Who Invented the Hard Drive?

Created on 11/12/2013 by .
Reynold B. Johnson, an American inventor, computer pioneer and a native of Minnesota who while working for IBM developed the first hard disk drive in 1956. Known as the IBM 305 RAMAC or 'Random Access Memory Accounting Machine', it had fifty 24-inch-diameter disks with a working capacity of 5 MB.

IBM 305 RAMAC Hard Drive Drawings & Images


US Patent #3,503,060

A magnetic disc drive for positioning a magnetic transducer in cooperative relationship with a selected one of a plurality of concentric ·circular recording tracks of a magnetic surface of a disc in response to an externally supplied track address signal. A motor rotates the disc about an axis at a constant speed. A loading means resiliently urges the transducer into transducing relation­ ship with said surface. A positioner responds to the track address signal for selectively positioning the transducer at the track designated by the track address signal by movement along a line extending radially of the axis and parallel to the magnetic surface of the disc.

Full patent details

Reynold B. Johnson Biography

In the early 1930s, Johnson, a high school science teacher in Michigan, invented an electronic test scoring machine that sensed pencil marks on a standardized form. IBM bought the rights to Reynold's invention and hired him as an engineer to work in their laboratory.

One of Reynold's early assignments was to develop technology that allowed cards marked with pencil marks to be converted into punched cards. That "mark sense" technology was widely used by businesses in the 40s, 50s, and 60s. The Federal Government used it under the name "electrographic" technology.

Johnson was working with Sony on another project when he developed the prototype for a half inch videocassette tape. Lou Stevens noted that Sony was using wider tape on reels. He cut the tape to a half an inch, and put it in a cartridge.

Johnson retired from IBM in 1971. He obtained more than 90 patents through out his life time.