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Computers are not intelligent; they are tools that follow instructions prefectly and quickly.

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

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The 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.

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

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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

It stores all your programs and files.

Advantages: It can store a large amount of data ( today around 1TB). 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.

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

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.

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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...

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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 compuetr follows the instructions in the program.

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The OS defines the intrnal 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.

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.

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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.