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What Is Computer A computer is a device that accepts information (in the form of digitalized data) and manipulates it for some result based on a program or sequence of instructions on how the data is to be processed. Complex computers also include the means for storing data (including the program, which is also a form of data) for some necessary duration. A program may be invariable and built into the computer (and called logic circuitry as it is on microprocessors) or different programs may be provided to the computer (loaded into its storage and then started by an administrator or user). Today's computers have both kinds of programming. Most histories of the modern computer begin with the Analytical Engine envisioned by Charles Babbage following the mathematical ideas of George Boole, the mathematician who first stated the principles of logic inherent in today's digital computer. Babbage's assistant and collaborator, Ada Lovelace, is said to have introduced the ideas of program loops and subroutines and is sometimes considered the first programmer. Apart from mechanical calculators, the first really useable computers began with the vacuum tube, accelerated with the invention of the transistor, which then became embedded in large numbers in integrated circuits, ultimately making possible the relatively low-cost personal computer. Modern computers inherently follow the ideas of the stored program laid out by John von Neumann in 1945. Essentially, the program is read by the computer one instruction at a time, an operation is performed, and the computer then reads in the next instruction, and so on. Recently, computers and programs have been devised that allow multiple programs (and computers) to work on the same problem at the same time in parallel. With the advent of the Internet and higher bandwidth data transmission, programs and data that are part of the same overall project can be distributed over a network and embody the Sun Microsystems slogan: "The network is the computer." Peripheral Devices In computer hardware, a peripheral device is any device attached to a computer in order to expand its functionality. Some of the more common peripheral devices are printers, scanners, disk drives, tape drives, microphones, speakers, and cameras. ... n computing, any item connected to a computer's central processing unit (CPU). Typical peripherals include keyboard, mouse, monitor, and printer. Users who enjoy playing games might add a joystick or a trackball; others might connect a modem, scanner, or integrated services digital network (ISDN) terminal to their machines. - - 1 - Input devices An input device is any peripheral (piece of computer hardware equipment) used to provide data and control signals to an information processing system (such as a computer). Input and output devices make up the hardware interface between a computer as a scanner or 6DOF controller. Classification Many 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. keypresses) 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) Pointing devices, which are input devices used to specify a position in space, can further be classified according to: • 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. Touchscreens and light pens involve direct input. Examples involving indirect input include the mouse and trackball. - - 2 - Early devices • Unit record equipment • Punched card Keyboard 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 a linguistic character to a computer, or to call upon a particular function of the computer. Traditional keyboards use spring-based buttons, though newer variations employ virtual keys, or even projected keyboards. Examples of types of keyboards include: • Computer keyboard • Keyer • Chorded keyboard • LPFK A computer mouse - - 3 - Pointing device is any human interface device that allows a user to input spatial data to a computer. In the case of mice and touch screens, this is usually achieved by detecting movement across A a physical surface. Analog devices, such as 3D mice, joysticks, or pointing sticks, function by reporting their angle of deflection. Movements of the pointing device are echoed on the screen by movements of the cursor, creating a simple, intuitive way to navigate a computer's GUI. Composite devices Wii Remote with attached strap Input devices, such as buttons and joysticks, can be combined on a single physical device that could be thought of as a composite device. Many gaming devices have controllers like this. Technically mice are composite devices, as they both track movement and provide buttons for clicking, but composite devices are generally considered to have more than two different forms of input. Imaging and Video input devices Video input devices are used to digitize images or video from the outside world into the computer. The information can be stored in a multitude of formats depending on the user's requirement. • Webcam • Image scanner • Fingerprint scanner • Barcode reader • 3D scanner • Laser rangefinder Audio Input Devices In the fashion of video devices, audio devices are used to either capture or create sound. In some cases, an audio output device can be used as an input device, in order to capture produced sound. • Microphone • MIDI keyboard or other digital musical instrument - - 4 - Output Devices 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 a computer) to the outside world. VDUs Visual Display Units (VDU) or monitors are used to visually interface with the computer and are similar in appearance to a television. A cathode ray monitor A plasma monitor Visual Display Units display images and text which are made up of small blocks of coloured light called pixels. The resolution of the screen improves as the number of pixels is increased. Most monitors have a 4:3 width to height ratio. Ink Jet Printers Characters are formed as a result of electrically charged or heated ink being sprayed in fine jets onto the paper. Individual nozzles in the printing head produce high resolution (up to 400 dots per inch or 400 dpi) dot matrix characters. Colour cartridge showing inkjet nozzles An inkjet printer - - 5 - Inkjet printers use colour cartridges which combine magenta, yellow and cyan inks to create colour tones. A black cartridge is also used for crisp monochrome output. This method of printing can generate up to 200 cps and allows for good quality, cheap colour printing. Robots Robots are able to perform a variety of tasks as a result of executing instructions contained within a program. We are still a long way from the science fiction robots and androids portrayed by the film industry. A robot arm Robots in a business sense mean automated machines designed to perform mundane operations which require accuracy, such as assembling cars. They are seldom manufactured to resemble the human form. Flatbed Plotter This is a plotter where the paper is fixed on a flat surface and pens are moved to draw the image. This plotter can use several different colour pens to draw with. The size of the plot is limited only by the size of the plotter's bed. Top view of a flat bed plotter - - 6 - What Is Hardware The physical, touchable, material parts of a computer or other system. The term is used to distinguish these fixed parts of a system from the more changeable {software} or {data} components which it executes, stores, or carries. Computer hardware typically consists chiefly of electronic devices ({CPU}, {memory}, {display}) with some electromechanical parts (keyboard, {printer}, {disk drives}, {tape drives}, loudspeakers) for input, output, and storage, though completely non-electronic (mechanical, electromechanical, hydraulic, biological) computers have also been conceived of and built. Hardware is the physical aspect of computers, telecommunications, and other devices. The term arose as a way to distinguish the "box" and the electronic circuitry and components of a computer from the program you put in it to make it do things. The program came to be known as the software. Hardware implies permanence and invariability. Software or programming can easily be varied. You can put an entirely new program in the hardware and make it create an entirely new experience for the user. You can, however, change the modular configurations that most computers come with by adding new adapters or cards that extend the computer's capabilities. Like software, hardware is a collective term. Hardware includes not only the computer proper but also the cables, connectors, power supply units, and peripheral devices such as the keyboard, mouse, audio speakers, and printers. Hardware is sometimes used as a term collectively describing the physical aspects of telephony and telecommunications network infrastructure. It is quite well known that the working of the computer is pulled by hardware and software. One can define computer hardware as the electronic, magnetic, and electric devices that carry out the computing functions. Hardware is the physical components of the computer like microprocessor, hard disks, RAM, and motherboard. The peripheral devices such as monitor, mouse, keyboard, printer, and speakers can also be included in the list of hardware parts. The programs that run on the computers like Windows, C++, and Photoshop are the software parts of the computer. A good example for an easy understanding of hardware- software definition is music CDs.

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