Hello happy few,

After reading – very lately, I confess - the excellent French book « Programmer HP-41 » published in the 80’s, I decided to redraw the « Logigraphe » of page 41, very confused to everyone, even to French people (yes, it’s possible).

The « Logigraphe » is the graph of all permutations available in the RPN (4 elements) stack, a very useful tool to anyone who wants to program a calc from HP-65 to 16c model. You can view and read the original document here:

Link to Programmer HP-41's PDF version

Using this strange map is simple : focus on the beginning of the graph, search for the aimed combination, and find the shortest path using Rd, x<->y, etc.

Nevertheless in these ancient times without OpenOffice, drawing a good graph was not easy, and this document appears 30 years later a bit old-fashioned. By thanking the two writers P. Descamps & J.-J. Dhénin for this wonderful book and their precious work, I chose to publish this new graph (a flattened truncated octahedron) which will be perhaps useful to some people, at least in this museum.

Here it is :

HP RPN stack permutations graph PDF version

For any OpenOffice version, please mail me.

Many thanks to Luiz C. Vieira for his HP fonts.

Xavier

Post Scriptum : I didn’t read every documentation about it (!), and perhaps this graph is a very old idea published already in some country… In this case, I do apologize for this wasted time of reading.

If not, maybe that a further step in this direction (in my humble opinion) would be an HP-41 program to inform the shortest path for any permutation combining the 4-elements stack plus the L register : the 120 permutations are by far too many for a simple 2D-graph.