IBM System/360 and the Personal Computer Revolution

The Automobile Analogy and the Computer Revolution

Many inventions have changed the world: the automobile, the airplane, the telephone, and the computer. Each in its own way transformed how we live, how we work, and how we communicate. Yet technological revolutions are only possible once a new technology has been seamlessly integrated into everyday life. A product that is too difficult, or too expensive, for general use will remain a curiosity or a novelty, with little practical application.

The earliest cars were toys of the very wealthy. Made to order, they were costly to produce and difficult to maintain. There was no infrastructure to support them, paved roads were scarce, and gas stations did not exist. Owning and operating a car was almost like being a captain on the high seas — one needed to be entirely self-sufficient. Henry Ford, however, dramatically altered this situation. His use of the assembly line made possible the production of reasonably priced automobiles — motor-driven vehicles that could easily be purchased and used by the masses. The automobile revolution was under way.

The computer, too, promised to change our world beyond recognition. Its ability to perform complex mathematical calculations at high speed eliminated the need for thousands of hours of tedious work by human experts. The very first computers, invented in the 1940s, proved useful in wartime. Computations relating to the firing ability of large guns — computations that once took years — could be accomplished in hours or minutes. Enemy codes with millions of possible combinations could be deciphered in far less time than ever before. Victory in the Second World War owed much to this new technology, and it was the scientists and technicians of the International Business Machines Corporation, or IBM, who were responsible for the creation and maintenance of many of these machines. But a computer the size of an entire room, costing millions of dollars and requiring extensive training to operate, would be of little use to smaller organizations or individuals. IBM recognized the need for a computer that could be mass-produced, just as Ford had mass-produced automobiles. It was precisely this kind of visionary thinking that led to the development of the System/360, and later to the successful launch of the Personal Computer.

The IBM System/360: Mass Production and Open-Ended Design

First manufactured in 1964, the IBM System/360 marked the dawn of a new era in computing and in the wider world. Unlike earlier machines that had been produced individually and with unique specifications, the System/360 was born on an assembly line. By building thousands of identical machines, IBM could produce each unit for considerably less than it cost to manufacture a custom-made example. Furthermore, the System/360 was designed to perform a variety of different applications — applications that could find use across many different fields, organizations, and companies. The machine was also designed to evolve: to adapt to changing technologies and new demands. IBM called these dynamic new features "Open Ended Design."

The new design had to provide a dependable base for a decade of customer planning and customer programming, and for continuing laboratory developments, whether in technology, application and programming techniques, system configuration, or special requirements. Current trends had to be extrapolated and their consequences anticipated. This anticipation could be achieved by direct provision, but might also take the form of generalization of function.

Changing requirements for system configuration would demand a standard interface, as well as capabilities for a machine to directly sense, control, and respond to other equipment modules via paths outside the normal data routes. In many particular applications, some special — and often minor — modification enhances the utility of the system. These modifications, known as RPQs, might correct some shortsightedness of the original design and often embody operations not fully anticipated. In any event, a good general design would render certain modifications unnecessary and accommodate others.

The IBM System/360 was therefore the computing world's first look at a machine that could be used for a wide variety of purposes and that could be expected to grow and adapt to new situations and needs.

The System/360 and the Birth of the Software Industry

In particular, the IBM System/360 helped to create an independent market for computer software. As previously noted, the old made-to-order machines were designed for specific purposes and for those purposes only. In developing a computer designed to perform generalized functions, IBM needed to ensure that its customers could tailor the System/360 to their own particular needs. Separate application software would make it possible to modify a machine's capabilities, and it also made possible the establishment of a whole new industry devoted to producing specific, narrowly defined applications.

Companies other than IBM could now work together with IBM to develop software compatible with the computing giant's machines. Until the advent of the System/360, not only had each machine been unique, but each manufacturer had also made use of highly individualized operating systems. IBM's decision to begin "sharing" the System/360's operating systems opened up vast new markets and almost boundless possibilities.

Early commercial applications of computers were associated with in-house programming using higher-level languages; service bureaus provided an alternative source of computing services. This structure — in which computer manufacturers created tools for applications development, users developed applications software, and a residual of users employed service bureaus for their data processing needs — was short-lived. Developments between 1965 and 1970, including IBM's success with the System/360 and IBM's decision to unbundle software from its supply of computers, increased the market for multi-installation software sales. The new entrants that formed the base of the independent software vendor (ISV) industry included software tool and utility program suppliers, as well as "vertical market" software companies that provided applications for particular industries and for common needs such as accounting systems. For these reasons, 1965–1970 were the pivotal years in the emergence of the current structure of the U.S. software industry.

As can clearly be seen, the IBM System/360 revolutionized the computer industry and began the process of "computerizing" much of the rest of the world's major industries. Notwithstanding the System/360's success, it was still a mainframe computer, and as such remained out of reach for the average consumer — including many smaller companies, and even many larger ones without the profit margins to justify major investments in computing. To take computing to the next level, to make the computer truly ubiquitous, required the development of something entirely new: the Personal Computer.

Works Cited

Amdahl, G.M., Blaauw, G.A., and Brooks, Jr., F.P. "Architecture of the IBM System/360." IBM Journal of Research and Development, Vol. 44, No. 1/2, IBM, January/March 2000. [Reprint of IBM Journal of Research and Development, Vol. 8, No. 2, 1964.]

Anderson, Philip, and Michael L. Tushman. "Technological Discontinuities and Dominant Designs: A Cyclical Model of Technological Change." Administrative Science Quarterly 35.4 (1990): 604–633.

Campbell-Kelly, Martin, and William Aspray. Computer: A History of the Information Machine. New York: Basic Books, 1996.

Mowery, David C., ed. A Comparative Study of Industry Evolution and Structure. New York: Oxford, 1996.

Pool, Robert. Beyond Engineering: How Society Shapes Technology. New York: Oxford University Press, 1997.