Not just slightly ahead of its time.


Hi all.

As the HP-35 was the first one to be a technological milestone in its own right, which other HP calcs were way beyond the technical expectations and standards of their day?

For me, I see the 41 because of its whole system architecture, the application module expandability as well the peripheral capabilities and, in addition, both its alphanumeric LCD display and programming potential.

The 15C wins my prize because of both its complex number and matrix functionality.

and, the 42S because it combines and expands on the two. Although the expandability is lacking, the full compliment of both the 41 and 15 plus the display/stack versatility to handle real, complex, alpha as well as (although element by element) its matrix handling, certainly earn my respect as the 42S is/was miles ahead of its time.

I could go on about the RPL lineage but, for starters, the 28S with its robust RPL implementation, certainly crowned that and HP as unprecedented progress ahead of its time.

What do you think?

Edited: 13 Aug 2012, 10:41 p.m.


Perhaps the 34C, with numerical integration, solver and gamma?

Now if I could just find one (at a price my spouse can live with) for my collection.....



Good idea. Yes, in retrospect, Solve, Integrate (and especially Gamma) were not available until the 34C set the stage.

Although...what were the Alpha, Beta and Gamma keys on the Commodore SR 4190R?

Edited: 14 Aug 2012, 12:13 a.m.


Although...what were the Alpha, Beta and Gamma keys on the Commodore SR 4190R?
The SR4190R did calculate Gamma, but not through the lower case gamma character, which, as well as alpha and beta, lets you enter parameters for distribution functions. From memory, the upper case Gamma is in the top row as a second function to the factorial.

Commodore called this line of calculators 'preprogrammed', and that fits well. They are function monsters. Aside from lacking enough registers for comfortably use the SR4190R, there's a lot of stuff inside. I found the integration especially useful and implemented it on a TI-59 and recently on a 15C LE.


Please clarify. Since the Commodore calculated Gamma, how could it be that the 34C was the first calculator to have the function? Or was it that Solve & Integrate were the features never before available? Also, how was the Integrate functionality made capable since the 4190R did not have a program memory to enter a function subroutine?

Edited: 14 Aug 2012, 11:09 p.m.


(1) Your information might not be correct:

Katie has the manual

(2) Integerate works by summing trapezoids. You enter a pair of coordinates as starting point and then subsequent points along the line. Great to e.g. verify histograms in scientific papers.

Edited: 15 Aug 2012, 2:18 a.m.


Thanks for the clarifications.


Honestly, these are my choice, too: HP34C, HP41 system, HP15C, HP42S and HP28S. But I also felt the HP48 series a step ahead because they added NATIVE computer comms and -later- the upgradeable O.S., none of these available before in an HP calculator.


Luiz (Brazil)


The 41c because of its expansibility, and the 15c, not as others mentioned, because of complex number and matrix handling, but, from my POV, because of its form factor (golden ratio). Esp. the latter I have not seen in any other calculator except for the Voyager series.

After all the years the only thing I am missing in the 15c is the feature to load and store programs. Despite that, its the perfect calculator for me.


The 48SX was just incredible in 1990... After the 41 I think it was a major technological milestone

Big screen, PC connection, IR, expansion port, RPL, symbolic capacity, memory to store 'notes' for exams, directory to organize yours programs, algebraix capacity, so easy complex number and matrix manipulation( I remember my first 1/x to inverse a matrix !), matrix editor, equation writer (unusable in fact because so sllllooowwwwww) ....

And for the fun Pacman game with very fast hard scroll (i remember the fisrt time i ran this program!) , Tetris, my first chess game on a calc ....

But the 48SX was also the beginning of the end of something. It's my last calc "made in USA"...

Edited: 14 Aug 2012, 5:11 a.m.


my first chess game on a calc ....

Not my graphical chess for the 28S ????

My year spent more than a bit of time in our summer vacation before honours in computer science refining the graphics. I spent the time programming the game...

- Pauli


Where can I find that? I'd love to try it.


Where can I find that? I'd love to try it.

You can find it on this page. I really wouldn't bother though. It plays glacially slowly and quite poorly.

I remember playing through one complete game however.

Instead try the Reversi game on the same page. It plays a poor to decent game. I started a machine code implementation of this but never got it ready to publish.

If you are more adventurous, my 3D adventure. You'll have to start from a memory lost 28S and you'll end up with space for nothing else on the device.

- Pauli


Looks like it is an adventure already just to type in the program :)
I'll give it a go next time I am on holiday :)


Hi Pauli !

I think it was HPChess or MLChess.


One missed in this discussion - the HP-65. The first handheld programmable calculator. The first handheld with read /write capability due to its card reader. A magnificent advance that directly led to much of what we take for granted now.

Another breakthrough? Perhaps the much ignored HP-01 "Cricket". While not a commercial success, its ability to handle floating point numbers, linear time, hours-minutes-seconds, dates, do dynamic calculations, unmatched time accuracy, ruggedness and looks are still remarkable. Which may explain why good ones routinely sell for over US$1000.

Finally, while not part of HP at the time, the Palm Pilot revolutionized the PDA industry and was a major player for nearly 15 years. While HP absorbed and digested Palm, the latter's influence was felt in the Jornada (and Compac's) series of PDAs as well. No, these weren't calculators but were handheld, ran for long times on batteries and, with Free42 and such, filled in well in our field for many.


How about the HP-27? The first calculator to combine scientific functions, statistics, and business functions? Admittedly a jack of all trades, but it took HP until the 20b (maybe the 30b if you add programming capability as well) to package up all of these together again in one non-graphing, RPN device. The 12C -- for all its longevity -- no trig functions, so it doesn't surpass the first HP business calculator.


The HP9100. No one believed you could build a calculating machine like that and it was done without any digital ICs--only one analog IC in the card reader. The ROM was a printed circuit board made using trace dimensions beyond what could really be manufactured in the day. The machine employed core memory, not generally found in anything smaller than a minicomputer and a rope memory microcode ROM found primarily in ICBMs and the Apollo spacecraft computers.

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