Computer+OS+Architecture

=Operating systems= The functions performed by an operating system include:
 * controlling and managing the computer hardware and its resources (eg. RAM, hard disk, peripherals, network, display, etc.)
 * providing a way of selecting, launching and quitting programs
 * storing and organizing all of the programs and data
 * allowing for updates and improvements

=Operating system architecture= Computer operating systems have a software structure that is built on top of the computer hardware.

Applets/dynamic content - eg. javascript, VBscript, Silverlight, Flash. Runs within specific applications Applications - end user programs such as Word, Firefox, Media Player GUI - Graphical user interface. Provides a display and input framework for applications Kernel services - provide additional (non-core) functionality. eg. Java, sound mixer, DirectX/OpenGL Kernel - the functional core of the OS that manages the hardware HAL - Hardware Abstraction Layer. Provides a connection between the Kernel and specific types of hardware. Hardware (including BIOS) - performs power-on self-test (POST) and loads the OS.

All operating systems are different, and support different end-user applications.