The Computer History Museum (CHM) recently released six video-recorded oral histories of key engineers and scientists from Japan who made seminal contributions to the magnetic recording technologies used in hard disk drives.
Hard disk drives were invented by IBM in the United States in the mid-1950s and have formed the backbone of high-speed random access storage for over six decades: today’s hard disk drives share many of the same components—albeit greatly refined—as the first 1956 RAMAC disk drive from IBM. “The hard disk drive enabled real-time transaction processing and updating of information. Today we rely on hard disk drives to store nearly everything about ourselves,” said Dag Spicer, senior curator at CHM. But the journey from those early days to now relied on solving complex and hard-won technical challenges with new inventions from contributors around the world.
Japanese computer manufacturers Hitachi, Fujitsu, and NEC entered the market during the 1960s, and by the late 1970s, the Japanese government identified the hard disk drive market as strategically important. To advance its position, Japan’s Ministry of International Trade and Industry (MITI) encouraged the establishment of inter-company cooperation as well as joint industry-academic efforts in magnetic recording. The origins and development of these efforts resulted in breakthroughs that have become ubiquitous in all hard disk drives used today and are captured in this new oral history series.
The following six oral histories, conducted in Japan in 2016 by CHM’s Storage Special Interest Group (SIG), encompass the research, development, and initial commercialization of glass substrates, perpendicular magnetic recording (PMR) disk drives as well as PMR heads and disks, and MgO-based tunneling magnetoresistive (TMR) heads. Project participant and renowned industry scientist Chris Bajorek said, “I was pleased to have been part of the effort to interview key Japanese contributors to the advancement of magnetic recording technology and products. Their contributions have been adopted in all hard disk drives worldwide. I am especially thankful to Dr. Yoichiro Tanaka and Toshiba for their partnership in this project. They organized and hosted the visit to Japan. Dr. Tanaka also interviewed several of the individuals and was himself interviewed as well.”
Two of these oral histories were conducted in Japanese and the other four were conducted in English.
One of the most significant recent technology developments has been the commercialization of Perpendicular Magnetic Recording, or PMR. Starting in 2005, adoption of PMR facilitated a tenfold increase in the data capacity of Hard Disk Drives (HDDs). HDD capacities of 10 TB are the norm in 2017. Professor Shunichi Iwasaki, of Tohoku University, was the most important champion of PMR. He also made key PMR inventions. This oral history records the contributions Professor Iwasaki made to the success of PMR.
One of the most significant recent technology developments was the commercialization of perpendicular magnetic recording (PMR). Starting in 2005, the adoption of PMR facilitated a tenfold increase of data capacity in hard disk drives (HDDs). HDD capacities of up to 10 TB are the norm today. Researchers at Tohoku University made key contributions in the invention of PMR as well as in the understanding of the physics of PMR and requirements of heads and media. This oral history records the contributions of Professor Yoshihisa Nakamura and Hiroaki Muraoka to the success of PMR.
One of the most significant recent technology developments was the commercialization of perpendicular magnetic recording. Starting in 2005 adoption of perpendicular magnetic recording significantly facilitated an eight-fold increase of data capacity in hard disk drives. Hard disk drive capacities of up to 10 TB are the norm today. This breakthrough was made possible by use of a unique perpendicular magnetic recording medium, known as the oxide medium, first developed in Toshiba under the leadership of Dr. Yoichiro Tanaka.
The oxide medium was adopted by the entire hard disk drive industry. The first generation of this perpendicular magnetic recording disk was manufactured by Showa Denko. It was matched with a first generation perpendicular magnetic recording head supplied by TDK. This oral history records the three-way collaboration between these companies that resulted in Toshiba’s first PMR hard disk drive. The interview will include Messrs. Yoichiro Tanaka from Toshiba, Hiroshi Sakai from Showa and Koichi Terunuma from TDK.
This interview centers on the development of the MgO tunnel barrier used in modern TMR heads. Hard disk drives have survived as the information storage density device of choice because of sustained and steep advances in storage density. Density advances required downward scaling of key components. The reduction of the size of stored bits caused signal amplitude reduction which necessitated the invention of more powerful detectors. Magnetoresistive heads were the successful answer.
The third generation of MR heads introduced the phenomenon of tunneling to increase the change of resistance. The largest change of TMR head resistance has been achieved with the MgO tunnel barrier. This oral history records a history of the development of the polycrystalline MgO based magnetic tunnel junction and the contributions to its success by Messrs. Naoki Watanabe, Hiroki Maehara, Koichi Terunuma and Chang Man Park.
The advent of mobile computers in the 1990s required hard disk drives (HDDs) with much higher shock robustness than possible with aluminum-based media. Although, it is counterintuitive, only glass-based media using chemically strengthened glass met the shock resistance and cost requirements of this application. From the outset, Hoya led the industry in developing and supplying such glass substrates. This oral history records the history of Hoya’s contributions under the leadership of Mr. Isao Suzuki.
One of the most significant recent technology developments was the commercialization of perpendicular magnetic recording. Starting in 2005 perpendicular magnetic recording significantly facilitated a tenfold increase of data capacity in hard disk drives. Capacities of up to ten terabytes are the norm today. This breakthrough was made possible by use of a unique perpendicular magnetic recording medium known as the oxide medium which was first developed in Toshiba under the leadership of Dr. Yoichiro Tanaka. Dr. Tanaka’s team also integrated this oxide medium into the industry’s first perpendicular magnetic recording hard disk drive. This oral history records Dr. Tanaka’s contributions to these successes.
Since November, 2003, the Museum has been actively collecting materials related to the global storage industry. The Storage Special Interest Group (Storage SIG) Steering Committee leads this effort and is composed of volunteers who bring decades of industry experience and knowledge to the group’s work. SIG members come from disk, tape, and storage system company backgrounds, as well as from leading independent industry consultancies. Group members have conducted many oral histories of industry pioneers and written detailed histories of major events in the storage world. The Storage SIG works closely with the Museum’s curatorial staff to advise on the Museum’s strategic direction as it applies to computer storage. For more information about the Storage SIG, visit Storage Special Interest Group. For more information about storage history, visit The Storage Engine.
Oral histories bridge the gap between written historical record and individual experience. The Computer History Museum’s oral history program records and preserves the firsthand recollections of computing pioneers from around the world in their own voice, enriching scholarly research and adding new depth to the history of computing. For more information, visit, Oral History Collection.