Calculator blog

Musings and comments about our common interest


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The HP19BII back door


The HP19bII hits a sweet spot in me. It was the calculator that was recommended when I took my MBA after engineering school. (The HP17bII was the other, cheaper alternative). It had everything the HP17bII had, plus 3 lines on screen and a more populated scientific menu: it included everything an engineer could need, short of matrix algebra: several conversion types, probability, trigonometrics and hyperbolics, etc.

The problem of the breed (common to the other clamshell units, the HP28 family) was the design of the battery door. The batteries placed a lot of stress on the door, and this force was supported by a limited area. When the calculator fell on the floor, the door usually broke down. Also, the plastic used was quite brittle compared with other models, making it more fragile over time.

At some point in time, there was a redesign to bring the battery door from the side to the back, solving the universal problem of the side door. In my opinion, also the plastic is a different formulation, softer and more flexible. Looks darker, too. The keys are black instead of grey:












And here you can see the back of the calculators (anf the different plastic color):


We have solde several units, but this one is for me! (By the way: I received one without the door, so we designed a 3D-printed door for the back door HP19bII - please contact for info if you want!

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HP 17bII+ vs HP19bII


I have been comparing the HP19bii with the HP17bII+ for the last few days at work. Have to say that it was a fair fight - both units are really very good.



  • several lines on the screen allow for clear interpretation of what you are doing and what you need to do
  • when you need to enter a solver formula, the attached keyboard helps you in doing three or four times faster than the 17bii+
  • Very good keyboard that never misses a beat.
  • nicer font (in my opinion) than the other machine
  • Fantastic menu system.
  • additional math items: trigonometric, hyperbolic, unit conversion, etc.
  • When folded is pocketable. No more losing the calculator case!
  • Graphs (but I have never used them!)


  • Too much real estate taken from your desk
  • Half of it is not used at all most of the time!
  • screen contrast is really low. You depend on good lightning conditions.
  • Problematic battery bay door - unless you have the back door model.



  • Much better form factor.
  • Elegant silver design.
  • much better screen contrast - black is black!
  • Currency exchange on first menu level
  • Better key feel


  • Just one line seen on screen
  • Good font, but not as nice as the competition above.
  • Sometimes, I’ve missed some keystrokes. Not often, but it is different from “never”, which was my experience with most other HP calculator.

I hope this helps in selecting the right one for you!

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Two new old HP19bII

Just a brief reminder that we have two units of hp19bii available at the shop. These are wonderful machines (see my thoughts on this model here and here), with just the problem of the side battery door. Sadly, the back door model is much more rare, sought after and therefore expensive.

As many of you that have calculator collections, I use some at work; and again as many of you, I don’t use always the same one. I have been using the hp prime as of late, but after reading the fantastic HP19bii manual, I have taken my collection piece for this travel week. In my opinion, it has the best set of functions for an industrial company manager. Apart from all financial calculations, laid out in the best menu-driven system ever designed for calculators, there are other very practical functions:

  • Currency exchange (this is common with the last version of the hp17bii, that can be had in brand new version)
  • Unit conversion between imperial and metric. It includes the most relevant for a business person: length, area, weight…you don’t really want your daily calculator to perform cv to kW or energy to BTU conversions, do you?
  • Time. Apart from date calculations (number of days between two dates, etc.), it has a clock and a calendar and can be used as a true alarm clock. You can set several alarms, but it won’t replace your telephone as time manager. That could have been the case 30 years ago, but not now.

You can find the two units here: HP 19bII - USADA

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Más sobre: HP19bII
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More HP19bII

DSC_8949I have received a new HP19bII and was remembering what a wonderful general-purpose calculator it was! If you are not a student or academic, and you are a businessman or engineer, not having to do many on-site extremely complicated equation system solving or matrix work, the HP19bII has everything for you. Really!

Only in the last iteration did the HP17bII get a currency exchange menu. Well, it has been there in the HP19bII from the start! Also, there has been no general purpose calculator that had units of measure translation - you needed to go to RPL graphical calculators. Again, the HP19bII had it!

Time calculations and a true clock, with easy-to-set alarms and messages? check; A complete alphabetic keyboard (albeit in an awkward format)? check. The most complete set of financial and comparison calculations, in a menu format and seeing the three previous results? check. Statistical 2-variable, list based functions (as opposed to a set of registers getting accumulated data like it had been in the previous, non alphanumeric calculator)? check. And it handles also NPV and TIR in intelligent ways, using list of flows and times these flows happen.

The only grips I have with this calculator are two: the huge amount of real estate it takes on your desk, most of it not utilized during most of the time; and the very poor design of the side door for the batteries, although the latest model had a door on the back, which negated this - but these are few and far apart, and have a different price altogether). Being a little more picky, the contrast of the screen is not so good - more so compared with the latest HP calculators.

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RPN and the HP19bII

There was an interesting discussion lately in forums. Has RPN crippled you for other calculator methods? Are you able to reasoning calculations in another way? Can you use comfortably another calculator for any extended period?

I, for one, started off with RPN calculators when I was 12 years old. My first calculator was an HP33c - the second simplest model in the Spice lineup. Before that, my dad had taught me to use his HP37E financial calculator. I am pretty sure that he didn’t go much farther than using proficiently all % functions. I don’t think he ever mastered the TVM functions. At least I never saw him using them, or explaining them to me. In retrospect, it was a huge pain to have a calculator without permanent memory (all E version lost their memory contents when switched off)

At that time, calculators were not too popular at any student level. Most of my classmates didn’t have a calculator at all, and any who did, had the lower level Casios. I learned the calculator with the excellent user manual provided. The examples and the logic behind was unrivaled at the time; only with the hp85 personal computer I have seen a better package.

In class, the RPN calculator alienated most of my classmates. They would ask me for it in the middle of a test, only to come back to me in anger asking “where’s the equal sign!”. I learned to tell them in advance that they would not be able to use it. (While RPN is extremely easy to learn - you can get the beauty of it in just 15 minutes - a test situation is not the best environment to learn it!) On the other hand, I soon became completely unable to perform chained calculations with a “normal” calculator. And at that time no one had a programmable calculator: none of my teachers would know what that meant, or were able to identify one. So I had an undue advantage in the first courses, since I was able to program small little programs for the tests (with its very limited 50 steps; but I have been able to program a Net Present Value program in just 24 steps of the hp15c)

Later, when I started engineering, 5 years after, the calculator still was working - a testimony to hP’s engineering and quality of yore. But then the battery bay broke, and I needed to get another calculator. At that time, the one to get would have been the hp41c - but it was very far from my reach. So I ended up having a Casio 790p - a Basic-programmable machine, which had a couple of weak points but mostly got me through engineering. I was able to program in it all that was required in engineering - in particular equation system solving through matrix inversion. Now it seems all so easy, with most graphical calculators proposing it as a basic feature; but at that time, you had to program it for yourself! Be aware that, at that time, all numerical methods were taught in FORTRAN, to be run in a VAC computer. So I still was at the programming forefront. And, amazingly, the 2kb memory limit never was a problem. Later I have been using the hp71b, which is a better machine - but surely not ten times better, as the price would suggest.

With the Casio, I never managed to chain calculations the way you easily do with a RPN machine. Fortunately, I just needed to write the whole expression and evaluate -the same way it is now done in the Prime or HP50g textbook mode. But my mind was still wired for RPN.

Later, when I started my MBA in Barcelona, the Casio started to fail by its hinges, and I had to get another calculator. At that time, the right choice for business was the HP19bII. You could use it both ways: algebraic or RPN, but I always set it for RPN. (The fantastic solver was - and still is for its sibling hp17bii+ - a textbook entry concoction). I am still fascinated about this calculator. It was the first financial calculator that included trigonometric function, and even hyperbolics! Not only that - perusing the manual, I even saw measure conversions. It was the universal calculator of that time for anyone in business - provided he was not a pure technical person.

We will elaborate more on the HP19bII tomorrow.

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Más sobre: HP19bII, RPN
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New units coming in

Several news in our products:

  • There is a new boxed HP41CL in pristine state. The screen is not yellowish, the box comes with all manuals and even the stickers for your overlays are there! Pictures will follow.

  • We have also a very good, side-battery door HP19bII, with original manual in French.

  • And a new HP42S, just received. The bezel has some nicks, but barely appreciable. I have been playing with it, and it has warmed again my heart to it. RPN at its best, without its problems (try to use matrixes in any other RPN calculator, except the HP15c)

I will post all three in the website as soon as I can take the corresponding pictures.

On a different subject: we are quite sad to not being able to offer a good transport arrangement to our overseas customers. Even shipping outside the European Union is getting increasingly complicated for small shipments like ours. In the past, we were used to close to no paperwork. Now, with tax administrations trying to get resources from wherever they can, procedures are much stricter and therefore expensive. We will have to increase substantially shipment costs to the US

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HP17bII as the best all around financial calculator

DSC_8948I have been using during this Christmas period the back door HP 19bii. I had left it on my desk at home, and it was at hand when working from home.

As you all know, the main problem with the Charlemagne Clamshell HP calculators is that they fail always in the same weak spot: the battery door. The batteries make pressure to the door and, with the plastic getting brittle with the passing of years, it will eventually break. The cure is not easy, and never beautiful. It surprises me that this calculator model has never failed in my experience by the hinge that keeps together both parts of the clamshell - all moving parts are prone to fail. Nevertheless, a failure there is not so critical. Unless you program with the solver, you can live with just the right part of the calculator (someone could argue that the HP17bii is just the right part of the hp19bii!)

Sometime ago I found in a shop a Hp19bii that was not boxed, like the original ones, but in a blister, like the new ones. This packaging looked cheap, but within there was a calculator where the main problem had been solved: the battery door had been moved from the side to the back!

That wasn’t the only change. The plastic seems to be softer than the original one; the color is also more black than brown. The keys are alright. Screen contrast is like all old hp19 and hp17 - quite bad for current standards. Comparing a new 17bii+ with an old one is a joke when it comes to contrast.

If you’re used to the hp17bii, then you know how good its menu system is. They wanted to test a new menu model in the hp30b, but it wasn’t nearly as good. And if you’re used to the hp17bii solver, then you also have it there.

Common with the hp17bii is the fact that once you are at a menu level, you remain there until you press exit. You don’t need to start the whole menu excavating process for each new repeated calculation.

But the screen is so much better with three lines in sight (compared with the one in the hp17bii - and a much better font.

You need to factor in several other details:

  • Writing solver formulae is much easier when you have an alphanumeric keyboard than when you need to click at least twice for each letter, when navigating across letter menus. Despite the fact that the HP19bii keyboard (as the one in its scientific siblings) was ranged in alphabetic order, it is still clearly better than navigating through menus. Hp solved this isue giving the HP71b a nice qwerty keyboard. But apparently still thinks very low of the people that prefer this kind of keyboard, for even the latest Prime calculator has the alphanumerica keyboard arranged in alphabetic order.
  • You don’t need a calculator cover: the clamshell does work - more so when the battery bay cannot be easily broken.
  • You can even have simple statistical graphs.
  • The hp19bii comes equipped with a complete set of mathematical functions. Not only trigonometrics, but even hyperbolic functions! Not at first or second keystrokes, but nested in the menu system.

You can find such Hp19b version (together with an English manual) here

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Just received the HP67 !!!

Just received the HP67!


Believe it or not, it is my first HP67. I bought it as a pack with an HP19bII without door, for 130 €.


(I know that it is quite difficult to find good condition doors for this model, but there is this thread in that gives us hope for this otherwise magnificent model – the only calculator before the 30b that had a complete set of scientific functions in a financial body, but with a much better user interface.)




Coming back to the HP67, I need to test it thoroughly. I have spare magnetic strips (to be used in the HP41cx reader), and I plan to test it tonight. I do not care that it does not work – there are plenty of resources to repair the gummy wheel syndrome that most calculators develop.

The seller warned me that the batteries would be flat and unusable. The good thing is that the connectors look shiny – proof that the acids have not leaked out.

The machine comes without a charger, but I have some in inventories. The pictures sent showed the machine working – let’s see it tonight.


Once connected, the machine works. Some keys are a little bit sticky – let’s see if there is a cure for that. I have now changed the batteries for spare new ones. I will leave the machine charging the whole night and see tomorrow if it holds the charge.

I have cleaned it with the normal computer cleaning kit – it looks now much better!

Used to the different LCD screens, to come back to the red LEDs of my infancy brings warm feelings to me…

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Two different types of HP19bII

I have now received another calculator for the "harem": an HP 19bII with the back door. 

I have fond memories of the HP 19bII. While my first calculators were HP (spice models, beginning with the 33c), I did my last 3 years in university with a Casio pocket computer. At the time, I did not have the funds for the HP41cx - which was the model to have. However, for all practical purposes, the Casio was a better calculator: it could be programmable in Basic and I could do any numerical programming I was asked in my engineering courses. While I missed the powerful Basic of the HP85, with which I made my first money, it was good enough for me.

When I finished engineering I started an MBA. I then got some more money, and I bought the then best available financial calculator - the HP19bII. I enjoyed it during 2 years. It had all the financial tools, plus a good set of statistical and mathematical tools. However, at the middle of my second year in the MBA, it fell to the floor and the battery door went off. I was not able to fix it properly. Tired of sticking it with tape every now and then, I left it in a drawer (from where it was picked up by my sister) and got an HP 17bII instead. A classy machine as well, but missing key features like trigonometrics. Well, it was more than good enough, but it market my end as a self-respecting engineer.

Several years later, when at a covneience store in Madrid, I saw a stack of blister packed HP19bII. They looked blacker than I remembered, but at that time I was not looking for another calculator, and I passed by. I did not know at the moment that I was looking at the back door HP 19bII.

When I started collecting calculators again, the 19b was one of the first to get. I knew what to expect: a well specified calculator, with all the functions I could need for a non-academic environment (seriously, how many times are you inverting matrixes in real life?), but I knew as well that it should rest on my desk most of the time, unless I wanted to have another battery door casualty.

I have just bought a back-battery door HP19bII. I guess that many of you would like to see both kinds compared:


Front view: the back battery door on the right. It shows a darker colour, but the difference is not too big.

Here is the reason for getting it: the back door:


The batteries were set in place with the door, but there was pressure on the door all the time. Whoever changed a set of batteries onthese machines know what I am referring to. This design change solves the problem (at  least, this problem!)

The keys have the same good key feel - totally different from any other HP but very satisfactory. This sample was made in Indonesia.

The keys are much blacker than the original:


A closer look:


Now that I think about it, I have not tested it for speed differences - and I will not do it today. I keep most of the claculators in the collection without battery, to avoid corroding the terminals, and to do these tests I would have to go through the painful exercice of changing the batteries again...

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Suggestions for a change in HP17bII+

Due to my job I have to use more often financial calculators. Due to my education, I am more inclined to scientific calculators. Of course, I want to have both.

I have (as many of you) several calculators that I use frequently. 

I love the menu scheme of the hp19b and hp17b families. If you are not into maths but business, you can't go wrong with either of them.


(Picture: the HP17bII family)


And the HP19bII


I love the 3 lines of the stack in the screen, that allow you to see what you had been doing before (why the HP17bII does not act like the HP42s, where you can operate with both lines showing x and y registers?)

But more than these additional lines, I love the additional math-related menues, that allow trigonometrics and even Hyperbolics. With these, and wihtout the need of doing complex programming (I mean, beyond what can be provided by the very powerful solver), I can live with the HP19bII for nearly all my calculator needs.

Fact is: the 19bII is quite cumbersume and uses a lot of expensive desk real estate. Moreover, it uses N-type batteries, which are expensive and not found everywhere.

The question is: would it be too difficult to enhance the math menues of the 17bII+ with the additional math functions provided in the 19bII? There are no changes to be made on the body (which is very good on keyboard feedback when compared with the previous model, and on par with the new one), and not even in the key layout.  It is just redesigning the math menu (perhaps with an additional depth level) to take care of these.

I know that the current versions use different processors and therefore it is not a direct port - but probably current software is as well emulated in some way. 


This would help to keep the HP17bII+ at the top of the financial food chain. Now, there is the menace of the 30b (with much lower apparent body quality, but programmable and with Black&Scholes functionality) and even of the lowish HP10bII (wich is a fantastic calculator, except for the lack of RPN.


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