Hardware Computer and Peripherals Computer Hardware Overview System Unit

Computer and Peripherals

n Computer Hardware uRefer only to the Central processing unit (CPU), the circuitry that processes the data, and the computer’s memory. Part 1: Inside the System Unit n Peripherals uAll additional hardware components grouped around the CPU and memory

Computer Hardware Overview System Unit nIt is a Box-like case that contains computer’s electronic components nSometimes called the Chassis

1 Exposed System Unit How do computers represent data?

n Most computers are digital n Recognize only two discrete states: on or off

on 1 1 1 1 1

off 0 0 0 0 0

Binary System What is a byte? n Number system with two unique digits: 0 and 1 n Eight bits grouped together is a byte Binary Electronic Electronic 8-bit byte for the number 3 Digit (bit) Charge State

8-bit byte for the number 5

8-bit byte for the capital letter T

2 Three Popular Coding Systems to How is a Character Sent from Represent Data Keyboard to Computer?

° ASCII - American Step 1: Press letter T Standard Code for Information Interchange Step 2: Electronic signal for letter T sent to system unit ° EBCDIC - Extended Step 3: Signal changed to its Binary Coded Decimal ASCII code (01010100) and Interchange Code stored in memory ° Unicode - coding scheme capable of Step 4: After processing, binary code for letter T is converted to representing all world’s image on output device languages

Central Processing Unit (CPU) ? Components of the CPU

n Interprets and carries out basic instructions that operate a computer n Also called the Processor CPU

Control Arithmetic/ Unit Logic Unit (ALU)

3 Control Unit Machine Cycle? °Four operations of the CPU comprise a machine cycle ° Directs and coordinates operations in computer °Also called instruction cycle Control unit repeats • Instruction time (i-time) - time taken to fetch and decode four basic operations: • Execution time (e-time) - time taken to execute and store ° Fetch - obtain program Control Unit instruction or data item from e-time i-time memory ° Decode - translate instruction into commands ° Execute - carry out command ° Store - write result to memory

An example of a machine cycle Available CPU Packages 100 x 52 Student enters math problem (100 x 52) into single edge contact (SEC) cartridge computer’s dual inline package (DIP) memory Result in memory displays on monitor’s screen flip chip-PGA pin grid array (PGA) (FC-PGA) package © Peter Lo 2002 15 © Peter Lo 2002 16

4 CPU’s speed Measuring Two Designs used for the CPU

° According to how many CISC millions of (complex instruction set instructions per computing) RISC (reduced instruction second (MIPS) it ° Supports large number set computing) can process of instructions ° CPU executes complex ° Supports smaller instructions more number of quickly instructions ° CPU executes simple instructions more quickly © Peter Lo 2002 17 © Peter Lo 2002 18

Arithmetic/Logic unit (ALU) Pipelining

n CPU begins executing second instruction before n CPU component that performs execution part of completing first instruction. Results in faster processing the machine cycle Comparison Machine Cycle (without pipelining) (greater than, equal to, or less than) .and. Machine Cycle (with pipelining) .or. .not. Instruction 1 Arithmetic Logical Instruction 2 (addition, subtraction, (AND, OR, multiplication, and NOT) Instruction 3 division) © Peter Lo 2002 19 © Peter Lo 2002 Instruction 4 20

5 Register System Clock

° Temporary storage area n Synchronizes all computer operations that holds Stores n Each tick is clock cycle data and Stores results instruction instructions of calculation while it is being decoded

Stores location Stores data while from where MHz - one million instruction was ALU processes it ticks of system clock fetched GHz – one billion ticks © Peter Lo 2002 21 © Peter Lo 2002 of system clock 22

How do personal computer Microprocessor processors compare? n Single processor chip found in personal computers

6 Coprocessor Parallel Processing °Using multiple processors simultaneously to execute program faster Chip that assists processor in performing specific tasks One type is a floating-point coprocessor, also known as a °Requires special software math or numeric to divide problem and bring results together © Peter Lo 2002 coprocessor 25 © Peter Lo 2002 26

Memory: The CPU’s Electronic How is memory measured? Scratchpad n Memory is the temporary storage area for n Memory is measured by number of bytes available operating system, application programs, and data n It consists of one or more chips on motherboard n Each byte stored in unique address

7 Two types of System Unit Memory Random Access Memory (RAM)

n Memory chips that can be read from and written to by processor n Most RAM is volatile n The more RAM a computer has, the faster it volatile memory operates Loses its contents when nonvolatile thecomputer's computer's power power is memory isturned turned off off Does NOT lose its contents when computer’s power is memory module turned off

Two Basic Types of RAM chips Cache

n Dynamic RAM (DRAM) n Helps speed computer processes by storing frequently used instructions uMost common type and data uAlso called main memory n Also called Memory Cache, Cache n Static RAM (SRAM) Store , or RAM Cache u Used for special applications such as cache n L1 cache built in processor n L2 and L3 cache not built in u Faster and more reliable than DRAM chips processor n L2 advanced transfer cache most common

8 Read-Only Memory (ROM) Types of ROM n Memory chips that contain data, instructions, or information that is recorded permanently n Firmware uROM chips manufactured with permanently written data, instructions, or information BIOS n PROM (Programmable Read-Only Memory) Data can only ROM is (basic input/output system) uBlank ROM on which you can place items permanently be read; nonvolatile — Stored on ROM n EEPROM (Electrically Erasable Programmable Read-Only Memory) cannot be Contents not lost Sequence of instructions modified in when computer is computer follows to load uType of PROM containing microcode programmer can ROM turned off operating system and other erase files when you turn on the computer

Flash Memory CMOS

n Nonvolatile memory that can be erased n CMOS stand for Complementary Metal-Oxide electronically and reprogrammed Semiconductor memory n Used with handheld computers and digital n Stores information about the computer cameras, cellular phones, and automobiles utype of disk drives ukeyboard umonitor ucurrent time and date n Uses battery to retain information when computer is turned off

9 Memory Access Time BUS processor ° Channel that allows devices inside n Speed at which processor can access data from memory computer to communicate with directly each other n Measured in nanoseconds (ns), which is one billionth of a ° System bus connects processor system second and RAM bus n It takes 1/10 of a second to blink your eye; a computer can ° Bus width determines number perform up to 10 million operations in same amount of of bits transmitted at one time time ° Word size determines number of bits processor can interpret and execute at a given time

RAM © Peter Lo 2002 37 © Peter Lo 2002 38

Expansion Bus Expansion Slot n Allows processor to communicate with peripherals °An opening, or socket, where fastest memory next fastest circuit board is next fastest inserted into slowest motherboard

processor °Expansion card inserted in expansion slot

expansion card

PCI© busPeter Lo expansion 2002 slots ISA bus expansion slots 39 © Peter Lo 2002 expansion 40 slot

10 How are expansion cards used? Plug and Play

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

PCMCIA card Flash Memory Card

n Credit card-sized device used to add capabilities to n Adds memory to handheld computers, digital notebook computers music players, cellular telephones, and similar n PCMCIA stand for Personal Computer Memory Card devices International Association n Uses include modem, additional memory, and storage

11 mouse Port keyboard Different Types of Connectors USB °Connects USB external serial port printer (parallel devices to port)

system unit speaker monitor microphone

game port

network

telephone telephone line line out in svideo out FM reception © Peter Lo 2002 45 © Peter Lo 2002 46 cable TV

byte serial representation byte representation transmission for number 5 for number 1 Serial Port of data (00110101) Parallel Port byte representation byte for number 3 representation byte representation °Transmits one bit of for number 5 fornumber 5 (00110101) byte °Connects devices data at a time representation that can transfer for number 5 °Used to connect (00110101) more than one bit slow-speed devices, at a time, such as a such as mouse, printer keyboard, modem

DB-9 female DB-25 male connector connector

DB-9 male DB-25 female © Peter Lo 2002 47 © Peter Lo 2002 48 connector connector

12 DVD-ROM Universal Serial Bus port (USB) Bay drive CD-RW n Connector that supports newer peripherals and plug and n Open area inside drive play Zip drive system unit used n Other popular ports include 1394, MIDI, SCSI, and IrDA empty drive to install additional bay

equipment floppy disk drive

1394 port

USB port © Peter Lo 2002 49 © Peter Lo 2002 50

What ports are on a notebook Power Supply computer? n Converts alternating current (AC) to direct current (DC) keyboard/mouse n Some peripheral devices have AC adapter port

IrDA parallel port USB port serial port port video port

13 How is data transferred from a handheld computer? n An IrDA port allows the handheld computer to communicate wirelessly with other computers or devices n Handheld computers also can rest in a cradle, so you can Hardware transfer data to your desktop computer

IrDA port Part 2: Data Storage

cradle

How does storage differ from What is storage? memory? n Media and devices used to store and retrieve data, n Stores items for instructions, and information future use, rather When you than temporarily want to work When you are n Storage is with a file, finished with you read it the file, you nonvolatile, rather from storage write it from than volatile and place it in memory into memory storage

14 What is a storage device and a How does volatility compare? storage Medium?

storage device

Contents of Hardware that records Contents of and retrieves items to storagestorage retained when and from a storage retained when medium powerpower is is off off storage medium Physical material on which a computer keeps data, ScreenScreen display display and and contents contents of most RAM (memory) instructions, and © Peter Lo 2002 of most RAM (memory) 57 © Peter Lo 2002 58 erasederased when when power power is is off off information

Reading and Writing What is access time? n Amount of time it takes device to faster locate item on disk reading Memory Process of transferring data, n Defines speed of (RAM) instructions, and information disk storage device from a storage medium into writing more expensive Hard Disk memory cost speed Serves as a source Process of of input Compact Disc transferring items slower from memory to a storage medium Floppy Disk Serves as a

source of output less expensive Tape © Peter Lo 2002 59 © Peter Lo 2002 60

15 What is capacity? Memory vs. Storage (Summary) n Capacity is the number of bytes Storage Abbreviation Number Device Access Speed Cost per MB Term (characters) storage of bytes medium can hold Memory Cache Memory Fastest Highest Kilobyte KB 1 thousand RAM Fast High Megabyte MB 1 million Storage Hard disk Medium Medium Gigabyte GB 1 billion

Terabyte TB 1 trillion CD-ROM Disc Slow Low

Petabyte PB 1 quadrillion Backup Tape Very Slow Lowest

Floppy Disk What are the parts of a floppy disk? n Thin, circular, n Portable, inexpensive storage medium flexible film liner n Today’s standard disk is 3.5” wide enclosed between two liners shutter

metal hub

magnetic shell flexible © Peter Lo 2002 63 © Peter Lo 2002 coating thin 64film

16 How are floppy disk drives How does a floppy disk drive work? designated? 1: Shutter moves to 2: Signal sent to control movement 3: If write instruction, circuit board expose recording of read/write heads and disk verifies whether disk can be written to surface on disk One floppy drive 4: Motor causes drive A floppy disk to spin Step 2 Step 1 5: Motor positions Step 6 read/write heads Two floppy over correct drives location on disk drive A 6: Read/write heads read data Step 5 drive B from or write data on the floppy disk Step 4

Step 3

Tracks and Sectors Format (for Disk) sector n Process of preparing disk for n Track is narrow 18 per track recording band that reading and writing track forms full circle on 80 per n Formatting marks bad sectors as disk surface side unusable n Sector can store up to 512 bytes of data

80 tracks per side x 18 sectors per track x 2 sides per

17 How to take care a floppy? What is a write-protect notch? n Small opening notchnotch open open n Proper care helps maximize disk’s life with a cover that meansmeans youyou you slide cannotcannot write write write-protected n Floppy disk can last at least seven years onon the the disk disk n Protects floppy disks from being notch closed erased notch closed not write-protected meansmeans youyou accidentally cancan write write on on thethe disk disk

High-capacity Disk Drive Hard Disk n Uses disks with capacities of 100 MB and greater n High-capacity storage n Primarily used to backup files and transfer files n 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

18 How does a hard disk work? What is a Cylinder? 3: When software cylinder track 1: Circuit board controls 2: Small motor requests disk movement of head spins platters access, read/write activator and small motor heads determine n Location of a single track location of data through all platters Step 2 4: Head actuator Step 1 n Single movement of positions read/write head arms can read/write head arms over correct read same track on all location on platters to read or platters write data

Step 3 © Peter Lo 2002 Step 4 73 © Peter Lo 2002 74

A head crash! Disk Cache

n Occurs when read/write head touches platter surface n Portion of memory processor uses to store n Spinning creates cushion of air that floats read/write head frequently accessed items above platter gapgap is is half half the the processo diameterdiameter of of a a r dustdust particleparticle clearanceclearance disk cache betweenbetween head head andand platter platter is is hair hard disk approximatelyapproximately twotwo millionths millionths read/write head ofof anan inchinch dust first request for data smoke — to disk cache gap © Peter Lo 2002 75 © Peter Lo 2002 76 platter second request for data — to hard disk

19 What is a Partition? Removable Hard Disk? n Formatted hard disk divided into separate n Disk drive in which a plastic or metal case surrounds the hard disk so you can remove it from areas called drive C partitions the drive Designation for first n Each partition partition or for a single n Used for backup or to transfer files functions as if it partition on hard disk were a separate hard disk drive one hard disk divided into two partitions drive D Designation for second partition on hard disk © Peter Lo 2002 77 © Peter Lo 2002 78

What Windows Utilities Maintain How does RAID work? a Hard Disk Drive? n Disk system that duplicates data, instructions, and information to improve data reliability uMirroring has one backup disk for each disk uStriping stores data across multiple disks

mirroring (RAID Level 1)

striping System © Peter Lo 2002 79 © Peter Lo 2002 80 Tools

20 Internet Hard Drive? Advantages of Internet hard drive

n Service on Web that provides storage to computer users Large audio, video, n Most offer free storage and graphics files can be downloaded to an Files can be n Revenues come from advertisers Internet hard drive accessed from any instantaneously computer or device with Web access

Others can be authorized to access Allows offsite data from your Internet backups of data hard drive

Compact Disc (CD) -ROM How do you use a compact disc? CD InsertInsert disc, disc, CD n CD drives can read Push button label side up -R Push button label side up n Storage medium compact discs, toto slide slide out out the tray n Most PCs include some type of compact disc drive including audio the tray discs n Available in variety of formats CD -RW

DVD+RW

PushPush the the same same buttonbutton to to close close -ROM the tray © Peter Lo 2002 DVD 83 © Peter Lo 2002 the tray 84

21 How does a laser read data on a How data stored on a compact disc? compact disc? 1: Laser diode shines light Compact disc beam toward compact disc n Typically stores items in single track Step 123 label n Track divided into evenly sized sectors that store items 2: If light strikes pit, it scatters. If light strikes land, it is reflected back toward laser diode. pit land Compact disc 3: Reflected light lens lens sectors deflected to light-sensing 0 1 diode, which sends digital signal of 1. prism prism Absence of reflected light read as digital Light- Light- sensing sensing signal of 0. diode diode laser laser diode diode Single track spirals © Peter Lo 2002 85 © Peter Lo 2002 to edge of disc 86

How should you care for a What is a jewel box? compact disc? 1: Do not expose n Protective case for compact disc 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 jewel box 6: Hold disc by its edges

22 What is a CD-ROM? CD-R (Compact Disc-Recordable) n Compact disc that uses same laser technology as audio n Compact disc onto which you can record text, graphics, CDs for recording music and audio n Cannot erase or modify contents n Write on CD-R using CD burner (recorder) or CD-R drive n Typical CD-ROM holds about 650 MB and special software n Commonly used to distribute software and games n CD-R drive can read and write both audio CDs and standard CD-ROMs n Cannot erase disc’s contents

CD-RW (compact disc-rewritable) How to Create Audio CD? 1 Step 1: Artist composes song and creates CD n Erasable disc you can write on Multiple Times 2a 2b Step 2a: Song stored on audio CD n Must have a CD-RW disc, CD-RW software, and purchased by user and CD-RW drive 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 5 OR 3a 3b Step 3b: User downloads song as audio file to hard disk Step 4: User copies file to CD-RW disc Step 5: User listens to song on personal computer or removes 4 © Peter Lo 2002 91 CD© Peterand Lolistens 2002 to song 92 on portable CD player

23 DVD-ROM (Digital Video Disc- How does a DVD-ROM store data? ROM) n High capacity compact disc capable of storing n Two layers of pits are used, where lower layer is from 4.7 GB to 17 GB semitransparent n Must have DVD -ROM drive or DVD player to n Laser can read through it to upper layer read DVD-ROM n DVD+RW is a rewritable DVD n Primarily used for movies n Next -generation software will be delivered on DVD

Tape Sequential Access vs. Direct Access n Magnetically coated ribbon of plastic capable of storing n Sequential Access large amounts of data and information at a low cost uReading and writing data consecutively n Primarily used for backup uMethod used for tape n Direct Access uCan locate a particular data item or file immediately uMethod used for floppy disks, hard disks, and compact discs uAlso called Random Access

24 Enterprise Storage System Miniature Mobile Storage Media n Strategy that tape library focuses on n Handheld devices use to augment internal storage availability, protection , CD-ROM CompactFlash 40 MB Cartridge RAID jukeboxes Digital cameras, notebook organization, and computers backup of storage in a company Memory Stick 2 to 256 MB Memory Card Digital cameras, handheld computers, notebook computers, servers printers, cellular telephones Microdrive 1 GB Memory Card Digital cameras, handheld computers, music players, video cameras SmartMedia 2 to 128 MB Memory Card Digital cameras, handheld © Peter Lo 2002 97 © Peter Lo 2002 computers, photo printers, 98 Storage area network Network Storagestorage Internet backup cellular telephones

Smart Card Types of smart cards n Intelligent smart card contains Store data such as n Stores data on thin microprocessor embedded in processor and has input, photographs, music, books, credit card process, output, and storage and video clips capabilities

n Memory card has only storage Store a prepaid dollar amount capabilities that is updated when the card is used

Store patient records, smart card vaccination data, and other healthcare information

Store tracking information such as customer purchases or © Peter Lo 2002 99 © Peter Lo 2002 employee attendance 100

25 Electronic Money Microfilm and Microfiche n Means of paying for n Store microscopic images of goods and services documents on a roll or a sheet of film over the Internet Bank issues unique digital n Images recorded using a computer n Also called cash numbers When you output microfilm (COM) recorder purchase digital e-money or digital that represent an amount of money cash, the amount cash of money is withdrawn from your bank account To use the card, Microfilm swipe it through Microfiche Uses a 100- to 215- a card reader foot roll of film Uses a small sheet of film, usually 4” x 6” © Peter Lo 2002 101 © Peter Lo 2002 102

Life expectancies of various media What is a backup? n Duplicate of file, program, or disk that you can use if original is lost, damaged, or destroyed

instructions

information data

26 What is input? DATA Susan works 42 hours at $300/hr n Data uUnprocessed Hardware facts, figures, and symbols n Instructions Part 3: Input and Output uPrograms uCommands USER RESPONSES uUser responses Yes, the timecard entries are correct No, the timecard entries are not correct COMMANDS print the timecard PROGRAMS timecard hard disk © Peter Lo 2002 105 © Peter Lo 2002 INSTRUCTIONS 106

What is an input device? How is the keyboard divided?

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

video input n Function keys voice input keyboard function keys

scanners pointing and reading device devices typing area digital numeric keypad © Peter Lo 2002 camera107 © Peter Lo 2002 108

27 Portable Keyboard Ergonomic Keyboard

n Full-sized keyboard you conveniently can attach and n Designed to minimize strain on hands and wrists remove from a handheld computer n Ergonomics incorporates comfort, efficiency, and safety into design of items in workplace

Alternative forms for commands Mouse

n Many programs allow you to use button, menu, or n Pointing device that fits under palm of hand function key to obtain same result n Controls movement of pointer, also called mouse pointer, on screen Command Button Menu Function Key(s) n Pointer on screen takes several shapes Copy Edit|Copy SHIFT+F2

Open File|Open CTRL+F12

Print File|Print CTRL+SHIFT+F12

28 How does mechanical mouse work? How does an optical mouse work? wheel n Senses light to detect backback wheel n Rubber or metal ball is mousemouse wheelwheel button mouse’s movement buttonbutton button on its underside buttonsbuttons buttonbutton n More precise than n Movement of mouse forward mechanical mouse forward translates into signals buttonbutton n Connect using a cable or computer understands wireless

opticaloptical sensorsensor mousemousepadpad

ball © Peter Lo 2002 ball113 © Peter Lo 2002 114

Common mouse operations Trackball

n Point n Stationary pointing device with a ball on its top n Click n To move pointer, rotate ball with thumb, fingers, n Right-click or palm of hand n Double-click n Drag n Right-drag n Rotate wheel trackball n Press wheel

29 Touchpad Pointing Stick

n Small, flat, rectangular pointing device sensitive to n Pointing device shaped like pencil eraser pressure and motion positioned between keys on keyboard

touchpad

Joystick and Wheel Light Pen

n Joystick is vertical lever mounted on a base n Handheld input device that contains light source or can n Wheel is steering-wheel type input device detect light n Pedal simulates car brakes and accelerator n Press light pen against screen surface and then press button on pen

joystick wheel

pedal

30 Touch Screen Stylus

n Touch areas of screen with finger n Looks like a ballpoint pen, but uses pressure to write text and draw lines n Often used with kiosks n Used with graphics tablets and handheld computers

stylus or pen

touch screen

Electronic Signature Handwriting Recognition

n Pen and graphics tablet used with special software for n Translates handwritten letters and symbols into handwriting recognition characters that the computer can understand n Legal as ink signature n Also called e-signature

31 MIDI (Musical Instrument Digital How does voice recognition work? Interface) Step 1: Dictate n External device, such as electronic piano keyboard, You’re right! Step 2: Convert analog to digital to input music and sound effects

Natural Language Step 4: Most likely match Engine selected … Your write … You’re right … Your right Step 3: Check database for match your, you’re Matches © Peter Lo 2002 125 © Peter Lo 2002 126 right, write

How is a data entered into a Digital Camera handheld device? stylus n Allows you to take digital pictures n Images viewable immediately on camera n Download to computer handwriting recognition characters voice input stylus n Post pictures to Web

stylus

transfer data from on-screen desktop keyboard computer © Peter Lodigital 2002 camera 127 © Peter Lo 2002 128 portable keyboard

32 How does a digital camera work? Resolution 1: Take picture Step 1 2: Image focuses on CCD n Sharpness and clarity of image 3: CCD generates analog Step 2 signal that represents n Higher the resolution, the better the image quality, image but the more expensive the camera 4: Analog signal Step 3 converts to digital signal n Pixel (pi cture element) is single point in electronic Step 4 5: Digital signal processor image (DSP) adjusts quality Step 5 n Greater the number of pixels, the better the image 6: Transfer image to computer quality 7: View and manipulate image Step 6 Step 7 © Peter Lo 2002 129 © Peter Lo 2002 130

Video Input PC Video Camera

n Process of entering full-motion recording into computer n Digital video camera that allows home user to record, edit, n Also called Video Capture and capture video and still images, and to make video n Video capture card is expansion card that converts analog telephone calls on Internet video signal into digital signal n Also called PC Camera digitaldigital video video that computer understands cameracamera PC video n Video compression camera

analoganalog video video camera © Peter Lo 2002 camera 131 © Peter Lo 2002 132

33 Web Cam Videoconferencing

n Video camera whose output displays on a Web page n Two or more geographically separated people who use n Also called a cam network on the Internet to transmit audio and video data n Streaming cam shows moving images by sending continual n Whiteboard is another window on screen that can display stream of pictures notes and drawings simultaneously on all participants’ screens

Web cam video output © Peter Lo 2002 133 © Peter Lo 2002 134

Scanner How does a flatbed scanner work?

1: Place document n Device that captures data directly from source document face down 2: Bright light scans uSource document is original form of data document 3: Image reflected Step 1 into mirrors 4: Light converted to Step 2 analog electrical and Step 3 then to digital signal 5: Digital information sent to computer OCR 6: Print or save document

flatbed Step 4 © Peter Lo 2002 scanner 135 © Peter Lo 2002 Step136 6 Step 5

34 Various types of scanners Image Processing

Pen or handheld n Capturing, storing, analyzing, displaying, printing, and manipulating images n Converting paper documents Flatbed into electronic form n Also called Imaging

Drum

Optical Reader OCR Font

n Device that uses light source to read characters, n OCR font, such as OCR-A, used with OCR marks, and codes and then converts them into devices digital data n OCR device determines characters’shapes by uOptical character recognition (OCR) detecting patterns of light and dark uOptical mark recognition (OMR) n OCR software converts shapes into characters the uBar code scanner computer can understand

35 Turnaround Document Optical Mark Recognition (OMR) n You return it to company that n Reads hand-drawn pencil marks, such as small sent it circles or rectangles

numbers are read by OCR device when document is returned

Bar Code Scanner Bar Code

n Uses laser beams to read bar codes n Identification code that consists of a set of vertical lines and spaces of different widths n Universal Product Code (UPC)

NumberNumber system system charactercharacter identifies identifies typetype of of product product

Check character verifies ManufacturerManufacturer Check character verifies accuracy of scanned identificationidentification number number accuracy of scanned UPC symbol (Kellogg(Kellogg’s,’s, in in this this case) case) UPC symbol bar code scanners ItemItem number number (10 (10 oz. oz. box box © Peter Lo 2002 143 © Peter Lo 2002 144 ofof Froot FrootLoopsLoops

36 Magnetic Ink Character Wireless Input Recognition Reader (MICR) n Can read text printed with magnetized ink n Handheld computer or device used to collect data n Banking industry almost exclusively uses MICR for check wirelessly at the location where transaction or event takes processing place n Data transferred later to desktop computer through docking station

Input Devices for Physically New developments for physically pointing Challenged Users device for challenged users those with motor n Gesture recognition disabilities uComputer will detect human motions uComputers with this capability have potential to keyguard for limited recognize sign language, read lips, track facial hand mobility movements, or follow eye gazes n Implantation uFor paralyzed or speech- impaired individuals uDoctor will implant computerized device containing transmitter into brain onscreen keyboard uAs user thinks, transmitter will send signals to computer speech recognition © Peter Lo 2002 147 © Peter Lo 2002 148

37 What Is output? Output Device n Data that has been processed into a n Any hardware component that can convey useful form, called information to a user information graphics text

monitor speakers

printer

video

Display Device CRT Monitor

n Television-like n Large sealed, glass cathode ray tube screen n Information on a display device sometimes is n Screen coated with tiny called Soft Copy 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

38 Typical sizes for CRT monitors Liquid Crystal Display (LCD) n 15, 17, 19, 21, and n Type of flat-panel display 22 inch screen size n Uses liquid crystals between two sheets of n Viewable size is material to present information on screen diagonal n Electric current passes through crystals, which measurement of screen size creates images on the screen actual viewing area provided by the viewable size monitor

Some features of LCD screens Web-enabled device

n Lightweight and compact n Allows access to the Web or n Consumes less than one- e-mail third of the power than uCellular telephones does a CRT monitor uPagers n Ideal for notebook and n Many use monochrome LCD handheld computers displays to save battery power

39 Two technologies used for LCD Electronic Book (e-book) monitors n Small, book-sized computer that uses an LCD screen n Active-matrix display n Allows users to read, save, highlight, bookmark, and add uCan display high-quality color viewable from notes to online text all angles n Download new book content from Web n Passive-matrix display uColor often not as bright uImages best viewed when working directly in front of display

Gas Plasma Monitor Display resolution n Flat-panel display uses layer of gas plasma n Describes the sharpness and clarity of image between two sheets of material n The higher the resolution, the sharper the image and the more that can display on the monitor n Larger screen sizes and higher display quality than LCD, but much more expensive 800 x 600 800 horizontal most common pixels

1280 x 1024 maximum resolution 600 vertical of most monitors pixels Total of 480,000 2048 x 1536 pixels on screen maximum for © Peter Lo 2002 159 high-end© Peter monitors Lo 2002 160

40 Dot Pitch Refresh Rate n Measure of the distance between pixels n Speed at which monitor redraws images on the n Sometimes called Pixel Pitch screen n Smaller the distance between the pixels, the n Should be fast enough to maintain a constant, sharper the image flicker-free image n Use a monitor with a dot pitch of 0.29 millimeters n High-quality monitor will provide refresh rate of or lower to minimize eye fatigue at least 75 hertz n Image on the screen redraws itself 75 times per second

How does video travel from the Video Card processor to a CRT monitor? n Converts digital output from computer into analog 1: Processor sends digital data Step 1 video signal to video card Step 2 2: Video card converts digital n Controls how display device produces picture data to analog signal n Also called Graphics Cardor Video Adapter 3: Analog signal sent via cable to CRT monitor Step 3 4: CRT separates signal into red, green, and blue signals 5: Electron guns fire color signals to front of CRT Step 4 6: Image displays Step 5 Step 6

41 8-bit video 28 = Bit Depth 2 x 2 x What are video standards card n Number of bits a video 2 x 2 x Uses 8 bits to store 2 x 2 x card uses to store information about n Video Electronics Standards Association (VESA) information about each each pixel 2 x 2 = pixel 256 develops video standards Can display 256 n Also called Color Depth colors n Determines number different colors of colors a video card can display n Greater the number 24-bit video of bits, better the resulting card 24 image 2 = Uses 24 bits to 16.7 million store information colors about each pixel

What are various video card Electromagnetic Radiation (EMR) configurations? n Magnetic field that travels at speed of light n Small amount produced by all CRT monitors

Sit at arm’s LCD monitors length from do not pose EMR is greatest CRT this risk on sides and back of CRT monitor

42 ENERGY STAR® Program Interactive TV

n Program to encourage manufacturers to create n Two-way communications technology in which energy-efficient devices that require little power users interact with television programming when not in use n HDTV works directly with interactive TV n Monitors and devices meeting guidelines display Play ENERGY STAR® label Select a games movie from Bank a central library of Vote or movies Shop respond to network questionnaires © Peter Lo 2002 169 © Peter Lo 2002 170

Printer Impact Printer

n Output device that produces text and graphics on paper n Forms characters by striking a mechanism against ink n Result is hard copy, or printout ribbon that physically contacts paper n Two orientations n Ideal for printing multipart forms portraitportrait n Can withstand dusty environments, vibrations, and extreme orientation orientation temperatures

43 Dot-matrix Printer How does dot-matrix printer work?

n Impact printer that produces printed images when tiny wire n When ribbon presses against pins on print head mechanism strike inked ribbon paper, it creates dots that form n Most use continuous-form paper 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

continuous-form paper dots form characters

Line Printer Non-impact printer n High-speed impact printer that n Forms characters and graphics on piece of paper prints entire line at a time without actually striking paper 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 ink-jet printer laser printer thermal printer © Peter Lo 2002 175 © Peter Lo 2002 176

44 Ink-jet Printer Resolution of a printer

n Non-impact printer forms characters and graphics n Sharpness and clarity of characters by spraying tiny drops of liquid ink onto piece of n Measured by number of dots per inch (dpi) paper printer can output n Most popular type of color printer for home use 300 600 1,200 dpi dpi dpi

How does an ink-jet printer work? Laser Printer Print cartridge 1: Small resistor heats ink, causing n High-speed, high-quality non-impact printer ink to boil and form vapor n Prints text and graphics in very high-quality resolution, bubble ranging from 600 to 1,200 dpi firing n Typically costs more than ink-jet printer, but is much faster nozzle chamber print head resistor 2: Vapor bubble forces ink through nozzle 3: Ink drops onto paper ink dot

4: As vapor bubble bubble collapses, fresh ink is nozzle © Peterdrawn Lo 2002 into firing chamber ink 179 © Peter Lo 2002 180 paper

45 How does a laser printer work? Thermal Printer 1: Drum rotates as paper is fed through 2: Mirror deflects n Generates images by pushing electrically heated laser beam across rotating mirror surface of drum pins against heat-sensitive paper 3: Laser beam drum n Ideal for small devices, such as adding machines creates charge that causes toner to stick to drum 4: As drum rotates, toner transfers from drum to rollers paper 5: Rollers use heat and pressure to fuse toner to paper

Photo Printer Label Printer n Color printer that n Small printer that prints on adhesive type material produces photo that can be placed on a variety of items lab quality n Most also print bar codes and e-stamps pictures and Select image to print, prints everyday number of copies, and documents size of print

46 Portable Printer Plotter n Small, lightweight ink-jet or thermal printer that n Sophisticated printer used to produce high-quality allows mobile user to print from notebook or drawings handheld computer while traveling n Large-format printer similar to plotter and is used to print quality color prints

Audio Output Device Voice Output n Computer component that produces music, speech, n Computer talks to you through speakers on

and other sounds computer RealPlayer n Speakers and headsets are common devices speakers

47 Internet Telephony Data Projector n Allows you to have a conversation over the Web, n Device that takes image from a computer screen just as if you were talking on the telephone and projects it onto a larger screen

data projector

Facsimile (fax) Machine Fax Modem n Device that transmits and n Modem that allows you to send and receive receives documents over electronic documents as faxes telephone lines

fax machine

internalinternal faxfax modemmodem cardcard in in externalexternal fax fax systemsystem © Peter Lo 2002 191 © Petermodemmodem Lo 2002 unitunit192

48 Multifunction Device (MFD) Terminal

n Provides the functionality of a printer, scanner, n Device that performs both input and output copy machine, and fax machine

special- dumb intelligent purpose terminals terminals terminals

all in one

Dumb Terminal keyboard and monitor Intelligent Terminal host computer n Has a keyboard and n Has monitor, keyboard, memory and monitor, but no processor processor or memory n Similar to a PC in that it can perform tasks independent of host n Connects to host computer computer that performs n Programmable processing and then sends output back

49 Point-of-Sale (POS) terminal Automated Teller Machine (ATM)

n Records purchases at point n Self-service banking where purchase is made machine that connects n Output from POS terminals to host computer serves as input to host through telephone computer network

POS terminal in a grocery store

Other output options for visually What is the Magnifier command? impaired users? n Windows Magnifier command enlarges text and n Change Window’s settings such as increasing size or changing color of text to make words easier to read other items in window on screen MagnifierMagnifier commandcommand n Blind users can work with voice output n Braille printer outputs information in Braille onto paper

LocationLocation of of mousemouse pointerpointer magnifiedmagnified atat toptop of of screen screen Braille printer © Peter Lo 2002 199 © Peter Lo 2002 200

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