DSP use in hard disk drive position control

The first application of a digital signal processor (DSP) for hard disk drive position control occurred more than a decade ago in the high performance, high capacity and high cost class of disk drive products, motivated by the promise of higher performance accompanied by only a modest increase in relative cost compared to a comparable analog design. The transition from analog to digital position control for disk drives has followed the rapid decrease in cost for DSP chips and disk drive technology has been advanced as a result. This paper discusses the factors which led to the change from analog to digital position control and describes how DSP has improved drive position control performance since its introduction in the early 1980´s