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In January of 1972, Hewlett-Packard made a lot of engineers’ pockets happy.

On January 4, 1972, the first scientific pocket calculator, called the HP-35, was introduced by Hewlett-Packard. It would prove to be an historic debut.

Although a few hand-held calculators were introduced in 1971, the HP-35 could handle higher functions, including logarithms and trigonometric functions. The HP-35 was the first to use a four-register operational memory stack to store and retrieve intermediate answers, the first to provide stack control keys in order to display those intermediate results for further processing, and the first to employ reverse Polish notation for entering data into a calculator. The HP-35 was delivered with an addressable memory register so that constants could be entered and used on demand.

The HP-35 actually outperformed the mainframe computers of its day. Its calculations offered greater mathematical precision and were performed more quickly than calculations on the IBM 360.

HP Gets Giddy

The HP-35 was so successful that in just six months the June 1972 edition of the HP monthly magazine reported the following:

“For a company that has always dealt soberly with the business of its business, albeit with style and invention, Hewlett-Packard has discovered a whole new giddy interface, thanks to the Model 35. For not only is the 35 a runaway best seller (a slight misnomer because as yet, there are no real competitors on the scene), but it is also a novel experience in terms of marketing and selling.

“Consider this situation: When the marketing strategy for the 35 was conceived last year, it was decided that the main tactic would be a direct-mail program. Makes sense. But except for a small test mailing, that program has not been put into effect—because, so far it has not been needed. In fact, from the moment the super slide rule was introduced on January 4, the world has beaten a path to its door.”

Although the article doesn’t mention this fact, the marketing strategy expected that the company would sell 10,000 units in its first year. Instead, for the first time in the company’s history, it had to backorder shipments, as demand was ten times greater than expected. The magazine article goes on to say, however, that:

“What no one could possibly have known in advance was the degree to which the Model 35 has taken on star status. To the realist it may be just a super electronic slide rule; but to others it is a technological status symbol, an instrument with soul, a science-fiction dream come true. In addition, there are evidently far more teachers and students—not to mention business and professional people of all kinds—able and very willing to pay the $395 (plus handling) than anyone had reason to expect.”

In great measure, the HP-35 and its success were a result of the company’s co-founder Bill Hewlett. He and David Packard founded the company in January 1939. From the start, since the two founders were engineering students at Stanford, HP’s products were designed to be used by engineers. Hewlett-Packard began as a partnership, then, after World War II, incorporated, and finally went public in 1957. Hewlett became CEO in 1968.

So why was the HP-35 such a runaway success? The answer is that it truly was a revolutionary product.

In 1970, HP was selling the HP9100, a desktop electronic calculator that weighed over 40 pounds. Hewlett was determined to shrink the 9100 to something that could fit in an engineer’s shirt pocket and offer the same functions as a slide rule. He commissioned a marketing study of this engineer’s dream, and was given an estimate of a total market of 50,000 units selling no more than 10,000 per year. In spite of this lackluster projection, Hewlett challenged his product design and engineering teams to build it. He told them he wanted a calculator that weighed less than 2 pounds and cost less than $500. They did it in less than a year.

We justly celebrate the personal computer pioneers, but the HP-35 was the first product that placed real computing power into the hands of the general public.

William Hewlett died in January 2001. The February 2001 edition of IT World concluded its eulogy to him by saying:

“Silicon Valley has since spawned wealthier people, with higher profiles and greater fame. Hewlett never showed much interest in being a celebrity. Throughout his life he remained, at heart, an engineer.

“An engineer in the best sense of the word.”

It began forty years ago—and that’s when it happened.

Dan Wohlbruck has over 30 years of experience with computers, with over 25 years of business and project management experience in the life and health insurance industry. He has written articles for a variety of trade magazines and websites. He is currently hard at work on a book on the history of data processing.

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