Ask Hackaday: Do We Need A 21st Century Calculator?

May 14, 2026 by Al Williams 77 Comments

The HP-41C analog on my phone gives the right answer.

Three resistors in parallel: 4.7 k,Ω 22 kΩ, and 3.3 kΩ. Quick! What’s the equivalent value? You can estimate it, of course, but if you want the actual 1.8 kΩ (approximately) answer, you probably reached for some kind of calculating aid. I have two slide rules on my desk, and plenty more a few steps away, but I don’t use them much, honestly. I have a very old HP-41C — arguably the best calculator ever made — but I am usually afraid to use it as it is almost 50 years old and difficult to repair. I also have an HP-28S on my desk, a replica HP-41C, and a few others in desk drawers. There are also dozens of calculators on my desktop computer, my phone –including the official HP Prime app — and the web browser.

I often see newer calculators from HP, like the Prime G2, or “new” HP-like calculators like the ones from SwissMicros, and think I should pick one up. Well, technically, HP licensed their calculators to Moravia, so even a “real” HP calculator isn’t from HP anymore. But, in the end, I always realize that my need for a physical calculator is so diminished that I can’t justify buying anything new, and I can barely even spring for a $10 one at the thrift store unless it is a real collectible.

Mind you, I’m not talking about RPN versus algebraic. I could say the same thing for TI, Casio, or Sharp calculators. I just don’t know why I need one anymore, even though I still, for some strange reason, want them.

The Prime seems impressive, if I could ever find time to finish reading the manual.

For the record, I did use an HP-41C to check the resistor math, but it was in the form of an app on my phone, not a real calculator. On the same computer I’m writing this on, I have HP-41C emulators, the Prime emulator, and a bunch of other calculators. Yet I still pick up my phone and use the familiar key layout of the HP-41C. I don’t know why. The replica 41C, unfortunately, has a landscape-oriented keyboard, so while I like it, it doesn’t satisfy my finger’s muscle memory.

Which leads to this Ask Hackaday. Do you use a calculator? Why? If you don’t, do you use a fake calculator on your phone or computer? Or do you just send your math to Google or Wolfram? I suspect some of the answer will be generational. I was in high school before calculators started showing up in schools, but they took over quickly.

There is something satisfying about having a purpose-built device to do your math. No long boot sequence. No switching apps. No messages coming in while you are typing in numbers. For the ultimate convenience, you could wear it on your wrist. The Apollo mission that docked with a Russian spacecraft carried an HP-65, and nine early Space Shuttle missions used an HP-41C. But even astronauts now don’t have a standard-issue calculator. Pilots sometimes use electronic E6Bs, but many still use the mechanical version.

Of course, I do collect slide rules, so maybe I just need to accept that calculators are yet another tech relic to collect. But someone is still buying them. I’d like to be one of them.

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Copy Or Redesign?

May 9, 2026 by Elliot Williams 5 Comments

We got asked a great question in the mailbag segment on the Podcast this week: are there hacks that we have read about on Hackaday that we use in our everyday life? The answer was absolutely yes, and I loved Tom’s take it often goes the other way – he sees a hack, tests it out, and then writes it up.

But I started looking around the office and I found more examples of projects that were absolutely inspired by projects I had seen on Hackaday, yet weren’t the same. I made a DIY mechanical keyboard because I saw someone else do it. There are a few home-made battery packs that I probably wouldn’t have attempted without having read about someone doing the same thing. I riffed on [Ted Yapo]’s Tritiled project, making a slightly inferior, but workable knockoff, and they’ve been glowing for many years now.

That got me to thinking about reproducing a project versus taking inspiration from it, and though I enjoy both, I’m find myself most often in the “inspiration” mode. I just can’t leave well enough alone, even when I’m fundamentally copying someone. NIH syndrome? Expediency? Probably both, and sometimes with a dose of hubris or feature creep.

Looking back at [Ted]’s TritiLED, though, I found some great examples in both the rebuild and redesign modes on Hackaday.io. [schlion]’s Making Ted Yapo’s TritiLED couldn’t be a clearer example of the former, and it’s great to look over his shoulder and appreciate all the lessons he learned along the way. [Stephan Walter]’s Yet another ultra low power LED is inspired by [Christoph Tack]’s Ultra low power LED, which is in turn inspired by [Ted]’s project, like a conceptual grandchild.

In a way, I look at this like with music: sometimes you play the notes the way they were written down, and sometimes you riff on someone else’s theme. Both are equally valid, and both owe a debt to the upstream source. Is Hackaday the hackers’ jazz club? And which of these modes do you find yourself working in most?

Peripherals Hacks

May 2, 2026 by Elliot Williams 10 Comments

Custom peripheral projects are among the most rewarding. Especially if you’re like me and you sit at the computer eight hours per day, anything that you can use on a daily basis is super satisfying. This topic of DIY peripherals came up on the podcast while chatting with Kristina, who is no stranger to odd inputs herself.

We were talking about a trackball that had been modified to read twisting gestures, by a clever hijacking of the twin mouse sensors inside. If you do a lot of 3D modeling, you can absolutely get by with just a mouse and shift-ctrl-alt as modifiers, but it’s so much more immediate to use a dedicated 3D input device. (I’ve got an ancient serial Space Mouse just under my left hand as I type this.)

My old favorite, which I haven’t used in ages, is the guts of a 5” hard-drive platter stack that I turned into a scroll wheel. Unfortunately, I don’t have space for it on my desk anymore, but it was just so pleasing to scroll through a document with something that had some real chonky momentum to it.

And it’s easier than ever to make your own. The classic blocky macropad is a great introduction, but as long as you’re doing the design yourself, why not extend it, or at least make it fit your hand? Or take your flights of fancy even further away from the mainstream. Consider the Bluetooth mouse ring, for instance.

Point is, the software side of almost any peripheral device you can imagine is sorted out already, and interfacing with the hardware is equally simple. Peripheral hacks have such a low barrier to entry, but afford so many creative hardware possibilities. And nothing says “Jedi” like building your own lightsaber.

Ask Hackaday: Do You Need A Tablet?

April 29, 2026 by Al Williams 92 Comments

There’s an old saying that the happiest days of a boat owner’s life are the day they buy the boat, and the day they sell it. For me, the happiest days of an Android tablet owner’s life are the day they buy a new one, and the day they buy a newer one. For some reason, I always buy tablets with great expectations, get them set up, and then promptly lose them in a pile on my desk, not to be seen again. Then a shiny new tablet gets my attention in a year or so, and the cycle repeats.

You might be thinking that I just buy cheap junk tablets. It is true that I have. But I have also bought new Galaxy and Asus tablets with the same result. Admittedly, I have owned several Surface Laptops and Pros, and I do use them. But I can’t remember the last time I have used one without the keyboard. They aren’t really tablets — they are just laptops that can also be heavy, awkward tablets.

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Tool Embodiment And The Dead Trackball

April 18, 2026 by Elliot Williams 42 Comments

There is a currently ongoing debate in the neuropsychology world about how we relate to the tools that we use. The theory of “tool embodiment” says that when we use some tools frequently enough, our brain recognizes them similarly to how it recognizes our own hands, for instance. There is evidence and counter-evidence from experiments with prosthetics, trash-grabber arms, and rubber dummy arms, just to name a few. It’s fair to say the jury is still out.

All I know is that today my trackball broke, and using a normal gaming mouse to edit the podcast was torture. It would be an exaggeration to say that I felt like I’d lost a hand, but I have so much motor memory apparently built up in my use of the trackball that switching over to another tool to undertake the exact same series of hundreds of small audio edits – mostly compensating for the audio delay across continents, but also silencing coughs and background noises – took an extra hour.

Anyone who has switched from one keyboard to another, or heck even from emacs to vim, knows what I experienced. My body just knows how to flick my wrist to make the cursor on the screen move over to the beginning of that “umm”. It’s not like I don’t conceptually know how to use a mouse either, and it does exactly the same job. But the mouse wasn’t my tool for this application. And saying that out loud makes it almost sound like I’m bordering on embodying my trackball.

I probably should have taken the trackball apart and replaced the bad tact switch on the left-click – that would have taken maybe twenty minutes – but I completely underestimated how integral the tool had become to the work. Anyway, as I write this, tomorrow is Saturday and I’ll have time to fix it. But today, I learned something pretty neat about myself in the process, even if I don’t think my single datapoint is going to rock the academic psych world.

Making The Case Against Markdown

April 5, 2026 by Maya Posch 55 Comments

For some reason, Markdown has not just become the format of choice for giving READMEs in GitHub repositories some flair, but also for writing entire websites and documents. In a recent rant, [Burak Güngör] covers all the ways in which Markdown is a good idea as a basic document formatting concept and how its implementation is absolutely atrocious.

Even without straying into the minefields helpfully provided by other Markdown dialects beyond CommonMark, there is already plenty here to indulge in. The very idea of Markdown as a ‘simple text formatting syntax’ breaks down the moment you look at the available formatting styles and how they translate into HTML. Worse, the sheer complexity of parsing Markdown makes it vulnerable to a regular expression denial-of-service (ReDoS) attack.

This is where the question arises of whether Markdown is truly a text formatting aid or trying to be a programming language that just happens to usually spit out HTML documents, as, at some point, you’re basically writing something that approaches a regular expressions engine in its nightmarish implications.

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Re-Learning How To Run

April 5, 2026 by Elliot Williams 48 Comments

As I write this, four astronauts are on their way around the moon for the first time in 50 years. A lot us have asked ourselves just exactly why you’d send people out that far when the environment is so hostile and we have increasingly competent robots that could do the jobs in their place. If anything, that’s even more true now than it was back in the day of the Apollo program, when the remote operations capability was a lot more constrained. But having people, potentially in the near future, on the lunar surface remains qualitatively different.

I was recently re-watching some of the footage from Apollo 16 when the astronauts were driving around in the Lunar Roving Vehicle, and the discussions that they’re having about the lunar geology that they can see for the first time with their own eyes is very convincing. Having people in situ tightens the loop of “hey, that’s interesting”, “let’s take a closer look”, and “I wonder what that means” in a way that minutes or hours of transmission time, and sterile observation of photos on a computer monitor just break. In comparison, our Mars rovers move excruciatingly slowly, the data comes back through a very thin pipe, and it takes months or years to analyze.

Of course, there is danger to human life; it’s a lot more expensive to get people safely to, and importantly back from, the moon than it would be with a disposable robot. Comparison with the Mars rovers is also unfair because travel to Mars is another scale entirely. Even if it does make sense to send humans for exploration on the moon, it may not make sense to do the same on the red planet, in the near future or ever. Given all that, I’m stoked that we can see through the robots eyes, but if all else were equal, I’m sure that we’d learn more from human explorers.

While in a lot of ways the Artemis I and now the Artemis II missions are underwhelming in comparison to the many “firsts” of Apollo, I absolutely appreciate them for what they are: a shakedown trial of a set of technologies and practices that we used to grasp, but which have atrophied over the last five decades. If a new generation of scientists is to put feet onto regolith, we need to learn to walk before they can run, or rover. In that spirit, I’ll be crossing my fingers for the future of manned spaceflight over the next week and a half.