INPUT AND OUTPUT DEVICES
In computing, input/output, or I/O, refers to the communication between an information processing system (such as a computer), and the outside world possibly a human, or another information processing system. Inputs are the signals or data received by the system, and outputs are the signals or data sent from it. The term can also be used as part of an action; to "perform I/O" is to perform an input or output operation. I/O devices are used by a person (or other system) to communicate with a computer. For instance, a keyboard or a mouse may be an input device for a computer, while monitors and printers are considered output devices for a computer. Devices for communication between computers, such as modems and network cards, typically serve for both input and output. Note that the designation of a device as either input or output depends on the perspective. Mouse and keyboards take as input physical movement that the human user outputs and convert it into signals that a computer can understand. The output from these devices is input for the computer. Similarly, printers and monitors take as input signals that a computer outputs. They then convert these signals into representations that human users can see or read. For a human user the process of reading or seeing these representations is receiving input. These interactions between computers and humans is studied in a field called human–computer interaction. In computer architecture, the combination of the CPU and main memory (i.e. memory that the CPU can read and write to directly, with individual instructions) is considered the brain of a computer, and from that point of view any transfer of information from or to that combination, for example to or from a disk drive, is considered I/O. The CPU and its supporting circuitry provide memory-mapped I/O that is used in low-level computer programming in the implementation of device drivers. An I/O algorithm is one designed to exploit locality and perform efficiently when data reside on secondary storage, such as a disk drive.
Input is any data or instructions entered into the memory of a computer. An Input device is any hardware component that allows a user to enter data and instructions into a computer. The following is a list of the most common input devices which are nowadays found in a computer system.
A keyboard contains keys that allow a user to enter data and instructions into the computer. All computer keyboards have a typing area that includes the letters of the alphabet, numbers, punctuation marks, and other basic keys. Many desktop computer keyboards also have a numeric keypad located on the right side of the keyboard. On notebook and many handheld computers, the keyboard is built into the top of the system unit. A standard computer keyboard is called a QWERTY keyboard because of the layout of its typing area which is similar to that of a typewriter.
Advantages of using keyboards for data input include
_ It is not necessary to buy additional equipment because most computer systems are normally supplied with keyboards.
_ Entering data and instructions with keyboards is generally faster than with pointing devices.
Disadvantages of using keyboards for data input include
_ It takes a lot of time to practice in order to type quickly and accurately. _ Typing speeds are still very slow when compared with computer speeds.
A mouse is the most widely used pointing device with a GUI
environment on personal computers. A mechanical mouse has a
rubber ball on its underside to detect movement of the mouse. An optical mouse uses devices that emit and sense light to detect the mouse's movement. A cordless mouse (either mechanical or optical) transmits data using wireless technology such as radio waves or infrared light waves. Advantages of using a mouse include
_ A mouse is user-friendly for computer beginners.
_ A mouse is easy and convenient to use...
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