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Computer HardwareComputer Hardware

Unit BUnit B

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ObjectivesObjectives

Introduce Storage TechnologyIntroduce Storage Technology

Compare Storage TechnologiesCompare Storage Technologies

Compare Storage Media and Compare Storage Media and DevicesDevices

Explore Floppy Disk TechnologyExplore Floppy Disk Technology

Explore Hard Disk TechnologyExplore Hard Disk Technology

Explore CD/DVD TechnologyExplore CD/DVD Technology

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ObjectivesObjectives

Explore Solid State StorageExplore Solid State StorageExamine Input DevicesExamine Input DevicesCompare Display DevicesCompare Display DevicesCompare PrintersCompare PrintersUnderstand Expansion Slots, Understand Expansion Slots, Cards, and PortsCards, and PortsExplore Peripheral DevicesExplore Peripheral Devices

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Storage TechnologyStorage Technology

Storage Medium: holds dataStorage Medium: holds data– Disk, CD, DVDDisk, CD, DVD

Storage Device: mechanical Storage Device: mechanical apparatus that records and apparatus that records and retrieves data from mediumretrieves data from medium– Disk drives, CD drivesDisk drives, CD drives

Storage = Medium + DeviceStorage = Medium + Device

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Storage ProcessStorage Process

Data copied from storage Data copied from storage device to RAMdevice to RAMProcessed in RAM Processed in RAM – Volatile (temporary) high speed storageVolatile (temporary) high speed storage– RAM is connection between the RAM is connection between the

storage device and mediastorage device and media

Data copied back to storage Data copied back to storage medium (permanent)medium (permanent)Storing data is writing/saving Storing data is writing/saving filefileRetrieving data is Retrieving data is reading/loading/opening filereading/loading/opening file

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Storage ProcessStorage Process

A computer works with data that has A computer works with data that has been coded to be represented by 1s been coded to be represented by 1s and 0s (binary system)and 0s (binary system)

When data is stored, 1s and 0s When data is stored, 1s and 0s converted into signalsconverted into signals

The transformation of 1s and 0s The transformation of 1s and 0s depends on the storage technologydepends on the storage technology

Data representationData representation makes it makes it possible to convert letters, sounds, possible to convert letters, sounds, and images into electronic symbolsand images into electronic symbols

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Storage ComparisonStorage Comparison

•Three main types of storage technologies for PCs:

•Magnetic–Hard disk, floppy disk, zip disk and Hard disk, floppy disk, zip disk and tapetape

•Optical–CD and DVDCD and DVD

•Solid stage–Cards, pens, and sticksCards, pens, and sticks

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Magnetic StorageMagnetic Storage

Magnetizes microscopic Magnetizes microscopic particles on medium particles on medium surfacesurface

Permanent, but Permanent, but modifiablemodifiable

Read-write headRead-write head

Not very durableNot very durable

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Floppy DisksFloppy Disks and Drives and Drives

Floppy disk characteristicsFloppy disk characteristics– Typically 3½ inches in diameter.Typically 3½ inches in diameter.– Typically hold 1.44 megabytes.Typically hold 1.44 megabytes.– Inserted into Inserted into floppy disk drive floppy disk drive to be read to be read

from or written to.from or written to.

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Floppy Disks and Drives, Floppy Disks and Drives, Cont’d.Cont’d.

Disk is divided into Disk is divided into trackstracks, , sectorssectors, and , and clustersclusters..

The disk’s The disk’s file directoryfile directory keeps track of the keeps track of the contents of the disk so contents of the disk so files can be retrieved files can be retrieved (by filename) at a later (by filename) at a later time.time.

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Floppy Disks and Drives, Floppy Disks and Drives, Cont’d.Cont’d.

Using floppy disksUsing floppy disks– Must be inserted into the proper drive in Must be inserted into the proper drive in

the proper direction. the proper direction. – Should not be removed when the disk is Should not be removed when the disk is

being accessed.being accessed.

High-capacity removable High-capacity removable magnetic disks and drivesmagnetic disks and drives– Zip disks (750 MB)Zip disks (750 MB)– SuperDisks (240 MB) SuperDisks (240 MB)

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Hard Disk DrivesHard Disk Drives

Hard drive characteristicsHard drive characteristics

– Metal disk onto which data is stored Metal disk onto which data is stored magnetically.magnetically.

– Disks are usually permanently sealed inside the Disks are usually permanently sealed inside the hard drive—allows faster speeds and storage of hard drive—allows faster speeds and storage of more data than removable systems. more data than removable systems.

– Can be internal or external.Can be internal or external.

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Hard Disk Drives, Hard Disk Drives, Cont’d.Cont’d.

Hard drive characteristics, Hard drive characteristics, cont’dcont’d

– Organized into tracks, sections, clusters, and Organized into tracks, sections, clusters, and cylinderscylinders (the collection of tracks located in (the collection of tracks located in the same location on a set of hard disk the same location on a set of hard disk surfaces).surfaces).

– Read/write head doesn’t touch the surface of Read/write head doesn’t touch the surface of the disk.the disk.

– Bumping PC when disk is being accessed or Bumping PC when disk is being accessed or dust or other obstacles on a hard-disk system dust or other obstacles on a hard-disk system can cause a can cause a head crash head crash and damage the and damage the surface of the disk.surface of the disk.

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Hard Disk Drives, Hard Disk Drives, Cont’d.Cont’d.

Disk access time.Disk access time.– Factors: seek time, rotational delay, Factors: seek time, rotational delay,

data movement timedata movement time

Can use multiple Can use multiple partitions.partitions.Disk cacheDisk cache—s—strategy for trategy for speeding up system speeding up system performance.performance.Hard drive standards (EIDE, Hard drive standards (EIDE, SCSI, Fibre Channel, USB)SCSI, Fibre Channel, USB) . .

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Hard Disk Drives, Hard Disk Drives, Cont’d.Cont’d.

Portable hard drive Portable hard drive systemssystems

Offer large storage Offer large storage capacities and capacities and portability. portability. – Either entire drive Either entire drive

or just hard disk or just hard disk cartridge is cartridge is transported.transported.

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Hard Disk Drives, Hard Disk Drives, Cont’d.Cont’d.

Storage systems for large computer Storage systems for large computer systems and networkssystems and networks– Storage servers containing racks of hard Storage servers containing racks of hard

drives.drives.– Network attached storage (NAS).Network attached storage (NAS).– Storage area networks (SANs).Storage area networks (SANs).– RAID (for increased performance and/or RAID (for increased performance and/or

fault tolerance).fault tolerance).

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Optical Disc SystemsOptical Disc Systems

Laser beams write and read data packed at very Laser beams write and read data packed at very tight storage densities, many times finer than that tight storage densities, many times finer than that of a typical magnetic diskof a typical magnetic disk..

Are typically 4½-inch discs, but can be a variety of Are typically 4½-inch discs, but can be a variety of shapes and sizes.shapes and sizes.

Data is stored optically on a continuous spiral track.Data is stored optically on a continuous spiral track.

Can be CDs or DVDs.Can be CDs or DVDs.

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Read-Only Discs: CD-ROM and Read-Only Discs: CD-ROM and DVD-ROM DiscsDVD-ROM Discs

CD-ROM discsCD-ROM discs cannot be written to or erased cannot be written to or erased and typically hold 650 MB (e.g. music CDs). and typically hold 650 MB (e.g. music CDs).

DVD-ROM discs DVD-ROM discs are similar to CD-ROM are similar to CD-ROM discs, but have higher capacity of 4.7 GB to discs, but have higher capacity of 4.7 GB to 17 GB (e.g. movie DVDs).17 GB (e.g. movie DVDs).

Data is stored by burning Data is stored by burning pits pits into the disc into the disc surface that can be read using a laser beam.surface that can be read using a laser beam.

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Optical StorageOptical Storage

Stores data as microscopic light Stores data as microscopic light and dark spots on disk surfaceand dark spots on disk surface

Pits and landsPits and lands

Uses laser lightsUses laser lights

More durableMore durable

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Solid Stage StorageSolid Stage Storage

Stores data in a non-volatile, erasable, low-Stores data in a non-volatile, erasable, low-power chippower chipData is organized in a microscopic grid of Data is organized in a microscopic grid of cellscellsA card reader transfers data between the A card reader transfers data between the card and computercard and computerDurable through temperature changes, Durable through temperature changes, vibrations, and magnetic fieldsvibrations, and magnetic fieldsGood for digital cameras and MP3 playersGood for digital cameras and MP3 playersVery high costVery high cost

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Comparing Storage DevicesComparing Storage Devices

VersatilityVersatility

DurabilityDurability

SpeedSpeed– Access timeAccess time– MillisecondsMilliseconds– Random vs. sequential accessRandom vs. sequential access– Data transfer rateData transfer rate

CapacityCapacity– KB, MB, GB, TBKB, MB, GB, TB– Disk densityDisk density

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Comparing Storage DevicesComparing Storage Devices

Device Capacity Comments

Floppy disk 1.44 MB Cannot hold large files

SuperDisk 120 or 240 MBFull-system backup requires multiple disks

Zip disk 100, 250, 750 MBFull-system backup requires multiple disks

Fixed disk80 GB (avg)

Fast, convenient, economical, high storage. Susceptible to damage or theft

External hard drive 80 GB (avg)

Drive can be removed and locked in a secure location

CD-R 700 MBLimited capacity & shelf-life, cannot be reused

CD-RW 700 MBLimited capacity, reusable

Writable DVD 4.7 GBStandards still in development

Tape 30 GB (avg) Good capacity, but slow

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Adding Storage DevicesAdding Storage Devices

UpgradingUpgrading

System Unit System Unit contains drive bayscontains drive bays– 5 ¼” or 3 ½”5 ¼” or 3 ½”– Access from either Access from either

outside or insideoutside or inside

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Floppy DisksFloppy Disks

Advantages: Advantages: – Portable, inexpensive, removablePortable, inexpensive, removable

Disadvantages:Disadvantages:– Low storage capacity of 3 ½” disksLow storage capacity of 3 ½” disks– Slower than hard disk driveSlower than hard disk drive

High Density (HD or HDD)High Density (HD or HDD)– HD DS means “high density, double-HD DS means “high density, double-

sided”sided”

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Floppy DisksFloppy Disks

3½” disk: 1.44 MB 3½” disk: 1.44 MB

Zip disks (Iomega): 100, 250 and 750 MBZip disks (Iomega): 100, 250 and 750 MB

SuperDisks (Imation): SuperDisks (Imation): 120 or 240 MB120 or 240 MB

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Hard Disks (Fixed Disks)Hard Disks (Fixed Disks)

One or more platters with read/write headsOne or more platters with read/write headsCapacity averages 80 GBCapacity averages 80 GBVery fast access times (rpm)Very fast access times (rpm)Platters divided into tracks, sectors, Platters divided into tracks, sectors, cylindercylinderController (circuit board)Controller (circuit board)– Ultra ATA, EIDE, SCSIUltra ATA, EIDE, SCSI

DMA transfers data directly from drive to DMA transfers data directly from drive to RAM RAM Head CrashHead Crash

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Tape StorageTape Storage

Sequential storage stores data in Sequential storage stores data in long sequence of bitslong sequence of bits– Stretches from one end of tape to anotherStretches from one end of tape to another– Makes it slower to access than hard driveMakes it slower to access than hard drive– Hundreds or thousands of feet of tapeHundreds or thousands of feet of tape

Tape cartridge is removableTape cartridge is removable

Internal or external modelsInternal or external models

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CD TechnologyCD Technology

CD-ROM:CD-ROM: Compact Disk Read-Only Compact Disk Read-Only MemoryMemory– Manufactured; cannot change; 680 MBManufactured; cannot change; 680 MB

CD-R:CD-R: Compact Disk Recordable Compact Disk Recordable– You record; cannot be erased or modifiedYou record; cannot be erased or modified

CD-RW:CD-RW: Compact Disk Rewritable Compact Disk Rewritable– You record; can erase and modifyYou record; can erase and modify

Archiving DataArchiving Data

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DVD TechnologyDVD Technology

Digital Video DiskDigital Video Disk

Originally alternative to VCROriginally alternative to VCR

4.7 GB4.7 GB

ManufacturedManufactured

Can play CD-ROM and most CD-Can play CD-ROM and most CD-Rs and CD-RWsRs and CD-RWs

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Solid State StorageSolid State Storage

Circuitry arranged in a gridCircuitry arranged in a grid– Each grid cell has 2 transistors (gates)Each grid cell has 2 transistors (gates)– Open gates are 1s; Closed gates are 0sOpen gates are 1s; Closed gates are 0s

Data is non-volatileData is non-volatile– Chip retains data without powerChip retains data without power

Some devices require a card readerSome devices require a card readerExamples:Examples:– USB flash drive, CompactFlash cards, USB flash drive, CompactFlash cards,

MultiMedia cards, Secure Digital cards, and MultiMedia cards, Secure Digital cards, and SmartMedia cardsSmartMedia cards

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Solid State StorageSolid State Storage

Why use solid stage storage?Why use solid stage storage?– Data can be easily transferred between Data can be easily transferred between

devices such as digital camera to devices such as digital camera to computer, OR computer to MP3 playercomputer, OR computer to MP3 player

– Cards can be reusedCards can be reused– Can transfer data between computersCan transfer data between computers

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Other Types of Storage Systems, Other Types of Storage Systems, Cont’dCont’d

Smart cardSmart card:: credit-card-sized credit-card-sized piece of plastic that contains some piece of plastic that contains some type of computer circuitry.type of computer circuitry.Holds less than a few megabytes.Holds less than a few megabytes.– Commonly used to store prepaid amounts Commonly used to store prepaid amounts

of digital cash or personal information.of digital cash or personal information.

Smart card readers Smart card readers are attached are attached to a PC or built into a cell phone, to a PC or built into a cell phone, keyboard, or other device.keyboard, or other device.

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Input DevicesInput Devices

KeyboardsKeyboards– Most computers have oneMost computers have one– Typing keypad, navigation keypad, Function Typing keypad, navigation keypad, Function

keys, Modifier keyskeys, Modifier keys

Pointing DevicesPointing Devices– Manipulate on-screen pointer and graphical Manipulate on-screen pointer and graphical

controlscontrols– Mouse, pointing stick, TrackPoint, trackpad, Mouse, pointing stick, TrackPoint, trackpad,

trackball, joy sticktrackball, joy stick

Also: scanners, digital cameras, Also: scanners, digital cameras, graphics tablets, microphones, graphics tablets, microphones, electronic instrumentselectronic instruments

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Display DevicesDisplay Devices

Graphics cardGraphics card– Video memory, AGP expansion cardVideo memory, AGP expansion card– Accelerator technologyAccelerator technology

CRT: Cathode Ray TubeCRT: Cathode Ray Tube– Inexpensive and dependableInexpensive and dependable

LCD: Liquid Crystal DisplayLCD: Liquid Crystal Display– Expensive; found on notebooksExpensive; found on notebooks– Limited viewing anglesLimited viewing angles– Active Matrix or TFT (thin film transistor)Active Matrix or TFT (thin film transistor)

PlasmaPlasma– Illuminates miniature fluorescent lightsIlluminates miniature fluorescent lights– Compact, light, expensiveCompact, light, expensive

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Display Device Image QualityDisplay Device Image Quality

Screen size (13” to 21”)Screen size (13” to 21”)– vis (viewable image size)vis (viewable image size)

Dot pitch (dp)Dot pitch (dp)– Distance between like-colored pixelsDistance between like-colored pixels– .26 or .23 typical (smaller is better).26 or .23 typical (smaller is better)

ResolutionResolution– Horizontal and vertical pixels on screenHorizontal and vertical pixels on screen– 640 x 480, 800 x 600 and 1024 x 768640 x 480, 800 x 600 and 1024 x 768

Color or Bit DepthColor or Bit Depth– Number of colors that can be displayedNumber of colors that can be displayed– 24-bit (true color) = millions of colors24-bit (true color) = millions of colors

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Printer Comparison CriteriaPrinter Comparison Criteria

Resolution (dpi)Resolution (dpi)

Materials Materials

CostCostQuality Quality

vs. vs.

PricePrice

Speed (ppm or cps)Speed (ppm or cps)

Duty CycleDuty Cycle

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Printer TypesPrinter Types

Ink Jet printerInk Jet printer

Solid Ink printerSolid Ink printer

Thermal Transfer printerThermal Transfer printer

Dye Sublimation printerDye Sublimation printer

Laser printerLaser printer

Dot Matrix printerDot Matrix printer

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Ink Jet PrinterInk Jet Printer

Nozzle-like print Nozzle-like print head sprays inkhead sprays ink

Low costLow cost

Can smudgeCan smudge

Color; black and Color; black and whitewhite

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Solid Ink PrinterSolid Ink Printer

Crayon-like ink is melted and Crayon-like ink is melted and sprayedsprayed

Vibrant colors on most types of Vibrant colors on most types of paperpaper

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Thermal Transfer PrinterThermal Transfer Printer

Uses wax that is meltedUses wax that is melted

Needs special paper/transparenciesNeeds special paper/transparencies

ExpensiveExpensive

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Dye Sublimation PrinterDye Sublimation Printer

Like wax transfer, but uses Like wax transfer, but uses heated dyeheated dye

Need special paperNeed special paper

Excellent color qualityExcellent color quality

ExpensiveExpensive

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Laser PrinterLaser Printer

Same technology as photocopierSame technology as photocopier

FaxFax

High qualityHigh quality

FastFast

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BussesBusses

Data Bus: circuits on which Data Bus: circuits on which data travels within the data travels within the computercomputer– Between RAM and CPUBetween RAM and CPU– Between RAM and storage Between RAM and storage

devicesdevices

Expansion BusExpansion Bus– Part of data bus between RAM Part of data bus between RAM

and the peripheralsand the peripherals

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Expansion Slots and CardsExpansion Slots and Cards

Cards also called Cards also called expansion boards, expansion boards, controller cards, adapterscontroller cards, adapters

Desktops have 4 to 8 slotsDesktops have 4 to 8 slots

Standard cardsStandard cards– Graphics or video cardGraphics or video card– Modem cardModem card– Sound cardSound card– Network cardNetwork card

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Expansion Slot TypesExpansion Slot Types

ISA:ISA: Industry Standard Architecture Industry Standard Architecture– Older; modems and slow devicesOlder; modems and slow devices

PCI:PCI: Peripheral Component Peripheral Component InterconnectInterconnect– Fast; graphics, sound, videoFast; graphics, sound, video

AGP:AGP: Accelerated Graphics Port Accelerated Graphics Port– Fast; graphicsFast; graphics

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PCMCIA (PC Card)PCMCIA (PC Card)

Personal Computer Memory Personal Computer Memory Card International AssociationCard International Association

Found on notebook computersFound on notebook computers

Type I, II, IIIType I, II, III

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Expansion PortsExpansion Ports

Jacks or connectorsJacks or connectors

Mouse, keyboard, Mouse, keyboard, serial, USBserial, USB

CablesCables

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USB portsUSB ports

Most popular for connecting Most popular for connecting peripheral devicesperipheral devices

Most computers have severalMost computers have several

Mouse, scanners, joysticks, USB Mouse, scanners, joysticks, USB Flash drivesFlash drives

Windows automatically Windows automatically recognizes most USB devicesrecognizes most USB devices

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PeripheralsPeripherals

Equipment attached to computer Equipment attached to computer to increase its functionalityto increase its functionality

Projection devices, scanners, Projection devices, scanners, Web cam, joy stickWeb cam, joy stick

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PeripheralsPeripherals

Connected through cables to the Connected through cables to the motherboard through a portmotherboard through a port– May require expansion card May require expansion card – Use grounding equipment for safetyUse grounding equipment for safety– Device driver software tells computer Device driver software tells computer

how to interact with devicehow to interact with device– PnP (Plug and Play) recognizes device PnP (Plug and Play) recognizes device

once it is connectedonce it is connected

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IssueIssue

Why Recycle Computers?Why Recycle Computers?

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Computer HardwareComputer Hardware

EndEnd