1Copyright © Prentice Hall 2000 Input and Output Chapter 4 The User Connection

2Copyright © Prentice Hall 2000 Functions of Computer Systems Recall that there are four main functions of computer systems. InputProcessing Output Secondary Storage

3Copyright © Prentice Hall 2000 Input and Output The computer user is very aware of inputting data and the output (processed information) that is the result.

4Copyright © Prentice Hall 2000 Inputting Data KeyboardKeyboard MouseMouse TrackballTrackball Magnetic-ink character recognitionMagnetic-ink character recognition ScannerScanner Optical mark recognitionOptical mark recognition Optical character recognitionOptical character recognition Bar codesBar codes Handwritten charactersHandwritten characters Voice inputVoice input Touch screensTouch screens LookingLooking

5Copyright © Prentice Hall 2000 Keyboard A keyboard is similar to a typewriter keyboard. Not all keyboards are traditional. Customized keyboards can be found in business, schools, and homes.

6Copyright © Prentice Hall 2000 Mouse The mouse movement corresponds to movement of the pointer (cursor) on the screen. A mouse also has one or more buttons which allow selection of items on a screen.

7Copyright © Prentice Hall 2000 Trackball The trackball stays in one place while the user rolls the ball directly with one hand. Trackballs are ideal when a flat surface does not exist.

8Copyright © Prentice Hall 2000 Magnetic-ink Recognition The most common example of characters made of magnetic particles can be seen on personal checks.

9Copyright © Prentice Hall 2000 Scanner A scanner is an optical recognition system that uses light to scan an image and convert it into electrical signals. The signals are then processed so that the image appears on the computer monitor.

10Copyright © Prentice Hall 2000 Optical Mark Recognition This technique uses a machine to sense marks on a piece of paper. Computer-graded answer sheets rely on optical mark recognition (OMR) to score tests. Exam 1.O O O O 2.O O O O 3.O O O O 4.O O O O 5.O O O O a b c d

11Copyright © Prentice Hall 2000 Optical Character Recognition (OCR) OCR devices use a light source to read special characters or printed text. OCR devices can “read” pages in a book or sale tags on store merchandise.

12Copyright © Prentice Hall 2000 Bar Codes Bar codes appear on the product as a series of zebra-like stripes. Bar codes are used to identify a product when read by a device called a bar code reader.

13Copyright © Prentice Hall 2000 Handwritten Characters Machines can read handwritten characters. However, the size, completeness, and legibility of the handwriting must follow rigid rules. machines that can read

14Copyright © Prentice Hall 2000 Hello Hal. Voice Input Speaking to a computer requires speech recognition devices. The computer processes the sounds into binary code and can “learn” what the code means. Hello Hal.

15Copyright © Prentice Hall 2000 Touch Screens Touch screens are designed so that if touched, the computer knows what the person has selected. Yes NoNo

16Copyright © Prentice Hall 2000 Looking In the future, input might be gathered from our eye movements, and watching images that appear on our retina.

17Copyright © Prentice Hall 2000 Output of Information Useful information for the user can take on a variety of forms: Computer screensComputer screens PrintersPrinters Voice outputVoice output Music and soundMusic and sound

18Copyright © Prentice Hall 2000 Computer Screens Screen output is known as soft copy because it is intangible and temporary. Most computer screens are of the cathode ray variety.

19Copyright © Prentice Hall 2000 Cathode Ray Tube (CRT) Most CRT screens use raster scanning to produce the image. The image must be refreshed often. The rate of refreshing is called scan rate. The image we see actually consists of dots (pixels) on the screen that are either illuminated or not.

20Copyright © Prentice Hall 2000 Pixels Resolution is determined by the number of pixels on the screen. The amount of space between pixels is dot pitch, which determines image quality.

21Copyright © Prentice Hall 2000 Resolution Just Gets Better There are two common resolutions available today: SVGA - 800x x x x1200 XGA- more colors

22Copyright © Prentice Hall 2000 Flat Screens Some computer screens use liquid crystal technology. LCDs are popular with laptop computers.

23Copyright © Prentice Hall 2000 Terminals Terminals integrate a monitor, keyboard and communications link. Smart terminals have their own CPU

24Copyright © Prentice Hall 2000 Printers A printer is an output device that produces a hard copy of your work (a printout on paper). There are two ways to print onto paper: Impact Impact Non-impact Non-impact

25Copyright © Prentice Hall 2000 Impact Printers An impact printer makes physical contact with the paper to produce an image. Impact printers are practical for print jobs in which quantity matters or when multiple (carbon) copies are needed simultaneously.

26Copyright © Prentice Hall 2000 Non-Impact Printers Non-impact printers put the image on the page without physically striking the paper. These printers are best when quality is important.

27Copyright © Prentice Hall 2000 Voice Output Synthesizing speech is much easier for a computer than speech recognition. There are two methods: Synthesis by analysisSynthesis by analysis Synthesis by ruleSynthesis by rule Hello Dave.

28Copyright © Prentice Hall 2000 Synthesis by Analysis In this method of speech synthesis, the output device analyzes the input of a human voice speaking words. The words are stored and the sounds are processed. Later, the computer “talks” by reproducing the words as needed.

29Copyright © Prentice Hall 2000 Synthesis by Rule In this method of speech synthesis, the output device applies a complex set of linguistic rules to create artificial speech.

30Copyright © Prentice Hall 2000 Music and Sound Output May be as simple as attaching speakers to the computer.May be as simple as attaching speakers to the computer. For more serious output, add sound chips to simulate different instruments or sound effects.For more serious output, add sound chips to simulate different instruments or sound effects. Use MIDI to record and playback musical compositions

31Copyright © Prentice Hall 2000 Computer Graphics Output Examples of this kind of output include: Computer art Computer art Science Science Sports Sports Business graphics Business graphics Video graphics Video graphics CAD/CAM CAD/CAM Education Education

32Copyright © Prentice Hall 2000 Business Graphics Business graphics is a powerful way to turn numerical data into more meaningful information. ABCD April Sales by Teams (A, B, C, and D) The addition of color increases understanding.

33Copyright © Prentice Hall 2000 Video Graphics Video graphics combines computer graphics and sound, with the ability to animate a series of frames.

34Copyright © Prentice Hall 2000 TV’s Special Effects Many television programs and movies rely on the special effects made possible with video graphics technology.

35Copyright © Prentice Hall 2000 CAD/CAM Computer-aided design (CAM) and computer-aided manufacturing use computers to design, build, and test products.

36Copyright © Prentice Hall 2000 Digital Cameras Digital cameras take photographs and store them internallyDigital cameras take photographs and store them internally Photos are then sent to the computer for output, or stored on disk.Photos are then sent to the computer for output, or stored on disk.

37Copyright © Prentice Hall 2000 Ethics and Data Just because a computer will allow you to input data and produce new information as output, doesn’t always mean it is legal or right to do so.

38Copyright © Prentice Hall 2000 Ethics and Data Is the situation described below ethical? Use computer software to substitute one person for another in a photograph.

39Copyright © Prentice Hall 2000 Ethics and Data Is the situation described below ethical? Erase contents of s that may help someone filing suit against your company.

40Copyright © Prentice Hall 2000 Conclusion Newer input and output devices are announced regularly. Users reap the benefits of improvements in performance and ease of use.