Chapter 3

1. Chapter 3 Hardware Basics: Peripherals

2. Chapter Outline • Input: From Person to Processor • Output: From Pulses to People • Storage Devices: Input meets Output • Computer Systems: The Sum of Its Parts “We swim in a sea of information.” Gary Snyder, poet

3. Input: From Person to Processor

4. The Keyboard The most common input device is the keyboard, which is used to enter letters, numbers and special characters.

5. Working with the Keyboard • Function keysare special purpose keys whose function depends on the software being used. • Cursor keysare used to move the cursor up, down, left, or right.

6. Variations on Keyboard Design • Ergonomic • to address repetitive stress injuries • Wireless • Folding • Half • Vertical • Chording

7. QWERTY vs. Dvorak

8. Pointing Devices

9. Pointing Devices Head Controlled Mouse Sip and Puff Mouse

10. Reading Tools Input devices “read” directly from paper and convert printed information into bit patterns that can be processed by the computer. • Optical-mark readers • Bar-code readers • Magnetic-ink character readers • Wand readers • Pen scanners

11. Digitizing the Real World • Scanner • Digital camera • Speech recognition • Sensing devices • Audio and video digitizers

12. Scanners • Scanners capture and digitize printed images. There are several types of scanners: • Flatbed scanners • Handheld scanners • Sheet-fed scanners

13. Digital Cameras Digital cameras capture snapshots and store them as bit patterns on disks or other storage media.

14. Video Digitizers Video digitizers capture input from video sources such as video camera and convert it to a digital signal that can be stored in memory and displayed on a computer screen.

15. Audio Digitizers • Audio digitizers capture spoken words, music and sound effects and convert them to digitized sounds. • These sounds can be stored in a computer’s memory and modified with computer software.

16. Sensing Devices • Sensing devices are used to monitor temperature, humidity, pressure and other physical quantities. • The data collected provides data for use in robotics, environmental climate control, weather forecasting and other applications.

17. Output: From Pulses to People • Screen Output • Paper Output • Sound Output • Controlling Other Machines

18. Screen Output • A monitor or video display terminal (VDT) displays characters, graphics, photographic images, animation and video. • Video adapter—connects the monitor to the computer • VRAM or video memory—a special portion of RAM to hold video images (the more video memory, the more detail of a picture displayed)

19. Screen Talk • Monitor size - measured as a diagonal line across the screen. • Pixels (or picture element) - tiny dots that compose a picture • Resolution- the number of pixels displayed on the screen (the higher the resolution, the closer together the dots)

20. Image Quality • Image quality is affected by resolution and color depth (or bit depth) • Color depth refers to the number of different colors a monitor displays at the same time

21. 4-bit depth 1-bit depth 8-bit depth 16-bit depth Examples of Color Depth

22. Monitor Classes CRT (cathode ray tube) LCD (liquid crystal display)

23. Cathode Ray Tube (CRT) • The cathode ray tube has the following characteristics: • Low cost • Speedy response time • Clear image

24. Liquid Crystal Display (LCD) • Light-weight • Compact • Flat-panel • Used in overhead projection panels and video projectors to project computer images • More expensive than CRTs • Increasingly being seen with desktop computers

25. Paper Output • Printers produce paper output or hard copy • 2 kinds of printers: • Impact printers • Non-impact printers

26. Impact Printers • Line printer • Used by mainframes to produce massive printouts • Limited to printing characters • Dot matrix printer • Images created by a matrix of tiny dots • Low print quality • Low cost

27. Non-impact Printers • A laser beam reflected off a rotating drum to create patterns of electrical charges • Faster and more expensive than dot matrix printer • High-resolution output Laser Printer

28. More on Non-impact Printers • Sprays ink onto paper to produce printed text and graphic images • Prints fewer pages/minute than laser printer • High-quality color costing less than laser printer Ink-jet Printer

29. Additional Output Devices • Multifunction peripheral or MFP combines a scanner, printer and a fax modem. • A plotter is an automated drawing tool that can produce large, finely scaled engineering blueprints and maps.

30. Output You Can Hear • Asound card allows the PC to accept microphone input, play music and other sounds through speakers or headphones. • Synthesizersare included in sound cards and have specialized circuitry designed to generate sounds electronically.

31. Controlling Other Machines • Robot arms • Telephone switchboards • Transportation devices • Automated factory equipment • Spacecraft • Digiscents Output devices take bit patterns and turn them into non-digital movements.

32. Rules of Thumb: Ergonomics & Health • Choose equipment that’s ergonomically designed • Create a healthy workspace • Build flexibility into your work environment • Rest your eyes • Stretch to loosen tight muscles • Listen to your body

33. Storage Devices: Input Meets Output • Secondary storage devices are computer peripherals capable of performing both input and output functions • Information is stored semi-permanently on tape and disk drives • Examples of storage devices • Magnetic tapes and disks • Zip, Jaz and SuperDisks • Optical disks

34. Magnetic Media • Magnetic tapes • Sequential access • Can store large amounts of information in a small space at a relatively low cost • Limitation: sequential access • Used mainly for backup purposes

35. Magnetic Media • Magnetic drives • Random access • Floppy disks for inexpensive, portable storage • Hard disks are non-removable, rigid disks that spin continuously and rapidly thus providing much faster access than a floppy disk. • Removable media (Zip & Jaz disks) provide high-capacity portable storage.

36. Optical Media • Not as fast as magnetic hard disks • Massive storage capacity and reliability Optical disk drive uses laser beams to read and write bits of information on the disk surface.

37. Types of Optical Media • CD-ROM drives are optical drives that read CD-ROMs. • CD-R are WORM media (write-once, read many). • CD-RW can read CD-ROMs and write, erase and rewrite data onto CD-R & CD-RW disks. • DVD (digital versatile disks) store & distribute all kinds of data. They hold between 3.8 and 17 gigabytes of information.

38. Solid-state Storage Devices • Compact alternative • No moving parts • Designed for specific applications such as storing pictures in digital cameras • Likely to replace disk and tape storage Flash memory is an erasable memory chip.

39. Ports and Slots Revisited • The system or motherboard includes several standard ports: • Serial Portfor attaching devices that send/receive messages one bit at a time (modems) • Parallel Portfor attaching devices that send/receive bits in groups (printers) • Keyboard/Mouse Portfor attaching a keyboard and a mouse

40. More on Ports and Slots • Other ports are typically included on expansion boards rather than the system board: • Video Portused to plug in a color monitor into the video board • Microphone, speaker, headphone, MIDI portsused to attach sound equipment • SCSI port allows several peripherals to be strung together and attached to a single port

41. Expansion Made Easy • USB (Universal Serial Bus) transmits a hundred times faster than a PC serial port • Firewire (IEEE 1394) can move data between devices at 400 or more megabits per second • high speed makes it ideal for data-intensive work like digital video With the open architecture of the PC and the introduction of new interfaces, you can hot swap devices.