Apollo 11 Guidance Computer source code for the command and lunar modules (opens in new tab)

That call to STOPRATE was there to zero out attitude rate commands at the moment the astronaut switches into the semimanual final descent program P66. It was removed in the final few revisions before the first, unflown release of the Apollo 14 software (Luminary 163 [1]) because it was preventing attitude control of the spacecraft when Rate-Of-Descent commands were skipped [2]. Skipping ROD commands wasn't normal, but was something that was added as part of the effort to make the computer more cleanly handle large unexpected additional load, like happened in Apollo 11.

[1] https://github.com/virtualagc/virtualagc/blob/master/Luminar...

[2] http://www.ibiblio.org/apollo/Documents/LUM156_text.pdf -- look for PCN 1037

People frequently seem to think this is about the line number it's on (666), but that doesn't have anything to do with it. That line number is a totally modern construction; the original source code was on punch cards. That particular comment was punched onto card number 0562 in the LUNAR LANDING GUIDANCE EQUATIONS log section. The original developers only referred to code by punch card number, and page number in the listing. So it really is just a coincidence, and the "NUMERO MYSTERIOSO" is referring to whatever is in GAINBRAK,1.

It's kind of frustrating to try and figure out what is actually the original, unaltered code, and what's been added.

There is a BURNBABY routine, though, so I guess that's real.

It makes sense in context, of course, I just didn't think of NASA in the late 60ies as the sort of place where you could write 'clever' things like that.

My bad, didn't realize that it's been out for a while.

He was an employee at NASA several years ago.