The more I read about the 1201 & 1202 alarms during Apollo 11 the more I realize the existing narrative isn't quite true. The alarms were supposed to indicate that the computer was overloaded, restarting and killing off some tasks causing the load.

Specifically, when the crew started up a routine to monitor their delta-H - i.e. descent rate, it pushed the computer over the edge because of extra interrupts being generated by the rendezvous radar.

Anything that had to read data from instruments was the highest priority, because that data might be lost if it wasn't tended to. But the actual work of doing the math was carried out by the servicer which would be kicked off every 2 seconds to set the attitude and throttle.

Servicer was like a background task that didn't directly read data, so it was the lowest priority. And that meant when CPU cycles got tight it would be interrupted. Now, it would run to completion eventually, but every 2 second a new servicer would be queued and forced to wait.

The Alarms were due to too many servicer tasks waiting to run, they were allocated chunks of memory to store temporary data. And when they ran out of memory the alarm was triggered, all the queued tasks were cleaned up and things continued.

But what this means is that the task actually updating attitude and throttle to make a soft landing was running less frequently than it should.
In fact if loads were a bit higher it would be locked out completely and the spacecraft landing autopilot wouldn't do anything.

So while the documentaries say the AGC was dropping 'low priority tasks', what they don't mention is the low priority task was the one actually flying the descent!
The other low priority task was updating the display on the DSKY, when that went blank thins were getting bad.

It's a story for which there are a bunch of false narratives, partly because even the people involved didn't figure out the truth at the time. The Rendezvous Radar configuration wasn't a mistake and the extra load it caused was almost entirely down to bad luck.