The example under verilog/interactive showcases how to create a simple interactive visual Verilog example using Verilator and SDL.
https://raw.githubusercontent.com/cirosantilli/media/master/verilog-interactive.gif
You could e.g. expand such an example to create a simple (or complex) video game for example if you were insane enough. But please don't waste your time doing that, Ciro Santilli begs you.
Usage: install dependencies:
sudo apt install libsdl2-dev verilator
then run as either:
make run RUN=and2
make run RUN=move
Tested on Verilator 4.038, Ubuntu 22.04.
In those examples, the more interesting application specific logic is delegated to Verilog (e.g.: move game character on map), while boring timing and display matters can be handled by SDL and C++.
Stockfish CLI by Ciro Santilli 37 Updated 2025-10-14
Most of what follows is part of the Universal Chess Interface. Tested on Ubuntu 22.10, Stockfish 14.1.
After starting stockfish on the command line, d (presumably display) contains:
 +---+---+---+---+---+---+---+---+
 | r | n | b | q | k | b | n | r | 8
 +---+---+---+---+---+---+---+---+
 | p | p | p | p | p | p | p | p | 7
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   | 6
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   | 5
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   | 4
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   | 3
 +---+---+---+---+---+---+---+---+
 | P | P | P | P | P | P | P | P | 2
 +---+---+---+---+---+---+---+---+
 | R | N | B | Q | K | B | N | R | 1
 +---+---+---+---+---+---+---+---+
   a   b   c   d   e   f   g   h

Fen: rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1
Key: 8F8F01D4562F59FB
Sweet ASCII art. where:
Move white king's pawn from e2 to e4:
position startpos moves e2e4
Then display again:
d
gives:
 +---+---+---+---+---+---+---+---+
 | r | n | b | q | k | b | n | r | 8
 +---+---+---+---+---+---+---+---+
 | p | p | p | p | p | p | p | p | 7
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   | 6
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   | 5
 +---+---+---+---+---+---+---+---+
 |   |   |   |   | P |   |   |   | 4
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   | 3
 +---+---+---+---+---+---+---+---+
 | P | P | P | P |   | P | P | P | 2
 +---+---+---+---+---+---+---+---+
 | R | N | B | Q | K | B | N | R | 1
 +---+---+---+---+---+---+---+---+
   a   b   c   d   e   f   g   h

Fen: rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq - 0 1
Key: B46022469E3DD31B
so we see that the pawn moved.
Now let's make Stockfish think for one second what is the next best move for black:
go movetime 1000
gives as the last line:
bestmove c7c5 ponder g1f3
TODO:
  • what is ponder? Something to do with thinking on the opponent's turn: permanent brain.
  • understand the previous lines
To make the move it as suggested for black, we have to either repeat the entire sequence of movements:
position startpos moves e2e4 c7c5
d:
 +---+---+---+---+---+---+---+---+
 | r | n | b | q | k | b | n | r | 8
 +---+---+---+---+---+---+---+---+
 | p | p |   | p | p | p | p | p | 7
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   | 6
 +---+---+---+---+---+---+---+---+
 |   |   | p |   |   |   |   |   | 5
 +---+---+---+---+---+---+---+---+
 |   |   |   |   | P |   |   |   | 4
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   | 3
 +---+---+---+---+---+---+---+---+
 | P | P | P | P |   | P | P | P | 2
 +---+---+---+---+---+---+---+---+
 | R | N | B | Q | K | B | N | R | 1
 +---+---+---+---+---+---+---+---+
   a   b   c   d   e   f   g   h

Fen: rnbqkbnr/pp1ppppp/8/2p5/4P3/8/PPPP1PPP/RNBQKBNR w KQkq - 0 2
Key: 4CA78BCE9C2980B0
or alternatively we could also use the previous FEN notation as a starting point;
position fen rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq - 0 1 moves c7c5
Note how the Universal Chess Interface interface is very simple: we just load a state and then decide what to do next for that one state. The engine holds only one and exactly one state at a time, and you can't even modify it differentially without loading new one from scratch.
Let's move white again with our brain with either:
position startpos moves e2e4 c7c5 d2d3
position fen rnbqkbnr/pp1ppppp/8/2p5/4P3/8/PPPP1PPP/RNBQKBNR w KQkq - 0 2 moves d2d3
Set a specific position from fen:
position fen rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq - 0 1
Programming language by Ciro Santilli 37 Updated 2025-07-16
A language that allows you to talk to and command a computer.
There is only space for two languages at most in the world: the compiled one, and the interpreted one.
For 2020 now, when you have a choice, you must go for:
Those two are languages not by any means perfect from a language design point of view, and there are likely already better alternatives, they are only chosen due to a pragmatic tradeoff between ecosystem and familiarity.
Ciro predicts that Python will become like Fortran in the future: a legacy hated by most who have moved to JavaScript long ago (which is slightly inferior, but too similar, and with too much web dominance to be replaced), but with too much dominance in certain applications like machine learning to be worth replacing, like Fortran dominates certain HPC applications. We'll see. Maybe non performance critical scripting languages are easier to replace.
C++ however is decent, and is evolving in very good directions in the 2010's, and will remain relevant in the foreseeable future.
Bash can also be used when you're lazy. But if the project goes on, you will sooner or later regret that choice.
The language syntax in itself does not matter. All that matters is how many useful libraries and tooling it has.
This is how other languages compare:
Functional programming by Ciro Santilli 37 Updated 2025-07-16
Even if we cannot do everything in functional, we should at least strive to clearly extract functional substes in what we do.
VHDL by Ciro Santilli 37 Updated 2025-07-16
Examples under vhdl, more details at: GHDL.
Ciro Santilli thinks imperative programming is just a superset of functional programming where you can have state.
C and C++: OK, you're old before the Internet and compiled, forgiven.
Python: OMG, please, just make it work!!! Your are interpreted!!! You are a hot web technology!!! Node.js and Ruby are doing just fine, and Ruby is not newer than you!!! See also: pip.
Interestingly, the very first programming language with an actual implementation was interpreted: Short Code in 1950.
This is not surprising, as interpreters are easier to write than compilers.
And just like modern scripting languages, it reduced execution speed by about 50x.
for loop by Ciro Santilli 37 Updated 2025-07-16
The for loop is a subcase of the while loop.
One theoretical motivation for its existence is that it has the fundamental property that we are immediately certain it will terminate, unlike while loops with arbitrary conditions.
Primitive recursive functions are the complexity class that divides those two.

Pinned article: Introduction to the OurBigBook Project

Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
We have two killer features:
  1. topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculus
    Articles of different users are sorted by upvote within each article page. This feature is a bit like:
    • a Wikipedia where each user can have their own version of each article
    • a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
    This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
    Figure 1.
    Screenshot of the "Derivative" topic page
    . View it live at: ourbigbook.com/go/topic/derivative
  2. local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:
    This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
    Figure 2.
    You can publish local OurBigBook lightweight markup files to either https://OurBigBook.com or as a static website
    .
    Figure 3.
    Visual Studio Code extension installation
    .
    Figure 4.
    Visual Studio Code extension tree navigation
    .
    Figure 5.
    Web editor
    . You can also edit articles on the Web editor without installing anything locally.
    Video 3.
    Edit locally and publish demo
    . Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension.
    Video 4.
    OurBigBook Visual Studio Code extension editing and navigation demo
    . Source.
  3. https://raw.githubusercontent.com/ourbigbook/ourbigbook-media/master/feature/x/hilbert-space-arrow.png
  4. Infinitely deep tables of contents:
    Figure 6.
    Dynamic article tree with infinitely deep table of contents
    .
    Descendant pages can also show up as toplevel e.g.: ourbigbook.com/cirosantilli/chordate-subclade
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact