RPN-45 is available here:

RPN-45 HD (iPad)

RPN-45 SD (iPhone, iPod touch)



Articles on the HP-45

Using an example, this article from 1976 shows how the HP-45 computes the cosine of an angle. In German only, unfortunately, but with the help of the pictures, formulas and tables you may get the idea.

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In 1976, some clever tinkerers added programmability to the HP-45. In German only.

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A paper written by Hewlett-Packard in 1974, praising the virtues of RPN.

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In 1976, Egbert Electronics from Orem, Utah, offered a quartz kit for the HP-45. It cost $13. Here are the installation instructions.

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Internet links

The number one URL for all things "HP calculators". At http://www.hpmuseum.org/simulate/sim45.htm there's even a Java application simulation of an HP-45 based on the real ROM microcode.
Manuals (and much more) may be purchased here: http://www.hpmuseum.org/cd/cddesc.htm

Good article about Reverse Polish Notation.

A browser-based simulation of the HP-45, written in JavaScript. Runs fine on Firefox – Safari and Google Chrome, however, report a type error, refusing execution. Not a perfect simulation, but a good example of the power of JavaScript (http://www.t-denker.de/hp45/hp45.750.js).




HP-35 in Popular Electronics (1972)
A very early review of the HP-45's predecessor.

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