In the mid-1960s, the necessary technology to create the flight software for the Apollo 11 space program did not exist. Programmers at the MIT Instrumentation Laboratory had painstakingly invent it- line by line.
Assembly itself is obscure to many of today’s programmers—it’s very difficult to read, intended to be easily understood by computers, not humans. For the Apollo Guidance Computer (AGC), MIT programmers wrote thousands of lines of that esoteric code. They came up with a new way to store computer programs, called “rope memory,” and created a special version of the assembly programming language.
Margaret Hamilton, director of software engineering for the project, took a black-and-white picture standing next to a stack of paper containing the software to commemorate their success. And let’s just say she saw eye-to-eye it with!
The AGC code has been available to the public for quite a while–it was first uploaded by tech researcher Ron Burkey in 2003, after he’d transcribed it from scanned images of the original hardcopies MIT had put online. That is, he manually typed out each line, one by one.
“It was scanned by a airplane pilot named Gary Neff in Colorado,” Burkey said in an email. “MIT got hold of the scans and put them online in the form of page images, which unfortunately had been mutilated in the process to the point of being unreadable in places.” Burkey reconstructed the unreadable parts, he said, using his engineering skills to fill in the blanks.
“Quite a bit later, I managed to get some replacement scans from Gary Neff for the unreadable parts and fortunately found out that the parts I filled in were 100% correct!” he said.
However, the code itself remained somewhat obscure to many of today’s software developers. That was until last Thursday (July 7), when former NASA intern Chris Garry uploaded the software in its entirety to GitHub, the code-sharing site where millions of programmers hang out these days.
