Calculator blog

Musings and comments about our common interest


Published on by

HP15c Warranty repairs

One of our customers made use of the warranty for the HP15c Limited Edition. He just contacted us about his experience. 

The problem he had on his calculator was a small damage on the front panel, just above the x key. I have included his picture - better one image than 1000 words. As he is a collector (as yours truly and many of our other esteemed customers), it was bad enough for him to be upset. He already had other 2 hp15c LE's, but these were intended for relatives.

He called the Spanish Calculator Support team (there are support teams for many countries - later I will post the addresses and telephone numbers somewhere in our website), and he was sent a new calculator packed in bubble wrap in just 5 days.

I would have guessed that it would take a lot of time for the HP15c to reach the support channel - we have been waiting for it for a long time ourselves.

In addition, he has been told that, if he's not contacted by HP in 10 days, he will likely be able to keep the (functionally 100% working) defective calculator.

Talk about service!!

(Additional note: I am seeing in the fori I attend a lot of badmouthing on the HP15c LE. I respectfully 100% disagree. The packaging is first rate, the key click is as good if not better than any other current HP calculator (and on par with the HP17bII), and it is competitive with the feel of the original one (softer, shorter travel distance, but can be seen as mushy sometimes). The speed...well, it makes the HP15c attractive for tasks you would not dream to run with the original model (unless you think that waiting 1 minute for a result is acceptable nowadays)

There may have been some initial quality problems, and some bugs related to the adaptation of the original firmware to a completely new hardware. However, the new model is retrofittable, which the original was not. The bugs are very minor and far apart, and I had not used the feature that causes it in all my life with the original model.

This calculator has been a labour of love of the HP calculator team. You guys asked for it - they took the smallest opportunity they had to find a way to produce it. With the kind of response they are receiving, I don't think they look forward to make another favour to the calculator lovers. If I were them, we all should be forgetting about the HP42s reissue...

Read entire post
Published on by

First appearance on print of TheCalculatorStore

I received some days ago a mail from Japan, asking me if I intended to sell there, and making strange references to a T3 ad. I have never made any ad anywhere, except from google ads; so it was strange to me. 

Some time later I flew to Lisbon, and got a complimentary copy of the latest issue of T3, in Portuguese. Here is what I found, and imagine my surprise. I guess that the HP15c LE will be of higher interest for these folks!


Read entire post
Published on by

At long, long last...The HP15c Limited Edition Arrives !!

We have been informed that finally the HP15c will be arriving to Europe on the 2nd half of January 2012. Shipment to final customers on week 4 2012.

The sales price has been set at 109,99 €.  You can find it here:

HP 15c Limited Edition

The buyer will receive a substantial box, ideal for a gift to an engineer friend (my best engineer friend is myself, by the way), or as an exhibition box in your collection. Here you see it as you will receive it, with the plastic cover:


And here without it:


Once opened, this is what you see:


And here you have the calculator, together with an original unit:


The pouch is substantially better than the one in the 12c. I prefer it to the original as well - YMMV

There is a difference with the back: is black lettering on silver metal finish. It seems to have a vernis on top - after 3 months using it, it has not lost any part of the labeling.


It can be "repurposed", as any new 12c can. Please see the connector between the 2 batteries.

Please see here a close look:


Read entire post
Published on by

HP15c clone coming back - but now with a competitive advantage!

If you remember, some time ago we reviewed a project for a clone HP15c calculator made in Switzerland. While the project was extremely interesting, it had the worst possible timing: it coincided with the reissue of the HP15c by Hewlett Packard. With good sense, the creators backed off and re-thought the project, in order to give the user something more than the original did.

I am carrying the HP15c Limited Edition every day with me, and while its size is smaller than most calculators, it is a tight fit in my shirt's pocket, and it fits well in my jacket's; but sometimes I would like it to be smaller.

Enter the HP15cc:

First a pre-production sample



Then a more developed sample:



I look forward to get one. and you?

Read entire post
Published on by

Tutorials for HP15c

It is amazing the vitality in our admittedly small and "vintage" hobby. As soon as a new edition of a vintage calculator appeared, there have been people working on it.


I plan to give some of these HP15c calculators to my children (I will buy a decent stock of them for myslelf), but it is good that there is already a programming tutorial for it. I have included links to it in my Manuals and Support page. Thanks, Eddie for it!


HP15c Programming Tutorials from Eddie´s Math and Calculator Blog

Chapter 1: The Stack

Chapter 2: Basic Programming

Chapter 3: Registers

Chapter 4: Tests

Chapter 5: Subroutines

Chapter 6: Loops

Chapter 7: Solve and Integrate

Chapter 8: The summation program

Chapter 9: Derivatives

Chapter 10: Statistics

Chapter 11: Flags

Chapter 12: Memory and indirect registers

Chapter 13: Indirect Addressing and subroutines

Chapter 14: Complex numbers

Read entire post
Published on by

No HP15c for Christmas

We have received confirmation from HP that there will not be that "early" shipment of HP15c for Europe, and that the only HP15c will arrive by the second half of January.


As I have been using a sample for the last 2 months, I can tell you it is a pity.

The other day I opened my pristine, original, 1985 hp15c and surprised myself preferring the key feel of the new one. Maybe due to ageing, the keys in the old one are "mushier", although still very precise and comfortable.

For those customers that ordered an hp12c anniversary and told me to wait until the hp15c arrives to ship them together, we offer to send to the 12c Anniversary and we will deliver the HP15c with free shipment when it arrives. Please contact us by email to

Read entire post
Published on by

HP Operating Environment limits - HP15c Limited Edition

Do you remember when old HP product manuals came with "operational limits" notices? I have seen several that stated operating maximum and minimum temperatures, as well as storage temperatures; I seem to recall that there were operating maximum altitude on some of the products as well.

These notices were inherited from the time where HP was the world's best measuring instrument producer - and you needed to know if the measure had been taken within the right operating bracket - but that's not the case anymore.

At least you can make tests for yourself. The HP15c LE works well at -5ºC (23 ºF), at 3.571 m (11.716 ft) of altitude, on Jungfraujoch Sphinx observatory:


The view from Jungfraujoch, in mid-Switzerland, is amazing - you see miles and miles of glaziers, and several 4k+ peaks. You can see as well possible falls of more than 2000 m when you stop with the train in the north face of the Eiger peak - since 1935, at least 64 climbers have died trying to climb it. No wonder I took the picture firmly grabbing the calculator!

Read entire post
Published on by

HP15c Limited Edition arrived

We received the first samples on Friday afternoon, just before leaving for the mountain cabin. I opened it and played with it, but took it with the box and my trusty HP15c from Oct. 1985, made in USA, for meaningful comparisons.

So fast I was that I took the camera but not a proper flash. Hence I took pictures leaving the cameras on the balcony floor. The strong sun washes out the colours in most pictures, so all differences get exacerbated.

First of all, let's see the box. It is substantially bigger than the HP12c anniversary. Let's see both:


And the anniversary one:


The reason being the inclusion of a "real" manual instead of a starting guide as in the rest of calculators.

The manual is equivalent to the original manual, set with modern letter types and current HP design, but for the rest is equivalent to the old one - errors included! It is as well bigger than the original.

Here it is without the protective plastic:


Please note that the strong sun makes the little dust specs appear more clear. I had already opened the box and played with it - hence the dust.


And now for a comparison between the new and the old. Be aware that my old one is nearly pristine, and I separately bought a true leather cover in dark brown colour:


While both calculators are black, the newer is blacker than the original, but the strong sun enhances the differences.

The pouch is slightly thinner than the original, but clearly thicker than current HP12c versions - included the Anniversary. Look for a comparison (the one in front is the HP15c's):


 Now, a look at the back. The new calculator needs more room for the batteries and therefore less is left for the "instructions" in the back. Let's see how it was in the original:


...and the new one, in plain metal. I have removed the battery cover so that you can see the nice Lemo connector that will allow us to update the firmware and eventually change it for a new one. (can perfection be improved upon?)  Let's see how it ages!


By the way, do I feel proud of the low serial number!

And now the naked frontal view:


Sorry for the dust! It was not that much in reality.

Now, for a comparison, the old one:


As it is too late in Europe, I will continue tomorrow with a proper review on other aspects. Before entering in detail, let me say that I am very happy with it, and that it surpasses the original on several counts - including key feel. 

More tomorrow.

Read entire post
Published on by

A couple of speed tests and some more comments on the new HP12c

We have made some speed tests with the simplest of programs:

01 +

02 GTO 01

And compared the newest 12c Anniversary (firmware 2009-07-02) with an ARM-based 12c with original firmware (dated in 2008) and another one updated with the latest firmware (2009-11-19).

For the 2-minute test, the first and second are more or less equal; the latest firmware is noticeably faster (reaching 153.268 iterations vs 141.126, 8,6% faster.


To complete the comments made in last blog, the keys in the new 30th anniversary machine are blacker than the previous one , and the lettering is much sharper - less blurred.

Of course, the original one are even blacker and the lettering sharper, but as they are more shiny it can lead to poor visibility in very bright environments. As well, the tactile feedback is different. I have used several original 12c's and some of them have developed mushy keys, soft to the touch (this happens as well to some of the original 15c I have had the opportunity to use, although not mine). This must have to do with the 25+ years of life of these devices.

During last trip I used the original one - and I still cannot decide which one to use for keyboard pleasure - softer in the old one, more responsive but also more springy in the new one. Now, when it comes to calculate a 10-year IRR, there is no comparison - although that does not happen every day.

As for overall fit and finish, the metal trim in the newer ones has a vernish protection (if it's a metal trim and not a plastic imitation) which will likely protect it better than in the original (where it was a weak point for cosmetic reasons)

And I have been told at the office that my HP15c LE sample has arrived but the post could not deliver it for some reason - for travelling reasons I will not be able to pick it until next wednesday...

And I expect to have some availability news by the end of next week


Read entire post
Published on by

Some press reactions to the HP12c, HP15c reissues

Let's begin with Engadget . They present a video of HP's Dennis Harm, and they talk about "1981 coolest calculator". They mention as well the HP15c reissue for those to which the 12c does not move. They coin the term "retrocalculation". One would have thought that it was coming from the results back to the original data!

Hypebeast compares the well-being of a 30 years old calculator with the early death of the HP tablet. It recalls as well that the original introduction price was 150 dollars - now it is 80 - negative inflation for a 100-fold speed improvement.

GearPatrol Shows as well the calculator with the same picture that appears everywhere. (It is surprising that a financial calculator is shwon with Pi in the screen. It is a feature the calculator does not have!). "Iconic dinance industry tool", they say. talks about the 30th anniversary and not the actula calculator. It was a surprise seeing a different picture from the rest of the bonch - since it is an old HP12c! You can see that it is an old model since the keys are shiny, as compared with the newer, matte-finish keys. (In the past, HP calculators had double-shot keys: both the key and the number were molded together - that is, the number was in the key plastic and could not be worn out or erased! Talk about quality and attention to detail!)

He goes on talking about his long-lasting unit from 1986. (Only 25 years old) Voyager family models were famous for their long lasting batteries - his have been changed just once since he bought it!

"With the rapid and untimely demise of the TouchPad, you might get the sense that HP isn’t very good at keeping its products alive", says ZDnet Mobile. "The interesting thing about the HP-12C is that HP never really anticipated it lasting so long. Expecting a two-year life for the device, HP was surprised to see that the HP-12C lasted much, much longer. Perhaps HP could learn a few things from the device and apply it to its tablet strategy."

Market Watch Shoes the standard HP press release

Michael Doan uses the Iphone for calculations, and confesses he was never a 12c man - he bought instead a 18c (see the site for an example), but he too likes the timeless design that lasts.

Lets include as well HP's historical video. 



Read entire post