How the HP-35 Calculator Killed the Slide Rule and Made an IT Giant

by Chris Preimesberger

The new HP-35, the world’s first handheld scientific calculator, virtually made the engineering slide rule obsolete. It was HP’s first product to contain both integrated circuits and LEDs. Both technologies had been developed in HP Labs.

Combination digital wristwatch, calculator and personal calendar. Performed more than three-dozen functions to manipulate and interrelate time, calendar and numeric data. It demonstrated HP’s excellence at miniaturization.

HP’s longest and best-selling calculator. The HP-12C sold today acts and looks just as it did when first introduced in 1981, with the exception of improved performance due to modern components. Valued for its reliability, proven accuracy and long battery life, the HP-12C has become an industry standard in the business and finance community.

First calculator with HP Solve. HP Solve is an HP calculator differentiator that lets users solve an equation for any variable without rewriting the equation. The HP-18C was also the first calculator with infrared printing and with menu-driven soft keys for better usability.

First handheld calculator with two-way infrared communication.

Largely leveraging HP’s calculator technology, the HP 95LX had as much computing power as a desktop PC and was able to run many standard DOS programs. It had a financial calculator, telephone number/address program, simple text editor and infrared link for transferring data. Widely considered HP’s first PDA (personal digital assistant), it was the first palmtop PC with built-in Lotus 1-2-3.

Was a sophisticated scientific-graphics calculator featuring 3-D plotting and other advanced built-in features not previously found in calculators.

This scientific algebraic calculator had an an interchangeable keypad overlay so users could change the calculator’s color.

An enhanced version of the HP 12c financial calculator, the HP 12c Platinum boasts increased memory to allow for more keystroke programming steps and offers more built-in functions, including the option of standard algebraic mode, as well as Reverse Polish Notation mode.

This was the first handheld calculator to offer expansion via Secure Digital cards.