1951: Rabinow patents magnetic disk data storage

NBS researcher‘s notched disk memory informs the RAMAC design

Russian immigrant Jacob Rabinow, a prolific inventor at the National Bureau of Standards (NBS), served as a consultant on computer development services for government agencies. Asked to a design a machine to record on and read from sheets of magnetic material, he instead proposed adopting discs as used by Poulsen in 1898. An inductive magnetic read/write head moved in the space between the disks that were mounted on a spindle.

In 1949 Rabinow built an experimental model of his disk-based storage unit. Each disk on the machine had a pie section, called a notch, removed. This allowed the read/write head to be moved from one disk to another. Approximately 18 inches in diameter, each disk held about 500,000 bits of data. The prototype machine, called a Notched-Disk Magnetic Memory Device, is on display in the Rabinow Room at the National Institute of Standards and Technology (NIST), Gaithersburg, MD. In 1951 he filed a patent for a “Magnetic Memory Device” that was granted in 1954. NBS policy was that inventions made as part of an employee’s job belonged to the government. As foreign rights remained with the inventor, Rabinow received patents in several foreign countries and sold non-U.S. rights to Remington-Rand for $15,000. Remington-Rand never used the patent.

Seeking a better method than punched cards, magnetic drums, or tape to store and access information, Reynold Johnson’s team at IBM in San Jose, CA included a description of Rainbow’s device in a 1953 report on “A Proposal for Rapid Random Access File.” They adopted the disk concept as the basis for the RAMAC project that yielded the first commercial hard disk drive in 1956.

  • Rabinow, J. “The Notched-Disk Memory” Electrical Engineering (August 1952) p. 745-9
  • Rabinow, Jacob. “Magnetic Memory Device” U.S. Patent 2,690,913 (Filed March 14, 1951 Issued: October 5, 1954)
  • Critchlow, A. J. “A Proposal for Rapid Random Access File” IBM Internal Report (February 6, 1953)
  • Rabinow, J. Inventing for Fun and Profit, San Francisco Press, San Francisco (1989)
  • Stevens, Louis D. “Data Storage on Hard Magnetic Disks” in Eric D Daniel, C. Denis Mee, Mark H. Clark eds. Magnetic Recording: The First 100 Years, IEEE Press (1999) p. 274
  • “Jacob Rabinow interviewed by Richard Mertz” Computer Oral History Collection, National Museum of American History (November 23, 1970) [Retrieved on 8.2.15 from: amhistory.si.edu/archives/AC0196_rabi701123.pdf]

File name: 1951_Disk_v5
Rev: 6.9.17