Anatomy of a disk


Stack of magnetic platters
Rotate together on a central spindle @3,600-15,000 RPM
Drives speed drifts slowly over time
Can't predict rotational position after 100-200 revolutions
Disk arm assembly
Arms rotate around pivot, all move together
Pivot offers some resistance to linear shocks
Arms contain disk heads--one for each recording surface
Heads read and write data to platters