The phrase has been fondly referred to as WYSIWYG (pronounced “ wyziwig”) among professionals and ordinary users. The phrase, or the term “wysiwig” probably best simplifies the close association between the two most popular and most commonly used output devices: the monitor and the printer.

          While monitors provide users temporary “soft copies” of results, printers provide people with permanent and tangible “hard copies” of processing results. Printers produce hard copy results such as letters, management reports, and program listings. Printer output can come in form of words, number, and graphics very much like the monitor. Before and even during the printing process, output is usually viewed by the user on the monitor.

          Printers are classified according to the means by which images are transferred on paper. Hence, printers are of the impact and non-impact type.

          Impact printers. To transfer image on paper, impact printers use mechanical pressure very much like the typewriter. Images are transferred on paper by physically striking the ribbon against the paper by a print hammer. This mechanical action produces a controlled impact enough to transfer image from the hammer, to the ribbon, and finally to the paper.

          Impact printers rely on dot-matrix and daisy-wheel technology.
 

• Dot-matrix printers are the least expensive and most commonly used type of printer. The printer arranges dots to form characters and images. The hammers, or pins (contained in a box called printhead) are activated to form images with dots as the printhead moves horizontally across the paper.
• Daisy-wheel printers are known for their high-quality printing and are popular among professionals who use it for word processing and correspondence. The daisy-wheel printer consists of a replaceable wheel with sets of spokes. Each spoke contains a raised character very much like the typewriter. In fact, some electronic typewriters use the daisy-wheel technology.

          Non-impact printers use ink-jet or laser technology. While you may not have the opportunity to use non-impact printers in your laboratory class, it is worth getting familiar with this type of printers because they are continually getting cheaper and more popular.
 

•  Ink-Jet Printers. Ink-jet printers contain jet nozzles that spray electrically charged ink through an electric field, which deflects the ink to produce a dot-matrix character or image. Many models of ink-jet printers are capable of printing in color.
•  Laser Printers. Utilizing the technology of xenographic copy machines, laser printers are becoming popular because of it’s high quality output and it’s continually decreasing cost. Just like the copying machines you are familiar with, laser printers contain a light scan, drum, and toner that are used to transfer an image into a sheet of paper. Laser printers are capable of printing outputs with resolutions of 300 dots per inch to 600 dpi. The higher the resolution, the better the quality of printed image. Typically, today’s laser printers can print up to 8 sheets per minute and can produce documents that combine text and graphics on the same page.