System View - The OS as a Resource Manager

• From the computer's point of view, the OS is the program most intimately involved with the hardware. In this context, we can view an OS as a resource allocator.
• Resource - ``Something valuable'' e.g. CPU time, memory space (RAM), file-storage space, I/O devices (disk), and so on.
• The OS acts as the manager of these resources. Includes multiplexing (sharing) resources in two different ways. Each program gets
  • time with the resource
  • space on the resource
• Multiple users/applications can share, why share:
  • devices are expensive,
  • there is need to share data as well as communicate
• Facing numerous and possibly conflicting requests for resources, the OS must decide
  • how to allocate them to specific programs (processes, jobs)
  • how to protect applications from one another,
  • how to provide fair and efficient access to resources,
  • how to operate and control the various I/O devices.