Calculator blog

Musings and comments about our common interest


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Last HP12c Anniversary and HP15c Limited Edition!


It is a pity, but we have reached the bottom of our 30th Anniversary hp12c stock. There is only one left - and as far as we can see, there are not too many in stock elsewhere! If you want to have an hp12c, your only choice is to get the plain 12c, in normal blister packaging. No difference from specs point of view - same processor and speed; two cr2032 batteries instead of the three button ones of the original model. Some people insist that the Anniversary model has a slightly better keyboard; the only certain thing is that the % key label is of a different font in the “normal” hp12c, and aligned and same font on the Anniversary model.

When reaching for that last unit (which you can find here) we also found something special in our stock: a brand new, unopened, hp15c  We have put it in our shop here; it is priced accordingly. It will ship unopened, but together with a new set of batteries, since the original one have Ben in the machine for the last 4 years - and it can be guaranteed that they won’t last…


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New HP12c set

There is a new product for the HP12c fanatics: a set of 4 different versions of the long-lived, standard setting financial calculator. It consists of:

  • A used, bright keys HP12c
  • A new, current HP12c
  • A HP12c Platinum
  • The last, HP12c 30th Anniversary edition

The combined price of all is 312 €, but the collector’s set sells for 280 - a 32 € off. It also includes free shipping within the European Union - and additional estimated 25 €. All in all, close to 20% off!

It’s your opportunity to enter in the HP12c area with a full collection from scratch.

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HP12c versions

DSC_7723I have received a couple of questions about the HP 12 C variants. As you all know the HP 12 C is the longest existing product in HP range. It was one of the original Calculator in the Voyager range, and it started to sell in 1981. Hence the 30th anniversary title of the latest version.

The original versions were produced with the technology of the day. They were based on a Coconut-type processor, but running at an even lower speed than the HP 41C, that is 250,000 kHz instead of 640,000 KHz in the Hp 41c. It shared exactly the same processor as the rest of the Voyager range, the only difference between them were the ROMs that each one was using. All Voyager calculators did use a 4 kbyte ROM, except the 15c which used 8 kbytes. When you compare that with the current operating system sizes, several million times bigger, it is amazing how much Mr. Kahan and the HP engineers were able to put in so little silicon space.

The latest versions are based on an ARM processor, running an emulator of the original processor, with a much higher clock speed. This speed can be changed according to the state of the calculator: very low when waiting for a key press, extremely fast when running a program. This is used to lower energy consumption when it is not needed, and be fast when required. And it is fast! My estimate of its relative speed compared with the original, is of about 150 times. Even the newer version of the HP15c does not fare as well as the 12c, at around 100x. And all this, running on an emulator layer!!!

HP discovered that some users did not accept a very fast 12c. They expected it to take its time when solving for interest, distrusting it when the results appeared too fast.

Still, this is a calculator that all users covet - and that they try to replace whith a new one, when -and if- it dies or it is stolen.

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Types of current HP12c

Current HP12c family of calculators.

There are three models available for sale nowadays (we mean, models that can be bought off stock at many places). These are:

  • HP12c “plain”: Two batteries, ARM processor, golden bezel, extremely fast. Apparently there are two types as well, and you can tell them by the elongated “%” sign in one of the types. These are supposed to have the worst keyboard. It runs the original firmware running on an emulation layer on the ARM processor. 100 programming steps.
  • 12cHP12c Anniversary: De Luxe box, slightly smaller than that of the HP15c LE, but with a better keyboard. These can be identified by the “Anniversary Edition” in the golden bezel. Same processor and speed as above; same firmware too. Apparently there was a better perceived keyboard quality.
  • HP12c Platinum. Silver bezel, alternate keys on much brighter colors (to the point of making it seem “unprofessional”), slower 8502 Processor, completely different firmware (it is said that it is binary based, compared with the BCD (binary coded decimal) that had been the hallmark of all HP calculators until then, and for which a huge amount of scientific theory had been written).

The processor speed, while much slower than the ARM-based calks, is still 8 times faster than the original HP12c. There are some significant improvements: 400 programming steps, algebraic and RPN number entry, and backspace key. The numbers are longer than in the 12c, and some say that readability is better - I tend to think the opposite.

If you want to give a present to someone in the financial world, and if that someone is young, you’d be safe getting the 12c Platinum, since you don’t know if that person is conversant with RPN entry mode; moreover, the backspace key (although a shifted one), is of great help when keying in big numbers. This was a big failure in the original 12c, that HP corrected in the much better HP15c (but which is not a financial calc!).


HP12c_Platinum_-_4But if that person has a long experience, you can bet that he would be happy with a HP12c Anniversary, that will replace his worn out, battered original model. I have seen many of them in the field, and these 25 years old calculators have held their ground nicely - but for these user, the Anniversary is like refreshing their old workhorse.


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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

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I found it!

If you read my last week's blog, I had forgotten at the office my HP15c Limited Edition. Together with the HP17bII+, they are my everyday calculators. And, until the European shipment arrives in late January 2012, I have no chances of getting it back!

Thanks God it was there! It seems that calculators are not attractive items for burglars anymore...

On another note, I received a message from a Chinese company where it asked us about our announcement in T3 magazine (the gadget specialists). What ???

It appears that it had a link to our site in a monthly list of desirable gadgets. A low punch calling HP "the touchpad makers"... 


November: HP-12C 30th anniversary calculator

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HP-12C 30th anniversary calculator

The TouchPad makers serve up this limited edition number cruncher. a programmable, retro gem that HP claims has been an office essential for finance and business folk for years.


Next November: Joby Gorillapod hybrid

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Register Arithmetic on the 12c

On Friday I forgot my HP15c LE at work. I hope to find it back on Monday morning.

So I had to make do with an HP12c anniversary when I went out for shopping, trying to keep count of the money spend on purchases. As I had been using a program before, and I wanted to keep the data used, I did not want to use the first 4 registers.

So I entered 99 € STO 5 (first purchase) and 29,95 STO + 5 and bang! Error 4 appears on screen! I try with other register: STO+6: Error 4!!

Neither recall arithmetic was working with any register

I was desperate! was my program using too many registers? No: 17 registers left.

Was there a bug in the system? I had to wait until yeterday night to try with another original HP12c (US made 1985): it did not work either. Well: at least I dod not have a defective sample.

I had then to go to the manual and check about register arithmetic. Gosh! I found there that a) register arithmetic just work with registers up to 4; and b) there is not recall arithmetic.


While the 12c is a very stylish calculator, and is very appropriated for every day business work (the three percentage keys are very much used in any kind of analysis, and very well placed), it has several points that make prefer the HP15c for every day work (and the 17bII+ for pure, desktop business work)

  • There's no backspace key. If you entered something wrong, you are out of luck - you need to clear the whole screen.
  • Register arithmetic is not consistent: it does not have recall arithmetic, and no sto arithmetic for registers 5 and up
  • It lacks base 10 logs and exponential (you can always make do with other mathematical approach).
I hope to find my HP15c LE on monday!!

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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

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HP12c Anniversary - European shipment

Once tested the new "European" HP12c Anniversary, it shows as well the 2008-7-2 firmware date - therefore, no changes.

Serial number CNA13206QS - therefore, produced in the Kinpo factory. Excellent key quality. The pouch is again slightly thicker than the plain HP12c version, but not as thick (or nice to the touch) as the one in the HP15c Limited Edition reissue (which is the best since the eighties!). It is, anyway, excellent in all counts.


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The HP12c Anniversary is now in stock !!

We have finally received this afternoon the shipment of HP12c Anniversary in the warehouse. We will begin shipping on Monday the pending orders to our customers. All of them should have received it by the end of the week. We hope you enjoy them!



If you remember the discussion about different keyboards of ARM HP12c, the Anniversary belongs to the "good" ones.

Now we're just waiting for the HP15c Limited Edition!

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