Good time to buy an HP39GS


I have just purchased an HP39GS for 18.29 GBP, taxed and delivered. One or two Amazon fronted UK suppliers are clearing them out following the release of the HP39GII.

Edit: update, disregard this next paragraph:

This is a pretty good price given that the HP39GS can be patched to boot up as the CAS equipped HP40GS. The latter retails around the 85 GBP mark.

I understand now that this back door was left open only on earlier 39G/40G units. HP "fixed" the problem on later G+ and GS derivatives. So no CAS for me.

Still, a 39GS for under 20 quid is still a good deal.

Edited: 5 Aug 2012, 1:55 p.m. after one or more responses were posted


It is still an algebraic calculator ;)


Yes! HP-39gII isn't a complete replacement for HP-39gs.

HP-39gs is better than HP-39gII in that the former has a built-in clock and beeper that the latter doesn't have.


Hi From France,

Even if a clock is not available yet, there is some timing functionality.

I use 'Ticks' for timing my programs and it is very accurate.
Each Tick is 1/1000 of second.

So I hope that a full blowup real time clock will appear sometime soon.



Hi Patrice,

How do you do this ? I've not seen 'ticks' in the v2 User Guide...
I use my HP50 for timing 39gII programs ;) And if my 50 is very accurate, my finger are not


Like that.

EXPORT Timing;

... my code here

Timing is in hours, Change conversion to suit your needs. I use it in hours because I convert it with the °'" key.

There is a function Time(<input>) but never used it.

By the way, if you edit your program, switch off and on your calc before testing for speed, it will be 3 times quicker.


Edited: 4 Aug 2012, 8:39 a.m. after one or more responses were posted


I also could find no reference to "Ticks" in the manual or on board the calculator. I am glad it is there though.

Reserved word "Time" seems to be a synonym for "Ticks" and works in the same way.


guess manual is not up to date.


Time is there and is multi-purpose. It may eventually return the actual time value (I am not 100% certain, but we may be able to turn on a clock), but it also acts in the same way TEVEL does on the 50. Time(myprogram) will return the execution time.




Its ironic that you say that the 39GS is better than the new 39gII, since the latter is mainly aimed at the Chinese market (which reads your neck of the woods! :-)). You can have the 39gII work using Chinese menus. The 39GS cannot do that!



Well, if you look at the hardware features only it could be seen that way. It had IrDA, serial, USB, the beeper, and so on. Looses out on screen.



As this thread was created to tell people to buy an HP-39gs, I think I've to tell them some facts to second the view of the gentleman who created this thread.

I've been a 3-month user of HP-39gII.

Edited: 5 Aug 2012, 2:02 a.m.


It's a wonderful machine. The more I use it, the less I miss RPL!!! That's because I use Excel VBA and Matlab to program math projects and these two pieces of software use algebraic logic. So porting a project from Excel VBA to HP39gII is not very difficult.


Edited: 5 Aug 2012, 10:50 a.m.


Finally some light at the end of the tunnel. :-)



That's about US$ 28.61 right now according to googol. After I read your post I did a search online and I just paid US$ 23.94 price and shipping. Can't wait to get it, even if it is "algebraic"...LOL


In my first post at the start of this thread I asserted that an HP39GS can be fooled into booting up as an HP40GS, complete with CAS, making HP39GS models currently being sold at low prices even better value. Unfortunately, this is not the case. This back door existed only on the earliest 39G/40G units and was closed by HP on subsequent G+ and GS models.


>Can't wait to get it, even if it is "algebraic"

Even though it's painfully slow (because its written in native "HP Basic"), one of the best things you can do for your 39GS is to install Manfred Pfieffer's RPN Add-on program from

I installed it on my 40GS (now I can use it). Love that calculators' down-toned colo(u)r scheme (less toy-like ;-)), and of course it has the CAS.

I seem to have a thing for installing RPN apps/programs on algebraic calcs (TI's, Casio's, and HP's). It gives me hope for the 39GII. If he hasn't done it already, Tim could probably knock out a simple 4-banger app in an afternoon (since he wrote the calculator's dang user language). That'll suffice until the new 39GII-based RPN graphic calc turns up (please and thank you).



Matt, thanks for the pointer to that RPN will be the first thing I download. I have an RPN for my 89-Titanium. Haven't bothered to look for one yet for the 92 or 92+ because I don't as yet have the pc cord for them. I believe there is also one out for the Nspire but I kind of like the Nspire as it is.


Nah, I did not write it. Cyrille wrote the parser/evaluator that is in use now.

Just to be clear, most of the programming language design is based on the programming language found in Bernad's xcas, which is also internally hidden in the 39gII. We didn't really "invent" it, but rather tried to match what was in use there with some minor extensions to support the app structure in use on the calculator. Most people don't realize the nearly all graphing calculators have at least a limited CAS internally to handle things like curve areas, intersection finding and so forth.

In the first version of the calculator ROM that came out, the CAS actually handled parsing of inputs and so on (although it would never return symbolic results to the user). There were some issues with that because a symbolic CAS and numeric system really are two completely different beasts and they don't mesh well in a lot of circumstances.

There was also the chance that it would spit out a symbolic result by mistake and that would cause the calculator to get banned. An example of this would be that the original 38/39 calculators were banned in some places simply for being able to do something like POLYFORM((X+1)^2+1,X) -> X^2+2*X+2. Some places are RIDICULOUSLY sensitive about anything that even remotely resembles a symbolic result.

Later on, Cyrille wrote the excellent parser/evaluator that is in use now. It is strictly numeric and really works exactly as desired with a very, very low memory requirement to run.

The 38/39/40 really are so slow in many places because the coders who did the original 38 did a lot of the UI work in sysRPL code. Things like the list editor can be painful with lots of numbers in them.

While there still are a few areas that could use some tweaking or improvement in the 39gII, I already feel it is a much, much better unit overall compared with the previous unit.


Edited: 5 Aug 2012, 10:07 p.m.


I found that xcas file just yesterday doing a google search for something. I downloaded it and the documentation and have been playing it with it all day. Nice software. I like to load it to solve a quickie problem, I can load it and solve a problem before Mathematica or Maple or Matlab even load. I wouldn't trade my math knowledge for it, but I wish I was as good at coding as all of you guys obviously are.


Thanks Tim for the detailed explanation.. and I appreciate you giving credit where credit is due (ie. Cyrille's evaluator/parser and Bernard's xcas).

Now I need to come up some more misinformation, in hopes that you'll feel compelled to set the record straight ;-).

Keep up the good work guys!


Edited: 7 Aug 2012, 6:46 p.m.


Thanks for these informations,

All this looks very promising !


I was able to get a 40Gs for $33 from TAS, which seemed like a pretty good deal as well.

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