Illustrative models of collinear ferromagnetism, antiferromagnetism, and altermagnetism in crystal-structure real space and nonrelativistic electronic-structure momentum space. (Credit: Libor Šmejkal et al., Phys. Rev. X, 2022)

Nanoscale Imaging And Control Of Altermagnetism In MnTe

December 21, 2024 by Maya Posch No comments

Altermagnetism is effectively a hybrid form of ferromagnetism and antiferromagnetism that might become very useful in magnetic storage as well as spintronics in general. In order to practically use it, we first need to be able to control the creation of these altermagnets, which is what researchers have now taken the first steps towards. The research paper by [O. J. Amin] et al. was published earlier this month in Nature. It builds upon the team’s earlier research, including the detection of altermagnetism in manganese telluride (MnTe). This new study uses the same material but uses a photoemission electron microscope (PEEM) with X-rays to image these nanoscale altermagnetic structures.

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Intel Terminates X86S Initiative After Formation Of New Industry Group

December 21, 2024 by Maya Posch 59 Comments

Although the world of the X86 instruction set architecture (ISA) and related ecosystem is often accused of being ‘stale’ and ‘bloated’, we have seen a flurry of recent activity that looks to shake up and set the future course for what is still the main player for desktop, laptop and server systems. Via Tom’s Hardware comes the news that the controversial X86S initiative is now dead and buried. We reported on this proposal when it was first announced and a whitepaper released. This X86S proposal involved stripping 16- and 32-bit features along with rings 1 and 2, along with a host of other ‘legacy’ features.

This comes after the creation of a new x86 advisory group that brings together Intel, AMD, as well as a gaggle of industry giants ranging from HP and Lenovo to Microsoft and Meta. The goal here appears to be to cooperate on any changes and new features in the ISA, which is where the unilateral X86S proposal would clearly have been a poor fit. This means that while X86S is dead, some of the proposed changes may still make it into future x86 processors, much like how AMD’s 64-bit extensions to the ISA, except this time it’d be done in cooperation.

In an industry where competition from ARM especially is getting much stronger these days, it seems logical that x86-oriented companies would seek to cooperate rather than compete. It should also mean that for end users things will get less chaotic as a new Intel or AMD CPU will not suddenly sneak in incompatible extensions. Those of us who remember the fun of the 1990s when x86 CPUs were constantly trying to snipe each other with exclusive features (and unfortunate bugs) will probably appreciate this.

Fixing 1986 Sinclair Spectrum+2 With A High-Score Of Issues

December 19, 2024 by Maya Posch 6 Comments

The Sinclair ZX Spectrum+2 was the first home computer released by Amstrad after buying up Sinclair. It’s basically a Sinclair ZX Spectrum 128, but with a proper keyboard and a built-in tape drive. The one that [Mark] of the Mend it Mark YouTube channel got in for repair is however very much dead. Upon first inspection of the PCB, it was obvious that someone had been in there before, replacing the 7805 voltage regulator and some work on other parts as well, which was promising. After what seemed like an easy fix with a broken joint on the 9 VDC input jack, the video output was however garbled, leading to the real fault analysis.

Fortunately these systems have full schematics available, allowing for easy probing on the address and data lines. Based on this the Z80 CPU was swapped out to eliminate a range of possibilities, but this changed nothing with the symptoms, and a diagnostic ROM cartridge didn’t even boot. Replacing a DS74LS157 multiplexer and trying different RAM chips also made no difference. This still left an array of options on what could be wrong.

Tracking down one short with an IC seemed to be a break, but the video output remained garbled, leaving the exciting possibility of multiple faults remaining. This pattern continues for most of the rest of the video, as through a slow process of elimination the bugs are all hunted down and eliminated, leaving a revived Spectrum+2 (and working tape drive) in its wake, as well as the realization that even with all through-hole parts and full schematics, troubleshooting can still be a royal pain.

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Human Civilization And The Black Plastic Kitchen Utensils Panic

December 19, 2024 by Maya Posch 98 Comments

Recently there was a bit of a panic in the media regarding a very common item in kitchens all around the world: black plastic utensils used for flipping, scooping and otherwise handling our food while preparing culinary delights. The claim was that the recycled plastic which is used for many of these utensils leak a bad kind of flame-retardant chemical, decabromodiphenyl ether, or BDE-209, at a rate that would bring it dangerously close to the maximum allowed intake limit for humans. Only this claim was incorrect because the researchers who did the original study got their calculation of the intake limit wrong by a factor of ten.

This recent example is emblematic of how simple mistakes can combine with a reluctance to validate conclusions can lead successive consumers down a game of telephone where the original text may already have been wrong, where each node does not validate the provided text, and suddenly everyone knows that using certain kitchen utensils, microwaving dishes or adding that one thing to your food is pretty much guaranteed to kill you.

How does one go about defending oneself from becoming an unwitting factor in creating and propagating misinformation?

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Survival mechanisms in Deinococcus radiodurans bacterium. (Credit: Feng Liu et al., 2023)

Bacterium Demonstrates Extreme Radiation Resistance Courtesy Of An Antioxidant

December 18, 2024 by Maya Posch 12 Comments

Extremophile lifeforms on Earth are capable of rather astounding feats, with the secret behind the extreme radiation resistance of one of them now finally teased out by researchers. As one of the most impressive extremophiles, Deinococcus radiodurans is able to endure ionizing radiation levels thousands of times higher than what would decisively kill a multicellular organism like us humans. The trick is the antioxidant which this bacterium synthesizes from multiple metabolites that combine with manganese. An artificial version of this antioxidant has now been created that replicates the protective effect.

The ternary complex dubbed MDP consists of manganese ions, phosphate and a small peptide, which so far has seen application in creating vaccines for chlamydia. As noted in a 2023 study in Radiation Medicine and Protection by [Feng Liu] et al. however, the D. radiodurans bacterium has more survival mechanisms than just this antioxidant. Although much of the ionizing radiation is neutralized this way, it can not be fully prevented. This is where the highly effective DNA repair mechanism comes into play, along with a range of other adaptations.

The upshot of this is the synthesis of a very effective and useful antioxidant, but as alluded to in the press releases, just injecting humans with MDP will not instantly give them the same super powers as our D. radiodurans buddy.

Featured image: Survival mechanisms in Deinococcus radiodurans bacterium. (Credit: Feng Liu et al., 2023)

The added 3.3v rail on the Raspberry Pi 500 PCB. (Credit: Samuel Hedrick)

Enabling NVMe On The Raspberry Pi 500 With A Handful Of Parts

December 18, 2024 by Maya Posch 73 Comments

With the recent teardown of the Raspberry Pi 500, there were immediately questions raised about the unpopulated M.2 pad and related traces hiding inside. As it turns out, with the right parts and a steady hand it only takes a bit of work before an NVMe drive can be used with the RP500, as [Jeff Geerling] obtained proof of. This contrasts with [Jeff]’s own attempt involving the soldering on of an M.2 slot, which saw the NVMe drive not getting any power.

The four tiny coupling capacitors on the RP500’s PCIe traces. (Source: Jeff Geerling)

The missing ingredients turned out to be four PCIe coupling capacitors on the top of the board, as well as a source of 3.3 V. In a pinch you can make it work with a bench power supply connected to the pads on the bottom, but using the bottom pads for the intended circuitry would be much neater.

This is what [Samuel Hedrick] pulled off with the same AP3441SHE-7B as is used on the Compute Module 5 IO board. The required BOM for this section which he provides is nothing excessive either, effectively just this one IC and required external parts to make it produce 3.3V.

With the added cost to the BOM being quite minimal, this raises many questions about why this feature (and the PoE+ feature) were left unpopulated on the PCB.

Featured image: The added 3.3 V rail on the Raspberry Pi 500 PCB. (Credit: Samuel Hedrick)

Documented Source Code For Elite On The C64, BBC Micro And Others

December 15, 2024 by Maya Posch 12 Comments

If you ever wanted to dive into the source code for the 1980s space game Elite, but didn’t want to invest many hours reverse-engineering the 6502 assembly code, then [Mark Moxon]’s annotated code has you covered. The systems referenced range from the BBC Micro and Commodore 64 to the NES and Apple II, with some of these versions based on the officially released source code. For other systems the available source code was used together with decompiled game binaries to determine the changes and to produce functional, fully commented source code.

The cutting-edge gameplay of Elite on the 8502.

This particular game is fascinating for being one of the first to use wire-frame 3D graphics with hidden-line removal and a sprawling universe in which to trade and deal with less than friendly parties using a variety of weapons. After this initial entry it would go on to spawn many sequels and inspired countless games that’d follow a similar formula.

On the respective GitHub project page for each version, you can find instructions on how to build the code for yourself, such as for the Commodore 64. Of note here is the license, which precludes anyone from doing more than forking and reading the code. If this is no concern, then building the game is as simple as using the assembler (BeebAsm) and the c1541 disk image utility from the VICE project.