provided by a modern operating system is as follows :
♦ Provides for human - computer interaction
♦ Boots or starts the computer operations
♦ Schedules job
♦ Manages data and file storage
♦ Assigns different task to the CPU
♦ Provides security and control.

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