is usually part of a personal computer or part of a terminal that is connected to a computer somewhere else.

is an input device with a ball on its underside that is rolled on a flat surface, usually the desk on which the computer sits. The rolling movement causes a corresponding movement on the screen. Moving the mouse allows you to reposition the pointer, or cursor, an indicator on the screen that shows where the next interaction with the computer can take place

use optical recognition systems that have a light beam to scan input data to convert it into electrical signals, which are sent to the computer for processing. Optical recognition is by far the most common type of source input, appearing in a variety of ways: optical marks, optical characters, bar codes, handwritten characters, and images.

Each product on the store shelf has its own unique number, which is part of the Universal Product Code (UPC). This code number is represented on the product label by a pattern of vertical marks, or bars, called bar codes. (UPC, by the way, is an agreed-upon standard within the supermarket industry; other kinds of bar codes exist.

Machines that can read handwritten characters are yet another means of reducing the number of intermediate steps between capturing data and processing it. In many instances it is preferable to write the data and immediately have it usable for processing rather than having data entry operators key it in later. However, not just any kind of handwritten scrawl will do; the rules as to the size, completeness, and legibility of the handwriting are fairly rigid.

Abbreviated MICR, - is a method of machine-reading characters made of magnetized particles. The most common example of magnetic characters is the array of numbers across the bottom of your personal check.

a scanner converts a drawing, a picture, or any document into computer-recognizable form by shining a light on the image and sensing the intensity of the reflection at each point of the image. Scanners come in both handheld and desktop models. The electronic version of the image can then be stored, probably on disk, and reproduced on screen when needed. Businesses find imaging particularly useful for documents, since they can view an exact replica of the original document at any time

Another source of direct data entry is a data collection device, which may be located in a warehouse or factory or wherever the activity that is generating the data is located. As we noted earlier in the chapter, for example, factory employees can use a plastic card to punch job data directly into a computerized time clock. This process eliminates intermediate steps and ensures that the data will be more accurate

Does your computer have ears? Speaking to a computer, known as voice input or speech recognition, is another form of source input. Speech recognition devices accept the spoken word through a microphone and convert it into binary code (0s and 1s) that can be understood by the computer. Originally, typical users were those with "busy hands," or hands too dirty for the keyboard, or with no access to a keyboard

One way of getting input directly from the source is to have a human simply point to a selection. The edges of the monitor of a touch screen emit horizontal and vertical beams of light that crisscross the screen.

delivering input to a computer by simply looking at the computer would seem to be the ultimate in capturing data at the source. The principles are reminiscent of making a screen selection by touching the screen with the finger. Electrodes attached to the skin around the eyes respond to movement of the eye muscles, which produce tiny electric signals when they contract. The signals are read by the computer system, which determines the location on the screen where the user is looking.

A computer system often is designed to produce several kinds of output. An example is a travel agency that uses a computer system. If a customer asks about airline connections to Toronto, Calgary, and Vancouver, say, the travel agent will probably make a few queries to the system to receive on-screen output indicating availability on the various flights. After the reservations have been confirmed, the agent can ask for printed output that includes the tickets, the traveler's itinerary, and the invoice. The agency may also keep the customer records on microfilm. In addition, agency management may periodically receive printed reports and charts, such as monthly summaries of sales figures or pie charts of regional costs. We begin with the most common form of output, computer screens

A user's first interaction with a computer screen may be the screen response to the user's input. When data is entered, it appears on the screen. Furthermore, the computer response to that data-the output-also appears on the screen. Computer screens come in many varieties, but the most common kind is the cathode ray tube (CRT). Most CRT screens use a technology called raster-scan technology. The backing of the screen display has a phosphorous coating, which will glow whenever it is hit by a beam of electrons.

Cathode ray tube monitors that display text and graphics are in common use today. Although most CRTs are color, some screens are monochrome, meaning only one color, usually green, appears on a dark background. Another type of screen technology is the liquid crystal display (LCD), a flat display often seen on watches and calculators. LCD screens are used on laptop computers. Some LCDs are monochrome, but color screens are popular. Some laptop screens are nearing CRTs in resolution quality.

A screen may be the monitor of a self-contained personal computer, or it may be part of a terminal that is one of many terminals attached to a large computer. A terminal consists of an input device, an output device, and a communications link to the main computer. Most commonly, a terminal has a keyboard for an input device and a screen for an output device, although there are many variations on this theme.

printer is a device that produces printed paper output, known in the computer industry as hard copy because it is tangible and permanent (unlike soft copy, which is displayed on a screen). Some printers produce only letters and numbers, whereas others can also produce graphics.

use some sort of physical contact with the paper to produce an image, physically striking paper, ribbon, and print hammer together. The impact may be produced by a print hammer character, like that of a typewriter key striking a ribbon against the paper, or by a print hammer hitting paper and ribbon against a character. A dot-matrix printer is one example of an impact printer. High- quality impact printers print only one character at a time.

places an image on a page without physically touching the page. The major technologies competing in the non-impact market are laser and ink-jet. Laser printers use a light beam to help transfer images to paper, producing extremely high-quality results. Laser printers print a page at a time at impressive speeds.

We have already examined voice input in some detail. As you will see in this section, however, computers are frequently like people in the sense that they find it easier to talk than to listen. Speech synthesis is the process of enabling machines to talk to people is much easier than speech recognition. 

Personal computer users have occasionally sent primitive musical messages, feeble tones that wheezed from the tiny internal speaker. Many users remain at this level, but a significant change is in progress.

Let us take a moment to glimpse everyone's favorite, _______. Just about everyone has seen TV commercials or movies that use computer-produced animated graphics. _______ can also be found in education, computer art, science, sports, and more. But perhaps their most prevalent use today is in business.

- It might seem wasteful to use color graphics to display what could more inexpensively be shown to managers as numbers in standard computer printouts. However, colorful graphics, maps, and charts can help managers compare data more easily, spot trends, and make decisions more quickly. Also, the use of color helps people get the picture-literally.

can be as creative as an animated cartoon. Although they operate on the same principle as a moving picture or cartoon-one frame at a time in quick succession video graphics are produced by computers. Video graphics have made their biggest splash on television, but many people do not realize they are watching a computer at work. 

For more than a decade, computer graphics have also been part and parcel of a field known by the abbreviation CAD/CAM-short for __________ manufacturing. In this area computers are used to create two- and three-dimensional pictures of everything from hand tools to tractors.

There are many ways to produce and interact with screen graphics. We have already described the mouse; the following are some other common devices that allow the user to interact with screen graphics. A digitizing tablet lets you create your own images. This device has a special stylus that you can use to draw or trace images, which are then converted to digital data that can be processed by the computer.

Just as there are many different ways to input graphics to the computer, there are many different ways to output graphics. Graphics are most commonly output on a screen or printed paper, as previously discussed. Another popular graphics output device is the plotter, which can draw hard-copy graphics output in the form of maps, bar charts, engineering drawings, and even two- or three-dimensional illustrations. Plotters often come with a set of four pens in four different colors. Most plotters also offer shading features.

Another popular graphics output device is the ___, which can draw hard-copy graphics output in the form of maps, bar charts, engineering drawings, and even two- or three-dimensional illustrations. It is often come with a set of four pens in four different colors. Mostly also offer shading features.