XEROGRAPHIC PRINTERS.\ Xerographic printers use a printing technique very similar to the methods used in duplicating or copying machines. The printers can operate at speeds up to 4,000 lines per minute.

ELECTROSTATIC PRINTERS.\ Electrostatic printers use a special photographic paper that allows characters to be etched onto the paper using a stylus. The stylus, made up of tiny wires, forms characters by placing an electrostatic charged image on the paper. Then, as the paper is moved through a toner solution containing ink particles, the ink adheres to the charges that form a pattern on the paper to develop the character. This type of printer can be used for both printing and plotting (displaying graphic output), and can print up to 5,000 lines per minute.

INK JET PRINTERS.\ Ink jet printers employ a technique very similar to the way we use a can of spray paint and a stencil. A spray of electrically charged ink is shot (under pressure) toward the paper. Before reaching the paper, the ink is passed through an electrical field, which forms the letters in a matrix form. The print resulting from this process consists of easy to read, high-quality characters. Some manufacturers use large droplets of ink for faster printing, while others use small droplets for better clarity but with slightly reduced printing speeds. This type of printer can print up to 300 characters per second.

LASER PRINTERS.\ Laser printers direct a beam of light through a rotating disk containing the full range of print characters. The appropriate character image is directed onto photographic paper, which is then put through a toner, developed, and used to make additional copies. The print resulting from this process consists of sharp, clean images that are easy on the eyes. These printers can print up to 20,000 plus lines per minute.

Many micro printers can print subscripts and superscripts, print in several different colors, print graphic material, and output text in several different type styles (fonts).

Some printers print in a single direction only, like the conventional typewriter, whereas others print in both directions (bidirectional) to save on time-consuming carriage returns. Many come with either a friction feed (for handling single-sheet paper) or an adjustable tractor feed (for handling continuous forms), and some even have both.

You can initiate a wide range of printer functions either through the applications program you are working with or by using the controls located on the front of the printer's operating panel. These controls can be buttons, lights, and switches. With a simple touch of a button, you can change such things as type style, letter quality, pitch, and spacing. It's that simple.

As mentioned, most printers are equipped with an operating control panel that allows you to change various settings. For example, you can change the number of characters per line or lines per inch, change fonts and type size, and switch from draft to letter-_{quality mode.} You can choose any combination of

Figure 1-23.\Dot matrix printer showing operating control panel.

features quickly and easily. The printer we are using as our example is a dot matrix printer (shown in figure 1-23). Dot matrix printers are widely used with microcomputers in the workspaces. You will become very familiar with their operation.

PRINTER OPERATING CONTROL PANEL.\ The operating control panel shown in figure 1-24 displays the buttons that control various functions along with several indicator and warning lights that show you what functions are currently in operation. Listed below are some of the more common CONTROL BUTTONS and INDICATOR/WARNING LIGHTS you are likely to see and use on this type of printer.

_{Control Buttons. \}You can set up various functions and control printing functions by manually pushing control buttons. To activate the buttons, you must first put the printer in an offline status. Normally, this is done by depressing the online button.