Output devices are hardware devices that allow data to be output from a computer. CRT monitors are the least expensive type of monitor, although they are becoming increasingly rare as TFT monitors are now taking over. Printers can be divided into two distinct categories Impact printer and non-impact printer. Impact printers operate by striking the paper. Non- impact printers operate by striking a head against a ribbon. Some of the common impact printers are Drum printer, Chain printer and Dot-Matrix printer. Some of the commonly used nonimpact printers are Thermal printer, laser printer and inkjet printer. Drum printer consists of cylindrical drum. Drum is rotated at very a high speed. Character is printed by striking hammer against embossed characters on surface. Chain printer has characters engraved in type assembled on a chain. With the rotation of band, hammer is activated when desired character comes in front of it.
Inkjet printer uses a continuous stream of ink drops to print characters on paper. The print head contains tiny nozzles that spray drops of ink on the paper. Inkjet printers are used where low output volumes are required. A drum plotter is a plotter that uses a drum or roller to move the paper during printing while the actual pen performs the printing. A flatbed plotter plots on a paper that is fixed over a rectangular flatbed table. It uses two arms for drawing.