Peripheral device is a device that are connected to the computer. Scanner, printer,mouse,keyboard, microphone,tape device and external modem are some of them. Internal devices include external modem ,Zip drive , printer and many others. Peripheral devices can be divided into input,output and storage.Input devices are the type of computer device who we can control the signal in the computer. Mouse and keyboards are the examples of the input devices.Output devices are the devices that are used to displaying us sounds,pictures,videos and so on. Speaker,printer,scanner and the monitor are the examples of the output devices.Storage device is a device that is used to keep files,informations and many other things.Storage device include flash drive, hard disk drive, tape drive and the floppy disk.
Input devices includes keyboards,pointing devices ,composite devices,imaging video input devices and audio input devices.First of all is keyboard.In the computing world,a keyboard is a typewriter keyboard, which is design with an arrangement of keys,they are to act as mechanical pry bars or electronic switches. Punch cards and paper tape have declined nowadays, interaction through type-style keyboards turn into the primary input device for computers.Although the growth of alternative input devices,the keyboard are still the most commonly used and most important device used for input into computers.A keyboard usually has characters stamped on the keys and each press of a key usually corresponds to only a single written symbol. However, to produce some symbols requires pressing or holding several keys at the same time or in sequence.Almost all keyboard keys produce with alphabets, numbers or signs, other keys or simultaneous key presses can get some actions or computer instructions.In normal usage, the keyboard is used to type numbers and texts into a word processor, text editor or any other programs. In a modern day computer, the interpretation of key presses is commonly left to the software itself. A computer keyboard differentiate 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 unique gaming features, which can expedite often used buttons combinations. A keyboard is also used to give orders to the operating system of a computer.Thats why keyboard is really important to computers.Secondly,is the pointing device,traditionally,computers were controlled by typing in commands at the keyboard.However,as far back as the mid-1960s researchers had begun to experiment with providing users with more natural ways to interact with the machine.In 1965,a guy names Douglas Engelbart at the Stanford Research Institute(SRI) devised a small box that moved over the desk on wheels and was connected to the computer by a cable.As the user moved the box around,it sent signals representing its motion.These signals in turn were used to draw a pointer on the screen was less taxing on users than alternative such as light pens or joysticks.This device,dubbed a"mouse",remained largely a laboratory novelty.In the 1970s,however ,xerox designed a mouse-driven graphical user interface for its Alto system,which saw only limited use.In 1984,however,Apple introduced the mouse to millions of users were switching their IBM-compatible PCs from text commands to the mouse-driven Windows interface.Today a dekstop PC without a mouse would be as inthinkable as one without a keyboard.Meanwhile,the mouse became smaller and sleeker.Instead of wheels,the contemporary mouse uses a rolling ball that turns two adjacent rollers inside the mouse.A mouse pad with a special surface is generally used to provide uniform traction.A new type of mouse uses optical sensors instead of rollers to sense its changing position.Since mice are generally impracticable for laptop use,designers have offered a variety of alternatuves.These include a trackball,a touch-sensitive finger pad,or a small stub that can be moved like joystick by the fingertip.Most mice now have at least two buttons.Generally,the left button is used for selecting objects,opening menus,or launching programs.The right button is used to bring up a menu of actions that can bedone with the selected object.Activating a button is called clicking.It is the operating system that assigns significance to clicking or double-clicking or dragging.Some mice have a third button or a small wheel that can be used to scroll the display,but only certain software recognizes these functions.
The third one is composite devices. Input devices, like buttons and joysticks, can be combined on a single device that could be considered as a composite device. Many gaming devices have this kind of controllers. Technically mouse are composite devices,they are two who both track movement and offer buttons for clicking, however composite devices are commonly considered to have forms more than two different forms of input.Game controller is one of them.A game controller is a device used to play games or entertainment systems. They are designed to manage or control a character or object such as peoples,cars,planes,cartoon characters or even a ball and many others. A controller is usually connected to the computer or game console with a wire,or in these days,there are also wireless connection available. Controllers which have been categorized as game controllers are joysticks,game pads, mice, keyboard and many others. Special aimed devices,like steering wheels for motorsport racing games and light guns for shooting or war games, are also considered as game controllers. Devices like mice and keyboards can be simulated along with a game pad through the functions of programs. The most important function of a game controller is to control the actions or movements of a object or else it will affect the events in a computer or video game.The kinds of controllers being used in a game based of the game being played.
Output devices include speaker,printer,monitor.First of all is speaker, speakers can be classified to computer speakers, or multimedia speakers.They are external to a computer, that stops the lower fidelity built-in speaker. They usually will have a low-powered internal amplifier. The ordinary audio connection is a 3.5 mm just about 1/8 inch stereo jack plug often will be colored or coded lime green by following the PC's standard.The cable that is generally used to connect analog audio and video components.A rows of RCA sockets are seen on the backs of the stereo amplifier and several A/V products. There are also USB speakers nowadays available in the market.They are really popular and welcomed by the users.Computer speakers is widely been selected based on the quality and the price. The computer speakers usually packaged together with computer systems.Speakers are small,made of plastic, and have mediocre sound quality.But some computer speakers have equalization features like bass or treble controls.More complicated computer speakers will have a subwoofer unit, to develop bass output, and these units typically include power amplifiers for both the small satellite speakers and the bass speaker.There are also some computer who have rather basic speakers built-in.Laptops come with built-in speakers. Limited space available in laptops means that these speakers usually produce unimpress quality sound.
For some users, a lead connecting computer sound output to an currently existing stereo system is realistic. This usually produce much improved results than small low-cost computer speakers. Computer speakers can also serve up as an economy amplifier for MP3 player use for those people who not fancy by using headphones while some models of computer speakers does exists headphone jacks on their own.
