OPERATING SYSTEM OVERVIEW
Objectives and Functions
A program that is executed by the processor that frequently relinquishes control and must depend on the processor to regain control.
· A program that mediates between application programs and the hardware
· A set of procedures that enable a group of people to use a computer system.
· A program that controls the execution of application programs
· An interface between applications and hardware
v Users of a computer system:
v Programs - use memory, use CPU time, use I/O devices
v Human users
v Programmers - use program development tools such as debuggers, editors end users - use application programs, e.g. Internet explorer
hardware + software
OS is a part of the computer software, it is a program. It is a very special program, that is the first to be executed when the computer is switched on, and is supposed to control and support the execution of other programs and the overall usage of the computer system.
The operating system controls the usage of the computer resources - hardware devices and software utilities. We can think of an operating system as a Resource Manager. Here are some of the resources managed by the OS:
· Main memory,
· Secondary Memory,
· Peripheral devices,
The operating system provides a number of services to assist the users of the computer system:
For the programmers:
Utilities - debuggers, editors, file management, etc.
For the end users - provides the interface to the application programs
For programs - loads instructions and data into memory, prepares I/O devises for usage, handles interrupts and error conditions.