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It’s 1979 – What Exactly Did That ∫ Key Do?

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[Michel Jean] asked a question few others might: what exactly is going on under the hood of a classic HP scientific calculator when one presses the ∫ key ? A numerical integration, sure, but how exactly? There are a number of useful algorithms that could be firing up when the integral button is pressed, and like any curious hacker [Michel] decided to personally verify what was happening. [Michel] implemented different integration algorithms in C++ and experimentally compared them against HP calculator results. By setting up rigorous tests, [Michel] was able to conclude that the calculators definitely use Romberg-Kahan, developed by HP Mathematician William Kahan. Selected by HP in 1979 for use in their scientific calculators, the Romberg-Kahan algorithm was kept in service for nearly a decade. Was it because the algorithm was fast and efficient? Not really. The reason it was chosen over others was on account of its robustness. Some methods are ridiculously fast and tremendously e...
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Clear Resin Casting Replicates Old Acrylic for Selectric Repair

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IBM Selectric typewriters have a lot of unique parts that can be tricky to source, but one we didn’t think of was the clear acrylic(?) dust covers, that are apparently very hard to find in good shape. [Eric Strebel] has a few Selectrics that all have issues with these parts. While you could come close to recreating this piece with acrylic sheeting carefully bent to match the original shape, [Eric] has a different hammer to try in a new video: replicating it with a resin casting. He uses de-gassed tin-cure silicone to create a mold for the original, with a bit of 3D printed PLA and foam board to hold the silicone to create the mold. That’s done in two steps to create a two-part mold, which is separated and cleaned before the resin goes in. The original part is actually a smoky plastic, rather than fully clear, but [Eric] is able to match it perfectly using a colourant in his clear epoxy resin. The resin is put into the mold with a simple gravity pour, though he does have a vibrator on...
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There Are No LEDs Around the Face of This Clock

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This unusual clock by [Moritz v. Sivers] looks like a holographic dial surrounded by an LED ring, but that turns out to not be the case. What appears to be a ring of LEDs is in fact a second hologram. There are LEDs but they are tucked out of the way, and not directly visible. The result is a very unusual clock that really isn’t what it appears to be. The face of the clock is a reflection hologram of a numbered spiral that serves as a dial. A single LED – the only one visibly mounted – illuminates this hologram from the front in order to produce the sort of holographic image most of us are familiar with, creating a sense of depth. The lights around the circumference are another matter. What looks like a ring of LEDs serving as clock hands is actually a transmission hologram made of sixty separate exposures. By illuminating this hologram at just the right angle with LEDs (which are mounted behind the visible area), it is possible to selectively address each of those sixty exposures...
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Turning a GDB Coredump Debug Session Into a Murder Mystery

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Debugging an application crash can oftentimes feel like you’re an intrepid detective in a grimy noir detective story, tasked with figuring out the sordid details behind an ugly crime. Slogging through scarce clues and vapid hints, you find yourself down in the dumps, contemplating the deeper meaning of life and  the true nature of man, before hitting that eureka moment and cracking the case. One might say that this makes for a good game idea, and [Jonathan] would agree with that notion, thus creating the Fatal Core Dump game . Details can be found in the (spoiler-rich) blog post on how the game was conceived and implemented. The premise of the game is that of an inexplicable airlock failure on an asteroid mining station, with you being the engineer tasked to figure out whether it was ‘just a glitch’ or that something more sinister was afoot. Although an RPG-style game was also considered, ultimately that proved to be a massive challenge with RPG Maker, resulting in this more bar...
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The Sweetest Programming Language: MNM

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Admit it. If you haven’t created your own little programming language, you’ve probably at least thought about it. [Muffed] decided to create a unique — and sweet — programming language that uses M&M (or, at least, M&M-like) candies as the building block of programs . If this sounds strange, it is because, honestly, it is. It all started when a packet of GEMS (the Cadbury’s version of M&Ms)  spilled and randomly fell in the shape of an arrow. There are only six symbols corresponding to the colors in a package. You create your program by arranging the candies and creating a digital image of the result. In practice, you’ll probably use ASCII text to represent your candy layout and let the compiler render the image for you. The main way of encoding things is by the number of colored candy pixels in a row. So three blue morsels in an opcode, while four is a different opcode. Red candies encode integer literals with one candy being zero, two being one, and so on. Blue indi...
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Building a Class 100 Semiconductor Cleanroom Inside a Shed

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Just your typical backyard cleanroom shed. (Credit: Dr. Semiconductor, YouTube) Most people see that garden shed as little more than a place to store some gardening tools in, but if you’re like [Dr. Semiconductor], then what you see is a potential cleanroom for semiconductor manufacturing . As ridiculous as this may sound, the basic steps behind the different levels of cleanrooms work just as well for a multi-million dollar fab as they do for for a basic shed. Key to everything is HEPA filtration along with positive pressure, to constantly push clean air into the cleanroom, while preventing dirty air from flowing in. The shed was also split into two sections, the first room once you enter it being the the gowning room. This is where you change into cleanroom gear before you transition into the cleanroom. In addition to the flame-resistant drywalls, a water-based epoxy coating was applied to the insides of the cleanroom walls to make it smooth and free of debris. The HEPA filtrat...
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Real-Time ISS Tracker Shows Off the Goods

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What hardware hacker doesn’t have a soft spot for transparent cases? While they may have fallen out of mainstream favor, they have an undeniable appeal to anyone with an interest in electronic or mechanical devices. Which is why the Orbigator built by [wyojustin] stands out among similar desktop orbital trackers we’ve seen. Conceptually, it’s very similar to the International Space Station tracking lamp that [Will Dana] built in 2025 . In fact, [wyojustin] cites it specifically as one of the inspirations for this project. But unlike that build, which saw a small model of the ISS moving across the surface of the globe, a transparent globe is rotated around the internal mechanism. This not only looks gorgeous, but solves a key problem in [Will]’s design — that is, there’s no trailing servo wiring that needs to be kept track of. For anyone who wants an Orbigator of their own, [wyojustin] has done a fantastic job of documenting the hardware and software aspects of the build, and all th...
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