Which calculators run RPL under the hood?

[Giuseppe Donnini]

Hi Christoph,

Since you are one of the most knowledgeable persons in the field under discussion, and since over time I learnt a lot from reading your contributions, I feel compelled to reply to your comments.

I think that you greatly overestimate the scope of my article. All I set out to do was to answer a simple question: "Which calculators run RPL under the hood?".

In order to do so, I first set up a framework within which I felt at home, namely the calculators from the first RPL machine to the HP-49G (excluded). As this imposed limit coincides with the demise of the Corvallis division of lasting fame, it can hardly be seen as an arbitrary choice on my part, and since I'm simply not interested in later calculators, I explicitly stated that "others, who are much better qualified than myself ... may add information about the ACO calculators as well as the more recent machines". I don't use any of the calculators you mention (HP-49G, HP-39G, HP-40G), how could I comment on them?

Within the given framework, I then tried to provide as thorough an answer as possible, and I let the reader participate in the conclusions I draw by exposing all the intermediate links in my chain of thought. But as soon as there was enough evidence to determine whether a particular machine was RPL-based or not, I considered my job done, and moved on.

I was by no means trying to write a compendium on the genesis and evolution of RPL, nor on its relation to the Saturn CPU. And while the HP-71B plays indeed a key role in the development of RPL, it is itself not an RPL machine, nor does it help in identifying the RPL kernel in later calculators.

You will notice that in my charts I refrained from providing any information on ROM and RAM sizes, on LCD types, on the number of display lines, and so on, precisely because it would have forced me to discuss the different ICs. This was a conscious choice to keep the discussion focussed, otherwise the size of my answer would easily have doubled or tripled.

Much could also be said about the differences between RPL implementations, but that too would go way beyond the scope of the present discussion.