01B - Input Output Devices and Hardware

7/31/2019 01B - Input Output Devices and Hardware

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Input Output Devices


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Back of Computer

Remove these screws


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Step 2 Looking Inside

Identify all the major components:

Power Supply

Motherboard

Memory

Card Slots

Cards (sound, video, network)

CPU, heatsink and fan

Drives (floppy, hard and CD-ROM)


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powersupply

hard

drive

motherboard

COMPONENTS

CD-ROM

drive

floppydrive

cards


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Input and Output

Input devices convert data from the user into aform understood by the computer.

Output devices convert the processed 0s and 1sinto a form that the user can understand.

Hard copypermanently recorded, such as onpaper.

Soft copytemporarily recorded, such as on acomputer screen.


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The Keyboard

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

characters.


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Working with the Keyboard

Function keysare special purpose keys whose functiondepends on the software being used.

Cursor keysare used to move the cursor up, down, left,

or right.


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Variations on Keyboard Design

Ergonomic

to address repetitive stress

injuries

Wireless Folding

Half


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Keyboards

Portablekeyboardsandthumb pads

areincreasingly

being used

with portablePCs and

mobile

devices.


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Pointing Devices, Contd.

Electronic pens (light pen, stylus)

An alternative to the mouse to select objectsor 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


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Pointing Devices,Contd.

Touch screens

Used when other

input devices are

impractical.

Often used when

consumer input isrequired, as in

consumerkiosks.


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Pointing Devices,Contd.

Other common pointing devices

Joysticks and other gaming devices

Trackballs

Pointing sticks

Touch pads


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Pointing Devices


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Reading Tools

Optical-mark readers

Bar-code readers

Magnetic-inkcharacter readers

Wand readers

Pen scanners

Input devices read directly from paper and convertprinted information into bit patterns that can beprocessed by the computer.


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Digitizing the Real World

Scanner

Digital camera

Speech recognition Sensing devices


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Scanners

Scanners capture and digitize printed images.

There are several types of scanners:

Flatbed scanners

Handheld scanners

Sheet-fed scanners


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Scanners

Scanners (optical scanners) convert hard-copy images of text pages, photographs, and

drawings into digital form.

Types of scanners:

Flatbed

Sheet-fed

Handheld

Quality of scanned images

are measured by resolution.


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Optical Mark Readers (OMRs)

Read opticalmarks, such ason:

Exams

Census forms

Voting ballots

Lottery forms


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Bar-Code Readers

Bar codean optical code consisting ofseveral 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


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Optical Character Recognition

(OCR) Devices Optical charactersare designed to be

identifiable by humans as well as OCR device.

Widely used in turnaround documents, such as

monthly bills.


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Magnetic Ink Character

Recognition (MICR) Readers

MICR readerscan read the

specialmagneticcharactersand sort andprocessdocumentsaccordingly.

Used primarily for processing checks.


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Multimedia Input Devices

Digital cameras record data onto digital mediainstead of conventional film or tape.

Images can be transferred to a PC via a cable orthe storage media (such as a flash memory card

with a digital still camera).

Can be digital still camerasordigital videocameras.


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Digital Cameras

Digital cameras capture snapshots

and store them as bit patterns on

disks or other storage media.


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Multimedia Input Devices,

Contd.

Digital still cameras

Images are usually stored on flash memory cards.

Photos can usually be immediately previewed and deleted, ifneeded.

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.


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Contd. 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 Webcams.


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Contd. Audio input devices

Voice-input systems convert spoken words todigital data.

Voice input can be used to input data or

commands into a PC as well as fortelephony.

Music-input systemscan input and record music(either original compositions or via a CD or DVD

player).


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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.


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Output: From Pulses to People

Screen Output

Paper Output

Sound Output


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Screen Output

A monitor or video display terminal (VDT)

displays characters, graphics,

photographic

images, animation and video.

Video adapterconnects the monitor to thecomputer

VRAM or video memorya special portion ofRAM to hold video images (the more video

memory, the more detail of a picture

displayed)


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Display Devices

Display device characteristics

Color vs. monochrome displays

Size (measured diagonally)

Screen resolution

Graphic standards


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Display Devices, Contd.

CRT (cathode-ray tube) monitorsdisplay images

similar to conventional televisions.

Quality is measured in dot pitch.


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Screen Talk

Monitor size - measured as a diagonalline across the screen.

Pixels (or picture element) - tiny dots thatcompose a picture

Resolution- the number of pixels

displayed on the screen (the higher theresolution, the closer together the dots)


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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


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Examples of Color Depth

1-bit depth

16-bit depth8-bit depth

4-bit depth


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Monitor Classes

CRT (cathode ray

tube) LCD (liquid crystal display)


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Display Devices, Contd.

Flat-panel displaysform images bymanipulating electronically-charged chemicalsor gases between thin panes or glass orplastic.

Common types:

Liquid crystal displays (LCD)

Gas plasma

Used for monitors, televisions, handhelddevices, and other consumer products.


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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


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Paper Output

Printers produce

paper output or hardcopy

2 kinds of printers:

Impact printers

Non-impact

printers


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Impact Printers

Line printer

Used by mainframes to

produce massive printouts

Limited to printingcharacters

Dot matrix printer

Images created by amatrix of tiny dots

Low print quality

Low cost


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Non-impact Printers

A laser beam reflected

off

a rotating drum tocreate patterns of

electrical charges

Faster and moreexpensive

than dot matrix printer

High-resolution output

Laser Printer


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Laser Printers

The standard for business documents.

Work similarly to photocopy machines; printwith toner powder.

Are usually black and white, though colorlaser printers are available.

Fast print speed; print one page at a time.


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More on Non-impact Printers

Sprays ink onto paperto produce printed textand graphic images

Prints fewerpages/minute thanlaser printer

High-quality colorcosting less than laserprinter

Ink-jet Printer


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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.


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Special Purpose Printers

Photo printers

Bar-code printers

Label printers

Portable printers

Plotters and wide-format

ink-jet printers

Fax machines

Multifunction devices


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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.


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Output You Can Hear

A sound card allows the PCto accept microphone input,

play music and other sounds

through speakers orheadphones.

Synthesizers are included in

sound cards and havespecialized circuitry designed

to generate sounds

electronically.


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Multimedia Output Devices

Speakers

Voice-output

systems

Documents

01B - Input Output Devices and Hardware