You Can Now Run MS-DOS Applications On The Apple IIe

March 25, 2026 by Maya Posch 20 Comments

After a lot of debugging, [Seth Kushniryk] has managed to get the last issuess shaken out of his port of MS-DOS 2.0 to the Apple II, and has released the project to the public. If you have the requisite AD8088 or similar co-processor expansion card with onboard x86 CPU, this should be all you need to get started.

Although this co-processor card contains effectively a self-contained x86 system, its only I/O goes via the expansion bus, so it has to play nice with the 6502 CPU of the Apple II system. When we last reported on [Seth]’s efforts he had just managed to get MS-DOS 2.0 booting and basically in a barebones working state.

Since then he’s been working on the bridge program that provides communication between the 8088 on the card and the Apple II’s 6502, relocating it in RAM to enable high-resolution graphics, as well as other tweaks and optimizations. Also a lot of bug hunting, including an undocumented ProDOS constraint with a request count.

With all of this done it’s now possible to run basically any MS-DOS 2.0 compatible software, assuming it doesn’t try to write directly to video memory. This does limit the software selection somewhat, but back in the day it would probably have been amazing to have that 8 MHz 8088 purring along the 6502 to run both Apple and DOS software titles. Props to [Seth] for restoring this software functionality that had been lost to the ages.

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Testing Expensive Graphene-Reinforced Nylon Filament

March 24, 2026 by Maya Posch 11 Comments

Although usually nylon (generally PA6) filament is pretty cheap, there are some more exotic variants out there, such as the PA12-based Lyten 3D graphene filament that comes in at a cool $150 for a 1 kg spool. Worse for [Dr. Igor Gaspar] here was that the company doesn’t ship to the EU, and didn’t respond to emails about obtaining a sample for testing. Fortunately he got a spool via a different route, so that he could test whether this is the strongest nylon filament or not.

The full name for this filament is PA1205, though it’s not certain what the ’05’ part stands for. PA12 is a less moisture-sensitive version of PA6, however. Among the manufacturer’s claims are that it’s the strongest nylon filament, as well as very lightweight and heat-resistant. Interestingly the datasheet recommends printing with an 0.6 mm nozzle, which is the only major deviation from typical nylon FDM filaments. Of course, printing with an 0.4 mm nozzle had to be tried.

With a standard PA-CF preset in Bambu Lab’s slicer the printing of test parts worked without issues, which was promising. With load testing the filament made a good showing compared to average PA filaments, though as with most fiber reinforced filaments it’s more brittle than the pure material. Compared to PA-CF this PA1205 was much less brittle than PA-CF, however. Overall it’s not a bad filament, but for the asking price it’s a tough ask.

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US FCC Prohibits Approval Of New Foreign-Made Consumer Routers

March 24, 2026 by Maya Posch 90 Comments

The US Federal Communications Commission (FCC) is tasked with regulating both wired and wireless communications, which also includes a national security component. This is how previously the FCC tossed networking gear made by Huawei and foreign-manufactured drones onto its Covered List, effectively banning it from sale in the US. Now foreign-made consumer routers have been added to this list, barring explicit conditional approval on said list that would exempt them during a ‘transition phase’.

As per the FCC fact sheet, this follows after determination by an interagency body that such routers “pose unacceptable risks to the national security of the United States [..]”. This document points us to the National Security Determination PDF, which attempts to lay out the reasoning. In it is noted that routers are an integral part of every day life, and compromised routers are a major risk factor, ergo it follows that only US-manufactured routers are to be trusted.

These – so far fictional – US-manufactured consumer routers would have to feature ‘trusted supply chains’, which would seem to imply onshoring a large industrial base, though without specifying how deep this would have to go it’s hard to say what would be involved. The ‘supporting evidence’ section also only talks about firmware-related vulnerabilities, which would imply that US firmware developers do not produce CVEs.

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Using A Fiber Laser To Etch 0.1 Mm PCB Traces

March 24, 2026 by Maya Posch 14 Comments

Creating PCBs at home is quite easy these days (vias not withstanding), but even the best DIY methods usually can’t match the resolution offered by commercial PCB production lines. Large traces are easy enough to carve out of copper-backed FR1 or FR4 with even a mill, what if you need something more like 100 µm sized traces with similar clearance? This is what [Giangix] has been experimenting with, using both a fiber laser and chemical etching to see what approach gives the best results.

The thin copper clad boards are put on the 20 Watt fiber laser and held in place with the vacuum table that [Giangix] previously made, using the power of suction to make sure the board doesn’t move. The used laser specifies a minimum line width of 0.01 mm, so that’s clearly fine enough to engrave away the chemical resist layer that is sprayed on top of the copper layer.

After some experimentation, it was found that increasing the trace clearance between the 0.1 mm traces to a hair above 0.1 mm was necessary for the subsequent chemical etching step to work the best, as otherwise some copper was still likely to remain. The chemical etching bath mixture consists of hydrochloric acid and hydrogen peroxide, in a ratio of 2 mL water to 2 mL 30% HCl and 2 drops of 35% H2O2. This is agitated for 90 s to get a pretty good result.

Although the final resistance measurements on the traces is a bit higher than theoretical, comments suggest that maybe some of the copper got removed along with the removal of the resist layer. Perhaps the most interesting question here is whether directly ablating the copper using the fiber laser would give even better results and bypass the etching chemicals.

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Low Self-Discharge, High-Voltage Supercapacitors Using Porous Carbon

March 23, 2026 by Maya Posch 13 Comments

Supercapacitors rely mostly on double-layer capacitance to bridge the divide between chemical batteries and traditional capacitors, but they come with a number of weaknesses. Paramount among these are their relatively low voltage of around 2.7 V before their electrolyte begins to decompose, as well as their relatively high rates of self-discharge. Here a new design using lignin-derived porous carbon electrodes and a fluorinated diluent was demonstrated by [Shichao Zhang] et al., as published in Carbon Research, that seems to address these issues.

Most notable are the relatively high voltage of 4 V, an energy density of 77 Wh/kg and a self-discharge rate that’s much slower than that of conventional supercapacitors. In comparison with these supercapacitors, these demonstrated versions are also superior in terms of recharge cycles with 90% of capacity remaining after 10,000 cycles, which together with their much higher energy density should prove to be quite useful.

This feat is accomplished by using lignin as the base for the carbon electrodes to make a highly porous surface, along with the new electrolyte formulation consisting of a lithium salt (LiBF₄) dissolved in sulfolane with TTE as a non-solvating diluent. The idea of using lignin-derived carbon for such a purpose has previously been pitched by [Jia Liu] et al. in 2022 and [Zhihao Ding] in 2025, with this seemingly one of the first major applications we may be seeing.

Although the path towards commercialization from a lab-assembled prototype is a rough one, we may be seeing some of these improvements come to supercapacitors near you sooner rather than later.

Storing Solar Energy As Ice For Air Conditioning

March 22, 2026 by Maya Posch 84 Comments

Thermal energy storage is pretty great, as phase-change energy storage is very consistent with its energy output over time, unlike chemical batteries. You also get your pick from a wide range of materials that you can either heat up or cool down to store energy. Here, the selection is mostly dependent on how you wish to use that energy at a later date. [Hyperspace Pirate] is mostly interested in cooling down a house, on account of living in Florida.

As can be seen in the top image, the basic setup is pretty straightforward. PV solar power charges a battery until it’s fully charged. Then an MCU triggers a relay on the AC inverter, which then starts the cooling compressor on the water reservoir. This proceeds to phase change the water from a liquid into ice. The process can later be reversed, which will draw thermal energy out of the surrounding air and thus provide cooling.

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