Chapter Topics Chapter 2 Looking at Computers: Understanding the Parts Functions of a computer Data versus information Bits and bytes Input devices Output devices System unit Ergonomics 1 Computers Are Data Processing Devices Computer s four major functions: Inputs (user inputs data) Processes data into information Outputs data or information Stores data and information 2 Data vs. Information Data: Representation of a fact, figure, or idea Information: Organized, meaningful data Bits and Bytes: The Language of Computers Bit Binary digit 0 or 1 Byte Eight bits Each letter, number, and character = a string of eight 0s and 1s 3 4 How Much Is a Byte? Name Abbreviation Number of Bytes Relative Size Byte B 1 byte Can hold one character of data. Kilobyte KB 1,024 bytes (2 10 bytes) Can hold 1,024 characters or about half of a double-spaced typewritten page. [Measure Word, Excel, and some picture files in KB] Megabyte MB 1,048,576 bytes (2 20 bytes) Can hold ~768 pages of typed text. [Measure some picture files in MB] Gigabyte GB 1,073,741,824 bytes (2 30 bytes) Approximately ~786,432 pages of text which is a stack of paper ~262 feet high. [Measure older hard drives [750 GB] Terabyte TB 1,099,511,627,776 bytes (2 40 bytes) This represents a stack of typewritten pages ~ 51 miles high. [Measure new hard drives (1-3 TB) in TB] Petabyte PB 1,125,899,906,842,62 bytes (2 50 The stack of pages is now 52,000 bytes) miles high, or approximately onefourth the distance from the Earth to the moon. Exabyte EB 1,152,921,504,606,846,976 bytes The stack of pages is now 52 million (2 60 bytes) miles high, or just about twice the distance between the Earth and Venus. Zettabyte ZB 1,180,591,620,717,411,303,424 The stack of pages is now 52 billion bytes (2 70 bytes) miles high, some 20 times the distance between the Earth and Pluto. 5 Metric prefixes prefix abbrev # word -- B 1 byte kilo KB 1,000 bytes thousand mega MB 1,000,000 bytes million giga GB 1,000,000,000 bytes billion tera TB 1,000,000,000,000 bytes trillion peta PB 1,000,000,000,000,000 bytes quadrillion 6
Computer Hardware Hardware: Any part of the computer you can touch. Computer Software Software: Programs that enable hardware to perform different tasks Application software System software 7 8 Types of Computers Notebook: Portable computer Desktop: Used at a single location Mainframe: Supports hundreds of users simultaneously Supercomputer: Performs complex calculations rapidly Embedded: Self-contained computer performing dedicated functions Input Devices Devices used to enter information or instructions into the computer Keyboard Mouse/ pointing device Microphone Scanner Digital camera Stylus 9 10 The QWERTY layout is standard on most PCs Enhanced keyboard features include number, function, and navigation keys. Keyboards trackpoint touchpad number pad Notebook keys fn key in conjunction with function key does special function such as volume Notebook Keyboard Fn key Touchpad trackpoint 11 12
Dvorak Keyboards Virtual laser, Tablet and stylus Puts the most commonly used keys on home keys Reduces distance of finger stretches Not enough interest to change from QWERTY though Virtual laser keyboard Configurable keyboard 13 14 Stores what you write, later transfer to computer Digital pen Wireless RF keyboard With the RF (radio RF keyboard frequency) wireless technology, the keyboard contains a transmitter that transmits the radio waves to a receiver that sits next to the keyboard and is attached to the tower. (upto 100 ft) Bluetooth wireless keyboard is a shorter range wireless 15 2008 Prentice-Hall, Inc. 16 Mice Optical mouse Doesn t need as dirty no mouse pad necessary Trackball Easier on wrists Stays stationary on desk Wireless Use radio or light waves Integrated pointing device Touchpad Scanners Text Images Digital cameras Images Video Other Input Devices Flatbed scanner Digital camera Handheld scanner Camcorder Trackpoint 17 18
Other Input Devices Image Input Game controllers Touchscreens DS game Tablet PC (see pic) Digital pens Digital cameras, camcorders, and cell phones Pictures Video Webcams Live video 19 20 Microphones used for: Podcasts Videoconferencing Internet phone calls Speech recognition Inputting Sound Input Devices for the Physically Challenged Visual impairments Voice recognition Keyboards with large keys On-screen keyboards Motor control issues Special trackballs Head-mounted devices 21 22 Output Devices Send processed data out of the computer Monitors Printers Output devices make: Soft copies (video, sounds, control signals) Hard copies (print) Monitor Types and advantages CRT Cathode Ray Tube Legacy (as in old ) LCD Liquid Crystal Display Uses far less space More energy efficient More environmentally friendly Less eye strain A 17 monitor IS 17 brighter 23 2008 Prentice-Hall, Inc. 24
LCD Monitor Features Screens are grids made up of millions of pixels. (pixel = picture elements, dots on screen) Each pixel is composed of red, blue, and green subpixels LCDs: Liquid crystal, light waves, etc result in variations of red, green blue colors of images formed n scrn (CRTs: Pixels illuminated by electron beam that passes back/forth across screen.) 25 LCD Quality Factors (recommended measures in parentheses) : Resolution - depends on # of pixels on screen; (native resolution is the maximum resolution) Viewing angle - poorer angles than the CRT (degrades after 150 degrees) Contrast ratio - Diff between brightest white & darkest black (400:1 or 1000:1) Brightness - amt of light when showing pure white (300 cd/m 2 ) Response time time for pixel to change color (smaller # better; for movies, games) 26 Screen Size 21 monitor: 1680x1050 pixels (typical resolution) 19 monitor: Some resolutions: 1440x900, 1280x1024 Need 1920x1080 for hi-def movies Wide screen vs. standard 4:3 ratio; wide good for 2 documents viewed at once... Large resolution fits more on screen (images are smaller); Small res fits less (images are larger) Other Video Output Touch-screen monitors Double as both input and output devices Monitors w/ built-in cam, mic, card reader, USB hub Data projectors Project a computer image to wall for sharing with group 27 28 Impact printers Dot-matrix Nonimpact printers Inkjet Laser Specialty printers All-in-one Plotters Thermal printers Printers 29 Nonimpact Printers Inkjet and Laser Inkjet (spray tiny drops of ink. ) Entry level model is less expensive Full color printing excellent choice for photo printing Laser (uses toner) There are B & W laser printers and color laser printers (Color lasers very expensive) Excellent quality, quiet When purchasing a printer consider price of consumables (ex: cartridges and toner), speed (ppm, pages per minute), resolution (dpi, dots per inch), memory, color 2008 Prentice-Hall, Inc. 30
CPU RAM (S+T) Expansion cards and slots Built-in components The Motherboard Expansion Cards Add functions Provide new connections for peripheral devices Common types: Sound Modem (telephone) Video (VGA or graphics) Network (NIC=network interface card) 31 32 Random access memory (RAM): Stores instructions and data Temporary (volatile) storage Consists of several memory cards or modules RAM vs. ROM Read-only memory (ROM): Stores start-up instructions Permanent storage Memory Module Random access memory (RAM) Copy of program instructions/data in RAM when program running Temporary (volatile) storage Operates in nanosec. Common size: (see chap 6: 4GB at least; high end computer may have 24GB) 33 34 Central Processing Unit (CPU) Referred to as the brains of the computer Controls all functions of the computer Processes all commands and instructions Can perform billions of tasks per second Common speeds: 2-4 GHz (Gigahertz) (discussed also in chapter 6) 3 GHz = ~ 3 billion machine cycles per sec CPU Performance Measures Speed - common 2-3 ghz 3 GHz ~ 3 billion machine cycles per sec Megahertz (MHz) Gigahertz (GHz); Cores (simultaneous paths executing instruct s; see picture on right) Single Dual Quad 35 36
Drive Bays Internal drive bays: Cannot be accessed from outside the system Are reserved for internal hard drives External drive bays: Can be accessed from outside the system CD or DVD drives Floppy and Zip drives (legacy technology) Power control Drive bays Memory card reader Productivity ports The Front Panel 37 38 Hard Drive Permanent storage Internal or external versions Stores data, program instructions as they are running (Completes tasks in millisecs vs RAM s nanosecs.) (Spin rate: 5400, 7200 rpm) Common: 500 GB, 640 GB, 1TB, 2TB (T=Tera, trillion) Optical Storage Compact discs (CDs) Digital video discs (DVDs) Blu-ray discs (BDs) 39 40 Storage Media Capabilities Flash Drives/Flash Memory See p71 (8e), teacher notes Typo: DVD DL is 8.5 GB not 88.5 Flash drives (jump drives) Newer storage alternative Plug into USB ports Flash memory cards Slide into slots in the system 41 42
USB Serial and parallel Audio and video FireWire Types of Ports Connectivity Ethernet Modem 43 Ports for peripheral devices Types of ports w/ speeds (= transfer rates): Serial 115K bps, Parallel 500K bps USB 480M bps (2.0) USB 4800M bps (3.0) Ethernet 100M,1000M bps Tele. modem 56K bps FireWire (or 1394) 400M bps, 800M bps, and 3.2G bps (= 3200M bps) Audio ports VGA (monitor), DVI, s-video HDMI 2008 Prentice-Hall, Inc. 44 Expansion cards: New port standards Expansion hubs: Enable several devices to be connected to a port Adding Ports Power Controls Power-on button: Turns on system; Use Shut Down procedure or may use Power button to turn off. Called a cold boot when turned on for the first time that day (Warm boot is restart) Keep computer on but use conservation of energy: Sleep mode, Hibernate Only turn off computer if use it very little Change power settings: Control Panel (icon view) > Power Options 45 46 Ergonomics (1) Ergonomics procedures, equipment for minimizing injury or discomfort while using the computer (minimize RSI - repetitive stress injury) Steps to follow: Position monitor correctly (eyse at top of monitor) Use adjustable chair (back of knees not pressed against chair that is too high, feet on floor) Wrists flat over keyboard, not presses on edge of table Take breaks Ensure adequate lighting Ergonomics (2) Play PMPs (personal media players) at 60 decibels or less Small screens blink often, take a break to focus at 8ft Backpack place over both shoulders not one 2008 Prentice-Hall, Inc. 47 2008 Prentice-Hall, Inc. 48
Chapter 2 Summary Questions What are the 4 main functions of a computer? What is the difference between data and information? What are bits and bytes, and how are they measured? What devices do you use to get data into the computer? What devices do you use to get information out of the computer? What s on the motherboard? Where are programs and information stored? How are devices connected to the computer? How do you set up your computer to avoid strain and injury? 49