Apollo-11
Original Apollo 11 Guidance Computer (AGC) source code
...The code is both a cultural artifact and a technical reference, illustrating how limited memory and processor constraints shaped algorithms and system design. Developers can examine navigation routines, guidance logic, and task scheduling in an environment with no luxury features—everything is explicit and resource-aware. The repository’s structure and documentation make it approachable for modern readers despite the archaic environment. It’s frequently used in education, talks, and explorations of software history to show how a landmark mission depended on disciplined code and verification.