history of hard disk

In 1953 IBMrecognized the immediate application for what it termed a "Random Access File" having high capacity and rapid random access at a relatively low cost. [ 1 ]After considering technologies such as wire matrices, rod arrays, drums, drum arrays, etc., [ 1 ]the engineers at IBM's San Jose California laboratory invented the hard disk drive. [ 2 ]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. [ 3 ] The commercial usage ofhard disk drivesbegan in 1956 with the shipment of an IBM 305 RAMACsystem including IBM Model 350 disk storage. [ 4 ] US Patent 3,503,060issued March 24, 1970, and arising from the IBM RAMAC program is generally considered to be the fundamental patent for disk drives. [ 5 ] Each generation of disk drives replaced larger, more sensitive and more cumbersome devices. The earliest drives were usable only in the protected environment of a data center. Later generations progressively reached factories, offices and homes, eventually reaching ubiquity. Disk media diameterwas nominally 8 or 14 inches (200 or 360 mm) and were typically mounted in standalone boxes (resembling washing machines) or large equipment rack enclosures. Individual drives often required high-current ACpower due to the large motors required to spin the large disks. Hard disk drives were not commonly used with microcomputers until after 1980, when Seagate Technologyintroduced the ST-506, the first 5.25 inches (133 mm) drive. The capacity of hard drives has grown exponentially over time. When hard drives became available for personal computers, they offered 5- megabytecapacity. During the mid-1990s the typical hard disk drive for a PC had a capacity of about 1 gigabyte. [ 6 ]As of January 2012, desktop hard disk drives typically had a capacity of 500 to 2000 gigabytes, while the largest-capacity drives were 4 terabytes.