Input Device: Mouse

In computing, a mouse is a pointing device that functions by detecting two-dimensional motion relative to its supporting surface. Physically, a mouse consists of an object 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 that can add more control or dimensional input. The mouse's motion typically translates into the motion of a cursor on a display, which allows for fine control of a graphical user interface.

1. Mechanical mouse : It is a hand held pointing device. A mechanical mouse has a rotating ball on its base. It is rolled over a flat surface or on a mouse pad. The cursor on the screen moves in the direction of mouse's movement. Two rotating wheels placed at right angles to each other inside the mouse detect the direction of movement. Each wheel is connected to a shaft encoder,which limits electrical pulses for every incremental movement of wheel. The pulse transmitted by the mouse determines the distance moved.

There may be two or three buttons on a mouse. The button on the left is for selecting items on the screen and the button on the right is normally used for displaying and selecting pop-up menus. 

2. Optical Mouse : The optical mouse has a light beam instead of a rotating ball to direct movement across a specially-patterned mouse pad. the optical mouse use LEDs and photo detectors to trap its movements. Optical mice make use of one or more light-emitting diodes (LEDs) and an imaging array of photodiodes to detect movement relative to the underlying surface, rather than internal moving parts as does a mechanical mouse. A Laser mouse is an optical mouse that uses coherent (Laser) light.

3. Inertial and gyroscopic mouse : Often called "air mice" since they do not require a surface to operate, inertial mice use a tuning fork or other accelerometer to detect rotary movement for every axis supported. The most common models (manufactured by Logitech and Gyration) work using 2 degrees of rotational freedom and are insensitive to spatial translation. The user requires only small wrist rotations to move the cursor, reducing user fatigue or "gorilla arm". Usually cordless, they often have a switch to deactivate the movement circuitry between use, allowing the user freedom of movement without affecting the cursor position.

4. 3D mouse : Also known as bats, flying mice, or wands, these devices generally function through ultrasound and provide at least three degrees of freedom. Probably the best known example would be 3DConnexion/Logitech's SpaceMouse from the early 1990s.

In the late 1990s Kantek introduced the 3D RingMouse. This wireless mouse was worn on a ring around a finger, which enabled the thumb to access three buttons. The mouse was tracked in three dimensions by a base station. Despite a certain appeal, it was finally discontinued because it did not provide sufficient resolution.

Input Device : Scanner

In computing, an image scanner—often abbreviated to just scanner— is a device that optically scans images, printed text, handwriting, or an object, and converts it to a digital image. Common examples found in offices are variations of the desktop (or flatbed) scanner where the document is placed on a glass window for scanning. Hand-held scanners, where the device is moved by hand, have evolved from text scanning "wands" to 3D scanners used for industrial design, reverse engineering, test and measurement, gaming and other applications. Mechanically driven scanners that move the document are typically used for large-format documents, where a flatbed design would be impractical.

Modern scanners typically use a charge-coupled device (CCD) or a Contact Image Sensor (CIS) as the image sensor, whereas older drum scanners use a photomultiplier tube as the image sensor. A rotary scanner, used for high-speed document scanning, is another type of drum scanner, using a CCD array instead of a photomultiplier. Other types of scanners are planetary scanners, which take photographs of books and documents, and 3D scanners, for producing three-dimensional models of objects.

Another category of scanner is digital camera scanners, which are based on the concept of reprographic cameras. Due to increasing resolution and new features such as anti-shake, digital cameras have become an attractive alternative to regular scanners. While still having disadvantages compared to traditional scanners (such as distortion, reflections, shadows, low contrast), digital cameras offer advantages such as speed, portability and gentle digitizing of thick documents without damaging the book spine. New scanning technologies are combining 3D scanners with digital cameras to create full-color, photo-realistic 3D models of objects.

In the biomedical research area, detection devices for DNA microarrays are called scanners as well. These scanners are high-resolution systems (up to 1 µm/ pixel), similar to microscopes. The detection is done via CCD or a photomultiplier tube (PMT).

Scanners are input devices which are capable of recognizing marks or characters. They are capable of entering information directly from the computer without the user keying it in. They are fast and accurate. the two major types of scanners are OCR (Optical character Reader) and MICR (Magnetic Ink character Reader)

OCR (Optical Character Reader)

These scanners are capable of detecting alphabetic and numeric characters. If the characters are handwritten, they should be of standard size and there should be no stylish loops in the letters and lines. The characters should be properly connected if hand-written or in characters of a special font called OCR, if typed. OCR devices examine each character as if they were made up of a collection of minute spots.

OMR (Optical Mark Reader)

These scanners are capable of recognizing a pen or pencil mark made on a paper. An OMR scanner can sense the presence and absence of a mark. When you appear in objective-type tests or examinations in future, where you have to mark your answers by filling up a square box or a circular shape with a pencil, out of all the square/circular shapes provided, to indicate your choice of answer - you will know that these types of answer sheets are to be fed directly in to the computer to be scanned by an OMR.

MICR (Magnetic Ink character Reader)

MICR was developed to assist the banking industry to process a large number of cheques everyday. The bank identification code and the customer's account number are pre-printed with a special ink on every cheque. the ink contains magnetizable particles of iron oxide. a magnetic ink character reader reads these characters by examining their shapes with the help of a matrix, and sends this information to the system.

Input Device: Digitizer

A graphics tablet (or digitizer, digitizing tablet, graphics pad, drawing tablet) is a computer input device that allows one to hand-draw images and graphics, similar to the way one draws images with a pencil and paper. These tablets may also be used to capture data or handwritten signatures. It can also be used to trace an image from a piece of paper which is taped or otherwise secured to the surface. Capturing data in this way, either by tracing or entering the corners of linear poly-lines or shapes is called digitizing.

A graphics tablet (also called pen pad or digitizer) consists of a flat surface upon which the user may "draw" or trace an image using an attached stylus, a pen-like drawing apparatus. The image generally does not appear on the tablet itself but, rather, is displayed on the computer monitor. Some tablets, however, come as a functioning secondary computer screen that you can interact with images directly by using the stylus.

A digitizer or tablet is a surface over which a stylus (similar to a pencil) or hand cursor is moved. The location of the hand cursor or stylus is available to the computer system. The size of the tablet, a square block, varies from 10 inches to 5 sq. ft. depending upon application. The stylus senses a position through a transducer (pressure-sensitive switch) so that the movement of the stylus over the tablet causes a corresponding line on the CRT screen.

Input Device : Joystick

The joystick is an input device used for playing games. It is a stick which can be moved lefr, right, forward and backward. The movements are sensed by a potentiometer. As the stick moves, the movements are translated into binary instructions with the help of electrical contacts in its base.

A popular variation of the joystick used on modern video game consoles is the analog stick.

The joystick has been the principal flight control in the cockpit of many aircraft, particularly military fast jets, either as a center stick or side-stick.

Joysticks are also used for controlling machines such as cranes, trucks, underwater unmanned vehicles, wheelchairs, surveillance cameras and zero turning radius lawn mowers. Miniature finger-operated joysticks have been adopted as input devices for smaller electronic equipment such as mobile phones.

The name "joystick" is thought to originate with early 20th century French pilot Robert Esnault-Pelterie. There are also competing claims on behalf of fellow pilots Robert Loraine, James Henry Joyce and A. E. George. Loraine is credited with entering the term "joystick" in his diary in 1909 when he went to Pau to learn to fly at Bleriot's school. George was a pioneer aviator who with his colleague Jobling built and flew a biplane at Newcastle in England in 1910. He is alleged to have invented the "George Stick" which became more popularly known as the joystick.

Input Device:Light Pen

A light pen is a computer input device in the form of a light-sensitive wand used in conjunction with a computer's CRT TV set or monitor. It allows the user to point to displayed objects, or draw on the screen, in a similar way to a touch screen but with greater positional accuracy.

A light pen is fairly simple to implement. Just like a light gun, a light pen works by sensing the sudden small change in brightness of a point on the screen when the electron gun refreshes that spot. By noting exactly where the scanning has reached at that moment, the X,Y position of the pen can be resolved. This is usually achieved by the light pen causing an interrupt, at which point the scan position can be read from a special register, or computed from a counter or timer. The pen position is updated on every refresh of the screen.

The light pen is a photosensitive pen. It is also a poinnting device, capable of sensing a position on the screen. When a light pen's tip is moved over the screen surface, its photocell sensing element detects light coming from the screen. Corresponding signals are sent to the processor that identifies the point (pixel) on the screen. A light pen is used to draw images onscreen.

Input Device : Keyboard

The following functions are carried out by input devices:

1. They accept data from the outside world.

2. They convert this data into binary form acceptable to the machine.

3. They send data in binary form to the computers for further processing.

A keyboard looks like a typewriter. It enables one to enter data into a computer. Computer keyboards are similar to electronic-typewriter keyboards but contain additional keys. The keys on computer keyboards are often classified as follows:

  1. Alphanumeric keys - Letters and numbers

  2. Punctuation keys - comma, period, semicolon and so on.

  3. Special keys - function keys, control keys, arrow keys, caps lock key, etc.

In normal usage, the keyboard is used to type text and numbers into a word processor, text editor or other program. In a modern computer, the interpretation of key presses is generally left to the software. A computer keyboard distinguishes each physical key from every other and reports all key presses to the controlling software.

Keyboards are also used for computer gaming, either with regular keyboards or by using keyboards with special gaming features, which can expedite frequently used keystroke combinations. A keyboard is also used to give commands to the operating system of a computer, such as Windows' Control-Alt-Delete combination, which brings up a task window or shuts down the machine. It is the only way to enter commands on a command-line interface.

Input / Output with Files

C++ has support both for input and output with files through the following classes:

                ofstream: File class for writing operations (derived from ostream)

                ifstream: File class for reading operations (derived from istream)

                fstream: File class for both reading and writing operations (derived from iostream)

Open a file

The first operation generally done on an object of one of these classes is to associate it to a real file, that is to say, to open a file. The open file is represented within the program by a stream object (an instantiation of one of these classes) and any input or output performed on this stream object will be applied to the physical file. LEARN MORE>>