Tales from the Next Bench: The HP-35

In our on-going series looking at classic computing devices birthed at HP , we look see not only at what they did, but also give a better sense of what was happening at the time each product came to market. (For a full explanation of why we’re calling this “Tales from the Next Bench,” read here).

023threeqtr_tcm_245_923870.jpgThis installment: The HP-35 scientific calculator (1972).

The HP-35 Scientific Calculator, so called because it had 35 keys, was introduced in 1972. It was the world's first handheld scientific calculator. In one of the most amazing displacements in the history of technology, the HP-35 Scientific Calculator electronic calculator, and others like it, quickly replaced the faithful slide rule that had been used by generations of engineers and scientists for rapid calculation and simple computation.

The HP-35 was HP's first product that contained both integrated circuits and LEDs (light-emitting diodes). Both technologies had been developed in HP Labs. Bill Hewlett, who, in 1968, had challenged HP engineers to make a desktop-size computer (the 9100A), challenged them again in 1971 to take that desktop computer and make it small enough to fit into his shirt pocket. When the tiny powerhouse reached the prototype stage, HP asked a local market research firm to do a market study. They did and determined that the HP-35 Scientific Calculator would never sell because it was too expensive. Bill said "We're going to go ahead anyway." The product was so popular that HP couldn't make them fast enough.

Bill remembered, "We figured, in the first year, if we could sell 10,000 calculators, we'd break even. We sold 100,000." By the time the HP-35 Scientific Calculator was discontinued in 1975, just three and one-half years after its introduction, more than 300,000 had been sold.

If you want to get a taste of what it was like, you can play with a virtual version of the HP-35, online.  (Just note that they get one fact wrong on this page: “HP 35 was developed in two years, at a cost of approximately one million dollars with twenty engineers.” Not quite. It was more like $10,000 in material costs.)


033threeqtr_tcm_245_925859.jpgAs a joke, a group of employees gave Bill this abacus disguised as an HP-35 electronic calculator. In 1992, on the occasion of the 20th anniversary of the HP-35, Bill donated his abacus HP-35 to the HP Archives.




What else was happening in 1972? In 1972, the Dow Jones Industrial average crossed the 1000-point mark for the first time. Nixon made an unprecedented state visit to China, meeting with Chairman Mao Zedong. And five men were arrested for breaking into the Democratic National Headquarters at the Watergate.  Nolan Bushnell and Al Alcorn delivered Pong to arcades. That same year, Atari was born.  Elsewhere in the technology world, Lexitron and Linolex developed a word processing system that included video displays and cassette-tape storage.

Additional information:

•    Read an article celebrating 35 years of calculators.

•    Read an article about the HP-35 Scientific Calculator originally published on HPNOW, an internal HP web site.
•    Read the Hewlett-Packard Journal's June 1972 article, "The 'Powerful Pocketful': an Electronic Calculator Challenges the Slide Rule." (PDF, 2.5MB)

•    Read the Hewlett-Packard Journal's June 1972 sidebar, "Reverse Polish Notation." (PDF, 180KB)
•    Read the Hewlett-Packard Journal's June 1972 article, "Algorithms and Accuracy in the HP-35 Scientific Calculator." (PDF, 584KB)

•    Read the Hewlett-Packard Journal's June 1972 article, "Packaging the Pocket Calculator." (PDF, 629KB)

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