Transceiver Reveals Unusual Components

March 8, 2025 by Al Williams 22 Comments

[MSylvain59] likes to tear down old surplus, and in the video below, he takes apart a German transceiver known as a U-600M. From the outside, it looks like an unremarkable gray box, especially since it is supposed to work with a remote unit, so there’s very little on the outside other than connectors. Inside, though, there’s plenty to see and even a few surprises.

Inside is a neatly built RF circuit with obviously shielded compartments. In addition to a configurable power supply, the radio has modules that allow configuration to different frequencies. One of the odder components is a large metal cylinder marked MF450-1900. This appears to be a mechanical filter. There are also a number of unusual parts like dogbone capacitors and tons of trimmer capacitors.

The plug-in modules are especially dense and interesting. In particular, some of the boards are different from some of the others. It is an interesting design from a time predating broadband digital synthesis techniques.

While this transceiver is stuffed with parts, it probably performs quite well. However, transceivers can be simple. Even more so if you throw in an SDR chip.

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Physical Computing Used To Be A Thing

March 8, 2025 by Elliot Williams 69 Comments

In the early 2000s, the idea that you could write programs on microcontrollers that did things in the physical world, like run motors or light up LEDs, was kind of new. At the time, most people thought of coding as stuff that stayed on the screen, or in cyberspace. This idea of writing code for physical gadgets was uncommon enough that it had a buzzword of its own: “physical computing”.

You never hear much about “physical computing” these days, but that’s not because the concept went away. Rather, it’s probably because it’s almost become the norm. I realized this as Tom Nardi and I were talking on the podcast about a number of apparently different trends that all point in the same direction.

We started off talking about the early days of the Arduino revolution. Sure, folks have been building hobby projects with microcontrollers built in before Arduino, but the combination of a standardized board, a wide-ranging software library, and abundant examples to learn from brought embedded programming to a much wider audience. And particularly, it brought this to an audience of beginners who were not only blinking an LED for the first time, but maybe even taking their first steps into coding. For many, the Arduino hello world was their coding hello world as well. These folks are “physical computing” natives.

Now, it’s to the point that when Arya goes to visit FOSDEM, an open-source software convention, there is hardware everywhere. Why? Because many successful software projects support open hardware, and many others run on it. People port their favorite programming languages to microcontroller platforms, and as they become more powerful, the lines between the “big” computers and the “micro” ones starts to blur.

And I think this is awesome. For one, it’s somehow more rewarding, when you’re just starting to learn to code, to see the letters you type cause something in the physical world to happen, even if it’s just blinking an LED. At the same time, everything has a microcontroller in it these days, and hacking on these devices is also another flavor of physical computing – there’s code in everything that you might think of as hardware. And with open licenses, everything being under version control, and more openness in open hardware than we’ve ever seen before, the open-source hardware world reflects the open-source software ethos.

Are we getting past the point where the hardware / software distinction is even worth making? And was “physical computing” just the buzzword for the final stages of blurring out those lines?

The Pentium Processor’s Innovative (and Complicated) Method Of Multiplying By Three, Fast

March 8, 2025 by Donald Papp 26 Comments

[Ken Shirriff] has been sharing a really low-level look at Intel’s Pentium (1993) processor. The Pentium’s architecture was highly innovative in many ways, and one of [Ken]’s most recent discoveries is that it contains a complex circuit — containing around 9,000 transistors — whose sole purpose is to multiply specifically by three. Why does such an apparently simple operation require such a complex circuit? And why this particular operation, and not something else?

Let’s back up a little to put this all into context. One of the feathers in the Pentium’s cap was its Floating Point Unit (FPU) which was capable of much faster floating point operations than any of its predecessors. [Ken] dove into reverse-engineering the FPU earlier this year and a close-up look at the Pentium’s silicon die shows that the FPU occupies a significant chunk of it. Of the FPU, nearly half is dedicated to performing multiplications and a comparatively small but quite significant section of that is specifically for multiplying a number by three. [Ken] calls it the x3 circuit.

The “x3 circuit”, a nontrivial portion of the Pentium processor, is dedicated to multiplying a number by exactly three and contains more transistors than an entire Z80 microprocessor.

Why does the multiplier section of the FPU in the Pentium processor have such specialized (and complex) functionality for such an apparently simple operation? It comes down to how the Pentium multiplies numbers.

Multiplying two 64-bit numbers is done in base-8 (octal), which ultimately requires fewer operations than doing so in base-2 (binary). Instead of handling each bit separately (as in binary multiplication), three bits of the multiplier get handled at a time, requiring fewer shifts and additions overall. But the downside is that multiplying by three must be handled as a special case.

[Ken] gives an excellent explanation of exactly how all that works (which is also an explanation of the radix-8 Booth’s algorithm) but it boils down to this: there are numerous shortcuts for multiplying numbers (multiplying by two is the same as shifting left by 1 bit, for example) but multiplying by three is the only one that doesn’t have a tidy shortcut. In addition, because the result of multiplying by three is involved in numerous other shortcuts (x5 is really x8 minus x3 for example) it must also be done very quickly to avoid dragging down those other operations. Straightforward binary multiplication is too slow. Hence the reason for giving it so much dedicated attention.

[Ken] goes into considerable detail on how exactly this is done, and it involves carry lookaheads as a key element to saving time. He also points out that this specific piece of functionality used more transistors than an entire Z80 microprocessor. And if that is not a wild enough idea for you, then how about the fact that the Z80 has a new OS available?

Get Into Meshtastic On The Cheap With This Tiny Node Kit

March 8, 2025 by Dan Maloney 15 Comments

There’s been a lot of buzz about Meshtastic lately, and with good reason. The low-power LoRa-based network has a ton of interesting use cases, and as with any mesh network, the more nodes there are, the better it works for everyone. That’s why we’re excited by this super-affordable Meshtastic kit that lets you get a node on the air for about ten bucks.

The diminutive kit, which consists of a microcontroller and a LoRa module, has actually been available from the usual outlets for a while. But [concretedog] has been deep in the Meshtastic weeds lately, and decided to review its pros and cons. Setup starts with flashing Meshtastic to the XIAO ESP32-S3 microcontroller and connecting the included BLE antenna. After that, the Wio-SX1262 LoRa module is snapped to the microcontroller board via surface-mount connectors, and a separate LoRa antenna is connected. Flash the firmware (this combo is supported by the official web flasher), and you’re good to go.

What do you do with your new node? That’s largely up to you, of course. Most Meshtastic users seem content to send encrypted text messages back and forth, but as our own [Jonathan Bennett] notes, a Meshtastic network could be extremely useful for emergency preparedness. Build a few of these nodes, slap them in a 3D printed box, distribute them to willing neighbors, and suddenly you’ve got a way to keep connected in an emergency, no license required.

The Road To Lucid Dreaming Might Be Paved With VR

March 7, 2025 by Donald Papp 26 Comments

Lucid dreaming is the state of becoming aware one is dreaming while still being within the dream. To what end? That awareness may allow one to influence the dream itself, and the possibilities of that are obvious and compelling enough that plenty of clever and curious people have formed some sort of interest in this direction. Now there are some indications that VR might be a useful tool in helping people achieve lucid dreaming.

The research paper (Virtual reality training of lucid dreaming) is far from laying out a conclusive roadmap, but there’s enough there to make the case that VR is at least worth a look as a serious tool in the quest for lucid dreaming.

One method of using VR in this way hinges on the idea that engaging in immersive VR content can create mild dissociative experiences, and this can help guide and encourage users to perform “reality checks”. VR can help such reality checks become second nature (or at least more familiar and natural), which may help one to become aware of a dream state when it occurs.

Another method uses VR as a way to induce a mental state that is more conducive to lucid dreaming. As mentioned, engaging in immersive VR can induce mild dissociative experiences, so VR slowly guides one into a more receptive state before falling asleep. Since sleeping in VR is absolutely a thing, perhaps an enterprising hacker with a healthy curiosity in lucid dreaming might be inspired to experiment with combining them.

We’ve covered plenty of lucid dreaming hacks over the years and there’s even been serious effort at enabling communication from within a dreaming state. If you ask us, that’s something just begging to be combined with VR.

This Laser Knows About Gasses

March 7, 2025 by Al Williams 5 Comments

What’s that smell? If you can’t tell, maybe a new laser system from CU Bolder and NIST can help. The device is simple and sensitive enough to detect gasses at concentrations down to parts per trillion.

The laser at the system’s heart is a frequency comb laser, originally made for optical atomic clocks. The laser has multiple optical frequencies in its output. The gas molecules absorb light of different wavelengths differently, giving each type of molecule a unique fingerprint.

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Tearing Down A Vintage Word Processor

March 7, 2025 by Al Williams 3 Comments

There was a time when the line between typewriters and word processing software was a bit fuzzy. [Poking Technology] found a Xerox 6040 which can’t decide what it is. It looks like a typewriter but has a monitor and a floppy drive, along with some extra buttons. You can watch him tear it down in the video below.

The old device uses a daisywheel type element, which, back then, was state of the art. A wheel had many spokes with letters and the printer would spin the wheel and then strike the plastic spoke.

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