CS10001 Class Note: Chapter 3Hardware Basics: Peripherals
Objectives

List several examples of input devices and explain how they can make it easier to get different types of information into the computer
 List several examples of output devices and then explain how they make computers more useful

Explain why a typical computer has different types of storage devices

Diagram how the components of a computer system fit together
Bill Gates Rides the Digital Wave

Formed Microsoft with Paul Allen

Targeted software for personal computers

Operating Systems: MS-DOS, Windows

MS Office and Internet Explorer
Input: From Person to Processor
 Keyboard

The most familiar input device

QWERTY

Used to enter letters, numbers, and special characters

Types of keyboards

Standard keyboard

Ergonomic keyboards o To address possible medical problems

Wireless keyboard

Folding keyboards o Used with palm-sized computers

One-handed keyboards

Keyboards printed on membranes

Pointing Devices

Mouse

Touchpad
 Pointing stick

Trackball

Joystick

Graphics tablet

Touch screen

Stylus

Reading Tools
 Read marks representing codes specifically designed for computer input

Optical-mark readers

Magnetic-ink character readers
 Bar-code readers

Pen scanners

Tablet PC

Smart whiteboard

RFID (Radio Frequency Identification Readers)


Digitizing the Real World

Scanners capture and digitize printed images.

Flatbed

Slide

Drum

Sheet fed

Digital camera

Snapshots captured as digital images

Digital images stored as bit patterns on disks or other digital storage media
 Video digitizer

Capture input from a:

Video camera

Video cassette recorder or television

Convert it to a digital signal

Stored in memory and displayed on computer screens
 Videoconferencing

People in diverse locations can see and hear each other

Used to conduct long-distance meetings

Video images transmitted through networks

Audio digitizers

Digitize sounds from

Microphones

Other input devices

Digital signals can be

Stored

Further processed with specialized software

A digital signal processing chip compresses the stream of bits before it is transmitted to the CPU.

Speech recognition software

Converts voice data into words that can be edited and printed
 Sensors

Designed to monitor physical conditions

Temperature, humidity, pressure

Provide data used in:

Robotics

Environmental climate control

Weather forecasting

Medical monitoring

Biofeedback

Scientific research
Output: From Pulses to People

Screen Output

Monitor size: Measured as a diagonal line across the screen

Resolution: The number of pixels displayed on the screen

Pixels (or picture elements): tiny dots that compose a picture


The higher the resolution, the closer together the dots

Image quality affected by resolution and color depth (bit depth).

Color depth refers to the number of different colors a monitor displays at one time

Screen Output

Monitor classes

CRTs (cathode-ray tubes)

LCDs (liquid crystal displays) o Overhead projection panels o Video projectors o Portable computers

Screen Output

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 picture detail is displayed.

Paper Output

Printers produce paper output or hard copy.

Two basic groups of printers:

Impact printers o Line printers o Dot-matrix printers

Nonimpact printers

Laser printers o Laser beam reflected off a rotating drum to create patterns of electrical charges o Faster and more expensive than dot-matrix printer o High-resolution output
 MFP (Multifunction printer), or all-in-one device, combines a scanner, printer, and a fax modem.

A plotter can produce large, finely scaled engineering blueprints and maps.

Fax Machines and Fax Modems

Fax (Facsimile) machine

Sending: o Scans each page as an image o Converts the image into a series of electronic pulses o Sends those signals over phone lines to another fax

Receiving: o Uses the signals to reconstruct the image o Prints black-and-white facsimiles or copies of the originals
 Fax modem

Connect from PC to fax machine via modem and phone line

Translates a document into signals

Output You Can Hear

Sound card

Enables the PC to: o Accept microphone input o Play music and other sound through speakers or headphones

o Process sound in a variety of ways

Synthesizers

Used to produce music, noise

Controlling Other Machines

Output devices take bit patterns and turns them into nondigital movements.

Robot arms

Telephone switchboards

Transportation devices

Automated factory equipment

Spacecraft

Force feedback joystick

Rules of Thumb:
Ergonomics and Health
 Choose equipment that’s ergonomically designed.

Create a healthful workspace.
 Build flexibility into your work environment.

Rest your eyes.

Stretch.

Listen to your body.

Seek help when you need it.
Storage Devices: Input Meets Output

Magnetic Tape

Can store large amounts of information in a small space at a relatively low cost

Limitation: sequential data access

Used mainly for backup purposes

Magnetic Disks

Random access capability

Floppy disks (1.44 MB)

Provide inexpensive, portable storage

Hard disks

Nonremovable, rigid disks that spin continuously and rapidly

Provide much faster access than a floppy disk

Optical Disks

Use laser beams to read and write bits of information on the disk surface

Not as fast as magnetic hard disks

Massive storage capacity

Very reliable

CD–ROM

Optical drives that read CD–ROMs

Holds 700 MB of information

CD–R

WORM media (write-once, read many)

CD–RW

Can read CD–ROMs and write, erase, and rewrite data onto CD–R and CD–RW disks

DVD (digital versatile disks)


Store and distribute all kinds of data

Hold between 4.7 and 17 GB of information

DVD–ROM drives

Can play DVD movies, read DVD data disks

Read standard CD–ROMs and play audio CDs

Read-only: can’t record data, music, or movies

DVD–RAM drives

Can read, erase, and write data (but not DVD video) on multi-GB DVD–R (but not
CD–R or CD–RW) media

BD drives (Blu–ray)

Hold up to 50 GB of information on two layers

Enough for a full-length HD movie

BD–R

Can read Blu-ray discs, DVDs, and CDs

BD–RW drives

Can read and record on Blu-ray discs, DVDs, and CDs

Internal and External Drives

Internal drives

Reside in bays inside the system unit

External drives

Connected by USB or Firewire ports

Contained in their own case

May be compatible with more than one OS

Flash Memory Storage Devices

An erasable memory chip

Compact alternative to disk storage

Contains no moving parts

Designed for specific applications such as storing pictures in digital cameras

Likely to replace disk and tape storage

Large capacity, over 1 GB

Portable

SD (secure digital) cards, CF (compact flash), and memory sticks
 USB flash drives, also thumb or jump drives
Computer Systems: The Sum of Its Parts

Personal Computer Design Classes

Tower systems

Tall, narrow boxes, generally have more expansion slots and bays than other designs

Flat desktop systems

Designed to sit under the monitor like a platform

All-in-one systems (like the iMac)

Combine monitor and system unit into single housing
 Laptop computers

Include all the essential components, including keyboard and pointing device, in one compact box


Ports and Slots Revisited

Legacy ports–outdated due to slow speeds:

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 for attaching a keyboard and a mouse

Other ports are typically included on expansion boards rather than the system board:

A video port is used to plug a color monitor into the video board.

Microphones, speakers, headphones, MIDI ports are used to attach sound equipment.

An SCSI port allows several peripherals to be strung together and attached to a single port.

A LAN port uses faster connections to a LAN (local area network).

With the PC open architecture and the introduction of new interfaces, you can hot swap devices.

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 MB per second.
The high speed makes it ideal for data-intensive work, like digital video.

FireWire 800, which offers 800 Mbps transfer speeds, was recently introduced on highend Macintosh systems.

SATA (Serial-ATA or Serial Advanced Technology Attachment)

Used to connect internal hard drives and optical drives

Can transfer data up to 1200 Mbps
Inventing the Future: Tomorrow’s Peripherals
 Tomorrow’s Storage

Smaller disks that hold more

A single electron memory chip the size of a thumbnail that can store all of the sounds and images of a full-length feature film
 Tomorrow’s Output

Goggles that block out everything around you
 Retinal displays that work without a screen
 Tomorrow’s Input: Sensors

More sophisticated devices will serve as the eyes, ears, and other types of sense organs for computer networks.
Lesson Summary

Peripherals allow computers to communicate with the outside world and store information for later use.

The most common input devices today are the keyboard and the mouse. A variety of other input devices can be connected to the computer.

Output devices perform the opposite function: They accept strings of bits from the computer and transform them into a form that is useful or meaningful outside the computer.

Storage devices are capable of two-way communication with the computer. Because of their high-speed random access capability, magnetic disks are the most common forms of storage on modern computers.