The Many-Sprites Interpretation of Amiga Mechanics

The invention of sprites triggered a major shift in video game design, enabling games with independent moving objects and richer graphics despite the limitations of early video gaming hardware. As a result, hardware design was specifically built to manipulate sprites, and generally as new generations of hardware were produced the number of sprites a system could produce went up. But [Coding Secrets], who published games for the Commodore Amiga, used an interesting method to get this system to produce far more sprites at a single time than the hardware claimed to support.

This hack is demonstrated with [Coding Secrets]’s first published game on the Amiga, Leander. Normally the Amiga can only display up to eight sprites at once, but there is a coprocessor in the computer that allows for re-drawing sprites in different areas of the screen. It can wait for certain vertical and horizontal line positions and then execute certain instructions. This doesn’t allow unlimited sprites to be displayed, but as long as only eight are displayed on any given line the effect is similar. [Coding Secrets] used this trick to display the information bar with sprites, as well as many backgrounds, all simultaneously with the characters and enemies we’d normally recognize as sprites.

Of course, using built-in hardware to do something the computer was designed to do isn’t necessarily a hack, but it does demonstrate how intimate knowledge of the system could result in a much more in-depth and immersive experience even on hardware that was otherwise limited. It also wasn’t free to use this coprocessor; it stole processing time away from other tasks the game might otherwise have to perform, so it did take finesse as well. We’ve seen similar programming feats in other gaming projects like this one which gets Tetris running with only 1000 lines of code.

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Thanks to [Keith] for the tip!

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Virus-Based Thermoresponsive Separation of Rare-Earth Elements

Although rare-earth elements (REEs) are not very rare, their recovery and purification is very cumbersome, with no significant concentrations that would help with mining. This does contribute to limiting their availability, but there might be more efficient ways to recover these REEs. One such method involves the use of a bacteriophage that has been genetically modified to bind to specific REEs and release them based on thermal conditions.

The primary research article in Nano Letters is sadly paywalled, but the supporting information PDF gives some details. We can also look at the preceding article (full PDF) by [Inseok Chae] et al. in Nano Letters from 2024, in which they cover the binding part using a lanthanide-binding peptide (LBP) that was adapted from Methylobacterium extorquens.

With the new research an elastin-like peptide (ELP) was added that has thermoresponsive responsive properties, allowing the triggering of coacervation after the phages have had some time in the aqueous REE containing solution. The resulting slurry makes it fairly easy to separate the phages from the collected REE ions, with the phages ready for another cycle afterwards. Creating more of these modified phages is also straightforward, with the papers showing the infecting of E. coli to multiply the phages.

Whether the recovery rate and ability to scale makes it an economically feasible method of REE recovery remains to be seen, but it’s definitely another fascinating use of existing biology for new purposes.

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Tick, Tock, Train Station Clock

We’ve seen a few H-bridge circuits around these parts before, and here’s another application. This time we have an Old Train Station Clock which has been refurbished after being picked up for cheap at the flea market. These are big analog clocks which used to be common at railway stations around the world.

This build uses an ESP32 C3-mini microcontroller (PDF) in combination with an A4988 Microstepping Motor Driver (PDF). The logic is handled with MicroPython code. The A4988 provides two H-bridge circuits, one for each of two stepper motors, only one of which is used in this build.

The controller for this clock needs to send an alternating positive then negative DC pulse every minute to register that a minute has passed so the clock can update its hour hand and minute hand as appropriate. The ESP32 and the A4988 H-bridge cooperate to make that happen. The wifi on the ESP32 C3-mini is put to good use by facilitating the fetching of the current time from the internet. On an hourly basis the clock gets the current time with a HTTP call to a time server API, for whatever is suitable for your time zone.

Thanks to [PiotrTopa] for writing in to let us know about his project. If you’re interested in learning more about H-bridge applications be sure to check out Introduction To The H-bridge Motor Controller and A H-Bridge Motor Controller Tutorial Makes It Simple To Understand.

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Bringing A Yagi Antenna to 915MHz LoRa

If you’re a regular reader of Hackaday, you may have noticed a certain fondness for Meshtastic devices, and the LoRa protocol more generally. LoRa is a great, low-power radio communications standards, but sometimes the antennas you get with the modules can leave you wanting more. That’s why [Chris Prioli] at the Gloucester County Amateur Radio Club in the great state of New Jersey have got a Yagi antenna for North America’s 915 MHz LoRa band.

Right out the gate, their article links to one of ours, where [tastes_the_code] builds a Yagi antenna for the European 868 MHz LoRa. Like [tastes_the_code], the radio club found [Chris]’s antenna gives much better reception than what came with the LoRa module. Looking out their window, instead of two Metastatic nodes with a stock antenna, one club member is now connecting to two hundred.
A simulation of the radiation pattern. Looks like a Yagi, alright.
Now, the Yagi is directional, so you only get that boost pointed down the axis of the antenna, but at least in simulation they estimate a 7.7 dB front-to-back gain vs under 3 dB for an omnidirectional antenna. Not bad, for a simple 3D print and some stiff wire!

If you don’t want to re-invent the wheel again, check out the GCARC’s GitHub for files if you’re in North America. If you’re in Europe, check out [taste_the_code]’s build from last year. Of course whatever band you’re operating in, Yagi isn’t your only roll-your-own option for a LoRa antenna.

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Escaping the Linux Networking Stack at Cloudflare

Courtesy of the complex routing and network configurations that Cloudflare uses, their engineers like to push the Linux network stack to its limits and ideally beyond. In a blog article [Chris Branch] details how they ran into limitations while expanding their use of soft-unicast functionality that fits with their extensive use of anycast to push as much redundancy onto the external network as possible.

The particular issue that they ran into had to do with the Netfilter connection tracking (conntrack) module and the Linux socket subsystem when you use packet rewriting. For soft-unicast it is important that multiple processes are aware of the same connection, yet due to how Linux works this made it impossible to use packet rewriting. Instead they had to use a local proxy initially, but this creates overhead.

To work around this the solution appeared to be to abuse the TCP_REPAIR socket option in Linux, which normally exists to e.g. migrate VM network connections. This enables one to describe the entire socket connection state, thus ‘repairing’ it. Combined with TCP Fast Open to skip the whole handshake bit with a TFO ‘cookie’. This still left a few more issues to fix, with an early demux providing a potential solution.

Ironically, ultimately it was decided to not break the Linux networking stack that much and stick with the much less complicated local proxy to terminate TCP connections and redirect traffic to a local socket. Unfortunately escaping the Linux networking stack isn’t that straightforward.

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Rectal Oxygenation Could Save Your Life One Day

Humans have lots of basic requirements that need to be met in order to stay alive. Food is a necessary one, though it’s possible to go without for great stretches of time. Water is more important, with survival becoming difficult beyond a few days in its absence. Most of all, though, we crave oxygen. Without an air supply, death arrives in mere minutes.

The importance of oxygen is why airway management is such a key part of emergency medicine. It can be particularly challenging in cases where there is significant trauma to the head, neck, or surrounding areas. In these cases, new research suggests there may be an alternative route to oxygenating the body—through the rear.

When Nothing Else Works

Promising rials have been run with mammal subjects, while human testing is at an early stage. Credit: research paper
Most of us are familiar with the usual route of human respiration. We take in air through the mouth and nose, and it passes through the windpipe and into the lungs, where oxygen diffuses into the blood. When everything in the body is functional, this system works well. However, when things go wrong, it can suddenly become very difficult to keep a body alive.

Head or neck injuries can block the airway entirely, or infections can fill the lungs with fluid, preventing the transfer of oxygen to the blood. Supportive ventilation methods can help, but can often damage the lungs themselves while in use. When the lungs themselves cease to function at all, often the only real option is the use of a technique called extracorporeal membrane oxygenation, or ECMO. This is where complicated machinery is used to manually oxygenate the blood outside the body. It’s a complex method that can result in major complications, and comes with a wide range of potential side effects, some of which can be fatal.

In these life-or-death situations, it would be desirable to have an alternative oxygenation technique that could be used when the lungs or airway are badly compromised. New research has suggested that enteral ventilation could be just the ticket. It’s a rather out of the box method, involving the use of a special oxygen-carrying liquid called perfluorodecalin. By administering this fluid rectally, it may be possible to deliver oxygen to a patient without having to rely on the function of the lungs themselves.

As you might guess by the name, perfluorodecalin is a flurocarbon. Its molecules are made up of 10 carbon and 18 fluorine atoms, and it exists as a liquid at room temperature. It’s considered chemically and biologically inert, which is key to its use in a medical context. Beyond that, it’s capable of dissolving a great deal of oxygen, with 100 mL of perfluorodecalin able to dissolve 49 mL of oxygen at a temperature of 25 C. The fluid can also carry carbon dioxide, too. Historically, it’s been used as a method to supply oxygen to specific areas of the body in a topical application, and also used as a way to preserve organs or other tissues in an oxygen-rich environment.

Thus far, research remains at an early stage. Initial testing focused on supplying a rectal dose of non-oxygenated perfluorodecalin of 25 to 1,500 mL for up to 60 minutes, at which point patients would excrete the fluid on their own terms. Patients had their vital signs monitored and were studied for any possible adverse effects. The study found that only mild side effects occurred, specifically involving abdominal bloating and pain at higher levels which resolved without further intervention after the procedure was completed. No perfluorodecalin or related compounds were detected in the bloodstream in the immediate aftermath.
Enteral ventilation is still highly experimental, but early phase testing has shown promising results. Credit: research paper
The first stage of clinical testing was focused on establishing safety profiles rather than outright testing the efficacy of rectal oxygenation. Nonetheless, even in testing with non-oxygenated perfluorodecalin, the study showed a “modest increase” in oxygen saturation in patients dosed with higher amounts of the fluid (500 mL and 1000 mL). This is a positive sign that this could be a viable route for oxygenation, but more research will be needed to verify the findings and develop the technique into something that could have actual clinical applications. That can be a particularly slow process due to the extensive safety requirements of new medical treatments, but such regulations exist for good reason.

First Rodeos And All That

Regular mechanical ventilation can be a highly invasive procedure; liquid ventilation via the lungs would likely be far more so. In contrast, enteral ventilation doesn’t put the usual airway at any real risk of damage. Credit: Nolundi Rawana, CC BY-SA 3.0
It’s not the first time that physicians have explored alternate methods of delivering oxygen to the body. Other methods of liquid ventilation have been developed, albeit with a focus on delivering oxygen-rich liquids to the lungs themselves. The aim is generally to avoid the lung damage that is often caused by traditional positive-pressure ventilation systems, which can be particularly harmful to patients who are already badly unwell. Similarly, these methods typically use oxygen-rich flurocarbons to do the job. While there have been some promising studies, ultimately the technique remains experimental and challenging to implement.

Enteral ventilation has one major benefit over liquid ventilation using the lungs, precisely because it doesn’t involve the lungs at all. The body’s main airway can remain entirely unobstructed during such a treatment, and does not have to be filled with fluids or tubes that could cause damage on their own. In cases where the airway or lungs are badly damaged or compromised, these techniques could potentially help where liquid ventilation via the lungs would simply not be possible. There can be immediate risks in delivering any kind of liquid to a patient’s lungs, particularly if the transition to liquid breathing doesn’t go to plan. The same simply isn’t true of doing so via the enteral pathway, as the regular airway remains untouched and as functional as it ever was.

As it stands, you’re unlikely to be breathing via the rectum any time soon. However, some years down the line, your local emergency room or ICU might just have another route to administer oxygen when all the standard methods fail. It might be weird and unconventional, but it could help save lives.

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Measuring Caffeine Content At Home

By far, the most widely used psychoactive substance in the world is caffeine. It’s farmed around the world in virtually every place that it has cropped up, most commonly on coffee plants, tea plants, and cocoa plants. But is also found in other less common plants like the yaupon holly in the southeastern United States and yerba maté holly in South America. For how common it is and how long humans have been consuming it, it’s always been a bit difficult to quantify exactly how much is in any given beverage, but [Johnowhitaker] has a solution to that.

This build uses a practice called thin layer chromatography, which separates the components of a mixture by allowing them to travel at different rates across a thin adsorbent layer using a solvent. Different components will move to different places allowing them to be individually measured. In this case, the solvent is ethyl acetate and when the samples of various beverages are exposed to it on a thin strip, the caffeine will move to a predictable location and will show up as a dark smudge under UV light. The smudge’s dimensions can then be accurately measured to indicate the caffeine quantity, and compared against known reference samples.

Although this build does require a few specialized compounds and equipment, it’s by far a simpler and less expensive way of figuring out how much caffeine is in a product than other methods like high-performance liquid chromatography or gas chromatography, both of which can require extremely expensive setups. Plus [Johnowhitaker]’s results all match the pure samples as well as the amounts reported in various beverages so he’s pretty confident in his experimental results on beverages which haven’t provided that information directly.

If you need a sample for your own lab, we covered a method on how to make pure caffeine at home a while back.

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