^{They follow instructions from the user and from the computer programmer.}

^{Applications (word processors, video games, etc.) are sets of instructions.}

^{The hardware is the components that are interconnected. The computer needs all those components, but they are independent and we can change any of them.}

^{The basic components are the CPU, the memory, the graphics and the peripherals.}

^{The central processing unit is also called "the processor". It is the "brain" of the computer; it looks at the information and takes decisions based on logic.}

^{There are various types of memory in the computer:}

1. ^{Hard disc}

2. ^RAM

3. ^CD

4. ^DVD

5. ^{Pen drives}

6. ^{Memory cards}

^{It defines the format of the graphics and helps the processor to process the graphics faster.}

^{We need a powerful graphics cards to play video games, to watch movies and for graphic design.}

Entry peripherals:

^{Entry peripherals give information to the computer: keyboard, mouse, microphone, thermostat...}

Exit peripherals:

^{The computer uses the exit peripherals to five information to us or to an actuater: screen, speakers, printer, light bulb, motor...}

^{A peripheral can be both entry and exit; an example is the router to connect to the internet.}

^{The router recives information from the internet and sends information to the internet.}

^{It is teh logic that the computer follows.}

^{The Programmer writes instructions. A set of instructions is a "program". When we use a program, the computer follows the instruction in the program.}

^{The OS defines the internal logic for the funtioning of the computer.}

^{To program the OS, we must know which are the components of the hardware and how they are connected.}

^{For example, when we tell the computer to switch off, the OS decides to first close the applications, then to transfer all data from the RAM to the HD, and finally to switch itself off.}

^{Operating systems evolve along with computers. In the 1980s only one user could interact with a computer and cmputers anly had text, not images.}

^{Computers had one processor, one application, one floppy disc, one keyboard and one screen.}

^{The OS was programmed only to manage these hardware components.}

^{In those days, the OS was stored on a floppy disk, wich was loaded after switching on the computer.}

^{The user first loaded the OS, (stored on an external disk) and then the application (stored on another external disk). the user could then start to use the application.}

Today's OS

^{It is stored in the hard disc (the applications are also stored in the HD).}

^{It can manage multiple applications at the same time. It has a graphic display, so we can interact with the computer using a mouse.}

^{It can connect to the internet.}

^{Today, the most common operating systems are those sold by Microsoft: Windows Vista, Windows 7... Microsoft's Windows has a long history which started with the OS called "DOS" (Disc Operating System). Apple Macintosh is another company which offers an OS for computers. The "Mac" is preferred by graphic designers and artists.}

^{LINUX is a free OS. "Free" means that users don't have to pay to use it, and that programmers can modify the OS as they like.}

^{There are also various OS for mobile telephones.}

^{Applications are programs that we use to do things on the computer; they are our tools. You probably know a lot of them already: Word (word processor), Excel (spreadsheet), Access (database), PowerPoint (presentations), FIFA 11 (game), Messenger (telecommunication software), Autocad (CAD)...}

^{An "application suite" is a group of applications in a package. For example: Open Office, Microsoft Office or iWork'09.}

^{Application suites normally include a word processor, a spreadsheet, a web browser and other applications.}

^{The applications in the suite have a common user interface so that the user can easily learn how to use all of them.}

^{The different applications of an application suite can interact with each other. So we can, for example, insert a spreadsheet in a word processor document.}