So compass and straight edge is Turing complete ? Amazing !
this post was submitted on 17 Feb 2026
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Not really…? You should read the article.
It's not a very long article and it doesn't really explain anything, it just says that it's been done. But I don't really understand how that runs a game boy game?
"also altered a Game Boy emulator to implement the ALU instructions using compass and straightedge operations"
The title is a lie. It's using a computer as usual, with extra steps - instead of using the CPU as intended it simulates the mentioned tools/techniques
I just don't understand how you can use a compass and straight edge to emulate an instruction set. The article just doesn't explain it; it's just like, "Of course this is a thing."
To add two numbers, for example, it constructs the midpoint between them, then doubles the distance from the origin.
It's basically a self-defined system of arithmetic, with no actual numbers. e.g. rather than 1 + 2 = 3, you have [radius of unit circle A] + [radius of 2 unit circle B] = [length of 3 unit line C]. I'll confess I don't totally understand how you can extend that to the point that it can correctly implement RSA, but I believe it can be done based on other achievements with unquantified geometry I've witnessed in the past.
For example, this excellent video about constructing flags using only the shape drawing tools of PowerPoint without ever applying external measurements to the shapes.
But Can it run doom and Minecraft?