Calculator blog

Musings and comments about our common interest


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HP10bII+ and newest HP12c "on its way"

We have been told by Moravia that the HP10bII+ and the HP12c (of the newest version) are now on their way in a boat from the Philippines.

Compared with the previous HP12c, the newest has the same innards (as shown in the previous blog release), but the bezel looks much more "metal" than the plasticky bezel of the last version. They clearly look better.

The HP12c is many times faster than the HP12c platinum, due to its atmel processor. It is also several times more efficient in consumption than the original HP12c+ and Anniversary - the processors are different and much more evolved when it comes to energy consumption. When I have some time, I will make a comparison.

Due to the programming model, much simpler than the HP15c, it is also significantly faster in simple programs than the Atmel-based HP15c. Go figure! Now, the HP15c has a much wider range of functions, and also much more memory for registers and programs.

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A HP12c's innards

Out of curiosity, I wnted to open one of the latest units of HP12c that I have received. This is a normal unit, made during HP's tenure in the Philippines (I think the actual producer is Kinpo, but I am not sure). Let's see what we find within!

When opening it, you have to remove the 4 feet in the corner. There are 6 screws to unscrew (do you find the sixth?). Trying to open it without unscrewing all will destroy the case.


The sixth screw is below the right battery. Careful!

Once opened, both sides are united by a three cables that carry the power from the batteries. The circuit, on the other hand, is visible in the back of the keyboard. It is very concentrated around the main processor. There are a couple of copper pads that I don't know what they are for. There are also a couple of small springs that are exceedingly easy to lose (This is common to other Voyager calculators of all vintages)



The white band below is an adhesive. again, I don't know what it is for. I have removed it and found nothing to protect below it.

The 6-point connector is a POGO 6-pin connector, but it is connected as a USB interface, as well as a reset device, by shorting specific pins. The problem is that this connector is completely non-standard. There was one produced long ago for the HP15c Limited Edition, but it has a completely different connection schematic. If you have one from that time you can modify it - but it won't work as is with the new calculators.

Is there not another alternative? Yes, it is. In the circuit there are provisions to solder a true USB nano connector. Where? in the right side of the circuit. Here:


I don't know the exact part number that can be connected here. You'd need also to break the case, or have opened each time you want to change the firmware. If you look into, you'll find that there is people around still interested on Voyager firmware mods. You could eventually want to repurpose the calculator for whatever type of calculator or functions. You have, though, the wrong keyboard for it. You would need to consider creating a silicone film with the lettering of whatever you want. 


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Reprogramming a HP12c into an HP15c

There is still a lot of demand worldwide for the HP15c calculator. While the HP42 was arguably a better calculator, the sheer elegance of the HP15c beats it every time. All keys had three functions - at least, since some key labels could be understood differently if you were working with numbers or matrices (yCx and yPx), or as matrices or program labels (A to E keys). 

Si ti is no surprise that people want to get hold of an HP15c "on the cheap". the easiest way is to reprogram a current ARM-based HP12c. There was a recent discussion in on hp15c firmware for the old Hp15c LE edition issued in 2011 - and it was posted there ( I will not do it here due to copyright issues - at the end this is a business and it is better to stay safe)

To do it you need a cable to connect your computer with a JTAG connector like the one in the back of the calculator. these connectors are made of POGO pins, and are increasinglt rare:


It is the 6-pin connector in the middle. This is a recent HP12c calculator. Beware with the cable: there are two types of HP12c ARM-based. The ones prior to 2015 were based on an Atmel AT91SAM7L128 and the communication protocol is serial RS232; while after that there was a new model based on another chipset, the Atmel AT91SAM4LC2CA, and here the connection is USB !! (with the same outward connection)

I enclose here a screenshot of discussion about the pinout of the two calculators:
















You can get there more information on how to get the cable. Good luck!

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Más sobre: HP12c, hp15c
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HP12c out of stock

Apparently due to the semiconductor scarcity there are no more HP12c for the time being. We have been given end-of-year delivery dates - and we have just finished our last units!

A pity - it is the fastest and best thought out financial calculator available!


We'll inform you when these units are back in stock.

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HP12c solver for polynomial expressions

HP12 Polynomial solving.

From Valentín Albillo’s “Serendipitous Solver” article. I have not read it from a long time ago, but I got struck by it sheer originality. The HP12c is maybe the perfect financial calculator, but it is quite limited when it comes to scientific purposes. It misses trigonometric functions, integration, solver…

Does it really miss a solver? It does miss a generic solver, but it does have a solver for the NPV calculation. What the calculator does it trying to solve the NPV equation for r: getting the internal rate of return (IRR)


NPV: Net Present value
CF(i): net cashflow at  i period
r : discounting rate

but if you replace  1/(1+r) = x, you have a polynomic function in x. You can now find the zeroes of the function. You just have to enter the coefficients as period cashflowsand the constant term, and solve for interest i. Careful with the monthly/yearly equivalences! . Then you just have to find X substituting again. Be careful of the discontinuities that may happen when i crosses zero. Now, the calculation will give you a zero; you need to play with the initial values of r to find others.

This of course might be done easier with the HP15c – where you just need to enter the polynomic expression as a RPN program and then apply the generic solver. No need to do substitution. 

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HP12c is back II


Here we have a box opening of the new HP12c batch. It is made in the Philippines, not China. And it looks very good!


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Más sobre: HP12c
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HP12c is back


The HP12c has been absent in Europe, Africa and Middle East distribution since at least 3 years ago. The HP management at the time could not comprehend that someone could prefer the HP12C (the one in "gold") vs the HP12c Platinum. The latter has 4 times the program memory of the former; can do more cashflows and has a double entry mode: algebraic and RPN. It also has a backspace key, something I miss a lot in the 12c (and which cleverly was included in the more advanced HP15c). The HP12c, on the other hand, is now several times faster, has a much more elegant color scheme (without the garish bright blue and red-orange colors), and has nicer screen characters (less stretched than the Platinum's). So they decided that with a single stock item they could cover both bases.

I have seen that there are many more HP12c users than Platinum's. Many financial guys are just accustomed to the 12c and would not change it for anything else. My former boss has a quite early unit that has been with him forever. He doesn't remember when he changed batteries last time. There are many that just want his trusty tool again and again - when they lose it or it is stolen from them.

Let's take a look at them, shall we? so that you can appreciate the keyboard color schemes and the screen characters. You can see the timeless taste of the original HP12c, compared with the bright colors, made for daltonic users, with the newer HP logo, of theHP12c Platinum


By the way: we think that both deserve our new leather covers over the ones supplied nowadays: Brown for the 12c, Bordeaux or black for the Platinum

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Más sobre: HP12c
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HP12c vs HP17bII comparison? Maybe


I have received mails about my previous comparison between the HP17bii+ and the HP19bII. Some felt unfair that we compared a calculator that is 25 years old with one in current production. They say that the proper comparison is between the HP12c and the HP17bII+. For some reason, no one includes neither the HP10bii+ nor the HP20/30b, nor the HP12c Platinum. Truth be told, they are right. The new HP10bii+ is a fantastic calculator for the price, and arguably much better equipped than both of our contenders with functions - but has a cheaper feel to it - albeit less than the HP20/30b family, which is not worthy of the HP tradition.

On Monday we’ll discuss both calculators (HP12c and HP17bII), their applications and typical use in real life.

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Ownership Pride and Hewlett Packard calculators

I have been reflecting in how a calculator may be atractive to some, like me; and why this attractiveness is being reduced over the years. Talking about “owners’s pride”, I guess that it went downhill the moment HP decided to put all of their calculators in blisters. When you open an hp 41c box, or even an hp 12c original box, you were in presence of a luxury item. (And if you look at the prices then, it really was). Even though the vinyl cover of the hp 12c is a little crude, and the hp41c case color was really horrible!


(Some time ago, someone helped me realize a nice marketing trick from hp related to the 41c. Remember its case, which was longer than required by the calculator? That was to make room for the card reader. From day one, you knew that your brand new calculator was INCOMPLETE!)


HP realized the “ownership pride” issue when they released the anniversary models. They were packed in an special box, that could be used for display, but as well made the calculator much more like jewelry - worth paying the asking price. (By the way, please consider the concept of “Limited Edition” or “Anniversary” calculator: quite odd, isn’t it?)


Apparently, HP message is that 12c-related calculators will not be produced anymore. So if you are willing to get one, it is now or wait for atrocious prices in Ebay. Just see what happens with hp42s units!


It seems that hp’s current calculator management has invested a significant amount of time to create the new line, heralded by the hp 39gII, and continued by the HP Prime. They are going for the educational market, that they lost without a fight to Texas, many years ago. (Now Casio seems to be taking it over again from Texas -it is e only machine I see on desks these days. Even the cheaper HP school machines correspond to a Casio model). And HP is going for at market in a comprehensive way. They prepare calculators, data loggers, computer systems so that the professor takes control of all calculators in the class, everything working integrated. The main competitor here is not Texas anymore: is the ubiquitous iPad. 


We’ve seen that the educational market will be well covered. Now, will the financial market be catered for? For a long while, the financial market was HP’s. There were some bad calculators produced in the past - I am thinking about the original 10b, the newer 20b, and partly the 30b. For the two latter, it is not that the software was not good -it is the hardware that was lacking. Horrible screen in both cases, horrible keyboard too in the first. 


They have corrected that in the lower price point with the HP10bII+. It has a fantastic keyboard, a good screen and a nice, professional appearance. It comes with many more functions than the model it replaces, fully using two shift keys. It even has a break even analysis - something that none of the other financial calculators in HP had.


I think that now HP needs to release a “prestige” financial calculator, to replace the HP17bII+, and to succeed the HP19bII. Everywhere I find a user of the old HP19bII, they would spend a lot to get back that calculator, that helped them through their studies and that inevitably failed when the battery cover broke. There is room for HP to get that. Maybe based on the tactile screen used by the Prime?


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Calculator Gift ideas for Christmas


We’re now preparing a newsletter about possible Christmas gifts in our shop. So we start discussing our products in terms of owner’s pride, and not about “fitness for use”. And we get to different recommendations!

For example, let's take financial calculators. Probably the top financial calculator, when it comes to number, width and depth of functions, is the HP 30b. In fact, it is the only one that has the Black and Scholes formula. But would I give it as a gift to a loved one? Or to myself?

From that point of view, the best financial calculator is the HP 12c Anniversary edition. It comes in a very nice box, with leather texture, that can eventually be used to exhibit it in a museum. Please take a look at the box below. It has a better keyboard than the other “normal” HP12c (it also looks better: some keys have nicer printouts), and it comes with a full manual instead of just an starting guide. And it sports the “30th Anniversary” text in the front bezel.

Second in my view is the HP 17bII+. Its new metallic front looks much better than previous versions, and the screen is miles ahead than the calculator it replaced. In my opinion, its menu system has not been equalled yet; and with the added memory, you can fill it with formulae and cash flows until you retire. That cannot be said of the 12c. It comes in a normal blister (bad), but it also comes with a leather-like case that adds to the pride of ownership. And it is the ideal choice for your friend or relative that thinks that RPN is a television channel, since it can be used in algebraic mode.

When it comes to scientific calculators, as they say, “it depends”.

If the gift is for someone you really appreciate, he will be very happy with the HP 35s  It is programmable, it can work in RPN and algebraic, and, best of all, looks incredibly good. At the time, it was also an “anniversary” product (in this case, 35 years of the original HP35), and it really looks the part. Decent case too, but comes in blister, which is not too nice.

If the gift is for yourself, I take for granted that you appreciate yourself a lot. And that you think that you deserve the best. And the best is … the HP41CL.

You probably remember that HP41c calculator. You either had one of them, or you badly wanted to have it but could not afford at the time - this was my case. 30 years later, you can.

One problem at the time, is that buying an HP41c opened a can of worms. You always wanted more: more memory, peripherals, application modules… and once the HP15c was launched, the plain HP41c was not anymore the forefront. To remain up to the edge, you needed to add the Advantage pack. And probably you wanted a number of other modules. Even if you do it now, it will take you to a unbearable cost level.

And 30 years on, the speed of the machine can be improved. But for day to day use, many think there was no better calculator: good screen, excellent keyboard, customizable…

What if someone, using current technology, changed the innards putting a new processor, fully compatible with the original “Nut” processor, and filled with all the memory that the device could address and more, and loaded with all the modules known to mankind? What if he made it faster, say 50 times faster than the original?

Well, Monte Dalrymple did. He produces boards that can be fitted in some HP41c versions, that have all that and also the possibility of a serial connector to be linked with your PC!

The only thing that is missing from the package is the HP Time module hardware (the software - with all the time-related functions - is included in the pack). You will need to shell out 100 bucks to get one in internet - a pity. But this is just if you want to measure time - in the time of smartphones, you don’t really need it. Anyway, Monte is working on that for the future.

I have access to most of the HP calculators of now and before, and the HP41CL is the one I love the most, and the one I am reaching for when I need to make some calculations. Maybe I am seen as a vintage nerd in the office, but the HP41 has everything I need for daily business - having configured it to my taste, and with all the financial calculations (including NPV and IRR for up to 20 cash flows) running at up to 50 times the original machine speed.

When it comes to graphical calculators, you have just one that can fulfill the lust of your children - the HP Prime. Based on completely new hardware and software, with a slim form factor, a multi-touch color screen, a classy metal front and a cleverly designed cover, this is the best possible gift to a student. It will help him go through the maths courses from secondary school up to university degrees. And it is much easier to program than the RPL-based devices! Its basic-like programming language is very fast, and very clear. And it can be written in your computer, with your own keyboard, tested on the computer emulator, and then transferred to your handheld.

You can see besides a real example of the calculator. As it is slim and light, it can be taken to class in your backpack without any difficulty; it is sturdy enough to withstand a youngster lifestyle, thanks to its gorilla glass screen and sturdy plastic cover; and its keyboard is very responsive, with good feedback. He will enjoy learning maths with it!

For professors: it has also an exam mode, where you can de-activate the features you want in an specific menu. With specific hardware, it can be done centrally. And you can prepare the classes with it - and your students will be able to follow you through your explanation, at their own rhythm, while you see their screen in your computer (but that’s a feature to be introduced beginning 2014). If I had to give a gift to a maths professor, it would be the HP Prime.

It has the advantage that the firmware can be upgraded through the connectivity kit and a normal USB cable. There have been already a couple of upgrades, and there are plans to greatly improve the functionality

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