History (1951): Rabinow Patents Magnetic Disk Storage

This article comes from the Computer History Museum.

1951: Rabinow patents magnetic disk storage
NBS researcher’s notched disk memory informs the RAMAC design

Notched-Disk Magnetic Memory Device (c.1951)
(Courtesy of the National Institute of Standards and Technology)

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 disks as used by Poulsen in 1898. An inductive magnetic R/W 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 R/W 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 Rabinow’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 HDD drive in 1956.