Calculator blog

Musings and comments about our common interest


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latest HP15c LE vs. HP41CL

DSC_8393_062I have been using the HP15c (did I tell you that I have one for sale?) during this last two days, after some time of being using the HP41CL. In general terms, I prefer the latter, due to a better keyboard, a more informative screen and a more comfortable viewing when on a table.

However, when you’re traveling, the HP41cl is heavy, you need to pack it in your suitcase, and you risk having it damaged.

Instead, the HP15c can be carried in your jacket pocket, and you can use it in the airplane without resorting to your suitcase. I have to fly a lot lately, and i can use it this way. Incidentally, this can be done with the HP42s too - it is just that I prefer the “landscape” orientation for using the calculator with a single hand (typical when you’re sitting in a low cost airplane seat!) Apart from that, I got used to the better screen contrast of both the HP41cl and the HP15c, and then, reading the HP42s with bad light conditions and a worsening sight is tiresome.

But next week, I am returning to the HP41CL! I will investigate modules with statistical distributions.

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New HP15c LE batch arrived

Yesterday I received the last batch of HP15c Limited Edition. The several boxes of 10 units that I have received have packing dates from 12.4.2012 to 13.4.2012 (European date convention!!). All of them have the initial firmware, i.e. 15.4.2011. This means that in this last release, you will see the same couple of quirks that have affected all units so far.




Quality of keyboard seems, if anything, to have improved over my first unit. And now, when talking about "HP15c Limited Edition", you need to know that the unit I took out of the box had a serial number over 23.000 !! You can imagine that the total production might have been 25.000 units - and that's already a significant percentage of what the original 15c was! (We've been told that over 100.000 units were sold during its original production time - probably up to 150.000 if we count all origins). While 25.000 is a small number when compared with the millions of typical smartphone products, it is already a significant number for a premium calculator.


I hope that someone sees that there are tools that are just "good enough", and don't need to be changed every couple of years for the next best thing. The HP15c is one of them, and deserves to be a part of the HP calculator line, not as a Limited Edition but on its own right.


By the way, many think that the HP42s deserves similar position - but its reissue is much more unlikely, given the development means available and the size of the assignment - unless they take the work of significant members of our community to go faster. For now, let's rejoice in our luck and enjoy the HP15c LE. We do not know if we're going to have it for a long time. I will stop sales when I have just 10 left - and that'll be enough for myself and my children.

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HP 15c LE last production run.

It was beautiful while it lasted…



Several distributors have confirmed us that the last run of HP 15c has already been distributed, and that HP does not plan to produce more.


While it has been a fantastic premium product, we have to realize that this is a niche product, and, in the grand scheme of things, completely irrelevant for HP. Any of the other products made by HP is produced in quantities 1 or 2 orders of magnitude greater than our beloved HP 15c; some of them, even three orders of magnitude!


I know that some of you saw this coming, and ordered more than one unit. There were some that ordered as many as 10 (I guess that there was some ebay reselling involved) but several ordered 5 units.


Now is the time to take a decision that may last for the rest of your life…Seriously now, while if I were HP I would keep the 15c running for as long as it sells, the production logics for this kind of product implies that it may well be the last time that this model is produced.


I guess that we did not behave well, as a community, with respect to the HP development team regarding this product. As this community has been asking repeatedly for this product, the development team set to produce it, based on an already developed body – the one of the HP 12c; but it seemed to me a labour of love, because the potential market did not deserve any development time or effort for such a small niche.


Once this product had been released, as a gift for us all, there was a lot of criticism on the grounds of supposed low quality. I have and use an American unit of the first batch, and another of the European batch, and both worked flawlessly. Of the more than 500 units sold by us, only three units have been defective. There were criticisms as well about the keyboard, but anyone with experience with the current HP line would attest that it is the best keyboard in production with the sole competition coming from the HP35s and HP17bII. And compared with the original…well, in my 1985 unit, the keys are softer and shiny, but not necessarily better.


The presentation of the product was as well ahead of any other product - either HP's or the competition's (the anniversary 12c had a smaller box and no printed full manual. The only missing item in the HP15c for a completist would have been the Advanced Functions handbook, itself a masterwork in itself.)

As for the bugs…well, there really was only a bug, which had never been a problem for me (since I did not use PSE but R/S in general in my programs).


However, I found so much bad karma on the comments that, if I were a member of the development team, I would know where to put our community demands…


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Why using a handheld calculator nowadays - part II

The Smartphone as an alternative to the calculator


If you have a smartphone, then you already have a calculator - or should I say, all calculators.  Due to my job, I use a Blackberry, and the "app ecosystem" is not as rich as that of the iPhone/Ipad. I know that there are a couple of emulators for HP12c, but what's the point of loading one in such small screen, when I have several units of the original machine? But if you have and iPhone, then there is a very wide choice for you - free and payable.

The advantages of a smartphone as a calculator are several:

▪   You can have many calculators - you are not limited to one. There are emulators for practically all the calculators we love. And these are not exclusive: you can have as many as you want in your phone. In fact, calculator apps are not specially big: take into account that most of the original calculators were fitting their logic into 4 kbytes ROMs, or 8 in the case of HP15c, or even 48 kbytes in the case of the HP85a). There are not fancy graphics or memory-consuming animations.

▪   You can have the calculator with all the options - not just 4 modules to choose. There are examples of HP41c smartphone applications, that are running an emulation of the nut processor and can load any of the hundreds of modules developed for that machine; or you can have much more memory than the original; or you can have an extended character set, or more legible number fonts.

▪   The calculator is a couple of orders of magnitude faster than any of the originals, and sometimes faster than even the new models.

▪   You can even carry the manual with you - if you are able to read a pdf in such a small display!

▪   When you hear the click of the key, then it has registered. It won’t happen what we’re seeing more and more in new calculators: tactile positive feedback, and key not registered.

▪   Sometimes we forget this one: you don't need to carry an additional machine, and you’re taking the smartphone with you anyway!

▪   You can upload programs – something your calculator most likely can’t.

However, there are as well some disadvantages:

▪   You can't calculate when you are making a phone call - a situation that, if you look at it, is happening all the time. By extension, you can’t see a contact, you can’t connect to the internet, etc., when you’re calling (unless you’re using a Bluetooth headset, a reader pointed to me ;-), but even in that case, it is cumbersome to navigate the apps while you’re talking)

▪   Usually the screen is much smaller than that of the original calculator. This makes keying in cumbersome, and a high wrong key rate.

▪   Depending on the models, the graphical interface is not fast enough to keep you “connected” to the machine, even though your programs run at breakneck pace;

▪   At a test,

▪       You are not allowed to have a switched-on phone (or a device that can handle the whole library, or access to internet, or…)

▪       You want a dependable calculation device: you don’t want it to run out of batteries during the examination! 

In a way, it is a little bit like using your Iphone as a sound meter – it works, and it works well; but if you’re a professional, you want something specific – and better, for sound measurement.

At the end, the user has the right answers for himself. Myself, I lived a couple of years without calculator when my HP17bII died – and I survived in business without.



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The DM-15cc HP15c clone arrived

As a calculator enthusiast, I could not avoid buying the new kid on the block: the smallish DM-15cc from 

At the very low price of 50 CHF, it is a luxuty one can afford. I bought two units - one to keep original and another to experiment with.

It is based on the original HP15c firmware, running on a nut processor emulation on a LPC1114 ARM processor. The unit chosen should give a decent battery life - let's see. (Not that I am unhappy in any way with the HP15c Limited Edition battery life - after 6 months of heavy use (but not running long programs) it is still using the inital battery set)

The unit is really minimal: see pictures comparing it with the original 15c and the new Limited Edition. I can imagine that it is too small for some fingers, but not for mine.


The keyboard has small domes. Of the two units that I have, on one of them all keys register when they click; on the other, some rows require higher presurre to register. The key feel is excellent, while no one would exchange his old HP for this one for the rest of your life.

The colours chosen mimic more the original than the new. The new is all black, while the original had black keys and dark brown for the surface. This clone has a lighter shade of brown than the original but it makes clear what is a key and what's not.

The keyboard will resist grease and dirt. The unit is not water-proof, though: water can come through the sides since it is not sealed. Here there is a picture of the side. Some dust can make it to the screen due to the same fact.

The calculator can be easily opened and cleaned, though. This is clearly a calculator for the Do-it-yourselver.

The version I have is the so-called version 2. There is a third version coming, that will have an aluminium back and better isolation. I will order another - probably in HP16c form. This version comes with a fiber pouch, but sometimes there is a problem with static electricity, whereas the calculator resets. I have read about it in forums and have experienced myself just once. I guess that it has something to do with the screws in the back. It seems that it will be solved with the newer back in version 3. another short term alternative is to use a different pouch or isolate the screws.


The screen has low visibility under heavy light. This picture was taken on a very sunny floor. but the calculator was switched on, showing "PI". Here below you will see the original on the exact same condition, as well as the LE:


(See the brownish tint to the keyboard surface? Guess you never noticed until you saw the Limited Edition version)


The light conditons make all the more apparent any dust on the surfaces.

The better visibility comes with the original one; second comes the LE and distant third the DM-15cc

On normal conditions, the numbers are much bigger on the DM-15cc. It has two dispay modes: one with rounded digits and another with square ones (mimicking old led displays)

Blog ideas are getting accumulated, and I owe a lot of posts about getting deep into other products. Again, I need to come back to this one. I will put in all my programs and see how it compares with the original, when it comes to real world usability. As well, I will introduce in one of my samples the other firmwares, the ones sporting more memory. 

While I started my professional life as a programmer, I am in no way expert on low level programming. I would like to be able to apply the patched firmwares to one of my HP15c LEs and have a supercalculator. I know it can be made, and eventually I will be able to do it - either myself or somebody else.

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More news on the HP15c...

The HP15c is still going strong but until further notice, there are only 105 units left. Basically 90% of the turnover of the last month belongs to this calculator model. 


In the past, there were huge libraries of programs for the HP41c, but very limited for the HP15c. I encourage you to send us files and we will re-create such library in our website


There are some new developments in the emulator area - in particular related to the HP15c. As we're testing beta versions, we will not show them yet; but here's an screenshot. It will allow to import programs written in text, so that will be the way of storing them in our database.


As a Mac user, I was disappointed that HP did not provide a copy of it in the HP15c package. I have it installed on my Parallel's Windows emulation, but I wanted to have it native as well.




There is still some work to be done on the appearance side - while so far I was not able to detect any bug (Not that I have been testing thoroughly)

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HP15c finally arrived to our warehouse

Dear customers,

The HP15c arrived to the warehouse last week and this Monday the first units were shipped to our customers. Please allow some days for the units to arrive to your homes!

I have received feedback from some Spanish and German customers that have already received their units. All of them (for the sake of clarity) have the same firmware as the previous "American" batch: 2011-4-15.




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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!


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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:


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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?

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