Various devices that are attached to the computer system, augmenting the basic services provided by it, are called peripheral devices. These can be either input and output devices or various auxiliary storage units of a computer system.
Any device that outputs information from a computer is called, an output device.
Output devices enable the users to perceive the results of computer processing.
The on-screen display enables the user to view the results of data processing.
The monitors has its own processing circuitry and memory, called Video RAM (VRAM).
The screen output is referred to as a soft copy, while the printed version of the same information is called the hard copy.
Monitors use Cathode Ray Tube (CRT) technology used in television sets.
The image is formed by electrons “guns” which shoots a stream of electrons at the screen’s phosphorescent surface.
In a color monitor, three electron guns, (red, green, and blue) are used.
They fire electrons in varying intensities to produce on-screen shots.
A printer is a device that prints output to a page.
Printers are commonly categorized by the way they create print characters
Printers come in color or simply black and white .
. Most businesses have laser printers since the quality is better.
Printers can be connected to the computer or networked using a print server.
Two basic print technologies are:-
∙ Impact printers
∙ Non-impact printers
These printers can produce a page, a line, or a character at a time.
It is used for printing backup copies of large amounts of stored data.
Its print quality is poor.
Most widely used printers for personal computers.
Can produce both text and graphics with good print quality.
Most popular non-impact printers are laser printers and inkjet printers.
They are also called bubble jet printers.
They are the least expensive and most popular non-impact printers.
It work by forming an image that is composed of tiny dots, but the dots are much smaller.
They also print in color.
They are inexpensive and produce excellent output but they are slow.
These work like photocopy machines.
A laser beam creates electrical charges on a rotating print drum.
These charges attract tones, which are transferred to the paper and fused to its surface by a heating process.
Plotters are used for printing quality graphics and drawings.
There are 3 types of plotters namely flatbed plotters, drum plotters and inkjet plotters.
The flatbed plotters print graphical images by moving the pen and produce accurate pictures.
The drum plotters print graphical images moving both the drum and the pen.
In inkjet plotters, pens are replaced with inkjets.
Speakers are attached to computers for the output of sound.
Sound cards are required in the computer for speakers. Speakers come in simple two-speaker output devices.
They can also be surround sound and be expensive.
Surround-sound speakers come with two front speakers, a subwoofer and two small speakers that sit behind the computer user.
Surround-sound speakers are great for gamers.
A DVD or CD-ROM is a media device on which the user can write data and information.
DVDs have replaced CD-ROMs since they hold more information than legacy discs.
DVDs are normally used as storage backups to save documents and applications in case of a hard drive failure.
They are also used to create installation discs for software development.
Headsets are a combination of speakers and microphone.
A headset is used mostly for gamers, but it is a great tool for communicating with family or friends over the Internet using software.
Headsets retrieve sound just like speakers, but the attached microphone, which is an input device, can be used for recording sound.