Basic Of Computer, I / O Devices
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Wikipedia
A computer is a digital electronic machine that can be programmed to carry out sequences of arithmetic or logical operations (computation) automatically. Modern computers can perform generic sets of operations known as programs. These programs enable computers to perform a wide range of tasks. A computer system is a “complete” computer that includes the hardware, operating system (main software), and peripheral equipment needed and used for “full” operation. This term may also refer to a group of computers that are linked and function together, such as a computer network or computer cluster.
A broad range of industrial and consumer products use computers as control systems. Simple special-purpose devices like microwave ovens and remote controls are included, as are factory devices like industrial robots and computer-aided design, as well as general-purpose devices like personal computers and mobile devices like smartphones. Computers power the Internet, which links billions of other computers and users.
Early computers were meant to be used only for calculations. Simple manual instruments like the abacus have aided people in doing calculations since ancient times. Early in the Industrial Revolution, some mechanical devices were built to automate long tedious tasks, such as guiding patterns for looms. More sophisticated electrical machines did specialized analog calculations in the early 20th century. The first digital electronic calculating machines were developed during World War II. The first semiconductor transistors in the late 1940s were followed by the silicon-based MOSFET (MOS transistor) and monolithic integrated circuit (IC) chip technologies in the late 1950s, leading to the microprocessor and the microcomputer revolution in the 1970s. The speed, power and versatility of computers have been increasing dramatically ever since then, with transistor counts increasing at a rapid pace (as predicted by Moore’s law), leading to the Digital Revolution during the late 20th to early 21st centuries.
Conventionally, a modern computer consists of at least one processing element, typically a central processing unit (CPU) in the form of a microprocessor, along with some type of computer memory, typically semiconductor memory chips. The processing element carries out arithmetic and logical operations, and a sequencing and control unit can change the order of operations in response to stored information. Peripheral devices include input devices (keyboards, mice, joystick, etc.), output devices (monitor screens, printers, etc.), and input/output devices that perform both functions (e.g., the 2000s-era touchscreen). Peripheral devices allow information to be retrieved from an external source and they enable the result of operations to be saved and retrieved.
Devices have been used to aid computation for thousands of years, mostly using one-to-one correspondence with fingers. The earliest counting device was probably a form of tally stick. Later record keeping aids throughout the Fertile Crescent included calculi (clay spheres, cones, etc.) which represented counts of items, probably livestock or grains, sealed in hollow unbaked clay containers. The use of counting rods is one example.
In computing, an input device is a piece of equipment used to provide data and control signals to an information processing system, such as a computer or information appliance. Examples of input devices include keyboards, mouse, scanners, cameras, joysticks, and microphones.
Input devices can be categorized based on:
- modality of input (e.g., mechanical motion, audio, visual, etc.)
- whether the input is discrete (e.g., pressing of key) or continuous (e.g., a mouse’s position, though digitized into a discrete quantity, is fast enough to be considered continuous)
- the number of degrees of freedom involved (e.g., two-dimensional traditional mice, or three-dimensional navigators designed for CAD applications)A keyboard is a human interface device which is represented as a layout of buttons. Each button, or key, can be used to either input an alphanumeric character to a computer, or to call upon a particular function of the computer. It acts as the main text entry interface for most users.
Keyboards are available in many form factors, depending on the use case. Standard keyboards can be categorized by its size and number of keys, and the type of switch it employs. Other keyboards cater to specific use cases, such as a numeric keypad or a keyer.
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Desktop keyboards are typically large, often have full key travel distance, and features such as multimedia keys and a numeric keypad. Keyboards on laptops and tablets typically compromise on comfort to achieve a thin figure.There are various switch technologies used in modern keyboards, such as mechanical switches (which use springs), scissor switches (usually found on a laptop keyboard), or a membrane.
Other keyboards do not have physical keys, such as a virtual keyboard, or a projection keyboard.
A pointing device allows a user to input spatial data to a computer. It is commonly used as a simple and intuitive way to select items on a computer screen on a graphical user interface (GUI), either by moving a mouse pointer, or, in the case of a touch screen, by physically touching the item on screen. Common pointing devices include mice, touchpads, and touch screens.
Whereas mice operate by detecting their displacement on a surface, analog devices, such as 3D mice, joysticks, or pointing sticks, function by reporting their angle of deflection.
Pointing devices can be classified on:
- Whether the input is direct or indirect. With direct input, the input space coincides with the display space, i.e. pointing is done in the space where visual feedback or the pointer appears. Touchscreens and light pens involve direct input. Examples involving indirect input include the mouse and trackball.
- Whether the positional information is absolute (e.g. on a touch screen) or relative (e.g., with a mouse that can be lifted and repositioned)
Direct input is almost necessarily absolute, but indirect input may be either absolute or relative. For example, digitizing graphics tablets that do not have an embedded screen involve indirect input and sense absolute positions and are often run in an absolute input mode, but they may also be set up to simulate a relative input mode like that of a touch pad, where the stylus or puck can be lifted and repositioned. Embedded LCD tablets, which are also referred to as graphics tablet monitors, are the extension of digitizing graphics tablets. They enable users to see the real-time positions via the screen while being used.
In computing, input/output/(*.*)., or Clear Text, refers to the communication between a digital processing system (such as a computer or an embedded system), and the outside world – possibly a human, another processing system or a device.
Inputs are the signals or data received by the system, and outputs are the signals or data sent from it.
I/O devices are used by a person (or other system) to communicate with the digital processing system. For instance, keyboards and mice are considered input devices of a computer, while monitors and printers are considered output devices of a computer. Devices for communication between computers, such as modems and network cards, typically serve for both input and output.
Note that the description of a device as either input or output depends on how it is viewed. Mouses 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.)
Computers only work with digital information, any input that a computer receives must be digitalised.
In computer science, the general meaning of input is to provide or give something to the computer, in other words, when a computer or device is receiving a command or signal from outer sources, the event is referred to as input to the device.
Some computer devices can also be categorized as input devices because we use these devices to send instructions to the computer, some common examples of computer input devices are:
- Mouse
- Keyboard
- Touchscreen
- Microphone
- Webcam
- Softcam
- Touchpad
- Trackpad
- Image scanner
- Trackball
Also some internal components of computer are input components to other components, like the power-on button of a computer is input component for the processor or the power supply, because it takes user input and sends it to other components for further processing.
In many computer languages the keyword “input” is used as a special keyword or function, such as in Visual Basic or Python. The command “input” is used to give the machine the data it has to process.