Before magnetic disk storage was developed, running programs on early computers required search through miles of magnetic tape or stacks of coded punch cards, looking for the right data. Sometimes computer users would not see the results of the machine's ingestion of their "batch" cards for hours, even days.

The random-access magnetic disk drive changed all that. Retrieving data in hardly any time at all, the magnetic drive set the stage for the rapid succession of advances in computing that would follow. Magnetic disk storage would make saving work and calling it up again as simple as a few keystrokes or mouse-clicks. In recognition of this great leap forward, the IEEE Board of Directors has named the first commercially available magnetic disk drive an IEEE Milestone in Electrical and Computer Engineering.

The story of magnetic disk storage began in 1952, when IBM Corp., based on the East Coast of the United States, in New York City, decided to set up a small research laboratory on the West Coast. IBM chose San Jose, Calif., for the lab. It was midway between Los Angeles and Seattle, cities that were hubs of aircraft manufacturing, where IBM's intended customers could be found.

Given the job of managing the San Jose lab was Reynold B. Johnson, a former high-school science teacher (and the person honored when, in 1993, the IEEE Magnetics Society named its Reynold B. Johnson Information Storage Technology Field Award after him). Johnson was told that his lab could work on anything even remotely related to computers provided none of its projects duplicated work already under way at other IBM labs. Also, he could initially hire no more than 50 workers in the lab.

One of the San Jose lab's first research thrusts was the development of a data storage device and associated computer system that allowed transaction processing, a procedure that completed transactions as they occurred rather than crunching data in batches and completing them later. The first Random Access Method of Accounting and Control (RAMAC) prototype consisted of 51 memory disks coated with magnetic iron oxide paint—similar to the paint used on San Francisco's Golden GateBridge. The prototype could hold a grand total of 5 megabytes and its disks were mounted at 1.27-centimer intervals on a vertical shaft. A mechanical arm with a read/write head on each side could scan or record on the top and bottom of a disk simultaneously. The heads could move up or down to any of the 60-cm-diameter disks and then in or out to the desired track in less than a second. Perhaps most important, the new IBM 305 computer—a stand alone machine attached to the disk drive system—could access data randomly, an impossible task for magnetic tape or punched cards.

Within a few years, the San Jose lab produced a larger-capacity version of the RAMAC device that at US $35000 they figured was cheap enough to be commercially viable. IBM announced its new technology on 6 May 1955, and the first IBM RAMAC 305 system system with the 350 disk file hit the market more than a year later—on 4 September 1956. It could store 4.4 megabytes of data, and IBM leased the device for US$ 35 000 a year.

In recognition of the importance of magnetic disk storage, the RAMAC 305 system, and the 350C disk drive—to which the gigantic Google databases, the hard drives in the world's desktop and laptop computers, the wildly popular iPod music players, and the entire magnetic storage industry owe their start—the IEEE will present a plaque at a milestone dedication ceremony to be held in San Jose on 26 May. An associated milestone event will be held that same week at Santa Clara University, focusing on the RAMAC restoration project, which preserves original machinery and set up a display on magnetic technology development at the site of the IBM lab.

For more information, visit: http://www.ieee.org/organizations/history_center/ramac.html and for more information on RAMAC and the early history of magnetic disk storage, visit http://www.magneticdiskheritagecenter.org.