Make Your Own 1970s Magnetic Stripe Cards

October 25, 2023 by Jenny List 8 Comments

We’re now all used to near-limitless storage on flash and other semiconductor technologies, but there was a time when persistent storage was considerably less easy to achieve. A 1970s programmable calculator from Sharp approached the problem with magnetic strips on special cards, and since [Menadue] has one with no cards, he set about making his own.

These cards are a little different to the credit-card-style cards we might expect, instead they’re a narrow strip with a magnetic stripe down their centre. The unusual feature can be found at the edge, where a row of perforations provide the equivalent of a clock line.

The newly manufactured cards have the clock slots machined along their edges, and then the magnetic part formed from self-adhesive magnetic strip. This last thing is a product we were not aware existed, and can think of plenty of possible applications.

The result as you can see in the video below the break are some cards with variable reliability. There’s a suggestion that white cards might work less well with the infrared light used in the clock detector, also a suspicion the low batteries make reading less easy, but still he’s able to retrieve a stored program. An extinct medium is revived.

Longtime readers will know we’ve spent time in calculator country before.

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Pocket Calculator Isn’t A Brain Or Magic

October 20, 2023 by Al Williams 18 Comments

If you predate the pocket calculator, you may remember slide rules. But slide rules take a a little skill to use. There was a market for other devices that were simpler or, in some cases, cheaper. One common one was the “magic brain” or Addiator which was a little metal box with some slots that could add numbers. However, using clever tricks it could also subtract and — in a fashion — multiply. [Our Own Devices] has a teardown of the device you can see in the video below. It is deceptively simple, and the description of how it works is at least as interesting as the peek inside.

We remember these on the market and, honestly, always thought they were simple tally mechanisms. It turns out they are both less and more than that. Internally, the device is a few serrated sheet metal strips in a plastic channel. The subtraction uses a complement addition similar to how you do binary subtraction using 2’s complement math. Multiplication is just repetitive addition, which is fine for simple problems.

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HP1973 Project Highlights Workings Of HP-45 Calculator

July 24, 2023 by Chris Lott 3 Comments

[Sarah K Marr] dabbles in retrocomputing and has a fascination with the Hewlett Packard HP-45 calculator, the second calculator in HP’s series introduced in 1973. Over a year ago, she wrote an HP-45 emulator for use on a terminal, dubbed HP45TERM. Not content with success, she upped the challenge and decided to build an even better emulator with a full-featured GUI written in Python. Oh, and she made it multi-platform as well. The result is the HP1973 project.

[Sarah] thought it would take just a few days, but it grew into a much bigger project, as often happens. We’re glad it did because the results are fantastic. The emulator gives you access not only to the calculator itself but can see everything under the hood. The emulator provides full ROM visibility, hardware registers, and standard debugging operations like single stepping. ROM images are available for the HP-45, the HP-35, and the HP-80. The GUI display is configurable, and there’s a plethora of help and information explaining the calculator’s internals. Pre-built binaries are available for MacOS, Windows, and Python source code (3.10.10+) for all operating systems (you’ll need to `pip install numpy` first). The emulation is faithful to the original calculator, and even the hidden timer function can be accessed.

Check this out if you’re into retro calculators. Our own Al Williams wrote about the history of the HP-35 back in 2018 if you want to learn more. Thanks to [J Peterson] for sending in the tip.

Hackaday Links: June 18, 2023

June 18, 2023 by Dan Maloney 19 Comments

Will it or won’t it? That’s the question much on the minds of astronomers, astrophysicists, and the astro-adjacent this week as Betelgeuse continued its pattern of mysterious behavior that might portend a supernova sometime soon. You’ll recall that the red giant star in the constellation Orion went through a “great dimming” event back in 2019, where its brightness dipped to 60% of its normal intensity. That was taken as a sign that perhaps the star was getting ready to explode — or rather, that the light from whatever happened to the star 548 years ago finally reached us — and was much anticipated by skywatchers, yours truly included. As it turned out, the dimming was likely caused by Betelgeuse belching forth an immense plume of dust, temporarily obscuring our view of its light. Disappointing.

Those who gave up on the hope of seeing a supernova might have done so too fast, though, because now, the star seems to be swinging the other way and brightening. It briefly became the brightest star in Orion, nearly outshining nearby Sirius, the brightest star in the sky. So what does all this on-again, off-again business mean? According to Dr. Becky, a new study — not yet peer-reviewed, so proceed with caution — suggests that the star could go supernova in the next few decades. The evidence for this is completely unrelated to the great dimming event, but by analyzing the star’s long history of variable brightness. The data suggest that Betelgeuse has entered the carbon fusion phase of its life, a period that only lasts on the scale of a hundred years for a star that size. So we could be in for the ultimate fireworks show, which would leave us with a star brighter than the full moon that’s visible even in daylight. And who doesn’t want to see something like that?

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Hackaday Links: May 28, 2023

May 28, 2023 by Dan Maloney 20 Comments

The Great Automotive AM Radio War of 2023 rages on, with the news this week that Ford has capitulated, at least for now. You’ll recall that the opening salvo came when the US automaker declared that AM radio was unusable in their EV offerings thanks to interference generated by the motor controller. Rather than fixing the root problem, Ford decided to delete the AM option from their EV infotainment systems, while letting their rolling EMI generators just keep blasting out interference for everyone to enjoy. Lawmakers began rattling their sabers in response, threatening legislation to include AM radio in every vehicle as a matter of public safety. Ford saw the writing on the wall and reversed course, saying that AM is back for at least the 2024 model year, and that vehicles already delivered without it will get a fix via software update.

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Probably The Most Over-Specified Calculator To Ever Be Manufactured

March 7, 2023 by Jenny List 38 Comments

It’s possible quite a few of our older readers will remember the period from the 1960s into the ’70s when an electronic calculator was the cutting edge of consumer-grade digital technology. By the 1980s though, they were old hat and could be bought for only a few dollars, a situation that remains to this day. But does that mean calculator development dead?

Perhaps not, as [Li Zexi] writes for CNX Software, when he reviews a simple non-scientific calculator that packs an Alwinner A50 tablet SoC and the Android operating system. As shipped they lack the Android launcher, so they aren’t designed to run much more than the calculator app. Of course that won’t stop somebody who knows their way around Google’s mobile operating system for very long — at the end of the review, there’s some shots of the gadget running Minecraft and playing streaming video.

These devices can be had for not a lot on the Chinese second-hand electronics market, and after an extensive teardown he comes to the conclusion that besides their novelty they’re an older specification so not really worth buying.

But it does beg the question as to why such a product was put into production when the same task could have been performed using very cheap microcontroller. Further, having done so they make it a non-scientific machine, not even bestowing it with anything that could possibly justify the hardware. Is there a use case he, and us, have missed? We’d love to know.

We cover a lot of calculator stories here at Hackaday. Sometimes they’re classic machines, but more often they’re modern takes on an old idea.

A Reverse Polish Calculator For Your Keychain

January 31, 2023 by Jenny List 24 Comments

As the smartphone has eaten ever more of the gatgets with which we once surrounded ourselves, it’s with some sadness that we note the calculator becoming a less common sight. It’s with pleasure then that we bring you [Nekopla]’s keychain calculator, not least because it’s a little more than a conventional model. This is a calculator which uses Reverse Polish Notation, or RPN.

A full write-up in Japanese (Google Translate link) carries an impressive level of detail about the project, but in short, it takes an Arduino Pro Micro, an array of keys, and an OLED display, and packages them on a couple of fiberglass prototyping boards in a sandwich between laser-cut Perspex front and rear panels.

The RPN notation is what makes it especially interesting,a system in which where you might be used to writing 2+2= to get 4, in RPN you would write 2 2 + . It allows the use of much simpler code with a stack-based architecture than that used in a conventional calculator. It’s a system that’s usually the preserve of some pretty exclusive machines, so it’s great to see on something with more of the toy about it.

If RPN interests you, then you might like to read our look at the subject, and even feast your eyes on the teardown of a vintage 1975 Sinclair RPN calculator.