They follow instructions from the user and from the computer programmer.

The processor is the brain of the computer; it looks at the information and takes decisions based on logic.

FIXED MEMORIES:

They normally stay inside computer.

1. HARD DISC: Also called "hard drive" , it is a set of rigid discs whit a magnetic surface.

Advantages: It can store a large amount of ddata( 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

   This is a green plastic card wuit chips.

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

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

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

Small memory capacity (around 6GB) compared to the ard 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: Nor good to rewrite.

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

Advantages: Rewritable.

Quick.

Disadventages: More expemsive than CD or DVD.

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

We need a powerful grapichs cards to play video games,to watch movies and for grapich design.

ENTRY PERIPHEALS: Entry peripheals give information to the computer: screen,speakers,pinter,light bulb,motor...

A peripheal can be both entry and exit; an example is the router to connect to the intrnet.

EXIT PERIPHEALS: The computer uses the exit peripheals to give information to us or to an actuator: screen,speakers,printer,light bulb,motor...

A peripheal can be both entry and exit; an example is the router to connect to the internet.

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, the computer follows the instructions in the program.

THE OPERATING SYSTEM ( OS )

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.

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 whit 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...

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)...

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

Application suites normally include a word procesor, a spreadsheet, a web browser and other applications.