- speed
- accuracy
- versatility
- storage capabilities
- communications capabilities
Speed
Computers operate with lightning-like speed, and processing speeds are increasing as computer manufacturers introduce new and improved models. Contemporary personal computers are capable of executing billions of program instructions in one second. Some larger computers, such as supercomputers, can execute trillions of instructions per second, a rate important for processing the huge amounts of data involved in forecasting weather, monitoring space shuttle flights, and managing other data-intensive applications.
Accuracy
People sometimes blame human errors and mistakes on a computer. In truth. computers are extremely accurate when accurate programs and data are entered and processed. A popular expression among computer professionals is garbage in, garbage out (GIGO), which means that if inaccurate programs and/or data are entered into a computer for processing, the resulting output will also be inac- curate. It is the user's responsibility to make certain that programs and data are entered correctly.
Versatility
Computers are perhaps the most versatile of all machines or devices. They can perform a variety of personal, business, and scientific applications. Families use com- puters for entertainment, communications, budgeting, online shopping, completing homework assignments, playing games, and listening to music. Banks conduct money transfers and account withdrawals via computer. Retailers use computers to process sales transactions and to check on the availability of products. Manufacturers can manage their entire production, warehousing, and selling processes with computerized systems. Schools access computers for keeping records, conducting distance-learning classes, scheduling events, and analyzing budgets. Universities, government agencies, hospi- tals, and scientific organizations conduct life-enhancing research using computers.
Storage
Storage is a defining computer characteristic and is one of the features that revo lutionized early computing, for it made computers incredibly flexible. A computer is capable of accepting and storing programs and data. Once a program is stored in the computer, users can access it again and again to process different data. For example, a user repeatedly can access a spreadsheet program such as Microsoft Excel to track budget expenditures and to project possible outcomes if income and expenses change. Computers can store huge amounts of data in comparably tiny physical spaces. For example, one compact dise can store about 109.000 pages of magazine text, and the capacities of internal storage devices are many times larger.
Communications
Most modern computers contain special equipment and programs that allow them to communicate with other computers through telephone lines, cable connec- tions, and satellites. Computers having this capability are often linked together so users can share programs, data, information, and equipment such as a printer. The structure in which computers are linked together using special programs and equipment is called a network, as shown in Figure 1-2. Newer communications technologies allow users to exchange information over wireless networks using wireless devices such as personal digital assistants (PDAs), notebook computers,cell phones, and pagers. A network can be relatively small or quite large. A local area network (LAN) is one confined to a relatively small geographical area, such as a building factory.