The Shockley 4-Layer Diode In 2026

March 14, 2026 by 5 Comments

The physicist William Shockley is perhaps today best known for three things: his role in the invention of the transistor, his calamitous management of Shockley Semiconductor which led to a mass defection of employees and precipitated the birth of the Silicon Valley we know, and his later descent into promoting eugenics. This was not the sum of his work though, and [David Prutchi] has been experimenting with a now-mostly-forgotten device that bears the Shockley name (PDF), after finding one used in an early heart pacemaker circuit.  His findings are both comprehensive and fascinating.

The Shockley diode, or 4-layer diode as it later became known, is as its name suggests a two terminal device with a 4-layer NPNP structure. It can be modeled as a pair of complementary transistors in parallel with a reverse biased diode, and the avalanche breakdown characteristics of that diode when a particular voltage is applied to it provide the impetus to turn on the two transistors. This makes it a voltage controlled switch, that activates when the voltage across it reaches that value.

The PDF linked above goes into the Shockley diode applications, and in them we find a range of relaxation oscillators, switches, and logic circuits. The oscillators in particular could be made with the barest minimum of components, important in a time when each semiconductor device could be very expensive. It may have faded into obscurity as it was superseded by more versatile 4-layer devices such as the PUJT or silicon-controlled switch and then integrated circuits, but he makes the point that its thyristor cousin is still very much with us.

This appears to be the first time we’ve featured a 4-layer diode, but we’ve certainly covered the genesis of the transistor in the past.

Porting MS-DOS 2.0 To The Apple IIe

March 13, 2026 by 2 Comments

Although the Apple II range of computers were based around the 6502 processor, they could still run x86 software using expansion cards that were effectively self-contained computers. This way an Apple IIe owner, for example, could install an Intel 8088-based AD8088 co-processor card by ALF Products and run CP/M-86 as well as MS-DOS. Unfortunately, as [Seth Kushniryk] discovered while digging into this MS-DOS option, there don’t seem to be any remaining copies of the accompanying MS-DOS 2.0 software.

The obvious response to this is of course to try and port it once again, which [Seth] did. So far he got it to boot, though it’s not quite ready for prime-time yet. Although the AD8088 card is fairly self-contained, it still has to talk with the Apple IIe system, which poses some challenges. To help with the porting he’s using the MS-DOS 2.0 OEM Adaptation Kit that was released along with the sources a while back.

The Apple II has to first load the basic MS-DOS files into the 8088’s RAM before handing over control, which works now along with the basic functionality. Before [Seth] releases the port to the public he still wants to fix a number of issues, in particular the clock. ProDOS on the Apple IIe encodes the year differently than MS-DOS, so that the latter’s clock is off by a few years, and the console driver is still not quite as robust as [Seth] would like it to be.

Beyond this there is also working with the other cards in the Apple II2 system, including the Super Serial Card, and working with the ProDOS filesystem.

OS/2 Never Went Away. Its Successor Has Received An Update

March 13, 2026 by 40 Comments

ArcaOS is an operating system you might not have heard of, but you will recognize it when we tell you that it’s the direct descendant of IBM’s OS/2. It’s just received a major update, and delivers this persuasive argument for its uptake:

“How about a commercial operating system which doesn’t spy on you, does not report your online activity to anyone, and gives you complete freedom to choose the applications you want to use, however you want to use them?”

We’re guessing that a higher-than-average number of Hackaday readers use open-source operating systems, but in a world in which the commercial OS everyone loves to hate is ever more turning the Play button into the Pay button, we have to admit that’s attractive if you pay for your software.

This update, version 5.1.2, brings support for the very latest UEFI systems to the table, keeping the platform alive in a manner we’d never have guessed would happen back in the 1990s. It’s true it’s a 32-bit system rather than 64-bit, and you’d be unlikely to buy it for your high-end gaming machine, but we remember OS/2 Warp back in the day as being very nice indeed and particularly stable. We’re interested enough to have put in a cheeky request for a review ISO, so should that come off we’d love to give it the Jenny’s Daily Drivers treatment.

ArcaOS has been mentioned here before. Do any of our readers encounter it in your daily lives? We’d love to hear in the comments.

Open Source Radar Has Up To 20 KM Range

March 12, 2026 by 37 Comments

Phased-array radars are great for all sorts of things, whether you’re doing advanced radio research or piloting a fifth-generation combat aircraft. They’re also typically very expensive. [Nawfal] hopes to make the technology more affordable with an open-source radar design of their own.

The design is called the AERIS-10, and is available in two versions. Operating at 10.5 GHz, it can be built to operate at ranges between 3 or 20 kilometers depending on the desired spec. The former uses an 8 x 16 patch antenna array, while the latter extends this to a 32 x 16 array. Either way, each design is capable of fully-electronic beam steering in azimuth and can be hacked to enable elevation too—one of the most attractive features of phased array radars. The hardware is based around an STM32 microcontroller, an FPGA, and a bunch of specialist clock generators, frequency synthesizers, phase shifters, and ADCs to do all the heavy lifting involved in radar.

Radar is something you probably don’t spend a lot of time thinking about unless you’re involved in maritime, air defence, or weather fields. All of which seem to be very much in the news lately! Still, we feature a good few projects on the topic around these parts. If you’ve got your own radar hacks brewing up in the lab, don’t hesitate to let us know. 

Mini Multi-Arcade Game Cabinets With An ESP32 And Galagino

March 11, 2026 by 7 Comments

Most people love arcade games, but putting a full-sized arcade cabinet in the living room can lead to certain unpleasant complications. Ergo the market for fun-sized cabinets has exploded alongside the availability of cheap SBCs and MCUs that can run classical arcade titles. Microcontrollers like the ESP32 with its dual 240 MHz cores can run circles around the CPU grunt of 1980s arcade hardware. Cue [Till Harbaum]’s Galagino ESP32-based arcade emulator project, that recently saw some community versions and cabinet takes.

There was a port to the PlatformIO framework by [speckhoiler] which also added a few more arcade titles and repurposed the enclosure of an off-the-shelf ‘My Arcade’ by stuffing in an ESP32-based ‘Cheap Yellow Display‘ (CYD) board instead. These boards include the ESP32 module, a touch display, micro SD card slot, sound output, and more; making it an interesting all-in-one solution for this purpose.

Most recently [Davide Gatti] and friends ported the Galagino software to the Arduino platform and added a 3D printed enclosure, though you will still need to source a stack of parts which are listed in the bill of materials. What you do get is a top display that displays the current game title in addition to the display of the usual CYD core, along with an enclosure that can be printed both in single- or multi-color.

There’s also a build video that [Davide Gatti] made, but it’s only in Italian, so a bit of a crash course in this language may be required for some finer details.

Continue reading “Mini Multi-Arcade Game Cabinets With An ESP32 And Galagino” →

The “Tin Blimp” Was A Neither Tin Nor A Blimp: The Detroit ZMC-2 Story

March 10, 2026 by 24 Comments
That fireball was LZ37. Nobody wanted to see repeats post-war.
Image: “The great exploit of lieutenant Warnefort 1916 England” by Gordon Crosby, public domain.

After all the crashing and burning of Imperial Germany’s Zeppelins in the later part of WWI – once the Brits managed to build interceptors that could hit their lofty altitude, and figured out the trick of using incendiary rounds to set off the hydrogen lift gas – there was a certain desire in airship circles to avoid fires. In the USA, that mostly took the form of replacing hydrogen with helium. Sure, it didn’t lift quite as well, but it also didn’t explode.

Still, supplies of helium were– and are– very much limited, and at least on a rigid Zeppelin, the hydrogen wasn’t even the most flammable part. As has become widely known, thanks in large part to the Mythbusters episode about the Hindenburg disaster, the doped cotton skin in use in those days was more flammable than some firestarters you can buy these days.

That’s a problem, because, as came up in the comments of our last airship article, rigid airships beat blimps largely on Rule of Cool. Who invented the blimp? Well, arguably it was Henri Griffard with his steam-driven balloon in 1857, but not many people have ever heard his name. Who invented the rigid airship? You know his name: Ferdinand Adolf Heinrich August Graf von Zeppelin. No relation. Probably. Well, admittedly most people don’t know the full name, but Count Zeppelin is still practically a household name over a century after his death. His invention was just that much cooler.

That unavoidable draw of coolness led to the Detroit Airship Company and their amazing tin blimp. The idea was the brainchild of a man named Ralph Upton, and is startling in its simplicity: why not take the all-metal, monocoque design that was just then being so successfully applied to heavier-than-air flight, and use it to build an airship? Continue reading “The “Tin Blimp” Was A Neither Tin Nor A Blimp: The Detroit ZMC-2 Story” →

GIF shows the impact window narrowing to exclude the moon

The Moon Is Safe, For Now: No Collision In 2032 After All

March 9, 2026 by 15 Comments

When Asteroid 2024 YR4 was first discovered, it created a bit of a kerfuffle when it was reported it had a couple-percent chance of hitting the Earth in 2032. At 60 meters (196 feet) across, this would have been in the “city killer” class that nobody really wants to see make landfall, so NASA and the ESA scrambled all assets to refine its trajectory in time to do something about it. Amongst those assets was the James Webb Space Telescope (JWST), which is now reporting it will miss both us and our moon.

Even with the JWST, asteroid 2024 YR4 only fills a few pixels.

We reported that JWST was being tapped for this task over a year ago, when the main concern was still if YR4 might hit Earth or not. An Earth impact was fairly quickly ruled out as the window narrowed to include only to Earth’s moon, and concern shifted to excitement. A city killer striking Earth is obviously bad news. The same thing happening to the Moon is a chance to do science — and 2032 would have been plenty of time to get assets in place to observe the impact.

Unfortunately for the impact-curious, JWST was able to narrow down the trajectory further — and we’ve now gone from up to a 4% chance of hitting Luna to a sure miss of 20,000 km or more.

As this game of cosmic billiards we call a solar system continues, it’s only a matter of time before Earth or her moon is struck by another object. Unless we can deflect it, that is — NASA and partnering agencies have been testing how to do that.