A QUARTER CENTURY OF DISK FILE INNOVATION

This paper traces the development of disk file technology from the first disk drive to the present. A number of innovative advances are reviewed in the evolution of mechanical design, materials, and processes. These advances constitute the technological base that has permitted almost four orders of magnitude of improvement in areal density; they are discussed from four interrelated aspects: the magnetic head and its air bearing support; the head positioning actuator; the disk substrate and its magnetic coating; and the read/write signal detection and clocking electronics.