2026-02-22 14:00:38
Theoretically a belt drive makes for a great upgrade to a bicycle, as it replaces the heavier, noisy and relatively maintenance-heavy roller chain with a zero-maintenance, whisper-quiet and extremely reliable belt that’s rated at an amazing 20-30,000 km before needing a replacement. Of course, that’s the glossy marketing brochure version of reality, which differed significantly from what [Tristan Ridley] experienced whilst cycling around the globe.
Although initially he was rather happy with his bike, its sealed car-like Pinion gearbox and Gates carbon belt drive system, while out in the wilds of Utah he had a breakdown when the belt snapped. When the spare belt that he had carried with him for the past months also snapped minutes later after fitting it on, it made him decide to switch back to the traditional bush roller chain.
Despite this type of chain drive tracing its roots all the way back to Leonardo da Vinci, they actually offer many advantages over the fancy carbon-fiber-reinforced polyurethane belt. Although with the Pinion gearbox the inability to use a derailleur gearing system is no big deal, [Tristan] found that the ‘zero maintenance’ part of the belt was not true for less hospitable roads
A big issue was that of abrasive dust, which created a very noisy coating on the belt that’d have to be regularly cleaned off with precious water, or by having silicone lubricant sprayed on the belt. Even with all that care he found that the belt would snap after about 8,000 km, well below the rated endurance.
When it came to super-sticky mud, called peanut butter mud for good reasons, he found that chains also cope much better with this, as the mud will just squeeze out of the chain and be forced off the sprocket, whereas the belt will happily keep compacting the mud onto the contact surfaces, increasing belt tension and requiring constant cleaning to not become hopelessly stuck.
The Utah breakdown also showed why these belts are actually very fragile: the replacement belt had been packed away folded-up for a few months at that point in the luggage, and during storage the carbon fibers had become compromised to the point where the belt just snapped after a few minutes of use. A metal chain will happily be stored away for as long as you can keep it away from corrosion, and fold up very compactly.
Another awesome feature of roller chains is that they’re super-modular, allowing you to carry spare links and such with you for in-the-field repairs, while even the most remote bicycle store in any country can help you out with maintenance and repairs, unlike the special and highly custom belts that need to be shipped in by courier.
Of all the bicycle technologies that [Tristan] has used, it seems that only this drive belt has been an outright disappointment. The sealed gearbox would seem to be a massive improvement over finicky derailleurs, and hydraulic brakes are reliable and common enough that they haven’t been an issue so far.
His conclusion is that bicycle drive belts are fine if you do city driving, where they probably will last the rated kilometers, but they rapidly fall apart in even slightly adverse conditions.
2026-02-22 11:00:34
[Hans Rosenberg] has a new video talking about a nasty side effect of using resistors: noise. If you watch the video below, you’ll learn that there are two sources of resistor noise: Johnson noise, which doesn’t depend on the construction of the resistor, and 1/f noise, which does vary depending on the material and construction of the resistor.
In simple terms, some resistors use materials that cause electron flow to take different paths through the resistor. That means that different parts of the signal experience slightly different resistance values. In simple applications, it won’t matter much, but in places where noise is an important factor, the 1/f or excess noise contributes more to errors than the Johnson noise at low frequencies.
[Hans] doesn’t just talk the math. He also built a simple test rig that lets him measure the 1/f noise with some limitations. While you might pretend that all resistors are the same, the test shows that thick film resistors produce much more noise than other types.
The video shows some rule-of-thumb lists indicating which resistors have better noise figures than others. Of course, resistors are only one source of noise in circuits. But they are so common that it is easy to forget they aren’t as perfect as we pretend in our schematics.
Want to learn more about noise? We can help. On the other hand, noise isn’t always a bad thing.
2026-02-22 08:00:15
An interesting detail about the Intel 8087 floating point processor (FPU) is that it’s a co-processor that shares a bus with the 8086 or 8088 CPU and system memory, which means that somehow both the CPU and FPU need to know which instructions are intended for the FPU. Key to this are eight so-called ESCAPE opcodes that are assigned to the co-processor, as explained in a recent article by [Ken Shirriff].
The 8087 thus waits to see whether it sees these opcodes, but since it doesn’t have access to the CPU’s registers, sharing data has to occur via system memory. The address for this is calculated by the CPU and read from by the CPU, with this address registered by the FPU and stores for later use in its BIU register. From there the instruction can be fully decoded and executed.
This decoding is mostly done by the microcode engine, with conditional instructions like cos featuring circuitry that sprawls all over the IC. Explained in the article is how the microcode engine even knows how to begin this decoding process, considering the complexity of these instructions. The biggest limitation at the time was that even a 2 kB ROM was already quite large, which resulted in the 8087 using only 22 microcode entry points, using a combination of logic gates and PLAs to fully implement the entire ROM.
Only some instructions are directly implemented in hardware at the bus interface (BIU), which means that a lot depends on this microcode engine and the ROM for things to work half-way efficiently. This need to solve problems like e.g. fetching constants resulted in a similarly complex-but-transistor-saving approach for such cases.
Even if the 8087 architecture is convoluted and the ISA not well-regarded today, you absolutely have to respect the sheer engineering skills and out-of-the-box thinking of the 8087 project’s engineers.
2026-02-22 05:00:24
If you’re interested in extraterrestrial life, these past few years have given an embarrassment of places to look, even in our own solar system. Mars has been an obvious choice since before the Space Age; in the orbit of Jupiter, Europa’s oceans have been of interest since Voyager’s day; the geysers of Enceladus give Saturn two moons of interest, if you count the possibility of a methane-based chemistry on Titan. Even faraway Neptune’s giant moon Triton probably has an ocean layer deep inside. Now the planet Uranus is getting in on the act, offering its moon Miranda for consideration in a kinda-recent study in the Planetary Science Journal.
Even if you’re into astronomy, it may seem like this is coming out of left field. “Miranda, really? What new data could we possibly have on a moon of Neptune nobody’s visited since the 1980s?” Well, none, really. This study relies on reexamining the data collected during the Voyager 2 encounter and trying to make sense of the chaotic, icy world that the space probe revealed.
The faults and other features on Miranda indicated it was geologically active at some point; this study tries to recreate the moon’s history through computer modelling to find that Miranda probably had a ≥100 km thick ocean sometime in the last 100-500 million years, and that while some of it has likely frozen since, tidal heating could very well keep a layer of liquid water within the moon’s interior. Since the moon itself is only 470 km (290 mi) in diameter, a 100km deep ocean layer would actually be a huge proportion of its volume.
Right now, the over-optimistic thinking is that “water means life”, since that’s how it seems to work on Earth. It remains to be seen if Miranda, or indeed any of the icy moons, ever evolved so much as a microbe. Aside from the supposed presence of liquid dihydrogen monoxide, there’s nothing to suggest they have. Finding out is going to take a while: even with boots — er, robots — on the ground, Mars isn’t giving up that secret easily. Still, if we’re able to discover irrefutable evidence for such extraterrestrial life, it will provide an important constraint on one term of The Drake Equation: what fraction of worlds develop life. That by itself won’t tell us “are we alone,” but it will be interesting.
Of course, even if all these worlds are barren now, they might not be for long, once our probes start visiting.
Story via Earth.com
Header image: Miranda, imaged by Voyager 2. Credit NASA/JPL-Caltech
2026-02-22 02:00:53
Although digital computers are – much like their human computer counterparts – about performing calculations, another crucial element is that of memory. After all, you need to fetch values from somewhere and store them afterwards. Sometimes values need to be stored for long periods of time, making memory one of the most important elements, yet also one of the most difficult ones. Back in the 1950s the storage options were especially limited, with a 1959 Bell Labs film reel that [Connections Museum] digitized running through the bleeding edge of 1950s storage technology.
After running through the basics of binary representation and the difference between sequential and random access methods, we’re first taking a look at punch cards, which can be read at a blistering 200 cards/minute, before moving onto punched tape, which comes in a variety of shapes to fit different applications.
Electromechanical storage in the form of relays are popular in e.g. telephone exchanges, as they’re very fast. These use two-out-of-five code to represent the phone numbers and corresponding five relay packs, allowing the crossbar switch to be properly configured.
After these types of memory, we move on to magnetic memory, in the form of well-known magnetic tape that provide mass storage in relatively little space. There is also the magnetic drum, which is much like a very short and very fast tape and provides e.g. working memory. This is what e.g. the Bendix G-15 uses for its clock signal and working memory, while magnetic tape and punched tape are used for application and data storage.
Next we cover magnetic-core memory, which stores a magnetic orientation in its ferrite rings or on a ferrite plate. This is non-volatile memory, but has low bit density and performs destructive reads, preventing its use beyond the 1970s. Today’s NAND Flash memory has significant overlap with core memory in its operating principles, both in its advantages and disadvantages.
An interesting variation on core memory is Twistor memory, which saw brief use during the late 1960s and early 1970s. Invented by Bell Labs, it was supposed to make for cheaper core-like memory, but semiconductor memory wiped out its business case, along with the similar bubble memory. An interesting feature of Twistor memory was the ability to add write-inhibit cards containing permanent magnets.
Fascinatingly, a kind of crude mask ROM is also demonstrated, before we move on to the old chestnut of vacuum tubes. Demonstrated is a barrier-grid tube, which uses electrons to create an electrostatic charge on a mica surface. This electron beam is also used to read the value, which is naturally destructive, making it somewhat similar to core memory in its speed and functionality.
Finally, we get the flying-spot store system, which is a type of optical digital memory. This is reminiscent of optical disc systems like the Compact Disc, and a reminder of all the amazing breakthroughs that we’d be seeing over the next decades.
Perhaps the best part about this video is that it shows the world as it sidled still mostly unaware towards these big changes. Memory storage was still the realm of largely hand-assembled, macro-sized devices, vacuum tubes and chunky electromechanical relays. Only a few years after this video was released, we’d see semiconductor technology turn the macro into micro, by the 1970s nerds would be fighting over who had the most RAM in their home computers, and CD-ROMs would set the world of computer storage and home game consoles ablaze by the 1990s with literally hundreds of MBs of storage per very cheap disc.
2026-02-21 23:00:19
Your project doesn’t necessarily have to be a refined masterpiece to have an impact on the global hacker hivemind. Case in point: this great demo of using a 64-point time-of-flight ranging sensor. [Henrique] took three modules, plugged them into a breadboard, and wrote some very interactive Python code that let him put them all through their paces. The result? I now absolutely want to set up a similar rig and expand on it.
That’s the power of a strong proof of concept, and maybe a nice video presentation of it in action. What in particular makes [Henrique]’s POC work is that he’s written the software to give him a number of sliders, switches, and interaction that let him tweak things in real time and explore some of the possibilities. This exploratory software not only helped him map out what directions to go, but they also work in demo mode, when he’s showing us what he has learned.
But the other thing that [Henrique]’s video does nicely is to point out the limitations of his current POC. Instantly, the hacker mind goes “I could work that out”. Was it strategic incompleteness? Either way, I’ve been nerd-sniped.
So are those the features of a good POC? It’s the bare minimum to convey the idea, presented in a way that demonstrates a wide range of possibilities, and leaving that last little bit tantalizingly on the table?
