Why dont people like the 28s as much as the 42s?


The 28s looks small enough, has more keys so less cluttered. What have I missed?



Personally I don't really like its form factor.


Battery cover prone to breaking rendering the device useless is my main objection.

Otherwise, the 28s is a wonderful device.

- Pauli



I like the form factor of the 28. Dedicated alpha keys are great. And if you don't need them, you just fold the lid backwards and have a normal calculator. Excellent idea! When closed, the calculator is well protected enough that it dosent need a pouch or case. The display is surpisingly good for an LCD (contrary to the later 48 series!).

BUT: What good is a programmable calculator that (almost) nobody can program? Having to work one's way through a 1000-page manual before being able to write the most simple program puts off 99% of all users. Me included. It was the invention and implementation of RPL that cost HP the education market. What good is an educational tool that not even the teachers can understand and use?

But we've had this RPL discussion a hundred times already...



So it only does RPL and not RPN? Isnt RPL simpler for many things?



So it only does RPL and not RPN?

In a way, it does both. RPN (reverse polish notation) is the logic implemented for keystroke calculating and RPL (reverse polish lisp) is a programming language.

Isnt RPL simpler for many things?

Well, it is simpler for complicated things. If you look at some programming examples, you will find RPL programs that solve really complicated problems using only a few lines of code. But mind you: Putting together these few lines of code may take a normal person a whole week...

For the usual simple problems (e.g. formulas that need to be recalculated for different input values) RPN keystroke programming as implemented in all HP calculators before the 28 is a very simple, quick, intuitive and efficient approach. You basically type in your formula with the first set of values in PRGM-mode and have written your program in the process. Coming from that background, RPL was a huge slap in the face for most users. Because normal users do not need to solve the 8-queens-problem or sudokus on their calculators...


Addition: If you are familiar with Star Trek, you may consider the Hp28 as the ideal calculator for Mr. Spock: A totally logical and super-intelligent person who needs to solve problems, that mere mortals can not even understand. On the other hand, Scotty, the engineer, needs to recalibrate the matter-antimatter-ratio inside his warp-engine NOW, otherwise the starship will blow up in a few seconds. Nothing else but an Hp42 (or 41 or 65 or 67) can save him and his ship (and the whole universe because thats what the Enterprise's task is). The universe contains only one Mr. Spock, but many Scotty's. Therfore, mot many people are happy with their Hp28!

Edited: 21 Aug 2011, 7:13 a.m.


One real show stopper on Mr. Spocks 28 was that it always returned 'an unknown form of energy' on any imput ;-).


I think all this RPL versus RPN thing boils down to how you grew up. My first HP was a 48, the second a 50g, and not until very recently I had a RPN calc; and I quickly learnt how to program the 48 (and I'm in no way above-than-average in intelligence). A few weeks ago I wrote a simple program to draw a bifurcation graph, pixel-by-pixel, and it took me about an hour, including debugging.
Conversely, I've never managed to "reverse-engineer" a RPN program - i.e. if I read a listing, there's no way I can understand what it's supposed to do.
And all that "stack-lift" just confuses me - I prefer the 48's way, where every time you enter a number, it goes to X and everything else lifts, so that i.e. if there's a number in X, I can press "2 +" or "2 ENTER +" and the result is the same... And I *love* the "infinite stack", I think it's way more powerful than just having 'n' hard-coded levels.
So I for one find RPL very straightforward, and RPN a little awkward - though I'm getting used to it with the 34s - but as I said, I think it's down to what we learned first...



I think all this RPL versus RPN thing boils down to how you grew up.

It boils down to what is needed, imo. I rarely program my calculator, but when I have to, I take my 32SII and just do it. Since RPL is more complex and not consistent about pre-/postfix, the right syntax is hard to remember for me.

But you're right, too. When I'm used to directly edit the x-register on input numbers, RPL appears to be strange. There's a logic behind how stack lifting works on RPL machines (and the 20b/30b), that's for sure, but it's very different from RPN and produces unexpected results when used to RPN. Vice versa, RPN stack lifting must appear strange to the RPL user.

To each his own.

All that said, I like using my 48G for its advanced functions :-).

Edited: 21 Aug 2011, 2:16 p.m.


I don't understand this oposition against RPL. It is an extension without which the use of the features of the HP28 and the later calculators would not be possible. Just think about directories, names for variables and programs and the larger screen.

If you want to stay with RPN, even this is possbile. The handbook to the HP28s even has a chapter for users of older - meaning RPN - calculators. If you read this, you will find explanations why some of the features of RPN are different in RPL. RPL is a consquent development from RPN.

About the complicated programming: You only have to start the input of the program with << and then you can simply type in your keys as you would have done it on the older calcs. If you are done, you have the program as on object on the stack, which you can simply store. If you have to debug a program on the older calculators, the first step would be to write it down on paper to get an overview. On a RPL calculator you can show it on the display.

So if you want RPN only, you are restricting yourself. But HP has done both: you could buy the RPL calculators (HP28, HP48) and RPN calcuators (HP32S etc) at the same time. Both user groups were satified.


Edited: 22 Aug 2011, 4:25 p.m. after one or more responses were posted


Thomas, reread your post for some N vs L confusion!


Glad to know it wasn't just me.


Thanks for the hint. It was not easy to coordinate all the N and L's.


Seems it still is ;-)


Damn. Better now?


Better? Yes! Found 50% IMHO ;-)


Why do others find each mistake, but one self doesn't see it? ;-)


Too heavy IMHO. The 42S has just the right size, avoids extra moving parts, may still be carried in a shirt pocket, and features a clean keyboard as well. I don't want any bigger calcs. And I avoid RPL for the reasons Max explained already. OTOH, the 28S LCD is a good one.



I prefer the 28S, but maybe that's because of nostalgic value - it was the 28C/S (got both) that got me through my EE studies. At the time I was very proficient in programming the 28S, but I agree that the learning curve is steep, and I admit I no longer know how to program it.
I later got myself a 42S, mostly out of curiosity, but we never got friends.


So at the end of 3rd year EE, I bought a (recently discontinued) HP-15C and my friend bought an HP-28S. For 4th year, we used them extensively.

key layout: On the HP-15C (similar to HP-42S) all the trig and log functions were right there - on the 28 you had to shift->key to get the TRIG or LOG menu first, then press the menu key to get the function.

programming: programming on the fly was easy on the 15c as you basically pressed the same keys in the same order that you would if manually calculating it. Not so on the hp-28s - the difference is like using macros versus visual basic in Excel.

However, I did program my friend's 28S to play "home, home on the range" - can't do that with a 42s


However, I did program my friend's 28S to play "home, home on the range" - can't do that with a 42s

I programmed mine 28S to play chess :-)

And a 3D maze adventure....

Talk about a waste of my honours year.

- Pauli


Talk about a waste of my honours year.

yes, another reasons why the HP-42s is better :-)


The waste being I didn't do more calculator programming :-)

- Pauli


I remember years ago, after a long, arduous and stressful technical project where I used my HP-42s extensively, I told myself when I got done with the project I'd buy myself a present and get the 28s.

After the project, they moved me to a management position on another project. I never bought the 28s and never learned RPL. But I did get good with PowerPoint!

I miss those days, when the HP calculator was my bridge between back-of-the-envelope engineering and mainframe batch execution.


key layout: On the HP-15C (similar to HP-42S) all the trig and log functions were right there - on the 28 you had to shift->key to get the TRIG or LOG menu first, then press the menu key to get the function.

This is another calculator that looks fascinating?




This is another calculator that looks fascinating?

It IS fascinating indeed! But the 71 is not really a pocket calculator, rather a minicomputer that fits in a (large) pocket if necessary. The BASIC language is very powerful and quite easy to master for stupid engineers like me. But for simple pocket-calculator tasks it is not the ideal machine.

If you want to know whats possible with a 71b, search for Valentin Albillos challenges on this forum in the last five years or so. You will be surprised.



I definitely agree. The 71 is a powerful hand-held computer that is not very practical as a calculator. I have used mine a lot; but when I want a calculator, I reach for my 41. (I have used my 41 also for controlling and taking data from many pieces of lab instrumentation at once too though.) It is unfortunate that HP mismanaged the sales of the 71 so badly. What an absolute disgrace that was!

Edited: 21 Aug 2011, 3:49 p.m.


I saw a lot of my engineering classmates fumbling around with the 28s trying to use it during exams. At the time I was using a TI-68 which was no prize but adequate (the third shift key failed a few years after I bought it). IIRC no one really bothered to program them, they were more of a status symbol, and were quickly replaced by the superior 48 series.


The 28c/s was fairly quickly replaced by the more capable 48 RPL series with Serial Connection and/or Expansion ports. This redesign also replaced expensive "N" batteries with more common "AAA" and the fragile battery door with a sturdy replacement. The 48 screen is larger, with more memory and SySRPL capability, and numerous other advancements that made the 28c/s almost obsolete the day the 48sx came out.

In contrast,no advancement in RPN machines has been made past the 42S.


I had a 48 in first year uni but it got nicked. I replaced it with a 49+ which I still have but have never gelled with.

Im enjoying my 35s, will be interesting to compare to my memory of the 48, which was not as "fat" as the 49g+ if my memory serves me.

As a programmer, i dont think RPL will bother me. Ive read its like forth. I played with that on a Commodore Plus/4 many yeats ago :)

Edited: 21 Aug 2011, 8:17 a.m.


Actually, I love the 28S. It was the first HP calculator I ever owned and I got it during my EE studies, and programmed it extensively. I felt that menu's were the next logical step for complex calculators (e.g. I prefer the 32S to the cluttered 32SII). I also thought that RPL was the next step up from keystroke programming.
Even though I have a 50G now, I sometimes still prefer the 28S as the 50G has become incredibly complex loaded with so much more functionality. The 28S does feel incredibly slow now though ;-).


Why don't people like the 28s as much as the 42s?

Where is that stated? I knew more 28 users that 42 users in the late 80's/early 90's.

I think Allen is spot-on re: the 48 replacing the 28. I knew many more 48 users than 28 and 42 combined. Come to think of it, I knew more 15C users than 42 users.


I've known more 11c users than 15c users.



41 users are/were many more...



No argument there. My father was one of them. IMHO, the 41 was the first truly portable pocket computer. My father used the programs he created to "tune" oil refineries in the field.


the 41 was the first truly portable pocket computer.

And according to the wikipedia, only the 41C series and the HP 42s are Turing Complete.

Mightn't there be others?

post edit: I guess the
35S is too?

Edited: 21 Aug 2011, 6:19 p.m.


I suspect pretty much all of the programmable calculators are Turing complete. With the proviso of their limited memory.

Certainly those with any form of indirection could implement a Turing machine.

- Pauli


There's a very good reason that there were relatively few HP 42S purchasers during the seven years (1988 to 1995) that it was in production. All of HP's marketing emphasis was on the HP 28S (1988), followed by HP 48SX (1990), followed by HP 48GX (1993)...plus some wasted effort on that HP 38G dead end. About the only mention that the HP 42S received was in Edu-Calc catalogs.

The HP-15C (1981) had as similarly-capable competition during its production history only the HP-41C series. The HP-15C was, out of the box, much more sophisticated than the HP-41C series for many things, especially complex functions. It grossly outperformed any other Voyager as a scientific or programmable machine.

So there's no mystery at all why the excellent and still unmatched capability of the HP 42S never gained significant notice while it was in production. For every second of that period, HP purposefully hid the RPN HP 42S behind the RPL systems that HP wished to convince potential customers was what they really wanted, if only they were sufficiently sophisticated.

RPL, admittedly very powerful, is what wilted HP calculator popularity for many. A wise person on this forum many years ago distilled the issue with: "The surprising thing about RPL is not how easy it is for hard problems, but how hard it is for easy problems."

Edited: 22 Aug 2011, 12:39 p.m.


For every second of that period, HP purposefully hid the RPN HP 42S behind the RPL systems that HP wished to convince potential customers was what they really wanted, if only they were sufficiently sophisticated.

And in my eyes they were right, the 42S was only there to support those archaic users that wanted something to replace their beloved 41C_'s (which it failed miserably to do because it was crippled by lack of expandability & I/O).

(Mike - please do not take me seriously, I am just putting in a lighthearted jab in this "argument" ;-).

I graduated from high school in 1990 and went into college to be a mechanical engineer right afterwards. The details are a little fuzzy, but I remember that one of our professors told us we would need a good calculator for all of our classes. He explained that we needed something that would handle matrices and simultaneous equations among other things, but those were really important. HP must have been recommended because that is all that we students bought. Back then there was no internet so that we could check reviews or do research. I ended up at a local store and I had to order my calculator. I am fuzzy on the choices, but I remember one option being about $60 or $80 and it had limited abilities for matrix and simultaneous equations, so maybe that was a 32S, but I could be wrong. The next option was a 42S at $120, and the last option I think was a 28S at $235. The 42S would do what I needed and was about half the price of the 28S so that is what I got. I didn't understand how the 28S could be worth so much extra money, and keep in mind I had to use part of a student loan to order the 42S. It served me well for all of college and I passed the FE exam with it as well. I didn't even know much about programming and never really tried to learn. The quadratic equation program was the only thing I remember ever putting into it, but I knew that one by heart so it was pretty much pointless anyway.
Others back then splurged for the 28S, but most seemed to have a 48S or later on a 48G. I even remember one or two having the 48SX or GX. I was in so much awe of a calculator that could load programs, information, and formulas on the cards. At the time I felt like I was at a disadvantage to a certain degree with my little 42S.
Now there are so many who wish we could still get such a small little calculator.


When I was studying engineering I bought the HP 28S. Just the possibility to solve a linear equation system (3 x 3 or whatever) with complex coefficients by allocating the two matrices in the stack and clicking a key was enough to convince ALL my schoolmates to run and get one. At that time other people already had a Casio PB 1000 or even an HP 41 but they had to admit the HP 28S was far superior for everyday calculation. I don't know much about the HP 42S but I guess that the screen and RPL language offered by the HP 28S makes this one the right election. And we should not forget the possibility to have in the same enviorenment real numbers, matrices, lists, many objects. A luxury that other older calcs could not afford.


The HP-28S was my second HP calculator, purchased exactly because of the very reason you mention. Although no user program was necessary for that task, I preferred to use this one then. The HP-42S has a nice linear system solver as well. Limited I/O is their great weakness, however.

Edited: 22 Aug 2011, 8:09 a.m.


1) RPL.

2) Not easy programming for those who were familiar with the classic paradigm.

3) Little memory on the 28C.

I remember the enthusiasm and then the intense disappointment the 28C caused me when a friend lent me one for a couple of days (1987?)...


Ah, the perennial RPN vs RPL debate. :)

I learned to program on an HP-41C. I used RPN before I learned BASIC, let alone C. The HP-41 way of doing things is still the most natural for me. I had a career as a programmer and systems specialist, and cranked a lot of code over the years. After I rediscovered HP calculators in 2005, I bought some RPL machines and set out to write non-trivial programs as an exercise. My experience was that RPL was hard to learn. I'm sure that had partly to do with my RPN hard-wiring but I also think that it's manifestly true that RPL is more challenging, merely measuring that by the flexibility it offers over RPN. However that may be, I came to greatly enjoy RPL on the 48GX.

As a diehard 41C fan, I will always regret that HP took the direction it did with RPL. In the late 80s, calculators were still relevant in the broad market of computing devices. If they had chosen to build on the RPN model, it's likely that we'd have HP machines today that I could love without reservations. But that is a selfish and atavistic attitude. HP went with RPL, and that branch of the calculator tree flourished in a technical, if not a commercial sense. I rejoice to see that other RPN troglodytes, like me in tastes but with greater technical chops, have taken up the challenge of moving the RPN model forward. I'm bringing my 30B to HHC for some post-HP RPN hot-flash TLC. I hope to see some of you there.



I love the 28S - it was my first HP at university. I upgraded it to a 48G a few years later and was disappointed. Now I have a large collection of HP's, including 2x42S's and 7x28S's (some examples of mine here: 28S clear, 28S normal and 42S ) I have 28S's made in USA, Singapore and Indonesia, as well as 100th anniversary edition and clear case.

What I love about the 28S is the separate alpha keyboard, which makes programming so much easier, the easy access menus, and the overall layout. It does fold into a neat little closed case which is well protected. Downside is of course the battery door, but if you are careful then they can survive well. I agree with earlier posts that it has a lot to do with what you are used to.

For daily use, I have a 28S, 42S and 48GX on my desk. I tend to mix it around a bit (just because!!). Cheers, Keith

Edited: 23 Aug 2011, 11:59 p.m.


Great samples, especially the clear one! Congratulations!!


That photo stream is a great pleasure to browse. Thanks!


Thanks! I am slowly getting all my collection online. I've just posted a pic of my 94E & 94F together - just need a 94D to complete the picture!!

Edited: 26 Aug 2011, 1:04 a.m.

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