The Problem Of Making A Good Metal-To-Glass Seal

June 16, 2026 by 2 Comments

If you’ve ever taken a close look at a vacuum tube, you’ll have seen the seals around the pins that keep everything air-tight while providing the the device’s electrical contacts. As [maurycyz] finds out, it’s not an easy process to get right.

The problem is one of both chemistry and thermal expansion, as while a good seal can be made between glass and red copper oxide, it remains very difficult indeed to stop the glass cracking on cooldown due to differing thermal expansion properties. We’re led through a variety of experiments including surface treatments and flattening the metal to a sheet, with varying pros and cons. The most successful seal on the page comes from very thin tungsten wire, though hardly the most practical conductor for a vacuum tube.

It’s a fascinating investigation for the casual reader, taking them into the properties of metal-glass bonds and the difficulties involved in making them. We have even more respect for the people who make their own tubes after reading it.

Smart Bulb WiFi Server Hosts “Banned” Literature

June 16, 2026 by No comments

Let’s stop for a moment and pause to consider the smart bulb. Imagine going back 20 years and telling yourself that people will be putting computers capable of acting as web servers into light bulbs just so they can control them from their telephone instead of hitting the switch. The whole thing seems crazy — but its great, because it enables hacks like this one where [RickOOOOOO] takes a commercially-available ESP32 smart bulb, and hacks it into a local file server and digital library for banned books.

The word “banned” gets bandied about a lot — but assured, there’s nothing getting served up by [RickOOOOOO]’s bulb that’s going to help somebody will ill-intent build an improvised explosive device.  No, at least as conceived here, it appears to be full of easily-available e-books that were pulled from school libraries in the USA, which may-or-may not meet your personal definition of ‘banned’. Whatever you want to call them, we appreciate the idea that a student could hypothetically replace one of the bulbs at school with a hacked version serving up that sort of content. a bulb in such a school with a bulb hacked to host that sort of content–in minecraft, naturally.

In any case, the hardest part of the hack was carving the ESP32C3 in the bulb out of the IoToreo bulb enough to access it. Unfortunately having done so, [Rick] wasn’t able to get an SDcard interface soldered on, so he’s stuck with just 4MB for books and webserver. That means only a few epubs can fit on the bulb, but it’s better than those books being unavailable.

Like the solarpunk message board we featured recently, which also ran on an ESP32, the bulb broadcasts a public network that uses a captive portal to take you to the web interface of the library. From there, users can browse books– including learning from where they were banned and why–and admins can access a password-protected control panel. One neat work-in-progress feature on the control panel is that the bulb can still be used as a smart bulb, so you can try and match the light to its surroundings. In Minecraft, because of course we would never encourage kids to change light bulbs. Perish the thought!

Speaking of Minecraft, you can run a server on a lightbulb, too. Or DOOM, because of course even the light bulbs run DOOM now. What a time to be alive!

An image of a miniature diorama of Snow White and the Seven Dwarves. On the left is a more detailed 1/6 scale model with a tall, dark haired Snow White and dwarves with red caps and tan tunics. The image on the right is of a much smaller and less detailed set of miniatures. The figures's proportions are a little more uncanny and feel like a low budget Disney rip-off.

How Did They Make View-Master Slides?

June 16, 2026 by 7 Comments

The basics of producing a stereophotograph of real life places were well-established by the time the View-Master arrived, but producing images of imaginary scenes was a bit more involved. [View Master Travels and Peter Dibble] took a look at how the fairy tale and media tie-in reels may have been made.

Staring with simple dioramas, View-Master eventually developed an entire team to work on fairy tales. One of the most influential members was sculptor [Florence Thomas]. She was instrumental in updating many of the original fairy tale reels from small scale miniatures to 1/6 scale dioramas for the scenes. Unfortunately, the department was eventually cut and all the original miniatures thrown away.

Before VCRs, View-Master was the primary way people could interact with their favorite TV shows and movies when they weren’t being broadcast. TV shows could be photographed while in production in Hollywood with a stereo camera giving great visual detail. Some cartoon and movie reels were less engaging, having been made from promotional images, giving more of a paper cutout appearance rather than “real” 3D. In either case, many of these visual techniques have been lost with little documentation on how they were achieved.

We previously covered [View Master Travels and Peter Dibble]’s History of the View-Master and how you can digitize the disks for posterity.

Continue reading “How Did They Make View-Master Slides?” →

Image of an elf projected by the laser scanner

2026 Frikkin Lasers Contest: Glow Engine Is Like An Open Air Slow Scan CRT

June 16, 2026 by 5 Comments

Slow-scan CRTs were never exactly common compared to their faster cousins, but given the popularity of Slow Scan TV (SSTV) amongst hams and NASA broadcasts, many of you are probably familiar with them. The slow scan rate of SSTV meant it required much less bandwidth, but in the early days you needed a CRT with a long-persistence phosphor to hold onto the image. [AJRussell]’s Glow Engine works much the same, with one key difference — instead of cathode rays, he’s using a frikkin laser beam.

In this case, the phosphor is Strontium Aluminate, the same stuff that gives most glow-in-the-dark toys and filament its kick. Energized by a 405 nm laser of questionable wattage, the phosphor will glow for several seconds, allowing the creation of an image. So while this is a laser projector, it works more like a CRT than most galvo projectors, which rely on Persistence of Vision to create an image. Here it’s persistence of fluorescence.

Continue reading “2026 Frikkin Lasers Contest: Glow Engine Is Like An Open Air Slow Scan CRT” →

8087's 4-bit adder block. (Credit: Ken Shirriff)

The Adder At The Heart Of Intel’s 8087 FPU

June 16, 2026 by 1 Comment

As simple as the concept of adding two numbers appears at first glance, doing it in the 1970s in Intel’s 8087 FPU with its 69-bit adder was still a tall order. This is namely the core feature that many features like tangents, cosines and exponentiation rely on, so it had to be basically perfect. In a recent die-level analysis of the 8087 [Ken Shirrif] dives into the structure, layout and functioning of this ‘beating heart’ of this piece of semiconductor history.

The Intel 8087 adder and associated registers. (Credit: Intel)
The Intel 8087 adder and associated registers. (Credit: Intel)

Although anyone can build a simple binary adder out of off-the-shelf parts including 74-series logic ICs, the problem is to make it fast so that the 69th bit doesn’t have to wait for e.g. a carry to trickle all the way through the preceding bits. The main way that this is solved is by breaking addition into 4-bit blocks, reducing the problem by a factor of four, along with an optimized Manchester carry-chain carry-lookahead implementation.

The main advantage of this variation of a carry-lookahead is that it reduces the number of required transistors, without sacrificing too much performance. Later on Intel would switch to the faster, but more transistor-intensive Kogge-Stone adder.

Implementing this entire adder with NMOS technology and wiring it all up to the rest of the die required a lot of ingenuity on the side of the Intel engineers, as as previously noted this adder is effectively always used in any operation at some stage. This necessitates many surrounding registers and in turn circuitry to manage these, with part of the complexity handled in microcode and part in silicon.

A Brief History Of Unix Commands On Windows: CoreUtils (Again)

June 16, 2026 by 9 Comments

If you use Windows today and type ls, cat, grep, or awk in a terminal, there is a good chance something useful will happen. That was not always true. For most of the history of personal computing, Unix/Linux and Windows lived on opposite sides of a cultural border. Unix people had pipes, small composable tools, shell scripts, make, sed, awk, grep, tar, and the idea that everything was a file. Windows people had drive letters, backslashes, COMMAND.COM or cmd.exe, and an API that did not care much about what POSIX thought.

Yet there has always been a demand for Unix tools on Windows. Some of it came from programmers who wanted the same build scripts everywhere. Some came from administrators who missed grep and awk. Some came from companies trying to port big Unix applications to NT without rewriting them all. The result is a long, strange history of Unix-on-Windows layers, toolkits, compromises, and almost-but-not-quite compatibility.

Easy?

The simplest version of the problem sounds trivial. How hard can cat be? Open a file, copy bytes to standard output, done. Writing ls is a little more work, but Windows has directory APIs. Common commands like cp, mv, rm, mkdir are not very mysterious. Even pipes are not foreign to Windows. A lot of the everyday Unix command set can be ported as ordinary Win32 console programs with some path handling and enough patience.

But not all of Unix or Linux translates cleanly to Windows. The big issue is fork(). On Unix, a process can clone itself. The child gets a copy of the parent’s address space, open file descriptors, environment, signal state, and so on. Modern kernels make this efficient with copy-on-write memory, but the programming model is old and deeply baked into Unix. Shells use it constantly. Servers use it. Build systems use it. Scripting languages assume it exists, or at least that the surrounding environment behaves as though it does.

Windows process creation is different. Windows has CreateProcess(), which starts a new program. That is a perfectly reasonable model, but it is not fork() (more like fork()+exec()). If you are just launching notepad.exe, no problem. If you are trying to implement a POSIX shell that forks, redirects file descriptors, adjusts the environment, and then starts another program, the mismatch is extreme and you’ll have to do some strange things to fake things out.

One of the early commercial answers was the MKS Toolkit, originally from Mortice Kern Systems. MKS gave Windows users a pile of familiar commands, shells, and development tools. It was not just ls and friends; it included things like ksh, vi, grep, find, awk, make, and many of the utilities needed to move scripts and build procedures between Unix and Windows. The current PTC MKS documentation still describes it in exactly that spirit: Unix shells and hundreds of commands for interoperability with Windows.

MKS was attractive because it treated Windows as Windows. You were not necessarily pretending your machine was a Unix workstation. You were getting a Unix-flavored toolbox that could operate in a Windows environment. For many people, that was enough. You could write scripts, process text, drive builds, and avoid learning three different syntaxes for the same job.

Continue reading “A Brief History Of Unix Commands On Windows: CoreUtils (Again)” →

Honda Civics And Installing Software With Android Test Keys

June 16, 2026 by 19 Comments

As more and more of the ‘smart’ infotainment systems in cars begin to age out of support, it becomes increasingly more relevant to figure out how to do something with that lump of computer-and-display sitting prominently in the dashboard.

Here [Eric McDonald]’s reverse-engineering of the 2012-era Android-based infotainment system in a 2021 Honda Civic is an interesting case study, with recently the discovery made that the head unit of these infotainment systems can be updated via USB by using standard Android Open Source Project (AOSP) test keys as these were left on the file system.

This is a nice update to his initial reverse-engineering back in the innocent days of 2023, when such a facepalm-worthy exploit seemed unimaginable, but then the ‘s’ in ‘infotainment’ has always stood for ‘security’. In this exploit that [Eric] calls the EvilValet attack, it means that anyone with physical access to the USB port inside the car can theoretically run arbitrary code signed with these test keys, as documented in the GitHub project.

So far this rather foolish security issue has only been confirmed on [Eric]’s 2021 Honda Civic, but considering how those – often third-party – infotainment systems tend to get reused and recycled across generations and car variants, it’s quite possible that more Android-based infotainment systems have this vulnerability.

This exploit is obviously a double-edged sword, as on one hand it’s great that an owner of one of these cars can now basically do whatever they want with said infotainment system, but on the other hand it means that anyone who slides into your car with a USB stick can do the same.