She celebrates her first 50 portable scientific calculators, she replaced the ruler

The world’s first portable scientific calculator, the Hewlett Packard HP 35, so called because it has 35 keys, celebrates its 50th anniversary. It was launched on February 1, 1972 and marked the end of the old, big and expensive mechanical pocket calculators. . But also the end of the slide rule among science and engineering students.

The HP-35 computer was the world’s first handheld computer, the brainchild of director Bill Hewlett who, despite a marketing study warning that there was only a small market for the device, continued the project. In the first three years of its introduction, sales of the scientific calculator exceeded 300,000 units.

The HP-35 was developed over two years with twenty engineers, at a cost of around one million dollars. Equipped with a red LED display, which limited battery life to 3 hours, it allowed to calculate up to 10 decimal digits and perform all trigonometric and logarithmic functions simply by typing. Its operation was based on Reverse Polish Notation (Rpn), a data entry system based on memory registers and faster than the algebraic system, i.e. the classical system used by all calculators.

The calculator, named by Forbes as one of the 20 all-time products that changed the world, was the first used aboard spacecraft to calculate the exact angle of re-entry into Earth’s atmosphere and has achieved the summit of Mount Everest for altitude use and navigation calculations. In 2009, HP released an HP-35 emulator app for iPhone and iPad.

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