Apollo Guidance Computer Gets The Rust Treatment

January 29, 2022 by Tom Nardi 8 Comments

Seems like all the cool kids are rewriting legacy C programs in Rust these days, so we suppose it was only a matter of time before somebody decided to combine the memory-safe language with some of the most historically significant software ever written by way of a new Apollo Guidance Computer (AGC) emulator. Written by [Felipe], the Apache/MIT licensed emulator can run either ROM files made from the computer’s original rope core memory, or your own code written in AGC4 assembly language.

It’s worth noting that the emulator, called ragc, needs a bit of help before it can deliver that authentic Moon landing experience. Specifically, the code only emulates the AGC itself and stops short of recreating the iconic display and keyboard (DSKY) module. To interact with the programs running on the virtual AGC you’ll need to also install yaDSKY2, an open source project that graphically recreates the panel Apollo astronauts actually used to enter commands and get data from the computer.

Of course, the next step would be to hack in support for talking to one of the physical recreations of the DSKY that have graced these pages over the years. Given the limitations of the AGC, we’d stop short of calling such an arrangement useful, but it would certainly make for a great conversation starter at the hackerspace.

Thanks for the tip, [CJ].

Blast Chips With This BBQ Lighter Fault Injection Tool

January 29, 2022 by Dan Maloney 16 Comments

Looking to get into fault injection for your reverse engineering projects, but don’t have the cash to lay out for the necessary hardware? Fear not, for the tools to glitch a chip may be as close as the nearest barbecue grill.

If you don’t know what chip glitching is, perhaps a primer is in order. Glitching, more formally known as electromagnetic fault injection (EMFI), or simply fault injection, is a technique that uses a pulse of electromagnetic energy to induce a fault in a running microcontroller or microprocessor. If the pulse occurs at just the right time, it may force the processor to skip an instruction, leaving the system in a potentially exploitable state.

EMFI tools are commercially available — we even recently featured a kit to build your own — but [rqu]’s homebrew version is decidedly simpler and cheaper than just about anything else. It consists of a piezoelectric gas grill igniter, a little bit of enameled magnet wire, and half of a small toroidal ferrite core. The core fragment gets a few turns of wire, which then gets soldered to the terminals on the igniter. Pressing the button generates a high-voltage pulse, which gets turned into an electromagnetic pulse by the coil. There’s a video of the tool in use in the Twitter thread, showing it easily glitching a PIC running a simple loop program.

To be sure, a tool as simple as this won’t do the trick in every situation, but it’s a cheap way to start exploring the potential of fault injection.

Thanks to [Jonas] for the tip.

Code Wrong: Expand Your Mind

January 29, 2022 by Elliot Williams 24 Comments

The really nice thing about doing something the “wrong” way is that there’s just so much variety! If you’re doing something the right way, the fastest way, or the optimal way, well, there’s just one way. But if you’re going to do it wrong, you’ve got a lot more design room.

Case in point: esoteric programming languages. The variety is stunning. There are languages intended to be unreadable, or to sound like Shakespearean sonnets, or cooking recipes, or hair-rock ballads. Some of the earliest esoteric languages were just jokes: compilations of all of the hassles of “real” programming languages of the time, but yet made to function. Some represent instructions as a grid of colored pixels. Some represent the code in a fashion that’s tantamount to encryption, and the only way to program them is by brute forcing the code space. Others, including the notorious Brainf*ck are actually not half as bad as their rap — it’s a very direct implementation of a Turing machine.

So you have a set of languages that are designed to be maximally unlike each other, or traditional programming languages, and yet still be able to do the work of instructing a computer to do what you want. And if you squint your eyes just right, and look at as many of them all together as you can, what emerges out of this blobby intersection of oddball languages is the essence of computing. Each language tries to be as wrong as possible, so what they have in common can only be the unavoidable core of coding.

While it might be interesting to compare an contrast Java and C++, or Python, nearly every serious programming language has so much in common that it’s just not as instructive. They are all doing it mostly right, and that means that they’re mostly about the human factors. Yawn. To really figure out what’s fundamental to computing, you have to get it wrong.

3D Printer Showdown: $350 Consumer Vs $73,000 Pro Machine

January 29, 2022 by Al Williams 35 Comments

The quality of consumer-grade 3D printing has gone way up in recent years. Resin printers, in particular, can produce amazing results and they get less expensive every day. [Squidmar] took a miniature design and printed it (or had it printed) on some cheap resin printers and a 65,000 Euro DWS029. How much difference could there be? You can see for yourself in the video below.

We were surprised at the specs for the more expensive machine. It does use a solid-state laser, but for that cost, the build volume is relatively small — around 15 x 15 x 10 cm. There were actually five prints created on four printers. Three were on what we think of as normal printers, one was on the 65,000 Euro machine, and the fifth print was on a 10,000 Euro printer that didn’t look much different from the less expensive ones.

Of course, there is more to the process than just the printer. The resin you use also impacts the final object. The printers tested included a Phrozen 4K Mini, a Phrozen 8K Mini, a Solos Pro, and the DWS 029D. The exact resins or materials used was hard to tell in each case, so that may have something to do with the comparisons, too.

Do you get what you pay for? Hard to say. The 8K and Solos were neck-and-neck with some features better on one printer and some better on the other. The DWS029D did perform better, but was it really worth the increase in price? Guess it depends on your sensitivity. The 8K printer did a very credible job for a fraction of the cost. Of course, some of that could have been a result of the materials used, too, but it does seem likely that a very expensive dental printer ought to do better than a hobby-grade machine. But it doesn’t seem to do much better.

The DWS printer uses a laser, while most hobby printers use UV light with an LCD mask. We’ve seen low-end resin printers on closeout for around $100 and you can get something pretty nice in the $200 neighborhood. In between these two extremes are printers that use Digital Light Processing (DLP).

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Radio Control Joby Aircraft Uses Six Tiltrotors To Fly

January 29, 2022 by Lewin Day 3 Comments

eVTOL (Electric Vertical Take-off and Landing) craft are some of the more exciting air vehicles being developed lately. They aim to combine the maneuverability and landing benefits of helicopters with the environmental benefits of electric drive, and are often touted as the only way air taxis could ever be practical. The aircraft from Joby Aviation are some of the most advanced in this space, and [Peter Ryseck] set about building a radio-controlled model that flies in the same way.

The design is inspired by the Joby eVTOL test vehicle.

The result is mighty complex, with six tilt rotors controlled via servos for the utmost in maneuverability. These allow the vehicle to take off vertically, while allowing the rotors to tilt horizontally for better efficiency in forward flight, as seen on the Bell-Boeing V-22 Osprey.

The build uses a 3D-printed chassis which made implementing all the tilt rotor mounts and mechanisms as straightforward as possible. A Teensy flight controller is responsible for controlling the craft, running the dRehmFlight VTOL firmware. The assembled craft only weighs 320 grams including battery; an impressive achievement given the extra motors and servos used relative to a regular quadcopter build.

With some tuning, hovering flight proved relatively easy to achieve. The inner four motors are used like a traditional quadcopter in this mode, constantly varying RPM to keep the craft stable. The outer two motors are then pivoted as needed for additional control authority.

In forward flight, pitch is controlled by adjusting the angle of the central four motors. Roll is achieved by tilting the rotors on either side of the plane’s central axis, and yaw control is provided by differential thrust. In the transitional period between modes, simple interpolation is used between both modes until transition is complete.

Outdoor flight testing showed the vehicle is readily capable of graceful forward flight much like a conventional fixed wing plane. In the hover mode, it just looks like any other multirotor. Overall, it’s a great demonstration of what it takes to build a successful tilt rotor craft.

We’ve seen tilt rotor UAVs before, and they’re as cool as they are complicated to build. Video after the break.

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The Air Multiplier Fan Principle, Applied To A Jet Engine

January 28, 2022 by Jenny List 26 Comments

Many readers will be familiar with the Dyson Air Multiplier, an ingenious bladeless fan design in which a compressor pushes jets of air from the inside edge of a large ring. This fast-moving air draws the surrounding air through the ring, giving the effect of a large conventional fan without any visible moving parts and in a small package. It’s left to [Integza] to take this idea and see it as the compressor for a jet engine, and though the prototype you see in the video below is fragile and prone to melting, it shows some promise.

His design copies the layout of a Dyson with the compressor underneath the ring, with a gas injector and igniter immediately above it. The burning gas-air mixture passes through the jets and draws the extra air through the ring, eventually forming a roaring jet engine flame exhaust behind it. Unfortunately the choice of 3D print for the prototype leads to very short run times before melting, but it’s possible to see it working during that brief window. Future work will involve a non-combustible construction, but his early efforts were unsatisfactory.

It’s clear that he hasn’t created the equivalent of a conventional turbojet. Since it appears that its operation happens when the flame has passed into the center of the ring, it has more in common with a ramjet that gains its required air velocity with the help of extra energy from an external compressor. Whether he’s created an interesting toy or a useful idea remains to be answered, but it’s certainly an entertaining video to watch.

Meanwhile, this isn’t the first project we’ve seen inspired by the Air Multiplier.

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Acoustic Switching Transistors: A New Kind Of Electronics?

January 28, 2022 by Al Williams 7 Comments

Have you ever heard of topological insulators? These are exotic materials where electricity flows only on the surface with very little loss. Now, according to IEEE Spectrum, scientists at Harvard have used the same concept to create a transistor for sound waves and it may be a new branch of electronics. The actual paper is available if you want some light reading.

Apparently, topological insulators protect electrons moving along their surfaces and edges, something that won the 2016 Nobel Prize in Physics. Photons can also be protected topologically so they move with very little loss across the materials. Making electrons flow in this manner is an attractive proposition, but there are challenges, especially when creating a device that can switch the flow of electrons on and off as you might with a transistor in and out of saturation. Sound waves, however, are much easier to work with.

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