History of hard disk drives
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.
Compared to modern disk drives, early hard disk drives were large, sensitive and cumbersome devices, more suited to use in the protected environment of a data center than in an industrial environment, office or home. Disk media was nominally 8-inch or 14-inch platters, which required large equipment rack enclosures. Drives with removable media resembled washing machines in size and often required high-current or a three-phase power supply due to the large motors they used. Hard disk drives were not commonly used with microcomputers until after 1980, when Seagate Technology introduced the ST-506, the first 5.25-inch hard drives, with a formatted capacity of 5 megabytes.
The capacity of hard drives has grown exponentially over time. With early personal computers, a drive with a 20 megabyte capacity was considered large. During the mid-1990s the typical hard disk drive for a PC had a capacity of about 1 GBAs of July 2010, desktop hard disk drives typically have a capacity of 500 to 1000 gigabytes, while the largest-capacity drives are 3 terabytes