1Copyright © Prentice Hall 2000 Input and Output Chapter 4 The User Connection.

1Copyright © Prentice Hall 2000

Input and Output

Chapter 4Chapter 4

The User ConnectionThe User Connection


Functions of Computer Systems

Recall that there are four main Recall that there are four main functions of computer systems.functions of computer systems.

Input Processing Output

SecondaryStorage


Input and Output

The computer user The computer user is very aware of is very aware of inputting inputting datadata and the output and the output ((processed processed informationinformation) that ) that is the result.is the result.


Inputting Data

• KeyboardKeyboard• MouseMouse• TrackballTrackball• Magnetic-ink Magnetic-ink

character character recognitionrecognition

• ScannerScanner• Optical mark Optical mark

recognitionrecognition

• Optical character Optical character recognitionrecognition

• Bar codesBar codes• Handwritten Handwritten

characterscharacters• Voice inputVoice input• Touch screensTouch screens• LookingLooking


Keyboard

A keyboard is similar to a typewriter A keyboard is similar to a typewriter keyboard. Not all keyboards are keyboard. Not all keyboards are traditional. Customized keyboards can be traditional. Customized keyboards can be found in business, schools, and homes.found in business, schools, and homes.


Mouse

The mouse movement corresponds The mouse movement corresponds to movement of the to movement of the pointerpointer (cursor) on the screen.(cursor) on the screen.

A mouse also has A mouse also has one or more one or more buttonsbuttons which allow which allow selection of items selection of items on a screen.on a screen.


Trackball

The trackball stays in one The trackball stays in one place while the user place while the user rolls the ball directly rolls the ball directly with one hand.with one hand.

Trackballs are ideal when Trackballs are ideal when a flat surface does not a flat surface does not exist.exist.


Magnetic-ink Recognition

The most common The most common example of example of characters made characters made of magnetic of magnetic particles can be particles can be seen on personal seen on personal checks.checks.


Scanner

A scanner is an A scanner is an optical recognition optical recognition system system that uses light to scan an image and that uses light to scan an image and convert it into electrical signals. convert it into electrical signals.

The signals are then processed so that the The signals are then processed so that the image appears on the computer monitor.image appears on the computer monitor.


Optical Mark Recognition

This technique uses a This technique uses a machine to sense machine to sense marks on a piece of marks on a piece of paper.paper.

Computer-graded answer Computer-graded answer sheets rely on optical sheets rely on optical mark recognition mark recognition (OMR) to score tests.(OMR) to score tests.

Exam

1. O O O O

2. O O O O3. O O O O4. O O O O

5. O O O O

a b c d


Optical Character Recognition (OCR)

OCR devices use a OCR devices use a light source to read light source to read special characters special characters or printed text.or printed text.

OCR devices can OCR devices can “read” pages in a “read” pages in a book or sale tags book or sale tags on store on store merchandise.merchandise.


Bar Codes

Bar codes appear on the product as a Bar codes appear on the product as a series of zebra-like stripes.series of zebra-like stripes.

Bar codes are used to identify a Bar codes are used to identify a product when read by a device product when read by a device called a called a bar code readerbar code reader..


Handwritten Characters

Machines can read Machines can read handwritten handwritten characters.characters.

However, the size, However, the size, completeness, and completeness, and legibility of the legibility of the handwriting must handwriting must follow rigid rules.follow rigid rules.

machines that can

read


HelloHal.

Voice Input

Speaking to a computer Speaking to a computer requires requires speech speech recognitionrecognition devices. devices.

The computer The computer processes the sounds processes the sounds into binary code and into binary code and can “learn” what the can “learn” what the code means.code means.

Hello

Hal.


Touch Screens

Touch screens Touch screens are designed are designed so that if so that if touched, the touched, the computer computer knows what knows what the person has the person has selected.selected.

Yes

No


Looking

In the future, input In the future, input might be might be gathered from gathered from our eye our eye movements, and movements, and watching images watching images that appear on that appear on our retina.our retina.


Output of Information

Useful information for the user can Useful information for the user can take on a variety of forms:take on a variety of forms:

• Computer screensComputer screens• PrintersPrinters• Voice outputVoice output• Music and soundMusic and sound


Computer Screens

Screen output is Screen output is known as known as soft copy soft copy because it is because it is intangible and intangible and temporary.temporary.

Most computer Most computer screens are of the screens are of the cathode ray cathode ray variety.variety.


Cathode Ray Tube (CRT)

Most CRT screens use Most CRT screens use raster scanning raster scanning to produce the image.to produce the image.

The image must be refreshed often. The image must be refreshed often. The rate of refreshing is called The rate of refreshing is called scan scan raterate..

The image we see actually consists of The image we see actually consists of dots (dots (pixelspixels) on the screen that are ) on the screen that are either illuminated or not.either illuminated or not.


Pixels

ResolutionResolution is determined is determined by the number of pixels by the number of pixels on the screen.on the screen.

The amount of space The amount of space between pixels is between pixels is dot dot pitchpitch, which determines , which determines image quality.image quality.


Resolution Just Gets Better

There are two There are two common common resolutions resolutions available today:available today:

SVGA -•800x600•1024x768•1280x1024•1600x1200XGA- more colors


Flat Screens

Some computer Some computer screens use liquid screens use liquid crystal technology.crystal technology.

LCDs are popular LCDs are popular with laptop with laptop computers.computers.


Terminals

Terminals integrate a monitor, Terminals integrate a monitor, keyboard and communications keyboard and communications link.link.

Smart terminals have their own Smart terminals have their own CPUCPU


Printers

A printer is an output device that A printer is an output device that produces a produces a hard copy hard copy of your work of your work (a printout on paper).(a printout on paper).

There are two ways to There are two ways to print onto paper:print onto paper:• ImpactImpact• Non-impactNon-impact


Impact Printers

An impact printer makes physical An impact printer makes physical contact with the paper to produce contact with the paper to produce an image.an image.

Impact printers are practical for print Impact printers are practical for print jobs in which jobs in which quantityquantity matters or matters or when multiple (carbon) copies are when multiple (carbon) copies are needed simultaneously.needed simultaneously.


Non-Impact Printers

Non-impact printers put the image Non-impact printers put the image on the page without physically on the page without physically striking the paper.striking the paper.

These printers are best when These printers are best when qualityquality is important.is important.


Voice Output

Synthesizing speechSynthesizing speech is is much easier for a much easier for a computer than computer than speech recognition.speech recognition.

There are two methods:There are two methods:• Synthesis by analysisSynthesis by analysis• Synthesis by ruleSynthesis by rule

HelloDave.


Synthesis by Analysis

In this method of speech synthesis, In this method of speech synthesis, the output device analyzes the the output device analyzes the input of a human voice speaking input of a human voice speaking words.words.

The words are stored and the sounds The words are stored and the sounds are processed.are processed.

Later, the computer “talks” by Later, the computer “talks” by reproducing the words as needed.reproducing the words as needed.


Synthesis by Rule

In this method of speech synthesis, In this method of speech synthesis, the output device applies a the output device applies a complex set of linguistic rules to complex set of linguistic rules to create artificial speech.create artificial speech.


Music and Sound Output

• May be as simple as May be as simple as attaching speakers attaching speakers to the computer.to the computer.

• For more serious For more serious output, add sound output, add sound chips to simulate chips to simulate different different instruments or instruments or sound effects.sound effects.

• Use MIDI to record Use MIDI to record and playback musical and playback musical compositionscompositions


Computer Graphics Output

Examples of this kind of output Examples of this kind of output include:include:

• Computer artComputer art• ScienceScience• SportsSports

• Business graphicsBusiness graphics• Video graphicsVideo graphics• CAD/CAMCAD/CAM• EducationEducation


Business Graphics

Business graphics is a Business graphics is a powerful way to turn powerful way to turn numerical data into numerical data into more meaningful more meaningful information.information.

April Sales by Teams (AA, BB, CC, and DD)

The addition of The addition of ccoolloorr increases understanding. increases understanding.


Video Graphics

Video graphics Video graphics combines combines computer computer graphicsgraphics and and soundsound, with the , with the ability to ability to animateanimate a series a series of frames.of frames.


TV’s Special Effects

Many television Many television programs and programs and movies rely on movies rely on the special the special effects made effects made possible with possible with video graphics video graphics technology.technology.


CAD/CAM

Computer-aided Computer-aided designdesign (CAM) and (CAM) and computer-aided computer-aided manufacturingmanufacturing use computers to use computers to design, build, and design, build, and test products.test products.


Digital Cameras

• Digital cameras take photographs and Digital cameras take photographs and store them internallystore them internally

• Photos are then sent to the computer Photos are then sent to the computer for output, or stored on disk.for output, or stored on disk.


Ethics and Data

Just because a computer will allow Just because a computer will allow you to input data and produce you to input data and produce new information as output, new information as output, doesn’t always mean it is legal or doesn’t always mean it is legal or right to do so.right to do so.


Ethics and Data

Is the situation described below Is the situation described below ethical?ethical?

Use computer software to Use computer software to substitute one person for another substitute one person for another in a photograph.in a photograph.


Ethics and Data

Is the situation described below Is the situation described below ethical?ethical?

Erase contents of e-mails that may Erase contents of e-mails that may help someone filing suit against your help someone filing suit against your company.company.


Conclusion

Newer input and output devices are Newer input and output devices are announced regularly.announced regularly.

Users reap the benefits of Users reap the benefits of improvements in performance and improvements in performance and ease of use. ease of use.

1Copyright © Prentice Hall 2000 Input and Output Chapter 4 The User Connection.

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Transcript of 1Copyright © Prentice Hall 2000 Input and Output Chapter 4 The User Connection.