The first hard drive was introduced by IBM in 1953 and comprised of a massive 50 x 24-inch platters to give only 3.75 megabytes of data – that's less than a photo taken on a modern smartphone. 

The IBM 350 Disk File as it was known was the first ever ‘Random Access File’ having a rapid random access at low rental cost, namely $3200 a month. The value of the unit was estimated at $50,000 or $11,364 per megabyte!

The engineers had considered a number of other technologies before deciding on the hard disk drive. Commercial use began in 1956 with the IBM 305 RAMAC and the hard drives were only usable in data centres with their climate controlled and protected environments.

The 24-inch platters spaced 3-inches apart were mounted in external enclosures about the size of a washing machine and required huge motors to spin the platters up to speed. A single head assembly with two read/write heads accessed both sides of each platter. To read a platter, they had to be unloaded manually and moved to the desired platter and track. The disks rotated at 1200RPM with twenty tracks to the inch and data densities of one hundred bits per inch. More than one thousand were built before production ended in 1961.

Used for commercial applications including inventory control, accounting and payroll, the operator had a console with punched card input and output. Used widely by the US Military, the IBM 305 RAMAC, the first was delivered to the Zellerback Paper Company in San Francisco. IBM’s press release in September 1956 stated "305 Ramac and 650 Ramac, two electronic data processing machines using IBM's random access memory, a stack of disks that stores millions of facts and figures less than a second from management's reach. Because transactions are processed as they occur, the fresh facts held in a random access memory show business as it is right now, not as it was hours or weeks ago.".