Nearly 50 years ago on the 20th of July 1969 humans set foot on the moon for the first time. Among the many extraordinary engineering feats that made this possible was the Apollo Guidance Computer, an innovative processor for its time with an instruction set that was thought up well before the advent of C. So 50 years later, why not implement support for it in a modern compiler such as LLVM?

This talk will give a brief overview of some of the architectural features of the Apollo Guidance Computer followed by an account of my implementation of an LLVM target so far. The shortcomings of LLVM when it comes to implementing such an unusual architecture will be discussed along with the workarounds used to overcome them.