Low-Cost Rotating Memories: Status and Future

The first six years of the seventies have been a period of rapid developments in the field of rotating memory. Innovation has dominated the gamut of disk drive applications. For example, substantial inroads have been made by flexible disks into the low-entry-cost area where rotating memory was previously not competitive. Cartridge disk drives have gained dramatically in capacity and performance while prices have remained relatively steady. The announcement of the IBM 3340, Winchester, brought to the marketplace the concept of a pack with its own captive heads in order to obtain large capacity at modest cost by increased surface storage density. The IBM System 32 brought the concept of the "disk enclosure" which treats a substantial part of a disk system as a field replaceable component. Independent disk manufacturers have responded to the latter two IBM developments with their versions of modest-cost, high-capacity, replaceable media drives and with very low cost, fixed-disk systems.