[Ken Shirriff] does some of the most interesting teardowns. This time, he’s looking at a French-built minicomputer called the Mitra 125 MS from around 1980. In particular, it was the computer inside Spacelab, a European lab that could fit in the back of the Space Shuttle.
As you might expect, the computer doesn’t contain a microprocessor. Instead, it is a series of cards and, in this post, [Ken’s] looking at the ALU that allows the computer to perform math operations.
Filtering sawdust out of an airflow is easy until you try to do it with cyclone separation, but the obvious appeal here is of course not spending a fortune on filters. Over the years we have thus seen a lot of DIY takes on this concept alongside commercial offerings. Recently [Ruud] of the [Capturing Dust] YouTube channel gave it a fresh shake with a claimed 99.95% filtering efficiency that outperforms a commercial solution.
As a starting point the commercial and very succinctly named Oneida Air Super Dust Deputy Cyclone Separator was used, which retails for about $179 and claims a 99.9% filtrating rate of fine dust and debris. Based on its design a 3D model was created and printed with an FDM printer.
Initially only about a 98% rate was measured, but after some investigation this appeared to be due to the incoming and exciting airflows interfering. One tweak later to add some separation between the flows and a lot of testing of different configurations a final design was settled on that would seem to be rather quite efficient compared to the commercial option.
Continue reading “Designing A Printable Cyclone Dust Separator For 99.95% Efficiency”
The system uses a Raspberry Pi to control when each valve turns on and for how long. It does this via a custom RS-485 valve master board, whose code and design files are on GitHub. The master board communicates with the Pi over I2C and issues RS-485 commands while controlling the 12V line to the valves. Toggling the 12V supply is a smart move it lets [Vinnie] save power by not keeping the valves energized when idle.
At the valves themselves lives a valve node board (also on the GitHub repo). Each node has a unique address so it knows when its name is called to open or close a valve. The valves are latching solenoids, ideal because they don’t require constant current during the watering cycle. The Valve Nodes also support their own protocol to report state, firmware version, and allow in-situ configuration.
Be sure to head over to [Vinnie]’s project page and check out all the work that went into this great DIY irrigation control system, along with the thoughtful boards and tools he made to help others set it up. This is a welcome addition to the sprinkler-related projects we’ve seen.
The Cheap Yellow Display is a great little module to start a project with, but it wouldn’t necessarily be our first choice for an audio device. That’s because the PWM on the ESP32 isn’t exactly going to put out hi-fi, and the I2C pins needed for the I2S audio protocol aren’t broken out on the CYD board. That didn’t stop [ivans805] AKA [Ill-Town-5623]– he wanted a mod tracker, he had a CYD board, and necessity is the mother of invention.
It isn’t exactly a ground-breaking hack: he’s just tossed a bodge wire to the pin he needs on the ESP32, and run it to the I2S sound module. Still, in this era of endless modules it’s nice to see someone hacking what they have rather than running to AliExpress or somewhere else for a part that has everything the project needs built in.
What really caught our eye when we saw this project on the ESP32 subreddit was the aesthetics. It might be called “Win95-Tracker-CYD” but that interface just screams “Amiga” to us– look at that Boing Ball! Given where MOD files come from, that’s perfect. The UI was made with Lopaka.app, which we haven’t seen before but appears to be a sort of WYSIWYG editor for embedded device interfaces.
While you don’t need an ESP32 to play mod files– the diminutive CH32 can manage the task— there’s no arguing the CYD could make a nice little player. If you actually wanted to push its limits, you might try a 3D engine instead,
Since Sony’s PlayStation 5 console is quite literally an AMD-based gaming PC with a custom mainboard, the only thing that really keeps anyone from just installing another operating system on it is the hypervisor-based firmware. Since in older firmware for the original ‘phat’ PlayStation 5 there exists a hypervisor exploit, this logically means that you can totally run Linux on them, as demonstrated by [Andy Nguyen] with the PS5-linux project on GitHub.
PS5 firmware version 5.x from 2022 seems to have at least partially addressed this particular vulnerability, so this leaves firmware versions 3.x and 4.x supported by PS5-linux for now. Firmware versions 1.x and 2.x also have this vulnerability, but [Andy] hasn’t added support for these yet. As for the prospect of running PS5-linux on 5.x firmware the prospect is less certain, but it’s reckoned that since the OS would then run inside the hypervisor it’d be quite limited in its functionality. Firmware versions 6+ are currently still firmly locked-down.
If you have an original PS5 kicking around with the right firmware version, to use the project you need a 64+ GB USB drive to run from and USB dongles for Wi-Fi/Ethernet. For Bluetooth support you also need a dongle. With the USB drive inserted into the console, on boot it runs the jailbreak exploit and sends the bootloader as payload. If all goes well you should then see the desktop of Ubuntu 26.04 Resolute Raccoon pop up.
It’s arguable how practical this currently is, but since it doesn’t modify the PS5 firmware it’s not permanent at least. Unfortunately Linux doesn’t have drivers for much of the PS5’s hardware, so the available video resolutions are limited, power management features such as standby are not working, and there are currently bugs related to HDMI audio and video output on some monitors.
It’s unfortunate that features like OtherOS (before it got pulled) on the PlayStation 3 or the official Linux for the PlayStation 2 aren’t a thing any more, but this hack offers at least some glimpse of what that could have been like for a modern Sony console.
Although the game Pizza Tycoon – known as Pizza Connection in Europe – probably doesn’t ring a bell for many folk, this 1994 DOS title is special enough for [cowomaly] to write an open source engine to bring it into the modern age as Pizza Legacy. Along the way, some questions popped up, such as how to animate the little cars that you see driving around in the simulated city and how the heck this was done back in the day on a 25 MHz 386 CPU.
Continue reading “How Pizza Tycoon Simulates Traffic On A 25 MHz CPU”
In the ages before convenient global positioning satellites to query for one’s current location military aircraft required dedicated navigators in order to not get lost. This changed with increasing automation, including the arrival of increasingly more sophisticated electromechanical computers, such as the angle computer in the B-52 bomber’s star tracker that [Ken Shirriff] recently had a poke at.
We covered star trackers before, with this devices enabling the automation of celestial navigation. In effect, as long as you have a map of the visible stars and an accurate time source you will never get lost on Earth, or a few kilometers above its surface as the case may be.
The B-52’s Angle Computer is part of the Astro Compass, which is the star tracker device that locks onto a star and outputs a heading that’s accurate to a tenth of a degree, while also allowing for position to be calculated from it. Inside the device a lot of calculations are being performed as explained in the article, though the full equations are quite complex.
Not burdening the navigator of a B-52 with having to ogle stars themselves with an instrument and scribbling down calculations on paper is a good idea, of course. Instead the Angle Computer solves the navigational triangle mechanically, essentially by modelling the celestial sphere with a metal half-sphere. The solving is thus done using this physical representation, involving numerous gears and other parts that are detailed in the article.
In addition to the mechanical components there are of course the motors driving it, feedback mechanisms and ways to interface with the instruments. For the 1950s this was definitely the way to design a computer like this, but of course as semiconductor transistors swept the computing landscape, this marvel of engineering would before long find itself too replaced with a fully digital version.
