Operating Systems

An operating system (OS) is an essential piece of software that is loaded when a computer boots up.

Purpose

The purpose of an OS is a piece of system software which controls the hardware within a computer.

API

Operating systems provide an application programming interface (API). This is a set of code libraries that software developers can use to write applications for that operating system.

Managers

The operating system is responsible for many pieces of hardware, each of which is controlled by a dedicated 'manager':

• The user interface (UI) manager provides the user interface which allows users to control the computer.
• The device manager allocates resources to external hardware devices and allows them to be used by applications.
• The memory manager controls the allocation of memory between applications.
• The user manager authenticates and separates users of the computer.
• The process manager controls the allocation of central processing unit (CPU) cycles to multiple running applications.
• The file manager controls the opening, reading and writing of files in secondary storage.