Chapter Topics

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Chapter TopicsChapter TopicsChapter 2 Chapter 2 Looking at Computers: Looking at Computers:

Understanding the PartsUnderstanding the Parts

• Functions of a computerFunctions of a computer

• Data versus informationData versus information

• Bits and bytesBits and bytes

• Input devicesInput devices

• Output devicesOutput devices

• System unitSystem unit

• ErgonomicsErgonomics

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Computers Are Data Computers Are Data Processing DevicesProcessing Devices

• Computer’s four major functions:Computer’s four major functions:– Gathers data (users input data)Gathers data (users input data)– Processes data into informationProcesses data into information– Outputs data or informationOutputs data or information– Stores data and informationStores data and information

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Data vs. InformationData vs. Information

• Data: Representation of a fact, figure, or idea

• Information: Organized, meaningful data

Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall

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Bits and Bytes: Bits and Bytes: The Language of ComputersThe Language of Computers

• Bit– Binary digit– 0 or 1

• Byte– Eight bits

• Each letter, number, and character = a string of eight 0s and 1s

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How Much Is a Byte?How Much Is a Byte?


Name Abbreviation Number of Bytes Relative Size

Byte B 1 byte Can hold one character of data.

Kilobyte KB 1,024 bytes (210 bytes) Can hold 1,024 characters or about half of a double-spaced typewritten page.

Megabyte MB 1,048,576 bytes (220 bytes) Can hold approximately 768 pages of typed text.

Gigabyte GB 1,073,741,824 bytes (230 bytes) Approximately 786,432 pages of text; 500 sheets of paper is approximately 2 inches, so this represents a stack of paper 262 feet high.

Terabyte TB 1,099,511,627,776 bytes (240 bytes) This represents a stack of typewritten pages almost 51 miles high.

Petabyte PB 1,125,899,906,842,62 bytes (250 bytes)

The stack of pages is now 52,000 miles high, or approximately one-fourth the distance from the Earth to the moon.

Exabyte EB 1,152,921,504,606,846,976 bytes (260 bytes)

The stack of pages is now 52 million miles high, or just about twice the distance between the Earth and Venus.

Zettabyte ZB 1,180,591,620,717,411,303,424 bytes (270 bytes)

The stack of pages is now 52 billion miles high, some 20 times the distance between the Earth and Pluto.

Metric prefixesMetric prefixes

prefix abbrev # word

-- B 1 byte

kilo KB 1,000 bytes thousand

mega MB 1,000,000 bytes million

giga GB 1,000,000,000 bytes billion

tera TB 1,000,000,000,000 bytes Trillion

peta PB 1,000,000,000,000,000 bytes quadrillion

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Computer HardwareComputer Hardware

Hardware:

Any part of the computer you can touch.

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Computer SoftwareComputer Software

• Software: Programs that enable Software: Programs that enable hardware to perform different taskshardware to perform different tasks– Application softwareApplication software– System softwareSystem software

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Types of ComputersTypes of Computers

• Notebook: Portable computer

• Desktop: Used at a single location

• Mainframe: Supports hundreds of users simultaneously

• Supercomputer: Performs complex calculations rapidly

• Embedded: Self-contained computer performing dedicated functions


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Input DevicesInput Devices• Devices used to enter information or Devices used to enter information or

instructions into the computerinstructions into the computer– KeyboardKeyboard– Mouse/Mouse/

pointing devicepointing device– Microphone Microphone – ScannerScanner– Digital cameraDigital camera– StylusStylus

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KeyboardsKeyboards• The QWERTY The QWERTY

layout is standard layout is standard on most PCson most PCs

• Enhanced Enhanced keyboard features keyboard features include number, include number, function, and function, and navigation keysnavigation keys..

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Notebook KeyboardNotebook Keyboard• trackpointtrackpoint• touchpadtouchpad• number pad number pad • Notebook keys – Notebook keys –

fn key in fn key in conjunction with conjunction with function key function key does special does special function such as function such as volumevolume

trackpoint

Touchpad

Fn key

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Dvorak KeyboardsDvorak Keyboards

• Puts the most commonly used keys on “home keys”Puts the most commonly used keys on “home keys”• Reduces distance of finger stretchesReduces distance of finger stretches• Not enough interest to change from QWERTY Not enough interest to change from QWERTY

thoughthough

Virtual laser, Tablet and stylusVirtual laser, Tablet and stylus

• Virtual laser keyboard

• Configurable keyboard


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Digital penDigital pen

• Stores what you Stores what you “write”, later transfer “write”, later transfer to computerto computer

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© 2008 Prentice-Hall, Inc. 16

Wireless RF keyboardWireless RF keyboard• With the RF (radio With the RF (radio

frequency) wireless frequency) wireless technology, the keyboard technology, the keyboard contains a transmitter that contains a transmitter that transmits the radio waves transmits the radio waves to a receiver that sits next to a receiver that sits next to the keyboard and is to the keyboard and is attached to the tower. attached to the tower. (upto 100 ft)(upto 100 ft)

• Bluetooth wireless Bluetooth wireless keyboard is a shorter keyboard is a shorter range wirelessrange wireless

RF keyboard

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MiceMice• Optical mouseOptical mouse

– Doesn’t need as dirtyDoesn’t need as dirty

– no mouse pad necessaryno mouse pad necessary

• TrackballTrackball

– Easier on wristsEasier on wrists

– Stays stationary Stays stationary

on deskon desk

• Wireless Wireless

– Use radio or light wavesUse radio or light waves

• Integrated pointing deviceIntegrated pointing device

– Touchpad Touchpad

– TrackpointTrackpoint

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Other Input DevicesOther Input Devices• ScannersScanners

– TextText– Images Images

• Digital camerasDigital cameras– Images Images – Video Video

Flatbed scanner

Handheld scanner

Digital camera

Camcorder

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Other Input DevicesOther Input Devices• Game controllers

• Touchscreens– DS game– Tablet PC (see pic)

• Digital pens


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Image InputImage Input• Digital cameras,

camcorders, and cell phones– Pictures – Video

• Webcams– Live video


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Inputting SoundInputting Sound• Microphones Microphones

used for:used for:– PodcastsPodcasts– Video-Video-

conferencingconferencing– Internet phone Internet phone

callscalls– Speech Speech

recognition recognition

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Input Devices for the Input Devices for the Physically ChallengedPhysically Challenged

• Visual impairmentsVisual impairments– Voice recognitionVoice recognition– Keyboards with large keysKeyboards with large keys– On-screen keyboardsOn-screen keyboards

• Motor control issuesMotor control issues– Special trackballsSpecial trackballs– Head-mounted devicesHead-mounted devices

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Output DevicesOutput Devices

• Send processed data out of the computerSend processed data out of the computer– MonitorsMonitors– PrintersPrinters

• Output devices make:Output devices make:– Soft copies (video, sounds, control signals)Soft copies (video, sounds, control signals)– Hard copies (print)Hard copies (print)


Monitor Types and advantagesMonitor Types and advantagesCRT CRT Cathode Ray TubeCathode Ray Tube

– Less expensiveLess expensive– Better viewing anglesBetter viewing angles– More adjusting allowed of of More adjusting allowed of of

the resolution settingsthe resolution settings– Better color accuracyBetter color accuracy– Preferred for gamingPreferred for gaming– A 17” monitor IS less than17”A 17” monitor IS less than17”– legacylegacy

LCD LCD Liquid Crystal DisplayLiquid Crystal Display– Price is droppingPrice is dropping– Uses far less spaceUses far less space– More energy efficientMore energy efficient– More More environmentally friendlyenvironmentally friendly– Less eye strainLess eye strain– A 17’’ monitor IS 17”A 17’’ monitor IS 17”– brighterbrighter

• Screens are grids made up of millions of pixelsScreens are grids made up of millions of pixels ..– (pixel = picture elements, dots on screen)(pixel = picture elements, dots on screen)

– Each pixel is composed of red, blue, and green subpixels

• LCDs: Liquid crystal, light waves, etc result in LCDs: Liquid crystal, light waves, etc result in variations of red, green blue colors of images variations of red, green blue colors of images formed n scrnformed n scrn

(CRTs: Pixels illuminated by electron beam (CRTs: Pixels illuminated by electron beam

that passes back/forth across screen.)that passes back/forth across screen.)

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LCD Monitor FeaturesLCD Monitor Features

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LCD Quality FactorsLCD Quality Factors(recommended measures in parentheses) :(recommended measures in parentheses) :

• ResolutionResolution - depends on # of pixels on screen; - depends on # of pixels on screen; (native resolution is the (native resolution is the maximum resolutionmaximum resolution))

• Viewing angle Viewing angle - poorer angles than the CRT - poorer angles than the CRT (degrades after 150 degrees) (degrades after 150 degrees)

• ContrastContrast ratioratio - Diff between brightest white & - Diff between brightest white & darkest black darkest black (400:1 or 1000:1)(400:1 or 1000:1)

• BrightBrightness ness - amt of - amt of lightlight when showing pure when showing pure whitewhite (300 cd/m(300 cd/m22))

• Response time – time for pixel to change Response time – time for pixel to change color color (smaller # better; for movies, games)(smaller # better; for movies, games)

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Screen SizeScreen Size• 21” monitor: 1680x1050 pixels (typical

resolution)

• 19” monitor: Some resolutions: 1440x900, 1280x1024

– Need 1920x1080 for hi-def movies• Wide screen vs. standard 4:3 ratio; wide good

for 2 documents viewed at once...• Large resolution fits more on screen (images are

smaller); Small res fits less (images are larger)


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Other Video OutputOther Video Output• Touch-screen monitorsTouch-screen monitors

– Double as both input and output devicesDouble as both input and output devices

• Monitors w/ built-in cam, mic, card reader, USB hub

• Data projectors Data projectors – Project a computer image to wall for Project a computer image to wall for

sharing with groupsharing with group

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Printers Printers

• Impact printersImpact printers– Dot-matrixDot-matrix

• Nonimpact printersNonimpact printers– InkjetInkjet– Laser Laser

• Specialty printersSpecialty printers– All-in-oneAll-in-one– PlottersPlotters– Thermal printersThermal printers

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Nonimpact PrintersNonimpact Printers

• Inkjet– Less expensive device– Print high-quality color

images cost effectively

• Laser– More expensive device– Faster printing speed– Color lasers are

becoming less expensive



Nonimpact PrintersNonimpact PrintersInkjet and LaserInkjet and Laser

• Inkjet Inkjet ((spray tiny drops of ink. spray tiny drops of ink. ))

– Entry level model is less Entry level model is less expensive expensive

– Full color printing – Full color printing – excellent choice for excellent choice for photo printingphoto printing

• Laser (uses toner)Laser (uses toner)– There are B & W laser There are B & W laser

printers and color printers and color laser printers laser printers (Color (Color lasers very expensive)lasers very expensive)

– Excellent quality, quietExcellent quality, quiet

When purchasing a printer consider price of consumables (ex: cartridges and toner), speed (ppm, pages per minute), resolution (dpi, dots per inch) , memory, color

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The MotherboardThe Motherboard

• CPUCPU

• RAM (S+T)RAM (S+T)

• Expansion Expansion cards and cards and slotsslots

• Built-in Built-in componentscomponents

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Expansion CardsExpansion Cards

• Add functionsAdd functions

• Provide new connections for peripheral Provide new connections for peripheral devicesdevices

• Common types:Common types:– SoundSound– Modem (telephone)Modem (telephone)– Video (VGA or graphics)Video (VGA or graphics)– Network (NIC=network interface card)Network (NIC=network interface card)

RAM vs. ROMRAM vs. ROM

• Random access memory (RAM):– Stores instructions

and data– Temporary

(volatile) storage– Consists of several

memory cards or modules

• Read-only memory (ROM):– Stores start-up

instructions– Permanent storage


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Memory ModuleMemory Module• Random access memory (RAM)Random access memory (RAM)

• Stores instructions and data temporarily Stores instructions and data temporarily – (copy of program instructions and current files (copy of program instructions and current files

goes into RAM)goes into RAM)

• Temporary (volatile) storageTemporary (volatile) storage

• Operates in nanosecondsOperates in nanoseconds

• Common size: 2-8GBCommon size: 2-8GB

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Central Processing Unit (CPU)Central Processing Unit (CPU)• Referred to as the “brains” of the computerReferred to as the “brains” of the computer• Controls all functions of the computerControls all functions of the computer• Processes all commands and instructionsProcesses all commands and instructions• Can perform billions of tasks per second Can perform billions of tasks per second • Common speed: 2-3 ghz (gigahertz)Common speed: 2-3 ghz (gigahertz)• 3 ghz = ~ 3 billion machine cycles per sec3 ghz = ~ 3 billion machine cycles per sec

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CPU Performance MeasuresCPU Performance Measures• Speed - common 2-3 ghz

– 3 GHz ~ 3 billion machine cycles per sec– Megahertz (MHz)– Gigahertz (GHz);

• Cores (simultaneous paths executing instruct’s; see picture on right)

– Single– Dual– Quad


Drive BaysDrive Bays• Internal drive bays:

– Cannot be accessed from outside the system

– Are reserved for internal hard drives

• External drive bays:– Can be accessed from

outside the system– CD or DVD drives– Floppy and Zip drives

(legacy technology)


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The Front PanelThe Front Panel

• Power controlPower control• Drive baysDrive bays• Memory card Memory card

readerreader• Productivity Productivity

portsports

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Hard DriveHard Drive


• Permanent storage Permanent storage • Internal or external versionsInternal or external versions• Stores data, program instructions as they are runningStores data, program instructions as they are running• (Completes tasks in millisecs vs RAM’s nanosecs.)(Completes tasks in millisecs vs RAM’s nanosecs.)• (Spin rate: 5400, 7200 rpm) (Spin rate: 5400, 7200 rpm) • Common: 500 GB, 640 GB, 1TB, 2TB Common: 500 GB, 640 GB, 1TB, 2TB

– (T=Tera, trillion)(T=Tera, trillion)

Optical StorageOptical Storage

• Compact discs (CDs)

• Digital video discs (DVDs)

• Blu-ray discs (BDs)


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StorageStorage MediaMedia CapabilitiesCapabilitiesSee p71 (8e), teacher notesSee p71 (8e), teacher notes

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Typo: DVD DL is 8.5 GB not 88.5

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Flash Drives/Flash MemoryFlash Drives/Flash Memory


• Flash drives (jump drives)– Newer storage

alternative– Plug into USB ports

• Flash memory cards– Slide into slots in the

system

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Types of PortsTypes of Ports



Ports for peripheral devicesPorts for peripheral devicesTypes of ports w/ speeds (= transfer rates):Types of ports w/ speeds (= transfer rates):– Serial 115K bps, Serial 115K bps, – Parallel 500K bpsParallel 500K bps– USB USB 480M480M bps (2.0)bps (2.0)– USB USB 4800M bps 4800M bps (3.0)(3.0)– Ethernet 100M,1000M bpsEthernet 100M,1000M bps– Tele. modem 56K bpsTele. modem 56K bps– FireWire (or 1394) FireWire (or 1394)

400M bps400M bps, 800M bps, and, 800M bps, and3.2G bps (= 3.2G bps (= 3200M bps3200M bps))

– Audio ports Audio ports – VGA (monitor), DVI, s-videoVGA (monitor), DVI, s-video– HDMIHDMI

Adding PortsAdding Ports

• Expansion cards:– New port

standards

• Expansion hubs:– Enable several

devices to be connected to a port


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Power ControlsPower ControlsPower-on button: Turns on system; Use

Shut Down procedure or may use Power button to turn off.

• Called a cold boot when turned on for the first time that day (Warm boot is restart)

• Keep computer on but use conservation of energy: Sleep mode, Hibernate

• Only turn off computer if use it very little• Change power settings: Control Panel

(icon view) > Power OptionsCopyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall


Ergonomics (1)Ergonomics (1)• Ergonomics – procedures, Ergonomics – procedures,

equipment for minimizing injury equipment for minimizing injury or discomfort while using the or discomfort while using the computer (minimize RSI - computer (minimize RSI - repetitive stress injury)repetitive stress injury)

• Steps to follow:Steps to follow:– Position monitor correctly (eyse Position monitor correctly (eyse

at top of monitor)at top of monitor)– Use adjustable chair (back of Use adjustable chair (back of

knees not pressed against knees not pressed against chair that is too high, feet on chair that is too high, feet on floor)floor)

– Wrists flat over keyboard, not Wrists flat over keyboard, not presses on edge of tablepresses on edge of table

– Take breaksTake breaks– Ensure adequate lightingEnsure adequate lighting


Ergonomics (2)Ergonomics (2)

• Play PMPs (personal media players) Play PMPs (personal media players) at 60 decibels or lessat 60 decibels or less

• Small screens – blink often, take a break Small screens – blink often, take a break to focus at 8ftto focus at 8ft

• Backpack – place over both shoulders Backpack – place over both shoulders not onenot one

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Chapter 2 Summary QuestionsChapter 2 Summary Questions• What are the 4 main functions of a computer?What are the 4 main functions of a computer?• What is the difference between data and information?What is the difference between data and information?• What are bits and bytes, and how are they measured? What are bits and bytes, and how are they measured? • What devices do you use to get data into the computer?What devices do you use to get data into the computer?• What devices do you use to get information out of the What devices do you use to get information out of the

computer?computer?• What’s on the motherboard?What’s on the motherboard?• Where are programs and information stored?Where are programs and information stored?• How are devices connected to the computer?How are devices connected to the computer?• How do you set up your computer to avoid strain and How do you set up your computer to avoid strain and

injury?injury?

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