Comprehensive Overview of Computer Input and Output Devices

1. Chapter 4 Input and Output

2. Overview • This chapter covers: • Keyboards and pointing devices • Scanners and related devices • Biometric and multimedia input devices • Various types of display devices • Various types of printers • Multimedia output devices

3. Input and Output • Input devices convert data from the user into a form understood by the computer. • Output devices convert the processed 0s and 1s into a form that the user can understand. • Hard copy—permanently recorded, such as on paper. • Soft copy—temporarily recorded, such as on a computer screen.

4. Keyboards • Computers usually use a keyboard for text-based input. • Keyboards can differ in number of keys, key arrangement, types of special keys, and touch. • Function keys enable software packages to be customized to meet a user's applications needs. • The numeric keypad makes it easy to enter numbers quickly.

6. Keyboards, Cont’d. • Portablekeyboardsand thumb pads are increasingly being used with portable PCs and mobile devices.

7. Pointing Devices • Mice • The mouse is the most common type of pointing device. • Can be mechanical or optical. • Used to select onscreen objects, issue commands, move objects, scroll through documents, etc.

9. Pointing Devices, Cont’d. • Electronic pens (light pen, stylus) • An alternative to the mouse to select objects or to write or draw on the screen. • Commonly used with: • Graphics tablets • Digital portfolios and digital pens • Signature capture devices • Pen-based computers • Handwriting recognition technology

11. Pointing Devices, Cont’d. • Touch screens • Used when other input devices are impractical. • Often used when consumer input is required, as in consumer kiosks.

12. Pointing Devices, Cont’d. • Other common pointing devices • Joysticks and other gaming devices • Trackballs • Pointing sticks • Touch pads

13. Scanners and Related Devices • Source data automation involves converting source documents to digital form or initially collecting data in digital form. • Often involves scanning or readingdevices.

14. Scanners • Scanners (optical scanners) convert hard-copy images of text pages, photographs, and drawings into digital form. • Types of scanners: • Flatbed • Sheet-fed • Handheld • Drum • Three-dimensional • Quality of scanned images are measured by resolution.

16. Optical Mark Readers (OMRs) • Read opticalmarks, such as on: • Exams • Census forms • Voting ballots • Lottery forms

17. Bar-Code Readers • Bar code—an optical code consisting of several bars of varying widths that form a unique, identifiable code. • Read by fixed or portable bar-code readers. • Common types: • Universal Product Code (UPC) • POSTNET code • Proprietary codes for shippers, hospitals, and other businesses

18. Optical Character Recognition (OCR) Devices • Optical characters are designed to be identifiable by humans as well as OCR device. • Widely used in turnaround documents, such as monthly bills.

19. Magnetic Ink Character Recognition (MICR) Readers • MICR readers can read the special magnetic characters and sort and processdocuments accordingly. • Used primarily for processing checks.

20. Biometric Input Devices • Used to input biometric data about a person. • Biometric data is based on unique physical characteristics (e.g. fingerprint) or personal traits (e.g. voice). • Used for access and to verify transactions. • Biometric readers can be stand-alone or built into keyboards or other hardware devices.

21. Multimedia Input Devices • Digital cameras record data onto digital media instead of conventional film or tape. • Images can be transferred to a PC via a cable or the storage media (such as a flash memory card with a digital still camera). • Can be digital still cameras or digital video cameras.

22. Multimedia Input Devices, Cont’d. • Digital still cameras • Images are usually stored on flash memory cards. • Photos can usually be immediately previewed and deleted, if needed. • Photos are easily transferred to a PC to be stored and/or printed. • Camera quality is measured in mexapixels. • Digital photos can be printed at home or at a photo lab.

24. Multimedia Input Devices, Cont’d. • Digital video cameras • Store images on digital media (typically digital tape or optical discs). • Video can be easily transferred to a PC for editing and/or burning onto a DVD. • Can be used for videoconferencing and Web cams.

25. Multimedia Input Devices, Cont’d. • Audio input devices • Voice-input systemsconvert spoken words to digital data. • Voice input can be used to input data or commands into a PC as well as for telephony. • Music-input systems can input and record music (either original compositions or via a CD or DVD player).

26. Display Devices • Display device characteristics • Color vs. monochrome displays • Size (measured diagonally) • Screen resolution • Graphic standards

27. Display Devices, Cont’d. CRT (cathode-ray tube) monitors—display images similar to conventional televisions. Quality is measured in dot pitch.

28. Display Devices, Cont’d. Flat-panel displays—form images by manipulating electronically-charged chemicals or gases between thin panes or glass or plastic. Common types: Liquid crystal displays (LCD) Gas plasma Used for monitors, televisions, handheld devices, and other consumer products.

30. Display Devices, Cont’d. • Smart displays • HDTV monitors • Data projectors • Emerging display technologies and applications (e.g. flexible displays, e-paper, integrated displays, etc.)

31. Printers • Printer characteristics • Printer resolution—measured in dots per inch (dpi) • Impact vs. non-impact printing • Color vs. black and white • Personal vs. network printers • Speed

32. Laser Printers • The standard for business documents. • Work similarly to photocopy machines; print with toner powder. • Are usually black and white, though color laser printers are available. • Fast print speed; print one page at a time.

33. Ink-Jet Printers • Print with tiny drops of liquid ink. • Typically print in color. • Often the choice for home use. • Print fairly slowly, one line at a time. • Quality not quite as good as a laser printer.

34. Special Purpose Printers • Photo printers • Bar-code printers • Label printers • Portable printers • Plotters and wide-format ink-jet printers • Fax machines • Multifunction devices • 3D Printers

36. Multimedia Output Devices • Speakers • Voice-output systems- sometimes called text-to-speech systems • Headphones and Headset