Hardware Basics:Hardware Basics:

Peripherals

3

2001 Prentice Hall 3.2

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

2001 Prentice Hall 3.3

The Omnipresent Keyboard

Keyboards are used to input and manipulate information with keys such as Letters and Numbers…

2001 Prentice Hall 3.4

The Omnipresent Keyboard

…and Cursor Keys that allow you to move around the screen

…Function Keys that send special commands…

2001 Prentice Hall 3.5

Reading Tools

• Optical-mark readers• Bar-code readers

• Magnetic-ink character readers

• Wand readers

• Pen scanners

2001 Prentice Hall 3.6

Scanners

Digitizing the Real World

Audio digitizing andSpeech recognition software

Video digitizing

Sensing devices

2001 Prentice Hall 3.7

Scanners

Scanners capture and digitize images from external paper sources

2001 Prentice Hall 3.8

Video Digitizers

Video digitizers contain circuitry to digitize frames from camcorders and other video sources.

2001 Prentice Hall 3.9

Digital Cameras

Digital cameras turn real-world scenes into digital images that can be stored and manipulated by the computer

The images, stored in memory, can be transferred to a computer for either editing or storage

2001 Prentice Hall 3.10

Audio Digitizers

• Audio digitizers contain circuitry to digitize sounds from microphones and other audio devices.

• Spoken words, music, and sound effects can be captured.

2001 Prentice Hall 3.11

Sound

Video Monitor

ControllingOther Machines

Output: From Pulses to People

Paper

2001 Prentice Hall 3.12

Screen Output

• Video Monitor

– Also called Video Display Terminal (VDT)

– Image exists in video memory—VRAM

– Monitor size is measured diagonally across the screen

2001 Prentice Hall 3.13

• Images are made up ofdots called pixels forpicture elements

Pixels

• The number of pixelsaffects the resolutionof the monitor

• The higher the resolution,the better the image quality

2001 Prentice Hall 3.14

Color Depth (Pixel Depth)

• The amount of information per pixel is known as the color depth

– Monochrome (1 bit of information per pixel)

– Gray-scale (8 bits of information per pixel)

– Color (8 or 16 bits of information per pixel)

– True color (24 or 32 bits of information per pixel)

2001 Prentice Hall 3.15

Examples of Color Depth

1-bit depth

16-bit depth8-bit depth

4-bit depth

2001 Prentice Hall 3.16

CRT (cathode ray tube)

LCD (liquid crystal display)

Classes of Monitors

2001 Prentice Hall 3.17

A CRT is a television-style monitorfeaturing:

CRT (Cathode Ray Tube)

– Clear image

– Quick response time

– Low cost

2001 Prentice Hall 3.18

• LCDs are flat-panel monitors

• Features include:– Lighter weight

– More compact

• More expensive

• Dominate the portable computer market

LCD (Liquid Crystal Display)

2001 Prentice Hall 3.19

Paper Output

• Paper output is sometimes called hard copy

• Hard copy can come from one of two kinds of printers:

– Impact printers

– Nonimpact printers

2001 Prentice Hall 3.20

• Line printers– Used by mainframes for

massive jobs

– Limited characters available

Impact Printers

• Dot-matrix printers– Image formed from dots printed on paper

– Good for text and graphics

– Inexpensive

2001 Prentice Hall 3.21

Nonimpact Printers

• Laser printers

– Image transferred to paper with laser beam

– Faster and more expensivethan dot-matrix

– High-resolution hard copy

2001 Prentice Hall 3.22

Other Nonimpact Printers

• Ink-jet

– Dots of ink are sprayed onto the paper to form the image

– High-resolution hard copy

– Some models print can print colorphotographs

2001 Prentice Hall 3.23

Rules of Thumb:Ergonomics and Health

• Choose equipment that’s ergonomically designed

• Create a healthy workspace

• Build flexibility into your work environment

• Rest your eyes

• Stretch tight muscles

2001 Prentice Hall 3.24

Output You Can Hear

• Synthesizers can beused to generate music and sounds

• Many computershave synthesizers

• Sound cards havebuilt-in synthesizers

2001 Prentice Hall 3.25

• Output devices turn bit patterns into non-digital movements

Controlling Other Machines

— Robot arms— Telephone switchboards— Transportation devices— Automated factory

equipment— Spacecraft

2001 Prentice Hall 3.26

Storage Devices:Input Meets Output

• Peripherals with both input and output functions provide semi-permanent storage for data

• Examples include:

– Magnetic tape and disks

– Zip, Jaz and SuperDisks

– Magneto-optical disks

2001 Prentice Hall 3.27

Optical Disks

• Optical disks use laser beams rather than magnets to read and write information

• CD-RW drives can write, erase, and rewrite CDs

• CD-ROM drives are optical drives that read CD-ROMs

• DVD’s can hold between 3.8 and 17 gigabytes of data, they are replacing CD-ROMs

2001 Prentice Hall 3.28

Alternatives

• Flash memory

– Compact alternative

– No moving parts

– May eventually replace disk and tape storage

2001 Prentice Hall 3.29

Ports and Slots…again

• The system board (motherboard) includes several ports:– Serial Port for attaching devices that

send/receive messages one bit at a time (modems)

– Parallel Port for attaching devices that send/receive bits in groups (printers)

– Keyboard/Mouse Port

2001 Prentice Hall 3.30

Ports and Slots…again

• Other ports that are generally included on expansion boards instead of the system board:

– Video Port used to plug in a color monitor into the video board

– Microphone, speaker, headphone, MIDI ports used to attach sound equipment

– SCSI port allows several peripherals to be strung together and attached to a single port

2001 Prentice Hall 3.31

Internal and External Drives

• Hard drive

• CD or DVD

• Floppy disk

• Zip Drive

• SCSI port

2001 Prentice Hall 3.32

Expansion Made Easy

• USB and Firewire ports allow multiple devices to be connected to the same port and to be hot swapped:

– 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

2001 Prentice Hall 3.33

Putting It All Together:Networks

• Networks blur the boundaries between computers

– Networks can include hundreds of different computers

– Can span the globe by using satellites and fiber optic cables