The EMac: Using Apple’s Forgotten Educational Mac In 2026

January 17, 2026 by Maya Posch 23 Comments

Beauty truly is in the eye of the beholder. (Credit: MattKC, YouTube)

What’s it like to use a 2002-era Apple eMac all-in-one in 2025? That’s what [MattKC] asked himself after obtaining one of these systems from a seller who ominously mentioned that it had been ‘left outside for years’.

The Apple iMac is a bit of a cult symbol, whether you’re talking about the iconic fruity iMac G3 or the desk lamp-like iMac G4, but few reminisce or actively collect the Apple eMac. Manufactured from 2002 to 2006, it featured the PowerPC 7450 (G4e) CPU with clock speeds ranging from 700 MHz to 1.42 GHz, as well as a 17″ CRT. In terms of design it was basically a bland iMac G3 that was firmly targeting the education markets to try and regain market share after Windows PCs had begun to eat its lunch there.

As for the model that [MattKC] purchased, it was this earliest model, featuring a 700 MHz PowerPC G4 CPU in addition to 640 MB SDRAM. Despite the seller’s description it seems to be in good nick with it firing right up, and even a glance inside after beating the challenge of 2.5 mm hex screws showed it to be in relatively good condition.

Unlike the iMac G3, you can play the Mac port of Halo on it, but the Minecraft port is very much not performant. With generally multimedia and gaming working well, it does show why the eMac was released, as it’s quite capable relative to an iMac G3 which would have struggled with the educational software of the era. We definitely hope that [MattKC] restores it to its full glory instead of ripping out its innards, as the neglected status of the eMac makes it much more likely to go extinct than PowerPC-based iMacs.

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How Accurate Is A 125 Year Old Resistance Standard?

January 16, 2026 by Maya Posch 44 Comments

Internals of the 1900 Evershed & Vignoles Ltd 1 ohm resistance standard. (Credit: Three-phase, YouTube)

Resistance standards are incredibly useful, but like so many precision references they require regular calibration, maintenance and certification to ensure that they stay within their datasheet tolerances. This raises the question of how well a resistance standard from the year 1900 performs after 125 years, without the benefits of modern modern engineering and standards. Cue the [Three-phase] YouTube channel testing a genuine Evershed & Vignoles Ltd one ohm resistance standard from 1900.

With mahogany construction and brass contacts it sure looks stylish, though the unit was missing the shorting pin that goes in between the two sides. This was a common feature of e.g. resistance decade boxes of the era, where you inserted pins to connect resistors until you hit the desired total. Inside the one ohm standard is a platinoid resistor, which is an alloy of copper, nickel, tungsten, and zinc. Based on the broad arrow mark on the bottom this unit was apparently owned by the UK’s Ordnance Board, which was part of what was then called the War Office.

After a quick gander at the internals, the standard was hooked up to a Keithley DMM7510 digital bench meter. The resistance standard’s ‘datasheet’ is listed on top of the unit on the brass plaques, including the effect of temperature on its accuracy. Adjusting for this, the measured ~1.016 Ω was within 1.6% tolerance, with as sidenote that this was with the unit not having been cleaned or otherwise having had maintenance performed on it since it was last used in service. Definitely not a bad feat.

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Testing A Continuous Printing Mod For The Bambu Lab A1 Mini

January 16, 2026 by Maya Posch 9 Comments

There are a few types of continuous 3D printing with FDM printers, with a conveyer belt and automatic build plate swapping the most common types. The advantage of build plate swapping is that it automates the bit where normally a human would have to come in to remove finished parts from the build plate. A recent entry here is the Chitu PlateCycler C1M which the [Aurora Tech] YouTube channel had over for a review. This kit bolts onto the Bambu Lab A1 Mini FDM printer and comes with four extra PEI build plates for a not unreasonable $79 (€69).

As also noted in the review video, this is effectively a clone of the original swapmod A1m kit, but a big difference is that the Chitu kit comes with all of the parts and doesn’t require you to print anything yourself.

The different plates are prepared using a special tool that inserts G-code between the plate changes. Moving the bed in a specific way triggers the switch that lifts the finished plate off the magnetic bed by the plastic grip on the plate and loads a fresh plate from the stack. Here it was found that a small tolerance issue prevented the last plate from being used, but some sandpaper fixed this. Other than that it was a fairly painless experience, and for e.g. multi-color prints with separated colors – as demonstrated – it would seem to be a great way to churn out the entire model without manual intervention or a lot of wasted filament.

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Battle Born LFP Battery Melts With New Problem

January 16, 2026 by Maya Posch 27 Comments

Following up on user-reported cases of Battle Born LiFePO4 batteries displaying very hot positive terminals, [Will Prowse] decided to buy a brand new one of these LFP batteries for some controlled cycle testing.

Starting with 30 cycles with a charging current of 49 A and a discharge current of 99 A, this put it well within the 100 A continuous rating for the battery. There is also a surge current rating of 200 A for thirty seconds, but that was not tested here.

What’s interesting about the results here is that instead of the positive terminal getting visibly discolored as with the previous cases that we reported on, [Will] saw severe thermal effects on the side of the negative terminal to the point where the plastic enclosure was deforming due to severe internal heating.

During testing, the first two charge-discharge cycles showed full capacity, but after that the measured capacity became extremely erratic until the battery kept disconnecting randomly. After letting the battery cool down and trying again with 80 A discharge current the negative terminal side of the enclosure began to melt, which was a good hint to stop testing. After this the battery also couldn’t be charged any more by [Will]’s equipment, probably due to the sketchy contact inside the battery.

It’s clear that the plastic spacer inside the terminal bus bar was once again the primary cause, starting a cascade which resulted in not only the enclosure beginning to char and melt, but with heat damage visible throughout the battery. Considering that the battery was used as specified, without pushing its limits, it seems clear that nobody should be using these batteries for anything until Battle Born fixes what appears to be the sketchiest terminal and bus bar design ever seen in a high-current battery.

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Trying Out The Allwinner-Based Walnut Pi SBC

January 16, 2026 by Maya Posch 35 Comments

When it comes to the term ‘Raspberry Pi clones’, the most that they really clone is the form factor, as nobody is creating clones of Broadcom VideoCore-based SoCs. At least not if they want to stay safe from Broadcom’s vicious legal team. That said, the Walnut Pi 1B single-board computer (SBC) that [Silly Workshop] recently took a gander at seems to be taking a fairly typical approach to a Raspberry Pi 4 form factor compatible board.

Part of Walnut Pi’s line-up, the Allwinner H616/H168-equipped 1B feels like it takes hints from both the RPi 4B and the Asus Tinkerboard, especially with its nicely colored GPIO pins. There’s also a beefier Walnut Pi 2B with an Allwinner T527 SoC that’s not being reviewed here. Translating the Chinese-language documentation for the board suggests that either the H616 or H618 may be installed, with both featuring a quad-core Cortex-A53, so in the ballpark of the Raspberry Pi 3.

There are also multiple RAM configurations, ranging from 1 GB of DDR3 to 4 GB of LPDDR4, with the 1 GB version being fun to try and run benchmarks like GeekBench on. Ultimately the impression was that it’s just another Allwinner SoC-based board, with a half-hearted ‘custom’ Linux image, no hardware acceleration due to missing (proprietary) Allwinner IP block drivers, etc.

While cheaper than a Raspberry Pi SBC, if you need anything more than the basic Allwinner H61* support and Ethernet/WiFi, there clearly are better options, some of which may even involve repurposing an e-waste Android TV box.

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Optimizing Software With Zero-Copy And Other Techniques

January 16, 2026 by Maya Posch 20 Comments

An important aspect in software engineering is the ability to distinguish between premature, unnecessary, and necessary optimizations. A strong case can be made that the initial design benefits massively from optimizations that prevent well-known issues later on, while unnecessary optimizations are those simply do not make any significant difference either way. Meanwhile ‘premature’ optimizations are harder to define, with Knuth’s often quoted-out-of-context statement about these being ‘the root of all evil’ causing significant confusion.

We can find Donald Knuth’s full quote deep in the 1974 article Structured Programming with go to Statements, which at the time was a contentious optimization topic. On page 268, along with the cited quote, we see that it’s a reference to making presumed optimizations without understanding their effect, and without a clear picture of which parts of the program really take up most processing time. Definitely sound advice.

And unlike back in the 1970s we have today many easy ways to analyze application performance and to quantize bottlenecks. This makes it rather inexcusable to spend more time today vilifying the goto statement than to optimize one’s code with simple techniques like zero-copy and binary message formats.

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Project Fail: Cracking A Laptop BIOS Password Using AI

January 15, 2026 by Maya Posch 51 Comments

Whenever you buy used computers there is a risk that they come with unpleasant surprises that are not of the insect variant. From Apple hardware that is iCloud-locked with the original owner MIA to PCs that have BIOS passwords, some of these are more severe than others. In the case of BIOS passwords, these tend to be more of an annoyance that’s easily fixed by clearing the CMOS memory, but this isn’t always the case as [Casey Bralla] found with a former student-issued HP ProBook laptop purchased off Facebook Marketplace.

Maybe it’s because HP figured that locking down access to the BIOS is essential on systems that find their way into the hands of bored and enterprising students, but these laptops write the encrypted password and associated settings to a separate Flash memory. Although a master key purportedly exists, HP’s policy here is to replace the system board. Further, while there are some recovery options that do not involve reflashing this Flash memory, they require answers to recovery questions.

This led [Casey] to try brute-force cracking, starting with a Rust-based project on GitHub that promised much but failed to even build. Undeterred, he tasked the Claude AI to write a Python script to do the brute-forcing via the Windows-based HP BIOS utility. The chatbot was also asked to generate multiple lists of unique passwords to try that might be candidates based on some human guesses.

Six months later of near-continuous attempts at nine seconds per try, this method failed to produce a hit, but at least the laptop can still be used, just without BIOS access. This may require [Casey] to work up the courage to do some hardware hacking and erase that pesky UEFI BIOS administrator password, proving at least that apparently it’s fairly good BIOS security.