Output Devices

The VDU (computer monitor or screen) The VDU (Visual Display Unit) is the computer screen used for outputting information in an understandable format for humans. Remember that at the end of the day the computer works in binary code (a series of on/off impulses). It is hard to realize that the original electronic computers did not have a screen!

Flat screen monitors have taken over as the VDU in 2009

Screen size You should be aware that often if you specify a screen of a certain size, say a 17-inch screen, that this is the size measured diagonally, not horizontally across the screen. If you are upgrading you should also ask for the "visible viewing area" of the screen.

What is VGA Super VGA and XGA? VGA (Video Graphics Array) was introduced way back in 1987 and was a standard that allows graphics to be displayed on your monitor. It was limited to only 256 colors and an on-screen resolution of 640 x 480 dots (or pixels).
Most people tend to use higher standards such as Super-VGA (which allows you to use more colors and a higher resolution). PCs that are more recent use even higher performance standards allowing a huge range of colors at an even higher resolution. Another terms you may hear is XGA (or XGA compatible). This gives you even higher screen resolution.

Graphics for games Many games require very advanced graphics cards (boards) to be installed within your computer to make them run. These advanced graphics cards contain their own CPU that is dedicated purely to displaying the graphics on your screen. You should find that a recent PC has this advanced graphics capability built-in where as old PCs did not.

Computer presentation projection devices These are projection devices that can be attached to your computer and are useful for displaying presentations to a group of people. They are best used in combination with presentation programs, such as Microsoft PowerPoint. They are used within education and are also very popular for sales presentations.
The price of these devices has dropped dramatically recently. When purchasing one of these devices the two things to look out for are the resolution (go for a minimum of XGA) and the brightness of the lamp (the brighter the better). Other factors to be aware of is the quietness (or otherwise of the device) and well as the cost of replacement bulbs!

Different types of printer There are many different types of printers. In large organizations, laser printers are most commonly used because they can print very fast and give a very high quality output.In most organizations, the printers are connected to the computers via a network. This means that each person with a computer does not require his or her own printer. Each computer connected to the network can print using a particular shared printer.

Laser printers Laser printers produce high print quality at high speed. They are called "laser printers" due to the fact that contain a small laser within them. There are a wide range of laser printer manufacturers and one buzzword to be aware of is Postscript, a type of printer that is designed to give very high quality reproduction of pictures.

Color laser printers Originally, most laser printers would only print in black and white (mono). More recently color laser printers have dropped in price and are entering wide spread use. While many of these produce excellent results, you should be aware of the fact that the "price per page", especially if you are using a lot of color on a page can be very high compared to the cost of printing in black and white.

Inkjet printers Inkjet printers work by using tiny jets to spray ink onto the paper. Inkjet printers are very quiet in operation and produce print quality comparable to that of laser printers, though laser printers still have the edge in terms of speed.Inkjet printers are ideal for low volume printing were high quality print is required and speed is not a high priority, e.g. printing letters in a small office or in the home.

Dot Matrix printers Dot matrix printers work by firing a row of pins through an ink ribbon onto the paper. The more pins the print head has the higher the quality of the print, most modern dot matrix printers have 24 pins.
Unfortunately, dot matrix printers can generate a lot of noise and do not produce a very high quality of print, especially when printing graphics. As a result, the dot matrix printer has now largely been replaced by the inkjet printer. Dot matrix printers are used for high volume / low quality printing, e.g. printing company pay slips.

Printer Memory It is important to realize that most printers have their own memory chips, in the same way that each computer has it’s own memory. If you are printing very large graphics (i.e. pictures), and want the best quality output from your printer then you should consider adding more memory to your printer. This must only be done by a qualified person, and has the benefit of really speeding up the rate at which you can print pages in many cases.

Plotters A plotter is an output device similar to a printer, but normally allows you to print larger images. There use is common is the design and research sector.

Speakers- Most computers are sold with the capability to add a pair of speakers to your system unit. In fact, in some cases, the monitor may have speakers built directly into the unit. This enhances the value of educational and presentation products and can now be considered a standard PC component.

Speech synthesizers - have the ability not only to display text on a monitor but also to read the text to you. Thus, you could receive a text email from a colleague and the system could read that email to you. This is of enormous benefit to the visually impaired when using a computer. On the flip side, it is now possible to use a microphone to talk to the computer and for the computer to directly convert the spoken word into text that will be displayed within say your word-processor. While these systems are far from foolproof they are getting better as more advanced software is being made available!