• Manages the computer’s resources (hardware, abstract resources, software)
• It’s a resource allocator.
• It is also used to control programs to prevent errors and improper computer use.
• It is interrupt driven.

Users and Processes access the Computer’s resources through the Operating System

OPERATING SYSTEM OBJECTIVES

Convenience: Makes the computer more convenient to use.
Efficiency: Allows computer system resources to be used in an efficient manner.
Ability to evolve: Permit effective development, testing, and introduction of new system functions without interfering with service.

SERVICES PROVIDED BY THE OPERATING SYSTEM

Operating system is responsible for managing resources. It functions same way as ordinary computer software. It is program that is executed in a way that relinquishes control of the processor. There are many services which an operating system provides:

• Context Switching & Scheduling, which allocate a process CPU time to execute its instructions.
• Memory Management, which deals with allocating memory to processes.
• Interprocess Communication, which deals with facilities to allow concurrently running processes to communicate with each other.
• File Systems, which provide higher level files out of low level unstructured data on a disk.
• High level I/O facilities, which free a process from the low-level details of interrupt handling.