What is an operating system?

OS essential functions, including:

-displaying the GUI; managing application software; -coordinating the interaction of hardware and software; -and handling data storage and retrieval.

menus

Another common feature of most GUIs is the menu. Menus are another way you can tell your computer what to do. Menus are screens that display a list of commands. Users can tell their computers to perform a number of different actions by selecting a command from a menu. In the example below, selecting the E-mail icon opens MS Outlook.

Coordinating the interaction of hardware and software

The OS manages how application software works with other software programs as well as with the computer's hardware—the central processing unit (CPU), random access memory (RAM), mouse, keyboard, printer, etc. The OS allocates the computer's resources to enable it to perform the actions you request, such as entering information into a word processing document, printing a spreadsheet, opening your presentation, querying your database, or saving your DTP layout. This coordination is very important as there is a lot of activity going on behind the scenes when you are working on your computer.

Handling data storage and retrieval.

The OS manages the computer's filing system. It controls how information is stored on the computer and how it is accessed. Your computer has two types of files—program files and data files. Program files are the components that make your application software run. They provide the information to your word processing or spreadsheet program that tells it what to do. Typical programs may contain hundreds or even thousands of files. The image below shows you the folders and files that make up MS Office, a popular application used by many businesses.

Managing application software

The OS provides a way for you to use the programs you want. It serves as an interface, or translator between the commands you give and the computer's resources—memory, software, or printer. Application software provides instructions to your operating system. These instructions are known as "system calls" because they call on your system to provide services.

GUI

graphical user interface enabling users to easily interact with their computers

menu

list of commands

the desktop

The demonstration below shows you a computer desktop. The icons displayed on most desktops represent resources stored on the computer—files, folders, application software, and printers. Another icon commonly found on the desktop is a place to discard items.

index of all the files stored on the computer

This index is called a File Allocation Table (FAT)

window

rectangular area on a computer screen where the action takes place

The main functions the OS provides include:

-displaying the Graphical User Interface (GUI); -managing application software; -coordinating the interaction of hardware and software -handling data storage and retrieval.

Common features provided by most GUIs include:

-icons; -desktop; -menus; -windows.

windows

When you use application software, the program opens in a window. Like a window in your home, a window on your computer can open and close. A window is an opening on the computer screen where the action takes place. When you use a program, it opens in a rectangular window. The window may take up the entire screen or just a portion of the screen. The window can be resized.

icons

The GUI provides you with pictures called icons that represent different commands, or actions that you want the computer to perform, such as opening a program, or printing a document. A pointing device, such as a mouse, is used to click an icon. Clicking on the icon causes the computer to perform a task.

command

instructions that tell a computer what to do

multitasking

performing more than one task at a time

desktop

the background screen on a computer; the main work area