Computers affect your life every day and will continue to do so in the future. New uses for computers and improvements to existing technology are being developed continually.
The first question related to understanding computers and their impact on our lives is, “What is a computer?” A computer is an electronic device, operating under the control of instructions stored in its own memory unit that can accept data (input), process data arithmetically and logically, produce results (output), and store the results for future use. Most computers also include the capability to communicate by sending and receiving data to other computers and to connect to the Internet. While different definitions of a computer exist, this definition includes a wide range of devices with various capabilities. Often the term computer or computer system is used to describe a collection of devices that function together to process data.
Data is input, processed, output and stored by specific equipment called computer hardware. This equipment consists of system unit, input devices, output devices, storage devices, and communications devices.
Input devices are used to enter data into a computer. Two common input devices are the keyboard and the mouse. As the data is entered using the keyboard, it is temporarily stored in the computer’s memory and displayed on the screen of the monitor. A mouse is a type of pointing device used to select processing options or information displayed on the screen. The mouse is used to move a small symbol that appears on the screen. This symbol, called a mouse pointer or pointer, can be many shapes but is often in the shape of an arrow.
The system unit is a box-like case that contains the electronic circuits that cause the processing of data to occur. The electronic circuits usually are part of or are connected to a main circuit board called the motherboard or system board. The system board includes the central processing
unit, memory and other electronic components. The central processing unit (CPU) contains a control unit that executes the instructions that guide the computer through a task and an arithmetic/logic unit (ALU) that performs math and logic operations. The CPU is sometimes referred to as the processor.
Memory also called RAM (Random Access Memory) or main memory, temporarily stores data and program instructions when they are being processed.
Storage devices, sometimes called secondary storage or auxiliary storage devices, store instructions and data when the system unit is not using them. Storage devices often function as an input source when previously stored data is read into memory. A common storage device on personal computers is called a hard disc drive. A hard disc drive contains a high-capacity disc or discs that provide greater storage capacities than floppy discs. A CD-ROM drive uses a low-powered laser light to read data from removable CD-ROMs.
Communication devices enable a computer to connect to other computers. A modem is a communications device used to connect computers over telephone lines. A network interface card is used to connect computers that are relatively close together, such as those in the same building. A group of computers connected together is called a network.
The devices just discussed are only some of the many types of input, output, storage, and communications devices that can be part of a computer system. A general term for any device connected to the system unit is peripheral device.
Whether small or large, computers can perform four general operations.