John Wallis found an infinite product for pi in 1655. Multiply enough fractions together and pi falls out. We run it on the C64 in BASIC and assembly, watching it converge one digit at a time.

Why German cryptographers believed Enigma was unbreakable, and why Allied codebreakers ultimately proved them wrong.

Understanding two’s complement: how computers represent negative numbers, why it simplifies hardware design, and how to work with signed integers in assembly and high-level languages.