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Separation of concerns by

Hidden Answers by

Ciro Santilli 37 Updated 2025-07-16

www.reddit.com/r/onions/comments/sfquss/hidden_answers_is_back/ gives pbqttnffb5sh6ckgnz4f5by55w25gd6tuw5f5qcctmnyk62eyhgx6rad.onion which is Dead Janary 2024

Selection (relational algebra) by

Universal Module Definition by

Ciro Santilli 37 Updated 2025-07-16

Since JavaScript devs are incapable of defining an unified import standard, this design pattern emerged where you just check every magic global one by one. Here's a demo where a Js library works on both the browser and from Node.js:

Beilinson regulator by

Compile MicroPython code for Micro Bit locally on Ubuntu 22.04 with your own firmware by

Ciro Santilli 37 Updated 2025-07-27

TODO didn't manage from source Ubuntu 22.04, their setup bitrotted way too fast... it's shameful even. Until I gave up and went for the magic Docker of + github.com/bbcmicrobit/micropython, and it bloody worked:

git clone https://github.com/bbcmicrobit/micropython
cd micropython
git checkout 7fc33d13b31a915cbe90dc5d515c6337b5fa1660
docker pull ghcr.io/carlosperate/microbit-toolchain:latest
docker run -v $(pwd):/home --rm ghcr.io/carlosperate/microbit-toolchain:latest yt target bbc-microbit-classic-gcc-nosd@https://github.com/lancaster-university/yotta-target-bbc-microbit-classic-gcc-nosd
docker run -v $(pwd):/home --rm ghcr.io/carlosperate/microbit-toolchain:latest make all

# Build one.
tools/makecombinedhex.py build/firmware.hex examples/counter.py -o build/counter.hex
cp build/counter.hex "/media/$USER/MICROBIT/"

# Build all.
for f in examples/*; do b="$(basename "$f")"; echo $b; tools/makecombinedhex.py build/firmware.hex "$f" -o "build/${b%.py}.hex"; done

The pre-Docker attempts:

sudo add-apt-repository -y ppa:team-gcc-arm-embedded
sudo apt update
sudo apt install gcc-arm-embedded
sudo apt install cmake ninja-build srecord libssl-dev

# Rust required for some Yotta component, OMG.
sudo snap install rustup
rustup default 1.64.0

python3 -m pip install yotta

The line:

sudo add-apt-repository -y ppa:team-gcc-arm-embedded

warns:

E: The repository 'https://ppa.launchpadcontent.net/team-gcc-arm-embedded/ppa/ubuntu jammy Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

and then the update/sudo apt-get install gcc-arm-embedded fails, bibliography:

Attempting to install Yotta:

sudo -H pip3 install yotta

or:

python3 -m pip install --user yotta

was failing with:

Exception: Version mismatch: this is the 'cffi' package version 1.15.1, located in '/tmp/pip-build-env-dinhie_9/overlay/local/lib/python3.10/dist-packages/cffi/api.py'.  When we import the top-level '_cffi_backend' extension module, we get version 1.15.0, located in '/usr/lib/python3/dist-packages/_cffi_backend.cpython-310-x86_64-linux-gnu.so'.  The two versions should be equal; check your installation.

Running:

python3 -m pip install --user cffi==1.15.1

did not help. Bibliography:

From a clean virtualenv, it appears to move further, and then fails at:

Building wheel for cmsis-pack-manager (pyproject.toml) ... error
error: [Errno 2] No such file or directory: 'cargo'

So we install Rust and try again, OMG:

sudo snap install rustup
rustup default stable

which at the time of writing was rustc 1.64.0, and then OMG, it worked!! We have the yt command.

However, it is still broken, e.g.:

git clone https://github.com/lancaster-university/microbit-samples
cd microbit-samples
git checkout 285f9acfb54fce2381339164b6fe5c1a7ebd39d5
cp source/examples/invaders/* source
yt clean
yt build

blows up:

annot import name 'soft_unicode' from 'markupsafe'

bibliography:

Micro Bit version by

Ciro Santilli 37 Updated 2025-07-16

Identification: kitronik.co.uk/blogs/resources/explore-micro-bit-v1-microbit-v2-differences The easiest thing is perhaps the GPIO notches.

Weierstrass product inequality by

Micro Bit GPIO by

Ciro Santilli 37 Updated 2025-07-16

Pinout overview: makecode.microbit.org/device/pins Basically 0, 1, and 2 are the truly generic ones. They can also serve as ADCs.

Micropython documentation: microbit-micropython.readthedocs.io/en/latest/pin.html

Covering lemma by

Audio feedback by

Ciro Santilli 37 Updated 2025-07-16

Information technology by

Ciro Santilli 37 Updated 2025-07-16

Digital electronic computer by

Ciro Santilli 37 Updated 2025-07-16

Unsurprisingly the term "computer" became a synonym for this from the 1960s onwards!

Gravity and electricity by Hermann Weyl (1918) by

Ciro Santilli 37 Updated 2025-07-16

Published on the session reports of the Royal Prussian Academy of Sciences at Berlin 1918 page 464.

Is about Maxwell's equations in curved spacetime, and notably introduces gauge theory.

Viewable for free at: archive.org/details/mobot31753002089727/page/464/mode/2up.

Competitive programming by

Ciro Santilli 37 Updated 2025-07-16

A waste of time like the rest of the knowledge olympiads.

IBM by

Ciro Santilli 37 Updated 2025-07-16

As of the 2020's, a slumbering giant.

But the pre-Internet impact of IBM was insane! Including notably:

some of the most important business computers of the pre-personal computer era
SQL
IBM Generalized Markup Language, which is a predecessor to XML and HTML

Lysozyme by

Ciro Santilli 37 Updated 2025-07-16

The second protein to have its structure determined, after myoglobin, by X-ray crystallography, in 1965.

Breaks up peptidoglycan present in the bacterial cell wall, which is thicker in Gram-positive bacteria, which is what this enzyme seems to target.

Part of the inate immune system.

It is present on basically everything that mammals and birds excrete, and it kills bacteria, both of which are reasons why it was discovered relatively early on.

Spin (physics) by

Ciro Santilli 37 Updated 2025-07-16

Spin is one of the defining properties of elementary particles, i.e. number that describes how an elementary particle behaves, much like electric charge and mass.

Possible values are half integer numbers: 0, 1/2, 1, 3/2, and so on.

The approach shown in this section: Section "Spin comes naturally when adding relativity to quantum mechanics" shows what the spin number actually means in general. As shown there, the spin number it is a direct consequence of having the laws of nature be Lorentz invariant. Different spin numbers are just different ways in which this can be achieved as per different Representation of the Lorentz group.

Video 1. "Quantum Mechanics 9a - Photon Spin and Schrodinger's Cat I by ViaScience (2013)" explains nicely how:

incorporated into the Dirac equation as a natural consequence of special relativity corrections, but not naturally present in the Schrödinger equation, see also: the Dirac equation predicts spin
photon spin can be either linear or circular
the linear one can be made from a superposition of circular ones
straight antennas produce linearly polarized photos, and Helical antennas circularly polarized ones
a jump between 2s and 2p in an atom changes angular momentum. Therefore, the photon must carry angular momentum as well as energy.
cannot be classically explained, because even for a very large estimate of the electron size, its surface would have to spin faster than light to achieve that magnetic momentum with the known electron charge
as shown at Video "Quantum Mechanics 12b - Dirac Equation II by ViaScience (2015)", observers in different frames of reference see different spin states

Video 1.

Quantum Mechanics 9a - Photon Spin and Schrodinger's Cat I by ViaScience (2013)

Source.

Video 2.

Quantum Spin - Visualizing the physics and mathematics by Physics Videos by Eugene Khutoryansky (2016)

Source.

Video 3.

Understanding QFT - Episode 1 by Highly Entropic Mind (2023)

Source. Maybe he stands a chance.