Goals of OS

It is easier to define an operating system by what it does than what it is, but even this can be tricky. The primary goal of some operating system is convenience for the user. The primary goal of other operating system is efficient operation of the computer system. Operating systems and computer architecture have influenced each other a great deal. To facilitate the use of the hardware, researchers developed operating systems. Users of the operating systems then proposed changes in hardware design to simplify them. In this short historical review, notice how identification of operating-system problems led to the introduction of new hardware features.

• 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.