invalidator

I'd say a type which doesn't have both a significand and an exponent isn't a float at all. How can you have a floating point with no ability to move the point?

To have something IEEE754-like you'd need a sign, significand, and exponent. That gets you +/-(0, 1, Inf, Nan). Add another bit to the exponent if you want non-integer values. That's the minimum for what I'd call a float.

If you really want to strip it down to one bit, you should choose which of those bits to keep. Significand gives you (0,1), which is the same as a uint1_t. Exponent arguably gives you (0, Inf). Sign gives you (-1,1).

Of those, I'd say the sign-bit, giving -1 and 1, is maybe the most practical, but it's not a complete float.

That's an interesting quirk! I thought they were all just USB-C ports internally. Do you know why this matters?

Torque is directly proportional to radius, all other factors being equal. There are practical limits on the strength of the magnetic force because you can only cram so many amps through a confined space, which is even more confined on a small motor.

It will still make high power at high RPMs, but you have to gear it down to convert that power into more torque at low speeds. A gearbox makes it not really a Hub Motor at all any more. Terminology aside, a gearbox also adds even more weight and complexity inside the wheel. For less weight and complexity you can use a half-shaft to the center of the vehicle and use whatever motor you want inboard.

I like little puzzles so I gave it a shot in Ruby.

  #!/usr/bin/ruby
  
  require 'digest'
  
  charmap = %w{zero one two three four five six seven eight nine a b c d e f}
  
  (0..0xf).map do |prefix|
    Process.fork do
      (0..0xffffff).each do |i|
        hex = "%01x%06x" % [prefix, i]  # "0123456"
        digit_words = hex.chars.map { |c| charmap[c.to_i(16)] }  # ["zero", "one", ...]
        sentence = "The SHA256 for this sentence begins with: %s, %s, %s, %s, %s, %s and %s." % digit_words
        sha = Digest::SHA256.hexdigest(sentence)
        if sha[0,7] == hex
          puts(sentence)
        end
      end
    end
  end
  
  Process.waitall

8 minutes on an old quad-core. I don't expect there's much to optimize since all the heavy lifting is in the libraries. I didn't bother with synchronization so you might get a scrambled result if it somehow finds a flurry of hits. :)

I've used this technique on several of my projects. The formed threads are strong and reliable. It cuts down assembly steps and BOM. The tight fit means the screws won't back out (like locktite or nylocks). The only downside is they can only be reassembled a few times before they start getting loose, at which point you can either add material (superglue), or just reprint the part.

If you have something you want to reassemble frequently, use inserts. If you're putting it together once and intend to use it that way for a long time, threadforming works fine.

> 1in = ???

25.4 mm, ever since 1959 when we redefined it.

Mostly yes. Your applications run in a standard Linux environment and if you pop up a terminal, hey, it's your favorite distro and it works.

There's some learning curve for features which exist for valid reasons, especially around communicating between domains. For instance, copy-and-paste between qubes requires extra steps. Plugging in a USB keyboard or mouse doesn't just work - you have to authorize it first (just click the OK button using a PS/2 mouse, or laptop's touchpad). You have to learn how to move files between qubes. USB drives, cameras, and microphones aren't globally available to all applications - you have to attach them to a qube first. You can install software using apt-get inside a qube, but it won't persist across reboots - you have to update the OS template.

I want those extra steps and complications - they are features, not a bugs! The first few days you'll be looking things up in the FAQ. After that it's pretty easy.

There are a few sore points that don't go away. You don't get GPU acceleration in your web browser, so rendering is slower. Gaming is not an option. Your application qubes live behind a firewall qube, so things that require network broadcast like Chromecast won't work. Those are fine for me but not for everyone.

They are providing the source as required. However, a key part of the GPL is that RH's customers should also be able to redistribute the source to anyone else, and RH is preventing that through contract law.

How comfortable are you with DIY electrics? Can you lay out a panel somewhere in the sun? Do you want it to run at night? Do you want it to automatically switch to grid power if needed?

They did roughly that with the previous hull: it was used until it had to be derated. This accident was on the replacement hull which already had a few cycles on it... tested but supposedly not worn out.

Material science is hard, especially on a budget. This is definitely daredevil territory.

The carbon fiber hull has a limited cycle life. It's designed for a single-digits number of dives, and it becomes weaker on each cycle.

NiMH handles gentle overcharging gracefully. They generate a little bit of hydrogen, and the battery has an internal catalyst to convert it back. It can do that indefinitely as long as it's at a low rate.

When aggressively overcharged they may rupture, but they don't go up in flames like Li-ion does.

> does wire-wrapping even exist any more?

Yes! I gave it a try a few years ago and I am impressed.

It's faster, denser, and cleaner than soldering wires onto perfboard. Being able to rework by just unwinding a wire is great. I don't use proper wirewrap sockets, but it seems reliable for one-off hobby prototypes.

Shutup10 is a good start.

It will always have some impact because you're thrashing the caches.

A couple more things to try:

Reduce swappiness. Linux tries to swap out idle pages to free memory for block cache, even when there's only light memory pressure. If you have a dozen processes working hard and your UI is untouched for several minutes, it can get swapped out and lag.

  sudo sysctl vm.swappiness=1

Set the CPU affinity for your build processes to exclude CPU 0, ensuring one is always free for UI:

  taskset 0xFFFFFFFE nice your_build_command_here

Neither is perfect but they can help.

A few years ago we couldn't upgrade the kernel because XFS had a regression. Our choices were: revert the XFS changes in the newer kernel; backport security fixes to the version we were already using.

We went with the latter because our minimal attack surface made it unlikely that we'd need to backport many fixes, but it was always looming.

Now realize that this applies to everything, not just computers. Unless you've walked a mile in their shoes, you don't really understand the struggles of LGBTQ folks, the homeless, CEOs, assembly line workers... They will try to tell you, but you can't tell people anything, unless you're telling someone with good imagination and empathy.

I worked at Sun around that time. Our version: "The network is the computer, and Cisco is the network... therefore Cisco is the computer."

If you're looking for chips / SOCs which implement a given arch, this Wikipedia template from the article is pretty good: https://en.wikipedia.org/wiki/Template:Application_ARM-based...

If you want to find a consumer device which implements a specific arch, you can take the list of SOCs from above, and select them in "Chipset" in GSMArena's search: https://www.gsmarena.com/search.php3?

> The kernel is armv6l and I still don’t know what the last letter is for.

ARM is bi-endian. I'm pretty sure the 'l' means the kernel was compiled to be little-endian.

> apt is just annoyingly slow

A lot of that is due to aggressive use of fsync. apt tries hard to be robust against power failures when changing the system.

When using it for something ephemeral (say, part of a CI workflow) you can disable fsync and let it rip. It's still not as fast as apk but it's several times faster than normal.

  apt-get -yq install eatmydata
  eatmydata apt-get -yq install (all the other things)

The DS1104Z has a MSO option: if you add the RPL1116 logic probes, you can sample 8 channels at 1GSa/s, or 16 ch at 500MSa/s. That should be easily capable of capturing 80MHz SPI.

The downside to using a scope is it's much clunkier than using a LA on a PC. The decoder option it will give you the data, but if you're doing more than a handful of bytes, it gets tedious to scroll through hex dumps on screen and manually copying out the parts you want.

Saleae's software is delightful for this on their hardware. However, Sigrok is a decent alternative which supports a lot of devices. That includes the DS1000Z series, though I don't know if that includes the logic inputs. The OP might want to check them out.

https://sigrok.org/wiki/Supported_hardware

+1 for getting a LA for digital work. I started with a Saleae clone (dirt cheap and works), and loved it so much that I bought a Logic 8. They have a 50% discount for hobbyists which brought it down to an affordable luxury for me.

https://blog.saleae.com/saleae-discounts/

It's so true. There was an incredible influx of these folks after the dotcom boom, after the appropriate delay for them to get through college. Not that there's anything wrong with making money, but it was certainly a culture shift.

Like you say, it can be a mix. They can also happen at the same time. I am blessed that I can make a good living doing what I love.

I think the concept they're after is there are two large groups of people into tech: the people who enjoy it and are here because they're doing what they love; and the people who are here for the money.

I don't know if Conformity is the right word, unless you're viewing the world through a lens where everyone is working a job they hate just to survive.

I've absolutely noticed the culture shift over the years though. In the 90s it was a bunch of us creating things because we saw a way to do it, and we were making enough money that we didn't have to worry too much about how to pursue our visions. But money corrupts everything eventually. Geek fashion was definitely nonconformist for a while, but then became trendy - because it was associated with affluence.

I love being part of the Just For Fun crowd. It makes me versatile - I can pick up new technologies quickly because I love reading about them. Throw a problem at me and it's a puzzle I want to solve, not a chore.

That doesn't translate well to a resume or job listing, and over time it has certainly gotten harder to link up with other people who think this way and want to create things in this uninhibited, creative kind of way. It's one of the reasons I've jumped into HN. There are a lot of them here, and I want to make that be more of my world again.

McMurdo is on the edge of the continent, at sea level. It's harsh, but not extreme like the things further inland, such as Amundsen-Scott (at the geographic pole), or Concordia (over 10,000 feet elevation in the middle of nowhere). Those look closer to the spaceships you envision.

Did you zoom in? When I zoom in on one of the major intersections and look at the cars, it looks about right. Half-meter resolution means that each car should be several blurry pixels wide, and that's what I get.

Obligatory XKCD: https://xkcd.com/386/

It's solid advice.

I did it in the web UI in a couple minutes with down-space-down-space-down-space....

Also make sure to go to Advanced Options, View Deleted Items, and purge them from there.