Head positioning servo and data channel for HDDs with multiple spindle speeds

For hard disk drives (HDDs) having multiple disk rotational speeds, a new data channel and head positioning servo system was developed. Head positioning performance at the low spin-speed was preserved by using a synchronous servo scheme with more servo areas than the conventional scheme. Using a common physical disk format, sufficient servo performance and the same data recording density of 1.3 Gbit/inch/sup 2/ were obtained on two 2.5 inch prototype HDDs with a low spin-speed of 37.5 Hz and a high spin-speed of 75 Hz. Disk interchangeability was also confirmed.