PoliCTF 2017 - PowderToy CPU

Why reverse a program when you can reverse a computer & CPU with custom ISA?

Program CPU description

This CPU is a save file of Powder Toy;
From the website: “The Powder Toy is a free physics sandbox game… The game provides you with various building materials, liquids, gases and electronic components”

I have, in a moment of madness ;), decided to build a cpu, painting it by hand pixel after pixel…

Making a cpu is something that was on my “todo list” from some time and this was the perfect opportunity!

Here you can find a document describing the parts, how do they work, the program that it execute, and the flag.

Download pdf writeup
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Download Solved challenge

Thanks anyone for playing!
Greetings from Italy
Nesos