Calculator blog

Musings and comments about our common interest


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More videos on graphical calculators


In continuation of a previous blog entry about a new series of educational videos on HP graphical calculators, here are chapters 2 and 3:

Chapter 2:


And here is chapter 3:



By the way, we have received two second hand HP50g calculators in very good shape: a HP50g black and another HP50g blue

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HP 50g vs HP Prime (I)

I am seeing several comments in various forums about whether the HP Prime is better than the HP50g for engineering work.

In reality, the best calculator for engineering work ever is the HP42s - provided you don’t need to interface anything. In that case, it is the HP41c daily that takes the lead. IMHO!

Any graphic calculator is a waste of screen size in my opinion (always talking about engineering work - NOT engineering studies). The only place where the bigger screen makes sense is when you’re entering a matrix (which can be entered in a more “pedestrian” way in both the HP41c and HP42s. The HP15c can also do it, and that’s the engineering calculator for someone on the road.

Once said the above, it is true that the HP50g has a more professional feel than the HP Prime. The latter has been designed to appeal to younger students. I would go as far as to say that the objective market is high school level (baccalauréat , bachillerato, Gymnasium, depending on which country you are). It has colors, tactile screen and test modes and wifi communications totally unneeded in engineering.

But the discussion is so interesting that we will try to go deeper in this subject in a couple of future blogs, so that you can decide which one suits you.

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More about: HP 50g, HP prime
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A HP17bII-type solver for the HP50g

How to effectively use the solver for your own equations

I consider the solver model of the hp17bII - hp19bII families the best there is. It allows you to perform normal calculations, but you still have the possibility of entering data at any time in on of the variables.

When using the HP48-hp50 family of calculators, this is one of the missing features for my daily operation. So I began exploring alternatives to mimic the behavior of the solver I love the most.

The typical solver in the HP50g is very useful and gives a lot of information: a screen with all the fields of the formula with their current values. However, it does not allow you to continue with your calculations, and just use the solver keys when needed, like the 17bII.

In the reference manual, there are information about many hidden menus. One of them is MENU 75. It goes to a submenu where there are some solver related options.


The first one leads to a soft menu where the keys are the different variables of the formula stored in 'EQ'. You have a glimpse of the formula in the upper part of the screen. So, you just need to store the formula in 'EQ'.


How to automate it just a little bit more?

We can prepare some "programs" that lead to the solver formulas that we want. This is what we did for the financial calculator:

<< 'Formula' 'EQ' STO 75 MENU >>

A significant difference over the series 17bII solver is that the latter calculates the value of the variable when you key on it after having keyed on other variable before. So it knows when to solve.

With this menu system, you enter the variables the same way, but in order to solve, you need to left-shift the variable you want to solve for.

Once you get the idea, you can live quite well with it! Now I use it for most of the normal daily functions. Actually, it is easier to select the program by browsing on the variable list, than going through the list of entered formulas in the 17BII solver.


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Yet another Easter egg in the HP50g

There is yet another Easter Egg in the HP50g. Apparently, the one shown in the previous blog page is the latest, appearing only in ROM versions over 1.18. This one apparently appears in all versions, but looks as a more primitive version of the game. 

You need to write "HpMad", between inverted commas and within an entry field in any form - even the beep "tick" of the modes menu works. See the screenshot below:


You then will get a tetris screen in landscape format. (if you use the computer emulator, it is exceedingly fast and not fun at all to play with). The pieces are much more elementary, and the aspect is rougher than in the other Easter Egg. I am putting both here for comparison. You'll choose which one to use!

screenshot.67.jpg screenshot.63.jpg

When you finish the game, you will be rewarded with your score in the same command line you abandoned shortly ago:


(I told you that the screen was moving too fast for my slow fingers - I was not able to score a single line!)

There is another easter egg in this calculator. This time is a little bit less useful: it just show a puzzle with the names of the developers of the HP49g calculator - at the time it was under Australian Calculator operation (ACO) team. You need to write RULES and press enter, and you will see this acreen:



Easter eggs seem to appear with some frequency in mainstream software. In some programmer ambients, you cannot possibly release a significant piece of software without including these.

In a previous blog installment, we incuded a video with a chronometer in an HP45. The Easter eggs in HP calculators seem to have existed since very early in their history!

Googling for HP Calculator Easter Eggs will give you 480.000 results. It seems that this is not only existing, but as well interesting enough for many of us! Not only calculators, but also the HP 54600B oscilloscope has a Tetris inside. 

In the company I work in, the AS/400 software development is under my responsibility area (although I am not directly related with programming or analysis. We are not a software company, just a AS/400 user with volume enough to do our own developments). I wonder if our developers are playing that kind of games in our much more serious business software...

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Tetris in the HP50g

This is one of the times you feel stupid. You think you know quite well what you have, and there comes someone that shows you know nothing. 

Today, at work, I was using my HP50g, and a companion said to me: "wow, that's the calculator that comes with Tetris". 

"You mean you can load games, do you? of course you can find a lot of games for it", I replied.

"No, I mean that it comes with Tetris in its software", he said.

"I don't think so".

"Try this: open the formula editor (right arrow + EQW), set alpha, and write MINEISBETTER".


"Now, select it:"


"and now, de-select alpha and press "SIMP" (F6). Voilà!!"


You play it with the keys 2, 4 and 6 for movement across the screen, and 5 to rotate. Backspace to stop it.

Again: all the time in front of my nose, and I did not know!!

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Why using a handheld calculator nowadays - part I

Many people, when they see me using a calculator in my job, argue about why using now a calculator, when there are so much more powerful alternatives. They always try to convince me about how much better is a spreadsheet, etc.

Let me try to organize my thoughts about what's the point of having a calculator nowadays, when we have computers and, let's not forget, smartphones. If you are reading this, chances are you are as nut about calculators as myself, and you are as well faced with those questions from time to time. I hope then I can give you some elements for discussion. I would like to ask you to post your own reflections, to reinforce my arguments as well.

(Other times I get challenged about collecting calculators, but for that, to be honest, I haven’t found any good argument in our defense!!)


In order to systematize the discussion, let’s see first which are the most likely alternatives to your calculator (the most likely, not all of them. Remember the HP-01? Or more typically, the Casio watch calculators?)

  • PC running spreadsheets
  • PC running specialized mathematical software (Vgr. Mathematica)
  • PC running a calculator program
    • The operating system’s own calculator
    • Emulated “true” calculators
  • Smartphones
    • Own calculator
    • Calculator Apps
    • Ipads and other tablets

In this post I will deal with the first ones, leaving the others for a further post

PC running spreadsheets

On one side, it is true that an spreadsheet carries you further and with less effort - and it leaves a trace of what you are doing. You don’t need to write with your pencil the intermediate results.

Today spreadsheets have very powerful instruction sets. And it is very likely that what I now think that can't be done with spreadsheets, is more due to my lack of knowledge of the tool than actual lack of that feature. I am now thinking of all matrices-related things. 

PC running a mathematical software (like Mathematica)

I have to be honest with you – the last time I used one of these, I was still using MSDOS, when I was studying engineering in the 80’s. For me, this option is limited to Academia – which is the environment that would buy and maintain this kind of software. I have to confess that my opinions on this area are based on very out-dated information, and I cannot add value. (here is where you, reader, can join in!)

Before the IBM PC was born, there was a Personal Computer produced by HP – the HP85. It was a fantastic machine, running a BASIC-oriented operating system, with a big number of mathematical operations for the time, and that could be programmed for any kind of mathematical challenge. In this case, some of you could tell me that it was not an alternative to calculators: it was, in fact, a calculator (its CPU was based on calculator CPUs, at a time where 6502, 8080 and Z80 microprocessors were common on other machines)


There were ROMs that enhanced its capabilities in areas that are the realm of calculators: matrices, etc.

PC running a calculator program

I am running in my Mac a couple of different HP15c, a HP42s, a HP41cx, and under the Windows screen in parallels, a HP50g. Even the most advanced scientific calculator (the wp34s), started its life based on the SDK of the 20b  - if I am not mistaken. I have written a blog article for the humble Mac OSX calculator, that can be configured as RPN as well.

The choice would be even bigger, were I running Windows as main machine. I have not explored the options for Linux. I might be interested if I still was in the Windows camp, but I moved to Mac and I’m not thinking about changing again.

The discussion of the many working alternatives for calculator programs is well beyond the scope of a single post, and deserves an article or a series of articles from somebody much more knowledgeable than yours truly. Let’s focus instead on the advantages and disadvantages:

  • Advantages:
    • Speed: several orders of magnitude running programs, except in case of the latest calcs, like the wp 34s, hp 50g and hp 30b
    • You can have all the options – you are not limited by memory or bays used, like in the HP 41c family, or the HP71b
    • In most of them, the numeric keyboard works as well, as most of the basic operations. The keyboard shift works as F.
    • In some of them, there are side windows that can show the status of the internal registers, from seeing the whole stack and last x registers (good), to seeing all the CPU registers and flags (geeky).
    • You can take all your calculators with you, instead of being limited to 2 or three. (I seldom travel with 2 calculators – most likely I take 3 with me: the hp 15c in my jacket pocket, the HP17bII for calculating at work, and either the hp 50g or wp 34s for fun at the hotel.

  • Disadvantages:
    • You need to switch on your computer, and then you need to look for the application and switch it on as well. This takes 1 minute – unless you’re working with Mac – then you’re going after 16 seconds. Let’s see what Windows 8 brings to the table.
    • In many cases, the calculator does not keep the state you left previously: stack and memories. This is not really a problem of the idea but of the implementation.
    • There is no comparison between keying in in a physical keyboard and doing it with a mouse.
    • It occupies real estate on your screen, the same as a calculator occupies real estate on your desk – however, screen estate feels always smaller and cramped than your own desk. (by the way, this is the reason that my HP19bII never takes a lot of use – same as with the HP71b.
    • If you are using it in conjunction with Excel or other program, the switch from one to the other is never instantaneous – you need to click twice on the window – once to select it, another to start doing what you wanted. This happens between any two windows applications, by the way. 

There are times when you can’t use a computer – meetings!

There are two kind of meetings in my company: with and without computers. When you see a meeting where everyone is using a computer, you can assert than more than 50% of the attendees are not really there, but emailing or finishing their presentations for their turn. Therefore, they are not listening to what whoever is speaking has to say. 

More and more, some managers are insisting that laptops are closed while the meeting takes place – at least, while they are speaking! Therefore, the calculator is your only alternative to number crunching during a meeting. 

As well, in a meeting you need to give a fast answer, and this would be difficult with a computer. With a calculator you can do fast and dirty calculations; with a computer, you lose and inordinate amount of time formatting even the most minute calculation. There is a brain switch that allows you to take approximations and shortcuts with a calculator, but impedes all but a perfect mathematical model when you try to do the same thing with Excel!

As conclusion of part one: it is not clear at all that a computer can take all the work a calculator does. Let’s see in part two what happens with the other devices mentioned at the beginning of the article.

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Back from holidays...

Just returned from holidays and still no news on pricing o0n the long-awaited new products. The in-tray is filled with enquiries on one of them - guess which.
Some of the incoming email suggests some ideas for the website. Some of them have been implemented, some of them interesting and worth trying. 
One of them is intriguing and I would like to ask the readers whether is a way to go or not. It is about upgrading to higher models.
Of course, the malfunctioning units would have no room in the system. I am thinking on getting discontinued calculators in exchange for new ones (+ some money to discuss, depending on age, state and model). This would be limited to top models (one of the new coming models, the 50g and the 17bII - maybe as well for the upgraded wp34s)
What do you think? please email to with your comments!

Just returned from holidays and still no news on pricing o0n the long-awaited new products. The in-tray is filled with enquiries on one of them - guess which.

Some of the incoming email suggests some ideas for the website. Some of them have been implemented, some of them interesting and worth trying. 

One of them is intriguing and I would like to ask the readers whether is a way to go or not. It is about upgrading to higher models.

Of course, the malfunctioning units would have no room in the system. I am thinking on getting discontinued calculators in exchange for new ones (+ some money to discuss, depending on age, state and model). This would be limited to top models (one of the new coming models, the 50g and the 17bII - maybe as well for the upgraded wp34s)


What do you think? please email to with your comments!

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More about the Multi-Language software for the HP50g

I have received today a message from Andreas Moeller, an innovative programmer, and author of a set of tools for the HP50g.These tools include a full translation of menus, flags, and applications to the language of your choice, and an equation tree builder which is extremely useful for those that have several equations and several subdirectories in their HP50g.

(by the way, a disclaimer - we sell the HP50g with the multilanguage as a pack - and we include with it an SD card)

Andreas has been working to make its software known. We have a difficulty here: it is hard to convince a student to pay for something when he is accustomed to get everything for free - and students make 95% of all purchases of HP50g. (users are more varied - eventually the student earns his grade and starts working, keeping his calculator with him). One way he has trie is creating some videos that explain how the software works.

Here is the example about the multilanguage pack:



Equation Tree Builder

I am enjoying the full set of tools in my HP50g. It is saving lots of time in my work. When I need to find where is the nice equation that I wrote 6 months ago (how did I name the equation? What did the variables mean? Under which assumptions does the equation work?

Here is a video that shows how the tree browser is used



You can even organize your own sets of equations and transform them into programs, or even libraries, to be distributed to your friends and colleagues. Here is a video that shows how:



All in all, an excellent software, and for me (in particular the treebuilder), verging on the indispensable. Highly recommended !!

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New HP50g vs Classic 15c

Classic HP15c vs new HP50g

I see the old HP15c derided by current users by comparing it with HP 50g. They laugh at the specs, the screen size, the programming model, etc. They wonder how mint units can get over 300 € on ebay and other sites.

I have both. In my common work, I use the HP 50g. I can see everything that I have done - sometimes I need to clear to unclutter the stack. However, it is clear to me that it is not a calculator for all purposes: I cannot take it to meetings, or when discussing with a colleague some alternatives, etc. For that, I have in my jacket the HP15c. (For that matter, I could use the HP42s instead - however, it takes longer to navigate the menus and do what you want than on the 15c)

The HP 15c is the unit I take with me in airplane flights, to discussions, when going out shopping, etc. (whenever any of you would make a calculation in your iphones, I'm done long before with the 15c - with the advantage that I can tall the result to the person on the other side of the phone!)

In the past, when there were comparisons with the hp 41c, I/O was a factor - no more (infrared is not often used, since sales of infrared printers are so low, and there are no instruments that can interface with the HP50g, save for the streamsmart model, which is a high school application with no professional instruments to attach.

The programming capabilities of the 15c are more than enough for most business or engineering problems, due to its extense function catalog. There is as well the fact that it will last forever with a set of batteries, while you need to change the 50g batteries every two months id you use it frequently.

If I have both at hand, it's the 50g that I take. If I have a program to do, or solve an equation, it's the 50g I turn to.

I do not want to choose - I want both.

I heard rumours that you will not have to choose, too.
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More about: HP 15c, HP 50g