A keyboard is the most common input device. Using a keyboard, the user can type the text and execute commands. Keyboard is designed to resemble a regular typewriter with a few additional keys. Data is entered into the computer by simply pressing various keys. The layout of a keyboard comes in various styles but QWERTY is the most common layout. The layout of the keyboard has changed very little ever since it was introduced. In fact, the most common change in its technology has simply been the natural evolution of adding more keys that provide additional functionality.

The number of keys on a keyboard varies from 82 keys to 108 keys. Portable computers such as laptops quite often have custom keyboards that have slightly different key arrangements from a standard keyboard. Pointing devices are the input devices by which we can point out and select the items rapidly from the multiple options displayed on the screen. These devices can also be used to create graphic elements on the screen such as lines, curves and freehand shapes. The most common types of pointing devices available are:

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a) Mouse b) Trackball c) Joystick d) Touch Screen e) Light Pen ) Touch Pad a) Mouse A mouse is a small hand-held pointing device, which is used to create graphic elements on the screen such as lines, curves, and freehand shapes. It is also used to run a program and pull down a menu in GUI (Graphic User Interface) base computer system. It is rectangular shaped with a rubber ball embedded at its lower side and buttons on the top. Usually a mouse contains two or three buttons, which can be used to input commands or instructions. A mechanical mouse uses a rubber ball at the bottom surface, which rotates as the mouse along a flat surface to move the cursor.

It is the most common and expensive pointing device. Microsoft, IBM and Logitech are some well-known makers of the mechanical mouse. An optical mouse uses the light beam instead of rotating ball to detect the movement across a especially patterned mouse pad. As the mouse rolls the mouse on a flat surface, the cursor on the screen also moves in the direction of the mouse’s movement. It is more expensive in comparison with the mechanical mouse. Modern optical mouse are accurate and often do not need a mouse pad. A track ball is another pointing device that uses a ball which is settled in a square cardle.

In general, a track ball is just like a turned upside down a mouse. The ball is rolled by fingers to move the cursor around the screen. A track ball requires less space than a mouse for operation because the whole device is not moved for moving the curser. It is often attached to or inbuilt into the keyboard. The trackball built into the keyboard are commonly used in laptop computers, because the mouse is not practical for laptop users in a small space. This pointing device comes in various shapes but with the same functionality. It works like a mouse.

With the new Wedge Touch Mouse, you can comfortably navigate Windows 8 using Microsoft’s touch technology—while at the same time wowing those around you with a mouse that looks and feels like no other. It packs full functionality into a compact frame that’s great for your mobile lifestyle. Small enough to fit in your pocket, it’s the perfect companion for your laptop or tablet when you’re on the go. Plus the artful, minimalist design (complemented by high-quality materials and craftsmanship) gives you fluid, four-way touch scrolling and navigation in every direction.

Not only is Wedge Touch Mouse compact, it doesn’t come with cables or USB transceivers. Just turn it on and connect it to your Bluetooth-enabled laptop or tablet. Additionally, BlueTrack technology means it tracks on virtually any surface, whether you’re at a conference or a coffee shop. Wedge Touch Mouse even knows how to conserve energy. Joystick is a device that moves in all directions and controls the movement of the cursor on the screen. The joystick offers three types of controls. • Digital control • Glide control • Direct control Digital control allows in a limited movement in a number of directions such as up, down, left and right.

Glide and direct controls allow movements in all directions (360 degree). It has some pushing buttons and a circuit board which is placed under the stick. Joysticks are mainly used for computer games and for other applications such as training simulators, etc. A light pen is a hand-held electro-optical pointing device which is connected to the computer by a cable. When it touches to a connected computer monitor, it will allow the computer to determine where on that screen the pen is pointed. It facilitates drawing images and selects objects on the display screen by directly pointing to the objects with the pen.

Light pens give the user the full range of mouse capabilities, without using the pad and any horizontal surface. Using light pens, the user can interact more easily with applications in such modes as dragging and dropping or highlighting. It is very popular for graphic work in engineering like CAD (Computer Aided Design). A touch screen is a special kind of screen device, which is placed on the computer monitor in order to allow the direct selection or activation of the computer’s information, when somebody touches the screen.

Essentially, it registers the input when a finger or other object to touch the screen. Touch screen is normally used to touch the screen. Touch screen is normally used to access the information with minimum effort. Typically, they are used in information-providing systems like the hospital, airlines, railway reservation counters, amusement parks, etc. A touch pad is one of the latest pointing devices. It looks like a small gray window, about two inches wide. It is used in portable computer such as laptop and notebook to substitute the mouse.

It has two buttons below or above the pads which work like the mouse buttons. You can move the cursor on the screen by making a finger or other object along the pad and one can also click by tapping a finger on the touch pad, and drag with a tap in the continuous pointing scale. A digital camera is also an input device which stores pictures digitally rather than recording them on a film. Once a picture has been taken that store on its chip memory, the picture can be downloaded to computer system and then manipulated with an image editing software. Then it can be printed.

The major advantage of digital cameras is that making photos is both inexpensive and fast because there is no film processing. A scanner scans an image and transforms the image to ASCII codes and graphics. This can be edited, manipulated, combined and then printed. Scanners use a light beam to scan the input data. If the data to be scanned is an image, it can be changed by using the special image editing software. If the image is a page of a text, then the special optical character recognition software must be used to convert the image of letters in the text and this can be edited by using a word processor.

Most of the scanners come with a utility program that allows it to communicate with the computer and save the scanned image as a graphic file on the computer. Flatbed scanners will take up some desktop space but provide a lot bang for the buck. They look like miniature printers with a flip up cover protecting the glass platen. Depending on its size, a flatbed scanner can fit standard or legal sized documents, and flexible cover allows you to scan large items such as books. Optical Character Recognition is a process of scanning printed pages as image on a flatbed scanner using OCR software which recognizes the letters as ASCII text.

The device used for this technology is called optical reader. Optical Mark Recognition is the process of recognizing a pre-specified type of marks made by pencils or pen on the paper. This type of technology is used to evaluate the papers of competitive examination. Optical mark reading is done by special device called optical mark reader. Magnetic-Ink Character Recognition technology is used by the banking industry for faster processing of the large volume of cheques. This technology also ensures accuracy of data entry, because most of the information is pre-printed on the cheque and is directly fed to the computer.

Magnetic ink character reader is a device used in the technology. Graphic digitizer is an input device, which is used for converting pictures, maps and drawings into digital form for storage in computers. A digitizer consists of a digital tablet associated with a stylus. The digitizing tablet is a flat surface, which contains hundreds of fine copper wires forming a grid. Processing devices in a computer are responsible for controlling the storage and retrieval of information. The central processing unit (CPU) is the heart and brain of the computer.

This one component, or “chip,” is responsible for all primary number crunching and data management. It is truly the center piece of any computer. It is so important that whole generations of computer technology are based and measured on each “new and improved” version of the CPU. When we refer to the CPU, we are usually speaking of the processor. However, the CPU requires several other components that support it with the management of data to operate. These components, when working in harmony, make up the primary elements of the CPU we know today.

A motherboard is the main printed circuit board (PCB) found in computers and other expandable systems. It holds many of the crucial electronic components of the system, such as the central processing unit (CPU) and memory, and provides connectors for other peripherals. Unlike a backplane, a motherboard contains significant sub-systems such as the processor. A chipset is a set of electronic components in an integrated circuit that manage the data flow between the processor, memory and peripherals. It is usually found in the motherboard of a computer. Chipsets are usually designed to work with a specific family of microprocessors.

Because it controls communications between the processor and external devices, the chipset plays a crucial role in determining system performance. A data bus is a computer subsystem that allows for the transferring of data from one component to another on a motherboard or system board, or between two computers. This can include transferring data to and from the memory, or from the central processing unit (CPU) to other components. An address bus is a group of parallel conductors (circuit traces) found on the motherboard and used by the CPU to “address” memory locations.

Determines which information is sent to, or received from, the data bus. A clock establishes the maximum speed at which the processor can execute commands. Not to be confused with the clock that keeps the date and time. Specialized sockets that allow additional devices called expansion cards or, less commonly, circuit boards, to be attached to the motherboard. Used to expand or customize a computer, they are extensions of the computer’s bus system. Random access memory (RAM) functions as a short-term memory for computer.

It provides temporary data storage and it is accessible through the CPU (central processing unit). RAM has the potential of being retrieved while a computer is on only. An output device is any piece of computer hardware equipment used to communicate the results of data processing carried out by an information processing system (such as computer) which converts the electronically generated information into human-readable form. A monitor is a computer display and related parts packaged in a physical unit that is separate from other parts of the computer.

Notebook computers on't have monitors because all the display and related parts are integrated into the same physical unit with the rest of the computer. In practice, the terms monitor and display are used interchangeably. Computer speakers, or multimedia speakers were introduced by altec lansing in 1990. They are speakers external to a computer that disable the lower fidelity built-in speaker. They often have a low-power internal amplifier. The standard audio connection is a 3. 5 mm (approximately 1/8 inch) stereo phone connector often color-coded lime green (following the PC 99standard) for computer sound cards.

A few use an RCA connector for input. There are also USB speakers which are powered from the 5 volts at 500 milliamps provided by the USB port, allowing about 2. 5 watts of output power. A printer is a device that accepts text and graphic output from a computer and transfers the information to paper, usually to standard size sheets of paper. Printers are sometimes sold with computers, but more frequently are purchased separately. Printers vary in size, speed, sophistication, and cost. In general, more expensive printers are used for higher-resolution color printing.

A plotter is a printer that interprets commands from a computer to make line drawings on paper with one or more automated pens. Unlike a regular printer , the plotter can draw continuous point-to-point lines directly from vector graphics files or commands. There are a number of different types of plotters: a drum plotter draws on paper wrapped around a drum which turns to produce one direction of the plot, while the pens move to provide the other direction; a flatbed plotter draws on paper placed on a flat surface; and an electrostatic plotter draws on negatively charged paper with positively charged toner.

A LCD projector is a type of video projector for displaying video, images or computer data on a screen or other flat surface. It is a modern equivalent of the slide projector or overhead projector. To display images, LCD projectors typically send light from a metal-halide lamp through a prism or series of dichroic filters that separates light to three polysilicon panels – one each for the red, green and blue components of the video signal.