Calculator blog

While preparing some explanations on how to use the TVM feature of the HP12c, I found a disconcerting difference:

Loan calculation: monthly payment, 200.000€ initial amount, 20 years, complete payment, 6% annual interest, END mode. In brackets, actual keystrokes.

n => 20*12 = 240 [ 20 g n]
i =>  6/12 = 0,5% [ 6 g i ]
PV => 200000 [ 200000 PV]
FV => 0 [ 0 FV]
Calculate monthly payment: [ PMT ] => -1432,86 

Loan calculation 2: with the above data, how much will it be left to pay at the end of year 10 ?

n => 10*12 = 120 [ 10 g n]
Calculate future value with same interest and payment: [ FV ] => -129062,84 of principal. 

Loan calculation 3: how much have we paid of interest and principal in the first 10 years:

Follow the loan calculation 1 steps to make sure everything is in its place with the original numbers;
[ 120 f AMORT] => -101006,34 (interest paid)
[ x<>y ] => 70936,86 (capital paid)
Pressing now [ RCL PV ] shows what is left to pay: 129063,14. This number is different by 0,301 to the number above. It however adds up to 200000 with the capital paid above.

This took me a long time to understand, and I also checked with other calculators: the original 12c, HP17bII+, HP19bII...all of them reproduced this difference.

I ended up asking Gene Wright, probably the most knowledgeable in the crossroad of HP calculators and Finance math. He came back with the most likely explanation: the calculation depends on how many decimals you set. I had set 2 decimals for the HP12c, and the firmware takes that as the exact amount paid in each monthly, payment, not using the hidden accuracy of the full mantissa. This was proven by setting the number of decimals to 9: both calculations coincide.

There is an additional comment: the AMORT calculation for 120 periods was instantaneous in the latest HP12c, but took more than half a minute in the original HP12c !! I was not used to wait ! I will now continue with other HP12c features, like IRR and NPV

After the HP41 Corner and HP Prime corner, we have also created a HP15c corner.

In this area we will include HP15c programs, HP15c second hand that cross our way, HP15c accessories (like our loved true leather cases), and ... whatever comes in the future.

I was informed by Monte Dalrymple that he has sent HP41CL modules to production again. Apparently these can be here by August - so back again the most powerful tru RPN calculator !!!

Apparently, no changes in performance. I will order only units equipped with Time Module. Please connect to sales@thecalculatorstore.com if you are interested in getting one !

I have been using the new HP12c for some time already. My main challenge with some HP calculators of late has been that, while they "click" quite well in all cases, there are some odd cases where the click does not register as keystroke. This has happened with the old 12c, 35s and 17bII+. I guess that it has to do with the settings to avoid the rebounds, and that 's a fine line to be walked lightly to avoid double strockes or missing strokes. 

This is of key importance when using the calculator. You need to be confident enough so that you can key numbers without looking at the screen. I have not been able to do that with most of previous HP calculators.

Not with the new model. Key registration has to do with the firmware (unchanged compared to the last version) but also with the quality of the hardware. This edition seem to have sorted out these quality problems and I am getting exactly what I am keying in.

(It also behaves well when reprogramming the unit to another Voyager model)

I have been using the new HP12c model that we opened in a previous blog issue. As financial user, I an drawn to the HP19bII back door that is on my desk, but when I travel (quite often), it is too big a calculator to move around, and to lay on a desk. It just uses too much real state. The HP17bII+ is better in that regard, but just slightly. There is something about landscape calculators that make them more suitable for every day work on a real table with a computer and several screens and papers.

Coming to the calculator, it seems to me that they have nailed it. The click of the calculator seems one of the best of the last 30 years, and so far it hasn't missed a stroke. This is very important: we need to be able to key in without looking at the screen, being sure that everything is being recorded as we key. This has not been the case in many previous calculators!

The bezel is real metal, as opposed to the previous model, that seemed plastic looking like metal. This may have the problem that it will receive scratches - but so be it for good quality bezels.

These calculators have also a contrast control - however, it seems to me that there is one step from where it is too little to another just fine. Going darker does not improve.

For the sake of checking, I have entered a HP15c firmware with the programming cable (you need to modify yours, since this one uses the USB protocol) and it works just fine. I just cant wait to see what other calculators can be developed using this hardware base! We can even foresee keyboard overlays to be able to use other calculator models, like HP15c or even HP16c - with the same basic hardware.

(note: some pictures will be re-taken with better light)

As it has been said many times, this approach to the HP10b was a complete success. They started with the proven ATMEL ARM-based core used also on the HP12c, and they programmed it from scratch: not just applying a firmware layer on the Saturn emulation core they have used elsewhere, but they created a native firmware. This makes it the fastest HP calculator extant - what a pity that it is not programmable. (The only other drawback that we see in this calculator is that it is NOT rpn: only algebraic and chained).

It has plenty of functions, including some mathematical ones that evaded any other financial calculator so far (bar the HP19bII of 30 years ago): trigonometrics in radians and degrees (including inverse and hyperbolic, in a "tour de force" that no financial used will ever appreciate, as far as I can imagine), permutations and combinations, natural logarithms and e^x, y^x, n!, Pi, and more.

It comes in a blister, inclding a couple of guides for different sets of languages. These sets, while not a guide like it used to be, are far more informative than the very simple page in the new HP12c. At least you get a picture of the calculator and a scheme of the parts of the keyboard. However, there is no excuse for not downloading the full manual.

The back of the blister is also multilingual. The advantage of this packagings is that it is a single one, worldwide. Easier to manage and stock - just one SKU. (By thew way, it also explains what is the license situation of the current calculator line up)

The protective case looks better than the previous model (new: right, old: left). It has volume and a better feel, much like the HP12c's. The previous one looks like pure plastic.

The calculator has a very clear screen:

And finally, the back side with the now-ubiquitous screw securing the battery case:

I just wanted to compare the performance of the just arrived version of the HP12c with the latest one, running the 2015 firmware. 

Both units are different from the original one (and around 150 times faster) but also different from the so-called HP12c+ that was produced around 2008. Both have an Atmel ARM-derived processor, but the newer model is far less energy consuming. Both can be reprogrammed (if you have the right firmware) and have the same connector, but the former used a different pin scheme, while the latter's protocol is USB (albeit with the same POGO-bsased connector).

I have run the simplest of programs for a minute:

01. +

02. GOTO 01

Both have exactly the same speed (within the accuracy of my finger starting and stopping the count). Notice the lack of "Hewlett Packard" in the lower part of the keyboard plate. We have just received a batch of the latest model, as well as units of the other current HP models. 

We are now opening a brand new HP12c unit. We will post some pictures and compare it with the previous iteration.

Packaging is thinner and hence cheaper for shipping. It includes a case behind the quick guides:

The quick guides are multilinguals and foldable, in line with other machines. They show only batteries, statutory information and starting the calculator, and a link to the site with the manuals - really nothing else !! You have access to the complete manual in hpcalcs.com. You really need them: the foldable quick start guide does not even say that HP12c is RPN, nor guides you on the simplest of calculations, let alone give a glimpse of what your machine can do. Download the manual NOW!

The back shows the screw that secures the battery bay cover. I will not sell any other battery cover since they won't be needed !!

Here you have it compared with the previous Philippinean iteration. Main differences are: the bezel is metal (opposed to something that looks a little like metal, but feels like plastic in the previous unit), and there is no "HEWLETT-PACKARD" label in the lower part of the keyboard.

(The right one is the new model). And here, the backs compared (upper old, lower new)

Bonus: comparison between HP12c case (latest) and our own brown true leather case:

The new HP models have arrived to Europe! This is the first lot oredered through the new license scheme from HP, with Moravia and Royal as licensees. These models have a screw securing the battery bays, due to regulations in some countries. The looks otherwise are the same. I will do some unpacking and show it here in future installments.:

There are two current models that are firmware re-programmable. One is the HP10bII+; the other is the HP12c. 

The HP12c is probably the most attractive to repurpose, because there is already available firmware for several Voyager calculators for several other models.

Both HP11c and HP10c are not too interesting, since why load them when you can load the HP15c - and what's more, there are versions with 3 times more registers or programming steps?

But what about the HP16c? this is a model intended for the Computer Scientist. It has not been reissued unlike the HP15c. And yet it fills a gap of fast operations in different number modes. These can be done with the HP48 family, but it is much more cumbersome than doing it with the HP16c. 

So it has been done:

The problem remains with the lettering. The easy way is to take a photocopy or print out a HP16c picture at full size, and then paste it to the calculator with a transparent tape for packaging. 

We have been considering creating a sillicone cover that would have a better aspect and mechanical feel: