Output and Storage Chapter 3 of Computers: Understanding Technology 1Bill Pegram - September 15, 2009

Types of Output Text Graphics Audio Video Bill Pegram - September 15, 20092

Output Devices Monitors Screen projector Printers Plotters Televisions Speakers Bill Pegram - September 15, 20093

Monitors Sizes are measured diagonally – 15, 17, 19, and 21 inches for desktop PCs Cathode ray tube (CRT) monitors utilize the same technology used in television sets Monitor screen consists of dots of phosphor material, with each dot containing a red, green, and blue phosphor 4Bill Pegram - September 15, 2009

CRT Technology Electron beam moves back and forth across the rear of the screen causing the dots on the front of the screen to glow Graphics card (video adapter) inside computer converts digital signals in computer to analog signals and sends them to the monitor 5Bill Pegram - September 15, 2009

Liquid Crystal Display (LCD) LCD monitors utilize digital signals Liquid crystals are sandwiched between two sheets of material. Electric current causes these crystals to twist, which blocks some light waves. Notebook computer LCDs use either passive matrix or active-matrix displays. The latter permit viewing from any angle. 6Bill Pegram - September 15, 2009

LCD Advantages over CRT Thinner (7” vs 17”) Lighter (12 lbs. vs lbs) Larger viewable screen size (17” vs. 16”) for same size Consume less power Generate less heat Flicker-free *Comparing 2 17” monitors on May 28, 2007 on Best Buy website 7Bill Pegram - September 15, 2009

CRT Advantages over LCD Less expensive ($115 vs. $ )* Precise color matching Blur-free movement Can adjust screen resolutions without affecting image sharpness whereas LCDs best at the native screen size** Price comparison of 17” monitors – Best Buy website, May 28, 2007 ** Monitor Guide on Best Buy website 8Bill Pegram - September 15, 2009

Screen Resolution, Dot Pitch 640x480, 800x600, 1024x768, etc. screen resolution (in pixels) Can be changed in Control Panel>Display The higher the resolution, the smaller something will appear Dot pitch: the distance between the centers of pixels on a display – lower values are better (values range from mm) 9Bill Pegram - September 15, 2009

Refresh Rate Refresh rate should be at least 72 hertz to avoid flicker 10Bill Pegram - September 15, 2009

Screen Projectors Screen projectors display what is displayed on the computer monitor on a large screen Used in classrooms and speakers making presentations at meetings, conventions, conferences, etc. 11Bill Pegram - September 15, 2009

Printers Printers can usually print in both portrait and landscape format Dot-matrix printers are impact printers; print head strikes an inked ribbon; impact printers are useful for making copies or Braille output The number of dots per linear inch is a measure of print quality – draft quality (~300 dpi) and letter quality (~1200 dpi) Line printers print an entire line at one time, utilizing a chain of rotating characters. These printers typically use 11 x 17 inch, tractor-fed, continuous-form paper. A fast printer can print 3000 lines per minute 12Bill Pegram - September 15, 2009

Printers (cont.) Ink-jet printers are non-impact printers and provide greater resolution than dot-matrix printers – spray tiny droplets of electrically charged ink – typically use a cartridge for black and one or more for color printing Laser printers are nonimpact printers that utilizes technology similar to photocopy machines 13Bill Pegram - September 15, 2009

Ink-Jet vs. Laser Printer Comparison Ink jet advantages –Printers less expensive, particularly for color –Print cartridges less expensive Laser printer advantages –Faster –Ink (toner) costs per page less than ink jet 14Bill Pegram - September 15, 2009

Other output devices Thermal printers – used in some fax machines, thermal dye transfer printer can do very high quality Plotters – maps, diagrams, charts Fax/modem card Speakers Speaker headsets Synthesized human speech 15Bill Pegram - September 15, 2009

Storage Devices and Media Devices are the hardware component which houses the medium on which data is recorded (e.g. VCR is the device, VCR tape is the medium) Speed of storage device measured by access time (to locate file) and data transfer rate Magnetic storage devices – floppy disks, hard disks, zip disks, tape cartridges, USB flash drives 16Bill Pegram - September 15, 2009

Floppy Disks and Disk Drives Track: numbered concentric circle Sector: numbered section of disk, similar to slice of pie Cluster: Group of sectors; the smallest unit of storage that is assigned a memory address File Allocation Table (FAT) – name of each file, its size, and the sector in which it begins Both floppy and hard disks spin, but floppy disk only spin when data is being accessed or stored 17Bill Pegram - September 15, 2009

Zip Disks Zip disks initially had 100MB capacity, then 250 and later 750MB versions introduced Introduced in 1994 by Iomega, the drive was $200 and each 100MB disk was $20; prices declined over time Have completely been replaced by writable CDs and flash drives 18Bill Pegram - September 15, 2009

USB Flash Drive Also known as jump drive, thumb drive, and pen drive Electronic with no moving parts (unless floppy or hard drive) 19Bill Pegram - September 15, 2009

Tape Cartridges and Tape Drives Magnetic tape was one of the first types of secondary storage for computers Tape storage is appropriate for storing large amounts of data that are no longer actively used but need to be saved for historical purposes Tape cartridges are used with personal computers to back up the contents of a hard drive 20Bill Pegram - September 15, 2009

Optical Storage Devices Compact Discs (CDs) and Digital versatile (or video) discs (DVD’s) are both 4.75” in diameter and about 1/20” thick Lasers are used to write and read discs; light is reflected from the nonburned areas (0) but not from burned areas (1’s) Unlike floppy and hard disks, which store data in concentric circles, optical disk data is usually stored in a single track which spirals from the center of the disk to the outer edge Some are rewritable and some are not – the designation of R means it can only be written to once, whereas RW means it is is rewritable 21Bill Pegram - September 15, 2009

CD, DVD Capabilities Data transfer rates for CDs expressed as multiple of speed of first drive (150KB/second) CD – 700MB capacity DVD – from 4.7GB to 17GB (double sided, double layered) capacity 22Bill Pegram - September 15, 2009