2/13: Storage, Input & Output Data storage Magnetic Optical Input & Output: Definitions Examples: Input & Output devices Keyboards Fonts Image File Size: Color Depth, Resolution Monitors

Data storage: what is it? Long-term storage, not immediate memory Not RAM (short-term memory) Synonyms: secondary storage, auxiliary storage, mass storage images courtesy of dalelabs.com,, iomega.com, imation.com,

Data storage: where is it? Storage involves 2 parts: the device & the media Removable vs. fixed media Where can you store data? magnetic media optical media magneto-optical media solid state media image courtesy of How Computers Work

Storage characteristics Random vs. sequential access Tracks & sectors Speed spin rate (RPM) seek time & latency access time data transfer rate Storage Capacity areal density size Image courtesy of How Computers Work

Magnetic data storage Use magnets to store bits: Reading and writing example: 0 = N , 1 = S Reading and writing Floppy disk drives Hard disk drives PACE image courtesy of How Computers Work

Floppy disk drives: types Low-density floppy drives: 5.25” floppy disks 3.5” 1.44 MB floppy disks High-density floppy drives: Zip disks, LS-120 disks Images courtesy of How Computers Work, Imation.com, and Iomega.com

Floppy disk drives: how they work Shutter opens with an arm. Cookie spins on the spindle. Read/write heads get close to the cookie inside Magnetic particles generate electric currents in the heads. Electric currents are interpreted as a series of bits. Images courtesy of How Computers Work

Hard disk drives: overview Glass platters coated with magnetic particles Read/write heads like floppy drives but much smaller Multiple platters, multiple heads. Image courtesy of How Computers Work

Optical Storage Instead of using magnetism to store bits, we use light A laser is the light Laser: “light amplification by stimulated emission of radiation” Extremely focused, narrow beam of powerful light Depending on the wavelength, the beam can be narrower or wider Lands are flat areas on the disc Reflect light like a mirror Pits are holes in the disc Scatter light Courtesy of http://www.microserve.net/~tpetchy/DVD.shtml

CD Drives: Types and Operation CD-ROM drive speeds: how many times faster than the original CD-ROM drives 2x, 4x, 6x, 8x, 16x, 32x, 48x Operation: Diode generates laser Laser bounces off mirrors, reaching the disc Disc reflects or scatters laser Light-sensing diode sees the reflections, comparing them to a timing circuit to generate 0s and 1s Image courtesy of c-cube.com

Types of Optical Discs Compact discs: CD-ROM: read only memory (680 MB) CD-R: Recordable (650 MB) CD-RW: ReWritable (495 MB) Image courtesy of c-cube.com

Types of Optical Discs Digital versatile discs – higher density storage DVD-ROM: read only memory (4.7 – 17 GB) DVD-R: Recordable (3.9 GB?) DVD-ram (5.2 GB) & DVD+RW (6.0 GB): Rewritable (still fighting) Image courtesy of c-cube.com

Input & Output: Definitions Input: “to enter data into the computer for processing; the data entered.” Output: “to transfer data from the computer to devices that allow you to see, hear, or feel it; the data transferred.” images courtesy of keytronic.com, viewsonic.com

What is the essential qualification? For something to be qualified as an input or output device, it must be an interface between the user and the computer. Cables, dial-up modems, etc. would NOT be input or output devices. images courtesy of logitech.com, viewsonic.com

Input devices: examples keyboards · fax modems pointing devices · scanners microphones images courtesy of logitech.com, keytronic.com, buy.com,

Output devices: examples monitors · printers speakers · feedback game controllers Images courtesy of viewsonic.com, yamaha.com, logitech.com

The Keys on the Keyboard for inputting text Standard keyboard alphanumeric keys function keys (F1) shift keys (left shift) toggle keys (caps lock) special function keys (enter, windows, menu, home, end, page up/down, delete, backspace, esc) You will be expected to know what the keys on the keyboard do. Image courtesy of fentek-ind.com

Ergonomic Keyboards Ergonomics: how machines and humans interact, with an emphasis on bodily stress and fatigue. Ergonomic keyboards are designed to alleviate wrist strain -- particularly carpal tunnel syndrome. images courtesy of fentek-ind.com and darwinkeyboards.com

F F Fonts Types of fonts: typeface family: Arial, Times Roman serifs: things on end of letters Types of fonts: style: regular, bold, italic, shadow size: measured in points (72 pts/in) F serifs F Arial, 208 pt., italic Times New Roman, 229 pt., regular

Image File Size: Contributors Original 56K Images are stored on a per-bit basis: Bigger the physical image = bigger the file size Deeper the color depth = bigger the file size Higher the resolution = bigger the file size Lower res 51K 8-bit color 35K 50% size 10K

Color Depth Color depth is the number of bits that are stored for each pixel 1-bit B&W line art halftone 8-bit grayscale 24-bit color 1 bit line art 1 bit halftone 8-bit grayscale 24-bit color Pictures appear courtesy of Mustek http://www.mustek.com.tw/Support/html/scannings.html

Why 24-bit Color? Color is stored as the combination of three colors: red, green, & blue (RGB). Each color has a value stored for it using 8 bits. 3 colors x 8 bits = 24 bits total. How many levels for each color can be recorded? 8 bits per color = 2 to the 8th power = ?

Resolution: Printers & Files resolution: dpi dots per linear inch horizontal resolution may differ from vertical resolution higher the resolution, the “truer” the image. monitors: 50-100 dpi printers (inkjet): 100-200 dpi printers (laser): 300-1200 dpi George Seurat, Sunday Afternoon on La Grande Jatte from Art.com

Resolution 300 dpi: no zoom, 400% zoom 150 dpi: no zoom, 400% zoom

How Monitors Work Resolution Refresh Rate Raster Flat-panel displays scan lines field Flat-panel displays                                                                                                                               image courtesy of sonystyle.com

How many colors are there? Name colors possible mode Standard VGA 16 4 bit 256 color mode 256 8 bit High Color 65,536 16 bit True Color 16,777,216 24 bit VGA: Video Graphics Array SVGA: Super VGA XGA: Extended Graphics Array

Terms Resolution: # pixels displayed horizontally and vertically Refresh rate: how quickly the image is redrawn

Raster scanning Raster: the area that is hit by the electron beams, line by line. Each line is called a scan line. Field: a complete sweep of the screen. Refresh: rate usually at least 60/sec (60 Hz)

Flat-panel LCD Displays Passive-matrix vs. Active-matrix Resolution limitations Considerably more expensive than CRTs image courtesy of Viewsonic.com

Flat-panel Plasma Displays Brighter than LCD Easier to manufacture (theoretically) Mainly used for large-scale applications image courtesy of Viewsonic.com