1. 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

2. 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,

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

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

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

17. 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

18. 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

19. 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

20. 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

21. 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

22. 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 = ?

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

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

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

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

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

28. 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)

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

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