A computer system consists of two broad categories of components: hardware and software. The combination of hardware and software that makes up a particular system depends on the user's requirements, and given the number of hardware devices and software programs available in the marketplace, users can configure all kinds of possible setups. Manufacturers typically offer a system unit, monitor, and keyboard package, leaving the choice of mouse, printer, and other hardware devices up to the buyer. PC system units are usually preloaded with the Microsoft Windows operating system software plus some basic programs such as a word processing program.
Computer Hardware
Hardware includes all of the physical components that make up the system unit plus the other devices connected to it, such as a keyboard or monitor. These con- nected devices are referred to as peripheral devices because they are outside. or to, the computer. Examples include a keyboard, mouse, camera, and printer. Some peripheral devices, such as a monitor and hard disk drive, are essential components of a personal computer system. Hardware devices are grouped into the following categories:
- system unit
- input devices output devices
- storage devices
- communications devices
The System Unit
The system unit is a relatively small plastic or metal cabinet housing the electronic components that process data into information. Inside the cabinet is the main circuit board, called the motherboard, which provides for the installation and connection of other electronic components (see Figure 1-7). Once installed on the motherboard, the components can communicate with each other, thereby allowing data to be processed into information.
The main components of the motherboard are the central processing unit (CPU), also called the microprocessor (or simply processor), and internal memory. The CPU processor consists of one or more electronic chips that read, interpret, and execute the instructions that operate the computer and perform specific computing tasks. When a program is executed, the processor temporarily stores the program's instructions and the data the instructions need into the computer's memory. Main memory, also called primary storage or random access memory (RAM), consists of small electronic chips that provide temporary storage for instructions and data during processing.
Input Devices
An input device is a hardware device that allows users to enter program instructions, data, and commands into a computer) The program or application being used determines the type of input device needed.(Common input devices are the keyboard, mouse, and microphone!
Output Devices
An output device is a device that makes information available to the user. Popular output devices include display screens (monitors), printers, television screens, and speakers) Some output devices, such as a printer, produce output in hard copy (tangible) form, such as on paper or plastic. Other output devices, such as a monitor, produce output in soft copy (intangible) form that can be viewed, but not physically handled.
Storage Devices
Unlike memory that stores instructions and data temporarily during processing, a storage device, often called storage medium or secondary storage, provides for the permanent storage of programs, data, and information. Once stored, information can be retrieved, modified, displayed, imported. exported, copied, or printed.
A storage device itself records programs, data, and/or information to a storage medium and retrieves them from the storage medium. For example, a CD drive (storage device) would write data to a CD (storage medium), and the CD drive would retrieve data from the CD later.
Communications Devices
A communications device makes it possible for a user to communicate with another computer and to exchange instructions, data, and information with other computer users. The most popular communications device is a modem) an electronic device capable of converting computer-readable information into a form that can be transmitted and received over communications systems, such as standard telephone lines. Due to increased speeds, broadband Internet access (via cable and DSL) has been replacing dial-up acess over the past few years. Nielson Online reported that as of June 2008, only 9.5 percent of U.S. Internet users connecting from home had a dial-up connection, while 90.5 percent had a broadband connection.