HP-15c: Why so popular?

[KimH]

Below is all correct!

Small package with all you want/need

A "Swiss Army Knife" in a convenient size, Robust, high reliability, low battery consumption, for about $130.

When I was in engineering school- BS/MS - (Denmark 1984) it was 90% HP (15C or 41C*) - the remaining 10% were TI (58/59) or very rarely a Casio. I know that in Business Schools it was mainly the 12C or if you were financially constrained a TI-BA

(10-26-2023 01:28 PM)Dave Britten Wrote:  I think the 15C just hits the sweet spot of size, convenience, durability, elegance, and capability for a lot of people. It was also the first really affordable option for a device that can solve, integrate, do matrices, and do complex numbers, so I'm sure there's a lot of primacy bias and nostalgia from the early adopters too. It's true that the Pioneers are considerably more powerful, the 42S in particular can do anything the 15C does but better. But the 42S screen visibility is quite frankly crap compared to the nice bold segmented display of the Voyagers. Even the 32SII, while much easier to read than the 42S, doesn't quite stack up to the Voyager LCD. So it makes a nice calculator to keep on the desk for quick problem solving (though the 11C or 12C do just as well in this regard). The Voyagers are also considerably more durable than the Pioneers (which are certainly no slouch themselves).

[Maximilian Hohmann]

Hello!

(10-27-2023 10:27 AM)KimH Wrote:  When I was in engineering school- BS/MS - (Denmark 1984) it was 90% HP (15C or 41C*) - the remaining 10% were TI (58/59) or very rarely a Casio.

This is interesting! I was studying engineering in Germany, so to say just across the border, around the same time and here it was the exact opposite. Either danish students were a lot richer then than german ones, or HP had a different pricing policy (maybe subsidising calculator purchases from educational institutions?) across different countries.

Regards
Max

[KimH]

Yes, this is interesting, I was actually aware of that.. Scandinavia were more or less the same - country to country.

There was no "student Discount". On the contrary, the cost of localization was covered in-country, across GEOs. Manuals are expensive to localize - about 100USD per formatted film-page!! Which resulted in a markup for the USD price which was MUCH higher than the actual exchange rate - I recall HP using about 10 DKK to the USD where the bank rate was more like 6 DKK/USD.... so HP was even more at a premium than for example US.

TI pretty much owned the lower end of price range (much like the US) think school years 9-12 in the K-12 range, HP almost owned the higher education from then on.

(10-27-2023 11:45 AM)Maximilian Hohmann Wrote:  Hello!

(10-27-2023 10:27 AM)KimH Wrote:  When I was in engineering school- BS/MS - (Denmark 1984) it was 90% HP (15C or 41C*) - the remaining 10% were TI (58/59) or very rarely a Casio.

This is interesting! I was studying engineering in Germany, so to say just across the border, around the same time and here it was the exact opposite. Either danish students were a lot richer then than german ones, or HP had a different pricing policy (maybe subsidising calculator purchases from educational institutions?) across different countries.

Regards
Max

[ebs]

(10-27-2023 11:45 AM)Maximilian Hohmann Wrote:  Hello!

(10-27-2023 10:27 AM)KimH Wrote:  When I was in engineering school- BS/MS - (Denmark 1984) it was 90% HP (15C or 41C*) - the remaining 10% were TI (58/59) or very rarely a Casio.

This is interesting! I was studying engineering in Germany, so to say just across the border, around the same time and here it was the exact opposite. Either danish students were a lot richer then than german ones, or HP had a different pricing policy (maybe subsidising calculator purchases from educational institutions?) across different countries.

In my case I was talking about Spain, I read that in Germany was similar so I wrongly thought was the same in all Europe.

[Peet]

I don't think the 15c in particular is particularly popular, the reason for its popularity is rather the availability of an RPN calculator with no "no-go characteristics".

The 15c was the top model from a popular entry-level range and the most contemporary example of the Voyager series for today. The 11c was probably much more popular in the 1980s and the 41c is much more important for the history of modern portable devices.

The 15c probably became "popular" because HP decided on the Limited Edition about 10 years ago and thus put the 15c in the spotlight. I suspect the reason for this choice was, on the one hand, the significantly lower cost than a replica of the HP-41 and, on the other hand, no higher costs compared to an 11c replica.

[carey]

(10-27-2023 08:38 PM)Peet Wrote:  I don't think the 15c in particular is particularly popular...

The 15c probably became "popular" because HP decided on the Limited Edition about 10 years ago and thus put the 15c in the spotlight.

Hmm...cause and effect may be reversed. HP decided on the Limited Edition in response to a groundswell of requests (I recall a popular petition at the time) for a reissue of the 15c.

[Jlouis]

Forgive me, but I had to quote myself.

(10-26-2023 04:27 PM)Jlouis Wrote:  For those who says it was not so popular, I must remember you that the HP 15C was reissued two times, since its ended production in 1989, the first time with a petition for HP with thousands signatures. If it's not popularity, you name it.

Tell me another calculator that did this.

As for the reason for its success, among others already mentioned here, the landscape form factor is very important. By the way, the popularity of the 12C is not coincidence too.

Cheers

JL

[Peet]

(10-26-2023 04:27 PM)Jlouis Wrote:  For those who says it was not so popular, I must remember you that the HP 15C was reissued two times, ... If it's not popularity, you name it.

I would call it a compromise between economics and providing an acceptable model. I stick with my assumption of economics and acceptance as the cause and doubt his popularity as a reason for his choice.
And even though I would prefer an HP-41CE as a retro model, I think choosing the 15c was the better economic decision from HP.

(10-27-2023 11:14 PM)carey Wrote:  Hmm...cause and effect may be reversed.

Some people say the 15c was a high popular calculator at his time and I doubt it. I think instead the 15c le/ce represents a group of popular calculators and his own popularity emerged from this fact.

The 15c ce represents the historical RPN line what could have been realized differently. I am sure that a more aesthetic 35s (fewer bad design decisions) or a generic model (eg. a 32SII in an Voyager design) would have this position today if HP had decided on such a retro model about 10-20 years ago.

[Roberto Volpi]

My guess is that:

as it was released in the '80s, most of current old sports, including me, were young students and this calculator back in the day was really a powerful and advanced mathematical tool (and expensive too!).

We were true tech pioneers then.

Now, 40 years later, it makes us feel young again.

[Valentin Albillo]

      
Hi, Peter Klein,

(Please assume smileys throughout except in the 15-reason list below, those are in all seriousness)

(10-26-2023 08:27 AM)Peter Klein Wrote:  Pardon me if I question Doctrine here ;-).

There's no "Doctrine" here other than "RPL is an abomination and the Prime is an unreliable über-buggy toy."

Quote:I’m curious why the 15c is so popular.

It's never been popular with the unwashed masses, only with the elite HP fans.

Quote:Don’t get me wrong, it’s a very nice machine. HP managed to cram maximum possible goodness into a limited but lovely, elegant, durable package with a beautifully readable display.

You say "Don't get me wrong" and then you go on a tirade of niceties and pleasantries. Frankly, I don't get you, right or wrong. Are you trying to pull our collective leg ?

Quote:So [...] tell us, “Why I love my 15c, despite all that’s come after it.”

It's plainly obvious you're comparing the HP-15C with more modern models which were utterly nonexistent at the time it was released, what with the "equations" and stuff. The HP-15C's enduring popularity has its roots on first impressions at the time it was released, namely 1982.

Back then, 41 years ago, there was nothing to even touch the HP-15C's capabilities unless you were prepared to spend a fortune, and even then. The only model which could be considered superior to the HP-15C was the HP-41C, so there's no use in explaining its popularity by comparing it to lesser models, be they HP's, TI's or Casio's, so I'll compare it with its contemporary HP-41C. I'll mention just 15 reasons among the many ...

1. The HP-15C was $135 when introduced. The HP-41C was $295, i.e. 2.2 times more expensive
         
2. The HP-15C had complete complex functionality: a full parallel RPN stack, all arithmetic and math functions supported complex values. The HP-41C utterly lacked complex functionality.
         
3. The HP-15C had excellent matrix support, including arithmetic, inverse, determinant, norms, system solving and many other operations, with provisions to deal with complex matrices. The HP-41C utterly lacked matrix functionality.
         
4. The HP-15C could do Solve and Integrate, even both at once i.e. solving integrals and integrating implicit functions. The HP-41C completely lacked both functionalities.
         
5. The HP-15C had all hyperbolic functions (even for complex arguments !), RNG, Gamma, Linear Regression, Permutations, Combinations, MEM, mantissa, 7 levels of subroutine nesting, etc. The HP-41C had none of those functionalities and only 6 levels of nesting.
         
6. The HP-15C's algorithms for all complex functions and functionalities were exhaustively fine-tuned by William Kahan, as were the ones for matrix operations, Solve and Integrate, because he was extremely fond of the HP-15C (enamored more like) and did his best to provide it with state-of-the-art algorithms for the best accuracy and reliability. The HP-41C lacked all of those advanced functionalities and refinements.
         
7. The HP-15C instructions occupy one (most) or 2 bytes (a few) in program memory. On the other hand, most HP-41C instructions are multi-byte (up to 15 bytes,) which means that most long HP-67 programs (224 bytes max) wouldn't fit in memory and/or wouldn't run in the HP-41C's 448-byte main RAM, so you'd need to acquire a card reader and at least one Memory Module just to be able to convert and run your long HP-67 programs, adding enormously to the already high cost.
         
8. The HP-15C had RCL Arithmetic, which saved lots of program steps and time while better preserving the stack. The HP-41C lacked this most convenient functionality.
         
9. The HP-15C had the full set of 12 conditional tests. The HP-41C annoyingly lacked two of them.
         
10. The HP-15C had both labels and line number addressing. The HP-41C lacked the latter.
          
11. The HP-15C had all functions visible and readily available on the keyboard for immediate execution. The HP-41C had only a few functions visible on the keyboard, the vast majority were inconveniently buried in slow-as-molasses catalogs (not even menus) where you could only see them (not execute them) and had to be either spelled out in full or assigned to a key, both methods requiring many keystrokes and much more time over just pressing a few keys as in the HP-15C.
          
12. The HP-15C included various self-tests. The HP-41C had none.
          
13. The HP-15C used 3 standard button cells that lasted for decades. The HP-41C used 4 expensive, hard-to-find N cells that got depleted quickly if running programs and/or using the card reader.
          
14. The HP-15C was half the height and half the weight of the HP-41C, thus being much more portable.
          
15. And last but not least (this is subjective,) the HP-15C looked much more nice and solid than the ungainly, flimsier, plasticky HP-41C.
    

So here you are, all that exclusive, awesome functionality at less than half the price of the HP-41C. Technical people of that period couldn't believe their eyes !

Quote:* My opinion may be colored by the fact that my hands are too big to comfortably “touch type” numbers on a Voyager.

Then you might consider adopting a procrustean methodology.

V.
P.S.: If you want to see for yourself why the HP-15C was so popular at the time of its release and even to this day, just have a look at some of the articles and messages I posted in this MoHPC forum.

Computing Feigenbaum constant with the HP-71B and the HP-15C
HP Thread VA160 - "A modest arithmetical challenge" solved with the HP-71B and the HP-15C
HP Article VA006 - Long Live the HP-15C !
HP Article VA007 - HP-15C Nth-degree Polynomial Fitting
HP Article VA026 - Matrix Square Root with the HP-71B and the HP-15C
HP Challenge VA125 - HP-15C Mini-Challenge Speeding it up
HP Challenge VA126 - HP-15C Mini-Challenge Impossibly Short
HP Challenge VA109 - Quiz Evaluating polynomials (HP-15C)
HP Challenge VA110 - HP-15C Arguably Useful Mini-Challenge
HP Challenge VA111 - HP-15C Arguably Useful MC Solutions Comments
HP Challenge VA106 - Matrix Reloaded (HP-15C)
HP Challenge VA107 - Matrix Convolutions (HP-15C)
HP Challenge VA108 - Matrix Trilogy (HP-15C)
HP Challenge VA104 - Little HP-15C challenge for the weekend
HP Challenge VA112 - Really really small HP-15C Mini-Challenge
HP Challenge VA113 - A little HP-15C Quiz for the Weekend
HP Challenge VA121 - HP-15C Mini-Challenge RSUM CSUM
HP Challenge VA122 - New HP-15C mini-challenge

[Jlouis]

Congratulations V, once more you nailed it (as usual).

Many people became an HP fan after using the HP 15C masterpiece.

Cheers

JL

[EdS2]

Valentin, I think it would be amusing and educational if you could demonstrate a meaningful program which needs all 7 levels of subroutine! If you can't - unlikely - perhaps we should make it a challenge...

[Maximilian Hohmann]

Hello!

Excellent post as always Valentin, but I have one major objection!

(11-03-2023 01:54 AM)Valentin Albillo Wrote:  The only model which could be considered superior to the HP-15C was the HP-41C...

No, not the only one. My Ti-59 (which came out 5 years before the HP-15C) came, with the exception of hyperbolics, with all the functions that you list for the 15C. Plus a much prettier display, more memory, permanent storage and printing capability. And the "correct" form factor for a handheld device: portrait ;-)
When the HP-15C came out in 1982, the Ti-59 and the Ti-58C were still being produced. At that time, at least here in Germany, the Ti-58C (which has a little less memory than the Ti-59 and no magnetic cards) cost considerably less than a HP-15C.

Regards
Max

[rprosperi]

@Valentin - Bravo, an excellent list of advantages of the 15C over the 41C, all in one place! None of these are news to me, but I am certain I could not have created a list that complete off the top of my head. One very minor nit is the 15C does in fact have a few non-immediate commands for Matrix and comparisons, however they were conveniently documented on the permanent label on the back.

@Max - While the TI-59 (and 58/58C) had optional ROM modules supplying many of the built-in 15C capabilities (as well as many not found in the 15C), for a fair comparison these should not be included. Matrices, Complex, Solver, etc. are key differences where modules were needed and adding the cost for some of these changes the cost advantage considerably. But, yes, these machines were indeed excellent and pushed HP more than any other model at any time IMHO.

[Maximilian Hohmann]

Hello Bob,

(11-03-2023 11:10 AM)rprosperi Wrote:  @Max - While the TI-59 (and 58/58C) had optional ROM modules supplying many of the built-in 15C capabilities (as well as many not found in the 15C), for a fair comparison these should not be included. Matrices, Complex, Solver, etc. are key differences where modules were needed and adding the cost for some of these changes the cost advantage considerably. But, yes, these machines were indeed excellent and pushed HP more than any other model at any time IMHO.

All (*) the functions included in the HP-15C were contained in the "Master Library Module ML-01" that came for free with every Ti-58/59. No extra cost involved. And you got financial calculations and a (stupid) game on top - for free. And it allowed you to copy the source code of all those functions into RAM and modify them according to your needs.

Regards
Max

(*) Maybe the Gamma function is not included in the ML-01 module. But I really don't know because my lifeline never crossed path with that function - not at school, university or at work. To be honest I really don't know what it does...

[Johnh]

As an aside, I had a TI58 that I bought in 1979. It was powerful and useful and the module idea was clever. When you engaged a module program, it activated a series of soft keys across the top to give very easy control of it. The free Master Library module had genuinely useful features including solving a function, Simpson's integration of a function, or of discreet inputs , triangles etc..here is the full list, all included in the one free module:

ML-01
Master Library Diagnostic
ML-02
Matrix Inversion, Determinants and Simultaneous Equations
ML-03
Matrix Addition and Multiplication
ML-04
Complex Arithmetic
ML-05
Complex Functions
ML-06
Complex Trigonometric Functions
ML-07
Polynomial Evaluation
ML-08
Zeros of Functions
ML-09
Simpson’s Approximation (Continuous)
ML-10
Simpson's Approximation (Discrete)
ML-11
Triangle Solution (1)
ML-12
Triangle Solution (2)
ML-13
Curve Solution
ML-14
Normal Distribution
ML-15
Random Number Generator
ML-16
Combinations, Permutations And Factorials
ML-17
Moving Averages
ML-18
Compound Interest
ML-19
Annuities
ML-20
Days Of The Week, Days Between Dates
ML-21
HI-LO Game
ML-22
Checking/Savings Account
ML-23
DMS Operations
ML-24
Unit Conversions (1)
ML-25
Unit Conversions (2)

I found it fun to write programs for. I remember writing one for tic-tac-toe (noughts and crosses) that could not be beaten.

I used this for all my university engineering and the first years of my career until 1986. In my final Structures exam at Cambridge, I used the 'Zeros of Functions' and the 'Simultaneous Equations' routines to complete my exam. I'm quite sure the professors in 1982 had no idea that a student might have access to such a useful device!

But, after 8 years, if was worn out and not reliable. It just asn't an HP!

The ti5x emulator on Android has all the features, including the Module. It's fun to remember it!

[Dave Britten]

(11-03-2023 01:54 AM)Valentin Albillo Wrote:  10. The HP-15C had both labels and line number addressing. The HP-41C lacked the latter.
      
11. The HP-15C had all functions visible and readily available on the keyboard for immediate execution. The HP-41C had only a few functions visible on the keyboard, the vast majority were inconveniently buried in slow-as-molasses catalogs (not even menus) where you could only see them (not execute them) and had to be either spelled out in full or assigned to a key, both methods requiring many keystrokes and much more time over just pressing a few keys as in the HP-15C.

I fully agree with all of your observations, but I think these two could use an asterisk.

10. Line-number addressing was slightly less necessary on the 41 due to that calculator "compiling" direct-branch instructions and storing offsets for fast relative branching on subsequent executions, i.e. it's no longer needed as a performance optimization in those cases. Of course, this does nothing for indirect branching, and doesn't allow for computed branch targets (which I'm sure I don't need to describe in detail to a fellow Sharp pocket computer fan).

11. It's true that the 15C has no on-screen menus, or commands that you have to type in by name, but don't forget that the TEST and MATRIX functions require referencing a "menu" on the back plate of the calculator. There's also the idiomatic and contextual overloading of certain functions like Cy,x, Py,x, (i), I, and USER, which is not at all discoverable without reading about it in the manual (which you should do anyway, but still, if you're on the go without the manual and forget how to use one of these "hidden" features, you're in trouble). I would say the 15C has at least 95% of its functions right on the keyboard, which is still a huge margin over the 41C despite not being exactly 100%. In any case, I do think HP did a good job of fitting quite a lot more functions into the already-full 11C keyboard.

And you kind of alluded to this in point 15, but it can't be overstated how much more durable the Voyagers are than the 41C. I can't say I've seen a lot of threads on here about how to fix broken screw posts or bad zebra stripe connections on a 15C!

[nickapos]

Awesome answer Valentin, especially for us who were not around at that time, to learn the history of these awesome machines and how they compare to each other at the time of their release.
Thank you very much
I was 4 years old when 15C was released

[Peet]

(11-04-2023 09:12 AM)nickapos Wrote:  Awesome answer Valentin, especially for us who were not around at that time, to learn the history of these awesome machines and how they compare to each other at the time of their release.
Thank you very much
I was 4 years old when 15C was released

I don't think the comparison was meant seriously. Some advantages of the 41c are listed as disadvantages through a twisted description. The list is also a bit opinion-heavy instead of factual.

Compare a 15c and 41c is a bit like comparing a rowing boat and a sailing yacht. The 15c is a pocket calculator, the 41c a portable computer system. If you want an expandable system with external data storage, a printer and a huge software library, then the 15c doesn't offer much of that.

[lvt]

(11-03-2023 12:58 PM)Johnh Wrote:  But, after 8 years, if was worn out and not reliable. It wasn't an HP!

Not bad for a TI.

I bought a TI-83 for my sister when she entered secondary school (called "lycée" in France), the calculator barely lasted those three years until she graduated.