[Usagi Electric] and his home brew computer

TMS9900-based Home Brew Computer

November 17, 2025 by John Elliot V 3 Comments

[Usagi Electric] is known for minicomputers, but in a recent video, he shows off his TMS9900-based homebrew computer. The TMS9900 CPU was an early 16-bit CPU famously used in the old TI-99/4A computer, but as the video points out, it wasn’t put to particularly good use in the TI-99/4A because its RAM was hidden behind an inefficient interface and it didn’t leverage its 16-bit address space.

The plan is for this computer to have 2K words of ROM, 6K words of RAM, and three serial lines: one for the console terminal, another for a second user console terminal, and the third for access to a tape drive.

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Reverse Engineering The Miele Diagnostic Interface

November 17, 2025 by Maya Posch 15 Comments

Since modern household appliances now have an MCU inside, they often have a diagnostic interface and — sometimes — more. Case in point: Miele washing machines, like the one that [Severin] recently fixed, leading to the firmware becoming unhappy and refusing to work. This fortunately turned out to be recoverable by clearing the MCU’s fault memory, but if you’re unlucky, you will have to recalibrate the machine, which requires very special and proprietary software.

Naturally, this led [Severin] down the path of investigating how exactly the Miele Diagnostic Utility (MDU) and the Program Correction (PC) interface communicate. Interestingly, the PC interface uses an infrared LED/receiver combination that’s often combined with a status LED, as indicated by a ‘PC’ symbol. This interface uses the well-known IrDA standard, but [Severin] still had to track down the serial protocol.

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A photo of a brushed motor and brushless motor with a brushless controller board

An Introduction To DC Motor Technology

November 16, 2025 by John Elliot V 3 Comments

[Thinking Techie] takes us back to basics in a recent video explaining how magnets, coils, brushed DC motors, and brushless DC motors work. If this is on your “to learn” list, or you just want a refresher, you can watch the video below. It’ll be ten minutes well-spent.

The video covers the whole technology stack behind the humble DC motor in its various incarnations. Starting with basic magnetic effects, it then proceeds through 2-wire brushed DC motors and finally into 3-wire brushless DC motors (BLDC motors).

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Supersized Calculator Brings The Whole Intel 4004 Gang Together

November 16, 2025 by Tyler August 13 Comments

Though mobile devices and Apple Silicon have seen ARM-64 explode across the world, there’s still decent odds you’re reading this on a device with an x86 processor — the direct descendant of the world’s first civilian microprocessor, the Intel 4004. The 4004 wasn’t much good on its own, however, which is why [Klaus Scheffler] and [Lajos Kintli] have produced super-sized discrete chips of the 4001 ROM, 4002 RAM, and 4003 shift register to replicate a 1970s calculator at 10x the size and double the speed, all in time for the 4004’s 50th anniversary.

We featured this project a couple of years back, when it was just a lonely microprocessor. Adding the other MSC-4 series chips enabled the pair to faithfully reproduce the logic of a Busicom 141-PF calculator, the very first to market with Intel’s now-legendary microprocessor. Indeed, this calculator is the raison d’etre for the 4004: Busicom commissioned the whole Micro-Computer System 4-bit (MCS-4) set of chips specifically for this calculator. Only later, once they realized what they had made, did Intel buy the rights back from the Japanese calculator company, and the rest, as they say, is history.

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Hackaday Links: November 16, 2025

November 16, 2025 by Dan Maloney 11 Comments

We make no claims to be an expert on anything, but we do know that rule number one of working with big, expensive, mission-critical equipment is: Don’t break the big, expensive, mission-critical equipment. Unfortunately, though, that’s just what happened to the Deep Space Network’s 70-meter dish antenna at Goldstone, California. NASA announced the outage this week, but the accident that damaged the dish occurred much earlier, in mid-September. DSS-14, as the antenna is known, is a vital part of the Deep Space Network, which uses huge antennas at three sites (Goldstone, Madrid, and Canberra) to stay in touch with satellites and probes from the Moon to the edge of the solar system. The three sites are located roughly 120 degrees apart on the globe, which gives the network full coverage of the sky regardless of the local time.

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The Simplest Ultrasound Sensor Module, Minus The Module

November 16, 2025 by Tyler August 2 Comments

Just about every “getting started with microcontrollers” kit, Arduino or otherwise, includes an ultrasonic distance sensor module. Given the power of microcontrollers these days, it was only a matter of time before someone asked: “Could I do better without the module?” Well, [Martin Pittermann] asked, and his answer, at least with the Pi Pico, is a resounding “Yes”. A micro and a couple of transducers can offer a better view of the world.

The project isn’t really about removing the extra circuitry on the SR-HC0, since there really isn’t that much to start. [Martin] wanted to know just how far he could push ultrasound scanning technology using RADAR signal processing techniques. Instead of bat-like chirps, [Martin] is using something called Frequency-Modulated Continuous Wave, which comes from RADAR and is exactly what it sounds like. The transmitter emits a continuous carrier wave with a varying frequency modulation, and the received wave is compared to see when it must have been sent. That gives you the time of flight, and the usual math gives you a distance.

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The King Of Rocket Photography

November 16, 2025 by Al Williams 24 Comments

If you are a nerdy kid today, you have your choice of wondrous gadgets and time wasters. When we were nerdy kids, our options were somewhat limited: there was ham radio, or you could blow things up with a chemistry set. There were also model rockets. Not only were model rockets undeniably cool, but thanks to a company called Estes, you could find ready-to-go kits and gear that made it possible to launch something into the heavens, relatively speaking. But what about photographic proof? No live streams or digital cameras. But there was the Estes AstroCam 100. [Bill Engar] remembers the joy of getting film from your rocket developed.

Of course, photography was another nerdy kid staple, so maybe you did your own darkroom work. Either way, the Astrocam 110 was a big improvement over the company’s earlier Camroc. In 1965, if you wanted to fly Camroc, you had to cut a 1.5-inch piece of film in a darkroom and mount it just to get one terrible black-and-white photo. Or, you could buy the film canisters loaded if you had the extra money, which, of course, you didn’t.

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