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Calculator blog

Musings and comments about our common interest


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Buying 2 HP15c CE?

IMG_1046Why not? In my case it is easier than in others for obvious reasons. However, lately I had to do several conversions from Hexadecimal to Decimal - and while I can do them in the "Base" menu of the HP Prime, it is actually easier to use the HP16c to add, subtract and calculate.

However, every time I do it I need to reset the memory and programs of my HP15c. So far there are not that many - but I hate to rewrite them every time. So I took another HP15c, this time in HP16c mode, running with the DECbug patch and the HP16c overlay. I even have a different leather case for each. The HP16c is using the Bordeaux leather case - just to make sure that I reach for the right one in each case. Voilà!

At least one of our customers has done it too. You may read his comments in Makes full sense if you load your HP15c with lots of programs as we do!! 

[You can ask us to have it patched and tested for 25€ before shipping - please remember to order the Flashing Voyager article when ordering yours]

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Patching Voyager calculators

We offer a flashing service for calculators using the POGO connector. These include the HP12c, HP15c and HP10bII+. There are community patches available for the HP15c. This patch solves the DEC bug in the non-manufacturer-supported HP16c mode, from a solution devised by a well-known community member. The second picture shows a calculator without the bug. In a calculator with the bug, it would show 105 instead. You'd need to send the calculator back and we will patch it and send it back. 

IMG_4647_Mediano IMG_0956_en_tamano_grandeThe DEC bug is just a display bug that affects the HP16c mode: the values are still correct in the registers. If you do not have the overlay, you may as well forget about it because you will never experiece it: it does not affect any of the two HP15c modes. 

If you order the HP15c Computer Science edition, which includes the overlay, you can also order the patching together when you buy it. You will receive the calculator already patched, working perfectly. This serves as well to weed out the odd defective unit, since we have to test thoroughly the unit before shipping.

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DEC bug solved - testing a patch

An image is worth 1000 words: as you know, in the NOMAS HP16c this screen was not possible. When you keyed 111, you got 105 !! This was called the "DEC" bug. You could not complain: it was a gift and it was Not manufacturer supported feature. Now "someone" (we don't know if he wants his name mentioned) has created a patch that we are testing. As it only patches a couple of bytes in the HP16c ROM, it should not impact on 15 or 15.2 performance. We've been using it during 15 days with no issues whatsoever.


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Cable II

We have found finally a producer that has access to pogo pins at the same picth as the one in the HP calculators. It is a different pitch from the industry standard 2.54mm - which makes it difficult to find a replacement.

Now we are discussing the prices - prior to this, we did not even know with whom to discuss! Let's hope to strik an agreement and be able to have a product for Christmas.

Here are some pictures now drawn by the factory:



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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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New service - firmware installation

IMG_4647_MedianoNot too many people have a cable to reprogram HP calculators. The HP15 LE cable had the same connector, but it is NOT compatible. You need to make destructuve changes to the old cable to be able to use with the new HP calculators.

Well, we have one, so that we can reprogram these calculators. We are offering that service. Now the important thing is to have a new firmware!

We are testing a couple of possible firmwares that solve the main bug in the HP16c emulation. One of them is working well so far! We'd need to get the permissions, but this one is a strong candidate to replace the original firmware. Too early to decide, though.

We are also considering producing our own cable - industrially. But this will take longer...


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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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So far, the definitive video review of the new HP15c CE

Here is the definitive review of the HP15c CE calculator. BTW - the batteries are in parallel to provide 3v.

No association whatsoever with the poster of the video!


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New HP15c batch arrived!

We are shipping now all the pending orders of HP15c, since the boat units of HP15c have arrived yesterday!! Hectic days again.


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All first batch's shipping is over!!

The early orders for the HP15c Collector's Edition have all been shipped. From now on, it is business as usual - normal ordrs coming in and out.

705 orders have been fulfilled for a total of 937 calculators. Several people decided to take 2 or more calculators, profiteering from the discount for more than 5 and more than 10 units built into the price structure.

And in many cases the customers have already received them. We did not use the postal system, just courier companies, with typical delivery lapses of 2-3 days within Europe. 


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