Operating System Introduction
Posted By Akash Kurup on April 29, 2016
- An operating system (OS) is system software that manages computer hardware and software resources and provides common services for computer programs.
- The operating system is a component of the system software in a computer system. Application programs usually require an operating system to function.
- Time-sharing operating systems schedule tasks for efficient use of the system and may also include accounting software for cost allocation of processor time, mass storage, printing, and other resources.
- For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between programs and the computer hardware although the application code is usually executed directly by the hardware and frequently makes system calls to an OS function or is interrupted by it.
- Operating systems are found on many devices that contain a computer – from cellular phones and video game consoles to web servers and supercomputers.
- Examples of popular desktop operating systems include Apple OS X, Linux and its variants, andMicrosoft Windows.
- So-called mobile operating systems include Android and iOS. Other classes of operating systems, such as real-time (RTOS), also exist.
Objectives of Operating Systems
Modern Operating systems generally have following three major goals. Operating systems generally accomplish these goals by running processes in low privilege and providing service calls that invoke the operating system kernel in high-privilege state.
- To hide details of hardware by creating abstraction
An abstraction is software that hides lower level details and provides a set of higher-level functions. An operating system transforms the physical world of devices, instructions, memory, and time into virtual world that is the result of abstractions built by the operating system. There are several reasons for abstraction.
First, the code needed to control peripheral devices is not standardized. Operating systems provide subroutines called device drivers that perform operations on behalf of programs for example, input/output operations.
Second, the operating system introduces new functions as it abstracts the hardware. For instance, operating system introduces the file abstraction so that programs do not have to deal with disks.
Third, the operating system transforms the computer hardware into multiple virtual computers, each belonging to a different program. Each program that is running is called a process. Each process views the hardware through the lens of abstraction.
Fourth, the operating system can enforce security through abstraction.
- To allocate resources to processes (Manage resources)
An operating system controls how processes (the active agents) may access resources (passive entities).
- Provide a pleasant and effective user interface
The user interacts with the operating systems through the user interface and usually interested in the “look and feel” of the operating system. The most important components of the user interface are the command interpreter, the file system, on-line help, and application integration. The recent trend has been toward increasingly integrated graphical user interfaces that encompass the activities of multiple processes on networks of computers.