Computer Basics

Link to Storage 6 - Storage: Accessing Data

Link to Home - Jan's Illustrated Computer Literacy 101


Accessing Data

The process of accessing data has 4 steps.
1.  Seek
2.  Rotate
3.  Settle
4.  Data transfer

Step Measured as: Click to start and stop animations
1. seek
move the head to proper track
seek time
(ms)
read/write head seeks track
2. rotate
rotate disk under the head to the correct sector
rotational delay
(ms)
disk rotates under head
3. settle
head lowers to disk;
wait for vibrations from moving to stop
(actually touches only on floppies)
settling time
(ms)
head settles toward disk
4. data transfer  
 
copy data to main memory
data transfer rate
(kbs)
data is transferred

where ms stands for millisecond = .001 second and kbs is kilobytes per second.


Where you are:
JegsWorks > Lessons > Computer Basics


  1. Computer TypesArrow: Subtopics
  2. ApplicationsArrow: Subtopics   
  3. InputArrow: Subtopics
  4. ProcessingArrow: Subtopics  
  5. OutputArrow: Subtopics
Link to Storage 6. Storage Arrow: Subtopics list open 
    Intro
    Magnetic Disks
    Disk Format
    Disk Capacity
    Accessing Data
    Caring for Disks
    Caring for Data
    Magnetic Tape
    Optical Disks
    Other Devices
    Quiz
  7. Computer to ComputerArrow: Subtopics
  8. System SoftwareArrow: Subtopics
  9. ProgrammingArrow: Subtopics

  10. What You SeeArrow: Subtopics
  11. Hands On!Arrow: Subtopics
  12. On Your OwnArrow: Subtopics

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Glossary

Appendix


Total time to transfer a kilobyte:

for floppies,175 - 300 ms
for hard drive,15 - 80 ms
    new hard drives,       
   (Jan. 2000)
.0146 ms   (66.6 MB per sec).
This is seriously fast!!

Clearly, getting data from a hard disk is immensely faster than from a floppy.


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Last updated: 22 Jan 2008