IBM and the History of Random Access File

IBM in 1953 recognized the immediate application for what it termed a "Random Access File" having high capacity, rapid random access at a relatively low cost. After considering several alternative technologies such as wire matrices, rod arrays, drums, drum arrays, etc., the engineers at IBM San Jose invented the disk drive. The disk drive created a new level in the computer data hierarchy, then termed Random Access Storage but today known as secondary storage, less expensive and slower than main memory (then typically drums) but faster and more expensive than tape drives.The commercial usage of hard disk drives began in 1956 with the shipment of an IBM 305 RAMAC system including IBM Model 350 disk storage.