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The RPN Calculator

The first component of the computer programming curriculum is a programmable Reverse Polish Notation (RPN) calculator similar to those sold by Hewlett-Packard in the 1970's. Because you specify your program by clicking the calculator's keys, it is impossible to create a syntax error in your statements (logic errors, yes, syntax errors, no). The entire language is immediately obvious from an inspection of the calculator's keyboard. Yet this is true programming since it involves program memory, data memory, variables, looping, conditional branches, direct and indirect addressing, subroutines, single-stepping, tracing, etc. All of these topics are introduced and fully explained thanks to 33,000 words of on-line Help documentation (a book, basically). Further, I provide a full explanation of 26 finished programs that illustrate the critical programming concepts. These are fun programs. One draws spirograph pictures while another performs a least squares curve fit to solve for the age of the universe from astronomical data collected by the Hubble telescope.

A screen capture of the integrated development environment you use to write your RPN Calculator programs is shown below:

One especially nice feature of this programmable calculator is that it is also a graphing calculator, able to produce full screen plots with arbitrary formatting. You can overlay data curves, select the plotting range, print a hard-copy, and even generate a .BMP or .GIF file that then allows you to embed the plot in a word processor document. A typical graph produced by one of the example programs is shown below:

And here are just a few of the spirographs you can construct using another of the example programs:

If you would like to see what a typical program for the RPN calculator looks like, click here.

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