Keystroke programming vs RPL ??


HP48G is nowadays rather inexpensive and easily affordable. On the other hand HP42S is not produced any more and is rather hard to get and even more expensive than when it was produced. As a RPN fan and a HP67 owner (HP 67 not as a collection item, but still as a working horse) I have to consider transfer to "new" technology (LCD display, continuous memory etc). Comparing programming features I noticed that HP42S is the strongest machine which is still keystorke programmable (the program is basically a series of kestrokes, as on my HP67). HP 48G/G+/GX uses RPL. I looked at some programs written in RPL, downloaded from HP 48 sw archives, but I did not understand many things there. So, there are some points for discussion:

A) Is RPL worth learning at all? Who would buy a programmable calculator, if it is too complicated to program? If things change in future (stronger keystroke programmables, easily affordable palmtops, etc.) will RPL be forgotten (die as dinosaures did)?

B) Would we rather need a RPN machine with capacity and PC communication possibilities equal to those of HP 48G/G+/GX, with keystroke programmability? I think we would.

C) Though the price of HP48G were recently significantly reduced, will it be a mistake to buy now one and then spend hours and hours learning how to start programming. After you come to the end of the manual, a new approach arrives on the market...

D) If we come to common conclusion about a/m points is there a way to transfer this information to the present HP staff and to get some things moving.

Maybe I am totally wrong, RPL is easy to learn and easy to use, it is a revolutionary approach which will last forever, with many advantages over keystroke programming, or it is not too different to keystroke programming, etc. etc.

Thanks in advance for expressing your opinion.


A program written on a 42S of around 100 bytes rewritten for a 48G would take around 950 bytes. How's that for technology. That would mean that if I had around 6000 bytes of programs in a 42S, it would take up about 57000 bytes of memory in a 48G [ which it doesn't have ]

[ the above fact was given to me by MrTed J. Kerber, of D'zign, who has written programs on a commercial basis for the HP41 ,42S, 48G and 49G for Land Surveyors.]

That's why the 42S will always be my number one and number two calculators.


I have both HP42S and HP48GX and to be honest I prefer the 42. That's not only for the size. The 42 just looks so innocent and is capable of so much. It's perfect and I cherish my 42 also because they're no longer inproduction. My battery-life is about 2.5 years



Amen! brother. Over the years I have written to "Handheld Product Support" at HP in Corvallis pleading for an improved 42s...(more memory). So far, to no avail. I've only known about this site for a few days but Dave's letter in the archive (18 Nov.99) gave me some hope. I hope they don't make it "too clever by half"...a great British expression...if they really are going to make it. Richard



Personally, I am a great fan of keystroke programming; I strongly believe that in a hand-held device, this is by far the most useful programming method. Most calculator programs are not elaborate works by master programmers, but rather, "quick-and-dirty" keystroke sequences that the user keys into program memory rather than entering it repeatedly when it's needed. Which is why I was never fond of the idea of using BASIC in a calculator, for instance.

That said, I think RPL very neatly combines the features of keystroke programming and an advanced programming language. In fact, most keystroke sequences you use can be entered directly as RPL programs! In other words, if you're used to RPN calculators, learning the basics of RPL will be no problem at all.

That is not to say that there aren't a few non-obvious things that are important, such as the use of local variables in an RPL program (so as to not clutter your user space with useless variables), or using control statements such as WHILE..REPEAT. Nor is it possible to directly copy your HP-67/41/42 programs to an RPL calculator, because of differences such as numbered registers vs. variables, labels vs. control structures, or an infinite vs. a 4-level stack. But I think that these are a lot easier to get used to than it is to learn RPN in the first place if you're an algebraic calculator user.

One of the strongest features of RPL is its ability to handle objects other than real numbers much the same way as real numbers are handled. I have an example on my Web page (see, a program that calculates the radius of curvature for an arbitrary function; one of the program arguments is an algebraic expression, which the program manipulates in a variety of ways before evaluating a numeric result. Try doing that on any of the fancy color graphic calculators kids love so much these days! I think these strengths far outweigh the disadvantages of RPL being an interpreted language (hence, slower) with garbage collection and its relatively inefficient (at least when compared to keystroke programming) memory usage.



I was given a 48GX last year, as I could see the writing on the wall for my aging 41CV&CX. I bought the AUR, printer, related calculus textbooks, etc. The damn thing is languishing in a drawer while my 41's still get used almost daily. Maybe when my kids get to high school calculus I might pull it out, but frankly Mathcad, Yorick, Mathematica, etc. do that kind of thing even better.

The 48GX is just too big, too complicated and too difficult to use for the simple jobs that make up 98% of day-to-day engineering & management tasks. For the remaining 2%, a computer does it better.

IMHO, the 41/42 were pretty close to the 'sweet spot'.


--- Les []


I have recently bought a HP28S and I'm really astonished. It gathers the best features of the 48G series (at least the ones I like the most) with a compact shape when closed :).

Despite the less efficient memory management, I think RPL is far more powerful than keystroke programming. I also own a 42S and I really love it, it's better than any scientific calculator you can find nowadays. But you're restricted to the keystroke method, thought it has a debug-mode that lets you switch the calc to fast mode, for instance. In the 28S (like in the 48G series) you can use ML and "System-RPL" to code faster and efficient routines. Even the 41C had some features (or bugs) like the synthetic programming method which you can play around with.

The 42S is a great calculator to do field-work or to carry it to job, but the 28S is more than that, it's a "tool", a toy, and of course something you can amaze your friends with. I've just typed Michiel Niemeijer & Eric Toonen's remote control in my 28S and it works fine with my Phillips TV. It's less than 400 bytes. You can't do that with a 42S. You may ask why the hell do I need my calc to work as a remote control? Well, you're right, it a foolish programm, but it shows the power of the calc (ML programming mixed with User-RPL, IR control,...)

Greetings, Xose

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