Monitors

Printers

Dot-matrix printers use a set of pins on a print head to create an image on a page. The print head moves back and forth across the page while the pins strike the paper in different combinations, through an inked ribbon. The quality of the image improves with a greater number of pins. Earlier dot-matrix printers had nine pins resulting in a vertical resolution of only nine dots. Newer models have 24 pins resulting in a greater overlap of dots and less white space, or higher resolution.

Laser printers use a separate small computer, as well as a laser and toner, to produce an image. The printer's computer interprets the data from the microcomputer, and controls the laser. The laser charges a drum which then picks up particles of ink having an opposite electronic charge, called toner. The toner is transferred from the drum to paper using heat and pressure, much like a photocopier. Unlike dot-matrix printers, laser printers are quiet and produce higher quality output. Resolution on a laser printer is measured in dots per inch or DPI. An average printer can have 300 DPI while a high-end laser printer can have 1800 DPI.

Ink-jet printers spray ink from a set of small nozzles directly onto paper. Up to 64 nozzles are located on the print head which sweeps across the page line by line, much like a dot-matrix printer. The resolution of an ink-jet printer is higher than a dot-matrix printer, but its output is not as clear as that of a laser printer. Ink-jet printers are capable of bright, colour output.

Other high-end printers:

• Thermal Wax Colour Printers use special ribbons to produce images on glossy paper. This makes them good for transparencies.
• Phase-change Colour Printers use coloured wax sticks to produce plain-paper prints.
• Dye-sublimation Colour Printers use special ribbons and paper to produce photo-quality prints.

Plotters

Image Setters

Sound Systems