Most computers are meant to be used by only one person at a time. Such computers are often shared by several people (such as those in your school’s computer lab), but only one user can work with the machine at any given moment (sec Figure 1 A.4).
The six primary types of computers in this category arc
≫ Desktop computers
≫ Notebook computers
≫ Tablet computers
≫ Handheld computers
≫ Smart phones
These systems are all examples of personal computers (PCs) a term that refers to any computer system that is designed for use by a single person. Personal computers arc also called Microcomputer because they are among the smallest computers created for people to use. Note, however, that the term personal computer or PC is most often used to describe desktop computers, which you will learn about in the following section. Although personal computers are used by individuals, they also can be connected together to create networks. In fact, networking has become one of the most important jobs of personal computers, and even tiny handheld computers can now be connected to networks. You will learn about computer networks in Chapter 7, “Networks."
The most common type of personal computer is the desktop computer—a PC that is designed to sit on (or under) a desk or table. These are the systems you sec all around you, in schools, homes, and offices, and they are the main focus of this book. Today's desktop computers are far more powerful than those of just a few years ago, and are used for an amazing array of tasks. Not only do these machines enable people to do their jobs with greater ease and efficiency, but they can be used to communicate, produce music, edit photographs and videos, play sophisticated games, and much more. Used by everyone from preschoolers to nuclear physicists, desktop computers arc indispensable for learning, work, and play.
As its name implies, a desktop computer is a full-size computer that is too big to be carried around. The main component of a desktop PC is the system unit, which is the case that houses the computer’s critical parts, such as its processing and storage devices. There are two common designs for desktop computers. The more traditional desktop model features a horizontally oriented system unit, which usually lies flat on the top of the user’s desk. Many users place their monitor on top of the system unit. Vertically oriented tower models have become the more popular style of desktop system. This design allows the user to place the system unit next to or under the desk, if desired.
A workstation is a specialized, single-user computer that typically has more power and features than a standard desktop PC. These machines are popular among scientists, engineers, and animators who need a system with greater-than-average speed and the power to perform sophisticated tasks. Workstations often have large, high-resolution monitors and accelerated graphics handling capabilities, making them suitable for advanced architectural or engineering design, modeling, animation, and video editing.
Notebook computers, as their name implies, approximate the shape of an 8.5-by-ll-inch notebook and easily fit inside a briefcase. Because people frequently set these devices on their lap, they are also called laptop computers. Notebook computers can operate on alternating current or special batteries. These amazing devices generally weigh less than eight pounds, and some even weigh less than three pounds! During use, the computer’s lid is raised to reveal a thin monitor and a keyboard. When not in use, the device folds up for easy storage. Notebooks arc fully functional microcomputers; the people who use them need the power of a full-size desktop computer wherever they go (see Figure I A.10). Because of their portability, notebook PCs fall into a category of devices called mobile computers—systems small enough to be carried by their user.
Some notebook systems are designed to be plugged into a docking station, which may include a large monitor, a full-size keyboard and mouse, or other devices. Docking stations also provide additional ports that enable the notebook computer to be connected to different devices or a network in the same manner as a desktop system.
The tablet PC is the newest development in portable, full-featured computers. Tablet PCs offer all the functionality of a notebook PC, but they are lighter and can accept input from a special pen—called a stylus or a digital pen—that is used to tap or write directly on the screen. Many tablet PCs also have a built-in microphone and special software that accepts input from the user's voice. A few models even have a fold-out keyboard, so they can be transformed into a standard notebook PC. Tablet PCs run specialized versions of standard programs and can be connected to a network. Some models also can be connected to a keyboard and a full-size monitor.
Handheld personal computers are computing devices small enough to fit in your hand. A popular type of handheld computer is the personal digital assistant (PDA). A PDA is no larger than a small appointment book and is normally used for special applications, such as taking notes, displaying telephone numbers and addresses, and keeping track of dates or agendas. Many PDAs can be connected to larger computers to exchange data. Most PDAs come with a pen that lets the user write on the screen. Some handheld computers feature tiny built-in keyboards or microphones that allow voice input. Many PDAs let the user access the Internet through a wireless connection, and several models offer features such as cellular telephones, cameras, music players, and global positioning systems.
Some cellular phones double as miniature PCs. Because these phones offer advanced features not typically found in cellular phones, they are sometimes called smart phones. These features can include Web and c-mail access, special software such as personal organizers, or special hardware such as digital cameras or music players. Some models even break in half to reveal a miniature keyboard.