What is an operating System?
Operating stystem is an integrated set of programs that controls the resources (CPU , memory, I/O devices , etc) of a computer system and provides its users with an interface or virtual machine that is easier to use than the bare machine. Accoording to this definitaion, the two primary objectives of an operating system are:
1. Make a computer system easier to use . A computer system consists of one or more processors, main memory , and many types of I/O devices such as disks, tapes, terminals, network Interfaces, etc. Writing programs for using these hardware resources correctly and efficiently is an extremely difficult job, requiring in-depth knowledge of functioning of these resources. Hence, to make computer systems usable by a large number of users, it became clear several years ago that computer systems need some mechanism to shield programmers and other users from the complexity of hardware resources. Researchers gradually evolved a solution to handle this problem by putting a layer of software on top of the bare hardware. This layer of software manges all hardware resources of the system, and presents the users with an interface or vitual machine that is easier, safer and efficient to program and use. it is called the operating system.
Hence, an operating system hides details of hardware resources from programmers and other users. It provides a high-level interface to low-level hardware resources, making it easier for programmers and other users to use a computer system.
2. Manage the resources of a computer system: An operating system manages all the resources of a computer system. This involves performing such tasks as keeping track of who is using what resources, granting resource requests, accounting for resource usage , and mediating conflicting requests from different programs and users. Efficient and fair sharing of system resources among users and/or programs is a key goal of all operating systems.
