HN rank: 1

HN score: 356

comments: 186

original url: https://rvembedded.com/blog_post/12/

评论信号：I think he's kind of speaking past the original author. The original piece is basically about how the author doesn't think that RISC-V will take off outside embedded, because of some design decisions that lead to poor performance compared to ARM64 and because so much of the ISA being optional means that there's too much fragmentation to make binary distribution feasible. Meanwhile, this piece is mainly about how RISC-V is great for embedded because companies can build it into custom chips with specifically the functionality they need, and because of how cheap it is for low-end use cases since there's no license fees.The only real point of contention I see between the two is that this piece goes on to talk about how it's a selling point that RISC-V can be used for both low-end 10 cent microcontrollers, and high-end multi-core processors running Linux. Personally I don't see the benefit of this since you're going to have to recompile your software anyway, and since all the RISC-V SBCs I'm aware of have significantly worse performance and efficiency than comparably priced ARM SBCs. reply:...

评论信号：I believe there will come a day when RISC-V has comparable or better performance than ARM and x86_64.This is based on history: I remember when x86 performance compared to the DEC Alpha, PA-RISC, SPARC, etc. was a joke. There was a time when, if you wanted real performance, you needed to pony up $20,000-$50,000 for a workstation with a MIPS/PA-RISC/SPARC/Alpha/whatever processor. All these workstations smoked the x86 computers of the era.However, people were buying x86 computers at a far higher rate, giving Intel (and AMD) the money needed to invest in better chip designs and better fabs. Linux was, at the same time, gaining traction and, around the time the dot-com bubble popped and there were no longer companies with the money needed to get Sun SPARC workstations (or what not) at $50,000 or more a pop to start up a web business, x86 computers running Linux had nearly the same performance at a much lower price. Once the Itanium sank and x86_64 was mainstream, x86_64 was the ISA of choice for performance workstations and servers, and the RISC ISAs that survived were now mainly used in the embedded space....

评论信号：I don't really understand the author's conclusions about cost and shipping, and how RISC-V is cheaper and more accessible to people outside the US and Europe. He first talks about how getting $1 worth of chips can cost $60-$200 in shipping for him due to his location... but then by the end claims that RISC-V gives him "an architecture that arrives in my country at ten cents a part".I don't get how both things can be true. The cost to ship something to Trinidad and Tobago has nothing to do with whether it's ARM or RISC-V; shipping the same weight of either kind of chips should cost exactly the same amount. Yes, maybe the chip cost itself of a particular ARM-based model is $0.15 while the equivalent RISC-V chip costs $0.10, but if the issue (for him and other people who live outside US/Europe) is that shipping costs are orders of magnitude more expensive than the thing being shipped, that chip-cost difference becomes irrelevant.I think he does make a great point about how fragmentation does give you better optionality:... reply: He's saying that shipping from the big western parts suppliers (Digikey, Mouser, Segger) costs a lot of money....

HN rank: 2

HN score: 525

comments: 221

original url: https://platform.claude.com/docs/en/release-notes/system-prompts

评论信号：I have a folder where I rebuild these as a git commit history so you can more easily see what has changed: https://github.com/simonw/research/commits/main/extract-syst...For example here's what changed between Opus 4.8 and Opus 5: https://github.com/simonw/research/commit/a2de185cc367eb66c2...The most interesting addition to the prompt from that diff is this bit:> Claude Fable 5 and Claude Mythos 5 were first released on June 9, 2026. On June 12, 2026, Anthropic suspended access to both models to comply with U.S. Department of Commerce export controls; the Department lifted those controls on June 30, 2026, and Anthropic restored access on July 1, 2026 (Anthropic's statement: https://www.anthropic.com/news/fable-mythos-access). These events are after Claude's training-data cutoff, so Claude knows about them only from this notice. If asked, Claude confirms them accurately and matter-of-factly — it doesn't deny the suspension happened — and otherwise treats the export controls like any other current political topic:... reply:...

评论信号：Offtopic. I have a concern that this forum is removing stories that have negative connotation on AI.Few days back, I posted an article[1] that was about how AI threatens natural resources for billions. This was from United Nations and it was flagged. I did not think much about it until I saw two other stories [2] & [3] today that were doing fairly good on front page but they suddenly disappeared. They are not even on 2nd or 3rd page. I have seen this happening at other times as well but did not document it. Just thought you all should know about this.I was going to create Tell HN thread but I thought the same would happen with it too. I am pretty sure this thread is not going anywhere so I'm posting my concern here.[1]: https://news.ycombinator.com/item?id=49290062[2]: https://news.ycombinator.com/item?id=49318906[3]: https://news.ycombinator.com/item?id=49319582 reply: > how AI threatens natural resources for billions.The article rests on the claim that water usage of data centers on continent X threaten water availability for humans on continent Y.I hope you can see how self-evidently illogical that is....

评论信号：Those are remarkably longer than I would expect, or think is warranted. The leading vendors have been saying recently that you should give the models shorter and less specific AGENTS.md (or whatever) files, and in my experience, that's good advice. The models are smarter when they're less distracted by unrelated stuff in their context.So, why so much noise in the system prompt? Most of the time most of it will not apply. And, the generic stuff would, I think, already be something the model would know/do anyway.I've noticed agent skills written by models make the same mistakes; e.g. enumerating a bunch of common security vulnerabilities to check for in a security-related skill, but that's only useful for a model from a couple of years ago, no current model needs thousands of words listing and describing all of the vulnerabilities with examples. Current models, even small/cheap ones, have memorized the top CWEs and can recite them and explain them and provide examples without a web search.It feels like a CYA document. Which, I guess a company of their size and influence has to do. But, it still feels like waste time say lot word when few word do trick.

HN rank: 3

HN score: 66

comments: 28

original url: https://pikuma.com/blog/programming-intel-pentium-mmx-simd

评论信号：When MMX first came out and there were games that supported it, many reviewers were convinced that it improved 3D performance. As far as I could tell, it wasn't really used for 3D and that the only enhancement was to the audio system. But the placebo effect of "If has MMX thus its better" did stick around for a long while.An aside, but when SSE came a long that was a real big leap in 3D performance, just as GPU's started to gain some independence. So in about 2010, I tried to fire up Turok 2 just to see how fast it would run on a then modern CPU/GPU setup. It couldn't crack 200fps, however games only a year or two later would fly way past that. Turok 2 came out just before SSE and thus basically ran in purely x86/x87 space, thus the performance gap.

评论信号：Author here. Thanks for sharing.

评论信号：> Each MMX register is 64 bits wide. Internally, the MMX registers were aliases of the x87 floating-point registers.Due to the way the first Pentium 3 CPUs (Katmai) were built, they likewise aliased the x87 (and thus, MMX) registers to the XMM SSE registers, but this was hidden from programs. It wasn't until at least the Coppermine revision that they were separate registers again. reply: I remember hearing a rumour as a young teen that the Coppermine codename meant it actually had copper wiring and that's what made it faster somehow. Copper has lower resistance than aluminium and can therefore help chips run faster - it makes sense! But it was just a codename and the coppermine had aluminium interconnects.My family got a PIII 533Mhz coppermine, in the early sideways Slot 1 configuration. Blazing fast at the time. Been a long time since I heard anyone say "coppermine".CPU progress was wild in the 90s, where you could wait two years and your new CPU would be double the old one's speed at the same price point. Today it takes near a decade for CPU speed to double.I also recall the first game that advertised its exciting use of the new MMX technology:...

HN rank: 4

HN score: 87

comments: 22

original url: https://wiki.lowtechlab.org/wiki/Filtre_%C3%A0_eau_c%C3%A9ramique/en

评论信号：Ceramic filters are very common in Brazil, used in clay recipients which also keep the water cool even in summer without spending energy.https://g1.globo.com/saude/noticia/2026/03/14/filtro-de-barr... reply: Mostly in rural regions, but the 'filtro de barro' water from your grandma's house beats ANY expensive filter you can get, haha!

评论信号：There is a company[1] in Indonesia that actually makes very nice versions of this tech.[1] https://www.terrawaterindonesia.com/ reply: That ad claims it removes microplastics. I was led to believe there are few easy ways to accomplish such a thing. Is this a, "Well technically, we started at 100ug/mL and ended at 99.8ug/mL => reduction!" or is this a meaningful improvement in water quality? The pot looks to just be clay + charcoal + silver - which is not significantly different from other home water filtration systems.

评论信号：When I was a kid, we'd go camping, and we had these water filters that you would pump water through, and they would filter it.It was ceramic, and I think it was the same idea, but we used a pump to force the water through (like a bicycle pump).

HN rank: 5

HN score: 36

comments: 13

original url: https://bernsteinbear.com/blog/zkp/

评论信号：Amazing article. Will save to explain ZKP to others.One tiny correctionrandom.randrange(100) gives 300 possible commitments(3 colors for hundred nonces) After seeing a couple of revealed edges, the verifier can figure out the palette and brute-force all 300 combinations, effectively opening every commitment.It can be mitigated if we use 128 bits of randomness, e.g. secrets.token_bytes(16).Also I would use sha256 instead of hash. Python hash is not considered secure as it does not have proper collision resistance.

评论信号：Not one mention that ZKP depends on servers trusting clients.The single reason ZKP is not viable for most security is that it relies on you trusting the client to send you true information about data.With conventional security the user sends their inputs and the server validates it.Something I notice that is almost never mentioned when people bring up ZKP - it is pretty much only for peer-to-peer when there is no authoritative server. Or when that server trusts the “nodes” (clients). reply: ZKP's are not magic, you need a cryptographic operation on which to operate the ZKP. this way you can conceal the input while still proving something about it. this works because the ZKP follows the trace of execution through the cryptographic primitive which proves it was executed properly and then the output was validated by some public measure.conversely, if ZKP's ever get fast enough to be useful for this you can prove a public input (ex. source code) was compiled properly into a public output (ex. binary). for obvious reasons doing this only makes sense when it's efficient otherwise you can just execute it yourself.

评论信号：ZKP is 100% bullshit.It’s a new word invented by people who don’t know hashing and databases already exist. reply: PAKE has been using ZKPs for a decade. Here. Read this : https://en.wikipedia.org/wiki/Password_Authenticated_Key_Exc...Funny that not only are you ignorant you are violently confident in your ignorance. I suffer from this sometimes too so I get it. Get some help.