COMPUTERS A computer is a machine that manipulates data according to a list of instructions. The first devices that resemble modern computers date to the mid-20th century (around 1940 - 1945), although the computer concept and various machines similar to computers existed earlier. Modern computers are based on tiny integrated circuits and are millions to billions of times more capable while occupying a fraction of the space. Today, simple computers may be made small enough to fit into a wristwatch and be powered from a watch battery. Personal computers, in various forms, are icons of the Information Age and are what most people think of as "a computer"; however, the most common form of computer in use today is the embedded computer. A computer can also be defined as a set of input devices, output devices and processing units. Input and output devices are integral parts of the computer system which enables the user to interact directly with the computer. Some of the input devices are Keyboard, Mouse, Barcode reader, Scanner, Webcam, Digital pen, Finger print scanner, Touch screen, Gaming devices, Microphones, etc.. INPUT DEVICE Input devices are the devices we use to put information INTO a computer. An Input device is any piece of computer hardware equipment used to provide data and control signals to a computing system. Input and output devices make up the hardware interface between a computer and the user or external world. Typical examples of input devices include keyboards and mouse. However, there are others which provide many more degrees of freedom. In general, any sensor which monitors, scans for and accepts information from the external world can be considered an input device, whether or not the information is under the direct control of a user. Any machine that feeds data into a computer. For example, a keyboard is an input device, whereas a display monitor is an output device. Input devices other than the keyboard are sometimes called alternate input devices. Mice, trackballs, and light pens are all alternate input device. Input devices can be classified according to : • The modality of input (e.g. mechanical motion, audio, visual, etc.) • whether the input is discrete (e.g. key presses) or continuous (e.g. a mouse's position, though digitized into a discrete quantity, is high-resolution enough to be thought of as continuous) • the number of degrees of freedom involved (e.g. many mice allow 2D positional input, but some devices allow 3D input, such as the Logitech Magellan Space Mouse) • 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 cursor appears. Touch screens 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) 1. KEYBOARD: As the name implies, a keyboard is basically a board of keys. Along with the mouse, the keyboard is one of the primary input devices used with a computer. The keyboard's design comes from the original typewriter keyboards, which arranged letters and numbers in a way that prevented the type-bars from getting jammed when typing quickly. This keyboard layout is known as the QWERTY design, which gets its name from the first six letters across in the upper- left-hand corner of the keyboard. Keyboard is a peripheral partially modelled after the typewriter keyboard. A keyboard typically has characters engraved or printed on the keys; in most cases, each press of a key corresponds to a single written symbol. However, to produce some symbols requires pressing and holding several keys simultaneously or in sequence; other keys do not produce any symbol, but instead affect the operation of the computer or the keyboard itself. A majority of all keyboard keys produce letters, numbers or signs (characters) that are appropriate for the operator's language. Other keys can produce actions when pressed, and other actions are available by the simultaneous pressing of more than one action key. TYPES OF Keyboard 1. Multimedia keyboards: Multimedia keyboards offer special keys for accessing music, web, and other often-used programs. They also usually have other convenient controls, such as a mute button, volume buttons or knob, and standby (sleep) button. Multimedia keyboard has a standard keyboard layout with an easy one-touch media control to play CD, DVD and MP3 media files. It integrates the web, e-mail, search and other favourite applications with a one-touch Internet access key. 2. Gaming keyboards: Some gaming keyboards offer extra function keys which can be programmed with keystroke macros. For example, ctrl+shift+y could be a keystroke that is frequently used in a certain computer game. But it is a physically awkward (or, at least, annoying) combination for the hands to reach for repeatedly. It may be very useful to assign that keystroke combination to one function key. Some keyboards (Such as the Logitech G11 or G15) have a keypad full of "G keys" to the left of the QWERTY keyboard for this purpose. The development of these keyboards was spurred by gaming, but the concept can also be very convenient in non- gaming applications, such as office work. Any keystroke combination that is awkward or annoying but frequently needed can be replaced with a "G key". The meaning of the "G key" press can automatically change depending on which application has focus, thus extending the number of macros available given a certain limited number of G keys. 3. Flexible Foldable Mini Keyboard This revolutionary keyboard is water – resistant, flexible dust and contaminant proof. The keyboard can be used in industrial environments, hospitals, libraries, marine and boating applications… infact anywhere where dust and liquids are present. The silicon-based material is impervious to almost anything! This washable, roll-able, foldable keyboard has been called “the best thing to happen to typing since the backspace key.” Ideal for travel, school or industrial applications, it fits in your briefcase, backpack or note book carrying case and you don’t have to worry about any sharp edges! The soft material allows a quick, reflexive typing action that is silent and more comfortable than hard plastic surfaces. 4. Wireless Keyboard Sometimes sitting close to your computer monitor at a desk can be uncomfortable. Other times, there may be so many tangled wires behind your computer that you are unable to organize them. Regardless of which scenario you find yourself in more often, a wireless keyboard can help. A wireless keyboard is exactly the same as a normal computer keyboard except for one major difference: Wireless keyboards transfer typing data to the computer via infrared beams. A beam of information is sent from the keyboard, as you type, to a receiver, which is plugged into the computer. This allows for a cordless experience, which eliminates the potential for another tangled cord behind your computer. It is also common for many consumers to purchase a wireless mouse to compliment a wireless keyboard. Wireless technology also allows you to place your wireless keyboard or mouse in a position that the corded-version may not reach. However, the infrared keyboard receiver must be placed in a location that is easily reachable by the infrared beam. This distance may vary from model to model, so check specifications before purchasing a wireless keyboard. If the keyboard is not pointed in the general direction of the receiver, or if the line-of-sight between the wireless keyboard and receiver is blocked, then the signal will not be transmitted to the computer. This can create a problem for the user if someone is walking between the keyboard and receiver or if the keyboard is not angled correctly. If you are sure that the space between your wireless keyboard and receiver will be relatively clutter free, a wireless keyboard can make a great addition to your home computer, freeing you up by providing more flexibility in the way you operate your computer system. 5.Smaller keyboards A standard keyboard is physically quite large, as each key must remain large enough to be easily pressed by fingers. Other types of keyboards have been proposed for small portable equipment where a standard keyboard is too large. One way to reduce the size of the keyboard is to reduce the number of keys and use chording keyer, i.e. pressing several keys simultaneously. For example, the GKOS keyboard has been designed for small wireless devices. Other two-handed alternatives more akin to a game controller, such as the AlphaGrip, are also used as a way to input data and text. Another way to reduce the size of a keyboard is to use smaller buttons and pack them closer together. Such keyboards, often called a "thumbboard" (thumbing) are used in some personal digital assistants such as the Treo and BlackBerry and some Ultra-Mobile PCs such as the OQO. 2. MOUSE: The name mouse originated at the Stanford Research Institute, derives from the resemblance of early models (which had a cord attached to the rear part of the device, In computing, a mouse (plural mouse devices or mouses) is a pointing device that functions by detecting two-dimensional motion relative to its supporting surface. Physically, a mouse consists of a small case, held under one of the user's hands, with one or more buttons. It sometimes features other elements, such as "wheels", which allow the user to perform various system- dependent operations, or extra buttons or features can add more control or dimensional input.