Operating System (OS) It is an interface between a computer user and computer hardware. It enables applications/softwares to interact with a computer’s hardware. Its purpose is to manage a system’s hardware and software resources. It is a software which performs all the basic tasks like file management, memory management, process management, handling input and output, and controlling peripheral devices such as disk drives and printers. Now a days, Operating systems is found almost in every device like mobile phones, personal computers, mainframe computers, automobiles, TV, Toys etc. Some popular Operating Systems are: Linux Operating System, Windows Operating System, Unix, MSDOS , BOSS etc.
Kernel: The software that contains the core components of the operating system is called the kernel.
Objectives of Operating System: The objectives of the operating system are −
- To make the computer system convenient to use in an efficient manner.
- To hide the details of the hardware resources from the users.
- To provide users a convenient interface to use the computer system.
- To act as an intermediary between the hardware and its users, making it easier for the users to access and use other resources.
- To manage the resources of a computer system.
- To keep track of who is using which resource, granting resource requests, and mediating conflicting requests from different programs and users.
- To provide efficient and fair sharing of resources among users and programs.
Functions of an operating System:
- Memory Management: Memory management refers to management of Primary Memory or Main Memory. Main memory is a large array of words or bytes where each word or byte has its own address. Main memory provides a fast storage that can be accessed directly by the CPU. For a program to be executed, it must in the main memory. An Operating System does the following activities for memory management
- Keeps tracks of primary memory, i.e., what part of it are in use by whom, what part are not in use.
- In multiprogramming, the OS decides which process will get memory, when and how much.
- Allocates the memory when a process requests it to do so.
- De-allocates the memory when a process no longer needs it or has been terminated.
- Processor Management: In multiprogramming environment, the OS decides which process gets the processor when and for how much time. This function is called process scheduling. An Operating System does the following activities for processor management −
- Keeps tracks of processor and status of process. The program responsible for this task is known as traffic controller.
- In multiprogramming, the OS decides which process will get processor, when and for how long.
- Allocates the processor (CPU) to a process.
- De-allocates the processor when a process no longer needs it or has been terminated.
- Device Management: An Operating System manages device communication via their respective drivers. It does the following activities for device management −
- Keeps tracks of all devices. Program responsible for this task is known as the I/O controller.
- Decides which process gets the device, when and for how much time.
- Allocates the device in the efficient way.
- De-allocates the device when a process no longer needs it or has been terminated.
- File Management: A file system is normally organized into directories for easy navigation and usage. These directories may contain files and other directions. An Operating System does the following activities for file management −
- Keeps track of information, location, uses, status etc. The collective facilities are often known as file system.
- Decides who gets the resources/files.
- Allocates the resources/files to decided processes.
- De-allocates the resources/files when a process no longer needs it or has been terminated.
- Other Important Activities: Following are some of the important activities that an Operating System performs −
- Security − By means of password and similar other techniques, it prevents unauthorized access to programs and data.
- Control over system performance − Recording delays between request for a service and response from the system.
- Job accounting − Keeping track of time and resources used by various jobs and users.
- Error detecting aids − Production of dumps, traces, error messages, and other debugging and error detecting aids.
- Coordination between other softwares and users − Coordination and assignment of compilers, interpreters, assemblers and other software to the various users of the computer systems.