1201 Alarm Press

Narrative from the website of the publisher, 1201 Alarm Press :-

Screenshot of website of 1201 Alarm Press 

(Certain paragraphs marked and numbered for analysis)

1201 Alarm History

On July 20, 1969, as the Apollo 11 lunar module (the first

manned lunar landing) was descending, the computerized guidance system began repeatedly reporting a “1201 alarm.”

The computer¹s most vital function during this critical phase of the mission, determining the altitude and position of the craft, suffered a serious disruption. Because of a mistake in the astronauts' checklist, equipment was continuouslyoperating when it should have been inactive, consuming too much of the computer’s processing capacity.

This mistake created delays in some guidance calculations while leaving others unfinished. Had the 1201 alarm—a warning that the computer’s calculations were off and could not be trusted—not gone off, the lunar module likely would have crash-landed in a field of boulders, and astronauts Buzz Aldrin and Neil Armstrong would have perished.

1201 Alarm Press views this near-catastrophic event as analogous to the human condition called Attention-Deficit/Hyperactivity Disorder (AD/HD), in which the brain is misprocessing information and causing problematic behavior, but often so subtly that it appears to be functioning normally. 

As with the Apollo 11’s computer misprocessing, AD/HD is not so damaging as to prevent superficially normal operation. Yet the misprocessing is significant enough to create many serious effects that can eventually destroy both body and spirit.   

Because the magnitude of AD/HD's effects is often underappreciated by the general public as well as many healthcare professionals, we established 1201 Alarm Press in 2008 with the mission of educating the public about this common and highly genetic condition.

Article from the Humor Collection at Netjeff.com :-

An interview with Principal Designer of Lunar Module Computer Descent Software, Allan Klump

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If you listen to recordings of the landing, you will hear the Capcom say "1201 alarm" and "1202 alarm." The astronauts' checklist had erroneously called for the astronauts to turn on the rendezvous radar before initiation of the descent. Subsequently, the program that managed the radar began demanding too much of the computer's spare margin of time.  The power supply for the radar was not properly synchronized with the LM's main power supply.  Consequently, as the two power supplies went in and out of synchronization, the rendezvous radar generated many spurious input signals to the LM's computer. In responding to these signals, the computer delayed some of its guidance calculations and left others unfinished.  This situation caused the computer to issue alarms during the landing.

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What would the computer have done if the LM's descent engine quit cold a mile above the moon?  Allan said the astronauts simply would have pressed an abort button, which would have jettisoned the descent stage and ignited the ascent engine for return to the CM. 

Narrative from Apollo 11 Lunar Space Journal at NASA Website :-

I thought you might be interested in some more detail about the 1201 and 1202 program alarms that occurred durning the Apollo 11 lunar landing. I and my good friend Don Eyles were two of the 'young experts' at the MIT Instrumentation Lab - Draper Lab - who worked on the software for the LEM guidance computer.

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So what was happening during Apollo 11, as I recall, was that repeated jobs to process rendezvous radar data (that of course were not really there) were scheduled because a misconfiguration of the radar switches. Thus, the core sets got filled up and a 1202 alarm was generated. The 1201 that came later in the landing was because the scheduling request that caused the actual overflow was one that had requested a VAC area.

What happened next in either case was what you described as, 'The computer has been programmed to recognize this data as being of secondary importance and will ignore it while it does more important computations.' It was a little more than that, and had been the subject of a great deal of testing before the software had been released. The software rebooted and reinitialized the computer, and then restarted selected programs at a point in their execution flow near where they had been when the restart occurred. To give you an example in today's terms, right now I have Windows95 with Netscape Communicator active as I compose this message. In the background, an audio CD is playing. WordPerfect is open, but has no active document, and Quicken has my checking account open. If I were to reboot now, all of those programs would be closed down. If Windows was a smart as the Apollo LGC executive, after the reboot the CD might not be playing and WordPerfect might not be there, but I would come back to this message composition window, with the same text displayed, and Quicken would have my checking account open to the proper place.

On Apollo 11, each time a 1201 or 1202 alarm appeared, the computer rebooted, restarted the important stuff, like steering the descent engine and running the DSKY to let the crew know what was going on, but did not restart all the erroneously-scheduled rendezvous radar jobs. The NASA guys in the MOCR knew - because MIT had extensively tested the restart capability - that the mission could go forward.