IBM's First Hard Drive

How IBM Invented the Hard Drive in 1956

In 1956, IBM introduced a revolutionary device that changed the way data was stored and accessed. It was the first hard drive, a magnetic disk storage unit that could store millions of characters of digital data on rotating disks and access them randomly by movable heads. The hard drive was part of the IBM 305 RAMAC computer system, which was designed for business applications that required real-time processing of large amounts of data.

The hard drive, also known as the IBM 350 disk storage unit, was a huge and heavy machine that weighed over a ton and measured 5 feet high by 6 feet wide. It consisted of 50 disks that were 24 inches in diameter and had 100 tracks each. The disks spun at 1200 revolutions per minute and could store up to 5 million 6-bit characters, which is equivalent to 3.75 megabytes of data. The hard drive required a separate air compressor to operate and had to be transported by a forklift truck.

The hard drive had an access time of less than one second, which was much faster than the previous methods of data storage, such as punched cards and magnetic tape. The data could be read and written by two pairs of heads that moved up and down and in and out across the disk surfaces. The hard drive was leased for $750 per month, which was equivalent to about $7,000 in today’s money.

The first customer to receive the hard drive was Zellerbach Paper Company in San Francisco, in June 1956. The first production unit was shipped to United Airlines in Denver, Colorado, in November 1957. The hard drive was a huge success and paved the way for the development of more advanced and compact disk drives in the following decades. IBM continued to improve its hard disk technology and introduced several new models with increased capacity and performance.

The IBM hard drive in 1956 was a groundbreaking invention that revolutionized the field of data storage. It was the first device that could store digital data on magnetic disks that rotated at high speed and could be accessed randomly by movable heads. It was a milestone in the history of computing and information technology.