Computer Confluence 7/e Chapter 3 Hardware Basics: Peripherals © 2006 Prentice-Hall, Inc.
Computer Confluence 7/eChapter 3Objectives Input devices and their roles in getting different types of information into the computer Output devices and the ways they make computers more useful The functionality of different types of storage devices The ways the components of a computer system fit together © 2006 Prentice-Hall, Inc.
Computer Confluence 7/eChapter 3Input: From Person to Processor Keyboard The most familiar input device Used to enter letters, numbers and special characters © 2006 Prentice-Hall, Inc.
Computer Confluence 7/eChapter 3Input: From Person to Processor Standard keyboard Ergonomic keyboards To address possible medical problems Place the keys at an angels that are easier on your arms and hands. Wireless keyboard Folding keyboards Used with palm-sizedcomputers One-handed keyboards Keyboards printed on membranes that can be rolled or folded like paper. © 2006 Prentice-Hall, Inc.
this standard-size fabric keyboard rolls up into a lightweight, compact package that can be tucked into a pocket, or briefcase.
Computer Confluence 7/eChapter 3Input: From Person to Processor Pointing Devices Mouse Portable computers : Touchpad (track pad) Pointing stick Trackball Other pointing devices : Joystick Graphics tablet stylus Touch screen © 2006 Prentice-Hall, Inc.
Variants of the Mouse • Trackballs • Upside down mouse • Hand rests on the ball • User moves the ball • Uses little desk space
Track pads Stationary pointing device Small plastic rectangle Finger moves across the pad Pointer moves with the pointer Popular on laptops Variants of the Mouse
Variants of the Mouse Track point • Little joystick on the keyboard • Move pointer by moving the joystick
Pen based input Tablet PCs, PDA Pen used to write data Pen used as a pointer Handwriting recognition Devices for the Hand
Touch screens Sensors determine where finger points Usually presents a menu to users ATM’s, Malls, Devices for the hand
Computer Confluence 7/eChapter 3Input: From Person to Processor Reading Tools Reads marks representing codes specifically designed for computer input © 2006 Prentice-Hall, Inc.
Computer Confluence 7/eChapter 3Input: From Person to Processor Optical-mark readers: use reflected light to determine the location of pencil marks on standardized test answer sheets and similar forms. © 2006 Prentice-Hall, Inc.
Computer Confluence 7/eChapter 3Input: From Person to Processor • Magnetic-ink character readers : read those odd-shaped numbers printed with magnetic ink on the checks. • Bar-code readers use light to read universal product code (UPC). They are attached to point of sale terminals (POS). These terminals send the scanned information to a mainframe computer => item’s price, calculate total. • Radio Frequency Identification Readers : use radio waves to communicate with Radio Frequency Identification (RFID) tags. When energized by a nearby RFID reader, an RFID tag broadcasts its unique identification number to the reader. which digitizes the information for input into a computer.
An RFID tag used for electronic toll collection RFID tags used in libraries: square book tag, round CD/DVD tag and rectangular VHS tag.
Computer Confluence 7/eChapter 3Input: From Person to Processor Because test forms, magnetic ink character, bar codes, and RFID tags were designed to be read by computers, the devices that read them are extremely accurate. Reading text from books, magazines, and other printed document is more challenging because of the great variety of printed text. • Optical character recognition (OCR) is the technology of recognizing individual characters on a printed page, so they can be stored and edited as text.
Computer Confluence 7/eChapter 3Input: From Person to Processor Before a computer can recognize handwriting or printed text, it must first create a digital image of the page that it can store in memory.=>scanner. A scanner doesn’t actually read or recognize letters and numbers on a page- it just makes a digital “ picture” of the page available to the computer.
Pen scanners : • looks like highlighters. • Wireless scanners that can perform character recognition. • pen-based computers such as the Tablet PC • can work without a keyboard • accept input from a stylus • handwritten recognition software to translate the user’s handwritten forms into ASCII characters.
Personal digital assistants (PDAs): • are handheld pen computers that serve as organizers, notebooks, communication devices, …. • Smart whiteboard: • serve as an input device for a PC. • board is stored as a digital image on the computer’s disk.
Digitizing devices • Before a computer can recognize hand-written or printed text, a scanner or other input device must digitize the information- convert it into a digital form-. • A scanner is an input devicethat can create a digital representation of a printed image.
Computer Confluence 7/eChapter 3Input: From Person to Processor Digitizing the Real World Scanners capture and digitize printed images Flatbed Slide scanner : scan only slides and negatives. Drum : larger and more expensive. Sheet-fed : small, portable, and inexpensive. © 2006 Prentice-Hall, Inc.
Drum scanner Slide scanner Sheet fedscanner
Computer Confluence 7/eChapter 3Input: From Person to Processor Digital camera Snapshots captured as digital images Digital images stored as bit patterns on disks or other digital storage media © 2006 Prentice-Hall, Inc.
Computer Confluence 7/eChapter 3Input: From Person to Processor Video digitizer Capture input from a: Video camera Video cassette recorder or television Convert it to a digital signal Stored in memory and displayed on computer screens Digital video camera can send video signals directly into a computer without a video digitizer. Videoconferencing People in diverse locations can see and hear each other Used to conduct long-distance meetings Video images transmitted through networks © 2006 Prentice-Hall, Inc.
Computer Confluence 7/eChapter 3Input: From Person to Processor Audio digitizers Digitize sounds from Microphones Other audio input devices Digital signals can be Stored Further processed with specialized software A digital signal processing chip compresses the stream of bits before it is transmitted to the CPU © 2006 Prentice-Hall, Inc.
Audiovisual Input Devices • Microphones • Used to record speech • Speech recognition • “Understands” human speech • Allows dictation or control of computer • Matches spoken sound to known phonemes • Enters best match into document
Computer Confluence 7/eChapter 3Input: From Person to Processor Speech recognition software Converts voice data into words that can be edited and printed © 2006 Prentice-Hall, Inc.
Computer Confluence 7/eChapter 3Input: From Person to Processor Sensors Designed to monitor physical conditions Temperature, humidity, pressure Provide data used in: Robotics Environmental climate control Weather forecasting Medical monitoring Biofeedback Scientific research © 2006 Prentice-Hall, Inc.
Computer Confluence 7/eChapter 3Output: From Pulses to People Screen Output A monitor or video display terminal (VDT) displays characters, graphics, photographic images, animation and video Video adapter —connects the monitor to the computer a circuit board installed in a slot inside the system unit VRAM or video memory —a special portion of RAM to hold video images the amount of VRAM determines the max. resolution and color depth. the more video memory, the more picture detail is displayed. © 2006 Prentice-Hall, Inc.
Computer Confluence 7/eChapter 3Output: From Pulses to People Monitor size: Measured as a diagonal line across the screen Resolution: The number of pixels displayed on the screen Pixels (or picture elements): tiny dots that compose a picture The higher the resolution, the closer together the dots and the clearer the image. Image quality is affected by resolution and color depth (or bit depth) Color depth refers to the number of different colors a monitor displays at one time © 2006 Prentice-Hall, Inc.
Monitors • Categorized by color output • Monochrome • One color with black background • Grayscale • black, white, and Varying degrees of gray • Color • Display 4 to 16 million colors
Computer Confluence 7/eChapter 3Output: From Pulses to People Monitor classes CRTs (cathode-ray tubes) LCDs (liquid crystal displays) are now more popular Overhead projection panels Video projectors Portable computers © 2006 Prentice-Hall, Inc.
Monitors • Cathode Ray Tube (CRT) • Electrons fired from the back • Electrons excite phosphor to glow • Phosphor is arranged in dots called pixels • CRT drawbacks • Very large • Very heavy • Use a lot of electricity
Flat-panel Monitors • Liquid Crystal Display (LCD) • Commonly found on laptops • Desktop versions exist • Solve the problems of CRT • Fluorescent lights provide illumination • Electro-luminescent displays (ELD) • Similar to LCD • Uses phosphor to produce light • Plasma monitor • Gas is excited to produce light
Computer Confluence 7/eChapter 3Output: From Pulses to People Paper Output Printers produce paper output or hard copy Two basic groups of printers: Impact printers nonimpact printers © 2006 Prentice-Hall, Inc.
Commonly Used Printers • Impact printers • Line printers • Dot-matrix printers • Generate output by striking the paper, ribbon, and print hammer together. • Uses an inked ribbon • Non-impact printers • Use methods other than force • Tend to be quiet and fast
Commonly Used Printers • Line printers - Impact printer - speedy but noisy - limited to printing characters.
Commonly Used Printers • Dot matrix printers • Impact printer • Used to print to multi-sheet pages • Print head strikes inked ribbon • Speed measured in characters per second
Output: From Pulses to People • Non-impact printers • Laser printers • Laser beam reflected off a rotating drum to create patterns of electrical charges • Faster and more expensive than dot matrix printer • Produce High-resolution output • Color or black and white • Print process • Laser draws text on page • Toner sticks to text • Toner melted to page • Speed measured in pages per minute • Quality expressed as dots per inch
Output: From Pulses to People • Non-impact printer • Inkjet printers • Sprays ink onto paper to produce printed text and graphic images • Prints fewer pages/minute than laser printer • High-quality color costing less than laser printer • Speed measured in pages per minute • Quality expressed as dots per inch
High-Quality Printers • Photo printers • Produces film quality pictures • Prints very slow • Prints a variety of sizes
Computer Confluence 7/eChapter 3Output: From Pulses to People Multifunction printer or MFP combines a scanner, printer and a fax modem Plotter: an automated drawing tool that can produce large, finely scaled engineering blueprints and maps © 2006 Prentice-Hall, Inc.
Computer Confluence 7/eChapter 3Output: From Pulses to People Fax Machines and Fax Modems Facsimile (fax) machine Sending: fax machine scans each page as an image, converts the image into a series of electronic pulses, sends those signals over phone lines to another fax. Receiving: fax machine uses the signals to reconstruct the image and print black-and-white facsimiles or copies of the originals © 2006 Prentice-Hall, Inc.
Fax Machines and Fax Modems • Fax modem: • directly from PC to fax machine via modem & phone line • translate the document into signals that can be sent over phone wires. • Decoded by the receiving fax machine. (remote printer) • receive transmission from fax machine (remote scanner)
Computer Confluence 7/eChapter 3Output: From Pulses to People Output You Can Hear Sound card Enables the PC to: Accept microphone input Play music and other sound through speakers or headphones Process sound in a variety of ways Synthesizers Specialized circuitry used to produce music, noise electronically. © 2006 Prentice-Hall, Inc.
Computer Confluence 7/eChapter 3Output: From Pulses to People Controlling Other Machines Output devices take bit patterns and turn them into non-digital movements Robot arms Telephone switchboards Transportation devices Automated factory equipment Spacecraft Force feedback joystick © 2006 Prentice-Hall, Inc.
Computer Confluence 7/eChapter 3Output: From Pulses to People Rules of Thumb: Ergonomics and Health Choose equipment that’s ergonomically designed Create a healthy workspace Build flexibility into your work environment Rest your eyes Stretch to loosen tight muscles Listen to your body Seek help when you need it © 2006 Prentice-Hall, Inc.
Describing Storage Devices • Store data when computer is off • Two processes • Writing data • Reading data