Author Archives: pappp

More Adventures in Tiny Stepper Motors and Drivers

A tiny stepper motor being driven by a TMC2208 Stepstick

Last summer I posted about some tiny stepper motors from the internet, thinking about them as an alternative to mechatronic standbys like those terrible SG90 type servos or larger and differently terrible 28BYJ-48 geared steppers driven through a ULN2003.

At the time, I tried one with an A4988 stepstick from the top of my parts bin, and it didn’t work, so I figured there was some limitation and stuck to directly driving with H-bridges.
…it turns out the “limitation” was that the cheap current-setting potentiometer on that particular stepstick was broken so it was driving no output current.

Discoveries:

  • Those little bipolar stepper motors work fine with bipolar stepper drivers.
  • Generational gains in bipolar stepper driver ICs are substantial (eg. A4988 -> TMC2208).
  • The venerable 28BYJ-48 unipolar stepper motor is easily modified to run from bipolar drivers.
Continue reading
Posted in DIY, Electronics, General, Objects | Leave a comment

Intel iAPX 432

Source: Hacker News

Article note: Just paraphrasing my comment in the HN discussion on my own medium: The 432 was the first of Intel's many expensive lessons about the problems with extremely complicated ISAs dependent on even more sophisticated compilers making good static decisions for performance. Then they did it again with the i860. Then they did it again with Itanium. Some reasonably substantiated opinions: 1. Highly sophisticated large-scale static analysis keeps getting beaten by relatively stupid tricks built into overgrown instruction decoders, working on relatively narrow windows of instructions. 2. The primary reason for (1) is that performance is now almost completely dominated by memory behavior, and making good static predictions about the dynamic behavior fancy memory systems in the face of multitasking, DRAM refresh cycles, multiple independent devices competing for the memory bus, layers of caches, timing variations, etc. is essentially impossible. 3. You can give up on a bunch of your dynamic tricks and build much simpler more predictable systems that can be statically optimized effectively. You could probably find an good local maxima in that style. The dynamic tricks are, however, unreasonably effective for performance, and have the advantage that they let you have good performance with the same binaries on multiple different implementations of an ISA. That's not insurmountable (eg. the AOT compilation for ART objects on Android), but the ecosystem isn't fully set up to support that kind of thing.
Comments
Posted in News | Leave a comment

The many derivatives of CP/M

Source: Hacker News

Article note: Huh, that family tree is more complicated than I knew, and I've played with several things along it.
Comments
Posted in News | Leave a comment

Installing SKS B53 Fenders on a Giant Escape Disc

Giant Escape 3 Disc with SKS B53 Fenders
Giant Escape 3 Disc with SKS B53 fenders, modified to fit

I’ve been biking a fair amount lately after a 20-odd year hiatus; I decided last year that I wanted to start biking, bought a Giant Escape 3 Disc near the end of summer, but didn’t get confident enough riding to use it around campus last year among the students texting their way to their first (next?) vehicular manslaughter charge before they flocked back.

This summer, I’ve been dong my commute into campus on it, plus a significant amount of fun/exercise riding, and the top fixable annoyance has become getting sprayed at the slightest hint of wet. I did some hackin’ that I haven’t seen on the interwebs to fit the fenders I picked to the frame, which is the point of this post.

Continue reading
Posted in DIY, General, Objects | Leave a comment

SGX, Intel’s supposedly impregnable data fortress, has been breached yet again

Source: Ars Technica

Article note: The search method is neat, they found that the collection of known processor vulnerabilities in pairs (every transient execution vulnerability had a static ISA vulnerability with the same underlying mechanism)... except for one where there were only known transient attacks. So they built tools to hunt for it, and sure enough, ISA vulnerability. Which renders SGX useless (again). Demonstrating, once again, that high-complexity ISA features will cause bugs, either by implementation bugs or interactions.
SGX, Intel’s supposedly impregnable data fortress, has been breached yet again

Enlarge (credit: Intel)

Intel’s latest generation of CPUs contains a vulnerability that allows attackers to obtain encryption keys and other confidential information protected by the company’s software guard extensions, the advanced feature that acts as a digital vault for security users’ most sensitive secrets.

Abbreviated as SGX, the protection is designed to provide a fortress of sorts for the safekeeping of encryption keys and other sensitive data, even when the operating system or a virtual machine running on top is maliciously compromised. SGX works by creating trusted execution environments that protect sensitive code and the data it works with from monitoring or tampering by anything else on the system.

Cracks in Intel’s foundational security

SGX is a cornerstone of the security assurances many companies provide to users. Servers used to handle contact discovery for the Signal Messenger, for instance, rely on SGX to ensure the process is anonymous. Signal says running its advanced hashing scheme provides a “general recipe for doing private contact discovery in SGX without leaking any information to parties that have control over the machine, even if they were to attach physical hardware to the memory bus.”

Read 17 remaining paragraphs | Comments

Posted in News | Leave a comment

Ask HN: Why did smartphones become a single point of failure?

Source: Hacker News

Article note: I rage about this a lot. My phone is my least-trustworthy, most loss/theft-prone computer. The Phone network is a security shamble. All the blackbox vendor apps doing "security" are a threat to each other. Why are you assholes trying to use it as a trust root instead of letting me dump something in my password manager DB?
Comments
Posted in News | Leave a comment

Netflix Piracy Thrives as Subscribers Rethink Their Streaming Subscriptions

Source: TorrentFreak

Article note: And the rule maintains. If piracy is a better overall experience than the official option, on an experience/cost/effort basis, then piracy wins. Fragmenting content libraries into a bunch of individual expensive services -> Piracy. Adding friction to using services across devices/locations -> piracy. Costs exceeding perceived value -> piracy.

pirate streamAs the first major legal subscription streaming service on the Internet, Netflix paved the way for a streaming revolution.

The company began competing with piracy from the get-go, branding itself as a superior alternative. In the early years, the strategy paid off.

Millions of subscribers switched from casually consuming pirated content on unlicensed platforms in favor of a convenient and reasonably-priced legal alternative. Piracy never went away, but downloading Netflix content illegally seemed silly.

Streaming Wars

In the years that followed the legal streaming landscape became more crowded. Inspired by Netflix’s success, new streaming portals such as Amazon, Disney+, HBO Max, Hulu, Paramount+, and Peacock started competing for a share of the lucrative streaming market.

The media often refers to this competition as the “streaming wars,” but the real threat may not come from legal streaming services but illegal pirate sites.

The suggestion that “subscription fatigue” may motivate people to start pirating again isn’t new. We have highlighted this issue in the past and it has been confirmed by research, but it’s now reaching a point where it’s hard for Hollywood to ignore.

Piracy tracking firm MUSO recognizes the problem too. In addition to doing anti-piracy work for major copyright holders, the UK company also helps major players such as Amazon, Lionsgate, and Sony, to understand the latest piracy trends.

Piracy is Appealing Once Again

In an op-ed, MUSO CEO Andy Chatterley highlights that increased fragmentation in the streaming ecosystem, paired with higher prices, is starting to make piracy more appealing again. And without an option to pay for everything, people are seeking out alternatives.

“[F]aced with an increasingly fractured streaming landscape, the consumer does the math and realizes that having access to all the shows they want to watch is not a justifiable expense when their grocery bill has doubled and they’re cycling or carpooling to work to save money on fuel,” Chatterley says.

“And in the absence of a one-stop shop like Spotify is to music lovers, and now that piracy sites have evolved to become sophisticated, easy-to-use experiences, people who have never resorted to piracy before are finding it more appealing than ever. Everything you could ever want to watch, all in one place, only a few clicks away and all for free. What’s not to like?”

Netflix Piracy Thrives

Chatterley notes that copyright holders should be aware of this potential shift in user behavior, which is backed up by data. Earlier this year Netflix reported that its subscriber numbers had dropped for the first time in history and piracy continues to grow.

According to MUSO’s data, Netflix content was good for an 11.4% U.S. piracy market share in June. Globally, this number is even higher, with Netflix content making up 16% of the worldwide piracy demand.

“Now, imagine if they could convert those pirate consumers into paying customers,” Chatterley comments.

MUSO’s messaging is in part out of self-interest as the company offers piracy insights as a commercial service. This is serious business for Muso. Just last week the company announced that it had secured a $3.9M investment from Puma Private Equity.

A One-Stop Streaming Solution?

That said, the fact that a company working with several Hollywood players is prepared to highlight the dangers of too many subscriptions is quite something. Especially when that company started as a fairly traditional anti-piracy outfit roughly a decade ago.

Instead of pointing a finger at pirates, Chatterley focuses more on the shortcomings of the TV and movie industry. Piracy can be lowered by offering a one-stop solution for a fair price but somehow that seems to be a pipe dream.

“By offering a service that is both comprehensive and good value for money, you render piracy a much less attractive option,” he writes.

“But with content providers investing billions in their platforms and determined to keep their shows exclusive to them, this seems fanciful. And so the drop off in subscribers seems set to continue, with piracy sites continuing to welcome them with open arms,” Chatterley concludes.

From: TF, for the latest news on copyright battles, piracy and more.

Posted in News | Leave a comment

Trump says the FBI has raided Mar-a-Lago

Source: The Week: Most Recent Home Page Posts

Article note: Oh yes. Yes please.

Former President Donald Trump said in a statement on Monday evening that the FBI executed a search warrant at his Mar-a-Lago resort in Palm Beach, Florida.

Trump said Mar-a-Lago "is currently under siege, raided, and occupied by a large group of FBI agents. Nothing like this has ever happened to a president of the United States before. After working and cooperating with the relevant government agencies, this unannounced raid on my home was not necessary or appropriate."

Trump went on to claim that this "is prosecutorial misconduct" and "the weaponization of the justice system," adding that "such an assault could only take place in broken, Third World countries. Sadly, America has now become one of those countries, corrupt at a level not seen before. They even broke into my safe!" NBC News reports that Trump is in New York City, and has spent the summer at his club in Bedminster, New Jersey.

Dave Aronberg, the Palm Beach County state attorney, told MSNBC's Jason Johnson that his office was not involved in the search, which was "kept close to the vest" by the FBI. Aronberg said he thinks Trump "will believe that this is crossing a red line. This is his inner sanctum. To get this raid of his place, there had to be a warrant signed off by a judge. There needs to be probable cause. There needs to be a belief that there's evidence there that could lead to a crime. It can't be a fishing expedition. So this is definitely serious stuff."

It's not known at this time "what crime are they pursuing and who are they pursuing," Aronberg continued, but "I do not believe they are searching Mar-a-Lago to build a case against someone else who lived there or a guest of the place. That is Donald Trump's home and I think it shows further evidence that the Department of Justice is indeed looking at Donald Trump himself."

Posted in News | Leave a comment

Citing danger of “ink spills” Epson programs end of life for some printers

Source: OSNews

Article note: Wow. I thought my HP breaking 3rd party toner support in an update after sale was bad, but this is a new level of shitty.

You have a perfectly healthy, functioning Epson inkjet printer in your home office. It’s served you well for years and you use it frequently. Then, one day, you go to print a document and realize that the printer isn’t working. A message on the display reads “a part inside your printer is at the end of its service life. Service is required.”

That’s funny, you think. You hadn’t noticed anything wrong with your printer before this message appeared. The device was working well and the quality of the printing was fine. If nothing was broken, why are you suddenly getting this message? More important: how do you get rid of it so that you can continue using your printer?

This should absolutely be criminal behaviour. If there was ever an industry that could do with a worldwide judicial probe and investigation, it’s the printer makers. They employ so many clearly scammy business practices, and get away with them too.

Posted in News | Leave a comment

Debugging bare-metal STM32 from the seventh level of hell

Source: Hacker News

Article note: I like the "debug journal" genre, this is a good one with a good lesson. That lesson being that the bring-up for the gigantic pile of mismatched IPs glued together in a modern uC is incredibly fiddly, and if a micro-controller data sheet says "wait for X" you can get away doing everything _then_ waiting for it to settle until you can't, at which point it punches you in the taint.
Comments
Posted in News | Leave a comment