Computers © 2005 Prentice-Hall, Inc.Slide 1. Computers Chapter 5 Storage and Input/Output Devices...

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Computers

Chapter 5

Storage and Input/Output Devices

ComputersChapter 5 – Storage and Input/Output

Devices

Objectives Understand the various types of magnetic disk storage devices Understand the various types of optical laser disc storage devices Understand common input devices Understand common output devices

ComputersStorage and Input/Output Devices

Mass Storage Magnetic

DiskTape

Optical laser

AccessRandom or direct access

Computer can go directly to the desired information (magnetic disk/optical laser disc)

Sequential access – data in front of the desired data must be read first (magnetic tape)

Type of Magnetic Disks Interchangeable – can be moved from computer to computer Fixed – stays with one computer

Type of Magnetic DisksOffline – not available to the computer system Online – available to the computer system

Interchangeable Disks Floppy disk – 1.44 MB SuperDisk – 120 MB Zip disk – 100,250,700 MB

Interchangeable Disks Disk Density – number of bits that can be stored per unit of area on the disk- face surface

Care of Interchangeable Disks Avoid extreme temperatures Avoid direct sunlight and magnetic fields Only remove disks when drive light is off Never force a disk into a drive Do not touch the surface of the disk

The Hard Disk Read/write head – accesses or places data on the disk Access arms – where the read/write heads are mounted

The Hard Disk Portable hard disk – connects to a computer through a USB or FireWire port

Disk Organization Tracks

Concentric circles on the disk where data is storedTrack density – tracks per inch (TPI)Recording density – megabits per inch

Disk Organization Sectors

Sector organization Sector – pie-shaped areaClusters – adjacent sectors

Disk Organization Disk address – number of the first cluster in a file Cylinder – same-numbered tracks on each recording surface Zone recording – tracks grouped into zones

File Allocation Table Virtual File Allocation Table (VFAT) – keeps track of where each cluster can be found on the disk

Maintaining the Disk ScanDisk – searches the disk for lost clusters Defragmentation – reorganizes the disk

Preparing the Disk for Use Formatting – sets up disk for use on a particular operating system

Creates sectors and tracksCreates an area for the VFAT

Disk Speed Access time – the interval between when a computer makes a request for data to be transferred and when the operation is completed

Disk SpeedData transfer rate – how fast data is transferred from RAM to storage or from storage to RAM Disk caching – using RAM to store some software that will likely be needed

Virtual MemoryOperating system breaks programs into pages. Only pages being used are placed in RAM.

CD-ROMCD (compact disc) – originally used for recording musicCD-ROM (compact disc – read-only memory) – user may read, but can’t change informationCD-ROM holds up to 650 MB

DVD-ROMDVD (digital video disc)Stores 7 to 14 times as much as a CDDVD drives are backward compatible – they will read CDs and CD-ROMs

Rewritable Optical Laser Disc Options

CD-R (compact disc-recordable) – user may record data, but can’t change itCD-RW (compact disc-rewritable) – user may record data and change it as needed

Optical Discs in Your PCDVD-ROM/CD-RW combination driveDVD+RW/CD-RW combination drive – allows for recording of original videos to DVD

Other Storage OptionsFlash memory – low-cost, solid-state memoryMini USB drive

Plugs into a computer’s USB port About the size of your thumb

Input and Output DevicesInput device – converts our commands and data into a form a computer can understand Output device – converts computer data into a form humans can understand

The KeyboardTraditional alphanumeric keyboard

QWERTY

Special-function keyboardFast-food cash registers

The MouseUsed in a GUI (Graphical User Interface)Point and select (click)Mouse pointer – cursor

Other Pointing DevicesTrackpad

Used mostly on notebook computersMove your finger over the touch-sensitive pad

Trackpoint – similar to a miniature joystickTrackball – similar to an upside-down mouse

Other Pointing Devices Joystick – vertical stick used to move the pointer Digitizer tablet and pen – allow for the digitizing of images

Scanners Scanners convert printed matter into a format that can be stored in a computer

Scanners for Source Data Automation Handheld label scanner or wand scanner Stationary label scanner Document scanner

Turnaround document

Bar Code UPC – Universal Product Code

OCR Technology OCR (optical character recognition) – scans characters into a computerMICR (magnetic-ink character recognition) – used in banking industryOMR (optical mark recognition) – used to grade tests or questionnaires

Image Scanners Image scanner – capable of translating text or images into a form a computer can readImage processing – manipulating scanned images

Page and Hand Image Scanners Page image scanner – works like a copy machine Hand image scanner – manually rolled over the image to be scanned

Magnetic StripesMagnetic stripes like the ones on credit cardsBadge reader – device to read an employee’s badge to determine clearance

Smart CardCan store information or money

Speech RecognitionSpeaker-dependent – can interpret spoken words from only one personSpeaker-independent – will accept words from anyone, but has a limited vocabulary

DigicamsDigital camera – records images digitallyDigital video camera – captures motion videoWebcams – digital video cameras connected to the Internet

DigicamsDigital camcorder – captures video digitally Video capture card – expansion card that allows for the capture of video to disk

Handheld and Wearable Data Entry Devices

Limited keyboardSmall touch-sensitive displayStorage capability – probably solid- stateScanning device capable of OCR

MonitorsCRT monitor – takes up a great deal of spaceFlat-panel monitor – found on notebook PCs and some desktops; much smaller than CRT monitors

Flat-Panel MonitorsLCD (liquid crystal display) Active matrix – more brilliant display, also called TFT (thin film transistor)

Passive matrix

MonitorsGraphics adapter – monitor’s device controllerVideo Ram or VRAM – memory on the graphics adapter where images are prepared for display on the monitor

MonitorsDual monitor – high-end graphics adapters, allow for multiple monitors to be connected to one PC

Monitor SizeMeasured diagonally

5 to 60 inches

Monitor ResolutionResolution depends on:

Number of pixels that can be displayedNumber of bits used to represent a pixelDot pitch of the monitor

Monitor ResolutionPixel (picture element) – a dot on the screenGray scales – number of shades of a color that can be displayed

Monitor ResolutionRGB monitor – creates colors by combining red, green, and blueColor depth – number of bits used to represent a pixelDot pitch – distance between the centers of adjacent pixels

MonitorsTouch screen monitor – user indicates choice by touching the screenLCD projector – allows the user to project what is on the computer monitor onto a large screen for an audience

PrintersLaser printer – prints a page at a time Ink-jet printer – ink is sprayed onto paper to form characters and imagesLarge-format ink-jet printer – used to create large documents such as blueprints

PrintersAll-in-one multifunction device – has all of the capabilities of a printer, fax machine, scanner, and copier

SoundSound cardSpeaker system

Voice OutputVoice Response System

Reproduction of a human voiceSpeech synthesis

Speech synthesis system – converts data into electronic speechText-to-speech software – produces speech by combining phenomes

Computers Chapter 5 – Storage and Input/Output

DevicesLesson Summary

• Understand the various types of magnetic disk storage

• Understand the various types of optical laser disc storage

• Understand common input devices• Understand common output

devices

Computers © 2005 Prentice-Hall, Inc.Slide 1. Computers Chapter 5 Storage and Input/Output Devices...

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