1unit two input output
- 2. 2 CONTENTS • Introduction • Input Devices – Keyboard,mouse,joystick,scanners,digital camera, bar code reader, touch Sreeen,Speech input device (microphone) • Output Devices – Monitor , Speaker, Printers ( different types)
- 4. 4 What’s available for input… • touch - fingers, feet, breath • sound - voice, other sounds • gesture • gaze • brainwaves…
- 5. 5 and output… • textual information • visual images - photos, diagrams, icons • moving images • sounds - music, voice • Etc..
- 6. 6 2.Input Devices •Used by a person to communicate to a computer. Person to computer Input Devices video
- 7. 7 Output Devices •Displays information from the computer to a person. Output Devices video
- 8. 8 Input Devices • Keyboard. • Mouse • Microphone • Digital Camera • Scanner • Video
- 9. 9 The Keyboard The most commonly used input device is the keyboard on which data is entered by manually keying in or typing certain keys. A keyboard typically has 101 or 105 keys.
- 10. 10 Keyboard • The keyboard allows the computer user to enter words, numbers, punctuation, symbols, and special function commands into the computer’s memory.
- 11. 11 The Mouse Is a pointing device which is used to control the movement of a mouse pointer on the screen to make selections from the screen. A mouse has one to five buttons. The bottom of the mouse is flat and contains a mechanism that detects movement of the mouse.
- 12. 14 Pointing devices - direct • Touch screens
- 13. 15 Touch screens • Often used for applications with occasional use, for example • Bank ATMs, Information Kiosks, etc. • No extra hardware - used for input and for output • Can be precise to 1 pixel • Good for menu choice - not so good for other functions • Intuitive to use
- 14. 16 Touch screens • BUT • Tiring if at wrong angle (needs to be 30-45% from horizontal) • Get greasy, jammy • Finger can obscure screen • Alternative - use stylus to touch screen, or lightpen
- 15. 17 Indirect Pointing Devices • Need more cognitive processing than direct methods, but can be more efficient • mouse • tracker ball • track point • touchpad…
- 16. 18 Indirect pointing devices - other • Tracker ball, trackpad, trackpoint • Less space on desktop • Good in moving environments, e.g. car, train
- 17. 19 Indirect pointing devices - other • Joystick • The main use of a joystick is to play computer games by controlling the way that something moves on the screen.
- 18. 20 Microphones - Speech Recognition •Use a microphone to talk to your computer •Add a sound card to your computer •Sound card digitizes audio input into 0/1s •A speech recognition program can process the input and convert it into machine-recognized commands or input
- 19. 21 Audio Input: Speech Recognition • Speech recognition is a type of input in which the computer recognizes words spoken into a microphone. • Special software and a microphone are required. • Latest technology uses continuous speech recognition where the user does not have to pause between words.
- 20. 22 Microphones - Speech Recognition
- 21. 23 Digital camera A digital camera can store many more pictures than an ordinary camera. Pictures taken using a digital camera are stored inside its memory and can be transferred to a computer by connecting the camera to it. A digital camera takes pictures by converting the light passing through the lens at the front into a digital image.
- 22. 24 Scanner A scanner can be used to input pictures and text into a computer. There are two main types of scanner; Hand-held and Flat-bed.
- 23. 25 Light pen •A light pen is a small ‘pen-shaped’ wand, which contains light sensors. •It is used to choose objects or commands on the screen either by pressing it against the surface of the screen or by pressing a small switch on its side. •A signal is sent to the computer, which then works out the light pen’s exact location on the screen. •The advantage of a light pen is that it doesn’t need a special screen or screen coating.
- 24. 26 Bar codes •A bar code is a set of lines of different thicknesses that represent a number •Bar Code Readers are used to input data from bar codes. Most products in shops have bar codes on them •Bar code readers work by shining a beam of light on the lines that make up the bar code and detecting the amount of light that is reflected back
- 25. 28 2. Output Types • Text output • Graphics output • Video output • Audio output
- 26. 29 Output Devices: Engaging our Senses • Output devices are peripheral devices that enable us to view or hear the computer’s processed data. – Visual output – Text, graphics, and video – Audio output – Sounds, music, and synthesized speech
- 27. 30 Output Devices • Monitors • Printers • Speakers • Data Projectors
- 28. 31 Monitors • A monitor is a peripheral device which displays computer output on a screen. • Screen output is referred to as soft copy. • Types of monitors: – Cathode-ray tube (CRT) – Liquid Crystal Display (LCD or flat-panel) CRT LCD
- 29. 32 Monitors • CRT – cathode ray tube • electron gun shoots a stream of electrons at a specially phosphor-coated screen • on impact, the phosphor flares up for a fraction of a second • electron gun sweeps across the screen many times a second • LCD – liquid crystal display • one of several types of “flat-panel” displays • forms output by solidifying crystals and “backlighting” the image with a light source – TV sets are CRTs and many desktop monitors use this technology – LCD is primarily used for laptops and other portable devices
- 30. 33 Video Display Terminology • Pixel – picture element (smallest unit of an image, basically a single dot on the screen) • Resolution – number of pixels in the image – Common resolution size is 1024x768 – Refresh rate • how often a CRT’s electron gun rescans • LCD displays do not use an electron gun, so do not perform refreshing The CRT electron gun “shoots” 3 electrons at the screen representing the amount of red, green and blue for the pixel
- 31. 34 Printers • Ink Jet Printer – least expensive, color, slower with a higher per page cost than laser printers • Laser Printer – More expensive, faster, lower per page cost than ink jet,
- 32. 35 Printers • A printer is a peripheral device that produces a physical copy or hard copy of the computer’s output.
- 33. 36 Inkjet Laser Types of Printers • Inkjet printer, also called a bubble-jet, makes characters by inserting dots of ink onto paper • Letter-quality printouts • Cost of printer is inexpensive but ink is costly • Laser printer works like a copier • Quality determined by dots per inch (dpi) produced • Color printers available • Expensive initial costs but cheaper to operate per page
- 34. 37 Plotter • A plotter is a printer that uses a pen that moves over a large revolving sheet of paper. • It is used in engineering, drafting, map making, and seismology.
- 35. 38 Audio Output: Sound Cards and Speakers • Audio output is the ability of the computer to output sound. • Two components are needed: – Sound card – Plays contents of digitized recordings – Speakers – Attach to sound card
- 36. 39 Questions 1.Enlist and Explain Input Devices. 2.Enlist and Explain Output Devices.