Calculator blog

Musings and comments about our common interest


Published on by

Speed tests for the HP12c


As promised, here you will have some tests on the HP12c - old and new. 

We will not compare arbitrary tests, since these are very unlikely to happen for a typical HP12c user (the image I have of a HP12c is a no-nonsense business or banker user, who will not spend his life programming mathematical converging algorithms. He will instead compute net present valuers or internal return rates, and calculate the interest required for an objective monthly payment for a loan. So we will not focus on programming loops, but long financial calculations. :

We will too compare three units: the HP12c original (3 LR44 button batteries), HP12c Platinum (current version) and theHP12c current version (ARM Atmel-based, two cell)

1st test: Amortization calculation: monthly payment during 50 years

  • Loan: 200.000€, monthly payment
  • Interest: 5% yearly.
  • 50 years, 600 payment periods.
  • Full payment (FV = 0)

Amort calculation for 400 periods: f 400 amort.


  • Initial amount: -100
  • Cashflow 1: 26 (20 times)
  • Cashflow 2: 126 (1 time)
  • (IRR should be exactly 26%) seed: 10%

Here are the results:

  HP12c Orig. HP12c Plat. HP12c ARM  
Loan 102 9,5 1,0 seconds
NPV 2,5 instant instant seconds
IRR 21 2,7 instant seconds

As you can see, the difference in speed is amazing. You can argue that these type of calculations are better handled in a computer, and therefore the comparison is worthless. However, these kind of calculations are often discussed in meetings, where you don't have your computer in front - and there you may have to perform such calculations. I'd say that it is easy to live with the Platinum delays.

The platinum has another two big advantages. One, it can do algorithmic entry, as well as RPN. Not a selling point for me, but for others is a Yes/no issue. I can get my children to appreciate TPN - they have been using graphical calculators since the start and they don't see the need for RPN.

Second: it has a backspace for errors in data entry. This is a little bit of a pain in the ass in the HP12c "gold" when entering a long number: if you get it wrong, you have to start it from scratch again. I'd say this was more of a problem with previous versions where repeated keys and missed keys were normal - not the case with this latest one where no keys are missed or repeated.

On the other hand, I much prefer the smaller numbers of the HP12c over the tall, thin digits of the HP12c - also I don't like the garish color of the f, g keys and the alternate lettering. But tastes are so subjective...

Read entire post
Published on by

The HP12c "Gold" is back !!!


We have found a stack of English language HP12c - the one with gold color, RPN only, and much faster than the platinum, with a ARM processor! (what was called at the time HP12c+) Nicer screen too.

We will offer it with and without leather case - for 89.90€ and 77.00€ respectively. (all units come with the standard fake-leather PE case anyway). Order before units disappear !!


Read entire post
More about: hp12c+
Published on by

More comments on the HP12c keyboards

If you remember our previous post, we were talking about the different keyboards in HP12c's of late. Seems that it is due to products from different factories - the big % sign coming from the Invertec factory and the small % coming from Kinpo.


Here you see the codes on the back of the unit: IN04 and KN05.


Now, all the new 12cs I am receiving belong to the "big %" type...except the new HP12c Anniversary (due in Europe from next week on!)


(By the way, the HP15c Limited Edition comes as well from the same factory, and you should expect the same quality - I can attest it!)

Read entire post
Published on by

New flashing service

Today I have received a USB to com adaptor. Since most of our computers are laptops and quite new, we did not have serial adapters. I have then proceeded to update a 12c+ with the latest available software. In this particular case, it did not increase speed (it was already 150 times faster, so I am not deceived), but it corrected a number of issues compared with the original firmware.

We have decided to offer firmware flashing as a service for our purchases of a calculator. It will have a 10 € charge. The rules:

  • Calculators elegible for firmware flashing are HP10bII+, HP20b, HP30b, HP12c (ARM version)
  • The customer supplies the firmware through email.
  • The calculator to be flashed will be a new, out-of-the-box (or plastic package!). The serial number and proof of purchase bits of the packaging will be included in the shipping to the customer. (It is the customer decision to register the calculator in HP's website). Sorry, we will not flash calculators not brand new!

One of the most exciting projects is the repurposing of the hp20b and hp30b financial calculators with ultra-slick scientific firmware. The project is called wp34s and is run by Marcus von Cube, Walter Bonin and Paul Dale (in no specific order!).

You can find it on

There have been a number of releases (build number was 800 at the time of writing), and you can check whether you like the software by running the included .exe file and testing the features. The .exe file has the advantage of having the right labels on the keys!

I have not yet tested the flasher cable and software on a HP30b but I plan to do it shortly. I will then report on the results!

Read entire post