Calcuino Is An Arduino Calculator

June 28, 2020 by Al Williams 4 Comments

All by itself, a calculator based on an Arduino isn’t necessarily very novel. However, [Danko Bertović] of Volos Projects has a nice board that, of course, looks like a calculator. There are 16 keys and an LED display. But it seems to us the real value would be using this as a base for other projects.

As an inexpensive development board, it’s handy to have a simple processor with a keyboard and a display. There’s some extra I/O pins and the first example in the video below shows using the setup as a simple organ, for example. We’d love to see an option to replace the LED with an LCD and maybe even some different CPU options, as well.

The board is essentially an Arduino with a standard USB to serial chip and a MAX7219 display driver. Of course, you could breadboard up all of these things, but it wouldn’t be as neat looking. One unusual thing about the keyboard is that it is not multiplexed. Each button has a label that indicates what Arduino pin it connects with. So key 6 connects to pin 6 and pin A2 connects to the key marked =/A2.

With the availability of inexpensive PC boards, we’re seeing many nice designs out there that would be easy to repurpose for other things. For example, we thought this board would easily run the Kim Uno, with some modifications to the I/O routines. Might even be able to work out a clone of an even older computer to fit on the board.

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21st Century Cheating: WiFi In A Calculator

May 7, 2020 by Sven Gregori 48 Comments

Obviously, we would never endorse cheating on an exam, but sometimes a device is just too tempting to be left untouched. For [Neutrino], it was an old Casio calculator that happened to have a perfectly sized solar panel to fit a 128×32 OLED as replacement. But since the display won’t do much on its own, he decided to connect it to an ESP8266 and mount it all inside the calculator’s housing, turning it into a spy-worthy, internet-connected cheating device, including a stealthy user interface controlled by magnets instead of physical buttons. (Video, embedded below.)

Editor’s Update: Please read our follow-up coverage to the copyright claims made against this project. The video linked above and embedded below are unavailable due to these claims, despite widespread belief that this project does not violate copyright. For now, the original video is available via the Internet Archive.

To achieve the latter, [Neutrino] added two Hall effect sensors and a reed switch inside each end of the calculator. Placing a magnet — possibly hidden in a pen cap — near the reed switch will turn the display on, and placing another magnet near the Hall-effect sensors will navigate through the display’s interface, supporting two inputs with long, short, and multi-tap gestures each. To obtain information through WiFi, the ESP8266 connects to Firebase as backend, allowing to set up predefined content to fetch, as well as a possibility to communicate with your partner(s) in crime through a simple chat program.

As the main idea was to keep visible modifications to a minimum, one shortcoming is that charging the additional battery that powers the whole system would require an additional, external charging circuit. But [Neutrino] had a solution for that as well, and simply exposed two wires to the back, which could easily be mistaken for random solder splatters. And well, of course, requiring WiFi might also be tricky in some situations, so maybe you might want to consider a mobile network upgrade for yourself.

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Bus Sniffing Leads To New Display For Vintage Casio

March 8, 2020 by Tom Nardi 11 Comments

Despite his best efforts to repair the LCD on his Casio FX-702P, it soon became clear to [Andrew Menadue] that it was a dead-end. Rather than toss this relatively valuable device in the trash, he wondered if would be possible to replace the LCD with a more modern display. Knowing that reverse engineering the LCD panel itself would be quite a challenge, he decided instead to focus his efforts on decoding the communications between the calculator’s processor and display controller.

With his logic analyzer connected to the Casio’s four bit bus [Andrew] was able to capture a sequence of bytes during startup that looked promising, although it didn’t quite make sense at first. He had to reverse the order of each nibble, pair them back up into bytes, and then consult the FX-702P’s character map as the device doesn’t use ASCII. This allowed him to decode the message “READY”, and proved the concept was viable.

Of course a calculator with a logic analyzer permanently attached to it isn’t exactly ideal, so he started work on something a bit more compact. Armed with plenty of display controller data dumps, [Andrew] wrote some code for a STM32 “Blue Pill” ARM Cortex M3 microcontroller that would sniff and decode the data in near real-time. In the video after the break you can see there’s a slight delay between when he pushes a button and when the corresponding character comes up on the LCD below, but it’s certainly usable.

Unfortunately, the hardware he’s created for this hack is just slightly too large to fit inside the calculator proper. The new LCD is also nowhere near the size and shape that would be required to replace the original one. But none of that really matters. While [Andrew] says he could certainly make the electronics smaller, the goal was never to restore the calculator to like-new condition. Sometimes it’s more about the journey than the destination.

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A Calculator In 2020?

March 7, 2020 by Elliot Williams 91 Comments

This week, Al Williams wrote up an article on what might be the last scientific calculator. Back in the day, the fanciest of scientific calculators had not just sin, cos, and tan, but were also programmable so that you could code in frequently used formulae. And the calculator that he reviews is certainly powerful: with a screen, processor, and memory almost rivalling a mid-scale smartphone.

Wait a minute! “Almost”? I have a smartphone in my pocket right now. Why would I want something less powerful, when all that the calculator brings to the table is a bit of software? And that app can even be purchased for $20!

I’ll confess. I want a proper desktop calculator from time to time. But why? Sure, I can run calculations on the very computer that I’m using to type right now. And in terms of programming languages, the resources are far superior on my laptop. Unit conversions? Units, or the Interwebs. Heck, I can even type calculations directly into the Unix world’s default editor.

But there’s something nice about the single-purpose device. Maybe it’s the feel of the keys. Maybe it’s because it doesn’t require a context-switch on the computer. Maybe it’s irrational calculator nostalgia. Or maybe it’s an elegant tool from a more civilized age: the user experience is better because the tool is just simpler.

I like stand-alone devices that do their one thing right, and I almost always pick them over their more complex, if also more capable, counterparts when I only need that function. The fixed wrench over the adjustable wrench. The standalone audio recorder over my computer’s software. The simple bench power supply over the programmable. And, when I’m actually setting out to take good photos, a real camera instead of my cell phone’s. Purpose-built tools tend to work much better for their purpose than devices that try to do everything.

The days of the standalone calculator are nearly gone, though, so what am I going to do? I’m certainly not going to shell out megabucks for an overly-fancy calculator, nor am I going to be lured by nostalgia into picking up an antique at the ridiculous prices they fetch online. That leaves one option, and it’s both the Hackaday and the Jedi way. I’m going to have to build it myself. Where am I going to get a nice-feeling numeric keypad?

The Last Scientific Calculator?

March 2, 2020 by Al Williams 105 Comments

There was a time when being an engineering student meant you had a sword. Well, really it was a slide rule hanging from your belt, but it sounds cooler to call it a sword. The slide rule sword gave way to calculators hanging from your belt loop, and for many engineers that calculator was from HP. Today’s students are more likely to have a TI or Casio calculator, but HP is still in there with the HP Prime. It is hard to call it a calculator since the latest variant has a 528 MHz ARM Cortex A7, 256 MB of RAM, and 512 MB of ROM. But if you can’t justify a $150 calculator, there are some cheap and even free options out there to get the experience. To start with, HP has a free app that runs on Windows or Mac that works just like the calculator. Of course, that’s free as in no charge, not free as in open source. But still, it will run under Wine with no more than the usual amount of coaxing.

You might wonder why you need a calculator on your computer, and perhaps you don’t. However, the HP Prime isn’t just your 1980s vintage calculator. It also has an amazing number of applications including a complete symbolic math system based on xCAS/Giac. It is also programmable using a special HP language that is sort of like Basic or Pascal. Other applications include plotting, statistics, solvers, and even a spreadsheet that can hold up to 10,000 rows and 676 columns.

Portability

It is easy to think that HP provides the free PC software so you’ll go out and buy the real calculator, and that may be part of it. However, you can also get official apps for Android and iOS. They aren’t free, but they are relatively inexpensive. On iOS the cost right now is $25 and on Android it is $20. There are also “lite” versions that are free.

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Retrotechtacular: Mechanical Arithmetic For The Masses

December 18, 2019 by Jenny List 24 Comments

Last month we carried a piece looking at the development of the 8-bit home computer market through the lens of the British catalogue retailer Argos and their perennial catalogue of dreams. As an aside, we mentioned that the earliest edition from 1975 contained some of the last mechanical calculators on the market, alongside a few early electronic models. This month it’s worth returning to those devices, because though they are largely forgotten now, they were part of the scenery and clutter of a typical office for most of the century.

The Summa's internals, showing the register on the right and the type wheels on the left. — The Summa’s internals, showing the register on the right and the type wheels on the left.

Somewhere in storage I have one of the models featured in the catalogue, an Olivetti Summa Prima. I happened upon it in a dumpster as a teenager looking for broken TVs to scavenge for parts, cut down a pair of typewriter ribbon reels to fit it, and after playing with it for a while added it to my store of random tech ephemera. It’s a compact and stylish desktop unit from about 1970, on its front is a numerical keypad, top is a printer with a holder for a roll of receipt paper and a typewriter-style rubber roller, while on its side is a spring-loaded handle from which it derives its power. It can do simple addition and subtraction in the old British currency units, and operating it is a simple case of punching in a number, pulling the handle, and watching the result spool out on the paper tape. Its register appears to be a set of rotors advanced or retarded by the handle for either addition or subtraction, and its printing is achieved by a set of print bars sliding up to line the correct number with the inked ribbon. For me in 1987 with my LCD Casio Scientific it was an entertaining mechanical curiosity, but for its operators twenty years earlier it must have represented a significant time saving.

The history of mechanical calculators goes back over several hundred years to Blaise Pascal in the 17th century, and over that time they evolved through a series of inventions into surprisingly sophisticated machines that were capable of handling financial complications surprisingly quickly. The Summa was one of the last machines available in great numbers, and even as it was brought to market in the 1960s its manufacturer was also producing one of the first desktop-sized computers. Its price in that 1975 Argos catalogue is hardly cheap but around the same as an electronic equivalent, itself a minor miracle given how many parts it contains and how complex it must have been to manufacture.

We’ve put two Summa Prima videos below the break. T.the first is a contemporary advert for the machine, and the second is a modern introduction to the machine partially narrated by a Brazilian robot, so consider translated subtitles. In that second video you can see something of its internals as the bare mechanism is cranked over for the camera and some of the mechanical complexity of the device becomes very obvious. It might seem odd to pull a obsolete piece of office machinery from a dumpster and hang onto it for three decades, but I’m very glad indeed that a 1980s teenage me did so. You’re probably unlikely to stumble upon one in 2019, but should you do so it’s a device that’s very much worth adding to your collection.

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3D-Printer And CNC Make This Russian Calculator Bilingual

December 13, 2019 by Dan Maloney 11 Comments

Let’s be clear right up front: there are probably more obvious solutions to the problem of using a Russian calculator when you don’t speak Russian than printing new keys and engraving translated markings on them. But easy solutions are boring and generally considered beyond the scope of Hackaday articles, so let’s dive in.

They say that mathematics is the universal language, but that’s only true to an extent. Still, even with our ~~limited~~ non-existent Cyrillic skills, the Russian keyboard on this RPN calculator isn’t that hard to figure out. But as [Amen] points out, in the midst of fevered calculations, one prefers not to mentally translate Χ→П to STO or remember that В↑ is the Enter key. So he printed a set of replacements for the confusing keys from PLA. While pondering how to safely fixture such small parts for the later engraving step, [Amen] hit on a genius solution: move the print bed to the CNC router and fixture everything in one go. The resulting characters are large enough to be legible and deep enough to be filled with air-drying polymer clay for contrast. After sanding and polishing, the calculator looks like it came from the Министерство электронной промышленности that way.

Honestly, we’d love to get a look inside this calculator. The insides of Russian electronics can be fascinating, and we’ve even seen entire forums dedicated to decapping Russian parts. But we understand the desire to keep it intact.

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