Computer Basics

6 - Storage: Accessing Data

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)
2. rotate rotate disk under the head to the correct sector	rotational delay (ms)
3. settle head lowers to disk; wait for vibrations from moving to stop (actually touches only on floppies)	settling time (ms)
4. data transfer     copy data to main memory	data transfer rate (kbs)

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

Total time to transfer a kilobyte:

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