Classes

Class Syllabus

Labs

Interact

Disks
Physical Media (Historically)
- Flip switches
- Relays
- Punch Tape
- Punch Cards
- Magnetic Tapes (see them in SciFi films)
- Magnetic Cards
- Magnetic Disks
- Hard disks
- Floppy disks
- Optical Disks
  - Worm (Write Once Read Many)
  - MO (magneto Optic)
- Sequential verus Random
  - Tapes are sequential access
  - Disks are random access
- Disks
  - Magnetic coating
  - Sectors
  - Tracks
  - Surfaces
  - Cylinder
  - Read/Write head
  - Arm
  - Spin rate (3600 - 10000 RPM)
  - Head float above surface (0.000001 inch)
    - smoke (0.00025 inch)
    - finger print
    - dust
    - hair (0.03 inch diameter)
  - Sealed Environment - A dust particle hitting at 7200 RPM is disasterous
  - Vibrations
  - Bouncing
  - Large capacity - but when something goes wrong......
- Floppy Disk drives
  - Slower/Removable
  - diskette = floppy
  - magnetic surface
    - tracks
    - 2 surfaces
    - smaller capacity
    - Slower
    - Removable
    - Portable
    - Head not as close, but dust/sand create problems
    - Initializing a floppy - putting the rule on paper
    - copy
    - erase