some of the devices available, it is worth making some observations:
n The output produced by some devices is temporary in nature. A display shown on a monitor, for example, is lost when a new image is shown or the computer system is switched off. On the other hand, a report produced on a printer is more permanent and may last for many years.
n Some forms of output may be used as the input for another process. Photographs, sounds and video sequences, for example, might be combined during the production of a training package or demonstration programme.
n Business organisations have a wide range of requirements in terms of the form of the information they produce. These requirements mean that there are a large variety of specialised output devices available.
OUTPUT DEVICES
Display devices
The most common output device is almost certainly the monitor that is attached to all personal computer systems.
Most modern monitors feature a Liquid Crystal Display (LCD), making them more reliable and energy efficient than their predecessors. Better energy efficiency can be obtained if LEDs (Light Emitting Diodes) are used to provide the backlight needed to illuminate the display. The latest OLED (Organic Light Emitting Diode) technology does not need a backlight, allowing for better quality images and thinner screens. While all modern monitors are essentially liquid crystal displays, they may sometimes be known as LED or OLED monitors, depending on the technology being used.
The monitor has several advantages over other forms of output device:
n Information can be shown instantly with only a negligible delay between the information becoming available and its being displayed. In addition, the monitor is one of only a small number of devices that allows users to view the progress of an activity as it occurs.
n As standard components of a computer system, monitors are relatively inexpensive to purchase, repair or replace.
n The monitor is particularly suited to displaying certain kinds of information, for example charts and graphics.
n The cost of using the monitor as an output device is very low. Unlike printers, for example, a monitor does not require consumables, such as paper. In turn, this means that wastage does not occur.
Another way of producing a large display for presentations is by making use of a data or video projector. A computer system can be connected directly to a projector so that output is directed to a projection screen.
Video projector A computer system can be connected directly to a projector so that output is directed to a projection screen.
Printers and plotters
Since many users are involved in selecting printers these are described in a separate section.
A plotter uses a number of different coloured pens to draw lines upon the paper as it moves through the machine. Although capable of producing characters, the quality of the text
Plotter
A plotter uses a number of different coloured pens to draw lines upon the paper as it moves through the machine.
Figure 3.4 Output devices in context
Info
Input Processing Output
Storage PC hardware system Data
n A computer-based information system will seldom make use of only a single output device. Even a typical personal computer will often feature several different output devices, such as monitor, sound card and printer.
created is often very poor. Plotters are primarily used to create technical drawings, such as engineering diagrams and to record the progress of continuous monitoring. In recent years, the use of plotters has declined as large inkjet printers have become more accessible.
Other output devices
In addition to the items described in this section, a wide variety of other output devices are also available. Some examples include the following:
n Sound. In addition to music and sound output via speakers, a sound card can be used to output information in a variety of other forms. Two common examples are voice annotations and speech synthesis.
n MIDI devices. The ability to link devices to a personal computer via MIDI (musical instrument digital interface) connections allows users to send information directly to one or more musical instruments.
n Microfilm. Computer output to microfilm (COM), also known as ‘computer output microform’, is often used to archive large quantities of information for future reference.
Information is processed via a personal computer and sent directly to a device that produces microfilm negatives. COM has largely been replaced by more modern document image processing systems, which tend to be less expensive to operate and offer more flexibility in terms of how information can be used.
MIDI (musical instru-ment digital interface) MIDI connections allow users to control musical instruments or synthesise any sounds or effects required in order to play the music.
Computer Output to microfilm (COM) Information is processed via a computer and sent directly to a device that produces microfilm negatives.
Selecting output devices
The selection of an inappropriate output device can incur unnecessary costs and lead to a variety of other problems. Some of the factors that should be considered when selecting an output device include appropriateness, permanence, speed, response time and cost.
Appropriateness
An output device should be appropriate to the type of information produced as the result of a business process. A plotter, for example, provides an efficient means of producing large technical diagrams, but would not be an appropriate way of printing a business letter.
Permanence
It is often necessary to make a permanent record of the results of a given activity, for example an organisation will normally retain a copy of a business letter sent to a client.
Response time
Many activities require constant and immediate feedback. The user of a word processor, for example, needs to see the results of their actions at all times – in other words, the response time between action and feedback must be very small.
Speed
In many applications, the speed of the output device can be of critical importance. As an example, consider a mailmerge operation, where personalised letters are produced by inserting the names and addresses of customers into a standard document. Although generating each letter may take only a matter of seconds, printing each copy can take considerably longer. The time taken to complete the process will depend heavily on the speed of the output device: the slower the device (in this case, the printer), the longer the overall time taken to complete the task.
Response time The time it takes to respond to an action.
For instance, the delay between pressing a key on the keyboard, and a letter appearing on the screen. The same term can also refer to the time it takes for a maintenance provider to fix a problem.
Cost
The operating costs of certain output devices can be extremely low. The monitor, for example, costs relatively little to purchase, maintain and operate. However, other output devices, for example printers, incur costs each time they are used.
Using the criteria described in this section and using numerical specifications, select the most suitable type of screen output device and configuration to perform these functions:
n a business analyst involved in using a spreadsheet to model a company’s financial performance;
n a student using a PC to produce assignments;
n a web site designer;
n a personal assistant to the director.