Operating System

The Operating system (OS) controls the computer, and without it you could not make use of the computer. The OS is software that runs between the hardware and application software. It enables application software to use the computer’s hardware and other resources.
  * 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... [continues]

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