Linux Fu: Simple Pipes

In the old days, you had a computer and it did one thing at a time. Literally. You would load your cards or punch tape or whatever and push a button. The computer would read your program, execute it, and spit out the results. Then it would go back to sleep until you fed it some more input.

The problem is computers — especially then — were expensive. And for a typical program, the computer is spending a lot of time waiting for things like the next punched card to show up or the magnetic tape to get to the right position. In those cases, the computer was figuratively tapping its foot waiting for the next event.

Someone smart realized that the computer could be working on something else while it was waiting, so you should feed more than one program in at a time. When program A is waiting for some I/O operation, program B could make some progress. Of course, if program A didn’t do any I/O then program B starved, so we invented preemptive multitasking. In that scheme, program A runs until it can’t run anymore or until a preset time limit occurs, whichever comes first. If time expires, the program is forced to sleep a bit so program B (and other programs) get their turn. This is how virtually all modern computers outside of tiny embedded systems work.

But there is a difference. Most computers now have multiple CPUs and special ways to quickly switch tasks. The desktop I’m writing this on has 12 CPUs and each one can act like two CPUs. So the computer can run up to 12 programs at one time and have 12 more that can replace any of the active 12 very quickly. Of course, the operating system can also flip programs on and off that stack of 24, so you can run a lot more than that, but the switch between the main 12 and the backup 12 is extremely fast.

So the case is stronger than ever for writing your solution using more than one program. There are a lot of benefits. For example, I once took over a program that did a lot of calculations and then spent hours printing out results. I spun off the printing to separate jobs on different printers and cut like 80% of the run time — which was nearly a day when I got started. But even outside of performance, process isolation is like the ultimate encapsulation. Things you do in program A shouldn’t be able to affect program B. Just like we isolate code in modules and objects, we can go further and isolate them in processes.

Doubled-Edged Sword

But that’s also a problem. Presumably, if you want to have two programs cooperate, they need to affect each other in some way. You could just use a file to talk between them but that’s notoriously inefficient. So operating systems like Linux provide IPC — interprocess communications. Just like you make some parts of an object public, you can expose certain things in your program to other programs.

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Tech In Plain Sight: Tough As Nails

When you think of machines you see around you every day, you probably think about your car, computer, or household appliances. However, the world is full of simple machines. One simple machine in particular, the inclined plane, shows up a lot. For example, think of the humble nail. If you are a woodworker or even a homeowner you probably have bags of them. They certainly are all around you if you are indoors and maybe even if you are outdoors right now. Nails have been the fastener of choice for a very long time and they are a form of a wedge which is a type of inclined plane.

What else can you say about nails? Turns out, there is a lot to know. Like other fasteners, there are nails for very specific purposes. There are even nails with two heads and — no kidding — nails with two points. Exactly what kind of nail you need depends on what you are doing and what’s important to you.

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Run Your Own Server For Fun (and Zero Profit)

It seems there’s a service for everything, but sometimes you simply learn more by doing it yourself. If you haven’t enjoyed the somewhat anachronistic pleasures of running your own server and hosting your own darn website, well, today you’re in luck!

Yes, we’re going to take an old computer of some sort and turn it into a web server for hosting all of your projects at home. You could just as easily use a Raspberry Pi –even a Zero W would work — or really anything that’ll run Linux, but be aware that not all computing platforms are created equally as we’ll discuss shortly.

Yes, we’re going to roll our own in this article series. There are a lot of moving parts, so we’re going to have to cover a lot of material. Don’t worry- it’s not incredibly complicated. And you don’t have to do things the way we say. There’s flexibility at every turn, and you’re encouraged to forge your own path. That’s part of the fun!

Note: For the sake of space we’re going to skip over some of the most basic details such as installing Linux and focus on those that have the greatest impact on the project. This article gives a high level overview of what it takes to host your project website at home. It intentionally glosses over the deeper details and makes some necessary assumptions.

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Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The Really Tall Keycaps

About a month ago, [Unexpected Maker] finished their TinyS3, an ESP32-S3 development board. Since the chip supports both true USB and Bluetooth, [deʃhipu] wondered how well it would work in a keyboard.

Thus, the Vegemite Sandwich was made, perhaps while [deʃhipu] was dreaming of traveling in a fried-out Kombi. But really, it was named so because [Unexpected Maker] hails from Australia.

This is [deʃhipu]’s first time using switch sockets, which is (as far as we know) the only choice when it comes to hot-swappable Kailh chocs. We’ll be watching this one with hungry eyes.

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The Tasmanian Tiger’s Comeback Tour, Powered By Science

Scientists estimate that approximately 900 species have gone extinct in the last five centuries alone, to say nothing of the thousands or millions that vanished from life in the billions of years before that.

Conventional wisdom states that once an animal has gone extinct, it’s gone forever. However, a team from the University of Melbourne hopes to change all that, with their new project aiming to bring the Tasmanian Tiger back to life.
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Hackaday Links: March 13, 2022

As Russia’s war on Ukraine drags on, its knock-on effects are being felt far beyond the eastern Europe theater. And perhaps nowhere is this more acutely felt than in the space launch industry, seeing that at least until recently, Russia was pretty much everyone’s go-to ride to orbit. All that has changed now, at least temporarily, and has expanded to include halting sales of rocket engines used in other nations’ launch vehicles. Specifically, Roscosmos has put an end to exports of the RD-180 engine used in the US Atlas V launch vehicle, along with the RD-181 thrusters found in the Antares rocket. The loss of these engines may be more symbolic than practical, at least for the RD-180 — United Launch Alliance stopped selling launches on Atlas V back last year, and had secured the engines it needed for the 29 flights it has booked by that April. Still, there’s some irony that the Atlas V, which started life as an ICBM aimed at the USSR in the 1950s, has lost its Russian-made engines.

Bad news for Jan Mrázek’s popular open-source parametric search utility which made JLCPCB’s component library easier to use. We wrote about it back in 2020, and things seemed to be going fine up until this week, when Jan got a take-down request for his service. When we first heard about this, we checked the application’s web page, which bore a big red banner that included what were apparently unpleasant accusations Jan had received, including the words “reptile” and “parasitic.” The banner is still there, but the text has changed to a more hopeful tone, noting that LCSC, the component supplier for JLC’s assembly service, objected to the way Jan was pulling component data, and that they are now working together on something that everyone can be happy with. Here’s hoping that the service is back in action again soon.

Good news, everyone: Epson is getting into the 3D printer business. Eager to add a dimension to the planar printing world they’ve mostly worked in, they’ve announced that they’ll be launching a direct-extrusion printer sometime soon. Aimed at the industrial market, the printer will use a “flat screw extruder,” which is supposed to be similar to what the company uses on its injection molding machines. We sure didn’t know Epson was in the injection molding market, so it’ll be interesting to see if expertise there results in innovation in 3D printing, especially if it trickles down to the consumer printing market. Just as long as they don’t try to DRM the pellets, of course.

You can’t judge a book by its cover, but it turns out that there’s a lot you can tell about a person’s genetics just by looking at their face. At least that’s according to an AI startup called FDNA, which makes an app called “Face2Gene” that the company claims can identify 300 genetic disorders by analyzing photos of someone’s face. Some genetic disorders, like Down Syndrome, leave easily recognizable facial features, but some changes are far more subtle and hard to recognize. We had heard of cases where photos of toddlers posted on social media were used to diagnose retinoblastoma, a rare cancer of the retina. But this is on another level entirely.

And finally, working in an Amazon warehouse has got to be a tough gig, and if some of the stories are to be believed, it borders on being a horror show. But one Amazonian recently shared a video that showed what it’s like to get trapped by his robotic coworkers. The warehouse employee somehow managed to get stuck in a maze created by Amazon’s pods, which are stacks of shelves that hold merchandise and are moved around the warehouse floor by what amounts to robotic pallet jacks. Apparently, the robots know enough to not collide with their meat-based colleagues, but not enough to not box them in. To be fair, the human eventually found a way out, but it was a long search and it seems like another pod could have moved into position to block the exit at any time. You could see it as a scary example of human-robot interaction gone awry, but we prefer to look at it as the robots giving their friend a little unscheduled break away from the prying eyes of his supervisor.

The Metal 3D Printing Hack Chat Brings The Heat

At this point, it’s safe to say the novelty of desktop 3D printing has worn off. The community has largely come to terms with the limitations of extruded plastics, and while we still vehemently believe that it’s a transformative technology, we’ll admit there aren’t too many applications where a $200 USD printer squirting out PLA is truly the best tool for the job.

But rather than looking at today’s consumer 3D printer market as the end of the line, what if it’s just the beginning? With the problems of slicing, motion control, and extrusion more or less solved when it comes to machines that print in plastic, is it finally time to turn our attention to the unique problems inherent in building affordable metal printers? Agustin Cruz certainly thinks so, which is why he took to the Hack Chat this week to talk about his personal vision for an open source 3D printer that can turn powdered metals into solid objects by way of a carefully controlled electron beam.

To be clear, Agustin isn’t suggesting you toss out your Creality anytime soon. Metal 3D printing will always be a niche within a niche, but for applications where even advanced engineering plastics like PEI and PEEK simply won’t do, he argues the community needs to have a cheap and accessible option. Especially for developing and low income countries where traditional manufacturing may be difficult. The machine he’s been working on wouldn’t be outside the capabilities of an individual to build and operate, but at least for right now the primary target is hospitals, colleges, and small companies.

The Chat was full of technical questions about Agustin’s design, and he wasn’t shy about tackling them. Some wondered why he decided to sinter the metal powder with an electron gun when solid-state lasers are cheap, easily available, and relatively straightforward to work with. But while the laser might seem like the easier solution on the surface, Agustin points out that using a magnetically focused electron beam gives his printer some unique capabilities.

For example, he can easily defocus the beam and pass it over the entire build plate to pre-heat the powder. The steerable beam doesn’t require mirrors either, which not only reduces the weight and complexity of the machine, but in theory should allow for faster print speeds. The beam can be moved in the X/Y dimensions with an accuracy of 0.01 mm, and while the beam diameter is currently a respectable 0.5 mm, Agustin says he’s working on bringing that down to 0.1 mm for high detail work. The temperature at the focal point of the beam is between 1,400 and 1,500 °C, which he notes is not only hot enough to melt the powdered metal, but can also weld stainless steel.

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