Your Home Mainframe

We miss the days when computers looked like computers. You know, blinking lights, rows of switches, and cryptic displays. [Phil Tipping] must miss those days too since he built PlasMa, a “mini-mainframe simulator.”

The device would look at home on the set of any old science fiction movie. Externally, it has 540 LEDs, 100 switches, and a number of other I/O devices, including a keypad and an LCD screen. Internally, it can support three different instruction sets. Everything is run by an ATmega2560, and it has simulated paper tape, magnetic tape, and disks (all via SD cards). The magnetic tapes also have LED simulated reels to show the tape position and other status information (the round displays just above the LCD display).

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Moving Iron-Coated Polymer Particles Uphill Using External Magnetic Field

Microscopy of PMMA ferromagnetic Janus particle as used in the study (Credit: Wilson-Whitford et al., 2023)
Microscopy of PMMA ferromagnetic Janus particle as used in the study (Credit: Wilson-Whitford et al., 2023)

Granular media such as sand have a range of interesting properties that make it extremely useful, but they still will obey gravity and make their way downhill. That is, until you coat such particles with a ferromagnetic material like iron, make them spin using an external magnetic field and watch them make their way against gravity. This recent study by researchers has an accompanying video (also embedded below) that is probably best watched first before reading the study by Samuel R. Wilson-Whitford and colleagues in Nature Communications.

In the supplemental material the experimental setup is shown (see top image), which is designed to make the individual iron-coated polymer particles rotate. The particles are called Janus particles because only one hemisphere is coated using physical vapor deposition, leaving the other as uncovered PMMA (polymethyl methacrylate).

While one might expect that the rotating magnetic field would just make these particles spin in place, instead the researchers observed them forming temporary chains of particles, which were able to gradually churn their way upwards. Not only did this motion look like the inverse of granular media flowing downhill, the researchers also made a staircase obstacle that the Janus particles managed to traverse. Although no immediate practical application is apparent, these so-called ‘microrollers’ display an interesting method of locomotion in what’d otherwise be rather passive granular media.

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Making The Case For Wooden Wind Turbines With Swedish Modvion

Inside shot of the Modvion wooden wind turbine tower.
Inside shot of the Modvion wooden wind turbine tower.

Modern-day wind turbines are constructed using mostly concrete and steel, topped by the fiberglass composite blades mounted to the nacelle that houses the gearbox and generator, along with much of the control systems. With the ever increasing sizes of these turbines transporting the components to the installation location is a harrowing task, something which Swedish company Modvion claims to improve upon with its wooden tower elements that come mostly packaged flat, for on-site assembly. The BBC recently took a look at the first of these partially wooden wind turbine towers. At 105 meters tall, it features a standard V90-2.0MW turbine and blades.

Rather than using concrete slabs at the base with steel tower segments on top, or a fully steel tower like with most wind turbines, Modvion uses segments of layered wood which it calls ‘the module‘. These are assembled out of 144 layers of 3 mm thick spruce, with ring segments assembled on-site. This means that multiple of these modules can be stacked onto a standard truck with no concerns that come with oversized transports. According to Modvion these wooden towers should last about the same number of years as their steel counterparts. Continue reading “Making The Case For Wooden Wind Turbines With Swedish Modvion”

Copper Coating 3D Prints

We would all like to 3D print in metal, but for now, the equipment to do that is out of reach for most of us. Instead of dealing with powder printers or metal-bearing polymers, [Robert] has a simple solution. Using a process known as mechanical plating or peen plating, he deposits a layer of copper on a PLA print. The results look good, as you can see in the video below.

This isn’t electroplating, although the result is similar. With electroplating, you have to make the 3D part conductive. You also have to deal with wet chemistry and fumes. This process uses a rock tumbler, copper powder, and small ball bearings.

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Raspberry Pi Does Its Best Retro PC Impression

The Raspberry Pi is a popular choice if you’re looking to put together a simple emulation box — it’s relatively cheap, small enough to tuck into pretty much any entertainment center, and benefits from a large and vibrant development community. You can even get enclosures that will dress the Linux single-board computer up like a miniature version of your favorite retro console. But what about the old school PC gamers who want to relive their glory days in a palm-sized package?

Well, if you’ve got a 3D printer, [fantasticmrdavid] might have just the solution for you. This second iteration of his printable Raspberry Pi enclosure is designed to look like the 286 desktop that he had in his youth, complete with a functional “floppy drive” in the front that takes an SD card. With a 3.5 inch MPI3508 LCD up in the “monitor” and a copy of DOSBox on the SD card, you’re well on your way to booting up a copy of Windows 3.11 or building some contraptions in The Incredible Machine.

While the external aesthetics of the design are impeccable, we appreciate that [fantasticmrdavid] didn’t skimp on the internals. There’s mount points for dual 25 mm fans to keep the more powerful variants of the Raspberry Pi cool, and a speaker expansion board that plugs into the GPIO header to provide era-appropriate bloops and bleeps. The tiny details here really shine, like the fact that the face plates for the dual drives are designed as separate pieces so they can be printed in a different color than the main case.

If you’re not interested in the classics, don’t worry. We’ve seen the Raspberry Pi stand in foraa modern gaming PC, complete with the RGB LEDs you’d expect in a contemporary rig.

Linux Fu: Preprocessing Beyond Code

If you glanced at the title and thought, “I don’t care — I don’t write C code,” then hang on a minute. While it is true that C has a preprocessor and you can notoriously do strange and — depending on your point of view — horrible or wonderful things with it, there are actually other options and you don’t have to use any of them with a C program. You can actually use the C preprocessor with almost any kind of text file. And it’s not the only preprocessor you can abuse this way. For example, the m4 preprocessor is wildly complex, vastly underused, and can handle C source code or anything else you care to send to it.


I’ll define a preprocessor as a program that transforms its input file into an output file, reacting to commands that are probably embedded in the file itself. Most often, that output is then sent to some other program to do the “real” work. That covers cpp, the C preprocessor. It also covers things like sed. Honestly, you can easily create custom preprocessors using C, awk, Python, Perl, or any other programming language. There are many other standard programs that you could think of as preprocessors, for example, tr. However, one of the most powerful is made to preprocess complex input files called m4. For some reason — maybe because of its complexity — you don’t see much m4 in the wild.

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Unbricking Trains, Uncovering Shady Behavior

The first clue was that a number of locomotives started malfunctioning with exactly 1,000,000 km on the odometer. And when the company with the contract for servicing them couldn’t figure out why, they typed “Polish hackers” into a search engine, and found our heroes [Redford], [q3k], and [MrTick]. What follows is a story of industrial skullduggery, CAN bus sniffing, obscure reverse engineering, and heavy rolling stock, and a fantastically entertaining talk.

Cutting straight to the punchline, the manufacturer of the engines in question apparently also makes a lot of money on the service contracts, and included logic bombs in the firmware that would ensure that revenue stream while thwarting independent repair shops. They also included “cheat codes” that simply unlocked the conditions, which the Polish hackers uncovered as well. Perhaps the most blatant evidence of malfeasance, though, was that there were actually checks in some versions of the firmware that geofenced out the competitors’ repair shops.

We shouldn’t spoil too much more of the talk, and there’s active investigation and legal action pending, but the smoking guns are incredibly smoky. The theme of this year’s Chaos Communication Congress is “Unlocked”, and you couldn’t ask for a better demonstration of why it’s absolutely in the public interest that hackers gotta hack. Of course, [Daniel Lange] and [Felix Domke]’s reverse engineering of the VW Dieselgate ECU shenanigans, another all-time favorite, also comes to mind.