Linux Fu: The Old School Terminal

August 23, 2023 by 40 Comments

Maybe you have a vintage old-school computer. Maybe you have a replica. Maybe you just want to run SIMH and relive the glory days of CP/M or VMS. The problem is, it looks kind of silly to have CP/M running in your beautiful X11 terminal window full of 3D animations, opacity effects, and special fonts. You could buy an old CRT monitor. That would be cool, too, because on a modern screen, you don’t get scan lines and all the crummy artifacts that go along with an electron beam and phosphor display device. Or you can grab retro-cool-term.

Star Trek on CP/M

Even if you don’t have an old computer, the program will work fine to simply run your shell for everyday use. Confound the youngsters when they see your terminal with scan lines and CRT jitter updating the latest packages.

What Is It?

If you want a shell in a GUI, you used to use xterm, although most people use something more modern. I use Konsole, but some like RXVT or whatever terminal your distro favors. Cool-retro-term is just a replacement for this. By default, it only opens a shell prompt.

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Improving A Kodak Film Digitizer

August 23, 2023 by 12 Comments

Despite the near-complete collapse of its ecosystem in the face of portable videocassette camcorders in the 1980s, somehow the 8 mm format, smallest of the movie films, has survived the decades. There’s a special aura around an 8 mm image which electronic recordings don’t replicate, plus for film makers there’s an attraction to working with real film. Unsurprisingly almost all of the devices used with 8 mm film have ceased to be manufactured, but a few items escaped the cut. It’s still possible to buy an 8 mm digitizer for example, and it’s one of these with a Kodak brand that [Mac84] has. Unsatisfied with its image quality, he’s set about tinkering with its firmware to give it some video adjustment possibilities and remove its artifact-prone artificial sharpening.

Helped by the device having a handy EEPROM from which to extract the code, he was able to recover the firmware intact. From here on he was in luck, because the digitizer’s Novatek CPU is shared with some dash cams and this had spawned a hacker scene. From there he was able to find the relevant area and adjust those settings, and after a few false starts, re-flash it to the device.

The results can be seen in the video below the break, and perhaps reveal much about what we expect from an image in the digital age. The sharpened images look good, until we see untampered versions which are closer to the original.

If you don’t have a Kodak scanner you can always build one yourself, and meanwhile like many people we are still wondering what happened to that new Super 8 camera they announced in 2018 but never released.

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Sharkskin Coating Reduces Airliner Fuel Use, Emissions

August 23, 2023 by 66 Comments

The aviation industry is always seeking advancements to improve efficiency and reduce carbon emissions. The former is due to the never-ending quest for profit, while the latter helps airlines maintain their social license to operate. Less cynically, more efficient technologies are better for the environment, too.

One of the latest innovations in this space is a new sharkskin-like film applied to airliners to help cut drag. Inspired by nature itself, it’s a surface treatment technology that mimics the unique characteristics of sharkskin to enhance aircraft efficiency. Even better, it’s already in commercial service! Continue reading “Sharkskin Coating Reduces Airliner Fuel Use, Emissions” →

Guitar Distortion With Diodes In Code, Not Hardware

August 23, 2023 by 14 Comments

Guitarists will do just about anything to get just the right sound out of their setup, including purposely introducing all manner of distortion into the signal. It seems counter-intuitive, but it works, at least when it’s done right. But what exactly is going on with the signal? And is there a way to simulate it? Of course there is, and all it takes is a little math and some Arduino code.

Now, there are a lot of different techniques for modifying the signal from an electric guitar, but perhaps the simplest is the humble diode clipping circuit. It just uses an op-amp with antiparallel diodes either in series in the feedback loop or shunting the output to ground. The diodes clip the tops and bottoms off of the sine waves, turning them into something closer to a square wave, adding those extra harmonics that really fatten the sound. It’s a simple hack that’s easy to implement in hardware, enough so that distortion pedals galore are commercially available.

In the video below, [Sebastian] explains that this distortion is also pretty easy to reproduce algorithmically. He breaks down the math behind this, which is actually pretty approachable — a step function with a linear part, a quadratic section, and a hard-clipping function. He also derives a second, natural exponent step function from the Schockley diode equation that is less computationally demanding. To implement these models, [Sebastian] chose an Arduino GIGA R1 WiFi, using an ADC to digitize the guitar signal and devoting a DAC to each of the two algorithms. Each distortion effect has its own charms; we prefer the harsher step function over the exponential algorithm, but different strokes.

Kudos to [Sebastian] for this easy-to-understand treatment of what could otherwise be a difficult subject to digest. We didn’t really expect that a guitar distortion pedal would lead down the rabbit hole to diode theory and digital signal processing, but we’re glad it did.

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Wooden Wide-Angle Wonder Wows World

August 23, 2023 by 9 Comments

An old-fashioned film camera can be an extremely simple device to make, in that as little as a cardboard box with a pin hole in it will suffice. But that simplicity at heart leaves endless scope for further work, and a home-made camera can be every bit as much a highly-engineered object of beauty as its commercial stablemate. A great example comes from [Aaron Cré], whose desire for something close to a Hasselblad XPan panoramic camera led him to build his own equivalent out of wood.

The video below the break shows in detail how the wooden case is crafted, and how a lens mount ring sawn from a lens adapter is mounted on the front of it. He’s skipped making all the tiresome parts of the camera associated with winding and film transport and instead taken them from a cheap plastic snapshot camera. The original aspect ratio is stretched by cutting the guts of the snapshot camera apart, and extended to make a 75 mm long negative which also exposes over the sprocket holes.

The final camera is carefully finished to the point at which it really looks the part as well as taking those striking wide-angle photographs. We’re not photography buffs enough to identify the lens and shutter combination he’s using, but we can’t help envying him the results. Fancy making your own 35 mm camera too? Here’s another, in case you need inspiration.

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SLR To DSLR Conversion Becomes Full Camera

August 22, 2023 by 8 Comments

At least as far as the inner workings are concerned, there’s not a whole lot of difference between an single-lens reflex (SLR) camera that uses film and a digital SLR (DSLR) camera that uses an electronic sensor except the method for capturing the image. So adding the digital image sensor to a formerly analog camera like this seemed like an interesting project for [Wenting Zhang]. But this camera ballooned a little further than that as he found himself instead building a complete, full-frame digital camera nearly from scratch.

The camera uses a full-frame design and even though the project originally began around the SLR mechanism, in the end [Wenting] decided not to keep this complex system in place. Instead, to keep the design simple and more accessible a mirrorless design is used with an electronic viewfinder system. It’s also passive M lens mount, meaning that plenty of manual lenses will be available for this camera without having to completely re-invent the wheel.

As far as the sensor goes, [Wenting] wanted something relatively user-friendly with datasheets available so he turned to industrial cameras to find something suitable, settling on a Kodak charge-coupled device (CCD) for the sensor paired with an i.MX processor. All of the electronics have publicly-available datasheets which is important for this open-source design. There’s a lot more work that went into this build than just picking parts and 3D printing a case, though, and we’d definitely recommend anyone interested to check out the video below for how this was all done. And, for those who want to go back to the beginnings of this project and take a different path, it’s definitely possible to convert an analog SLR to a digital one.

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LaForge Demystifies ESIM

August 22, 2023 by 8 Comments

This talk at Chaos Communications Camp 2023 is probably everything you want to know about eSIM technology, in just under an hour. And it’s surprisingly complicated. If you’ve never dug into SIMs before, you should check out our intro to eSIMs first to get your feet wet, but once you’re done, come back and watch [LaForge]’s talk.

In short, the “e” stands for “embedded”, and the eSIM is a self-contained computer that virtualises everything that goes on inside your plain-old SIM card and more. All of the secrets that used to be in a SIM card are stored as data on an eSIM. This flexibility means that there are three different types of eSIM, for machine-to-machine, consumer, and IoT purposes. Because the secret data inside the eSIM is in the end just data, it needs to be cryptographically signed, and the relevant difference between the three flavors boils down to three different chains of trust.

Whichever eSIM you use, it has to be signed by the GSM Alliance at the end of the day, and that takes up the bulk of the talk time in the end, and in the excellent Q&A period at the end where the hackers who’ve obviously been listening hard start trying to poke holes in the authentication chain. If you’re into device security, or telephony, or both, this talk will open your eyes to a whole new, tremendously complex, playground.