Margaret Hamilton Apollo 11 Software

Margaret Hamilton, as Director of Software Engineering for the Apollo program, led the team that developed the Lunar Module's guidance computer software. The commonly cited figure is approximately 65,000 lines of code for the lunar module's onboard software.

However, it's important to note that Hamilton led the team that wrote this code rather than writing it all herself—she was the director overseeing the software effort. Her critical contribution was establishing rigorous software engineering practices, error handling, and testing protocols that were novel for the time and helped ensure the mission's success. Her work fundamentally elevated software engineering as a discipline and earned her the Presidential Medal of Freedom in 2016.

They used AGC Assembly Language (AGC stands for Apollo Guidance Computer), which was specifically designed for the Apollo Guidance Computer hardware aboard the spacecraft.

AGC Assembly was a low-level assembly language because the onboard computer had extremely limited resources—the AGC had only about 64 kilobytes of memory total. Every instruction had to be carefully optimized. The language reflected the constraints of 1960s computing hardware and required deep technical precision, which made the rigorous software engineering practices Hamilton championed even more critical to mission success.

Margaret Hamilton worked for MIT's Instrumentation Laboratory (which later became the Draper Laboratory). Her immediate supervisor was Hal Laning, who headed the software division at MIT IL.

The laboratory itself was directed by Charles Stark Draper, a pioneering figure in inertial guidance systems. MIT's Instrumentation Laboratory had been contracted by NASA to develop the guidance and navigation system for the Apollo spacecraft, which is why Hamilton's software engineering work became so central to the mission.