Calculator blog

Musings and comments about our common interest


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Next Step: the cable!!

It is no secret we are developing a cable for the now-standard HP calculator connector (which appears in the HP12c, HP15c and the HP10bII+ calculators)


It is difficult because it does not have a standard 2,54mm pitch - but we will find a solution. With it, we can foresee fixing any bugs that are in current firmwares (so far, nothing in the "main" firmware, but something in the NOMAS part)


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Overlays again

We need to state some things clealyr regarding our overlay:

This is NOT a HP product

The HP16c mode in HP15c CE is Not Manufacturer-Supported. HP and its licensees are not responsible for its use and suitability for any application, and for the bugs that may exist in non-supported modes. The user is solely responsible for the operation in non-supported modes.

This overlay is intended just for exploration of the calculator features and not for professional purposes, and it is designed and produced by The Calculator Store SLNE. The company makes no representation for the accuracy of calculations in HP16 mode, in particular due to the DEC display bug.


Now working on:

  • A firmware update that caters for the mos egregious bug in HP16c : the DEC bug. (I do not want to brag about it, but it was I who discovered it first). There are already candidates to solve the DEC bug - but not the others (very minor in comparison)
  • A cable to perform firmware updates: the 3D design is made, we need now to perform mechanical tests, andf then submit to production
  • Captura_de_pantalla_2023-10-18_a_las_17.40.02
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Overlays, cover, etc.

We have received several questions about the Overlay option in the HP15CE - so many that we have changed the name to "Cover". 

It is an HP16c overlay to be put on top of the keyboard. It allows the machine to behave as an HP16c if you have the means to transfer there the firmware of an HP16c. It is possible on the newest versions of the HP15c or the HP12c too (NOT Platinum). More details to come in following weeks!


There will be another option for HP15c cover too.

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More about: hp15c, hp16c
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Still more tests for overlays!

This HP16c overlay version has a little blurred yellow print - the jet seems to be too far from the surface. We'll receive it in a few days to try it mechanically - how it works. It can be used in any new Voyager calculator with the suitable firmware (HP12c -attention, NOT Platinum-, or HP15c CE)


















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More about: HP15c CE, hp16c
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More voyager overlay HP16c pictures - tests

Here is another picture fo the tests we are doing with overlays. difficult to get the process to get the colors right! Also the blue labels are still not well centered - next tests tomorrow! At least the keyboard works well and adheres well too: you need to shake hard the calculator to get it out. It will work well on that count!


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More about: HP15c CE, hp16c
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More comments on the new HP12c

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.


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More about: HP12c, hp15c, hp16c
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Reprogramming current models

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:



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More about: HP12c, hp15c, hp16c
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The HP16c Emulator (I)

There are three modules coming our way, with the latest modules as explained in the previous blog installment.

All of them have been loaded this week by Systemyde, so the owner will enjoy the very latest modules.

The one I am looking forward to is the HP16c Emulator module. I am not doing assembler, but once I did, so I was used to move figures from decimal to HEX and even sometimes to binary. But to be true, at that time we were using 8 bit words and 16 bit registers and addresses, so you can guess that we’re in the very first eighties!

This new module includes support for words of up to 64 bit - which is 8 of the old bytes! Even the HP41c registers were 1 byte shorter!

Monte (Systemwide “factotum”) told me that he uses it already, and defied me to use myself.

You can see the manual here:

This module makes use of the Library#4 created also by Angel Martín

Another day we’ll discuss the functions of Library #4 !

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More about: HP41cl, hp16c
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HP16c compatibility module for HP41C-CL


16c3qAngel Martin has created a new and exciting module for the hp41c. It provides emulation for the hp16 “Computer Scientist” calculator. It is freely available, and you can burn it on one of the available systems for that (the Clonix family and others), or in your hp41CL if you happen to have the serial module. By the way, it will become part of any new HP41CL modules, since Systemyde is now programming it as a standard module in the system.

It makes use of the #4 library too, so you will have to include it in your hp41 memory in some way (in Systemyde’s HP41CL module, we usually enter it in page 4, by POKEing the alpha string “804040–8120”). Be aware that Angel has recently made some improvements on the #4 library, so you need to load it too, if you were using a previous version of it.

Enough about setting it up. What this emulation module does? Well, all kind of base conversions between binary, octal, decimal and hexadecimal numbers. It makes full use of the alphanumeric 24-character register in the hp41, and is able to manage up to 64-bit decimal numbers (equivalent to 8 bytes or 16 hexadecimal numbers). It is also able to perform all kind of operations with these odd-base numbers, including rotation, carry, sign change, logical operations like AND, OR, XOR, etc.

It is true that the utility of such machines has diminished in our current world of increasingly high level programming languages - Swift couldn’t be farther from assembler code. But there will be occasions when you will have to descend to what is in the processor register, more so when you’re dealing with hardware at low level - and then you need to be able to know in advance how the system would react.

In the next days I will try to get a handle to this wonderful new module. Angel said that there were several things that come in addition to the original feature set of th HP16c, and that we would be in for some surprises. Let’s see!!

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