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Computers are not intelligent; they are tools that follow instructions perfectly and quickly. They follow instructions from the user and from the computer programmer. Applications (word processors, video games, etc.) are sets of instructions.

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Hardware is the part of the computer that we can touch. 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 card and the peripherals.

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The CPU (Central Processing Unit) is a big, green, plastic board with a lot of chips and many other electronic components mounted on it.

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.

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Memory stores information.

There are various types of memory in the computer.

Fixed memories

They normally stay inside the computer.

1. HARD DISC: Also called "hard drive", it is a set of rigid discs with a magnetic surface. It stores all your programs and files. Advantages: It can store a large amount of data (today around 1 TB). We can save and erase the information when we want. Disadvantages: It is relatively slow: compared to other types of memory, it takes longer to read and write information.

2. RAM (Random Access Memory): This is a green plastic card with chips.

The RAM is installed in a slot on the mother board.

Mother boards have empty slots so that we can add more RAM if we want.

The RAM stores the applications and files that we are using.

Advantages: It stores (writes) and retrieves (reads) quickly.

Disadvantages: We lose the work if there is an electrical power cut.

Small memory capacity (around 6GB) compared to the hard disk.

PORTABLE MEMORIES

They are easy to connect and disconnect from the computer. Also, they are easy to carry.

CDs, DVDs: We call them "optical memories" because they use light to work.

Advantages: Cheap.

Disadvantages: Not good to rewrite.

Pen drives, memory cards: They store the information in chips.

Advantages: Rewritable. Quick.

Disadvantage: More expensive than a CD or a DVD.

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The graphics card looks similar to the RAM. It is also a green plastic card with chips. 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.

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Peripherals are elements of communication between the computer and the outside world (including ourselves).

ENTRY PERIPHERALS

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

EXIT PERIPHERALS

The computer uses the exit peripherals to give information to us or to an actuator: 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 receives information from the internet and sends information to the internet.

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Software is the part of the computer that we can't touch.
It is the 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 instructions in the program.

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There is one OS per computer; not more, not less. The OS defines the internal logic for the functioning 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 computers only 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 those hardware components. In those days, the OS was stored on a floppy disk, which 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.

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Sometimes we call them "programs", but any piece of software is a program, including the operating system. 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.