Week Six Notes

Announcements

• I'll try again to hand back quizzes. Grades are posted.
• The first article review is due Monday 10/09
• We have a holiday Wednesday 10/11
• The first spreadsheet assignment is due Monday 10/16, so I will demonstrate technique on Monday, 10/09.
• We are doing 'self-service' roll call today. Please mark the appropriate box with an 'X'. Please tell me if your name is missing from the sheet.
• We are reading chapters three and four this week.
• It now appears I will be away on jury duty October 25 and 27. I think I'll have someone to substitute for me on both days.
• Hardware Demo with Power Macintosh G3 (Blue & White)
  Picture of Back

Chapter Three -- Hardware Basics - Peripherals

• OCR technology
• Discuss the difference between analog and digital images and videos.
• Digital versus Analog technologies
• Lossless and lossy compression technologies
• speech recognition
• Output Peripherals:
  • Monitors
    • Size measured in inches diagonally
    • Displays are composed of million of tiny dots: pixels (meaning Picture Element)
    • The resolution of a screen or printed area is measured in pixels per square inch, dots per (linear) inch (dpi), or dimensions of the screen in pixels. The more pixels you pack into a small area, the sharper, clearer, and better the image.
    • Color depth is important too - the number of different shades of color each pixel is able to take on.
    • Often the display is "driven" by a video adaptor plugged into the system bus. Typically there is memory-mapped VRAM on the adaptor. The CPU writes "values" to certain memory addresses that appear to be in the primary memory - but they are in the VRAM, and the "values" cause a pixel to light up with a certain color value. LCD screens typically have red, green, and blue sub-pixels.
  • Printers
    • Line printers - impact - character only
    • Dot matrix printers - impact - text & graphics
    • Laserprinters - nonimpact - fast & high quality - color is possible but expensive - resolution in the 600 dpi range.
    • Inkjet printers - nonimpact - slower - quality good - color is easy - cost is low - small & light - resolution in the 600 dpi range
    • Matching printed images to screen images is difficult - additive versus subtractive color - also screens produce light but printed images do not.
  • Plotters
• Other Peripherals:
  • Fax modem - "scans" a file and then transmits the "image file" over telephone lines.
  • Sound cards - accepts microphone input - outputs sound to speakers or headphones - performs digital sound to analog sound conversion - can synthesize sound (synthesizer)
  • " Robot arms, telephone switchboards, transportation devices, automated factory equipment, spacecraft ... " "force feedback joysticks, ... synthetic smells ... "
  • Tape Drives - cabable of both input and output - low cost per byte - sequential access only - very high speed - very high capacity - portable
  • Disk Drives - cabable of both input and output - direct access - low cost and high capacity rivals that of tape - may or may not be removable (portable).
  • zip disks, MD
  • Optical Disks - CD-ROM (read-only), CD-RW drives can read CD's and also burn CD-R and CD-RW disks. CD-R disks are WORM. CD-RW are erasable & rewritable
  • Solid State Memory Devices - erasable, non-volatile - flash memory in digital cameras - USB flash drives plug directly into universal serial bus (USB) ports - such a technology is expected to replace tape and hard disk eventually -
• Connection Modes:
  • serial port
  • parallel port
  • keyboard/mouse ports
  • video port
  • ports provided by expansion cards: modem, network
  • scsi connections for external devices
  • drive bays
  • firewire (IEEE 1394) ports for external devices - 400 Mbps (new Firewire 800 is twice as fast) - good for digital video - able to keep up
  • USB ports for external devices (USB 1 is 11 Mbps, USB 2 is 480 Mbps) - 126 devices possible in theory - hot swappable -
• A network of computers can share peripherals.
• Some 'peripherals' are connected directly to the network.
• Future Technology:
  • Tiny solid-state secondary storage
  • ultra thin, flexible, ultra high resolution displays
  • goggle displays
  • retinal displays
  • advanced digital sensors - eyes, ears, 'sense organs'