1

© Peter Lo 2002 1

HardwareHardware

Part 1: Inside the System Unit

© Peter Lo 2002 2

Computer and PeripheralsComputer and Peripherals

n Computer uRefer only to the Central processing unit

(CPU), the circuitry that processes the data, and the computer’s memory.

n PeripheralsuAll additional hardware components grouped

around the CPU and memory

© Peter Lo 2002 3

Computer Hardware OverviewComputer Hardware Overview

© Peter Lo 2002 4

System UnitSystem UnitnIt is a Box-like case

that contains computer’s electronic components nSometimes called

the Chassis

2

© Peter Lo 2002 5

Exposed System UnitExposed System Unit

© Peter Lo 2002 6

How do computers represent data?How do computers represent data?

nMost computers are digitaln Recognize only two discrete states: on or off

1 1 1 1 1

0 0 0 0 0

on

off

© Peter Lo 2002 7

Binary SystemBinary System

n Number system with two unique digits: 0 and 1Binary

Digit (bit)Electronic

ChargeElectronic

State

© Peter Lo 2002 8

What is a byte?What is a byte?

n Eight bits grouped together is a byte8-bit byte for the number 3

8-bit byte for the number 5

8-bit byte for the capital letter T

3

© Peter Lo 2002 9

Three Popular Coding Systems to Three Popular Coding Systems to Represent DataRepresent Data

° ASCII - American Standard Code for Information Interchange

° EBCDIC - Extended Binary Coded Decimal Interchange Code

° Unicode - coding scheme capable of representing all world’s languages

© Peter Lo 2002 10

How is a Character Sent from How is a Character Sent from Keyboard to Computer?Keyboard to Computer?

Step 2: Electronic signal for letter T sent to system unit

Step 3: Signal changed to its ASCII code (01010100) and stored in memory

Step 4: After processing, binary code for letter T is converted to image on output device

Step 1: Press letter T

© Peter Lo 2002 11

Central Processing Unit (CPU) ?Central Processing Unit (CPU) ?

n Interprets and carries out basic instructions that operate a computer

n Also called the Processor

© Peter Lo 2002 12

Components of the CPUComponents of the CPU

CPU

Arithmetic/Logic Unit

(ALU)

Control Unit

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© Peter Lo 2002 13

Control UnitControl Unit

Control Unit

Control unit repeatsfour basic operations:

° Fetch - obtain program instruction or data item from memory

° Decode - translate instruction into commands

° Execute - carry out command° Store - write result to memory

° Directs and coordinates operations in computer

© Peter Lo 2002 14

Machine Cycle?Machine Cycle?°Four operations of the CPU comprise a machine cycle°Also called instruction cycle

• Execution time (e-time) - time taken to execute and store

e-time

• Instruction time (i-time) - time taken to fetch and decode

i-time

© Peter Lo 2002 15

An example of a machine cycleAn example of a machine cycle

Student enters math problem (100 x 52) into computer’s memory

Result in memory displays on monitor’s screen

100 x 52

© Peter Lo 2002 16

Available CPU PackagesAvailable CPU Packages

dual inline package (DIP)

pin grid array (PGA)

single edge contact (SEC) cartridge

flip chip-PGA(FC-PGA) package

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© Peter Lo 2002 17

CPUCPU’’s speed Measurings speed Measuring

° According to how many millions of instructions per second (MIPS) it can process

© Peter Lo 2002 18

Two Designs used for the CPUTwo Designs used for the CPU

CISC(complex instruction set

computing)° Supports large number

of instructions° CPU executes complex

instructions more quickly

RISC(reduced instruction

set computing)

° Supports smaller number of instructions

° CPU executes simple instructions more quickly

© Peter Lo 2002 19

Arithmetic/Logic unit (ALU) Arithmetic/Logic unit (ALU)

n CPU component that performs execution part of the machine cycle

Comparison (greater than, equal

to, or less than)

Arithmetic(addition, subtraction,

multiplication, and division)

..and.and.

..not.not...or.or.Logical(AND, OR,

NOT)© Peter Lo 2002 20

PipeliningPipeliningn CPU begins executing second instruction before

completing first instruction. Results in faster processing

Machine Cycle (without pipelining)

Machine Cycle (with pipelining)

Instruction 1

Instruction 2

Instruction 3

Instruction 4

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© Peter Lo 2002 21

RegisterRegister

Stores location from where

instruction was fetched

Stores instruction while it is

being decoded

Stores data while ALU processes it

Stores results of calculation

° Temporary storage area that holds data and instructions

© Peter Lo 2002 22

System ClockSystem Clock

n Synchronizes all computer operationsn Each tick is clock cycle

MHz - one million ticks of system clock

GHz – one billion ticks of system clock

© Peter Lo 2002 23

MicroprocessorMicroprocessor

n Single processor chip found in personal computers

© Peter Lo 2002 24

How do personal computer How do personal computer processors compare?processors compare?

7

© Peter Lo 2002 25

CoprocessorCoprocessor

One type is a floating-point coprocessor,

also known as a math or numeric

coprocessor

Chip that assists processor in performing

specific tasks

© Peter Lo 2002 26

Parallel ProcessingParallel Processing°Using multiple processors

simultaneously to execute program faster

°Requires special software to divide problem and bring results together

© Peter Lo 2002 27

Memory: The CPUMemory: The CPU’’s Electronic s Electronic ScratchpadScratchpadnMemory is the temporary storage area for

operating system, application programs, and data n It consists of one or more chips on motherboardn Each byte stored in unique address

© Peter Lo 2002 28

How is memory measured?How is memory measured?

nMemory is measured by number of bytes available

8

© Peter Lo 2002 29

Two types of System Unit MemoryTwo types of System Unit Memory

volatile memoryLoses its contents when Loses its contents when the computer's power is the computer's power is

turned offturned off

volatile memoryLoses its contents when

computer's poweris turned off

nonvolatile memory

Does NOT lose its contents when

computer’s power is turned off

© Peter Lo 2002 30

Random Access Memory (RAM)Random Access Memory (RAM)

nMemory chips that can be read from and written to by processornMost RAM is volatilen The more RAM a computer has, the faster it

operates

memory module

© Peter Lo 2002 31

Two Basic Types of RAM chipsTwo Basic Types of RAM chips

n Dynamic RAM (DRAM)uMost common typeuAlso called main memory

n Static RAM (SRAM)u Used for special applications such as cacheu Faster and more reliable than DRAM chips

© Peter Lo 2002 32

CacheCache

n Helps speed computer processes by storing frequently used instructions and data

n Also called Memory Cache, Cache Store , or RAM Cache

n L1 cache built in processorn L2 and L3 cache not built in

processor n L2 advanced transfer cache most

common

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© Peter Lo 2002 33

ReadRead--Only Memory (ROM)Only Memory (ROM)n Memory chips that contain data, instructions, or

information that is recorded permanently

BIOS(basic input/output system)

Stored on ROM

Sequence of instructions computer follows to load

operating system and other files when you turn on the

computer

ROM is nonvolatile —

Contents not lost when computer is

turned off

Data can only be read;

cannot be modified in

ROM

© Peter Lo 2002 34

Types of ROM Types of ROM

n FirmwareuROM chips manufactured with permanently written

data, instructions, or information

n PROM (Programmable Read-Only Memory)

uBlank ROM on which you can place items permanentlyn EEPROM (Electrically Erasable Programmable Read-Only Memory)

uType of PROM containing microcode programmer can erase

© Peter Lo 2002 35

Flash MemoryFlash Memory

n Nonvolatile memory that can be erased electronically and reprogrammedn Used with handheld computers and digital

cameras, cellular phones, and automobiles

© Peter Lo 2002 36

CMOSCMOS

n CMOS stand for Complementary Metal-Oxide Semiconductor memoryn Stores information about the computer utype of disk drivesukeyboardumonitorucurrent time and date

n Uses battery to retain information when computer is turned off

10

© Peter Lo 2002 37

Memory Access TimeMemory Access Time

n Speed at which processor can access data from memory directly

n Measured in nanoseconds (ns), which is one billionth of a second

n It takes 1/10 of a second to blink your eye; a computer can perform up to 10 million operations in same amount of time

© Peter Lo 2002 38

BUSBUS° Channel that allows devices inside

computer to communicate with each other

° System bus connects processor and RAM

° Bus width determines numberof bits transmitted at one time

° Word size determines numberof bits processor can interpretand execute at a given time

system bus

RAM

processor

© Peter Lo 2002 39

Expansion BusExpansion Busn Allows processor to communicate with peripherals

fastestnext fastestnext fastestslowest

processor

memory

PCI bus expansion slots ISA bus expansion slots © Peter Lo 2002 40

Expansion SlotExpansion Slot

°An opening, or socket, where circuit board is inserted into motherboard

°Expansion card inserted in expansion slot

expansion card

expansion slot

11

© Peter Lo 2002 41

How are expansion cards used?How are expansion cards used?

© Peter Lo 2002 42

Plug and PlayPlug and Play

n Computer automatically can configure cards and other devices as you install them

© Peter Lo 2002 43

PCMCIA cardPCMCIA card

n Credit card-sized device used to add capabilities to notebook computers

n PCMCIA stand for Personal Computer Memory Card International Association

n Uses include modem, additional memory, and storage

© Peter Lo 2002 44

Flash Memory CardFlash Memory Card

n Adds memory to handheld computers, digital music players, cellular telephones, and similar devices

12

© Peter Lo 2002 45

PortPort keyboard

USBUSB

mouse

telephone line in

game port

monitor

svideo out

network

printer (parallel port)

cable TV

speaker

serial port

microphone

telephone line out

FM reception

°Connects external devices to system unit

© Peter Lo 2002 46

Different Types of ConnectorsDifferent Types of Connectors

© Peter Lo 2002 47

Serial PortSerial Portserial transmission of data

DB-9 female connector

byte representation for number 5 (00110101) byte

representation for number 5 (00110101)

DB-9 male connector

byte representation for number 5 (00110101)

°Transmits one bit of data at a time°Used to connect

slow-speed devices, such as mouse, keyboard, modem

© Peter Lo 2002 48

Parallel PortParallel Portbyte representation for number 1byte representation for number 3

byte representation fornumber 5

DB-25 male connector

DB-25 female connector

°Connects devices that can transfer more than one bit at a time, such as a printer

13

© Peter Lo 2002 49

Universal Serial Bus port (USB) Universal Serial Bus port (USB)

n Connector that supports newer peripherals and plug and play

n Other popular ports include 1394, MIDI, SCSI, and IrDA

USB port

1394 port

© Peter Lo 2002 50

BayBayDVD-ROM drive

CD-RW drive

Zip drive

empty drive bay

floppy disk drive

n Open area inside system unit usedto install additional equipment

© Peter Lo 2002 51

Power SupplyPower Supply

n Converts alternating current (AC) to direct current (DC)n Some peripheral devices have AC adapter

© Peter Lo 2002 52

What ports are on a notebook What ports are on a notebook computer?computer?

keyboard/mouse port

IrDA port

serial port

parallel port video port

USB port

14

© Peter Lo 2002 53

How is data transferred from a How is data transferred from a handheld computer?handheld computer?n An IrDA port allows the handheld computer to

communicate wirelessly with other computers or devicesn Handheld computers also can rest in a cradle, so you can

transfer data to your desktop computer

IrDA port

cradle

© Peter Lo 2002 54

HardwareHardware

Part 2: Data Storage

© Peter Lo 2002 55

What is storage?What is storage?

nMedia and devices used to store and retrieve data, instructions, and information

© Peter Lo 2002 56

How does storage differ from How does storage differ from memory?memory?

When you want to work

with a file, you read it

from storage and place it in

memory

When you are finished with the file, you write it from memory into

storage

n Stores items for future use, rather than temporarily

n Storage is nonvolatile, rather than volatile

15

© Peter Lo 2002 57

How does volatility compare?How does volatility compare?

Contents of storage retained when power is off

Contents of storage retained when power is off

Screen display and contents of most RAM (memory) erased when power is off

Screen display and contents of most RAM (memory) erased when power is off

© Peter Lo 2002 58

What is a storage device and a What is a storage device and a storage Medium?storage Medium?

storage medium

Physical material on which a computer

keeps data, instructions, and

information

storage device

Hardware that records and retrieves items to

and from a storage medium

© Peter Lo 2002 59

readingProcess of transferring data,

instructions, and information from a storage medium into

memory

Serves as a sourceof input

writingProcess of

transferring items from memory to a storage medium

Serves as a source of output

Reading and WritingReading and Writing

© Peter Lo 2002 60

What is access time?What is access time?

Memory (RAM)

Compact Disc

Floppy Disk

Tape

Hard Diskcost

less

exp

ensi

ve

mor

e ex

pens

ive

speed

faster

slower

n Amount of time it takes device to locate item on disk

n Defines speed of disk storage device

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© Peter Lo 2002 61

What is capacity?What is capacity?n Capacity is the

number of bytes (characters) storage medium can hold

Storage Term

Number of bytes

Kilobyte

Megabyte

Gigabyte

Terabyte

Petabyte

KB

MB

TB

GB

PB

1 thousand

1 million

1 billion

1 trillion

1 quadrillion

Abbreviation

© Peter Lo 2002 62

Memory vs. Storage (Summary)Memory vs. Storage (Summary)

LowestVery SlowBackup Tape

LowSlowCD-ROM Disc

MediumMediumHard diskStorage

HighFastRAM

HighestFastestCache MemoryMemory

Cost per MBAccess SpeedDevice

© Peter Lo 2002 63

Floppy DiskFloppy Disk

n Portable, inexpensive storage mediumn Today’s standard disk is 3.5” wide

© Peter Lo 2002 64

What are the parts of a floppy disk?What are the parts of a floppy disk?n Thin, circular,

flexible film enclosed between two liners

shell

shutter

liner

magnetic coating

flexible thin film

metal hub

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© Peter Lo 2002 65

How are floppy disk drives How are floppy disk drives designated?designated?

Two floppy drives

drive A

drive B

One floppy drive

drive A

© Peter Lo 2002 66

How does a floppy disk drive work?How does a floppy disk drive work?

6: Read/write heads read data from or write data on the floppy disk

Step 65: Motor positions read/write heads over correct location on disk

Step 5

4: Motor causes floppy disk to spin

Step 4

3: If write instruction, circuit board verifies whether disk can be written to

Step 3

2: Signal sent to control movement of read/write heads and disk

Step 2

1: Shutter moves to expose recording surface on disk

Step 1

© Peter Lo 2002 67

Tracks and SectorsTracks and Sectorsn Track is narrow

recording band that forms full circle on disk surface

n Sector can store up to 512 bytes of data

sector18 per track

track80 per

side

80 tracks per side x 18 sectors per track x 2 sides per disk x 512 bytes per sector = 1,474,560 bytes © Peter Lo 2002 68

Format (for Disk)Format (for Disk)n Process of preparing disk for

reading and writing

n Formatting marks bad sectors as unusable

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© Peter Lo 2002 69

How to take care a floppy?How to take care a floppy?

n Proper care helps maximize disk’s life n Floppy disk can last at least seven years

© Peter Lo 2002 70

What is a writeWhat is a write--protect notch?protect notch?

write-protected

not write-protected

n Small opening with a cover that you slide

n Protects floppy disks from being erased accidentally

notch closed means you

can write on the disk

notch closed means you

can write on the disk

notch open means you cannot write on the disk

notch open means you cannot write on the disk

© Peter Lo 2002 71

HighHigh--capacity Disk Drivecapacity Disk Drive

n Uses disks with capacities of 100 MB and greatern Primarily used to backup files and transfer files

© Peter Lo 2002 72

Hard DiskHard Disk

n High-capacity storagen Consists of several inflexible, circular platters that store

items electronically

n Components enclosed in airtight, sealed case for protection

hard disk installed in system unit

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© Peter Lo 2002 73

How does a hard disk work?How does a hard disk work?

4: Head actuator positions read/write head arms over correct location on platters to read or write data

Step 4

2: Small motor spins platters

Step 2

3: When software requests disk access, read/write heads determine location of data

Step 3

1: Circuit board controls movement of head activator and small motor

Step 1

© Peter Lo 2002 74

What is a Cylinder?What is a Cylinder?

n Location of a single track through all plattersn Single movement of

read/write head arms can read same track on all platters

trackcylinder

© Peter Lo 2002 75

A head crash!A head crash!

n Occurs when read/write head touches platter surfacen Spinning creates cushion of air that floats read/write head

above platter

hair

read/write head

dustsmoke

platter

gap

clearance between head and platter is approximately two millionths

of an inch

clearance between head and platter is approximately two millionths

of an inch

gap is half the diameter of a dust particle

gap is half the diameter of a dust particle

© Peter Lo 2002 76

Disk CacheDisk Cache

n Portion of memory processor uses to store frequently accessed items

processor

hard disk

disk cache

processor

hard disk

disk cache

first request for data — to disk cache

processor

hard disk

disk cache

second request for data — to hard disk

first request for data — to disk cache

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© Peter Lo 2002 77

What is a Partition?What is a Partition?n Formatted hard disk

divided into separate areas called partitionsn Each partition

functions as if it were a separate hard disk drive

drive CDesignation for first

partition or for a single partition on hard disk

drive DDesignation for second partition on hard disk

one hard disk divided into

two partitions

© Peter Lo 2002 78

Removable Hard Disk?Removable Hard Disk?

n Disk drive in which a plastic or metal case surrounds the hard disk so you can remove it from the driven Used for backup or to transfer files

© Peter Lo 2002 79

How does RAID work?How does RAID work?

n Disk system that duplicates data, instructions, and information to improve data reliabilityuMirroring has one backup disk for each disk

uStriping stores data across multiple disks

mirroring(RAID Level 1)

striping

© Peter Lo 2002 80

What Windows Utilities Maintain What Windows Utilities Maintain a Hard Disk Drive?a Hard Disk Drive?

System Tools

21

© Peter Lo 2002 81

Internet Hard Drive?Internet Hard Drive?

n Service on Web that provides storage to computer usersn Most offer free storagen Revenues come from advertisers

© Peter Lo 2002 82

Advantages of Internet hard driveAdvantages of Internet hard drive

Allows offsite backups of data

Others can be authorized to access

data from your Internet hard drive

Files can be accessed from any computer or device

with Web access

Large audio, video, and graphics files can be downloaded to an

Internet hard drive instantaneously

© Peter Lo 2002 83

Compact Disc (CD)Compact Disc (CD)

n Storage medium nMost PCs include some type of compact disc driven Available in variety of formats

CD-ROM

CD-R

CD-RW

DVD-ROM

DVD+RW

© Peter Lo 2002 84

How do you use a compact disc?How do you use a compact disc?n CD drives can read

compact discs, including audio discs

Push button to slide out

the tray

Push button to slide out

the tray

Insert disc, label side upInsert disc,

label side up

Push the same button to close

the tray

Push the same button to close

the tray

22

© Peter Lo 2002 85

How does a laser read data on a How does a laser read data on a compact disc?compact disc?

3: Reflected light deflected to light- sensing diode, which sends digital signal of 1. Absence of reflected light read as digital signal of 0.

1: Laser diode shines light beam toward compact disc

2: If light strikes pit, it scatters. If light strikes land, it is reflected back toward laser diode.

Compact disc label

Compact disc label

lens lens

prism prism

laser diode

laser diode

Step 1Compact disc

label

lens lens

prism prism

laser diode

laser diode

Step 2Compact disc

label

lens lens

prism prism

laser diode

laser diode

pit land

Step 3Compact disc

label

lens lens

prism prism

laser diode

laser diode

Light-sensing

diode

Light-sensing

diode

0 1

pit land

© Peter Lo 2002 86

How data stored on a compact disc?How data stored on a compact disc?

n Typically stores items in single trackn Track divided into evenly sized sectors that store items

Compact disc sectors

Single track spirals to edge of disc

© Peter Lo 2002 87

What is a jewel box?What is a jewel box?

n Protective case for compact disc

jewel box

© Peter Lo 2002 88

How should you care for a How should you care for a compact disc?compact disc?

1: Do not expose to excessive heat or sunlight

2: Do not eat, smoke, or drink near a disc

3: Do not stack

4: Do not touch underside

5: Store in jewel box when not in use

6: Hold disc by its edges

23

© Peter Lo 2002 89

What is a CDWhat is a CD--ROM?ROM?

n Compact disc that uses same laser technology as audio CDs for recording music

n Cannot erase or modify contents

n Typical CD-ROM holds about 650 MBn Commonly used to distribute software and games

© Peter Lo 2002 90

CDCD--R (Compact DiscR (Compact Disc--RecordableRecordable))

n Compact disc onto which you can record text, graphics, and audio

n Write on CD-R using CD burner (recorder) or CD-R drive and special software

n CD-R drive can read and write both audio CDs and standard CD-ROMs

n Cannot erase disc’s contents

© Peter Lo 2002 91

CDCD--RW (compact discRW (compact disc--rewritablerewritable))

n Erasable disc you can write on Multiple TimesnMust have a CD-RW disc, CD-RW software,

and CD-RW drive

© Peter Lo 2002 92

How to Create Audio CD?How to Create Audio CD?

Step 5: User listens to song on personal computer or removes CD and listens to song on portable CD player

11

2a 2b

1

2a 2b

3a 3b

1

2a 2b

3a 3b

4

Step 2a: Song stored on audio CD and purchased by user

OR

Step 2b: Song compressed and stored on Internet

Step 3a: User inserts audio CD into CD-ROM drive, plays song, and copies it to hard disk

OR

Step 3b: User downloads song as audio file to hard disk

Step 1: Artist composes song and creates CD

Step 4: User copies file to CD-RW disc

1

2a 2b

3a 3b

4

5

24

© Peter Lo 2002 93

DVDDVD--ROM (Digital Video DiscROM (Digital Video Disc--ROM)ROM)n High capacity compact disc capable of storing

from 4.7 GB to 17 GBnMust have DVD -ROM drive or DVD player to

read DVD-ROMn Primarily used for moviesn Next-generation software will be delivered on

DVD

© Peter Lo 2002 94

How does a DVDHow does a DVD--ROM store data?ROM store data?

n Two layers of pits are used, where lower layer is semitransparentn Laser can read through it to upper layern DVD+RW is a rewritable DVD

© Peter Lo 2002 95

TapeTape

n Magnetically coated ribbon of plastic capable of storing large amounts of data and information at a low cost

n Primarily used for backup

© Peter Lo 2002 96

Sequential Access vs. Direct AccessSequential Access vs. Direct Access

n Sequential AccessuReading and writing data consecutively uMethod used for tape

n Direct AccessuCan locate a particular data item or file

immediately uMethod used for floppy disks, hard disks, and

compact discs uAlso called Random Access

25

© Peter Lo 2002 97

Enterprise Storage SystemEnterprise Storage System

Network Storage Internet backupNetwork StorageNetwork Storage

CD-ROM jukeboxes

Internet backup

tape library

Network Storage

CD-ROM jukeboxes

Internet backup

RAID

Storage area network

servers

tape library

Network storage

CD-ROM jukeboxes

Internet backup

n Strategy that focuses on availability, protection , organization, and backup of storage in a company

© Peter Lo 2002 98

Miniature Mobile Storage MediaMiniature Mobile Storage Media

n Handheld devices use to augment internal storage

CompactFlash

Memory Stick

Microdrive

SmartMedia

40 MB

2 to 256 MB

1 GB

2 to 128 MB

CartridgeDigital cameras, notebook computers

Memory CardDigital cameras, handheld computers, notebook computers, printers, cellular telephones

Memory CardDigital cameras, handheld computers, music players, video cameras

Memory CardDigital cameras, handheld computers, photo printers, cellular telephones

© Peter Lo 2002 99

Smart CardSmart Card

n Stores data on thin microprocessor embedded in credit card

smart card

© Peter Lo 2002 100

Types of smart cardsTypes of smart cardsStore data such as

photographs, music, books, and video clips

n Intelligent smart card contains processor and has input, process, output, and storage capabilities

n Memory card has only storage capabilities

Store a prepaid dollar amount that is updated when the card is

used

Store patient records, vaccination data, and other

healthcare information

Store tracking information such as customer purchases or

employee attendance

26

© Peter Lo 2002 101

Electronic MoneyElectronic Moneyn Means of paying for

goods and services over the Internet

n Also callede-money or digital cash

Bank issues unique digital cash numbers

that represent an amount of money

When you purchase digital cash, the amount

of money is withdrawn from

your bank account

To use the card, swipe it through

a card reader

© Peter Lo 2002 102

Microfilm and MicroficheMicrofilm and Microfichen Store microscopic images of

documents on a roll or a sheet of filmn Images recorded using a computer

output microfilm (COM) recorder

MicroficheUses a small sheet

of film, usually4” x 6”

MicrofilmUses a 100- to 215-

foot roll of film

© Peter Lo 2002 103

Life expectancies of various mediaLife expectancies of various media

© Peter Lo 2002 104

What is a backup?What is a backup?n Duplicate of file, program, or

disk that you can use if original is lost, damaged, or destroyed

data

instructions

information

27

© Peter Lo 2002 105

HardwareHardware

Part 3: Input and Output

© Peter Lo 2002 106

What is input?What is input?

n Data

uUnprocessed facts, figures, and symbols

n InstructionsuProgramsuCommands

uUser responses

DATA Susan works 42 hours at $300/hr

hard disk

COMMANDS

print the

timeca

rd

PROGRAMS

timeca

rd

USER RESPONSES

Yes, the tim

ecard entries

are correc

t

No, the tim

ecard e

ntries ar

e not co

rrect

INSTRUCTIONS

© Peter Lo 2002 107

What is an input device?What is an input device?

n Any hardware component used to enter data, programs, commands, and user responses into a computer

scanners and reading devices

voice inputkeyboard

pointing device

video input

digital camera © Peter Lo 2002 108

How is the keyboard divided?How is the keyboard divided?

n Typing arean Numeric keypadn Function keys

numeric keypad

typing area

function keys

28

© Peter Lo 2002 109

Portable KeyboardPortable Keyboard

n Full-sized keyboard you conveniently can attach and remove from a handheld computer

© Peter Lo 2002 110

Ergonomic KeyboardErgonomic Keyboard

n Designed to minimize strain on hands and wristsn Ergonomics incorporates comfort, efficiency, and

safety into design of items in workplace

© Peter Lo 2002 111

Alternative forms for commandsAlternative forms for commands

nMany programs allow you to use button, menu, or function key to obtain same result

Command Button Menu Function Key(s)

Copy Edit|Copy SHIFT+F2

Open File|Open CTRL+F12

Print File|Print CTRL+SHIFT+F12

© Peter Lo 2002 112

MouseMouse

n Pointing device that fits under palm of handn Controls movement of pointer, also called mouse

pointer, on screenn Pointer on screen takes several shapes

I-beam block arrow pointing hand

29

© Peter Lo 2002 113

How does mechanical mouse work?How does mechanical mouse work?n Rubber or metal ball is

on its undersiden Movement of mouse

translates into signals computer understands

mouse padmouse pad

ballball

wheel buttonwheel button

mousebuttonsmouse

buttons

© Peter Lo 2002 114

How does an optical mouse work?How does an optical mouse work?n Senses light to detect

mouse’s movementn More precise than

mechanical mousen Connect using a cable or

wireless

back buttonback

button

wheel buttonwheel button

forward button

forward button

optical sensor

optical sensor

© Peter Lo 2002 115

Common mouse operationsCommon mouse operations

n Pointn Clickn Right-clickn Double-clickn Dragn Right-dragn Rotate wheeln Press wheel

© Peter Lo 2002 116

TrackballTrackball

n Stationary pointing device with a ball on its topn To move pointer, rotate ball with thumb, fingers,

or palm of hand

trackball

30

© Peter Lo 2002 117

TouchpadTouchpad

n Small, flat, rectangular pointing device sensitive to pressure and motion

touchpad

© Peter Lo 2002 118

Pointing StickPointing Stick

n Pointing device shaped like pencil eraser positioned between keys on keyboard

pointing stick

© Peter Lo 2002 119

Joystick and WheelJoystick and Wheel

n Joystick is vertical lever mounted on a basen Wheel is steering-wheel type input devicen Pedal simulates car brakes and accelerator

joystick

pedal

wheel

© Peter Lo 2002 120

Light PenLight Pen

n Handheld input device that contains light source or can detect light

n Press light pen against screen surface and then press button on pen

light pen

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© Peter Lo 2002 121

Touch ScreenTouch Screen

n Touch areas of screen with fingern Often used with kiosks

touch screen

© Peter Lo 2002 122

StylusStylus

n Looks like a ballpoint pen, but uses pressure to write text and draw lines

n Used with graphics tablets and handheld computers

stylus or pen

© Peter Lo 2002 123

Electronic SignatureElectronic Signature

n Pen and graphics tablet used with special software for handwriting recognition

n Legal as ink signature

n Also called e-signature

© Peter Lo 2002 124

Handwriting RecognitionHandwriting Recognition

n Translates handwritten letters and symbols into characters that the computer can understand

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© Peter Lo 2002 125

How does voice recognition work? How does voice recognition work?

You’re right!

Step 1: Dictate

… Your write… You’re right… Your right

Natural Language Engine

your, you’re

right, writeMatches

Step 2: Convert analog to digital

Step 3: Check database for match

Step 4: Most likely match selected

© Peter Lo 2002 126

MIDI (Musical Instrument Digital MIDI (Musical Instrument Digital Interface)Interface)n External device, such as electronic piano keyboard,

to input music and sound effects

© Peter Lo 2002 127

How is a data entered into a How is a data entered into a handheld device?handheld device?

transfer data from desktop computer

digital camera

stylus

voice input

portable keyboard

stylus

handwriting recognition characters

stylus

on-screen keyboard

© Peter Lo 2002 128

Digital CameraDigital Camera

n Allows you to take digital pictures n Images viewable immediately on cameran Download to computern Post pictures to Web

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© Peter Lo 2002 129

How does a digital camera work? How does a digital camera work?

7: View and manipulate image

2: Image focuses on CCD

3: CCD generates analog signal that represents image

1: Take picture

4: Analog signalconverts to digital signal

5: Digital signal processor (DSP) adjusts quality

Step 1Step 1

Step 2

Step 3

Step 1

Step 2

Step 4

Step 3

Step 1

Step 2

Step 5

Step 4

Step 3

Step 1

Step 2

Step 5

Step 4

Step 3

Step 1

Step 2

Step 6

Step 5

Step 4

Step 3

Step 1

Step 2

Step 7

6: Transfer image to computer

© Peter Lo 2002 130

ResolutionResolution

n Sharpness and clarity of imagen Higher the resolution, the better the image quality,

but the more expensive the cameran Pixel (picture element) is single point in electronic

imagen Greater the number of pixels, the better the image

quality

© Peter Lo 2002 131

Video InputVideo Input

n Process of entering full-motion recording into computer n Also called Video Capturen Video capture card is expansion card that converts analog

video signal into digital signalthat computer understands

n Video compression

analog video camera

analog video camera

digital video camera

digital video camera

© Peter Lo 2002 132

PC Video CameraPC Video Camera

n Digital video camera that allows home user to record, edit, and capture video and still images, and to make video telephone calls on Internet

n Also called PC Camera

PC video camera

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© Peter Lo 2002 133

Web CamWeb Cam

n Video camera whose output displays on a Web pagen Also called a camn Streaming cam shows moving images by sending continual

stream of pictures

Web cam video output

© Peter Lo 2002 134

VideoconferencingVideoconferencing

n Two or more geographically separated people who use network on the Internet to transmit audio and video data

n Whiteboard is another window on screen that can display notes and drawings simultaneously on all participants’screens

© Peter Lo 2002 135

ScannerScanner

n Device that captures data directly from source documentuSource document is original form of data

OCR

flatbed scanner © Peter Lo 2002 136

How does a flatbed scanner work?How does a flatbed scanner work?

Step 1

Step 2

Step 1

Step 2

Step 3

Step 1

Step 2

Step 3

Step 4

Step 1

Step 2

Step 3

Step 4

Step 5

2: Bright light scans document

3: Image reflected into mirrors4: Light converted to analog electrical and then to digital signal

5: Digital information sent to computer

6: Print or save document

Step 6

1: Place document face down

Step 1

35

© Peter Lo 2002 137

Various types of scannersVarious types of scanners

Drum

Pen or handheld

Sheet-fed

Flatbed

© Peter Lo 2002 138

Image ProcessingImage Processing

n Capturing, storing, analyzing, displaying, printing, and manipulating imagesn Converting paper documents

into electronic formn Also called Imaging

© Peter Lo 2002 139

Optical ReaderOptical Reader

n Device that uses light source to read characters, marks, and codes and then converts them into digital datauOptical character recognition (OCR)uOptical mark recognition (OMR)uBar code scanner

© Peter Lo 2002 140

OCR FontOCR Font

n OCR font, such as OCR-A, used with OCR devicesn OCR device determines characters’shapes by

detecting patterns of light and darkn OCR software converts shapes into characters the

computer can understand

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© Peter Lo 2002 141

Turnaround DocumentTurnaround Documentn You return it to

company that sent it

numbers are read by OCR device when document is returned

© Peter Lo 2002 142

Optical Mark Recognition (OMR)Optical Mark Recognition (OMR)

n Reads hand-drawn pencil marks, such as small circles or rectangles

© Peter Lo 2002 143

Bar Code ScannerBar Code Scanner

n Uses laser beams to read bar codes

bar code scanners

© Peter Lo 2002 144

Bar CodeBar Code

n Identification code that consists of a set of vertical lines and spaces of different widths

n Universal Product Code (UPC)

Number system character identifies type of product

Number system character identifies type of product

Manufacturer identification number

(Kellogg’s, in this case)

Manufacturer identification number

(Kellogg’s, in this case)

Check character verifies accuracy of scanned

UPC symbol

Check character verifies accuracy of scanned

UPC symbol

Item number (10 oz. box of Froot Loops

Item number (10 oz. box of Froot Loops

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© Peter Lo 2002 145

Magnetic Ink Character Magnetic Ink Character Recognition Reader (MICR)Recognition Reader (MICR)n Can read text printed with magnetized inkn Banking industry almost exclusively uses MICR for check

processing

check number

bank number

check amount

account number

© Peter Lo 2002 146

Wireless InputWireless Input

n Handheld computer or device used to collect data wirelessly at the location where transaction or event takes place

n Data transferred later to desktop computer through docking station

© Peter Lo 2002 147

Input Devices for Physically Input Devices for Physically Challenged UsersChallenged Users

speech recognition

onscreen keyboard

pointing device for those with motor disabilities

keyguard for limited hand mobility

© Peter Lo 2002 148

New developments for physically New developments for physically challenged userschallenged usersn Gesture recognitionuComputer will detect human motionsuComputers with this capability have potential to

recognize sign language, read lips, track facial movements, or follow eye gazes

n ImplantationuFor paralyzed or speech- impaired individualsuDoctor will implant computerized device containing

transmitter into brainuAs user thinks, transmitter will send signals to

computer

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© Peter Lo 2002 149

What Is output?What Is output?

video

audio

textgraphics

n Data that has been processed into a useful form, called information

© Peter Lo 2002 150

Output DeviceOutput Device

n Any hardware component that can convey information to a user

printer

monitor speakers

© Peter Lo 2002 151

Display DeviceDisplay Device

n Television-liken Information on a display device sometimes is

called Soft Copy

© Peter Lo 2002 152

CRT MonitorCRT Monitor

n Large sealed, glass screen

n Screen coated with tiny dots of phosphor material

n Pixel, or picture element, is single point in electronic image

n Three dots (red, blue, and green) combine to make up each pixel

CRT monitor screen

cathode ray tube

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© Peter Lo 2002 153

Typical sizes for CRT monitorsTypical sizes for CRT monitors

n 15, 17, 19, 21, and 22 inch screen sizen Viewable size is

diagonal measurement of actual viewing area provided by the monitor

screen

size

viewab

le size

© Peter Lo 2002 154

Liquid Crystal Display (LCD)Liquid Crystal Display (LCD)

n Type of flat-panel displayn Uses liquid crystals between two sheets of

material to present information on screenn Electric current passes through crystals, which

creates images on the screen

© Peter Lo 2002 155

Some features of LCD screensSome features of LCD screens

n Lightweight and compactn Consumes less than one-

third of the power than does a CRT monitorn Ideal for notebook and

handheld computers

© Peter Lo 2002 156

WebWeb--enabled deviceenabled device

n Allows access to the Web or e-mailuCellular telephonesuPagers

nMany use monochrome LCD displays to save battery power

40

© Peter Lo 2002 157

Electronic Book (eElectronic Book (e--book) book)

n Small, book-sized computer that uses an LCD screenn Allows users to read, save, highlight, bookmark, and add

notes to online text

n Download new book contentfrom Web

© Peter Lo 2002 158

Two technologies used for LCD Two technologies used for LCD monitorsmonitorsn Active-matrix displayuCan display high-quality color viewable from

all anglesn Passive-matrix displayuColor often not as brightuImages best viewed when working directly in

front of display

© Peter Lo 2002 159

Gas Plasma MonitorGas Plasma Monitor

n Flat-panel display uses layer of gas plasma between two sheets of materialn Larger screen sizes and higher display quality than

LCD, but much more expensive

© Peter Lo 2002 160

Display resolutionDisplay resolution

n Describes the sharpness and clarity of imagen The higher the resolution, the sharper the image and the

more that can display on the monitor

800 x 600most common

1280 x 1024maximum resolution

of most monitors

800 horizontal pixels

600 vertical pixels

Total of 480,000 pixels on screen2048 x 1536

maximum for high-end monitors

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© Peter Lo 2002 161

Dot PitchDot Pitch

nMeasure of the distance between pixels n Sometimes called Pixel Pitchn Smaller the distance between the pixels, the

sharper the imagen Use a monitor with a dot pitch of 0.29 millimeters

or lower to minimize eye fatigue

© Peter Lo 2002 162

Refresh RateRefresh Rate

n Speed at which monitor redraws images on the screenn Should be fast enough to maintain a constant,

flicker-free imagen High-quality monitor will provide refresh rate of

at least 75 hertzn Image on the screen redraws itself 75 times per

second

© Peter Lo 2002 163

Video CardVideo Card

n Converts digital output from computer into analog video signaln Controls how display device produces picturen Also called Graphics Cardor Video Adapter

© Peter Lo 2002 164

How does video travel from the How does video travel from the processor to a CRT monitor?processor to a CRT monitor?

Step 1Step 1Step 2

Step 1Step 2

Step 3

Step 1Step 2

Step 4

Step 3

Step 1Step 2

Step 3

Step 4

Step 5

Step 2

Step 3

Step 4

Step 5Step 6

Step 11: Processor sends digital data to video card

2: Video card converts digital data to analog signal3: Analog signal sent via cable to CRT monitor4: CRT separates signal into red, green, and blue signals

5: Electron guns fire color signals to front of CRT

6: Image displays

42

© Peter Lo 2002 165

Bit DepthBit Depth

24-bit video card

Uses 24 bits to store information about each pixel

Can display 16.7 million colors

224 = 16.7 million

colors

n Number of bits a video card uses to store information about each pixel

n Also called Color Depthn Determines number

of colors a video card can display

n Greater the numberof bits, better the resulting image

8-bit video card

Uses 8 bits to store information about

each pixel

Can display 256 different colors

28 =2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 =

256 colors

© Peter Lo 2002 166

What are video standardsWhat are video standards

n Video Electronics Standards Association (VESA) develops video standards

© Peter Lo 2002 167

What are various video card What are various video card configurations?configurations?

© Peter Lo 2002 168

Electromagnetic Radiation (EMR)Electromagnetic Radiation (EMR)

nMagnetic field that travels atspeed of lightn Small amount produced by all CRT monitors

Sit at arm’s length from

CRTEMR is greatest

on sides and back of CRT

monitor

LCD monitors do not pose

this risk

43

© Peter Lo 2002 169

ENERGY STARENERGY STAR®® ProgramProgram

n Program to encourage manufacturers to create energy-efficient devices that require little power when not in usenMonitors and devices meeting guidelines display

ENERGY STAR® label

© Peter Lo 2002 170

Interactive TVInteractive TV

n Two-way communications technology in which users interact with television programmingn HDTV works directly with interactive TV

Select a movie from

a central library of movies

Play games

Bank

ShopVote or respond to

network questionnaires

© Peter Lo 2002 171

PrinterPrinter

n Output device that produces text and graphics on papern Result is hard copy, or printout n Two orientations

portrait orientation

portrait orientation

landscape orientation

landscape orientation © Peter Lo 2002 172

Impact PrinterImpact Printer

n Forms characters by striking a mechanism against ink ribbon that physically contacts paper

n Ideal for printing multipart forms

n Can withstand dusty environments, vibrations, and extreme temperatures

44

© Peter Lo 2002 173

DotDot--matrix Printermatrix Printer

n Impact printer that produces printed images when tiny wire pins on print head mechanism strike inked ribbon

n Most use continuous-form paper

continuous-form paper

© Peter Lo 2002 174

How does dotHow does dot--matrix printer work?matrix printer work?

n When ribbon presses against paper, it creates dots that form characters and graphics

n A higher number of pins (9 to 24) means printer prints more dots per character, which results in higher print quality

dots form characters

© Peter Lo 2002 175

Line PrinterLine Printer

n High-speed impact printer that prints entire line at a time

n Speed measured by number of lines per minute (lpm) it can print

n Band printer prints fully-formed characters using a hammer mechanism

n Shuttle-matrix printer is high-speed printer that works more like a dot-matrix printer

© Peter Lo 2002 176

NonNon--impact printerimpact printer

n Forms characters and graphics on piece of paper without actually striking paper

ink-jet printerthermal printer

laser printer

45

© Peter Lo 2002 177

InkInk--jet Printerjet Printer

n Non-impact printer forms characters and graphics by spraying tiny drops of liquid ink onto piece of papernMost popular type of color printer for home use

© Peter Lo 2002 178

Resolution of a printerResolution of a printer

n Sharpness and clarity of charactersn Measured by number of dots per inch (dpi)

printer can output

300 dpi

1,200 dpi600 dpi

© Peter Lo 2002 179

How does an inkHow does an ink--jet printer work?jet printer work?

4: As vapor bubble collapses, fresh ink is drawn into firing chamber

firing chamber

ink dot

2: Vapor bubble forces ink through nozzle

nozzleink

1: Small resistor heats ink, causing ink to boil and form vapor bubble

bubble

resistor

Print cartridge

nozzleprint head

3: Ink drops onto paper

paper© Peter Lo 2002 180

Laser PrinterLaser Printer

n High-speed, high-quality non-impact printern Prints text and graphics in very high-quality resolution,

ranging from 600 to 1,200 dpi

n Typically costs more than ink-jet printer, but is much faster

46

© Peter Lo 2002 181

How does a laser printer work?How does a laser printer work?

drum

rotating mirror

drum

rotating mirror

drum

rotating mirror

drum

rollers

rotating mirror

drum

1: Drum rotates as paper is fed through2: Mirror deflects laser beam across surface of drum

3: Laser beam creates charge that causes toner to stick to drum4: As drum rotates, toner transfers from drum to paper5: Rollers use heat and pressure to fuse toner to paper

© Peter Lo 2002 182

Thermal PrinterThermal Printer

n Generates images by pushing electrically heated pins against heat-sensitive papern Ideal for small devices, such as adding machines

© Peter Lo 2002 183

Photo PrinterPhoto Printer

n Color printer that produces photo lab quality pictures and prints everyday documents

Select image to print, number of copies, and

size of print

© Peter Lo 2002 184

Label PrinterLabel Printer

n Small printer that prints on adhesive type material that can be placed on a variety of itemsnMost also print bar codes and e-stamps

47

© Peter Lo 2002 185

Portable PrinterPortable Printer

n Small, lightweight ink-jet or thermal printer that allows mobile user to print from notebook or handheld computer while traveling

© Peter Lo 2002 186

PlotterPlotter

n Sophisticated printer used to produce high-quality drawings

n Large-format printer similar to plotter and is used to print quality color prints

plotterlarge-format printer

© Peter Lo 2002 187

Audio Output DeviceAudio Output Device

n Computer component that produces music, speech, and other soundsn Speakers and headsets are common devices

woofer

speakers

© Peter Lo 2002 188

Voice OutputVoice Output

n Computer talks to you through speakers on computer RealPlayer

link to audio broadcast

48

© Peter Lo 2002 189

Internet TelephonyInternet Telephony

n Allows you to have a conversation over the Web, just as if you were talking on the telephone

© Peter Lo 2002 190

Data ProjectorData Projector

n Device that takes image from a computer screen and projects it onto a larger screen

data projector

© Peter Lo 2002 191

Facsimile (fax) MachineFacsimile (fax) Machine

n Device that transmits and receives documents over telephone lines

fax machine

© Peter Lo 2002 192

Fax ModemFax Modem

nModem that allows you to send and receive electronic documents as faxes

external fax modem

external fax modem

internal fax

modem card in system

unit

internal fax

modem card in system

unit

49

© Peter Lo 2002 193

Multifunction Device (MFD) Multifunction Device (MFD)

n Provides the functionality of a printer, scanner, copy machine, and fax machine

all in one

© Peter Lo 2002 194

TerminalTerminal

n Device that performs both input and output

special-purpose terminals

intelligent terminals

dumb terminals

© Peter Lo 2002 195

Dumb TerminalDumb Terminal

n Has a keyboard and monitor, but no processor or memoryn Connects to host

computer that performs processing and then sends output back

keyboard and monitor

© Peter Lo 2002 196

Intelligent TerminalIntelligent Terminalhost computer

intelligent terminal

n Has monitor, keyboard, memory and processor

n Similar to a PC in that it can perform tasks independent of host computer

n Programmable

50

© Peter Lo 2002 197

PointPoint--ofof--Sale (POS) terminalSale (POS) terminal

n Records purchases at point where purchase is made

n Output from POS terminals serves as input to hostcomputer

POS terminal in a grocery store

scanner and keyboard are input© Peter Lo 2002 198

Automated Teller Machine (ATM)Automated Teller Machine (ATM)

n Self-service banking machine that connects to host computer through telephone network

© Peter Lo 2002 199

What is the Magnifier command?What is the Magnifier command?

nWindows Magnifier command enlarges text and other items in window on screen

Location of mouse pointer magnified at top of screen

Location of mouse pointer magnified at top of screen

Magnifier command

Magnifier command

© Peter Lo 2002 200

Other output options for visually Other output options for visually impaired users?impaired users?n Change Window’s settings such as increasing size or

changing color of text to make words easier to readn Blind users can work with voice output

n Braille printer outputs information in Braille onto paper

Braille printer

51

© Peter Lo 2002 201

ReferencesReferences

n Computers in Your Future (Ch. 2)n Introduction to Computing (Ch. 3)n Discovering Computers World 2003 (Ch. 4 – 7)