In a world where smartphones are ubiquitous, it’s worth marveling that only 54 years ago, market research indicated there would be little interest in a pocket-sized scientific calculator. However, in a stroke of bad luck for the slide rule, HP co-founder Bill Hewlett disagreed with that conclusion and persevered with development of the HP-35. Let’s get into this week’s Tech Time Warp.
A revolutionary device that defied market predictions
HP introduced the world’s first scientific handheld calculator on Jan. 4, 1972. The HP-35 got its name from its 35 keys and had a retail price of $395 (or approximately $3,115 in today’s dollars).
The research indicated HP might sell 50,000 pocket-sized calculators; within months, there was a waiting list for the product. This was despite an accelerated production timeline (two years versus the typical three- to five-year cycle).
Design breakthroughs and the birth of RPN
Hewlett famously dropped the HP-35 at its press debut, and the device was unscathed. This led salespeople to drop the calculator in demos. Ultimately it became a requirement that each corner of the HP-35 and all future handheld HPs be able to withstand a 3-foot fall onto concrete. The HP-35 was designed with carefully sculpted sides to make it appear thinner than it was. The “electronic slide rule” weighed only 9 ounces, and all of its screws were hidden.
Unlike previous electronic calculators, which were known as “four-bangers” because they only performed addition, subtraction, multiplication and division, the HP-35 handled transcendental equations. It was also the first to use RPN, or Reverse Polish Notation. In the 1920s, Polish mathematician Jan Lukasiewicz had developed prefix notation to express mathematical equations without parentheses. HP recognized that adapting prefix notation into postfix notation would suit a calculator keyboard well and named the resulting logic RPN in Lukasiewicz’s honor.
The HP-35 was discontinued in 1975 following introduction of newer models. More than 300,000 units were sold.
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Photo: Marcio Eugenio / Shutterstock
This post originally appeared on Smarter MSP.