Four types of RPN

[hansklav]

(09-03-2014 06:37 AM)walter b Wrote:  

(09-02-2014 10:52 PM)hansklav Wrote:  My proposal for a descriptive classification would be:
Each description of an RPN type includes three things:
- description of the bottom of the stack (Classical or Entry line RPN)
- presence or absence of "top copy on pop" (top-copy or top-neutral RPN)
- description of the hight of the stack (bounded n-level stack or unbounded stack)

At the moment in real life there exist only four types of RPN:
- Classical top-copy 4, 5 or 8-level stack RPN
- Classical top-neutral unbounded stack RPN
- Entry line top-copy 4-level stack RPN
- Entry line top-neutral 128-level or unbounded stack RPN

If we reshuffle this list so that all members of our community can easily remember it we get:
- Classical top-copy 4, 5 or 8-level stack RPN (the "classics", a.k.a. alpha type)
- Entry line top-neutral 128-level or unbounded stack RPN (the "graphics", a.k.a. beta type)
- Entry line top-copy 4-level stack RPN (the "??", a.k.a. gamma type)
- Classical top-neutral unbounded stack RPN (the "???", a.k.a. delta type)

Sounds better IMHO.

Just let me add that the alpha type covers not only the Classics but each and every HP RPN calculator from the HP-35 to the HP-42S. Beta covers what's known as RPL. Gamma is just represented by two calcs AFAIK (so it could turn out being a sidetrack). And I'm not aware of any tangible calc representing delta.

You are right concerning my use of the word ‘Classics’. For a moment I forgot that the term ‘Classics’ is already in use for a specific subset of the α type (alpha type) RPN calculators, notably those issued by HP in 1972 or shortly thereafter. So ‘the Classics’ is not a good term for the whole set of α type RPN calculators.

The RPL calculators are not identical to the β type (beta type) RPN calculators because the HP Prime is β type RPN in the above definition but doesn’t have RPL as a programming language. The β type RPN calculators could be covered by the term ‘HP graphing RPN calculators’, but that is a rather long one. My suggestion therefore was ‘the Graphics’, but I don’t think that’s good English…

While δ type (delta type) RPN is not available as an actual hardware calculator, it is potentially available to the desktops or laptops of more people (millions) than any of the other types, in the form of the RPN-mode of the standard Calculator (Taschenrechner, Rekenmachine, Calcolatrice, Kalkulator, Kalkylator, &c.) application in Mac OS X.

Hans