Curated

76 Articles

Hackaday’s finest original content articles curated by the Hackaday editors

A map of the lower 48 US States with an overlay of various colorful bubbles indicating data center developments, whether proposed, contested, under construction, or operational. There are a lot of bubbles! Hawaii isn't pictured, but looks to have one project currently, but nothing in Alaska for now.

Who’s Building That Data Center?

July 21, 2026 by 55 Comments

One of the biggest “David versus Goliath” stories in tech right now is the towns beset by AI data center projects they may or may not have asked for. Powered By Who is tracking data center development in the US on this convenient map.

Currently, there are over 2,100 data centers being tracked by the project ranging from proposals to sites fully up-and-running. While you have to build bypasses data centers to keep the internet running (which we’re partial to here at Hackaday), there are certainly questions around the amount of power and water consumed by these sites, the emissions they’re sending into the surrounding community, and who exactly is reaping the benefits.

Whether you’re pro, against, or ambivalent about the proliferation of “AI” data centers, the map offers an engaging way to look at what projects are happening around the nation, especially when you start looking at clusters and how that interacts with the power generation and political makeup in a region. It’s particularly interesting how only three states account for roughly 70% of all the projects. Let us know if there’s a similar tracker in your area if you’re from one of the other parts of the globe!

Looking past the debate, there’s a lot of interesting engineering involved in keeping these data centers cool, although there are questions about where that heat ends up going. DC distribution inside the site, underwater data centers, and even putting them in space are some of the solutions for keeping the cooling loads tamed.

Postal IRCs Are Almost A Thing Of The Past

July 21, 2026 by 18 Comments

Have you ever found out that something you remember from your youth is now gone, and you didn’t even notice? If you are a certain age, you might feel that way when I deliver the news: You haven’t been able to buy International Reply Coupons (IRCs) at a US Post Office since early 2013. By the end of 2026, you won’t be able to buy them anywhere. The age of the IRC is over.

What’s an IRC?

An IRC from 1978 (public domain).

If that didn’t mean anything to you, you might be too young to remember, or maybe you just weren’t into shortwave listening or ham radio. Although there were other reasons to get IRCs, a radio hobby is the most likely reason a Hackday reader would have bought an IRC.

For radio purposes, here’s the problem. You’ve worked on your station for months, and one winter night, you finally pull in that rare station from Luxembourg. They’ll send you a QSL card to verify that you heard them. You only have to send them a letter telling them what time you heard them, what frequency, and some details about the program you heard. But they probably don’t want to pay the postage required to send hundreds or thousands of cards overseas.

While this is a radio-specific problem, you might find the same issue with pen pals or when trying to buy things from an overseas company.

SASE

If everyone were in the same country, the solution would be easy. Take a stamp, put it on an envelope that has your address on it, and stuff it in with the letter. Or, you could just drop a stamp or two in the letter you sent.

The problem is, US postage won’t help Radio Luxembourg. On the other hand, the effort required for you to buy postage that works in Luxembourg would have been a nightmare.

Enter the UPU

The Universal Postal Union is a UN agency that is effectively an association of post offices in 192 countries. Their charter is to facilitate mailing things worldwide.

The IRCs date back to 1906. The idea is you buy an IRC at your post office. You send it to Radio Luxembourg, or wherever. There, the mail person at the radio station could go to their post office and trade the coupon for enough local postage to send a surface letter worldwide.

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Launching Rockets Is Hard, Bringing Them Back Is Harder

July 20, 2026 by 19 Comments

Since the first V2 rocket sailed above the Kármán line back in 1944 and right up until the modern era, the trajectory of most space-bound rockets was more or less the same: after expending their propellants they would either crash into some desolate steppe or plunge into the ocean. In either event, the rocket was disposable. The important bit up top might go on to explore the stars or send a human crew off on their mission, but the booster rocket that lifted the spacecraft out of the atmosphere was always going to be sacrificed for the cause.

But in the 1970s NASA had a wild idea: what if we didn’t smash a brand-new rocket valued at millions of dollars into the ocean every time we wanted to put something in orbit? Instead, they would build a hybrid space vehicle that blended the vertical takeoff and raw power of a rocket with the capabilities of an airplane, allowing it and whatever it was carrying to make a gentle runway landing at the end of its mission. As such, the Space Shuttle was born.

With the benefit of hindsight, we now know the Shuttle wasn’t quite the spaceflight revolution that NASA had hoped for. The age of reusable rockets didn’t truly begin until 2015, when SpaceX landed the first stage of their Falcon 9. To date they’ve repeated the feat nearly 600 times, all the while increasing the reliability and speed of their operations. Today the Falcon 9 is the most prolific launch vehicle in history, and nearly every other rocket in active development is being designed to include some element of reusability.

Most recently, China demonstrated that they could recover their Long March 10B rocket by gently bringing it down into what amounts to a giant butterfly net. While it might seem a bit quaint compared to rockets that land on their tails like something out of a 1950s sci-fi movie, the idea offers considerable promise.

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UDP Broadcasting And The Joys Of IPv4 Subnetting

July 14, 2026 by 35 Comments

In the previous installment on UDP broadcasting and service discovery, the basics of both were explored, including an implementation in the form of NyanSD and its protocol. Contained in the comment section was a very good demonstration of why one of the most exciting aspects of software development is the opportunity to share your latest creations with other people. This being the ability to get solid feedback on all the points – including any potential boneheaded omissions – that you really should address, whether intentional or accidental.

The most pertinent point raised was definitely that of broadcast addresses and IPv4 subnets, with the latter topic especially being something that the sysadmins at the office would talk about all the time, but which us software developers were always happy to ignore as something that didn’t concern us. Turns out the joke was on me and everyone else – like our esteemed readers – who thought that they could escape the fascinating world of subnets, as today we’ll take an in-depth look at what subnets are and how they are relevant to the world of UDP network discovery.

I somewhat alluded in the first article to the topic of ‘which broadcast address to use’ as being somewhat of a rough topic to figure out, which is clearly why I just stuck to a blatantly ‘works for me’ /24 subnet that usually will work on networks, until it does not.

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The Death Of Physical Media And The Real Challenges To Software Archiving

July 13, 2026 by 30 Comments

Along with the many displays of outrage, gnashing of teeth and other displays of profound grief at the recent news that Sony will no longer manufacture physical game discs come 2028, we have also heard some voices pipe up with a variety of statements, such as that this decision makes game archiving basically impossible. Of course, the truth of the matter is that software archiving in general has become much harder already over the past decades, while game consoles are just late to the archiving-hostile party.

As an example, one merely has to contrast Sony’s PlayStation with e.g. the Valve Steam store and software by juggernauts like Adobe and Autodesk. Here the former moved after the Creative Suite (CS6) series of Photoshop and other tools fully over to the Creative Cloud (CC) subscription model, where DRM and constant rental software renewals are in order. Unlike that disc copy of CS6 Master Collection that will stay good practically forever, there’s nothing really to archive with Adobe’s CC software.

Similarly, with digital game downloads and their constant patches now put inside a heavily encrypted environment that relies on a special launcher, preserving video games has been turned into into a virtual nightmare for many years now.

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A Brief History Of The Crazy Old 7-Segment Display

July 9, 2026 by 17 Comments

How old is the seven-segment display? Surely it is a product of the 1970s. After all, calculators started showing up, and the height of junior high humor was plugging 7734 into your calculator and showing it to someone upside down. Of course, for it to go mainstream, maybe they really originated in the 1960s, but no earlier than that, right? Actually, no. Sure, the LED seven-segment display had to wait for LEDs. But the actual idea is much older than that.

The concept of building numbers from a small set of reusable segments predates LED displays by decades. In fact, the basic idea appears in patents from the early 1900s and may have roots in even older mechanical signs and printing techniques.

The history isn’t entirely straightforward. Unlike vacuum tubes or transistors, segmented displays evolved gradually through a series of practical ideas rather than one defining invention.

Blacking out the Eight

While looking into the history of segmented displays, I was reminded of something I’d seen years ago in retail stores: reusable price tags printed with rows of eights.

Rather than printing every possible price, the clerk simply used a marker to black out portions of each figure, transforming an 8 into whatever digit was needed. Cover a few strokes, and the eight becomes a three. Remove a different set, and it becomes a zero or a five. It was, in essence, a manual segmented display.

Finding the exact origin of these price tags is akin to finding out where Romans bought sponges. They were inexpensive commercial supplies, not the sort of products that historians carefully documented. My recollection is from the middle of the twentieth century, but the underlying concept is almost certainly older.

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Art of 3D printer in the middle of printing a Hackaday Jolly Wrencher logo

Is Now The Time For Volumetric 3D Printing?

July 7, 2026 by 29 Comments

Of all innovations adopted by the maker community within the past couple of decades, one stands among the rest on top for anything regarding manufacturing. It goes without saying here at Hackaday how many projects have been reliant on using the technology to turn their ideas into reality. 3D printing has been a maker community invention and, in return, has expanded this hacky community into something that anyone with an imagination can get into. It also goes without saying that the layer-based tech imposes limits on what we can actually create: think overhangs and layer adhesion. However, there’s a possibility that a recent offshoot of this scrappy community has the power to eliminate some of these faults.

Volumetric additive manufacturing (VAM) is a young technology that has a similar start to many new tech toys, including the original SLA of the first 3D printers. That is expensive and completely stuck in the laboratory… Fortunately, that’s not where 3D printing as a whole stayed, as the RepRap project managed to bring the obscure technology to the hobbyists’ main stage. An entire group of people formed and spent countless hours until the useless pieces of poorly extruded plastic could form parts impossible to make with anything else. A cool quirk of history is that it likes to repeat: examples spur recreation, and this appears to be happening with the technology found within VAM printing.

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