Scott Manley tells the story
<https://www.youtube.com/watch?v=wSSmNUl9Snw> of how the Apollo 14
mission was saved by a truly remarkable bit of computer hacking.
You might be thinking: “Have you tried turning it off and on again?”
Apollo 10 did that. And there were the computer crashes (“1202 alarm”
and “1201 alarm”) during the Apollo 11 landing. But 14 was being
stymied by an intermittently-shorting abort switch: if that triggered
at the wrong time, the mission was over. And the software couldn’t be
reprogrammed, since it was all woven (literally) into ROM.
So a bright young guy named Don Eyles was woken up in the middle of the
night, and over the space of a couple of hours he put together a
sequence of manual patches to the writable memory to temporarily disable
the abort switch at crucial moments, with further patches necessary to
deal with the consequences of this elsewhere in the code.
The astronauts had to follow the instructions and key in the numbers
exactly as given. (Upload? What upload?) This included having to
manually crank the descent engine up to full thrust at the right time,
because the automatic program for doing so would not be working.
Anyway, as history records, they successfully made it down to the lunar
surface, and back home again. Mission accomplished.
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