Calculator blog

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

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

I have been told that another typical problem with the Spice machines is that the battery cover breaks. At least two persons have asked me for a replacement of the original.

When you see the design, you see that there was a ongoing "theme" in HP design: the pricinples used in that battery cover were later used in the Voyager series (at a smaller size). Even the later voyager series (with the ARM processor) that had two CR2032 batteries shared the same design clues. There is a significnat difference: the spice cover has two feet glued in - so it has support function too. 

I started with HP by using a HP33c during my studies - until 1st course of engineering. The battery cover broke when the batteries grew in size after being in a drawer for several months. A pity!

Here are a couple of examples: observe the upper side. It is amazing that the Spice is so similar to both!

I created the HP Spice battery holder on request from Ignacio Sánchez. He is the person with the biggest HP calculator collection that I know. He told me that one of his problems is that he could not use his Spice collection. These were small machines produced at the end of the seventies that occupied the lower cost position in HP's calculator roster, replacing the Woodstock series. They had a nice form factor a keybaord, but they had some design issues. One of them was the battery. Once the original pack was damaged, leaked or broken, the problems would start. If you replaced it with AA-type batteries, these were a couple of milimeters longer than the original pack, putting an unwanted pressure on the terminals (that often broke) and the box (same). The consequence is that, in Ignacio's opinion, 80% of the world pospulation of HP Spices are now unusable, due to broken contacts, unavailable batteries, or broken bodies and back cover.

He gave me the idea of forgetting about AA batteries and replace them by the smaller AAA. To achieve the required length, we would use springs - the ones used in the HP 41c battery bay would do well. 

We did the design and it worked well. For Ignacio it was fantastic because he coulld use again his Spice collection, without having to resort to expensive refurbished battery packs.

What has surprised me is that this is general feeling among the customers. It is probably the product we have created that -pgives more happiness: it allows our customers to use calculators that they had not used for a very long time!

But we also have learned a couple of other things. In the original calculator, electrical contact was assured due to a small spring effect on the connectors. If this connector was broken, the spring action was lost and the calculator would not make constant connection, makiing it unusable. But in our part, spring effect is provided by our own springs located into the battery bay, so it effectively makes possuble to use Spice units with the contacts broken - no need to repair them! This was unexpected and it is a bonus for the purchaser - and in some cases saven him an expensive repair: see the comments we have received in the customer valuation for that product.

So, a product we had created just based on solving a single a technical issue is resolving more problems than originally expected; and apparently is opening a door that was closed before, enabling the use of some calculators that were in their drawer for many years. 

Comments like the ones our customers posted is what makes me tick!

Here are some more pictures of the new Pioneer case. I have checked that it also works well for the HP17bII+ silver (there was an uglier HP17bII+ in gold, with a slighlty curved body):

Initially, the HP Prime finance app only had the TVM solver. It was a good solver since it included everything, from number of payments per year. Good to calculate mortgage payments, but with the right knowledge, useful for many other financial calculations. Here is a screenshot of how it looked like (and continues looking since this part has not changed)

But now there are many more options that turn your prime into a complete financial calculator. To get them, you need to update your firmware to the last onem through your HP connectivity kit application.(choose the one for your operating system and then have it upgraded to the latest version by running the "look for upgrades" option in the help menu. Then connect your calculator and update it. Do not disconnect your calculator during the process)

(By the way: you can test all these features at no cost by downloading the HP Prime app in hpcalc.org, with all alternatives for different operating systems)

Let's take a look at the first menu: interest conversion with different composition periods:

The following one is more interesting when calculating investments: the date calculation app: serves to find which date is, for example, 90 days from now. It has also a provision for 360 days per year calculations, as it is common in the banking industry to calculate interest over 360 and not 365,25 days.

The following one is the cashflow app. It has two main screens: the data entry and the results. It allows both risk-free interest rate and investment interest rate, and calculates all the typical figures off an investment.

Then there is the depreciation portion of the app. Depreciation is one of the most boring parts of finance for me (as a finance manager). Well, here we have the complete palette of possibilities:

Now, you have a short app for break even analysis. (all of these calculations - and this is valid for the rest of the apps - are usually done in Excel or similar; but these are extremely useful when you are in a board room or checking someone else's hypothesis)

Then we have the percent calculations. It is surprising how many people do not understand how percentages work. ("I raise the price a 20% and then I offer a 20% discount" type of weird logic). These two pages help us. When analyzing financial statements, the one with % change and % of total is a must for quick calculations. Both numbers are calculated each time, making comparisons faster)

There are two more left. One is bonds (as I am in a production company, this is something I have never used - but if you are in an investment bank or fund, this is something you want to have in your calculator)

And the other is the Black and Scholes formula for valuation of financial products at risk:

We have received a working card reader - ready to be shipped after our tests!

Price is 130€ plus shipping, including English manual.

(comes without calculator)

I have received the second prototype of latch for the card reader. The first had not exactly the right dimensions. This second, while OK in the dimension side, does not provide enough spring action to have the latch "lock" in place. We need to angle more the leg (just like the original) so that it provides enough torque so that it latches into the calculator.

On the aspect side, it is good enoug. It will be sold always in pairs, so that no one will be able to see the difference between an original one and ours. Please email to jose@thecalculatorstore.com if you are interested on the product!

I have now several HP Prime machines. One for each of my sons (one of them using it at full power for engineering at University of Michigan), and several G1 models. I have just opened a G2 unit and updated it to the latest firmware version (20.12.2021)

I will spend some time with it, trying to learn how to program it in Python. I have take a look at the Finance app (remember that I created several finance programs, among them net present value and internal rate of return), and while in the previous firmware there was a single TVM solver, now there is a wealth of applications, including the Time Value of Money of before, but also many others, including clashflow, breakeven, black&scholes and others. You will see some of my explorations in the coming blogs too. (Note: once you click in finance and select what you want to do, you need to go to the Num part, the third key in the second column of the upper part. Then you see all the fillable fields and calculate the ones you have not filled in.)

We have sold the last unit of HP41CL. So far there are no more made and no more planned - and it will be difficult to produce more since there are many parts that are out-of -life. The board would require a deep redesign which current demand does not warrant - so it is a pity for all of us!!

One of the last units sold was a 1937A serial number unit - one of the very first. I have only seen an earlier unit, a 1932A. It is a nice closing to the story, 43 years after its inception in 1979. I was there then and I remember the lust for that powerful machine, far from me as primary student. My father bought instead a HP33c for me - which hooked me into RPN - a hook that I have not been able to unleash so far.

With the so-far demise of the HP35s, there are now the HP12C, the HP12C platinum (which has an RPN mode), the HP17bII+ and the Prime as RPN machines. So far in Europe the HP12C has been absent for some time, but I have been promised that it is returned - so far that I have been able to place an order for them. I expect the order to arrive before month end.

We are missing a RPN scientific (not graphical), preferably of small size, not competing with bigger student units. I have been given hope by the current calculator management - let's see!