Diagnosing A Mysterious Fault With A Commodore 1541 Disk Drive

March 9, 2026 by Maya Posch 2 Comments

Some PCB corrosion on the bottom of the 1541 drive. (Credit: TheRetroChannel, YouTube)

Recently [TheRetroChannel] came across an interesting failure mode on a Commodore 1541 5.25″ floppy disk drive, in the form of the activity LED blinking just once after power-up with the drive motor continuously spinning. Since the Flash Codes that Commodore implemented and bothered to document start at 2 flashes (for RAM-related Zero Page), this raised the question of what fault this drive had, and whether a single flash is some kind of undocumented error code.

A cursory check showed that the heads were okay and not shorted, ruling out a common fault with the used floppy mechanism. Cleaning up the corrosion on IC sockets and similar basic operations were performed next, without making a change, nor did removing the ICs to induce it to produce the documented error codes, but this helped narrow down the potential causes. Especially after swapping in known-good ICs failed to make a difference. One possibility was that the drive was boot looping, as the activity LED is lit up once on boot.

Some probing around with an oscilloscope between the faulty and a working drive seemed to point to a faulty RAM IC, but while probing the faulty drive suddenly initialized successfully. After some more poking around it appeared that the drive was fine after it had a chance to warm up, which just deepened the mystery.

The drive did talk to a C64 with diagnostic cartridge at this point, but would often glitch out. Ultimately it appears that a dodgy IC socket and a few bad traces were to blame for the behavior, making it an ‘obvious in hindsight’ repair. The bottom of the PCB had some clear corrosion on it, but the affected traces were apparently still hanging on for dear life with the drive still initializing once warmed up.

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Building A Class 100 Semiconductor Cleanroom Inside A Shed

March 9, 2026 by Maya Posch 16 Comments

Just your typical backyard cleanroom shed. (Credit: Dr. Semiconductor, YouTube)

Most people see that garden shed as little more than a place to store some gardening tools in, but if you’re like [Dr. Semiconductor], then what you see is a potential cleanroom for semiconductor manufacturing. As ridiculous as this may sound, the basic steps behind the different levels of cleanrooms work just as well for a multi-million dollar fab as they do for for a basic shed.

Key to everything is HEPA filtration along with positive pressure, to constantly push clean air into the cleanroom, while preventing dirty air from flowing in. The shed was also split into two sections, the first room once you enter it being the the gowning room. This is where you change into cleanroom gear before you transition into the cleanroom.

In addition to the flame-resistant drywalls, a water-based epoxy coating was applied to the insides of the cleanroom walls to make it smooth and free of debris. The HEPA filtration system constantly filters the shed’s air along with some fresh outside air, while an airconditioning unit ensures that the temperature remains constant.

The measured >0.5 µm particle contamination inside the shed turned out to be enough for a FED STD 209E equivalent of Class 100, which is ISO 5 class with a maximum of 3,520 particles/m³. For comparison, room air is ISO 9 with max 35,200,000 particles/m³. At ISO 5 it’s good enough to do some semiconductor R&D laboratory things, which is what [Dr. Semiconductor]’s channel is – shockingly – about.

Thanks to [Thayer] for the tip.

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Reverse-Engineering The Bluetooth Fichero Thermal Label Printer Protocol

March 9, 2026 by Maya Posch 19 Comments

It’s hard to deny that label printers have become more accessible than ever, but an annoying aspect of many of these cheap units is that their only user interface is a proprietary smartphone app connected via Bluetooth. The Fichero-branded label printer that [0xMH] obtained for a mere 10 Euro at a store in the Netherlands was much the same, with an associated app that doesn’t just bind it to smartphones, but also requires no fewer than 26 permissions. Obviously this required some reverse-engineering of the BLE protocol.

The fruits of this reverse-engineering effort can be found in the GitHub repository, with the most interesting part probably being that this Fichero is just one of many relabeling of generic label printers, this one being an AiYin D11, by Xiamen Printer Future Technology. This means that other iterations of this D11 will work exactly the same, as they all use the same ‘LuckPrinter’ SDK.

[0xMH] provides a Web GUI to talk with a local D11 printer, though you can also use the Python scripts, or of course implement the protocol using your favorite language and frameworks, so that you can finally control a cheap label printer from a PC or even BLE-equipped MCU like the software gods intended.

Thanks to [T-ice] for the tip.

How Usable Is Windows 98 In 2026?

March 8, 2026 by Maya Posch 46 Comments

With the RAM and storage crisis hitting personal computing very hard – along with new software increasingly suffering the effects of metastasizing ‘AI’ – more people than ever are pining for the ‘good old days’. For example, using that early 2000s desktop PC with Windows 98 SE might now seem to be a viable alternative in 2026, because it couldn’t possibly make things worse. Or could it? As a reality check, [SteelsOfLiquid] over on YouTube gave this setup a whirl.

The computer of choice is a very common Dell Dimension 2100, featuring a zippy 1.1 GHz Intel Celeron, 256 MB of DDR1, and a spacious 38 GB HDD. Graphics are provided by the iGPU in the Intel i810 chipset, all in a compact, 6.9 kg light package. As an early Windows XP PC, this gives Windows 98 SE probably a pretty solid shot at keeping up with the times. At least the early 2000s, natch.

Of course, there is a lot of period-correct software you can install, such as Adobe Photoshop 5, MS Office 97 (featuring everyone’s beloved Clippy), but a lot of modern software also runs, with the Retro Systems Revival blog documenting many that still run on Win98SE in some manner, including Audacity 2.0. This makes it totally suitable for basic productivity things.

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Restoring A Commodore PET 3032 In Rough Condition

March 8, 2026 by Maya Posch 11 Comments

The restored PET/CBM 3032. (Credit: Drygol, retrohax.net)

The Commodore CBM 3032 is a successor to the original Commodore PET 2001, yet due a conflicting trademark issue with Philips these first European PETs were called ‘CBM’ instead. Hence the labeling on the CBM 3032 that [Drygol] had in for a restoration, which would have been produced somewhere between 1979 and the cessation of its manufacturing a few years later. This former machine of the University of Szcezecin in Poland had languished in a basement until a local demoscene group came across it and wanted to use it, after a restoration.

Although at first glance from just the front it didn’t look too shabby, problems were apparent from just a walkaround, including rusty and buckled paneling, showing that the time spent in storage had not done it any favors. Internally there was decades worth of dust, along with a dodgy potentiometer, cold joints and some PCB-level bodges that may or may not have been there from the factory.

The main case was disassembled by drilling out the rivets to gain full access to every nook and cranny, allowing for a good cleaning and repainting prior to putting in fresh rivets. On the PCB side of things, a potentiometer and an LM340KC-12 linear regulator in a TO-3 package had to be replaced, after which the system managed to boot reliably once in every three attempts.

Fixing this took basically cleaning all contacts and IC sockets, as well as refurbishing the keyboard, with corrosion and the occasional broken trace causing a lot of grief. Ultimately the system was restored and ready to be put into demoscene service.

Building A Super-Compact Cistercian Numerals Clock

March 8, 2026 by Maya Posch 12 Comments

Around the thirteenth century CE, European society was in the midst between transitioning from Roman numerals to the Arabic numerals that we use today. Less remembered are the Cistercian numerals, which [BigCrimping] used for their most recent project in the form of a rather unique clock.

The Cistercian numeral system was developed by the Cistercian monastic order in the 13th century, forming a rather unique counterpoint to the Arabic numeral system. Although Arabic numerals are already significantly more compact than Roman numerals, Cistercian numerals up the ante by being capable of displaying any number between 1 and 9,999 with a single glyph.

Although for a simple 24-hour clock you don’t need to use more than a fraction of the possible glyphs, there is the complication of the Cistercian numerals not having a zero glyph, but that invites an even better take. For the version that [BigCrimping] made there are namely two glyphs that encode date and time, with the left glyph a counter for blocks of two hours and the right for seconds from 1 through 7200.

The clock is based around MAX6969 LED drivers and an ESP32 MCU on a custom PCB, with the design files including the 3D-printed enclosure available in the repository.

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How The Chornobyl NPP Got Modernized In The 1990s

March 7, 2026 by Maya Posch 5 Comments

During the 1990s the Chornobyl Nuclear Power Plant – formerly the Chernobyl NPP – continued operating with its remaining three RBMK reactors, but of course the 1970s-era automation with its very limited SKALA computer required some serious modernization. What was interesting here is that instead of just replacing this entire Soviet-era mainframe with a brand-new 1990s one, the engineers responsible opted to build a new system – called DIIS – around it. This is detailed in a recent video by the [Chornobyl Family] on YouTube.

This SKALA industrial control system was previously detailed in a video, covering this 24-bit mainframe computer and its many limitations. It wasn’t quite a real-time control system, but it basically did what it was designed to do. Since at the time it was not clear for how long these three RBMKs would be kept running, they didn’t want to go overboard with investments either.

Ultimately Unit 2 only was active until 1991 due to a turbine fire, Unit 1 until 1996 and Unit 3 was shutdown for the last time in 2000, so this a sensible decision. During those years, an auxiliary information-measurement system (DIIS) was the big upgrade, which got bridged into SKALA via a Ukrainian-made SM-1210 minicomputer, with the latter connected to an 80386 PC which itself was connected to an ARCnet hub.

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