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STARS-Proposal:Magnetic Computer Storage

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Emerson W. Pugh


1945 ENIAC begins first test runs at the University of Pennsylvania
1948 Deliveries begin of IBM 604 Electronic Calculating Punch
1951 First UNIVAC is accepted by the U. S. Census Bureau
1952 IBM establishes laboratory in San Jose, California
1952 National Bureau of Standards researcher describes notched-disk magnetic memory
1953 Magnetic disk storage development becomes focus of IBM San Jose Laboratory
1955 First engineering prototype disk storage unit is operational in January
1956 First customer delivery of disk storage as part of a RAMAC engineering prototype
1957 Deliveries begin of IBM 305 RAMAC with production models of IBM 350 disk storage
1961 IBM announces 1301 Disk Storage product with slider technology
1962 IBM announces 1311 Disk Storage Drive with removable disk packs


Development of the world’s first magnetic disk storage product began in the IBM Laboratory in San Jose, California in 1952, the same year in which the laboratory was established. The purpose of the project was to devise a means for storing large quantities of data in a manner that could be accessed rapidly, even in a non-sequential manner, for analysis by electronic equipment that became available after World War II. Thousands of IBM 604 electronic calculators were delivered for use with punched card equipment beginning in 1948. Even more important in the long run were electronic stored program computers.

The first UNIVAC was accepted by the U. S. Census Bureau in 1951 and the first IBM 701 was shipped to a customer in 1953. Both of these computers used electronic vacuum-tube circuits to process data as commanded by instructions, which together with data were stored in high-speed memory. The most difficult engineering challenge had been to create memories with sufficient speed and reliability to keep up with electronic circuits of the computer. The memory of UNIVAC used mercury delay-line technology and that of the IBM 701 used cathode-ray-tube technology. Within a few years, both of these memory technologies were replaced by ferrite-core memories, which were faster, more reliable, and less expensive.

Much larger quantities of information and instructions for computers were stored in punched cards and on magnetic tape. Reading data and instructions from punched cards used relatively slow electromechanical equipment. Magnetic tape provided more rapid reading and writing, but only for sequential information transfers. Providing a superior means for storing and transferring large quantities of information to and from electronic stored-program computers was ultimately the major success of magnetic disk storage. As this article reveals, the problem that drove the initial development of magnetic disk storage came from the earlier era of data processing with punched card equipment.

The essay will describe the management philosophy in the new IBM laboratory and early efforts to define the laboratory’s development objectives. It will discuss the impact on those efforts of work begun in 1950 in the IBM Endicott, New York, laboratory on an electronic calculator with a rotating magnetic drum memory as well as work begun at about the same time at the National Bureaus of Standards on a novel notched-disk memory. The essay will reveal how market pressures and technical realities in 1953 caused the manager of the IBM San Jose Laboratory to select development of magnetic disk storage as the laboratory’s primary objective.

Emphasis will be given to the development of the first practical disk storage unit, which was used on RAMAC and delivered to customers beginning in 1956. A few early improvements to the technology used on RAMAC will be mentioned. These are described as the beginnings of a long string of improvements that permitted magnetic disk storage technology to remain in balance with semiconductor integrated circuit technology for many decades – decades during which both technologies experienced exponential rates of cost-performance improvement.


References of Historical Significance

Jacob Rabinow. 1952. “The Notched-Disk Memory,” Electrical Engineering, August 1952, p. 745-749. 

Trigg Noyes and Wesley E. Dickinson. 1952. “Engineering Design of a Magnetic-Disk Random-Access Memory,” Proceedings of the Western Joint Computer Conference, February 1952, p. 42-44. 

References for Further Reading

Charles J. Bashe, Lyle R. Johnson, John H. Palmer, and Emerson W. Pugh. 1986. IBM’s Early Computers (Cambridge, MA: The MIT Press, 1986), Chapter 8. 

Albert S. Hoagland. 2005. Early History & A 50 Year Perspective on Magnetic Disk Storage (28 February 2005),, accessed 20 August 2012. 

Louis D. Stevens. 1998. “Data Storage on Hard Magnetic Disks,” Chapter 18 in Eric D. Daniel, C. Denis Mee, and Mark H. Clark, Magnetic Recording: The First 100 Years (Piscataway, NJ: IEEE Press, 1998), p. 270-299. 

About the Author(s)

Emerson W. Pugh is the author or coauthor of four books on the history of IBM and the computer industry. He has a PhD in physics from Carnegie Mellon University and worked for IBM for 36 years in many capacities, including research scientist, product development manager, and corporate executive. He served as president of the IEEE in 1989, chair of the IEEE History Committee in 1996 through 1998, and president of the IEEE Foundation in 2000 through 2004.