Computers are used extensively in scientific research to solve mathematical problems, display complicated data, or model systems that are too costly or impractical to build, such as testing the air flow around the next generation of space shuttles. The military employs computers in sophisticated communications to encode and unscramble messages, and to keep track of personnel and supplies.
IIIHOW COMPUTERS WORKThe physical computer and its components are known as hardware. Computer hardware includes the memory that stores data and instructions. The programs that run the computer are called software. Software generally is designed to perform a particular type of task.
AThe Operating SystemWhen a computer is turned on it searches for instructions in its memory. Usually, the first set of these instructions is a special program called the operating system, which is the software that makes the computer work. Popular operating systems, such as Microsoft Windows and the Macintosh system have a graphical user interface -that is, a display that uses tiny pictures, or icons, to represent various commands. To execute these commands, the user clicks the mouse on the icon or presses a combination of keys on the keyboard.
BRange of Computer AbilityComputers exist in a wide range of sizes and power. The smallest are embedded within the circuitry of appliances, such as televisions and wrist watches. These computers are typically preprogrammed for a specific task, such as tuning to a particular television frequency or keeping accurate time.
The smallest of the computers can be held in one hand and are called personal digital assistants. They are used as notepads, scheduling systems, and address books; Laptop computers and PCs are typically used in businesses and at home to communicate on computer networks, for word processing, to track finances, and to play games. They have large amounts of internal memory to store hundreds of programs and documents. They are equipped with a keyboard; a mouse, trackball, or other pointing device; and a video display monitor or liquid crystal display (LCD) to display information. Laptop computers usually have similar hardware and software as PCs, but they are more compact and have flat, lightweight LCD-s instead of video display monitors.
