Need Advice: What models are non-programable but RPN?


Hi All -

I need to take a professional exam this fall. The test requires a calculator but it has to be non-programable.

I'm a devoute fan to my hp 48s and thus I can only use an RPN calculator.

Does anyone know of a RPN calculator (new or used) that has no programing features, but has scientific functions (10^x, e^x, LOG, LN, SQRT(x) etc.)

If so can you please let me know either by posting here or e-mailing me at

Thanks for your advice and recomendation:



The non-programmable, scientific RPN calculators I know best are all really old ones:

HP-21, 27, 32E, 33E, 35, 45, 46, 91.

There's got to be more (in the more recent models), but, for the most part, modern HP calculators have been programmable.

All calculators listed above use rechargeable batteries and red LED displays, and were made between 20 and 30 years ago. Venerable stuff, really.




The HP31, not listed, is also RPN, old LED-display model, and nonprogrammable.

I believe you are right, Ernie, and I do not know about any new RPN (LCD) HP that is not programmable. Even the financial nonprogrammable RPN ones (HP22, HP37) are old models. The still available HP12C and its predecessor, the HP38E/C, are RPN financial AND programmable.

One question: the HP19BII (I am not acquainted to this model) is both RPN and Algebraic. Is it PROGRAMMABLE or accpets math expressions as formulas stored in variables?


Luiz wrote:

One question: the HP19BII (I am not acquainted to this model) is both RPN and Algebraic. Is it PROGRAMMABLE or accpets math expressions as formulas stored in variables?


Yes, the 19BII IS programmable, just like the 17BII (and is actually a little easier to program since all the alphanumeric characters are on keys, rather than the alpha-menu approach that the 17BII uses).

I believe that the 19BII would be an excellent choice for an exam that disallows the super-powerful 48/49-type calculators, as it has the basic math/scientific functions built-in and could be programmed to provide a substantial amount of computing power! Also, since the 19BII is a "business/financial" calculator, engineering exams may just overlook its alphanumeric and programming capabilities. Then again, they may not... ;-) Obviously, I would check rather than make any assumptions!



Hey, Luiz, you left out the granddaddy of all them financial calcs: the HP-80 and its printing companion, the noisy HP-81. A cousin of mine had an 80 some 25 years ago; the only HP calculator I've ever seen with the ENTER key labeled "SAVE".





I feel bad turning the thread in to another, but the subject is teasing, amazingly teasing.

You know what? I really did not remember. Here, in Brazil, Hewlett-Packard calculators became a fever in the mid 70's and the hole 80's. In the 90's I was out of the university and saw not that much. But I got contact with them only on 1984 (maybe 1985, I'm not sure), when I bought an HP41C.

I used to chase info about HP calculators, and I still have an issue of International Electronics announcing both HP41C and 41CV. I scanned it and sent them to Dave.

But the oldies were not part of my professional development. And I feel sad for it. When I read about the 9100, a calculator with no IC's (and it just here, in the Museum, that I got this information), I felt how far I was from calculator's history and technology.

I think of them, the oldies, as the best starting point. We would never have what we have today (HP calculators) if it is not because of them. Daring, innovative look, advanced technology, the user in mind... among many characteristics.

Simply amazing.

I miss a time I was not even known about...

Thanks, Ernie.



Here's another example of the impact of HP calculators: around 1984 or 85, when there were a lot of magazine articles celebrating the 10th anniversary of the personal computer, I read an article by (or about) the guy who started MITS with the Altair computer. He said he was inspired by an HP9100 that he used when he was in the Air Force.

When I was in high school, around 1972 or 73, I had a chance to use an HP desktop programmable for a few weeks. We had one semester of computer science which consisted of learning Basic using a teletype that was connected to a remote HP computer. We also spent a little time learning Fortran using a Basic language Fortran interpreter program. For a few weeks we had the use of the desktop machine with a plotter attached. As I recall, I was the only person interested in it. I remember writing graphing programs on it, I remember that it was necessary to send the plotter coordinate pairs of numbers but I don't remember any command codes like HPGL has - basically, the only command it had was "plot absolute". Also it didn't program in Basic but in some kind of keystroke language. It was the first calculator I ever used. Some years later (mid 80's) I found a 9100B in a surplus store and bought it because (1)I can't resist interesting electronic equipment AND (2)I thought it was the model I had used in high school. I've wracked my brain and I can't remember whether that machine had the green CRT or red LEDs. I just looked at the Museum articles on the early desktop models, and it is possible that it was a 9805 without the LED display!

Anyway, my 9100 came with some documentation relating to the project it had been used for by the military, a terrestrial-based location system. There is a brief scene in "The Andromeda Strain" where they are using some exotic equipment to track down something or someone, for a moment there is the image of what must be a 9100, with its three rows of green numbers. Based on this flimsy evidence, I like to imagine my 9100 is the one the Altair guy used, and that he gave the filmmakers some shots of the machine to use in the movie.


>around 1984 or 85, when there were a lot of magazine
>articles celebrating the 10th anniversary of the personal

Didn’t Gwen Bell’s group (the then Boston Computer Museum)determine that the first personal (electronic) computer was the Kenbak-1? I think the Honeywell Home Computer (N-M catalog) was even earlier, but since it cost so much Gwen would probably have included her husband’s PDP-8’s as well [imho].

HP content: Did HP name their HP 41 calculator/computer language, “FOCAL,” after the PDP-8 language? Was it really the winning name of a contest?


I think the tenth anniversary of the Altair is what was being celebrated at that time. As I understand it, the Altair was the first computer you could buy all put together for about $400, made possible by the Intel 8080 microprocessor and NMOS static RAMs. You couldn't do anything but key in machine code by hand for a couple of years, I believe. Bill Gates and Paul Allen moved to Albuquerque and started Microsoft there to port Bill's Basic interpreter to the Altair. I'm not sure but I think the Altair included the first implementation of the S-100 bus (it might have been the Imsai). Maybe what they were celebrating in 1984 or 1985 was the tenth anniversary of the personal microcomputer, or just the microcomputer.

In my recent researches into the Olivetti Programma 101, I learned that its designer recently wrote a book arguing that it was the first personal computer. It came out in 1965, the same year as the PDP-8. Gordon Bell, in "Computer Structures: Readings and Examples", includes the Programma 101 as the limit of what can be called a stored program computer. (The next chapter is about the HP9100.)

I'd like to read about the Boston Computer Museum and the Kenbak-1 and the Honeywell Home Computer. Can you point me to any sources of information?


I used FOCAL in a PDP-11 in 1978, I remember its fractional line numbers...

I was dissapointed about the FOCAL naming on the HP41, because I feel it deserves something more original. I submitted EUREKA as a candidate for the contest, since it was an acronym for the disctintive HP41 features:

E: Expandability (hardware accessories and peripherals)

U: User-definable keyboard

R: RPN (Should I say more?)

E: Extensibility (programs can be called from other programs just as built-in functions)

K: Keystroke operation (compared to the BASIC calculators of the time, in which you needed to type "S I N ( 45 ) =" )

A: Alpha features, unusual at the time


I never knew the HP41C language was called FOCAL, I thought it was just RPN. When did they name it that? (after the machine shipped, I gather) Why didn't the name catch on?


At the time the HP41 was introduced, HP operated the Users Program Library and published a quarterly newsletter called Key Notes for the Library subscribers. In a Key Notes issue, HP asked for submissions for a contest to give a name to the HP41 programming language. Perhaps it had to do with the idea of presenting the HP41 as a pocket computer, compared to Sharp and Radio Shack models based on the BASIC language.

RPN was used since the HP35 (or 9100?) just as the stack and postfix notation operating model, and did not mean any programmability in particular.

Apart from submitting EUREKA, I never knew anything more about the contest. Only in the last years somebody at this Forum mentioned that HP started calling it FOCAL, something to do with FortyOne C... A... Language. In my humble opinion, it is not a neat name, and also it was previously used for a language which ran in Digital Equipment Corporation machines (PDP-11, etc.). In fact, FOCAL was sort of a primitive BASIC, without subroutines; but easier than FORTRAN to learn. It has the disctintive feature of "fractional" program line numbers, so if you needed to insert a line between lines 1 and 2, you just number that line as 1.5 !

The classic versions of BASIC suggested the user to number the lines from 10 to 10, to allow for insertions; and some had a RENUMBER command to clean things up after many editing sessions.


I have Jake Schwartz's CD-ROMs which have all the Key Notes on them, I will look that up. Speaking of DEC, ther are several books by Gordon Bell, who was the chief engineer at DEC for many years, which are available to be read online. One of them, "Computer Engineering", published in 1978, is just about DEC computers:

I've just scanned the index and don't see any mention of FOCAL. This is a hardware book but it does mention other languages. Is FOCAL a product of DEC or a third party?


I used DEC FOCAL in a PDP-11 (actually, it was the LSI-11 kit from Heathkit) around September, 1978. I was 20 years old and in the third year of my six-year degree in EE. As far as I can remember, it was a DEC product. Such LSI-11 (32 KBytes RAM)was one of the first computers we had in the university computer lab; before that year we used to go to an external computer center (IBM 360/370) to run our programs (mostly FORTRAN IV).

FOCAL came in a punched paper tape, which loads after loading an Octal Debugging Tool (ODT) and a Relocatable Loader (RLDR). So it took three paper tapes and about 15 minutes to boot the system before running any program. No wonder why the students (me included) preferred to program our handheld wonders! BASIC needed some 5 more minutes to boot, instead.

After those long boot delays, it was usual to have the computer hang up without evident reason. The delays were so frustrating that one student decided to investigate the cause of the problem. It had to do with different AC mains frequency. The LSI-11 derived a timing pulse from the AC supply, and the circuit caused a NMI (Non-Maskable Interrupt) to signal an impending power fail when the frequency decreases below a certain threshold. As the AC power in Argentina is 50 Hz, but the kit was calibrated for USA (60 Hz), our 20 milliseconds were too long a time for a circuit designed for 16.66 msec. That was the cause of the frequent NMI and subsequent hangups. It was very easy to solve... after knowing what was going on!


Try the following web site (my old university):

This is only any real use if the place where you are taking the exams has the same rules.

They list all the calculators approved at Sheffield university, the main thing they look for is not programmability but if they can display stored alpha information. (It can't use external programming cards either or make noise I think)

For some unknown reason they DO approve the HP42S (perhaps this is the reason they are popular...) but this is a mistake as the HP42S is able to store alpha but I think it slipped through because the letters are not printed on the keyboard (unlike the HP32S).

The list on the site is very interesting, I have not seen such a comprehensive list of calculators of all makes on the web. Try looking for the ones that are not approved.

They list the following HP RPN's as approved:



The National Semiconductor 4510 Mathematician, National Semiconductor 4640, Novus 4510 Mathematician, and Novus 4520 Scientist are all RPN non-programmable, as well as old LED models. All have log and trig functions. Only the 4640 and 4520 have scientific notation.


Also don't forget the various commie calc from the old Soviet Union. Most were RSN (reverse Stalin notation... the Soviets invented RPN along with everything else, don't you know ;)


I suppose this is just semantics, but HP doesn’t consider using the 17Bii/27Sii (oops, I wish! :-) Solver the same as “programming.” Don’t take any chances with an exam, though. I’d make sure that your calculator is approved.


Hey, I remeber the National Semiconductor 4510 "Mathematician" in the late '70s when I was an adolescent. My main impressions were poor quality of the keys, and the stack had only three elements -- somewhat constraining.


Ken --

Just curious: What kind of professional exam are you taking?

I'm an engineer who has owned a 15C since November 1983, but has amassed a nice collection since February 2002 (34C, 41CV, 42S, 48G, 32Sii, 28C, 17Bii). After trying all of these, I got to thinking: If I were to take the Professional Engineer (PE) exam and were allowed to bring only *one* calculator (no backups), which would it be?

Ya know, probably the same ol' 15C -- easy-to-read display, built-in complex functions, matrix operations, solve, integration, and *everything* on the keyboard -- no menus or function spellings to remember.

The 15C is non-alphanumeric, and might pass muster. Check the list.


Most of the old HP calcs probably are not considered as programmable,
by modern standards - for example the HP11C is quite likely to be

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