The Unusual Pi Boot Process Explained

If you’ve ever experimented with a microprocessor at the bare metal level, you’ll know that when it starts up, it will look at its program memory for something to do. On an old 8-bit machine, that program memory was usually an EPROM at the start of its address space, while on a PC, it would be the BIOS or UEFI firmware. This takes care of initialising the environment in both hardware and software, and then loading the program, OS, or whatever the processor does. The Raspberry Pi, though, isn’t like that, and [Patrick McCanna] is here to tell us why.

The Pi eschews bringing up its ARM core first. Instead, it has a GPU firmware that brings up the GPU. It’s this part of the chip that then initialises all peripherals and memory. Only then does it activate the ARM part of the chip. As he explains, this is because the original Pi chip, the BCM2835, is a set-top-box chip. It’s not an application processor at all, but a late-2000s GPU that happened to have an ARM core on a small part of its die, so the GPU wakes first, not the CPU. Even though the latest versions of the Pi have much more powerful Broadcom chips, this legacy of their ancestor remains. For most of us using the board it doesn’t matter much, but it’s interesting to know.

Fancy trying bare metal Pi programming? Give it a go. We’ve seen some practical projects that start at that level.

hackaday.com/2025/12/21/the-un…

Hackaday Links: December 21, 2025

It’s amazing how fragile our digital lives can be, and how quickly they can fall to pieces. Case in point: the digital dilemma that Paris Buttfield-Addison found himself in last week, which denied him access to 20 years of photographs, messages, documents, and general access to the Apple ecosystem. According to Paris, the whole thing started when he tried to redeem a $500 Apple gift card in exchange for 6 TB of iCloud storage. The gift card purchase didn’t go through, and shortly thereafter, the account was locked, effectively bricking his $30,000 collection of iGadgets and rendering his massive trove of iCloud data inaccessible. Decades of loyalty to the Apple ecosystem, gone in a heartbeat.

As for why the account was locked, it appears that the gift card Paris used had been redeemed previously — some kind of gift card fraud, perhaps. But Paris only learned that after the issue was resolved. Before that, he relates five days of digital limbo and customer support hell, which included unhelpful advice such as creating a new account and starting over from scratch, which probably would have led to exactly the same place, thanks to hardware linking of all his devices to the nuked account. The story ends well, perhaps partly due to the victim’s high profile in the Apple community, but it’s a stark lesson in owning your digital data. If they’re not your computer, they’re not your files, and if someone like Paris can get caught up in a digital disaster like this, it can happen to anyone.

Hackaday isn’t the place readers normally turn to for fiction, but we wanted to call attention to a piece of short fiction with a Hackaday angle. Back in June, Canadian writer Kassandra Haakman contacted us about a short story she wrote focused on the 1989 geomagnetic storm that temporarily wiped out the electric grid in Québec. She wanted permission to quote our first-hand description of that night’s aurorae, which we wrote a bit about on these pages. We happily granted permission for the quote, on condition that she share a link to the article once it’s published. The story is out now; it’s a series of vignettes from that night, mostly looking at the disorientation of waking up to no electricity but a sky alive with light and energy. Check it out — we really enjoyed it.

Speaking of solar outbursts, did 6,000 Airbus airliners really get grounded because of solar storms? We remember feeling a bit skeptical when this story first hit the media, but without diving into it at the time, cosmic rays interfering with avionics seemed as good an explanation as anything. But now an article in Astronomy.com goes into much more detail about this Emergency Airworthiness Directive and exactly what happened to force aviation authorities to ground an entire fleet of planes. The article speaks for itself, but to summarize, it appears that the EAD was precipitated by an “uncommanded and limited pitch down” event on a JetBlue flight on October 10 that injured several passengers. The post-incident analysis revealed that the computer controlling the jet’s elevators and ailerons may have suffered a cosmic-ray-induced “bit flip,” temporarily scrambling the system and resulting in uncommanded movement of the control surfaces. The article goes into quite some detail about the event and the implications of increased solar activity for critical infrastructure.

And finally, if you’ve been paying attention to automotive news lately, it’s been kind of hard to miss the brewing public relations nightmare Toyota is facing over the rash of engine failures affecting late-model Tundra pickups. The 3.4-liter V6 twin-turbo engine that Toyota chose to replace the venerable but thirsty 5.7-liter V8 that used to power the truck is prone to sudden death, even with very few miles on the odometer. Toyota has been very cagey about what exactly is going wrong with these engines, but Eric over at “I Do Cars” on YouTube managed to get his hands on an engine that gave up the ghost after a mere 38,000 miles, and the resulting teardown is very interesting. Getting to the bottom of the problem required a complete teardown of the engine, top to bottom, so all the engineering behind this power plant is on display. Everything looked good until the very end; we won’t ruin the surprise, but suffice it to say, it’s pretty gnarly. Enjoy!

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hackaday.com/2025/12/21/hackad…

𝗜𝗔 𝗔𝗟 𝗖𝗢𝗠𝗔𝗡𝗗𝗢 𝗗𝗜 𝗨𝗡 𝗗𝗜𝗦𝗧𝗥𝗜𝗕𝗨𝗧𝗢𝗥𝗘 𝗔𝗨𝗧𝗢𝗠𝗔𝗧𝗜𝗖𝗢： 𝗦𝗡𝗔𝗖𝗞 𝗚𝗥𝗔𝗧𝗜𝗦， 𝗔𝗖𝗤𝗨𝗜𝗦𝗧𝗜 𝗗𝗘𝗟𝗜𝗥𝗔𝗡𝗧𝗜 𝗘 𝗖𝗘𝗡𝗧𝗜𝗡𝗔𝗜𝗔 𝗗𝗜 𝗗𝗢𝗟𝗟𝗔𝗥𝗜 𝗜𝗡 𝗣𝗘𝗥𝗗𝗜𝗧𝗔！

Un test condotto nella redazione del Wall Street Journal con un distributore automatico, gestito interamente da un modello di intelligenza artificiale, ha dato risultati... imbarazzanti!

#Anthropic sminuisce l'accaduto!

Ma io ancora non riesco a smettere di ridere! 🤣 🤣🤣

@tecnologia

#tecnologia #ai #ia #claudius #llm

Leggi su ZEUS News: zeusnews.it/n.php?c=31639

Pause Print, Add Hardware, and Enjoy Strength

3D Printing is great, but it is pretty much the worst way to make any given part– except that every other technique you could use to make that part is too slow and/or expensive, making the 3D print the best option. If only the prints were stiffer, stronger, more durable! [JanTech Engineering] feels your plight and has been hacking away with the M601 command to try embedding different sorts of hardware into his prints for up to 10x greater strength, as seen in the video embedded below.

It’s kind of a no-brainer, isn’t it? If the plastic is the weak point, maybe we could reinforce the plastic. Most concrete you see these days has rebar in it, and fiber-reinforced plastic is the only way most people will use resin for structural applications. So, how about FDM? Our printers have that handy M601 “pause print” command built in. By creatively building voids into your parts that you can add stronger materials, you get the best of all possible worlds: the exact 3D printed shape you wanted, plus the stiffness of, say, a pulltruded carbon-fiber rod.

[JanTech] examines several possible inserts, including the aforementioned carbon rods. He takes a second look at urethane foam, which we recently examined, and compares it with less-crushable sand, which might be a good choice when strength-to-weight isn’t an issue. He doesn’t try concrete mix, but we’ve seen that before, too. Various metal shapes are suggested — there are all sorts of brackets and bolts and baubles that can fit into your prints depending on their size — but the carbon rods do come out ahead on strength-to-weight, to nobody’s surprise.

You could do a forged carbon part with a printed mold to get that carbon stiffness, sure, but that’s more work, and you’ve got to handle epoxy resins that some of us have become sensitized to. Carbon rods and tubes are cheap and safer to work with, though be careful cutting them.

Finally, he tries machining custom metal insets with his CNC machine. It’s an interesting technique that’s hugely customizable, but it does require you to have a decent CNC available, and, at that point, you might want to just machine the part. Still, it’s an interesting hybrid technique we haven’t seen before.

Shoving stuff into 3D-printed plastic to make it a better composite object is a great idea and a time-honored tradition. What do you put into your prints? We’d love to know, and so would [Jan]. Leave a comment and let us know.

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hackaday.com/2025/12/21/pause-…