The input and output devices or input / output units are the physical equipment connected to the computer. These devices allow information to be communicated between the user and the computer or to handle an information medium.
They are also called computer peripherals or input and output peripherals because they are separate from the central processing unit.
Input / output devices are classified by the functions they can perform on input devices, output devices, and input and output devices.
The input devices are those equipment in charge of entering data into the central memory of the computer for processing. Through them the input information is transformed into electrical signals.
Examples of input devices we can mention the following:
1. Keyboard : allows communication between the user and the computer. It has a set of keys grouped into four blocks called alphabetic, numeric, control and function keys.
2. Mouse or computer mouse : it is an input unit made up of a small box with controls that adapts to the hand and allows the movement of the cursor on the screen. There are mechanical, optical and opto-mechanical mice.
3. Bar code reader : an optical pen or a light beam formed by a laser beam is used capable of making a three-dimensional image that allows the code to be read in any position.
4. Optical disc drive : they are units for reading and writing optical discs. They use a recording and reading technique where reflections of certain wavelengths on a surface are analyzed by means of a light beam produced by a laser beam.
5. Scanner or scanner : data entry device used to digitize documents in physical format, such as photographs and texts, to be processed on the computer.
6. Control lever for games or joystick : it consists of a box from which a lever or mobile control comes out that sends the information on the movement of the lever and is registered as positions on the screen. They are used in video games and graphic applications.
7. Microphone : these are devices that receive audio signals and transform them into electrical signals that are processed by the computer.
8. Digital still camera : a device that can be used to insert images without the need for development.
9. Digital video camera or WebCam : it is a camera that transmits images in real time to a computer.
10. Graphic tablet or digitizer table : allows the user to draw or write by hand with a special pen, the image of which appears on the computer screen.
11. Analog data acquisition systems : these are devices with sensors that detect physical variables, such as temperature and pressure, and transform those analog signals to digital for processing by a computer.
Output devices are computers that present information to the user in an understandable way, either through images, text, sounds or touch. These perform the function of extracting data from the central memory to the outside.
As examples of output devices we find:
1. Screen or display : consists of a representation system by means of configurations of luminous points called pixels. Screen resolution is the number of pixels it has. On the desktop or desktop it is known as monitor.
2. Printers : they are data output units supported on paper. There are several types of printers, including thermal, electrostatic, ink, and laser printers.
3. Loudspeaker : these are devices that transform electrical signals into audio signals.
4. Graphic plotters or plotters : they are devices capable of printing a graph or drawing.
5. Robots : they are output units that have a mechanical complement capable of performing ordered movements from the computer.
6. Speech generators : are devices capable of giving an audible output through a speech synthesizer.
The input and output devices or mixed devices allow the introduction and extraction of data in the central memory.
Examples of mixed devices are:
1. Touch screen : it is a screen that includes a device that recognizes the area of the screen where a small contact with the finger has been made.
2. Multifunction printers : these are computers with the ability to perform various functions, such as printing, scanning and copying.
3. MIDI keyboard ( Musical Instrument Digital Interface ) : these are musical keyboards similar to electronic pianos that allow the interconnection of different musical instruments and electronic accessories. They can receive both the signals of musical instruments and generate sounds.
4. Point of sale terminals : these are special input / output units for commercial applications. These devices have replaced the old cash registers.
5. Terminals for financial operations : better known as automated teller machines, they are units connected to a central computer of a financial institution to carry out operations for the customers of said entity.