ICT Second Opportunity

1. Computer System

1.1 Hardware

Hardware is defined as a join of components of physical devices that intervene in a computer system.

It is also noun as the mechanical equipment necessary for conducting an activity, usually distinguished from the theory and design that make the activity possible.

http://dictionary.reference.com/browse/hardware

The components of a computer can be classified, according to the function they perform in: Input devices, Output devices, Processing and Storage.

1.1.1 Input Devices

They are the ones from which the information is introduced to the computer to be processed or transformed. Some examples are: keyboard, bar code reader, scanner, mouse, webcam, microphone, touch screen, etc.

Many input devices can be classified according to:

• Modality of input (e.g. mechanical motion, audio, visual, etc.)

• The input is discrete (e.g. key presses) or continuous (e.g. a mouse's position, though digitized into a discrete quantity, is fast enough to be considered continuous)

• The number of degrees of freedom involved (e.g. two-dimensional traditional mice, or three-dimensional navigators designed for CAD applications)

Pointing devices, which are input devices used to specify a position in space, can further be classified according to:

• Whether the input is direct or indirect. With direct input, the input space coincides with the display space, i.e. pointing is done in the space where visual feedback or the pointer appears. Touchscreens and light pens involve direct input. Examples involving indirect input include the mouse and trackball.

• Whether the positional information is absolute (e.g. on a touch screen) or relative (e.g. with a mouse that can be lifted and repositioned)

http://en.wikipedia.org/wiki/Input_device

1.1.2 Output Devices

They are the ones that show the user the data previously transformed or processed. The most used are: the printer, which shows the information in written form, the monitor, which presents the information in a visual form, the speakers, which present the information in sound form.

Display device

A display device is an output device that visually conveys text, graphics, and video information. Information shown on a display device is called soft copy because the information exists electronically and is displayed for a temporary period of time. Display devices include CRT monitors, LCD monitors and displays, gas plasma monitors, and televisions.

http://en.wikipedia.org/wiki/Output_device#Display_devices

1.1.3 Storage Devices

They are the ones that permit to store or to save information. These are classified in: main and secondary memory.

 The main memory

This memory acts directly with the CPU in all the input and output operations, allowing to store and to recover instantly data and programs with which it is working. It’s composed by:

• ROM (read-only memory): computer memory on which data has been prerecorded. Once data has been written onto a ROM chip, it cannot be removed and can only be read.

• RAM (random access memory): a type of computer memory that can be accessed randomly; that is, any byte of memory can be accessed without touching the preceding bytes. RAM is the most common type of memory found in computers and other devices, such as printers.

http://www.webopedia.com

 The second memory

It permits to save programs and data in a permanent way; the most used storage devices are the hard disk (internal and external), the floppy disks (already becoming obsolete), compact disks (CD), digital video disks (DVD), memories USB, among others.

1.2 Processing devices

When a computer receives data from an input device, the information must go

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