Brains to Bytes:
The Evolution of Information Storage

February 8, 2002 - May 27, 2002

The Technology of Storage
Pre-classical period
Classical period
Industrial Revolution
Computer age
The future
Timeline for storage technology


Ever since human cultures have existed, people have needed to store and share information. Arguably, the first information storage device was biological: Memorized data in a person's brain. Memory is neither reliable nor long term, and retained information is available only to the memorizer and those within speaking distance. Other methods were needed. As you explore this exhibit, consider the implications and impact of storage devices and technologies on you and those who came before.

By 20,000 BC, primitive cultures had developed methods of storing information mechanically. By notching a stick, knotting a string, weaving a pattern, or carving or painting images in rock, information could be stored by one person for transmission to others or recall at some later time. The stored information had to be readable by a knowledgeable human being, but could be graphic images, patterns or symbols representing sounds or abstract concepts. Stonehenge is, possibly, one of the most monumental examples of data storage, as some believe its design stores information about astronomical phenomena. Other archaeologists believe that certain markings on the Nazca plain in Peru have a similar function. Storage technologies seem to have incredible longevity-we still record information with paint, sculpted stone, and carved wood (or cast in concrete).

As civilizations evolved, pictorial markings became more closely related to spoken language. In time, pictorial representations of sounds were replaced by alphabetic representations, a development that increased the percentage of literate citizens and facilitated communications between disparate groups. The ability to store information as symbols representing sounds, rather than as pictures representing concepts, was a major transition point in improving communications and storage efficiency.

Storage technology evolved to allow the creation of text or images on various substrate materials, including clay or stone tablets, skins, papyrus and metal plates. Both text and graphic representations were stored in this manner. The cuneiform tablets of the Babylonians (often used for accounting records), Egyptian hieroglyphics, Chinese/Japanese Kanji characters and western style alphabetic text are all examples of information storage in the classical period. Computing devices of the period, such as the abacus, employed the movement of counters, whose positions represented stored data. This is a type of volatile memory; the information was not intended for permanent storage, needing to be retained only while a particular computation was in process.

The technology of information communication is closely related to that of information storage. In the case of written material, the vehicle of transmission is also the vehicle for storage. In some cases, information was encrypted or sent by non-written means for security or for reason of immediacy. Ancient soldiers used burnished metal shields to reflect the sun as a signaling method. Fire beacons, smoke signals, lantern flashes and other methods were used to send encoded information. But there was no mechanical method to encode or decode a complex message, although the Romans did use a simple form of mechanical encoding/decoding. In most cases, the encryption/decryption steps had to be done by people.

The next major step in the development of information storage was printing. For the first time, mechanical methods could replace the individual scribe or artist in the creation of a record, greatly expanding the ability to record and distribute information. Printing represents another major transition point, again expanding the spread and ease of access to information. While the Gutenberg press is commonly thought to represent the first use of movable type, clay, wood and brass type were used in China and Korea several hundred years earlier. But printing still required human interpretation of the recorded information and human labor to create the required materials and the printed sheets.

As the industrial revolution dawned, owners of machinery began to find it useful to store information in ways that a machine could use directly. In some cases, the information could be stored as patterns. The studded cylinder or disk of a music box is an example of pattern stored data interpreted by a machine, in this case to reproduce music. Modern technologists would define it as a read-only memory: The data can be stored and read, but not altered thereafter.

The Jacquard Loom, which used punched cards to control the patterns the machine wove, is an example of information storage used to control machine operation, a precursor of today's automated production equipment.

Industrialization drove information storage technology. Improved ability to machine fine parts allowed the construction of mechanical calculators, in which the program that drove the device was incorporated into the designs of the wheels, cogs and levers used to construct it. This principle was also embodied in cryptographic equipment used through the end of the WWII period. Some of these devices, such as the Babbage Difference Engine, were first attempts to construct useful digital computers. In other cases, the shapes of cams were used to represent mathematical functions for use in mechanical mathematical computers, such as the differential analyzer. These were also in use through the WWII period, often to compute artillery shell trajectories, torpedo tracking solutions and other military uses.

By the end of the 19th century, information storage had made a number of advances. Audio was being stored as patterns of vibrations carved or etched into the surface of a rotating cylinder or disk. Images were being stored on film, with still images appearing in the early part of the century and motion pictures in the latter part.

The typewriter, which appeared in 1873, was a major influence on information storage, replacing time-consuming handwriting with a fast mechanical process. No less important was the elimination of a need for fine handwriting as a pre-requisite to a business career. The typewriter vastly expanded the clerical labor pool.

Hermann Hollerith devised a punched card based system for recording, storing and accumulating data. The Hollerith punched data card was used to store census data late in the 19th century, and punched cards or paper tape were the primary means of machine storage of data until well after World War II. Hollerith's Tabulating Card Company morphed into IBM in 1924. And electrical communication by telegraph and telephone created a demand for efficient methods to store, retrieve and communicate information.

Punched paper tape and magnetic recording both began in the 19th century. In 1898, Valdemar Poulson patented the first magnetic recording device, a magnetic wire recorder, foreshadowing the appearance of magnetic tape and disk drives before an additional half century had passed. Information storage media now could be writable by machine and readable by machine. If the media could be reused, reducing storage costs, so much the better. And magnetic storage is inherently rewritable and reusable. Another major transition point had arrived.

In the first half of the 20th century, punched cards, punched paper tape, and other mechanically marked media were widely used to store information. Card punch machines and readers, ticker tape machines, teletypes are all examples. Magnetic tape, used to record audio, was in use by the 1930s and also appeared in movie equipment as a way to record a synchronized sound track.

In the 1940s and 1950s, the invention of the transistor and the development of the stored program digital computer began to change the methods and uses of information storage.

To understand the role of information storage in a computer, it is necessary to appreciate that the computer uses several kinds of storage devices, each for a different purpose. These can be categorized as:

  • Main memory, used for immediate computational purposes. This memory is optimized for high performance and extremely fast access to and from the computer's processing elements, and is physically closely associated with the processing elements.
  • Secondary, or mass memory, used to store information to be used in or resulting from the computation process. The priority is for large amounts of storage capacity, moderate performance and lower cost. Secondary memory may be fixed or removable, depending upon the application.
  • Tertiary, or archival memory, used to store information that is not immediately required, but is useful or necessary to retain in the long term. Performance can be relatively slow, but storage capacity requirements are very large and the cost per unit of storage must be very low. Storage of this type often uses removable forms of media.
The storage technology used to satisfy these needs is different in each case, depending upon the needs of the system and its applications. In each case, the information stored can be either instructions for the computational process (stored program) or the data used/generated in the computational process.

Main memory has evolved from the use of mechanical elements to the use of electronic elements, notably semiconductor memory, which is now fast and inexpensive. Important steps along the way include magnetic core memory, delay line memory, and even some attempts to use mechanical memories such as rotating drums.

Secondary memory has employed magnetic tape, magnetic drums, magnetic disks, and optical disks, evolving from punched paper media. Examples include reel tape, cassette tape, floppy disks, semiconductor memory, rigid magnetic disks, CD-ROM and DVD disks.

Archival memory has employed magnetic tape drives, evolving from punched paper tape and decks of punched cards. Optical disks are also used. And printed paper is still the most widely used form of archival memory.

The technology of information storage is sophisticated and advanced, requiring extremes in reliability and performance from both mechanical, electronic and recording elements. Mechanics, chemistry, physics, software, system design and human design factors are all embedded in today's storage devices. Storage technology has migrated from the world of entertainment to the world of mathematics to the world of industry and back again, rapidly improving all the while. The first disk drive held 5 megabytes (5 million characters) and was the size of a very large refrigerator. Today you can pack a gigabyte (one billion characters) of information onto a disk drive small enough to fit into a handheld camera. Small semiconductor based cards used to store photographic data commonly hold over 50 megabytes of data. Even personal computers commonly contain 128 megabytes of fast semiconductor memory. Movies and music are contained on thin, inexpensive optical disks containing up to several gigabytes of data.

And it all will continue to get faster, cheaper and better.

Within the next ten years, it is possible that we will reach the limits of what can be accomplished using magnetic storage technology. Waiting in the wings are advanced optical storage techniques and, ultimately, the ability to store information by manipulating individual atoms, a technique already demonstrated in the lab, but far from a practical reality.

Incidentally, Hal the computer has little to fear from problems with his information storage in the future. It will be incredibly fast, incredibly large, and incredibly inexpensive. But he (and we) better watch out for those software bugs!


Books and publications

Magnetic Recording: The First 100 Years: Edited by C. Denis Mee, Eric D. Daniel, and Mark H. ClarkJohn Wiley & Sons, Inc., 1999

We, the Navigators: The Ancient Art of Landfinding in the Pacific: David Lewis
University of Hawaii Press,
Honolulu, 1994

Web sites

Computer History Museum A repository of computing technology from the dawn of the computing age to the present.

IBM storage research A summary of storage related research programs within IBM.

Jacquard loom

Magnetic Disk Heritage Center Papers and links concerning the early days of the disk drive industry

Magnetic Tape A history of magnetic tape recording

MouseSite: All about the the computer mouse and ways we interact with a computer.

Music Animation Machine Stephan Malinowski's animated musical scores - a new way of storing and visualizing music.

Optical data storage

Paper and paper making

Photography The American Museum of Photography process primer

Punched Cards University of Iowa site with technology and history of punch cards

Punched paper tape

Quipu: An Incan Mystery How Inca quipus are made and read.

Typesetting A Capsule History of Typesetting

Credits and Acknowledgements

The Museum of American Heritage expresses its thanks to the following individuals and organizations that designed and supported "Brains to Bytes" with time, artifact loans, financial gifts and enthusiasm.

Apple Computer
Gwendolyn Bell
Computer History Museum
Freeman Reports
Dr. A. S. Hoagland, Institute for Information Storage Technology, Santa Clara University
Jim Lyons
Pioneer Electronic Corp.
James N. Porter, President, DISK/TREND, Inc.
Monroe Postman

And special thanks to MOAH's Exhibits Committee

Bill Wehrend, Chair
Sue Beaver
Dick Clark
Andrea El-Danasouri
John Grant
Bob Katzive
Isabel Kennedy
Tom McFayden
Kim Pack
Beryl Self

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