FLOSS Weekly Episode 763: Fedora Fixes Everything

December 27, 2023 by 18 Comments

This week Jonathan Bennett and Dan Lynch talk once again with Neal Gompa of Fedora, CentOS, openSUSE and more. This time the focus is Fedora, with sprinklings of Immutable Linux, KDE 6, and the new Linux stack of Pipewire, Portals, and Wayland. Neal gives us a rundown of what exactly makes Fedora Atomic so interesting, and why you probably don’t want it running on your desktop. But in a computer lab, or on a public machine? Fedora Atomic might be exactly what you need.

Up next there’s Pipewire, the userspace sound server that replaces Pulseaudio and Jack. Should we think of Pipewire as Jack 3.0? And what’s the secret to getting really reliable low-latency performance for Pipewire in Fedora? It might not be what you expect.

There’s a popular rant online, that Wayland breaks everything. And for years, that’s been a relatively accurate statement, in that Wayland hasn’t been ready for prime-time. Fedora 40 has gone all in on the belief that Wayland’s time has come, with KDE and Gnome no longer having an X11 native option. It’s Wayland all the way. And as one that has run Rawhide, I can say that the future there is bright. Literally, if you have an HDR capable monitor.

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Modern Control Of A Logic Analyzer

December 27, 2023 by 8 Comments

When you think of a logic analyzer today, you might think of a little USB probe that can measure a few signals and decoding for various serial buses. But actual logic analyzers were high-speed multichannel hardware with sophisticated ways to clock and trigger. [Tom] picked up an HP1670G on the surplus market and was impressed that it could sample 136 channels at 500 MHz. The circa-2000 machine has a front panel, but if you really wanted to use it, you wanted to use an X terminal. [Tom] shows us how that works with modern Linux software.

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Several Raspberry Pi Picos connected to each other

Raspberry Pi Pico Parallel Mandelbrot Computation

December 27, 2023 by 11 Comments

The Mandelbrot set is — when visualized with some colors — an interesting shape with infinite detail. While the patterns are immediately obvious to the human eye, anyone who’s run one can tell you that they’re pretty computationally expensive to produce. Fortunately, as with many things in graphics, rendering the Mandelbrot set can be easily parallelized.

That’s what [rak277] and [ir93] demonstrate in their RP2040-based finals project. Computron, as they call it, is a network of Raspberry Pi Picos that work together to compute a visualization of the Mandelbrot set and show it on a VGA display. The Computron is made of two or more “math units” and one “projection unit”. The math units communicate over a shared I²C bus with the projection unit to first divide the workload and then compute their share of the work.

This project shows both the strengths and limitations of parallel computation. It makes use of multiple math units on a highly parallelizable workload, but as more math units are added there are diminishing performance gains due to the increased communications load on the network, which [rak277] and [ir93] suspect to be the current bottleneck in the Computron.

If you’re fresh out of Pi Picos, and don’t mind waiting awhile, you could always crank out a Mandelbrot set on your trusty Atari 800 in BASIC.

Beyond The Basics: Exploring More Exotic Scope Trigger Modes

December 27, 2023 by 2 Comments

Last time, we looked at some powerful trigger modes found on many modern scopes, including the Rigol DHO900 series we used as an example. Those triggers were mostly digital or, at least, threshold-based. This time, we’ll look at some more advanced analog triggers as well as a powerful digital trigger that can catch setup and hold violations. You can find the Raspberry Pi code to create the test waveforms online.

In addition to software, you’ll need to add some simple components to generate the analog waveform. In particular, pin 21 of the Pi connects to  2uF capacitor through a 10K resistor. The other side of the capacitor connects to ground. In addition, pin 22 connects directly to the capacitor, bypassing the 10K resistor. This allows us to discharge the capacitor quickly. The exact values are not especially important.

Runt Triggers

A runt pulse is one that doesn’t have the same voltage magnitude as surrounding pulses. Sometimes, this is due to a bus contention, for example. Imagine if you have some square waves that go from 0 to 5V. But, every so often, one pulse doesn’t make it to 5V. Instead, it stops at 3V.

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Paged Out! Releases Long-Awaited Third Issue

December 27, 2023 by 4 Comments

We’re happy to pass along word that Paged Out! has finally released Issue #3. This online zine covers a wide array of technical topics, from software development to hardware hacking, computer security, and electronics.

It’s distributed as a PDF, and is notable for its somewhat experimental format that limits each article to a single page. The first two issues were released back in 2019, but between a global pandemic and some administrative shuffling, progress on the current release was slowed considerably.

Among the 50 articles that make up the third Paged Out! there are a number of pieces focusing on hardware, such as the serial communications “cheat sheet” from [Jay Greco], and a pair of articles covering the state-of-the-art in custom keyboards. But overall the zine does lean hard into programming topics, and is probably best suited for those with an interest in software development and infosec.

Still, the line between hardware and software is getting blurrier all the time, so we’re sure you can find something in Paged Out! that should interest you no matter which side of the fence you’re on. Here’s hoping the time between releases can be reduced a bit for Issue #4.

Liftoff! The Origin Of The Countdown

December 27, 2023 by 18 Comments

What’s the most thrilling part of rocketry? Well, the liftoff, naturally. But what about the sweet anticipation in those tense moments leading up to liftoff? In other words, the countdown. Where did it come from?

Far from being simply a dramatic device, the countdown clock serves a definite purpose — it lets the technicians and the astronauts synchronize their actions during the launch sequence. But where did the countdown  — those famed ten seconds of here we go! that seem to mark the point of no return — come from? Doesn’t it all seem a little theatrical for scientists?

It may surprise you to learn that neither technicians nor astronauts conceived of the countdown. In their book, “Lunar Landings and Rocket Fever: Rediscovering Woman in the Moon”, media scholars Tom Gunning and Katharina Loew reveal that a little-known Fritz Lang movie called Woman In the Moon both “predicted the future of rocketry” and “played an effective role in its early development”.

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Veteran SpaceX Booster Lost Due To Rough Seas

December 27, 2023 by 44 Comments

With the notable exception of the now retired Space Shuttle orbiters, essentially every object humanity ever shot into space has been single-use only. But since December of 2015, SpaceX has been landing and refurbishing their Falcon 9 boosters, with the end goal of operating their rockets more like cargo aircraft. Today, while it might go unnoticed to those who aren’t closely following the space industry, the bulk of the company’s launches are performed with boosters that have already completed multiple flights.

This reuse campaign has been so successful these last few years that the recent announcement the company had lost B1058 (Nitter) came as quite a surprise. The 41 meter (134 foot) tall booster had just completed its 19th flight on December 23rd, and had made what appeared to be a perfect landing on the drone ship Just Read the Instructions. But sometime after the live stream ended, SpaceX says high winds and powerful waves caused the booster to topple over.

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