# Obscure Technology

One of my primary interests is in obscure or semi-outdated technology. This comes both from a general interest in history, as well as learning about the roots of modern scientific and technological practice. Some of the major components of Obscure Technology I am currently interested in are:

- Vintage HP Calculators
- Slide rules
- Vacuum Tubes and Tube Amps
- IBM Model M Keyboards

RPN

RPN is the input method used on most Hewlett Packard calculators up until the late 90s. The system of prefix notation was first created by Polish mathematician Jan Lukasiewicz, and modified by HP to a postfix system which was named Reverse Polish Notation in his honor. RPN is a stack oriented system which allows the entry of complex equations without parenthesis. Many people do not see the use of a system like RPN, prefering the more intuitive algebraic input of most scientific and graphing calculators (most notably those from Texas Instruments). However, RPN is a fast and powerful input system once it is mastered, allowing entry of many equations in less keystrokes than algebraic systems. Also, the stack nature of RPN (every result is left on the stack just like a new input) allows seamless chains of operations to be performed on the result of the last calculation.

At the end of the day, it is a matter of personal preference. Today, most people use algebraic calculators by default, as they are almost the entire market. The last major RPN only calculator was the HP48 series, which ended production in 1997. This calculator is probably the pinnacle of Hewlett Packard design, and is still used by many.

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2005 Analogmath.com