Huh, then you're one of today's lucky ten thousand!
Apollo 14 had a piece of loose solder in the button triggering abort-to-orbit, so it occassionally triggered itself. This wasn't a problem en route to the moon, but the second the descent phase started it would have been a Poisson-timed bomb that would prevent the landing.
There was a bit of memory that could be set to ignore the state of the abort button (this bit was the reason the abort sequence wasn't triggered en route). The problem was this ignore bit was reset by the landing sequence (to allow aborting once landing started), and they did not believe the astronauts would be quick enough to set the bit again before the button shorted out and triggered the abort.
(Ignoring the abort button was fine because an abort could be triggered in the computer instead. Takes a little longer but was determined a better option than scrapping the mission.)
Don Eyles came up with a clever hack. Setting the program state to 71 ("abort in progress") happened to both allow descent to start and prevented the abort button from being effective. So this program state was keyed in just before descent.
The drawback was that it obviously put the computer in an invalid state so some things were not scheduled correctly but Eyles and colleages had figured out which things and the astronauts could start those processes manually.
Then once the computer was in a reasonable state again the ignore abort bit could be set and the program mode set correctly and it was as if nothing had happened.
Apollo 14 had a piece of loose solder in the button triggering abort-to-orbit, so it occassionally triggered itself. This wasn't a problem en route to the moon, but the second the descent phase started it would have been a Poisson-timed bomb that would prevent the landing.
There was a bit of memory that could be set to ignore the state of the abort button (this bit was the reason the abort sequence wasn't triggered en route). The problem was this ignore bit was reset by the landing sequence (to allow aborting once landing started), and they did not believe the astronauts would be quick enough to set the bit again before the button shorted out and triggered the abort.
(Ignoring the abort button was fine because an abort could be triggered in the computer instead. Takes a little longer but was determined a better option than scrapping the mission.)
Don Eyles came up with a clever hack. Setting the program state to 71 ("abort in progress") happened to both allow descent to start and prevented the abort button from being effective. So this program state was keyed in just before descent.
The drawback was that it obviously put the computer in an invalid state so some things were not scheduled correctly but Eyles and colleages had figured out which things and the astronauts could start those processes manually.
Then once the computer was in a reasonable state again the ignore abort bit could be set and the program mode set correctly and it was as if nothing had happened.